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Cristian SECCHI
Professore Ordinario
Dipartimento di Scienze e Metodi dell'Ingegneria
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Pubblicazioni
- Predictive Rolling Bearing Maintenance
[Brevetto]
Cocconcelli, Marco; L., Bassi; D., Borghi; Rubini, Riccardo; Secchi, Cristian
abstract
A method of predicting a fault in a rolling bearing, the rolling bearing including inner and outer rings and rolling bodies evenly angularly distributed therebetween, the method comprising:. processing (in the DSP system 8) a position signal (x(t)) indicative of a relative angular position of the inner ring with respect to the outer rings, and a vibration signal (y(t)) (by the accelerometer 7) indicative of speed-related vibrations in the rolling bearing, such that they correspond to either an angular displacement of the rolling bodies equal to an integer number of angular gaps between adjacent rolling bodies or an integer number of complete rotations of the inner ring with respect to the outer ring; . space sampling (in the A/D acquisition board 9) the processed vibration signal (y(t)) based on the processed position signal (x(t)); and. predicting a fault in the rolling bearing based on the space-sampled vibration signal (y(t)).
2024
- A Dynamic Planner for Safe and Predictable Human-Robot Collaboration
[Articolo su rivista]
Pupa, A.; Minelli, M.; Secchi, C.
abstract
2023
- A Comparison of Signal Analysis Techniques for the Diagnostics of the IMS Rolling Element Bearing Dataset
[Articolo su rivista]
Sacerdoti, Diletta; Strozzi, Matteo; Secchi, Cristian
abstract
In this paper, a comparison of signal analysis techniques for the diagnostics of rolling element bearings is carried out. Specifically, the comparison is performed in terms of fault detection, diagnosis and prognosis techniques with regards to the first rolling element bearing dataset released by NASA IMS Center in 2014. As for fault detection, it is obtained that RMS value, Kurtosis and Detectivity, as statistical parameters, are able to properly detect the arising of the fault on the defective
bearings. Then, several signal processing techniques, such as deterministic/random signal separation, time-frequency and cyclostationary analyses are applied to perform fault diagnosis. Among these techniques, it is found that the combination of Cepstrum Pre-Whitening and Squared Envelope Spectrum, and Improved Envelope Spectrum, allow the faults to be correctly identified on specific bearing components. Finally, the Correlation, Monotonicity and Robustness of the previous statistical parameters are computed to identify the most accurate tools for bearing fault prognosis.
2023
- A General Pipeline for Online Gesture Recognition in Human–Robot Interaction
[Articolo su rivista]
Villani, Valeria; Secchi, Cristian; Lippi, Marco; Sabattini, Lorenzo
abstract
2022
- A Resilient and Effective Task Scheduling Approach for Industrial Human-Robot Collaboration
[Articolo su rivista]
Pupa, A.; Van Dijk, W.; Brekelmans, C.; Secchi, C.
abstract
Effective task scheduling in human-robot collaboration (HRC) scenarios is one of the great challenges of collaborative robotics. The shared workspace inside an industrial setting brings a lot of uncertainties that cannot be foreseen. A prior offline task scheduling strategy is ineffective in dealing with these uncertainties. In this paper, a novel online framework to achieve a resilient and reliable task schedule is presented. The framework can deal with deviations that occur during operation, different operator skills, error by the human or robot, and substitution of actors, while maintaining an efficient schedule by promoting parallel human-robot work. First, the collaborative job and the possible deviations are represented by AND/OR graphs. Subsequently, the proposed architecture chooses the most suitable path to improve the collaboration. If some failures occur, the AND/OR graph is adapted locally, allowing the collaboration to be completed. The framework is validated in an industrial assembly scenario with a Franka Emika Panda collaborative robot.
2022
- Adaptive Tank-based Control for Aerial Physical Interaction with Uncertain Dynamic Environments Using Energy-Task Estimation
[Articolo su rivista]
Benzi, F.; Brunner, M.; Tognon, M.; Secchi, C.; Siegwart, R.
abstract
While aerial manipulation has witnessed noticeable growth as a field in the last decade, most works investigated forms of interaction with static and rigid environments only. Whenever dynamic environments were considered, the employed methods often relied on the knowledge of the model of the environment, which in most real applications cannot be obtained. In this work, we propose an adaptive controller for a fully actuated UAV performing stable and efficient physical interaction tasks with unmodeled and dynamic objects moving in unknown environments. We develop a passive time-varying impedance controller and wrench tracking controller, whose adaptable parameters allow us to minimize tracking error and instabilities during the execution of the interaction task. Robust stability is guaranteed by energy tanks, with the addition of a task-based formulation for adapting online the tank parameters in order to always provide the system with an adequate amount of energy. The control framework is validated both in simulations and experimentally by interacting with an unmodeled cart moving in passive time-varying environments, while subjected to unknown disturbances.
2022
- An Energy-Based Control Architecture for Shared Autonomy
[Articolo su rivista]
Benzi, F.; Ferraguti, F.; Riggio, G.; Secchi, C.
abstract
In robotic applications where the autonomy is shared between the human and the robot, the autonomous behavior of the robotic system is determined considering mainly the task to be executed and the data collected from the environment using, e.g., formal methods and machine learning techniques. Nevertheless, it is important to correctly translate high-level decision into low-level control inputs in order to avoid an unstable behavior due to a naive implementation of the autonomy. In this article, we propose an energy-based architecture for shared autonomy that allows to reproduce as closely as possible the desired behavior, while ensuring a robust stability of the robotic system. The proposed architecture is experimentally validated in two application scenarios: shared control of a multirobot system and variable admittance control in human robot collaboration
2022
- Bidirectional Communication Control for Human-Robot Collaboration
[Relazione in Atti di Convegno]
Ferrari, D.; Benzi, F.; Secchi, C.
abstract
A fruitful collaboration is based on the mutual knowledge of each other skills and on the possibility of communicating their own limits and proposing alternatives to adapt the execution of a task to the capabilities of the collaborators. This paper aims at reproducing such a scenario in a human-robot collaboration setting by proposing a novel communication control architecture. Exploiting control barrier functions, the robot is made aware of its (dynamic) skills and limits and, thanks to a local predictor, it is able to assess if it is possible to execute a requested task and, if not, to propose alternative by relaxing some constraints. The controller is interfaced with a communication infrastructure that enables human and robot to set up a bidirectional communication about the task to execute and the human to take an informed decision on the behavior of the robot. A comparative experimental validation is proposed.
2022
- Improving the Feasibility of DS-based Collision Avoidance Using Non-Linear Model Predictive Control
[Relazione in Atti di Convegno]
Farsoni, S.; Sozzi, A.; Minelli, M.; Secchi, C.; Bonfe, M.
abstract
In this paper we present a novel strategy for reactive collision-free feasible motion planning for robotic manipulators operating inside an environment populated by moving obstacles. The proposed strategy embeds the Dynamical System (DS) based obstacle avoidance algorithm into a constrained non-linear optimization problem following the Model Predictive Control (MPC) approach. The solution of the problem allows the robot to avoid undesired collision with moving obstacles ensuring at the same time that its motion is feasible and does not overcome the designed constraints on velocity and acceleration. Simulations demonstrate that the introduction of the MPC prediction horizon helps the optimization solver in finding the solution leading to obstacle avoidance in situations where a non predictive implementation of the DS-based method would fail. Finally, the proposed strategy has been validated in an experimental work-cell using a Franka-Emika Panda robot.
2022
- Passivity and Control Barrier Functions: Optimizing the Use of Energy
[Articolo su rivista]
Capelli, B.; Secchi, C.; Sabattini, L.
abstract
Passivity-based control ensures the implementation of a desired behavior in a controlled system, while preserving robust stability. In this letter, we propose a new method to guarantee passivity, based on energy-tank control and Control Barrier Functions. The goal is to accomplish a desired behavior with minimal modification, while ensuring passivity. The proposed method is suitable for a wide range of applications: whenever some desired control action may disrupt the passivity of the system, the designed Control Barrier Function will modify the behavior to enforce the preservation of passivity. Simulations and real experiments were carried out to prove the effectiveness and the flexibility of the proposed method: in particular, a simple case of variable stiffness in a mass-spring-damper system and a multi-robot controller based on a time-varying artificial potential field.
2022
- Safety and Efficiency in Robotics: The Control Barrier Functions Approach
[Articolo su rivista]
Ferraguti, F.; Talignani Landi, C.; Singletary, A.; Lin, H.; Ames, A.; Secchi, C.; Bonfe, M.
abstract
2021
- A Dynamic Architecture for Task Assignment and Scheduling for Collaborative Robotic Cells
[Capitolo/Saggio]
Pupa, A.; Landi, C. T.; Bertolani, M.; Secchi, C.
abstract
In collaborative robotic cells, a human operator and a robot share the workspace in order to execute a common job, consisting of a set of tasks. A proper allocation and scheduling of the tasks for the human and for the robot is crucial for achieving an efficient human-robot collaboration. In order to deal with the dynamic and unpredictable behavior of the human and for allowing the human and the robot to negotiate about the tasks to be executed, a two layers architecture for solving the task allocation and scheduling problem is proposed. The first layer optimally solves the task allocation problem considering nominal execution times. The second layer, which is reactive, adapts online the sequence of tasks to be executed by the robot considering deviations from the nominal behaviors and requests coming from the human and from robot. The proposed architecture is experimentally validated on a collaborative assembly job.
2021
- A First Evaluation of a Multi-Modal Learning System to Control Surgical Assistant Robots via Action Segmentation
[Articolo su rivista]
De Rossi, Giacomo; Minelli, Marco; Roin, Serena; Falezza, Fabio; Sozzi, Alessio; Ferraguti, Federica; Setti, Francesco; Bonfè, Marcello; Secchi, Cristian; Muradore, Riccardo
abstract
2021
- A Human-Centered Dynamic Scheduling Architecture for Collaborative Application
[Articolo su rivista]
Pupa, A.; Van Dijk, W.; Secchi, C.
abstract
In collaborative robotic applications, human and robot have to work together during a whole shift for executing a sequence of jobs. The performance of the human robot team can be enhanced by scheduling the right tasks to the human and the robot. The scheduling should consider the task execution constraints, the variability in the task execution by the human, and the job quality of the human. Therefore, it is necessary to dynamically schedule the assigned tasks. In this letter, we propose a two-layered architecture for task allocation and scheduling in a collaborative cell. Job quality is explicitly considered during the allocation of the tasks and over a sequence of jobs. The tasks are dynamically scheduled based on the real time monitoring of the human's activities. The effectiveness of the proposed architecture is experimentally validated.
2021
- A Safety-Aware Architecture for Task Scheduling and Execution for Human-Robot Collaboration
[Relazione in Atti di Convegno]
Pupa, A.; Secchi, C.
abstract
In collaborative robotic applications, human and robot have to work together to accomplish a common job, composed by a set of tasks. In order to achieve an efficient human-robot collaboration (HRC), it is important to have an integration between a proper task scheduling strategy and a task execution strategy. The first must deal with the variability of the two agents, while the second must deal with the safety standards. In this paper, we propose an integrated architecture for task scheduling and execution in a collaborative cell. The tasks are dynamically scheduled handling the uncertainity in both the human and the robot behaviors. Subsequently, at the execution level, the task is accomplished computing trajectories comply with the safety regulations. The planning information are mutually integrated in real-time with the scheduling procedure in order improve the HRC.
2021
- A Safety-Aware Kinodynamic Architecture for Human-Robot Collaboration
[Articolo su rivista]
Pupa, A.; Arrfou, M.; Andreoni, G.; Secchi, C.
abstract
The new paradigm of human-robot collaboration has led to the creation of shared work environments in which humans and robots work in close contact with each other. Consequently, the safety regulations have been updated addressing these new scenarios. The mere application of these regulations may lead to a very inefficient behavior of the robot. In order to preserve safety for the human operators and allow the robot to reach a desired configuration in a safe and efficient way, a two layers architecture for trajectory planning and scaling is proposed. The first layer calculates the nominal trajectory and continuously adapts it based on the human behavior. The second layer, which explicitly considers the safety regulations, scales the robot velocity and requests for a new trajectory if the robot speed drops. The proposed architecture is experimentally validated on a Pilz PRBT manipulator.
2021
- A two-layer trilateral teleoperation architecture for mentoring in surgical training
[Relazione in Atti di Convegno]
Minelli, M.; Loschi, F.; Ferraguti, F.; Secchi, C.
abstract
In this paper we propose a novel trilateral dual-master-single-slave teleoperation control architecture that can be used for the training of novice surgeons in surgical procedures. Starting from the concept of energy tank, we propose a flexible and stable trilateral interconnection over a delayed communication channel between the masters and the slave. Exploiting the flexibility provided by the controller, we design a training strategy for novice surgeons. The proposed architecture is experimentally validated.
2021
- An Optimization Approach for a Robust and Flexible Control in Collaborative Applications
[Relazione in Atti di Convegno]
Benzi, F.; Secchi, C.
abstract
In Human-Robot Collaboration, the robot operates in a highly dynamic environment. Thus, it is pivotal to guarantee the robust stability of the system during the interaction but also a high flexibility of the robot behavior in order to ensure safety and reactivity to the variable conditions of the collaborative scenario. In this paper we propose a control architecture capable of maximizing the flexibility of the robot while guaranteeing a stable behavior when physically interacting with the environment. This is achieved by combining an energy tank based variable admittance architecture with control barrier functions. The proposed architecture is experimentally validated on a collaborative robot.
2021
- An Optimized Two-Layer Approach for Efficient and Robustly Stable Bilateral Teleoperation
[Relazione in Atti di Convegno]
Loschi, F.; Piccinelli, N.; Dall'Alba, D.; Muradore, R.; Fiorini, P.; Secchi, C.
abstract
In this paper, we propose a novel bilateral teleoperation architecture that allows to optimally render the remote interaction force at the local side while guaranteeing a robustly stable behaviour. Stability is guaranteed by ensuring a proper energy exchange between the local and the remote sides. Desired performance is obtained by optimizing the way energy is exploited for generating the behaviour at each side. The effectiveness of the proposed architecture is experimentally validated on a torque-controlled manipulator and in a surgical scenario, using the da Vinci® Research Kit (dVRK).
2021
- An actor-critic strategy for a safe and efficient human robot collaboration
[Relazione in Atti di Convegno]
Gabrielli, G.; Secchi, C.
abstract
Fulfilling the ISO/TS 15066 regulation is crucial for implementing a certifiable human-robot collaborative application. If not properly embedded in the definition of the control action for the robot, the application of ISO/TS 15066 requirements can lead to a conservative and inefficient behavior of the robot. In order to maximize the performance, in this paper we propose an approach based on Deep Reinforcement Learning (DRL) for integrating the safety standards in a collaborative application. The proposed strategy is experimentally validated.
2021
- Dynamic-based RCM Torque Controller for Robotic-Assisted Minimally Invasive Surgery
[Relazione in Atti di Convegno]
Minelli, M.; Secchi, C.
abstract
In this paper we propose a novel flexible and optimization-free controller for standard torque-controlled manipulator for Robotic-Assisted Minimally Invasive Surgery. A novel method has been developed to model the constraint introduced by the laparoscopic tool, i.e. the remote center of motion, exploiting closed chain manipulators theory, and the final controller was synthesized considering the effects the constraint produces at a dynamic level. A set of simulations has been performed in a trajectory tracking task to validate the performances of the proposed controller. Performances have been also tested in a real experimental scenario with a KUKA LWR 4+ with 7 degrees of freedom endowed with a laparoscopic-like tool. Results show the effectiveness of the proposed controller and its capability of modifying the trajectory in order to preserve the RCM constraint.
2021
- Feasibility of a telementoring approach as a practical training for transurethral enucleation of the benign prostatic hyperplasia using bipolar energy: a pilot study
[Articolo su rivista]
Amato, M.; Eissa, A.; Puliatti, S.; Secchi, C.; Ferraguti, F.; Minelli, M.; Meneghini, A.; Landi, I.; Guarino, G.; Sighinolfi, M. C.; Rocco, B.; Bianchi, G.; Micali, S.
abstract
Introduction: Telementoring is one of the applications of telemedicine capable of bringing highly experienced surgeons to areas lacking expertise. In the current study, we aimed to assess a novel telementoring application during the learning curve of transurethral enucleation of the prostate using bipolar energy (TUEB). Material and methods: A telementoring system was developed by our engineering department. This application was used to mentor ten prospective cases of TUEB performed by an expert endourologist (novice to the TUEB). A questionnaire was filled by the operating surgeon and the mentor to provide subjective evaluation of the telementoring system. Finally, the outcomes of these patients were compared to a control group consisting of ten consecutive patients performed by the mentor. Results: Ten consecutive TUEB were performed using this telementoring application. Delayed and interrupted connection were experienced in two and one patients, respectively; however, their effect was minor, and they did not compromise the safety of the procedure. None of the patients required conversion to conventional transurethral resection of the prostate. Only one patient in our series experienced grade IIIb complication. Conclusion: The telementoring application for TUEB is promising. It is a simple and low-cost tool that could be a feasible option to ensure patients’ safety during the initial phase of the learning curve without time and locations constraints for both the mentor and the trainee; However, it should be mentioned that telementoring cannot yet replace the traditional surgical training with the mentor and trainee being in the operative room. Further studies are required to confirm the current results
2021
- Optimized power modulation in wave based bilateral teleoperation
[Articolo su rivista]
Ferraguti, Federica; Bonfe, Marcello; Fantuzzi, Cesare; Secchi, Cristian
abstract
2020
- A Control Barrier Function Approach for Maximizing Performance while Fulfilling to ISO/TS 15066 Regulations
[Articolo su rivista]
Ferraguti, F.; Bertuletti, M.; Landi, C. T.; Bonfe, M.; Fantuzzi, C.; Secchi, C.
abstract
ISO/TS 15066 is globally recognized as the guideline for designing safe collaborative robotic cells, where human and robot collaborate in order to fulfill a common job. Current approaches for implementing the ISO/TS 15066 guidelines lead to a conservative behavior (e.g. low velocity) of the robot and, consequently, to poor performance of the collaborative cell. In this letter, we propose an approach based on control barrier functions that allows to maximize the performance of a robot acting in a collaborative cell while satisfying the ISO/TS 15066 regulations. The proposed approach has been successfully validated both in simulation and through experiments.
2020
- A Passivity-Based Approach for Simulating Satellite Dynamics With Robots: Discrete-Time Integration and Time-Delay Compensation
[Articolo su rivista]
De Stefano, Marco; Balachandran, Ribin; Secchi, Cristian
abstract
This article proposes a passivity-based approach for simulating satellite dynamics on a position-controlled robot equipped with a force–torque sensor. Time delays intrinsic in the computational loop and discrete-time integration degrade the behavior of the satellite dynamics reproduced by the robot. These factors can generate an energy-inconsistent simulation and can even render the system unstable. In this article, time delay and discrete-time integration effects are analyzed from an energetic perspective and compensated through a passivity-based control strategy to ensure a faithful and stable dynamic simulation with position-controlled robots. The benefit of the proposed strategy is validated by simulations and experiments on the On-Orbit Servicing Simulator (OOS-SIM), a robotic facility used for simulating free-floating dynamics.
2020
- A Set-Theoretic Approach to Multi-Task Execution and Prioritization
[Relazione in Atti di Convegno]
Notomista, G.; Mayya, S.; Selvaggio, M.; Santos, M.; Secchi, C.
abstract
Executing multiple tasks concurrently is important in many robotic applications. Moreover, the prioritization of tasks is essential in applications where safety-critical tasks need to precede application-related objectives, in order to protect both the robot from its surroundings and vice versa. Furthermore, the possibility of switching the priority of tasks during their execution gives the robotic system the flexibility of changing its objectives over time. In this paper, we present an optimization-based task execution and prioritization framework that lends itself to the case of time-varying priorities as well as variable number of tasks. We introduce the concept of extended set-based tasks, encode them using control barrier functions, and execute them by means of a constrained-optimization problem, which can be efficiently solved in an online fashion. Finally, we show the application of the proposed approach to the case of a redundant robotic manipulator.
2020
- A Unified Architecture for Physical and Ergonomic Human–Robot Collaboration
[Articolo su rivista]
Ferraguti, Federica; Villa, Renzo; Landi, Chiara Talignani; Zanchettin, Andrea Maria; Rocco, Paolo; Secchi, Cristian
abstract
Industrial applications that involve working on and moving a heavy load or that constrain the operator to work in uncomfortable positions can take advantage of the assistance of a robotic assistant. In this paper, we propose an architecture for an ergonomic human–robot co-manipulation of objects of various shapes and weight. The object is carried by the robot and, thanks to an ergonomic planner, is positioned in the most comfortable way for the user. Furthermore, thanks to an admittance control with payload compensation, the user can easily adjust the position of the object for working on different parts of it. The proposed architecture is experimentally validated in a robotic cell including an ABB industrial robot.
2020
- Adaptive Authority Allocation in Shared Control of Robots Using Bayesian Filters
[Relazione in Atti di Convegno]
Balachandran, R.; Mishra, H.; Cappelli, M.; Weber, B.; Secchi, C.; Ott, C.; Albu-Schaeffer, A.
abstract
In the present paper, we propose a novel system-driven adaptive shared control framework in which the autonomous system allocates the authority among the human operator and itself. Authority allocation is based on a metric derived from a Bayesian filter, which is being adapted online according to real measurements. In this way, time-varying measurement noise characteristics are incorporated. We present the stability proof for the proposed shared control architecture with adaptive authority allocation, which includes time delay in the communication channel between the operator and the robot. Furthermore, the proposed method is validated through experiments and a user-study evaluation. The obtained results indicate significant improvements in task execution compared with pure teleoperation.
2020
- Augmented Reality and Robotic-Assistance for Percutaneous Nephrolithotomy
[Articolo su rivista]
Ferraguti, Federica; Minelli, Marco; Farsoni, Saverio; Bazzani, Stefano; Bonfe, Marcello; Vandanjon, Alexandre; Puliatti, Stefano; Bianchi, Giampaolo; Secchi, Cristian
abstract
2020
- Humans interacting with multi-robot systems: a natural affect-based approach
[Articolo su rivista]
Villani, V.; Capelli, B.; Secchi, C.; Fantuzzi, C.; Sabattini, L.
abstract
This paper proposes a novel human–multi-robot-system interaction approach that enjoys two main features: natural interaction and affect-based adaptation of robots behavior. Specifically, the proposed system enables interaction by means of a wrist-worn device, such as a commercial smartwatch, which allows to track user’s movements and heart activity. Thus, on the one side, the proposed system allows the user to intuitively drive the robots by establishing a natural mapping between wrist movements and robots velocity. On the other side, the system estimates user’s mental fatigue during interaction by means of the analysis of heart rate variability. The proposed interaction system adapts then the behavior of the multi-robot system when the interacting user gets overwhelmed with the interaction and control task, which is then simplified. Experimental validation is provided, to show the effectiveness of the proposed system. First, the natural and affect-based interaction are considered separately. Then, the approach is tested considering a complex realistic scenario, which is simulated in virtual reality in order to get an immersive and realistic interaction experience. The results of the experimental validation clearly show that the proposed affect-based adaptive system leads to relieving the user’s fatigue and mental workload.
2020
- Integrating model predictive control and dynamic waypoints generation for motion planning in surgical scenario
[Relazione in Atti di Convegno]
Minelli, M.; Sozzi, A.; De Rossi, G.; Ferraguti, F.; Setti, F.; Muradore, R.; Bonfe, M.; Secchi, C.
abstract
In this paper we present a novel strategy for motion planning of autonomous robotic arms in Robotic Minimally Invasive Surgery (R-MIS). We consider a scenario where several laparoscopic tools must move and coordinate in a shared environment. The motion planner is based on a Model Predictive Controller (MPC) that predicts the future behavior of the robots and allows to move them avoiding collisions between the tools and satisfying the velocity limitations. In order to avoid the local minima that could affect the MPC, we propose a strategy for driving it through a sequence of waypoints. The proposed control strategy is validated on a realistic surgical scenario.
2020
- Mutualistic and adaptive human-machine collaboration based on machine learning in an injection moulding manufacturing line
[Relazione in Atti di Convegno]
Bettoni, A.; Montini, E.; Righi, M.; Villani, V.; Tsvetanov, R.; Borgia, S.; Secchi, C.; Carpanzano, E.
abstract
This paper proposes an adaptive human-machine collaboration paradigm based on machine learning. Human-machine collaboration requires more than letting humans and machines interact according to fixed rules. A decision-maker is needed to assess production status and to activate adaptations that improve productivity and workers' well-being. The proposed solution has been tested in an injection moulding manufacturing line. By introducing a physiological monitoring system and a smart decision-maker, relief from fatigue and mental stress is pursued by adjusting the level of support offered through a cobot. Results reported a reduction of operators' physical and mental workload as well as productivity increase.
2020
- Network Robotics
[Capitolo/Saggio]
Sabattini, Lorenzo; Secchi, Cristian; Melchiorri, Claudio
abstract
2020
- Safety barrier functions and multi-camera tracking for human–robot shared environment
[Articolo su rivista]
Ferraguti, Federica; Talignani Landi, Chiara; Costi, Silvia; Bonfè, Marcello; Farsoni, Saverio; Secchi, Cristian; Fantuzzi, Cesare
abstract
A new vision in human–robot collaboration has allowed to place robots nearby human operators, working close to each other in industrial environments. As a consequence, human safety has become a dominant issue, together with production efficiency. In this paper we propose an optimization-based control algorithm that allows robots to avoid obstacles (like human operators) while minimizing the difference between the nominal acceleration input and the commanded one. Control Barrier Functions are exploited to build safety barriers around each robot link, to guarantee collision-free trajectories along the whole robot body. Human accelerations and velocities are computed by means of a bank of Kalman filters. To solve obstruction problems, two RGB-D cameras are used and the measured skeleton data are processed and merged using the mentioned bank of Kalman filters. The algorithm is implemented on an Universal Robots UR5 in order to validate the proposed approach.
2020
- Technical and Functional Validation of a Teleoperated Multirobots Platform for Minimally Invasive Surgery
[Articolo su rivista]
Leporini, Alice; Oleari, Elettra; Landolfo, Carmela; Sanna, Alberto; Larcher, Alessandro; Gandaglia, Giorgio; Fossati, Nicola; Muttin, Fabio; Capitanio, Umberto; Montorsi, Francesco; Salonia, Andrea; Minelli, Marco; Ferraguti, Federica; Secchi, Cristian; Farsoni, Saverio; Sozzi, Alessio; Bonfe, Marcello; Sayols, Narcis; Hernansanz, Albert; Casals, Alicia; Hertle, Sabine; Cuzzolin, Fabio; Dennison, Andrew; Melzer, Andreas; Kronreif, Gernot; Siracusano, Salvatore; Falezza, Fabio; Setti, Francesco; Muradore, Riccardo
abstract
2020
- Teleoperation of Multi-Robot Systems to Relax Topological Constraints
[Relazione in Atti di Convegno]
Sabattini, L.; Capelli, B.; Fantuzzi, C.; Secchi, C.
abstract
Multi-robot systems are able to achieve common objectives exchanging information among each other. This is possible exploiting a communication structure, usually modeled as a graph, whose topological properties (such as connectivity) are very relevant in the overall performance of the multirobot system. When considering mobile robots, such properties can change over time: robots are then controlled to preserve them, thus guaranteeing the possibility, for the overall system, to achieve its goals. This, however, implies limitations on the possible motion patterns of the robots, thus reducing the flexibility of the overall multi-robot system. In this paper we introduce teleoperation as a means to reduce these limitations, allowing temporary violations of topological properties, with the aim of increasing the flexibility of the multi-robot system.
2020
- Wearable devices for the assessment of cognitive effort for human-robot interaction
[Articolo su rivista]
Villani, Valeria; Righi, Massimiliano; Sabattini, Lorenzo; Secchi, Cristian
abstract
This paper is motivated by the need of assessing cognitive effort in affective robotics. In this context, the ultimate goal is that of assessing the mental state while the subject is interacting with a robotic system, by gathering implicit and objective information unobtrusively. To this end, we focus on wearable devices that do not affect the interaction of a human with a robot. In particular, we consider some commercial multi-purpose wearable devices, such as an armband, a smartwatch and a chest strap, and compare them in terms of accuracy in detecting cognitive effort. In an experiment setting, thirty participants were exposed to an increase in their cognitive effort by means of standard cognitive tests. Mental fatigue was estimated by measuring cardiac activity, in terms of heart rate and heart rate variability. The results have shown that the analysis of heart rate variability measured by the chest strap provides the most accurate detection of cognitive effort. Nevertheless, also measurements by the armband are sensitive to cognitive effort.
2019
- A General Approach to Natural Human-Robot Interaction
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Villani, Valeria; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper proposes a scheme for letting a human interact with a generic robot in a natural manner. Based on the concept of natural user interfaces, the proposed methods exploit recognition of the users’ forearm motion to produce commands for the robotic system. High-level commands are provided based on gesture recognition, and velocity commands are computed for the robot by mapping, in a natural manner, the motion of the user’s forearm. The method is proposed in a general manner, and is then instantiated considering two different robotic systems, namely a quadrotor and a wheeled mobile robot. Usability of the system is evaluated with experiments involving users.
2019
- A Methodology for Comparative Analysis of Collaborative Robots for Industry 4.0
[Relazione in Atti di Convegno]
Ferraguti, F.; Pertosa, A.; Secchi, C.; Fantuzzi, C.; Bonfe, M.
abstract
Collaborative robots are one of the key drivers in Industry 4.0 and they have evolved considerably since the last decades of the 20th century. With respect to the industrial robots, collaborative robots are more productive, flexible, versatile and safer. In the recent years, many industrial robot producers and startups entered the segment of collaborative robots. In this paper, we propose a methodology for developing a comparative analysis of the collaborative robots currently available in the market. The goal of the paper is to provide a framework for allowing the benchmarking, based on common robot parameters and standardized experiments that can be performed with the robot under investigation. An experimental technological review of three different collaborative robots is provided, to show how the methodology can be applied in real cases.
2019
- A passivity-based strategy for manual corrections in human-robot coaching
[Articolo su rivista]
Landi, Chiara Talignani; Ferraguti, Federica; Fantuzzi, Cesare; Secchi, Cristian
abstract
In recent years, new programming techniques have been developed in the human-robot collaboration (HRC) field. For example, walk-through programming allows to program the robot in an easy and intuitive way. In this context, a modification of a portion of the trajectory usually requires the teaching of the path from the beginning. In this paper we propose a passivity-based method to locally change a trajectory based on a manual human correction. At the beginning the robot follows the nominal trajectory, encoded through the Dynamical Movement Primitives, by setting high control gains. When the human grasps the end-effector, the robot is made compliant and he/she can drive it along the correction. The correction is optimally joined to the nominal trajectory, resuming the path tracking. In order to avoid unstable behaviors, the variation of the control gains is performed exploiting energy tanks, preserving the passivity of the interaction. Finally, the correction is spatially fixed so that a variation in the boundary conditions (e.g., the initial/final points) does not affect the modification.
2019
- A variable admittance control strategy for stable physical human–robot interaction
[Articolo su rivista]
Ferraguti, Federica; Talignani Landi, Chiara; Sabattini, Lorenzo; Bonfè, Marcello; Fantuzzi, Cesare; Secchi, Cristian
abstract
Admittance control allows a desired dynamic behavior to be reproduced on a non-backdrivable manipulator and it has been widely used for interaction control and, in particular, for human–robot collaboration. Nevertheless, stability problems arise when the environment (e.g. the human) the robot is interacting with becomes too stiff. In this paper, we investigate the stability issues related to a change of stiffness of the human arm during the interaction with an admittance-controlled robot. We propose a novel method for detecting the rise of instability and a passivity-preserving strategy for restoring a stable behavior. The results of the paper are validated on two robotic setups and with 50 users performing two tasks that emulate industrial operations.
2019
- Aerial physical interaction via IDA-PBC
[Articolo su rivista]
Yüksel, Burak; Secchi, Cristian; Bülthoff, Heinrich H.; Franchi, Antonio
abstract
This paper proposes the use of a novel control method based on interconnection and damping assignment–passivity-based control (IDA-PBC) in order to address the aerial physical interaction (APhI) problem for a quadrotor unmanned aerial vehicle (UAV). The apparent physical properties of the quadrotor are reshaped in order to achieve better APhI performances, while ensuring the stability of the interaction through passivity preservation. The robustness of the IDA-PBC method with respect to sensor noise is also analyzed. The direct measurement of the external wrench, needed to implement the control method, is compared with the use of a nonlinear Lyapunov-based wrench observer and advantages/disadvantages of both methods are discussed. The validity and practicability of the proposed APhI method is evaluated through experiments, where for the first time in the literature, a lightweight all-in-one low-cost force/torque (F/T) sensor is used onboard of a quadrotor. Two main scenarios are shown: a quadrotor responding to external disturbances while hovering (physical human–quadrotor interaction), and the same quadrotor sliding with a rigid tool along an uneven ceiling surface (inspection/painting-like task).
2019
- An energy-shared two-layer approach for multi-master-multi-slave bilateral teleoperation systems
[Relazione in Atti di Convegno]
Minelli, M.; Ferraguti, F.; Piccinelli, N.; Muradore, R.; Secchi, C.
abstract
In this paper, a two-layer architecture for the bilateral teleoperation of multi-arms systems with communication delay is presented. We extend the single-master-single-slave two layer approach proposed in [1] by connecting multiple robots to a single energy tank. This allows to minimize the conservativeness due to passivity preservation and to increment the level of transparency that can be achieved. The proposed approach is implemented on a realistic surgical scenario developed within the EU-funded SARAS project.
2019
- Cognitive Robotic Architecture for Semi-Autonomous Execution of Manipulation Tasks in a Surgical Environment
[Relazione in Atti di Convegno]
De Rossi, Giacomo; Minelli, Marco; Sozzi, Alessio; Piccinelli, Nicola; Ferraguti, Federica; Setti, Francesco; Bonfe, Marcello; Secchi, Cristian; Muradore, Riccardo
abstract
2019
- Communication Through Motion: Legibility of Multi-Robot Systems
[Relazione in Atti di Convegno]
Capelli, B.; Secchi, C.; Sabattini, L.
abstract
The interaction between a user and a multi-robot system in a shared environment is a relatively uncharted topic. But, as these types of systems will increase in the future years, an efficient way of communication is necessary. To this aim, it is interesting to discover if a multi-robot system can communicate its intentions exploiting only some motion-variables, which are characteristics of the motion of the robots. This study is about the legibility of a multi-robot system: In particular, we focus on the influence of these motion-variables on the legibility of more than one group of robots that move in a shared environment with the user. These motion-variables are: Trajectory, dispersion and stiffness. They are generally used to define the motion of a group of mobile robots. Trajectory and dispersion were found relevant for the correctness of the communication between the user and the multi-robot system, while stiffness was found relevant for the rapidity of communication. The analysis of the influence of the motion-variables was carried out with an ANOVA (analysis of variance) based on a series of data coming from an experimental campaign conducted in a virtual reality set-up.
2019
- Coordination of multiple AGVs: a quadratic optimization method
[Articolo su rivista]
Digani, Valerio; Hsieh, M. Ani; Sabattini, Lorenzo; Secchi, Cristian
abstract
This paper presents an optimization strategy to coordinate a fleet of Automated Guided Vehicles (AGVs) traveling on ad-hoc pre-defined roadmaps. Specifically, the objective is to maximize traffic throughput of AGVs navigating in an automated warehouse by minimizing the time AGVs spend negotiating complex traffic patterns to avoid collisions with other AGVs. In this work, the coordination problem is posed as a Quadratic Program where the optimization is performed in a centralized manner. The proposed method is validated by means of simulations and experiments for different industrial warehouse scenarios. The performance of the proposed strategy is then compared with a recently proposed decentralized coordination strategy that relies on local negotiations for shared resources. The results show that the proposed coordination strategy successfully maximizes vehicle throughput and significantly minimizes the time vehicles spend negotiating traffic under different scenarios.
2019
- Decentralized state estimation for the control of network systems
[Articolo su rivista]
Boem, Francesca; Sabattini, Lorenzo; Secchi, Cristian
abstract
The paper proposes a decentralized state estimation method for the control of network systems, where a cooperative objective has to be achieved. The nodes of the network are partitioned into independent nodes, providing the control inputs, and dependent nodes, controlled by local interaction laws. The proposed state estimation algorithm allows the independent nodes to estimate the state of the dependent nodes in a completely decentralized way. To do that, it is necessary for each independent node of the network to estimate the control input components computed by the other independent nodes, without requiring communication among the independent nodes. The decentralized state estimator, including an input estimator, is developed and the convergence properties are studied. Simulation results show the effectiveness of the proposed approach.
2019
- Energy optimization for a robust and flexible interaction control
[Relazione in Atti di Convegno]
Secchi, C.; Ferraguti, F.
abstract
The possibility of adapting online the way a robot interacts with the environment is becoming more and more important. In this paper we introduce the tank based admittance controller. We show that all the admittance controllers can be modeled as an energy optimization problem and then we introduce a novel admittance control strategy that allows to change online the interactive behavior while preserving a stable interaction with the environment. The effectiveness of the proposed architecture is experimentally validated.
2019
- Multi-rate tracking control for a space robot on a controlled satellite: A passivity-based strategy
[Articolo su rivista]
De Stefano, Marco; Mishra, Hrishik; Balachandran, Ribin; Lampariello, Roberto; Ott, Christian; Secchi, Cristian
abstract
In this letter we design a novel control strategy for a space manipulator operating on a controlled base. The proposed controllers resolve the tracking of the end-effector and the regulation of the base. In particular, we focus on the effects due to the different sampling rates of the manipulator and the base controllers which can generate stability issues. These effects are analysed from an energetic perspective and passivity-based controllers are designed for the base and the manipulator to avoid instability. The method is validated with simulations and experiments on a robotic facility, the OOS-Sim.
2019
- Prediction of Human Arm Target for Robot Reaching Movements
[Relazione in Atti di Convegno]
Landi, Chiara Talignani; Cheng, Yujiao; Ferraguti, Federica; Bonfe, Marcello; Secchi, Cristian; Tomizuka, Masayoshi
abstract
2019
- Safety barrier functions for human-robot interaction with industrial manipulators
[Relazione in Atti di Convegno]
Landi, C. T.; Ferraguti, F.; Costi, S.; Bonfe, M.; Secchi, C.
abstract
A change in the paradigm of Human-Robot Interaction has allowed to place robots nearby human operators, creating shared working environments. Industrial manipulators are becoming human helpers in different industrial tasks. As a consequence, human safety plays a leading role in the development of control algorithms. In this paper we propose an optimization-based algorithm that allows to avoid obstacles while minimizing the difference between the nominal acceleration input and the commanded one. Safety barriers are built around the robot links and allow to generate collision-free movements of the whole robot body. The algorithm is implemented on an Universal Robots UR5 in order to validate the proposed approach.
2019
- TIREBOT: A collaborative robot for the tire workshop
[Articolo su rivista]
Levratti, Alessio; Riggio, Giuseppe; Fantuzzi, Cesare; De Vuono, Antonio; Secchi, Cristian
abstract
Collaborative robots allow to relieve humans from tedious and/or tiring tasks while leaving to the operator high-level activities, where their expertise is needed. In this paper the mechanical design and the collaborative control of TIREBOT, a robotic assistant helping tire workshop operators in the wheel replacement process, is illustrated. The effectiveness of TIREBOT is validated in a real tire-workshop. Furthermore, the possibility of using TIREBOT as an autonomous personal forklift has been validated in an industrial scenario.
2019
- Tele-echography using a two-layer teleoperation algorithm with energy scaling
[Relazione in Atti di Convegno]
Sartori, E.; Tadiello, C.; Secchi, C.; Muradore, R.
abstract
Performing ultrasound procedures from a remote site is a challenging task since both a stable behavior, for the safety of the patient, and a high-level of usability, to exploit the sonographer's expertise, need to be guaranteed. Furthermore, a teleoperation system that provides such requirements has to deal with communication delays as well. To address this issue, we use the two-layer algorithm: a passivity-based bilateral teleoperation architecture able to guarantee stability despite unknown and time-varying delay. Its flexibility allows to implement different kinds of control laws. In a Tele-Echography system, the slave manipulator has to apply significant forces needed by the procedure whereas the haptic device at the master side should be very light to avoid tiring the operator. Therefore, the energy needed by these two robots to perform their movements is very different and the energy injected into the system by the operator is often not sufficient to implement the desired action at the slave side. Methods to overcome this problem require to perfectly know the dynamical models of the robots. The solution proposed in this paper does not require such knowledge and is based on properly scaling the energy exchanged between the master and the slave side. We show the effectiveness of this approach in a real setup using a TOUCH haptic device and a WAM Barrett robot holding an ultrasound probe.
2019
- Teleoperation of a Multi-robot System with Adjustable Dynamic Parameters
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Fantuzzi, Cesare; Secchi, Cristian
abstract
Teleoperation of a Multi-Robot System with Adjustable Dynamic Parameters
2019
- Time-delay Compensation Using Energy Tank for Satellite Dynamics Robotic Simulators
[Relazione in Atti di Convegno]
Stefano, Marco De; Vezzadini, Luca; Secchi, Cristian
abstract
In this work we present a novel approach which compensates the destabilising effects of the time delay intrinsic in the control loop of an admittance-controlled robot employed for satellite dynamics simulation. The method is based on an energy storing element, the tank, which is exploited by the controller to preserve the passivity of the system and to avoid instability. Furthermore, we compare the performance of the proposed method with existing energy-based approaches, namely time-domain-passivity and wave variable transformation. The performance comparison and robustness of the methods are analysed in a Montecarlo simulation and validated experimentally.
2019
- Understanding Multi-Robot Systems: on the Concept of Legibility
[Relazione in Atti di Convegno]
Capelli, Beatrice; Villani, Valeria; Secchi, Cristian; Sabattini, Lorenzo
abstract
2018
- A Framework for Affect-Based Natural Human-Robot Interaction
[Relazione in Atti di Convegno]
Villani, Valeria; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we present a general framework for affective human-robot interaction that allows users to intuitively interact with a robot and takes into account their mental fatigue, thus simplifying the task or providing assistance when the user feels stressed. Interaction with the robot is achieved by naturally mapping user's forearm motion, detected with a smartwatch, into robot's motion. High-level commands can be provided by means of gestures. An approach based on affective robotics is used to adapt the level of robot's autonomy to the cognitive workload of the user. User's mental fatigue is detected from the analysis of heart rate, also measured by the smartwatch. The framework is general and can be applied to different robotic systems. In this paper, we consider its experimental validation on a wheeled mobile robot.
2018
- A Low-Cost Navigation Strategy for Yield Estimation in Vineyards
[Relazione in Atti di Convegno]
Riggio, Giuseppe; Fantuzzi, Cesare; Secchi, Cristian
abstract
Accurate yield estimation is very important for improving the vineyard management, the quality of the grapes and the health of the vines. The most common systems use RGB image processing for achieving a good estimation. In order to collect images, robots or farming vehicles can be equipped with a RGB camera. In this paper, we propose a low-cost autonomous system which can navigate through a vineyard while collecting grape pictures in order to provide a yield estimation. Our system uses only a laser scanner to detect the row and follows it until its end, then it navigates towards the next one, exploiting the knowledge of the vineyard. The navigation algorithm was tested both in simulation and in a real environment with good results. Furthermore, a yield estimation of two different grape varieties is presented.
2018
- A Passivity-Based Strategy for Coaching in Human-Robot Interaction
[Relazione in Atti di Convegno]
Landi, Chiara Talignani; Ferraguti, Federica; Fantuzzi, Cesare; Secchi, Cristian
abstract
In order to make robot programming more easy and immediate, walk-through programming techniques can be exploited. However, a modification of a portion of the trajectory usually means to execute the path from the beginning. In this paper we propose a passivity-based framework to modify the trajectory online, manually driving the robot throughout the desired correction. The system follows the initial trajectory, encoded with Dynamical Movement Primitives, by setting high gains in the admittance control. When the human operator grabs the end-effector, the robot becomes compliant and the user can easily teach the desired correction, until he/she releases it at the end of the modification. Finally, the correction is optimally joined to the initial trajectory, restarting the path tracking. To avoid unsafe behaviors, the variation of the admittance parameters is performed exploiting energy tanks, in order to preserve the passivity of the interaction.
2018
- An Energy-Based Approach for the Multi-Rate Control of a Manipulator on an Actuated Base
[Relazione in Atti di Convegno]
De Stefano, Marco; Balachandran, Ribin; Giordano, Alessandro M.; Ott, Christian; Secchi, Cristian
abstract
In this paper we address the problem of controlling a robotic system mounted on an actuated floating base for space applications. In particular, we investigate the stability issues due to the low rate of the base control unit. We propose a passivity-based stabilizing controller based on the time domain passivity approach. The controller uses a variable damper regulated by a designed energy observer. The effectiveness of the proposed strategy is validated on a base-manipulator multibody simulation.
2018
- Controlling the interaction of a multi-robot system with external entities
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we consider a multi-robot system
that shares the environment with external entities, and we
propose a methodology for controlling the interaction with
them. In particular, we consider the problem of achieving
a desired dynamic interaction model, in such a way that
the multi-robot system exchanges desired forces with external
entities. This is obtained by introducing local deformations of
the coupling actions among the robots. The proposed method
ensures preservation of the passivity property, which provides
safety guarantees in the interaction with the (possibly poorly
known) external entities.
2018
- Distributed Laplacian Eigenvalue and Eigenvector Estimation in Multi-robot Systems
[Relazione in Atti di Convegno]
Zareh, Mehran; Sabattini, Lorenzo; Secchi, Cristian
abstract
Distributed Laplacian Eigenvalue and Eigenvector Estimation in Multi-robot Systems
2018
- On the Use of Energy Tanks for Multi-Robot Interconnection
[Relazione in Atti di Convegno]
Riggio, Giuseppe; Fantuzzi, Cesare; Secchi, Cristian
abstract
In multi-robot systems passive interconnections among agents are often exploited to achieve a desired and robustly stable cooperative behavior. Nevertheless, the passivity constraint limits the kinds of behaviors that can be achieved. In this paper, we exploit the concept of energy tank for building a novel generalized interconnection that allows to impose any kind of dynamic coupling between two passive systems in a flexible way while preserving the passivity of the overall coupled system. The proposed strategy is validated by simulations and experiments.
2018
- Passivity preserving force scaling for enhanced teleoperation of multirobot systems
[Articolo su rivista]
Sabattini, Lorenzo; Secchi, Cristian; Capelli, Beatrice; Fantuzzi, Cesare
abstract
In this letter, we address the problem of teleoperating a multirobot system, and we propose a methodology for letting the user teleoperate the group of robots according to some desired dynamic behavior. Specifically, we propose a novel methodology for the teleoperation of multirobot systems, where a local control action and interrobot relationships are tuned in order to reduce their effect on the force feedback perceived by the operator. The proposed methodology is developed guaranteeing preservation of the passivity property. The effectiveness of the proposed teleoperation scheme is validated experimentally, on real robots and in a virtual reality environment.
2018
- Port Hamiltonian Modeling of a Cable Driven Robot
[Relazione in Atti di Convegno]
Schenk, Christian; Yüksel, Burak; Secchi, Cristian; Bülthoff, Heinrich H.
abstract
In this paper we present a generic Port-Hamiltonian (PH) model that includes cable dynamics (in particular elasticity and couplings with the platform and all cables among each other) of a cable-driven parallel robot (CDPR), which is used as a motion simulator. Moreover we consider changes in the cable parameters, i.e. it’s elasticity, mass and length when the cables are wound/unwound from the winches. To the best of our knowledge nobody considered such a detailed and generic model of a CDPR in PH structure before. Since motion simulators are built to mimic systems with different physical properties, PH modeling can pave the way for physics-shaping controllers.
2018
- Real-time identification of robot payload using a multirate quaternion-based kalman filter and recursive total least-squares
[Relazione in Atti di Convegno]
Farsoni, Saverio; Landi, Chiara Talignani; Ferraguti, Federica; Secchi, Cristian; Bonfe, Marcello
abstract
The paper describes an estimation and identification procedure that allows to reconstruct the inertial parameters of a rigid load attached to the end-effector of an industrial manipulator. In particular, the proposed method adopts a multirate quaternion-based Kalman filter, fusing measurements obtained from robot kinematics and inertial sensors at possibly different sampling frequencies, to estimate linear accelerations and angular velocities/accelerations of the load. Then, a recursive total least-squares (RTLS) process is executed to identify the load parameters. Both steps of the estimation and identification procedure are performed in real-time, without the need for offline post-processing of measured data.
2018
- Relieving operators’ workload: Towards affective robotics in industrial scenarios
[Articolo su rivista]
TALIGNANI LANDI, Chiara; Villani, Valeria; Ferraguti, Federica; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper proposes a novel approach based on affective robotics that can be applied to industrial applications. Considering a human-robot interaction task, we propose to analyze the mental workload of the operator, and subsequently adapt the behavior of the robotic system, introducing assistive technologies. These technologies would prevent the performances deterioration caused by the human stress, helping him/her only when needed and decreasing the user's mental workload. This represents a general methodology, which can be applied to several industrial applications, leading to increase the overall performances of human-robot interaction exploiting principles of human-centered design. As a case study, we consider a teleoperation task, where virtual fixtures are utilized as an assistive technology. The stress of the operator is monitored in terms of heart rate variability, measured by means of a wearable sensor tied at the operator's wrist. Experimental validation of the proposed architecture is performed on a group of 15 users that teleoperate an industrial robot for performing a pick and place task.
2018
- Shaping the force feedback by dynamic scaling in the teleoperation of multi-robot systems
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Fantuzzi, Cesare; Secchi, Cristian
abstract
In passivity based bilateral teleoperation of multi-robot systems the coupling among
the robots produces unwanted dynamic effects that deteriorates the force fed back to the user.
In this paper we propose a passivity based dynamic scaling strategy for compensating these
disturbing terms. The effectiveness of the proposed methodology is experimentally validated.
2018
- Survey on Human-Robot Interaction for Robot Programming in Industrial Applications
[Capitolo/Saggio]
Villani, Valeria; Pini, Fabio; Leali, Francesco; Secchi, Cristian; Fantuzzi, Cesare
abstract
The recent trends in modern industry highlight an increasing use of robots for a wide range of applications, which span from established manufacturing operations to novel tasks characterized by a close collaboration with the operators. Although human-robot collaboration allows to relieve operators of exhausting works, an effective collaboration requires a straightforward interaction to foster the use of robot assistants. This paper provides a comprehensive survey on human-robot interaction approaches and related interfaces addressed to robot programming. An overview of on-line and off-line robot programming techniques is first presented. Then, novel intuitive interaction means, such as those based on multi-modal interaction, virtual and augmented reality, are considered. The paper aims at pointing out that collaborative robotics can effectively reduce operator's physical workload if easy to use interfaces for robot programming are provided.
2018
- Survey on human-robot collaboration in industrial settings: Safety, intuitive interfaces and applications
[Articolo su rivista]
Villani, Valeria; Pini, Fabio; Leali, Francesco; Secchi, Cristian
abstract
Easy-to-use collaborative robotics solutions, where human workers and robots share their skills, are entering the market, thus becoming the new frontier in industrial robotics. They allow to combine the advantages of robots, which enjoy high levels of accuracy, speed and repeatability, with the flexibility and cognitive skills of human workers. However, to achieve an efficient human-robot collaboration, several challenges need to be tackled. First, a safe interaction must be guaranteed to prevent harming humans having a direct contact with the moving robot. Additionally, to take full advantage of human skills, it is important that intuitive user interfaces are properly designed, so that human operators can easily program and interact with the robot. In this survey paper, an extensive review on human-robot collaboration in industrial environment is provided, with specific focus on issues related to physical and cognitive interaction. The commercially available solutions are also presented and the main industrial applications where collaborative robotic is advantageous are discussed, highlighting how collaborative solutions are intended to improve the efficiency of the system and which the open issue are.
2018
- The PAN-Robots Project: Advanced Automated Guided Vehicle Systems for Industrial Logistics
[Articolo su rivista]
Sabattini, Lorenzo; Aikio, Mika; Beinschob, Patric; Boehning, Markus; Cardarelli, Elena; Digani, Valerio; Krengel, Annette; Magnani, Massimiliano; Mandici, Szilard; Oleari, Fabio; Reinke, Christoph; Ronzoni, Davide; Stimming, Christian; Varga, Robert; Vatavu, Andrei; Castells Lopez, Sergi; Fantuzzi, Cesare; Mayra, Aki; Nedevschi, Sergiu; Secchi, Cristian; Fuerstenberg, Kay
abstract
In modern manufacturing plants, automation is widely adopted in the production phases, which leads to achieving a high
level of productivity and efficiency. However, the same level of automation is generally not achieved in logistics, that is
typically performed by human operators, and manually driven vehicles. In fact, even though Automated Guided Vehicles
(AGVs) have been used for a few decades for goods transportation in industrial environments [1], they do not represent
a widespread solution yet, and are typically applied only in specific scenarios.
2017
- A Natural Infrastructure-Less Human–Robot Interaction System
[Articolo su rivista]
Villani, Valeria; Sabattini, Lorenzo; Riggio, Giuseppe; Secchi, Cristian; Minelli, Marco; Fantuzzi, Cesare
abstract
This letter introduces a novel methodology for letting a user interact with a robotic system in a natural manner. The main idea is that of defining an interaction system that does not require any specific infrastructure or device but relies on commonly utilized objects while leaving the user’s hands free. Specifically, we propose to utilize a smartwatch (or any commercial sensorized wristband) for recognizing the motion of the user’s forearm. This is achieved by measuring accelerations and angular velocities, which are then elaborated for recognizing gestures and for defining velocity commands for the robot. The proposed interaction system is evaluated experimentally with different users controlling a semiautonomous quadrotor. Results show that the usability and effective- ness of the proposed natural interaction system provide significant improvement in the human–robot interaction experience.
2017
- A passive integration strategy for rendering rotational rigid-body dynamics on a robotic simulator
[Relazione in Atti di Convegno]
De Stefano, Marco; Artigas, Jordi; Secchi, Cristian
abstract
This paper proposes a passive and explicit integrator for simulating a rotational rigid-body dynamics rendered by a robot. Considering the Euler integration method, active energy terms are identified. These sources of energy are due to the external torque and the coupled dynamics which can lead to a non-physical behavior of the simulated dynamics. The proposed method dissipates this energy using a variable damper regulated by an energy observer. The new algorithm guarantees not only passivity but also a consistent energetic integration. The integration method is sustained by simulations and tested on a real-time hardware-in-the-loop simulator.
2017
- Achieving the desired dynamic behavior in multi-robot systems interacting with the environment
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we consider the problem of controlling the dynamic behavior of a multi-robot system while interacting with the environment. In particular, we propose a general methodology that, by means of locally scaling interrobot coupling relationships, leads to achieving a desired interactive behavior. The proposed method is shown to guarantee passivity preservation, which ensures a safe interaction. The performance of the proposed methodology is evaluated in simulation, over large-scale multi-robot systems.
2017
- Admittance control parameter adaptation for physical human-robot interaction
[Relazione in Atti di Convegno]
Landi, Chiara Talignani; Ferraguti, Federica; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In physical human-robot interaction, the coexistence of robots and humans in the same workspace requires the guarantee of a stable interaction, trying to minimize the effort for the operator. To this aim, the admittance control is widely used and the appropriate selection of the its parameters is crucial, since they affect both the stability and the ability of the robot to interact with the user. In this paper, we present a strategy for detecting deviations from the nominal behavior of an admittance-controlled robot and for adapting the parameters of the controller while guaranteeing the passivity. The proposed methodology is validated on a KUKA LWR 4+.
2017
- An assisted bilateral control strategy for 3D pose estimation of visual features
[Relazione in Atti di Convegno]
Battilani, Nicola; Spica, Riccardo; Giordano, Paolo Robuffo; Secchi, Cristian
abstract
Teleoperating a quadrotor equipped with a monocular camera for exploring a wide area in search of something has become a common practice in many application scenarios (e.g. search and rescue). In order to efficiently plan operations, estimating the 3D pose of a point of interest is as important as detecting it. In this paper we propose a novel bilateral teleoperation architecture where an estimation scheme is exploited for recovering the position of a set of visual features while an operator steers the motion of the quadrotor UAV. The operator acts on a force-feedback master device that produces force cues meant to suggest where to drive the quadrotor for improving the convergence rate of the estimation process. The effectiveness of the proposed teleoperation strategy is validated by means of hardware in the loop simulations.
2017
- Collision avoidance for multiple Lagrangian dynamical systems with gyroscopic forces
[Articolo su rivista]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
This article introduces a novel methodology for dealing with collision avoidance for groups of mobile robots. In particular, full dynamics are considered, since each robot is modeled as a Lagrangian dynamical system moving in a three-dimensional environment. Gyroscopic forces are utilized for defining the collision avoidance control strategy: This kind of forces leads to avoiding collisions, without interfering with the convergence properties of the multi-robot system's desired control law. Collision avoidance introduces, in fact, a perturbation on the nominal behavior of the system: We define a method for choosing the direction of the gyroscopic force in an optimal manner, in such a way that perturbation is minimized. Collision avoidance and convergence properties are analytically demonstrated, and simulation results are provided for validation purpose.
2017
- Compensation of Load Dynamics for Admittance Controlled Interactive Industrial Robots using a Quaternion-based Kalman Filter
[Articolo su rivista]
Farsoni, Saverio; TALIGNANI LANDI, Chiara; Ferraguti, Federica; Secchi, Cristian; Bonfè, Marcello
abstract
The paper describes a control architecture for industrial robotic applications allowing human/robot interactions, using an admittance control scheme and direct sensing of the human inputs. The aim of the proposed scheme is to support the operator of an industrial robot, equipped with a force/torque (F/T) sensor on the end-effector, during human/robot collaboration tasks involving heavy payloads carried by the robot. In these practical applications, the dynamics of the load may significatively affect the measurements of the F/T sensor. Model-based compensation of such dynamic effects requires to compute linear acceleration and angular acceleration/velocity of the load, that in this paper are estimated by means of a quaternion-based Kalman filter and assuming that the only available measurements come from the forward kinematics of the robot. Experimental results demonstrate the feasibility of the approach and its industrial applicability.
2017
- Cooperative cloud robotics architecture for the coordination of multi-AGV systems in industrial warehouses
[Articolo su rivista]
Cardarelli, Elena; Digani, Valerio; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we introduce a novel cloud robotics architecture that provides different functionalities to support enhanced coordination of groups of Automated Guided Vehicles (AGVs) used for industrial logistics. In particular, we define a cooperative data fusion system that, gathering data from different sensing sources, provides a constantly updated global live view of the industrial environment, for coordinating the motion of the AGVs in an optimized manner. In fact, local sensing capabilities are complemented with global information, thus extending the field of view of each AGV. This knowledge extension allows to support a cooperative and flexible global route assignment and local path planning in order to avoid congestion zones, obstacles reported in the global live view map and deal with unexpected obstacles in the current path. The proposed methodology is validated in a real industrial environment, allowing an AGV to safely perform an obstacle avoidance procedure.
2017
- Coordinated dynamic behaviors for multirobot systems with collision avoidance
[Articolo su rivista]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper, we propose a novel methodology for achieving complex dynamic behaviors in multirobot systems. In particular, we consider a multirobot system partitioned into two subgroups: 1) dependent and 2) independent robots. Independent robots are utilized as a control input, and their motion is controlled in such a way that the dependent robots solve a tracking problem, that is following arbitrarily defined setpoint trajectories, in a coordinated manner. The control strategy proposed in this paper explicitly addresses the collision avoidance problem, utilizing a null space-based behavioral approach: this leads to combining, in a non conflicting manner, the tracking control law with a collision avoidance strategy. The combination of these control actions allows the robots to execute their task in a safe way. Avoidance of collisions is formally proven in this paper, and the proposed methodology is validated by means of simulations and experiments on real robots.
2017
- Interacting With a Mobile Robot with a Natural Infrastructure-Less Interface
[Relazione in Atti di Convegno]
Villani, Valeria; Sabattini, Lorenzo; Riggio, Giuseppe; Levratti, Alessio; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we introduce a novel approach that enables users to interact with a mobile robot in a natural manner. The proposed interaction system does not require any specific infrastructure or device, but relies on commonly utilized objects while leaving the user’s hands free. Specifically, we propose to utilize a smartwatch (or a sensorized wristband) for recognizing the motion of the user’s forearm. Measurements of accelerations and angular velocities are exploited to recognize user’s gestures and define velocity commands for the robot. The proposed interaction system is evaluated experimentally with different users controlling a mobile robot and compared to the use of a remote control device for the teleoperation of robots. Results show that the usability and effectiveness of the proposed natural interaction system based on the use of a smartwatch provide significant improvement in the human-robot interaction experience.
2017
- Multi-robot systems implementing complex behaviors under time-varying topologies
[Articolo su rivista]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we address the problem of obtaining complex dynamic behaviors in multi-robot systems. In particular, those complex behaviors are modeled in terms of cooperative tracking of periodic setpoint trajectories. The proposed solution considers a heterogeneous group of robots: a few independent robots are used as a control input for the system, with the aim of controlling the position of the remaining robots, namely the dependent ones. The proposed control strategy explicitly considers changes in the communication topology among the robots, that lead to the definition of a switched system. In particular, these changes happen as the system evolves, since robots are equipped with finite range communication devices. A methodology is introduced for defining the system parameters in order to guarantee asymptotic stability of the switched system, thus guaranteeing the desired tracking performance, assuming that independent robots are able to measure or estimate the global state of the multi-robot system.
2017
- Natural interaction based on affective robotics for multi-robot systems
[Relazione in Atti di Convegno]
Villani, Valeria; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we introduce a novel approach
that enables users to interact with a multi-robot system in a
natural manner. Additionally, interaction adapts to the user’s
affect and stamina. To this end, we consider the use of a
smartwatch for recognizing the motion of the user’s forearm,
which is then translated in velocity commands for the robots.
A natural mapping between user’s movements and robots
commands is implemented, so that the user can intuitively drive
the robots by mimicking real-world behavior. Additionally, the
operator’s heart rate is measured, since it is a measure of mental
stress. Thus, when an increase in mental stress is detected,
the behavior of the multi-robot system is changed in order to
simplify the interaction task and relieve the user. The proposed
interaction system is tested with different users. Specifically,
the effectiveness of the natural interaction is evaluated and
compared to the use of a joypad and a haptic device. Moreover,
we preliminarily test the affective interaction approach.
2017
- Optimized simultaneous conflict-free task assignment and path planning for multi-AGV systems
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Digani, Valerio; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we address the problem of assigning a set of tasks to a set of Automated Guided Vehicles (AGVs), in a conflict-free manner. Specifically, we consider a system of multiple AGVs, moving along a predefined roadmap, and utilized for transportation of goods in automated warehouses. Sequential application of task assignment and path planning often gives rise to pathological situations, such as deadlocks, in which AGVs block each other, thus preventing tasks completion. In this paper we propose a method for assigning tasks while taking into account the subsequent path planning, encoding possible conflicts into a conflict graph, that is subsequently utilized for defining constraints of an optimization problem. Simulations are performed on maps of real industrial environments, to compare the proposed method with traditional task assignment.
2017
- Reproducing physical dynamics with hardware-in-the-loop simulators: A passive and explicit discrete integrator
[Relazione in Atti di Convegno]
De Stefano, Marco; Balachandran, Ribin; Artigas, Jordi; Secchi, Cristian
abstract
In this paper we present a passive and reliable explicit discrete integrator, which allows to preserve the energy and dynamic properties of a physical body rendered on a hardware-in-the-loop simulator. Starting from the standard Euler integrator, we identify the energy generation that results from the integration process. This energy makes the time discrete dynamics deviate from the ideal one, resulting in position drifts or stability issues. By exploiting the time domain passivity approach, the simulated dynamics is reshaped in order to preserve its physical energy properties. The proposed integration method allows precise simulation of virtual bodies on industrial robot facilities. The method has been validated in simulation and experimentally tested on the DLR OOS-SIM facility.
2017
- Safe navigation and experimental evaluation of a novel tire workshop assistant robot
[Relazione in Atti di Convegno]
Levratti, Alessio; Riggio, Giuseppe; De Vuono, Antonio; Fantuzzi, Cesare; Secchi, Cristian
abstract
This paper presents TIREBOT, a novel tire-workshop robotic co-worker that can safely move in a tire workshop and assist the operator in lifting and transporting wheels among several working stations. A safe and cooperative navigation strategy based on the concept of danger field is illustrated. Finally, TIREBOT is experimentally evaluated in a real tire-workshop and used by real operator in order to assess the usability and the effectiveness of the robot in a real operating scenario.
2017
- Semi-automated map creation for fast deployment of AGV fleets in modern logistics
[Articolo su rivista]
Beinschob, Patric; Meyer, Mark; Reinke, Christoph; Digani, Valerio; Secchi, Cristian; Sabattini, Lorenzo
abstract
Today, Automated Guided Vehicles (AGVs) still have a low market share in logistics, compared to manual forklifts. We identified one of the main bottlenecks in the rather long deployment time which involves precise 2D mapping of the plant, 3D geo-referencing of pick-up/ drop positions and the manual design of the roadmap. The long deployment time has various reasons: in state-of-the-art plant installations, designated infrastructure is still necessary for the localization; the mapping process requires highly skilled personnel; in many cases unavailable or inappropriate position information of drop points for goods must be corrected on site. Finally, the design of the roadmap, performed by expert technicians is manually optimised in a tedious process to achieve maximum flow of goods for the plant operator.
In total the setup of a plant to be ready for AGV operation is taking several months, binding highly skilled technicians and involves very time-consuming and costly on-site procedures.
Therefore, we present an approach to AGV deployment which aims to drastically reduce the time, cost and involved personnel. First, we propose the employment of a novel, industrial-ready SICK 3D laser scanning technology in order to build an accurate and consistent virtual representation of the whole warehouse environment. By utilizing suitable segmentation and processing a semantic map is generated that contains 3D geo-referenced positions as well as a 2D localization map eliminating the need for dedicated solution to 2D mapping. Second, the semantic map provides a free space map which is used as a basis for the automatic roadmap creation in order to achieve optimal flow.
So, this paper proposes an innovative methodology for obtaining, in a semi-automated manner, the map of an industrial environment where a system of multiple AGVs will be installed with less time and cost.
2017
- Variable admittance control preventing undesired oscillating behaviors in physical human-robot interaction
[Relazione in Atti di Convegno]
Landi, Chiara Talignani; Ferraguti, Federica; Sabattini, Lorenzo; Secchi, Cristian; Bonfe', Marcello; Fantuzzi, Cesare
abstract
Admittance control is a widely used approach for guaranteeing a compliant behavior of the robot in physical human-robot interaction. When an admittance-controlled robot is coupled with a human, the dynamics of the human can cause deviations from the desired behavior of the robot, mainly due to a stiffening of the human arm, and thus generate high-frequency unsafe oscillations of the robot. In this paper we present a novel methodology for detecting the rising oscillations in the human-robot interaction. Furthermore, we propose a passivity-preserving strategy to adapt the parameter of the admittance control in order to get rid of the high-frequency oscillations and, when possible, to restore the desired interaction model. A thorough experimental validation of the proposed strategy is performed on a group of 26 users performing a cooperative task.
2017
- Walk-Through Programming for Industrial Applications
[Articolo su rivista]
Ferraguti, Federica; TALIGNANI LANDI, Chiara; Secchi, Cristian; Nolli, Marco; Pesamosca, Manuel; Fantuzzi, Cesare
abstract
Collaboration between humans and robots is increasingly desired in several application domains, including the manufacturing domain. The paper describes a software control architecture for industrial robotic applications allowing human-robot cooperation during the programming phase of a robotic task. The control architecture is based on admittance control and tool dynamics compensation for implementing walk-through programming and manual guidance. Further steps to integrate this system on a real industrial setup include the robot kinematics and a socket communication that sends a binary file to the robot.
2016
- A Cognitive Robot Control Architecture for Autonomous Execution of Surgical Tasks
[Articolo su rivista]
Preda, Nicola; Ferraguti, Federica; De Rossi, Giacomo; Secchi, Cristian; Muradore, Riccardo; Fiorini, Paolo; Bonfè, Marcello
abstract
The research on medical robotics is starting to address the autonomous execution of surgical tasks, without effective intervention of humans apart from supervision and task configuration. This paper addresses the complete automation of a surgical robot by combining advanced sensing, cognition and control capabilities, developed according to rigorous assessment of surgical require- ments, formal specification of robotic system behavior and software design and implementation based on solid tools and frame- works. In particular, the paper focuses on the cognitive control architecture and its development process, based on formal modeling and verification methods as best practices to ensure safe and reliable behavior. Full implementation of the proposed architecture has been tested on an experimental setup including a novel robot specifically designed for surgical applications, but adaptable to different selected tasks (i.e. needle insertion, wound suturing).
2016
- A Probabilistic Eulerian Traffic Model for the Coordination of Multiple AGVs in Automatic Warehouses
[Articolo su rivista]
Digani, Valerio; Sabattini, Lorenzo; Secchi, Cristian
abstract
The co-ordination of multiple automated guided vehicles (AGVs) is one of the main issues to address for the implementation of an efficient autonomous warehouse. Traffic jams are highly undesirable and, therefore, the motion of the AGVs should be planned by considering the current and future state of the fleet. This letter proposes a probabilistic model of the traffic in an autonomous warehouse to predict the evolution of possibly congested areas. Such a model is then exploited for building a predictive planner that is embedded in the traffic manager recently proposed in [1] to explicitely consider the evolution of the traffic up to a given horizon and to increase the efficiency of the fleet of AGVs in terms of delivery time. The proposed traffic manager is validated by means of comparative simulations on real plants.
2016
- An optimized passivity-based method for simulating satellite dynamics on a position controlled robot in presence of latencies
[Relazione in Atti di Convegno]
De Stefano, Marco; Artigas, Jordi; Secchi, Cristian
abstract
This paper introduces a performance oriented method for simulating stable free-floating satellite dynamics on a position controlled robot. Intrinsic latencies found in robot controllers, i.e. between input and output data, are known to produce stability issues and performance degradation. These issues are even more apparent during contact phases, where impact dynamics play a major role. The approach presented in this paper guarantees stability through passivity and preserves the performance through the use of an optimal damping. The energy produced by delays found in the closed loop system is monitored and dissipated when necessary. In order to implement the dynamics accurately, the damping process is formulated as an optimization problem. Thus, over-dissipation can be avoided and the system becomes less conservative. Performance and effectiveness of the method are shown in simulation and verified experimentally on a position controlled seven degrees of freedom Light Weight Robot equipped with a force-torque sensor at the end-effector.
2016
- Catching the wave: A transparency oriented wave based teleoperation architecture
[Relazione in Atti di Convegno]
Secchi, Cristian; Ferraguti, Federica; Fantuzzi, Cesare
abstract
Wave variables are a very popular approach for dealing with communication delay in bilateral teleoperation because of their effectiveness and of their simplicity. Nevertheless, the inherent dynamics of wave based communication channels is often deleterious for the transparency of the teleoperation system. Recently proposed architectures like TDPN, PSPM and two layers approach allow to achieve a high transparency at the price of a complex architecture, with some parameters to tune empirically. In this paper we propose a novel wave based architecture that blends the high performance that can be achieved by recently proposed architectures with the simplicity of wave based bilateral teleoperation.
2016
- Coordinated motion for multi-robot systems under time varying communication topologies
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Lotti, Marco; Fantuzzi, Cesare
abstract
This paper introduces a control strategy for obtaining cooperative tracking of periodic setpoint trajectories in multi-robot systems. A heterogeneous group of robots is considered: a few independent robots are used as a control input for the system, with the aim of controlling the position of the remaining robots, namely the dependent ones. The control strategy presented in this paper explicitly considers changes in the communication topology among the robots. These changes happen as the system evolves, since robots are equipped with finite range communication devices.
2016
- Decentralized biconnectivity conditions in multi-robot systems
[Relazione in Atti di Convegno]
Zareh, Mehran; Sabattini, Lorenzo; Secchi, Cristian
abstract
The network connectivity in a group of cooperative robots can be easily broken if one of them loses its connectivity with the rest of the group. In case of having robustness with respect to one-robot failure, the communication network is termed biconnected. In simple words, to have a biconnected network graph, we need to prove that no articulation point exists. We propose a decentralized approach that provides sufficient conditions for biconnectivity of the network, and we prove that these conditions are related to the third smallest eigenvalue of the Laplacian matrix. Data exchange among the robots is supposed to be neighbor-to-neighbor.
2016
- Decentralized fault diagnosis for heterogeneous multi-agent systems
[Relazione in Atti di Convegno]
Boem, Francesca; Sabattini, Lorenzo; Secchi, Cristian
abstract
The paper proposes a decentralized method for fault detection and isolation in heterogeneous multi-agents systems. The agents are partitioned into independent nodes, providing the control inputs and monitoring the system, and dependent nodes, controlled by local interaction laws and subject to faults. The approach uses a decentralized state estimation algorithm allowing the independent nodes to estimate both the state of the dependent nodes and the control input components computed by the other independent nodes, in a completely decentralized way, without requiring communication among the independent nodes. Suitable detection and isolation residuals and thresholds are derived. Detectability and isolability sufficient conditions are provided. Simulation results show the effectiveness of the proposed approach.
2016
- Enforcing biconnectivity in multi-robot systems
[Relazione in Atti di Convegno]
Zareh Eshghdoust, Mehran; Sabattini, Lorenzo; Secchi, Cristian
abstract
Connectivity maintenance is an essential task in multi-robot systems and it has received a considerable attention during the last years. However, a connected system can be broken into two or more subsets simply if a single robot fails. Then, a more robust communication can be achieved if the network connectivity is guaranteed in the case of one-robot failures. The resulting network is called biconnected. In [1] we presented a criterion for biconnectivity check, which basically determines a lower bound on the third-smallest eigenvalue of the Laplacian matrix. In this paper we introduce a decentralized gradient-based protocol to increase the value of the third-smallest eigenvalue of the Laplacian matrix, when the biconnectivity check fails. We also introduce a decentralized algorithm to estimate the eigenvectors of the Laplacian matrix, which are used for defining the gradient. Simulations show the effectiveness of the theoretical findings.
2016
- Hierarchical coordination strategy for multi-AGV systems based on dynamic geodesic environment partitioning
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Digani, Valerio; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we consider the problem of coordinating the motion of a group of Automated Guided Vehicles (AGVs) utilized in industrial environments for logistics operations. In particular, we consider a hierarchical coordination strategy, where the environment is partitioned into sectors: coordination on the top layer defines the sequence of sectors to be traveled, while coordination on the bottom layer deals with traffic management inside each sector. In this paper we introduce a novel partitioning algorithm, that defines the sectors in a dynamic manner, taking into account both the shape of the (generally non-convex) environment, and the current distribution of the AGVs. This is achieved exploiting a clustering algorithm, and subsequently defining the sectors based on the geodesic distance.
2016
- Metodo per il trattamento superficiale di un manufatto
[Brevetto]
Fantuzzi, Cesare; Secchi, Cristian; Ferraguti, Federica; TALIGNANI LANDI, Chiara; Noli, Marco
abstract
Secondo la presente invenzione vengono un metodo ed un impianto per il trattamento superficiale secondo quanto licitato nelle rivendicazioni indipendenti che seguono e, preferibilmente, in una qualsiasi delle rivendicazioni dipendenti direttamente o indirettamente dalle rivendicazioni indipendenti.
Nel presente testo per “coppia” si intende “momento di una forza” (torque) o comunque un’altra grandezza contenente il (più precisamente, funzione del) momento di una forza. “Momento di una forza” (o “momento meccanico”) ha il suo comune significato di attitudine di una forza ad imprimere una rotazione ad un corpo rigido attorno ad un punto (nel piano) o ad un asse (nello spazio) quando questa non è applicata al suo centro di massa.
Nel presente testo per “forza” si intende anche (oltre al significato dato normalmente a questo termine) un’altra grandezza contenente la (più precisamente, funzione della) forza. Secondo alcune forme d’attuazione, per “forza” si intende forza secondo il suo normale significato.
2016
- Multi-AGV systems in shared industrial environments: Advanced sensing and control techniques for enhanced safety and improved efficiency
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Cardarelli, Elena; Digani, Valerio; Secchi, Cristian; Fantuzzi, Cesare
abstract
This chapter describes innovative sensing technologies and control techniques that aim at improving the performance of groups of automated guided vehicles (AGVs) used for logistics operations in industrial environments. We explicitly consider the situation where the environment is shared among AGVs, manually driven vehicles, and human operators. In this situation, safety is a major issue that needs always to be guaranteed, while still maximizing the efficiency of the system. This paper describes some of the main achievements of the PAN-Robots European project.
2016
- Optimizing the use of power in wave based bilateral teleoperation
[Relazione in Atti di Convegno]
Ferraguti, Federica; Fantuzzi, Cesare; Secchi, Cristian
abstract
Because of their simplicity, wave variables have become almost a standard strategy for stabilizing delayed bilateral teleoperation systems. However, the price to pay for a stable behavior is a degradation in the performance of the teleoperation system. Recently, more flexible and transparency oriented bilateral architectures have been proposed (e.g. TDPN, PSPM, Two-Layer approach) but they are complex to implement and to tune. In [1], a strategy for blending the high performance of the new control methodologies with the simplicity of wave based bilateral teleoperation has been proposed. Nevertheless, while appealing in terms of simplicity, this method is conservative in terms of the transparency that can be achieved. In this paper, we extend the architecture in [1] in order to optimize the use of the energy and for achieving a coupling that is as close as possible to the desired one while preserving the passivity of the overall system.
2016
- TIREBOT: A novel tire workshop assistant robot
[Relazione in Atti di Convegno]
Levratti, Alessio; De Vuono, Antonio; Fantuzzi, Cesare; Secchi, Cristian
abstract
In this paper a novel tire workshop assistant robot is presented. The robot can load heavy wheels and transport them in any place of the workshop, lifting the operator from the effort of doing it manually. The operator can interact with the robot through gestures, which are captured by a RGB-D camera and translated into commands, or teleoperate it through a control station equipped with a haptic interface, which can also return a force feedback. The robot can also operate autonomously with a mission manager that decides where the robot has to go in order to accomplish a certain task. The paper presents a description of the design process and motivations of every design choice.
2016
- Tool Compensation and Force Password Identification on Admittance-Controlled Robots in Walk-Through Programming
[Relazione in Atti di Convegno]
TALIGNANI LANDI, Chiara; Ferraguti, Federica; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper presents an example of a walk-through
programming technique that exploits the payload compensation
to execute the teaching phase of the robot programming.
During this phase the human operator grabs the tool attached
to the end-effector and physically walks the robot through
the desired positions without any effort, since the static and
dynamics effects produced by the tool are compensated. In
the meantime, the robot controller records all the poses and
then it will be able to reproduce the trajectory back. The
addition of a “force password” identification allows to start
and stop the recording in a simple way, disregarding the use of
additional external buttons or software commands. Experiments
are used to validate the proposed control architecture and a pick
and place example is presented, to show a realistic industrial
application.
2016
- Tool Compensation in Walk-Through Programming for Admittance-Controlled Robots
[Relazione in Atti di Convegno]
TALIGNANI LANDI, Chiara; Ferraguti, Federica; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper describes a walk-through programming technique, based on admittance control and tool dynamics compensation, to ease and simplify the process of trajectory learning in common industrial setups. In the walk-through programming, the human operator grabs the tool attached at the robot end-effector and "walks" the robot through the desired positions. During the teaching phase, the robot records the positions and then it will be able to interpolate them to reproduce the trajectory back. In the proposed control architecture, the admittance control allows to provide a compliant behavior during the interaction between the human operator and the robot end-effector, while the algorithm of compensation of the tool dynamics allows to directly use the real tool in the teaching phase. In this way, the setup used for the teaching can directly be the one used for performing the reproduction task. Experiments have been performed to validate the proposed control architecture and a pick and place example has been implemented to show a possible application in the industrial field.
2015
- A Quadratic Programming approach for coordinating multi-AGV systems
[Relazione in Atti di Convegno]
Digani, Valerio; Hsieh, M. Ani; Sabattini, Lorenzo; Secchi, Cristian
abstract
This paper presents an optimization strategy to coordinate multiple Autonomous Guided Vehicles (AGVs) on ad-hoc pre-defined roadmaps used in logistic operations in industrial applications. Specifically, the objective is to maximize traffic throughput of AGVs navigating in an automated warehouse by minimizing the time AGVs spend negotiating complex traffic patterns to avoid collisions with other AGVs. In this work, the coordination problem is posed as a Quadratic Programming (QP) problem where the optimization is performed in a centralized manner. The optimality of the coordination strategy is established and the feasibility of the strategy is validated in simulation for different scenarios and for real industrial environments. The performance of the proposed strategy is then compared with a decentralized coordination strategy which relies on local negotiations for shared resources. The results show that the proposed coordination strategy successfully maximizes vehicle throughout and significantly minimizes the time vehicles spend negotiating traffic under different scenarios.
2015
- A dynamic routing strategy for the traffic control of AGVs in automatic warehouses
[Relazione in Atti di Convegno]
Secchi, Cristian; Olmi, Roberto; Rocchi, Fabio; Fantuzzi, Cesare
abstract
In this paper we propose a novel algorithm for the dynamic routing of a group of Autonomous Guided Vehicles (AGVs) used for transporting goods in automatic warehouses. Our strategy allows to improve the efficiency of a fleet of AGVs in terms of delivery time and its computational burden is sufficiently small to be embedded in standard industrial traffic management system. The algorithm is validated in a small-scale automatic warehouse with real AGVs.
2015
- A two-layer approach for shared control in semi-autonomous robotic surgery
[Relazione in Atti di Convegno]
Ferraguti, Federica; Preda, Nicola; De Rossi, Giacomo; Bonfe, Marcello; Muradore, Riccardo; Fiorini, Paolo; Secchi, Cristian
abstract
In autonomous robotic surgery, the supervision of the surgeon cannot be avoided due to the unforeseenable emergencies and complications that can take place during an operation. When necessary, the surgeon has to take over the surgical system switching it from an autonomous mode to a teleoperation mode. In this paper we propose a two-layer bilateral control architecture that ensures a safe behavior during the switch and high performance during the teleoperation. Experiments are proposed for validating the architecture proposed in the paper.
2015
- Advanced sensing and control techniques for multi AGV systems in shared industrial environments
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Cardarelli, Elena; Digani, Valerio; Secchi, Cristian; Fantuzzi, Cesare; Fuerstenberg, Kay
abstract
This paper describes innovative sensing technologies and control techniques, that aim at improving the performance of groups of Automated Guided Vehicles (AGVs) used for logistics operations in industrial environments. We explicitly consider the situation where the environment is shared among AGVs, manually driven vehicles, and human operators. In this situation, safety is a major issue, that needs always to be guaranteed, while still maximizing the efficiency of the system. This paper describes some of the main achievements of the PAN-Robots European project.
2015
- An Energy Tank-Based Interactive Control Architecture for Autonomous and Teleoperated Robotic Surgery
[Articolo su rivista]
Ferraguti, Federica; Preda, Nicola; Manurung, Auralius; Bonfe, Marcello; Lambercy, Olivier; Gassert, Roger; Muradore, Riccardo; Fiorini, Paolo; Secchi, Cristian
abstract
Introducing some form of autonomy in robotic surgery is being considered by the medical community to better exploit the potential of robots in the operating room. However, significant technological steps have to occur before even the smallest autonomous task is ready to be presented to the regulatory authorities. In this paper, we address the initial steps of this process, in particular the development of control concepts satisfying the basic safety requirements of robotic surgery, i.e., providing the robot with the necessary dexterity and a stable and smooth behavior of the surgical tool. Two specific situations are considered: the automatic adaptation to changing tissue stiffness and the transition from autonomous to teleoperated mode. These situations replicate real-life cases when the surgeon adapts the stiffness of her/his arm to penetrate tissues of different consistency and when, due to an unexpected event, the surgeon has to take over the control of the surgical robot. To address the first case, we propose a passivity-based interactive control architecture that allows us to implement stable time-varying interactive behaviors. For the second case, we present a two-layered bilateral control architecture that ensures a stable behavior during the transition between autonomy and teleoperation and, after the switch, limits the effect of initial mismatch between master and slave poses. The proposed solutions are validated in the realistic surgical scenario developed within the EU-funded I-SUR project, using a surgical robot prototype specifically designed for the autonomous execution of surgical tasks like the insertion of needles into the human body.
2015
- Autonomous Execution of Surgical Tasks: the Next Step in Robotic Surgery
[Relazione in Atti di Convegno]
Muradore, Riccardo; De Rossi, Giacomo; Bonfé, Marcello; Preda, Nicola; Secchi, Cristian; Ferraguti, Federica; Fiorini, Paolo
abstract
Minimally invasive surgery first and, more recently, surgical robotics have brought new perspectives to surgery and have significantly improved the quality of many critical surgical tasks [1,2].
In this paper we go further by describing the design and testing of an architecture to control a robotic platform capable of executing in an autonomous way basic surgical tasks such as US-guided needle insertion and suturing. The results have been obtained during the FP7 European funded project Intelligent Surgical Robotics (I-SUR, grant agreement n. 270396). The main goal of the project was to demonstrate that autonomous surgical robotics can carry out simple surgical tasks effectively and without major intervention by surgeons. To fulfil this goal, we have developed an innovative approach (both in terms of technologies and algorithms) for planning and execution of movement of robot arms in contact with the deformable anatomical environment.
2015
- Bilateral teleoperation of a dual arms surgical robot with passive virtual fixtures generation
[Relazione in Atti di Convegno]
Ferraguti, Federica; Preda, Nicola; Bonfe, Marcello; Secchi, Cristian
abstract
The paper describes a passivity based approach to the generation of virtual fixtures for robotic teleoperation schemes involving multiple masters and multiple slaves. Virtual fixtures considered in the paper aim to guide the user towards a geometric path, which is assumed to be collision-free by design, describing a desired execution of a given task. To preserve safe distance from obstacles and at the same time suggest the user a preferred direction to progress along the path, the virtual fixtures are generated by arbitrarily redirecting assistive forces obtained by summation of attractive and repulsive potential fields. The main result of the paper is the definition of a passivity preserving condition for this redirection, so that the behavior of the teleoperated systems remains safe and stable. The proposed assisted mode of teleoperation has been tested on a surgical robot prototype with dual arms configuration, since robotic surgery represents a suitable application domain for such control schemes.
2015
- Cloud robotics paradigm for enhanced navigation of autonomous vehicles in real world industrial applications
[Relazione in Atti di Convegno]
Cardarelli, Elena; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
Autonomous vehicles require advances sensing technologies, in order to be able to safely share the environment with human operators. Those sensing technologies are in fact necessary for identifying the presence of unforeseen objects, and measuring their position and velocity. Furthermore, classification is necessary for effectively predicting their behavior. In this paper we consider the presence of sensing systems both on-board each vehicle, and installed on infrastructural elements. While the simultaneous presence of multiple sources of information heavily improves the amount (and quality) of available data, it generates the need for effective data fusion and storage systems. Hence, we introduce a centralized cloud service, that is in charge of receiving and merging data acquired by different sensing systems. Those data are then distributed to the autonomous vehicles, that exploit them for implementing advanced navigation strategies. The proposed methodology is validated in a real industrial environment to safely perform obstacle avoidance with an autonomously driven forklift.
2015
- Conducting multi-robot systems: Gestures for the passive teleoperation of multiple slaves
[Relazione in Atti di Convegno]
Secchi, Cristian; Sabattini, Lorenzo; Fantuzzi, Cesare
abstract
When teleoperating a multi-robot system it is useful to control the kind of behavior of the fleet depending on the environment it is moving in. In this paper, a novel bilateral control architecture for teleoperating a group of mobile robots is proposed. The user can command the robots both as a flexible and amorphous group and as a set of agents executing different trajectories for achieving a desired task, mimicking a conductor-orchestra paradigm. Exploiting passivity based control, we ensure a stable and safe behavior for the user. The proposed teleoperation strategy is validated by means of experiments.
2015
- Coordinated dynamic behaviors in multi-robot systems with time-varying topologies
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Levratti, Alessio; Cocetti, Matteo; Fantuzzi, Cesare
abstract
A control strategy for the execution of coordinated complex dynamic behaviors in multi-robot systems is introduced in this paper. In particular, considering a dependent-independent robot partitioning of a multi-robot system, we introduce a methodology for controlling the independent robots in such a way that, exploiting local interaction, the dependent robots are driven to track desired periodic setpoint trajectories. The control strategy is designed taking explicitly into account variations in the interconnection topology, due to relative movements among the robots.
2015
- Decentralized Connectivity Maintenance for Networked Lagrangian Dynamical Systems with Collision Avoidance
[Articolo su rivista]
Sabattini, Lorenzo; Secchi, Cristian; Chopra, Nikhil
abstract
In order to accomplish cooperative tasks, multi–robot systems are required to communicate among each other. Thus, maintaining the connectivity of the communication graph is a fundamental issue. Connectivity maintenance has been extensively studied in the last few years, but generally considering only kinematic agents. In this paper we will introduce a control strategy that, exploiting a decentralized procedure for the estimation of the algebraic connectivity of the graph, ensures the connectivity maintenance for groups of Lagrangian systems. Collision avoidance control actions are also integrated with the connectivity maintenance. The control strategy is validated by means of analytical proofs and simulation results.
2015
- Decentralized Control of Cooperative Robotic Systems for Arbitrary Setpoint Tracking while Avoiding Collisions
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Levratti, Alessio; Fantuzzi, Cesare
abstract
Decentralized control strategies for multi-robot systems have been extensively studied in the literature, with the aim of regulating the overall state of the system to some desired configuration. Recently a few works have appeared that propose methodologies for solving more complex problems: in particular, partitioning of the multi-robot system into two subgroups can be exploited for cooperatively tracking arbitrarily defined setpoint functions. Specifically, a small number of independent robots can be exploited for controlling the overall state of the dependent robots. Based on this formulation, in this paper we exploit the null space based behavioral approach to obtain setpoint tracking for a multi-robot system, while avoiding inter-robot collisions.
2015
- Decentralized Estimation and Control for Preserving the Strong Connectivity of Directed Graphs
[Articolo su rivista]
Sabattini, Lorenzo; Secchi, Cristian; Chopra, Nikhil
abstract
In order to accomplish cooperative tasks, decentralized systems are required to communicate among each other. Thus, maintaining the connectivity of the communication graph is a fundamental issue. Connectivity maintenance has been extensively studied in the last few years, but generally considering undirected communication graphs. In this paper, we introduce a decentralized control and estimation strategy to maintain the strong connectivity property of directed communication graphs. In particular, we introduce a hierarchical estimation procedure that implements power iteration in a decentralized manner, exploiting an algorithm for balancing strongly connected directed graphs. The output of the estimation system is then utilized for guaranteeing preservation of the strong connectivity property. The control strategy is validated by means of analytical proofs and simulation results.
2015
- Decentralized state estimation for heterogeneous multi-agent systems
[Relazione in Atti di Convegno]
Boem, Francesca; Sabattini, Lorenzo; Secchi, Cristian
abstract
The paper proposes a decentralized state estimation method for the control of multi-agent networked systems, where the goal is the tracking of arbitrary setpoint functions. The cooperative agents are partitioned into independent robots, providing the control inputs, and dependent robots, controlled by local interaction laws. The proposed state estimation algorithm allows the independent robots to estimate the state of the dependent robots in a completely decentralized way. To do that, it is necessary for each independent robot to estimate the control input components computed by the other independent robots, without requiring communication among the independent robots. The decentralized state estimator, including an input estimator, is developed and the convergence properties are studied. Simulation results show the effectiveness of the proposed approach.
2015
- Design, identification and experimental testing of a light-weight flexible-joint arm for aerial physical interaction
[Relazione in Atti di Convegno]
Yuksel, Burak; Mahboubi, Saber; Secchi, Cristian; Bulthoff, Heinrich H.; Franchi, Antonio
abstract
In this paper we introduce the design of a light-weight novel flexible-joint arm for light-weight unmanned aerial vehicles (UAVs), which can be used both for safe physical interaction with the environment and it represents also a preliminary step in the direction of performing quick motions for tasks such as hammering or throwing. The actuator consists of an active pulley driven by a rotational servo motor, a passive pulley which is attached to a rigid link, and the elastic connections (springs) between these two pulleys. We identify the physical parameters of the system, and use an optimal control strategy to maximize its velocity by taking advantage of elastic components. The prototype can be extended to a light-weight variable stiffness actuator. The flexible-joint arm is applied on a quadrotor, to be used in aerial physical interaction tasks, which implies that the elastic components can also be used for stable interaction absorbing the interactive disturbances which might damage the flying system and its hardware. The design is validated through several experiments, and future developments are discussed in the paper.
2015
- Development of a cognitive robotic system for simple surgical tasks
[Articolo su rivista]
Muradore, Riccardo; Fiorini, Paolo; Akgun, Gokhan; Barkana, Duygun Erol; Bonfe, Marcello; Borierol, Fabrizio; Caprara, Andrea; De Rossi, Giacomo; Dodi, Riccardo; Elle, Ole Jakob; Ferraguti, Federica; Gasperottil, Lorenza; Gassert, Roger; Mathiassen, Kim; Handini, Dilla; Lambercy, Olivier; Lil, Lin; Kruusmaal, Maarja; Manurung, Auralius Oberman; Meruzzi, Giovanni; Ho Quoc Phuong, Nguyen; Freda, Nicola; Riolfo, Gianluca; Ristolainen, Asko; Sanna, Alberto; Secchi, Cristian; Torsello, Marco; Yantacil, Asim Evren
abstract
The introduction of robotic surgery within the operating rooms has significantly improved the quality of many surgical procedures. Recently, the research on medical robotic systems focused on increasing the level of autonomy in order to give them the possibility to carry out simple surgical actions autonomously. This paper reports on the development of technologies for introducing automation within the surgical workflow. The results have been obtained during the ongoing FP7 European funded project Intelligent Surgical Robotics (I-SUR). The main goal of the project is to demonstrate that autonomous robotic surgical systems can carry out simple surgical tasks effectively and without major intervention by surgeons. To fulfil this goal, we have developed innovative solutions (both in terms of technologies and algorithms) for the following aspects: fabrication of soft organ models starting from CT images, surgical planning and execution of movement of robot arms in contact with a deformable environment, designing a surgical interface minimizing the cognitive load of the surgeon supervising the actions, intra-operative sensing and reasoning to detect normal transitions and unexpected events. All these technologies have been integrated using a component-based software architecture to control a novel robot designed to perform the surgical actions under study. In this work we provide an overview of our system and report on preliminary results of the automatic execution of needle insertion for the cryoablation of kidney tumours.
2015
- Edge-Weighted Consensus Based Formation Control Strategy With Collision Avoidance
[Articolo su rivista]
Falconi, R.; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare; Melchiorri, C.
abstract
In this paper, a consensus-based control strategy is presented to gather formation for a group of differential-wheeled robots. The for- mation shape and the avoidance of collisions between robots are ob- tained by exploiting the properties of weighted graphs. Since mobile robots are supposed to move in unknown environments, the presented approach to multi-robot coordination has been extended in order to include obstacle avoidance. The effectiveness of the proposed control strategy has been demonstrated by means of analytical proofs. More- over, results of simulations and experiments on real robots are provided for validation purposes.
2015
- Eigenvalue placement for asymptotic stability in piecewise linear switched systems
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we provide an eigenvalue placement methodology that guarantees asymptotic stability in a piecewise linear switched system where a lowerbound on the dwell time is known in advance. In particular, considering the case where each subsystem is a linear controllable system, we introduce an algorithm for placing the eigenvalues of each subsystem in such a way that the overall switched system is asymptotically stable. This is obtained defining a relationship between the dwell time and the stability properties of each subsystem. Simulations of a heterogeneous multi-robot system are provided for validation purposes.
2015
- Ensemble Coordination Approach in Multi-AGV Systems Applied to Industrial Warehouses
[Articolo su rivista]
Digani, Valerio; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper deals with a holistic approach to coordinate a fleet of automated guided vehicles (AGVs) in an industrial environment. We propose an ensemble approach based on a two layer control architecture and on an automatic algorithm for the definition of the roadmap. The roadmap is built by considering the path planning algorithm implemented on the hierarchical architecture and vice versa. In this way, we want to manage the coordination of the whole system in order to increase the flexibility and the global efficiency. Furthermore, the roadmap is computed in order to maximize the redundancy, the coverage and the connectivity. The architecture is composed of two layers. The low-level represents the roadmap itself. The high-level describes the topological relationship among different areas of the environment. The path planning algorithm works on both these levels and the subsequent coordination among AGVs is obtained exploiting shared resource (i.e., centralized information) and local negotiation (i.e., decentralized coordination). The proposed approach is validated by means of simulations and comparison using real plants.
2015
- Implementation of Coordinated Complex Dynamic Behaviors in Multirobot Systems
[Articolo su rivista]
Sabattini, Lorenzo; Secchi, Cristian; Cocetti, Matteo; Levratti, Alessio; Fantuzzi, Cesare
abstract
Decentralized control strategies for multirobot systems have been extensively studied over the past few years. Typically, these strategies aim at exploiting local interaction rules to regulate the overall state of the multirobot system toward a desired configuration, thus generating some desired coordinated behaviors, such as synchronization, swarming, deployment, or formation control. However, when considering the real-world application of multirobot systems, more complex cooperative dynamic behaviors are desirable. Along these lines, in this paper, we propose a methodology to control a multirobot system for cooperatively tracking arbitrarily defined periodic setpoint trajectories. This objective is fulfilled partitioning the multirobot system into independent robots (that can provide control inputs) and dependent robots (that are controlled through local interaction). The motion of the independent robots is then defined in such a way that, exploiting local interactions, the dependent robots are controlled to track the desired trajectories. The proposed control strategy is validated by means of simulations and experiments on real robots.
2015
- Improving AGV systems: Integration of advanced sensing and control technologies
[Relazione in Atti di Convegno]
Oleari, Fabio; Magnani, Massimiliano; Ronzoni, Davide; Sabattini, Lorenzo; Cardarelli, Elena; Digani, Valerio; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper focuses on the integration of advanced sensing and control technologies into advanced systems of multiple Automated Guided Vehicles (AGVs). In particular, we focus on the key technologies developed within the Plug-and-Navigate Robots (PAN-Robots) project, highlighting how those results contribute to improving the performance of AGV systems.
2015
- Improving robustness in multi-robot networks
[Relazione in Atti di Convegno]
Ghedini, Cinara; Secchi, Cristian; Ribeiro, Carlos H. C.; Sabattini, Lorenzo
abstract
This paper addresses the topological robustness of robot networks under failures; a subject often neglected in the literature. Robots are likely to fail due to several causes, which may lead to a poorly connected or a fragmented network. Our purpose is to discuss how to design resilient robot networks. For that, we first demonstrate the problem analyzing the results from a protocol to simulate failures of both central and random (w.r.t. topology) robots. Then, we propose mechanisms for detecting the probability of a robot being in a fragile local configuration and for improving its local robustness. The procedures rely solely on local information: each robot estimates its probability of being in a harmful configuration based on the positions of its neighbors. Such probability is estimated as the number of paths connecting a robot to its 2-hop neighbors by the number of paths existing in the subgraph encompassing its 1-hop and 2-hop neighborhoods. For reversing an adverse configuration, robots change their position to an average position towards their 2-hop neighbors with fewer alternative paths. The results showed that the proposed mechanism is efficient for detecting fragile topological configurations and for improving the overall network robustness.
2015
- Interacting with a multi AGV system
[Relazione in Atti di Convegno]
Cardarelli, Elena; Sabattini, Lorenzo; Digani, Valerio; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper introduces a novel Human Machine Interface (HMI) that allows users to interact with a fleet of Automated Guided Vehicles (AGVs) used for logistics operations in industrial environments. The interface is developed for providing operators with information regarding the fleet of AGVs, and the status of the industrial environment. Information is provided in an intuitive manner, utilizing a three-dimensional representation of the elements in the environment. The HMI also allows operators to influence the behavior of the fleet of AGVs, manually inserting missions to be accomplished.
2015
- Mission Assignment for Multi-Vehicle Systems in Industrial Environments
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Digani, Valerio; Lucchi, Matteo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we introduce a methodology for mission assignment in multiple vehicle system exploited in industrial environments for logistics operations. We explicitly consider the model of the traffic, for performing an optimized dynamic mission assignment. Simulation results are provided for comparing the proposed methodology with state-of-the-art techniques, that do not consider the state of the traffic while allocating missions.
2015
- Port-Hamiltonian based teleoperation of a multi-robot system on periodic trajectories
[Relazione in Atti di Convegno]
Secchi, Cristian; Sabattini, Lorenzo; Fantuzzi, Cesare
abstract
In this paper, we exploit port-Hamiltonian systems for building a novel teleoperation
architecture for a group of mobile agents that need to track a set of prede_ned trajectories.
Using port-Hamiltonian system we can guarantee an intrinsically safe and passive bilateral
teleoperation system while using linear regulation system we can ensure an asymptotic
tracking. The performance of the teleoperation system are evaluated by means of
experiments.
2014
- A nonlinear force observer for quadrotors and application to physical interactive tasks
[Relazione in Atti di Convegno]
Yuksel, Burak; Secchi, Cristian; Bulthoff, Heinrich H.; Franchi, Antonio
abstract
In order to properly control the physical inter- active behavior of a flying vehicle, the information about the forces acting on the robot is very useful. Force/torque sensors can be exploited for measuring such information but their use increases the cost of the equipment, the weight to be carried by the robot and, consequently, it reduces the flying autonomy. Furthermore, a sensor can measure only the force/torque applied to the point it is mounted in. In order to overcome these limitations, in this paper we introduce a Lyapunov based nonlinear observer for estimating the external forces applied to a quadrotor. Furthermore, we show how to exploit the estimated force for shaping the interactive behavior of the quadrotor using Interconnection and Damping Assignment Passivity Based Controller (IDA-PBC). The results of the paper are validated by means of simulations.
2014
- An automatic approach for the generation of the roadmap for multi-AGV systems in an industrial environment
[Relazione in Atti di Convegno]
Digani, Valerio; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper deals with the automatic generation of a
roadmap. We propose an approach to build a roadmap
for Automated Guided Vehicles (AGVs) used for
logistics operations in industrial environments. The
algorithm computes a roadmap in such a way that the
coverage, the connectivity and the redundancy of the
paths are maximized. In this way the flexibility and
the efficiency of the AGV system can be
increased. The proposed approach is validated by
means of comparison with different roadmaps manually
built in real plants
2014
- Controllability and Observability Preservation for Networked Systems with Time Varying Topologies
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Fantuzzi, Cesare; Secchi, Cristian
abstract
When dealing with networked systems, the concept of
controllability refers to the possibility of
controlling the overall state of a group of agents
by providing an external input only to a subset of
them, that are referred to as leaders. On the same
lines, the concept of observability is related to
the possibility of observing the whole state of the
networked system from only a subset of the
agents. In this paper we introduce a decentralized
interaction rule that ensures preservation of the
controllability and observability properties of a
networked system. The proposed strategy is based on
the fact that these properties are strongly related
to the topology of the underlying communication
graph. We will show that connectivity maintenance
and a random choice of the edge-weights are key
concepts to ensure controllability and observability
preservation for a networked system
2014
- Cooperative dynamic behaviors in networked systems with decentralized state estimation
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
Networked systems and decentralized control strategies
have been widely investigated in the literature,
with the objective of obtaining coordinated emerging
behaviors by means of local interaction. While
typical approaches aim at solving regulation
problems (e.g. synchronization, swarming, coverage,
formation control) a few works have recently
appeared that move towards the solution of more
complex problems, such as tracking of arbitrary
setpoint functions. Based on the formulation
introduced in [1], this objective is obtained in
this paper partitioning the networked systems into
leaders (that can provide control inputs) and
followers (that are controlled through local
interaction). In this paper we provide a methodology
for letting the leaders estimate the state of the
followers in a decentralized manner: this estimate
is then used for control purposes. Simulations are
provided for validating the proposed control
strategy
2014
- Distributed Control Architecture for Automated Surgical Task Execution with Coordinated Robot Arms
[Relazione in Atti di Convegno]
Bonfé, M.; Preda, N.; Secchi, Cristian; Ferraguti, Federica; Muradore, R.; Repele, L.; Lorenzi, G.; Fiorini, P.
abstract
The paper describes a robot control and coordination framework for the automation of surgical tasks. In the proposed framework, surgeons are supported by autonomous robotic assistants and do not teleoperate robots, unless in case of exceptions in the tasks of the robots. Such robots perform basic surgical actions by combining sensing, dexterity and cognitive capabilities. The goal is achieved thanks to rigorous assessment of surgical requirements, formal specification of robotic system behavior, including multiple arm coordination and human/system interaction, and control software development with state-of-the-art component- based technologies. The paper presents an experimental setup composed of two robots operating on a US-compatible phantom, demonstrating the feasibility of the approach.
2014
- Hierarchical traffic control for partially decentralized coordination of multi AGV systems in industrial environments
[Relazione in Atti di Convegno]
Digani, Valerio; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper deals with decentralized coordination of
Automated Guided Vehicles (AGVs). We propose a
hierarchical traffic control algorithm, that
implements path planning on a two layer
architecture. The high-level layer describes the
topological relationships among different areas of
the environment. In the low-level layer, each area
includes a set of fixed routes, along which the AGVs
have to move. An algorithm is also introduced for
the automatic definition of the route map
itself. The coordination among the AGVs is obtained
exploiting shared resources (i.e. centralized
information) and local negotiation
(i.e. decentralized coordination). The proposed
strategy is validated by means of simulations using
real plant
2014
- Implementation of arbitrary periodic dynamic behaviors in networked systems
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Cocetti, Matteo; Fantuzzi, Cesare
abstract
Decentralized control of networked systems has been
widely investigated in the literature, with the aim
of regulating the overall state of the system to
some desired configuration, thus obtaining
coordinated emerging behaviors
(e.g. synchronization, swarming, coverage, formation
control) by means of local interaction. In this
paper we introduce a methodology to solve a tracking
problem, that is defining a decentralized control
strategy for making a networked system follow an
arbitrarily defined periodic setpoint function. The
most suitable interconnection topology is defined
together with the control law as the solution of a
constrained optimization problem, in order to ensure
asymptotic tracking. Simulations are provided for
validating the proposed control strategy
2014
- Multisensor data fusion for obstacle detection in automated factory logistics
[Relazione in Atti di Convegno]
Cardarelli, Elena; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper describes data fusion methodologies for obstacle
detection in an automation system based on advanced
Automatic Guided Vehicles (AGV), used for automated
logistics in modern factories. We present the
background of the problem, introducing generic
aspects of the system architecture designed to cope
with the obstacle detection in automated factory
logistics; then, we focus on the system
specification for the module responsible of
integrating data from different sources and
providing a global representation of the
environment. Finally, we present a comparative
analysis among different strategies of multisensor
data fusion compliant with the requirements of the
described system, highlighting their advantages and
drawbacks
2014
- Obstacle avoidance for industrial AGVs
[Relazione in Atti di Convegno]
Digani, Valerio; Caramaschi, Fabrizio; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
IEEE International Conference
2014
- Planning and Simulation of Percutaneous Cryoablation
[Relazione in Atti di Convegno]
Dodi, Riccardo; Ferraguti, Federica; Ristolainen, Asko; Secchi, Cristian; Sanna, Alberto
abstract
New technological methods to assist percutaneous cryoablation procedures are here presented, namely a planning software and a simulation algorithm. The first has the role to calculate a feasible displacement of the tools to ensure an effective ablation of the lesion, satisfying well-specified procedural constraints. Starting from intra-operative CT scans of the patient, a virtual model of the anatomical site is obtained and uploaded. The displacement of the cryoprobes is computed in order to cover the whole volume of the tumour with the developed iceball, but minimizing the damage to surrounding healthy renal tissue. On the other hand, the simulation algorithm is a graphical tool useful to assess the temperature distribution throughout the evolution of the procedure. A discrete iterative function calculates the heat transfer from the probes to the surrounding tissue within a specified three-dimensional grid: the isolation of significant isotherms can help to assess whether the whole tumour will be frozen or not. By using a real intra-operative dataset of a successful percutaneous cryoablation, the volume of the real iceball has been matched with that generated from the simulator, showing a good accuracy in terms of dimension and shape. Even though been designed to be integrated within a robotic system, this method is usable and extensible for different purposes and adapted to simulate other scenarios or procedures.
2014
- Reshaping the physical properties of a quadrotor through IDA-PBC and its application to aerial physical interaction
[Relazione in Atti di Convegno]
Yuksel, Burak; Secchi, Cristian; Bulthoff, Heinrich H.; Franchi, Antonio
abstract
In this paper we propose a controller, based on an extension of
Interconnection and Damping Assignment-Passivity Based Control
(IDA-PBC) framework, for shaping the whole physical characteristics of
a quadrotor and for obtaining a
desired interactive behavior between the robot and the environment. In
the control design, we shape the total energy (kinetic and potential)
of the undamped original system by first excluding external effects. In
this way we can assign a new dynamics to the system. Then we apply
damping injection to the new system for achieving a desired damped
behavior. Then we show how to connect a high-level control input to
such system by taking advantage of the new desired physics. We support
the theory with extensive simulations by changing the overall behavior
of the UAV for different desired dynamics, and show the advantage of
this method for sliding on a surface tasks, such as ceiling painting, cleaning or surface inspection.
2014
- TRAFCON – Traffic Control of AGVs in Automatic Warehouses
[Capitolo/Saggio]
Secchi, Cristian; Olmi, R.; Fantuzzi, Cesare; Casarini,
abstract
In this chapter we illustrated the main results of the TRAF- CON experiment. We propose a novel traffic manager for AGVs moving in an automatic warehouse and its experimental validation on simulated real plants and on a small-scale automatic warehouse.
2013
- A Component-Based Software Architecture for Control and Simulation of Robotic Manipulators
[Relazione in Atti di Convegno]
Ferraguti, Federica; Golinelli, Nicola; Secchi, Cristian; N., Preda; M., Bonfé
abstract
The paper describes a software architecture for control and simulation of a generic robotic manipulator. The algorithmic part of the system is implemented using the Orocos component-based framework and its related library for robotic applications, while the graphical animation of the robot is developed with Blender. The proposed control and simulation framework is modular, reconfigurable and computationally efficient. Moreover, it can be seamlessly integrated into a more complex control architecture for a complete intelligent robotic system.
2013
- A Passivity-Based Decentralized Strategy for Generalized Connectivity Maintenance
[Articolo su rivista]
P., Robuffo Giordano; A., Franchi; Secchi, Cristian; H. H., Buelthoff
abstract
The design of decentralized controllers coping with the typical constraints on the inter-robot sensing/communication capabilities represents a promising direction in multi-robot re- search thanks to the inherent scalability and fault tolerance of these approaches. In these cases, connectivity of the underlying interaction graph plays a fundamental role: it represents a necessary condition for allowing a group or robots achieving a common task by resorting to only local information. Goal of this paper is to present a novel decentralized strategy able to enforce connectivity maintenance for a group of robots in a flexible way, that is, by granting large freedom to the group internal configuration so as to allow establishment/deletion of interaction links at anytime as long as global connectivity is preserved. A peculiar feature of our approach is that we are able to embed into a unique connectivity preserving action a large number of constraints and requirements for the group: (i) presence of specific inter-robot sensing/communication models, (ii) group requirements such as formation control, and (iii) individual requirements such as collision avoidance. This is achieved by defining a suitable global potential function of the second smallest eigenvalue λ2 of the graph Laplacian, and by computing, in a decentralized way, a gradient-like controller built on top of this potential. Simulation results obtained with a group of quadorotor UAVs and UGVs, and experimental results obtained with four quadrotor UAVs, are finally presented to thoroughly illustrate the features of our approach on a concrete case study.
2013
- A Tank-Based Approach to Impedance Control with Variable Stiffness
[Relazione in Atti di Convegno]
Ferraguti, Federica; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper, we present a new impedance control strategy that allows to reproduce a time-varying stiffness. By properly controlling the energy exchanged during the action, we guarantee the system passivity for any choice of the stiffness matrix, especially in case of time-varying stiffness, and therefore a stable behavior of the robot both in free motion and in interaction with an environment.
A possible application of the presented algorithm is the reproduction of surgeon’s behavior during a puncturing task. In this application, the stiffness is changed depending on the layer of the human body the needle is crossing.
To demonstrate the validity of the proposed method we conducted several simulations. Then, in order to prove the effec- tive useless of the proposed strategy, we built an experimental setup reproducing the puncturing scenario and implemented the algorithm by means of a 7 degree of freedom (DOF) robot manipulator.
2013
- A low cost localization algorithm for an autonomous lawnmower
[Relazione in Atti di Convegno]
Levratti, Alessio; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper aims at implementing a localization algorithm, based on a Kalman filter, in order to localize an autonomous lawnmower which operates in an outdoor environment using only low cost sensors. In particular the position and the orientation of the robot are estimated using an IMU (Inertial Measurement Unit), an RFID (Radio Frequency IDentification) antenna and an RFID reader (which reads the presence of RFID tags scattered on the border of the lawn to be mowed) and a Wifi antenna, on-board the robot, which measures the RSSI (Received Signal Strength Indicator) of the signal sent by other Wifi end devices positioned in the working area in known positions. The efficiency of the proposed algorithm is then tested first through simulations and then experimentally on a prototype lawnmower.
2013
- An Algorithm for Planning the Number and the Pose of the Iceballs in Cryoablation
[Relazione in Atti di Convegno]
M., Torricelli; Ferraguti, Federica; Secchi, Cristian
abstract
We present an algorithm that computes the number and the pose (position and orientation) of iceballs in a cryoablation procedure, in order to completely cover the target region, i.e. the tumor. Constraints to needle insertion, such as regions that have to be avoided, are taken into account and satisfied. We developed a tool for cryosurgery planning in MATLAB and perform several simulations to extract information on the algorithm behavior and to verify that it always brings to a complete coverage.
2013
- Automated Surgical Task Execution: the Next Step in Robotic Surgery
[Relazione in Atti di Convegno]
Bonfé, M.; Preda, N.; Secchi, Cristian; Ferraguti, Federica; Muradore, R.; Repele, L.; Lorenzi, G.; Gasperotti, L.; Fiorini, P.
abstract
****
2013
- Bilateral Control of the Degree of Connectivity in Multiple Mobile-robot Teleoperation
[Relazione in Atti di Convegno]
Secchi, Cristian; A., Franchi; H. H., Buelthoff; P., Robuffo Giordano
abstract
This paper presents a novel bilateral controller that allows to stably teleoperate the degree of connectivity in the mutual interaction between a remote group of mo- bile robots considered as the slave-side. A distributed leader- follower scheme allows the human operator to command the overall group motion. The group autonomously maintains the connectivity of the interaction graph by using a decentralized gradient descent approach applied to the Fiedler eigenvalue of a properly weighted Laplacian matrix. The degree of connectivity, and then the flexibility, of the interaction graph can be finely tuned by the human operator through an additional bilateral teleoperation channel. Passivity of the overall system is theoretically proven and extensive human/hardware in-the-loop simulations are presented to empirically validate the theoretical analysis.
2013
- Closed-Curve Trajectory Tracking for Decentralized Systems of Multiple Mobile Robots
[Articolo su rivista]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we address the problem of making a group of mobile robots cooperatively track an assigned path. We consider paths described by com- pletely arbitrarily shaped closed curves. The proposed control strategy is a fully decentralized algorithm and it does not require any global synchronization. The desired behavior is obtained by means of some properly designed artificial poten- tial functions. Analytical proofs are provided to show the asymptotic convergence of the system to the desired behavior. Matlab simulations and experiments on real robots are described as well for validation purposes.
2013
- Collision Avoidance Using Gyroscopic Forces for Cooperative Lagrangian Dynamical Systems
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we introduce a collision avoidance control strategy for groups of mobile robots moving in a three-dimensional environment, whose dynamics are described according to the Lagrangian model. The proposed strategy is based on the use of gyroscopic forces, that ensure obstacle avoidance without interfering with the convergence properties of the multi-robot system's desired control law. Moreover, we introduce a method to define the direction of the force in an optimal way, in order to introduce the smallest possible perturbation with respect to the desired behavior of the system. Collision avoidance and convergence properties are analytically demonstrated, and simulation results are provided for validation purpose.
2013
- Decentralized Control Strategy for the Implementation of Cooperative Dynamic Behaviors in Networked Systems
[Relazione in Atti di Convegno]
M., Cocetti; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
Decentralized control of networked systems has been widely investigated in the literature, with the aim of obtaining coordinated emerging behaviors (e.g. synchronization, swarming, coverage, formation control) by means of local interaction. In this paper we consider the possibility of injecting external inputs into the networked system, in order to obtain more complex cooperative behaviors. Specifically, we introduce a strategy that makes it possible to control the overall state of the networked system by directly controlling only a subset of the networked agents, namely the leaders. Exploiting local interaction rules, it is possible to define the inputs for the leaders in such a way that each follower is forced to track a desired periodic setpoint.
2013
- Decentralized Control for Maintenance of Strong Connectivity for Directed Graphs
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; N., Chopra
abstract
In order to accomplish cooperative tasks, decentralized systems are required to communicate among each other. Thus, maintaining the connectivity of the communication graph is a fundamental issue. Connectivity maintenance has been extensively studied in the last few years, but generally considering undirected communication graphs. In this paper we introduce a decentralized control and estimation strategy to maintain the strong connectivity property of directed communication graphs. The control strategy is initially developed for balanced digraphs, and is then extended to generic strongly connected digraphs, introducing a decentralized balancing algorithm. The control strategy is validated by means of analytical proofs and simulation results.
2013
- Decentralized Global Connectivity Maintenance for Interconnected Lagrangian Systems in the Presence of Data Corruption
[Articolo su rivista]
Secchi, Cristian; Sabattini, Lorenzo; Fantuzzi, Cesare
abstract
In order to accomplish cooperative tasks, multi-robot systems are required to communicate among each other. Thus, maintaining the connectivity of the communication graph is a fundamental issue. In this paper we develop a strategy based on Sabattini et al., Decentralized Connectivity Maintenance for Networked Lagrangian Dynamical Systems, 2012 for guaranteeing connectivity in the presence of data corruption. In fact, when dealing with real systems, several sources of data corruption can appear. For instance, sensor noise is one of the primary sources of data corruption. Moreover, when dealing with interconnected robotic systems, assuming instantaneous exchange of data is often unrealistic: com- munication delays are then another important source of data corruption. For this reason, we provide a solution to the connectivity maintenance problem for interconnected Lagrangian dynamical agents, in the presence of data corruption.
2013
- Decentralized connectivity maintenance for cooperative control of mobile robotic systems
[Articolo su rivista]
Sabattini, Lorenzo; Chopra, N.; Secchi, Cristian
abstract
To accomplish cooperative tasks, robotic systems are often required to communicate with each other. Thus, maintaining connectivity of the communication graph is a fundamental issue in the field of multi– robot systems. In this paper we present a completely decentralized control strategy for global connectivity maintenance of the commu- nication graph. We describe a gradient–based control strategy that exploits decentralized estimation of the algebraic connectivity. Unlike previous approaches available in the literature, the proposed control algorithm solves the global connectivity problem in a decentralized manner providing theoretical guarantees, without requiring mainte- nance of the local connectivity between robotic systems. Moreover, results obtained with simulations and experiments on real robots are described for demonstrating the efficacy of the proposed algorithm.
2013
- Design Patterns for Model-Based Automation Software Design and Implementation
[Articolo su rivista]
M., Bonfé; Fantuzzi, Cesare; Secchi, Cristian
abstract
The paper presents the application of object-oriented modeling techniques to control software development for complex manufacturing systems, with particular focus on case studies taken from the packaging industry and designpatterns that can be abstracted from such case studies. The proposed methodology for control software modeling and implementation is based on a practical approach refined on the basis of on-the-field experience and interactions with control engineers involved in the development projects.The final objective of the paper is to review and analyze patterns for the solution of design and implementation issues that typically arise in the considered application domain.
2013
- Distributed Control of Multirobot Systems With Global Connectivity Maintenance
[Articolo su rivista]
Sabattini, Lorenzo; Secchi, Cristian; Chopra, N.; Gasparri, A.
abstract
This work introduces a control algorithm that, exploiting a completely decentralized estimation strategy for the algebraic connectiv- ity of the graph, ensures the connectivity maintenance property for multi– robot systems, in the presence of a generic (bounded) additional control term. This result is obtained driving the robots along the negative gradient of an appropriately defined function of the algebraic connectivity. The proposed strategy is then enhanced, with the introduction of the concept of critical robots, that is robots for which the loss of a single communi- cation link might cause the disconnection of the communication graph. Limiting the control action to critical robots will be shown to reduce the control effort introduced by the proposed connectivity maintenance control law and to mitigate its effect on the additional (desired) control term.
2013
- Erratum: A passivity-based decentralized strategy for generalized connectivity maintenance (International Journal of Robotics Research (2013) 32:3 (299-323) DOI:10.1177/0278364912469671)
[Articolo su rivista]
Giordano, P. R.; Franchi, A.; Secchi, C.; Bulthoff, H. H.
abstract
Paolo Robuffo Giordano, Antonio Franchi, Cristian Secchi and Heinrich H Bulthoff A Passivity-Based Decentralized Strategy for Generalized Connectivity Maintenance The International Journal of Robotics Research, Vol. 32(3): pp. 299-323 (2013) DOI: 10.1177/0278364912469671 Please note that several errors were introduced to this article during copy editing. These were pointed out by the authors but unfortunately due to a publisher error were not corrected. SAGE Publications would like to apologise to the authors and readers for these errors: Third author Cristian Secchi's name was incorrectly spelt Christian Seccos. In the following places pacifying' should be passifying': Page 310 right hand column, 2nd paragraph Page 310, right hand column, 2nd paragraph Page 311, right hand column, last paragraph Page 312 left hand column, 2nd paragraph In the following places ith' should be i-th': Page 302, right hand column, 3(rd) paragraph, twice on the 20(th) line Page 306, left hand column, 1st paragraph, 9(th) line after equation 12 Page 306, right hand column, 1st paragraph, 15(th) line Page 307, right hand column, 2(nd) line after Figure 7 Page 309, right hand column, 2nd paragraph, 6(th) line Page 309, right hand column, 3rd paragraph, 12(th) line Page 310, left hand column, 1(st) paragraph in numbered list, 3(rd) line Page 313, left hand column, 1(st) paragraph, 9(th) line after equation 40. In the following places kth' should be k-th': Page 307, left hand column, last line Page 308, right hand column, 2(nd) paragraph, 4(th) line In the following places hth' should be h-th': Page 308, left hand column, 1(st) line after equation 21 In the following places jth' should be j-th: Page 309, right hand column, 2(nd) paragraph, 7(th) line In the following places one-hop' should be 1-hop': Page 303, right hand column, 1(st) 3rd line from top Page 308, right hand column, 3(rd) line below equation 27 and last line Page 309, left hand column, 4(th) paragraph, last line Page 309, right hand column, 3(rd) line from top Page 309, right hand column, 1(st) paragraph, last line Page 309, right hand column, 3(rd) paragraph, 2nd line
2013
- Guest Editorial for the Special Issue on Lagrangian and Hamiltonian methods for modelling and control
[Articolo su rivista]
A., Macchelli; Secchi, Cristian; A. J., van der Schaft
abstract
n.a.
2013
- Special Issue on Lagrangian and Hamiltonian Methods for Nonlinear Control
[Direzione o Responsabilità Riviste]
Secchi, Cristian; A., Macchelli; A. J., van der Schaft
abstract
2013
- Technological Roadmap to Boost the Introduction of AGVs in Industrial Applications
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; V., Digani; Secchi, Cristian; Cotena, Giuseppina; D., Ronzoni; M., Foppoli; F., Oleari
abstract
This paper describes systems of multiple Automated Guided Vehicles (AGVs) used in factory logistics for the transportation of goods. We describe currently applied solutions, highlighting the main issues that, so far, have prevented a pervasive diffusion of these systems. A roadmap of technological solutions is then drafted, to improve the performance of AGV systems and boost their wide application in factory logistics.
2013
- Towards decentralized coordination of multi robot systems in industrial environments: A hierarchical traffic control strategy
[Relazione in Atti di Convegno]
Digani, Valerio; Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper describes an innovative approach to manage multiple Automated Guided Vehicles (AGVs) in an industrial environment. The proposed approach is based on a two layer architecture for path planning. This architecture consists of a topological layer, composed by macro-cells, and of a route map layer in which the AGVs have to move along fixed paths. The traffic is managed in a decentralized manner. Each AGV computes autonomously its own path both at topological layer and at route map layer. The coordination among the AGVs is based on the negotiation of shared resources. An early phase of validation is provided by the simulation in a structured environment.
2012
- A Novel Inertial/RFID Based Localization Method for Autonomous Lawnmowers
[Relazione in Atti di Convegno]
Levratti, Alessio; Bonaiuti, Matteo; Secchi, Cristian; Fantuzzi, Cesare
abstract
Robotic lawnmowers currently available in the market cover their assigned area using a random reflection navigation strategy. While this strategy has been widely accepted for autonomous vacuum cleaning systems, it poses quality problems in outdoor applications since a randomic crossing of the garden can lead to an uneven mowing. In this paper we propose a localization algorithm based on a modified Constrained Kalman Filter that allows to implement an efficient navigation strategy and to increase the quality of service of the mower. This method properly merges data coming from an Inertial Measurement Unit (IMU) and from an RFID (Radio-Frequency IDentification) antenna with information given by the Hall sensors of the wheels of the robot. The proposed algorithm has been verified first by simulation, and then with experiments by building a prototype lawnmower robot.
2012
- An Inertial/RFID based localization method for autonomous lawnmowers
[Relazione in Atti di Convegno]
Levratti, A.; Bonaiuti, M.; Secchi, C.; Fantuzzi, C.
abstract
Robotic lawnmowers currently available in the market cover their assigned area using a random reflection navigation strategy. While this strategy has been widely accepted for autonomous vacuum cleaning systems, it poses quality problems in outdoor applications since a randomic crossing of the garden can lead to an uneven mowing. In this paper we propose a localization algorithm based on a modified Constrained Kalman Filter that allows to implement an efficient navigation strategy and to increase the quality of service of the mower. This method properly merges data coming from an Inertial Measurement Unit (IMU) and from an RFID (Radio-Frequency IDentification) antenna with information given by the Hall sensors of the wheels of the robot. The proposed algorithm has been verified first by simulation, and then with experiments by building a prototype lawnmower robot. © 2012 IFAC.
2012
- An algorithm to diagnose ball bearing faults in servomotors running arbitrary motion profiles
[Articolo su rivista]
Cocconcelli, Marco; L., Bassi; Secchi, Cristian; Fantuzzi, Cesare; Rubini, Riccardo
abstract
This paper describes a procedure to extend the scope of classical methods to detectball bearing faults (based on envelope analysis and fault frequencies identification)beyond their usual area of application. The objective of this procedure is to allowcondition-based monitoring of such bearings in servomotor applications, where typicallythe motor in its normal mode of operation has to follow a non-constant angularvelocity profile that may contain motion inversions. After describing and analyzingthe algorithm from a theoretical point of view, experimental results obtained on areal industrial application are presented and commented
2012
- Bilateral Shared Control : Balancing Autonomy and Human Assistance with a Group of Quadrotor UAVs
[Articolo su rivista]
A., Franchi; Secchi, Cristian; M., Ryll; H. H., Buelthoff; P., Robuffo Giordano
abstract
In this paper, we present a complete control frame- work and associated experimental testbed for the bilateral shared control of a group of quadrotor UAVs. This control architecture is applicable to any task and allows to integrate: i) a decen- tralized topological motion control (responsible for the mutual interactions in the UAV formation), ii) a human assistance module (allowing human intervention, whenever needed, on some aspects of the UAV group behavior), and iii) a force-feedback possibility (increasing the telepresence of the human assistants by providing suitable haptic cues informative of the UAV behavior). We will show, as worked-out case studies, how to specialize the topological motion controller to the relevant cases of constant, unconstrained and connected group topologies, and how to let a human operator intervening at the level of single UAVs or of the whole group dynamics. A detailed description of the experimental testbed is also provided with emphasis on the quadrotor UAV hardware and software architectures. Finally, the versatility of the proposed framework is demonstrated by means of experiments with real UAVs. Although quadrotors are used as actual robotic platforms, the proposed framework can be straightforwardly extended to many different kinds of UAVs with similar motion characteristics.
2012
- Bilateral Teleoperation of Groups of Mobile Robots with Time-Varying Topology
[Articolo su rivista]
A., Franchi; Secchi, Cristian; H. I., Son; H. H., Buelthoff; P., Robuffo Giordano
abstract
In this paper, a novel decentralized control strategy for bilaterally teleoperating heterogeneous groups of mobile robots from different domains (aerial, ground, marine, and underwater) is proposed. By using a decentralized control architecture, the group of robots, which is treated as the slave side, is made able to navigate in a cluttered environment while avoiding obstacles, interrobot collisions, and following the human motion commands. Simultaneously, the human operator acting on the master side is provided with a suitable force feedback informative of the group response and of the interaction with the surrounding environment. Using passivity-based techniques, we allow the behavior of the group to be as flexible as possible with arbitrary split and join events (e.g., due to interrobot visibility/packet losses or specific task requirements) while guaranteeing the stability of the system. We provide a rigorous analysis of the system stability and steady-state characteristics and validate performance through human/hardware-in-the-loop simulations by considering a heterogeneous fleet of unmanned aerial vehicles (UAVs) and unmanned ground vehicles as a case study. Finally, we also provide an experimental validation with four quadrotor UAVs.
2012
- Bilateral Teleoperation of a Group of UAVs with Communication Delays and Switching Topology
[Relazione in Atti di Convegno]
Secchi, Cristian; A., Franchi; H. H., Buelthoff; P., Robuffo Giordano
abstract
In this paper, we present a passivity-based de- centralized approach for bilaterally teleoperating a group of UAVs composing the slave side of the teleoperation system. In particular, we explicitly consider the presence of time delays, both among the master and slave, and within UAVs composing the group. Our focus is on analyzing suitable (passive) strategies that allow a stable teloperation of the group despite presence of delays, while still ensuring high flexibility to the group topology (e.g., possibility to autonomously split or join during the motion). The performance and soundness of the approach is validated by means of human/hardware-in-the-loop simulations (HHIL).
2012
- Bilateral teleoperation of groups of UAVs with decentralized connectivity maintenance
[Relazione in Atti di Convegno]
Giordano, P. R.; Franchi, A.; Secchi, C.; Bulthoff, H. H.
abstract
In this paper, we present a decentralized passivitybased control strategy for the bilateral teleoperation of a group of Unmanned Aerial Vehicles (UAVs). The human operator at the master side can command the group motion and receive suitable force cues informative about the remote environment. By properly controlling the energy exchanged within the slave side (the UAV group), we guarantee that the connectivity of the group is preserved and we prevent inter-agent and obstacle collisions. At the same time, we allow the behavior of the UAVs to be as flexible as possible with arbitrary split and join maneuvers. The results of the paper are validated by means of human/hardwarein- the-loop (HHIL) simulations.
2012
- Decentralized Connectivity Maintenance for Networked Lagrangian Dynamical Systems
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; N., Chopra
abstract
In order to accomplish cooperative tasks, multi– robot systems are required to communicate among each other. Thus, maintaining the connectivity of the communication graph is a fundamental issue. Connectivity maintenance has been extensively studied in the last few years, but generally con- sidering only kinematic agents. In this paper we will introduce a control strategy that, exploiting a decentralized procedure for the estimation of the algebraic connectivity of the graph, ensures the connectivity maintenance for groups of Lagrangian systems. The control strategy is validated by means of analytical proofs and simulation results.
2012
- Decentralized Global Connectivity Maintenance for Interconnected Lagrangian Systems with Communication Delays
[Relazione in Atti di Convegno]
Secchi, Cristian; Sabattini, Lorenzo; Fantuzzi, Cesare
abstract
n order to accomplish cooperative tasks, multi robot systems are required to communicate among each other. Thus, maintaining the connectivity of the communication graph is a fundamental issue. In this paper we extend the connectivity maintenance control strategy introduced in (Sabattini et al., 2012), in order to explicitly take into account the presence of communication delays. When dealing with interconnected robotic systems, in fact, assuming instantaneous exchange of data is often unrealistic. For this reason, we provide a solution to the connectivity maintenance problem for interconnected Lagrangian dynamical agents, in the presence of communication delays.
2012
- Enhanced Connectivity Maintenance for Multi-Robot Systems
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; A., Gasparri; Secchi, Cristian; N., Chopra
abstract
In this work, the decentralized control law proposed in [Sabattini et al., 2011b] for multi-robot connectivity maintenance is enhanced by means of a selective action. The idea is to identify critical agents, i.e. agents for which a disconnection might cause the split of the communication graph, and limit the control action to those agents. The objective is twofold: to reduce the control effort introduced by the connectivity maintenance control action as well as to avoid unnecessary action of the connectivity maintenance controller, thus reducing its effect on the overall performances of the system. A theoretical analysis of the proposed control law is discussed. Simulations along with experimental results are given to corroborate the theoretical results.
2012
- Experimental comparison of 3D vision sensors for mobile robot localization for industrial application: stereo–camera and RGB–D sensor
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Levratti, Alessio; F., Venturi; E., Amplo; Fantuzzi, Cesare; Secchi, Cristian
abstract
While RGB–D sensors are becoming more and more popular in mobile robotics laboratories, they are usually not yet adopted for industrial applications. In fact, in this field, depth measurements are generally acquired by means of laser scanners and, when visual information is needed, by means of stereo– cameras. The aim of this paper is to perform an experimental validation, to compare the performance of a stereo–camera and an RGB–D sensor, in a specific application: mobile robot localization for industrial applications. Experiments are performed exploiting artificial landmarks (defined by a self–similar pattern), placed in known positions in the environment.
2012
- Online Trajectory Generation for Mobile Robots with Kinodynamic Constraints and Embedded Control Systems
[Relazione in Atti di Convegno]
M., Bonfé; Secchi, Cristian; E., Scioni
abstract
The paper describes trajectory generation and tracking control algorithms, respectively based on nonlinear filtering and dynamic feedback linearization, for mobile robots. A main feature of proposed algorithms is that they are suitable for the implementation on embedded systems with limited computational resources. The trajectory generator is based on nonlinear filters and logic-based management of reference inputs and dynamic constraints, allowing online smoothing of straight-line reference paths. Sparse via-points along a path can be assigned by a global planner based on obstacle avoidance algorithms and can be changed at any time during motion. Moreover, the trajectory generated by the nonlinear filter can be fed into a control loop based on the dynamic model of the robot, so that accurate tracking can be achieved. The paper includes practical remarks for efficient fixed-point implementation of the proposed trajectory generator.
2012
- Towards Automated Surgical Robotics: a Requirements Engineering Approach
[Relazione in Atti di Convegno]
M., Bonfé; F., Boriero; R., Dodi; P., Fiorini; A., Morandi; R., Muradore; L., Pasquale; A., Sanna; Secchi, Cristian
abstract
The paper describes a design specification process for the development of novel and intelligent surgical robots. Nowadays, surgical robots are usually controlled by the sur- geons manually by using teleoperation. The possibility to carry out simple surgical actions automatically has been the subject of academical research, but very few real-world applications exist. The main objective of this research is to address realistic case studies and develop systems and methods to provide surgeons with autonomous robotic assistants, performing basic surgical actions by combining sensing, dexterity and cognitive capabilities. This goal can only be achieved by means of a formal and rigorous assesment of surgical requirements, so that they can be analysed and translated into behavioral specifications for an autonomous robotic system. Therefore, the paper describes the application of Requirements Engineering to surgical knowledge formalization and propose a methodology for the transformation of requirements into formal models of robotic tasks.
2011
- A Design Pattern for translating UML software models into IEC 61131-3 Programming Languages
[Relazione in Atti di Convegno]
Fantuzzi, Cesare; M., Bonfè; F., Fanfoni; Secchi, Cristian
abstract
The paper deal with a deep analysis and application of object-oriented methodologies for the design process of industrial machine controllers. The process pass thought the phases of (1) conceptual model development of the software artifacts, and (2) model code deployment for the automation system target, which is in general a Programmable Logic Controller (PLC) compliant with the international standard IEC 61131-3 for programming languages. The paper describes a design pattern for the software conceptual model deployment, with a particular emphasis on practical requirements enforced by PLC of different brands. In fact, IEC 61131-3 compliance provides a common ``look-and-feel'' for programming languages, but does not guarantee straightforward code portability between different PLC vendors. The paper has a great focus on applications and provides an example, based on a generic flow-pack machine, to better explain the proposed methodology.
2011
- A Graph-Based Collision- Free Distributed Formation Control Strategy
[Relazione in Atti di Convegno]
R., Falconi; Sabattini, Lorenzo; Secchi, Cristian; C., Melchiorri; Fantuzzi, Cesare
abstract
n this paper we describe a consensus based control strategy to obtain a formation of groups of mobile robots. Weighted graphs are used to obtain the desired formation-shape while avoiding collisions among the robots. Since mobile robots usually move in unknown and unstructured environments, we show how to extend our control strategy to make the robots avoid collision with obstacles as well. To validate our control strategy, we provide both analytical proofs and simulative and experimental results.
2011
- A Passivity-Based Decentralized Approach for the Bilateral Teleoperation of a Group of UAVs with Switching Topology
[Relazione in Atti di Convegno]
A., Franchi; P., Robuffo Giordano; Secchi, Cristian; H. I., Son; H. H., Bülthoff
abstract
In this paper, a novel distributed control strategy for teleoperating a fleet of Unmanned Aerial Vehicles (UAVs) is proposed. Using passivity based techniques, we allow the behavior of the UAVs to be as flexible as possible with arbitrary split and join decisions while guaranteeing stability of the system. Furthermore, the overall teleoperation system is also made passive and, therefore, characterized by a stable behavior both in free motion and when interacting with unknown passive obstacles. The performance of the system is validated through semi-experiments.
2011
- A SysML based methodology for manufacturing system modeling and design
[Articolo su rivista]
L., Bassi; Secchi, Cristian; Fantuzzi, Cesare; M., Bonfé
abstract
This paper describes a modeling methodology to support the design process of complex systems. The main challenge in modern industrial applications is the sheer volume of data involved in the design process. While using high-level abstraction is necessary to manage this data and analyze the system “as a whole,” designers need also to retain all the low-level information of the system, in order to be able to perform optimizations and modifications at later times. The solution proposed here is to use a hierarchy of models, each one describing the system at different levels of abstraction, and arrange them in such a way that it is possible to easily “map” each level onto the others. The topmost layer of the system description is expressed in System Modeling Language, a general-purpose modeling language based on Unified Modeling Language.
2011
- AGV Global Localization Using Indistinguishable Artificial Landmarks
[Relazione in Atti di Convegno]
D., Ronzoni; R., Olmi; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we consider the global localization problem for an industrial AGV moving in a known environment. The problem consists of determining the pose of the vehicle without any prior information about its location. The vehicle is supposed to be equipped with a laser scanner that allows to measure the range and bearing of the vehicle with respect to a set of anonymous landmarks. A map with the positions of all landmarks in the environment is available to the localization system. We propose a novel algorithm for AGV self-localization based on landmarks identification that can take into account also false detections, very common in industrial environments. The pose is computed with a single scan (2D), without any sensor fusion. The performance of the proposed strategy is shown both by simulations and experiments on real industrial plants.
2011
- An Efficient Control Strategy for the Traffic Coordination of AGVs
[Relazione in Atti di Convegno]
R., Olmi; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we propose an algorithm for coordinating a fleet of Automated Guided Vehicles (AGVs) that go through predefined paths in a dynamic industrial environment. Coordination diagrams are used to define a mapping between the configuration space of the fleet and a set of motion constraints that the vehicles must satisfy in order to avoid mutual collisions. The motion actions that maximize the advancement of the fleet while respecting the constraints are determined by a polynomial time heuristic algorithm.
2011
- Arbitrary shaped formations of mobile robots: Artificial Potential fields and coordinate transformation
[Articolo su rivista]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we describe a novel decentralized control strategy to realize formations of mobile robots. We first describe how to design artificial potential fields to ob- tain a formation with the shape of a regular polygon. We provide a formal proof of the asymptotic stability of the sys- tem, based on the definition of a proper Lyapunov function. We also prove that our control strategy is not affected by the problem of local minima. Then, we exploit a bijective coordinate transformation to deform the polygonal forma- tion, thus obtaining a completely arbitrarily shaped forma- tion. Simulations and experimental tests are provided to val- idate the control strategy.
2011
- Bilateral Telemanipulation with time delays: A two-layer approach combining passivity and transparency
[Articolo su rivista]
M., Franken; S., Stramigioli; S., Misra; Secchi, Cristian; A., Macchelli
abstract
In this paper, a two-layer approach is presented to guarantee the stable behavior of bilateral telemanipulation systems in the presence of time-varying destabilizing factors such as hard contacts, relaxed user grasps, stiff control settings, and/or communication delays. The approach splits the control architecture into two separate layers. The hierarchical top layer is used to implement a strategy that addresses the desired transparency, and the lower layer ensures that no “virtual” energy is generated. This means that any bilateral controller can be implemented in a passive manner. Separate communication channels connect the layers at the slave and master sides so that information related to exchanged energy is completely separated from information about the desired behavior. Furthermore, the proposed implementation does not depend on any type of assumption about the time delay in the communication channel. By complete separation of the properties of passivity and transparency, each layer can accommodate any number of different implementations that allow for almost independent optimization. Experimental results are presented, which highlight the benefit of the proposed framework.
2011
- Coordination of Industrial AGVs
[Articolo su rivista]
R., Olmi; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper, we propose an algorithm for coordinating a group of mobile robots that go through predefined paths in a dynamic industrial environment. Coordination diagrams are used for representing the possible collisions among the vehicles. We exploit this information for developing a centralised and incremental planning algorithm that allows to coordinate the vehicles and to take into account unexpected events that can occur in an industrial environment. Simulation tests have been executed in order to compare the performance of our algorithm with the one currently implemented by the company.
2011
- Distributed Control of Multi-Robot Systems with Global Connectivity Maintenance
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; N., Chopra; Secchi, Cristian
abstract
In this paper we present a decentralized control strategy for the connectivity maintenance for groups of mobile robots performing some desired task. Exploiting a completely decentralized estimation strategy for the algebraic connectivity of the graph, we prove the connectivity maintenance property in the general case, i.e. in presence of a generic (bounded) additional control term. Then, we address two specific decentralized control applications: rendezvous and formation control. We analytically prove that our control strategy ensures the global connectivity maintenance, while preserving the convergence properties of the rendezvous and formation controllers respectively. Simulations and experimental results are presented as well, in order to show the effectiveness of the proposed control law.
2011
- Experiments of Passivity-Based Bilateral Aerial Teleoperation of a Group of UAVs with Decentralized Velocity Synchronization
[Relazione in Atti di Convegno]
P., Robuffo Giordano; A., Franchi; Secchi, Cristian; H. H., Buelthoff
abstract
In this paper, we present an experimental validation of a novel decentralized passivity-based control strategy for teleoperating a group of Unmanned Aerial Vehicles (UAVs): the slave side, consisting of the UAVs, is endowed with large group autonomy by allowing time-varying topology and interrobot/obstacle collision avoidance. The master side, represented by a human operator, controls the group motion and receives suitable force feedback cues informing her/him about the remote slave motion status. Passivity theory is exploited for guaranteeing stability of the slave side and of the overall teleoperation channel. Results of experiments involving the use of 4 quadcopters are reported and discussed, confirming the soundness of the paper theoretical claims.
2011
- On Decentralized Connectivity Maintenance for Mobile Robotic System
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; N., Chopra; Secchi, Cristian
abstract
To accomplish cooperative tasks, robotic systems are often required to communicate with each other. Thus, maintaining connectivity of the interagent communication graph is a fundamental issue in the field of multi-robot systems. In this paper we present a completely decentralized control strategy for global connectivity maintenance of the interagent communication graph. We describe a gradient-based control strategy that exploits decentralized estimation of the algebraic connectivity. The proposed control algorithm guarantees the global connectivity of the communication graph without requiring maintenance of the local connectivity between the robotic systems. The control strategy is validated by means of an analytical proof and simulative results.
2011
- Passivity-Based Decentralized Connectivity Maintenance in the Bilateral Teleoperation of Multiple UAVs
[Relazione in Atti di Convegno]
P., Robuffo Giordano; A., Franchi; Secchi, Cristian; H. H., Buelthoff
abstract
In this paper, we present a decentralized passivity- based control strategy for the bilateral teleoperation of a group of Unmanned Aerial Vehicles (UAVs). The human operator at the master side can command the group motion and receive suitable force cues informative about the remote environment. By properly controlling the energy exchanged within the slave side (the UAV group), we guarantee that the connectivity of the group is preserved and we prevent inter-agent and obstacle collisions. At the same time, we allow the behavior of the UAVs to be as flexible as possible with arbitrary split and join maneuvers. The results of the paper are validated by means of human/hardware- in-the-loop (HHIL) simulations.
2011
- Towards Bilateral Teleoperation of Multi-Robot Systems
[Relazione in Atti di Convegno]
P., Robuffo Giordano; A., Franchi; H. I., Son; Secchi, Cristian; D. J., Lee; H. H., Buelthoff
abstract
2011
- Traffic Control of AGVs in Automatic Warehouses: the TRAFCON Experiment
[Relazione in Atti di Convegno]
Secchi, Cristian
abstract
This paper illustrates the TRAFCON experiment and its main results towards the coordination of a group of AGVs in an automatic warehouse.
2011
- Tutorial: Control issues in haptic teleoperation
[Relazione in Atti di Convegno]
Peer, A.; Secchi, C.; Sato, K.; Cavusoglu, C.
abstract
Telerobotics is one of the most traditional fields of robotics and it played a crucial role in the history of robotics and of the mankind, especially in the areas of space and undersea exploration and of remote material handling. On the other hand, teleoperation is still a very active research area and many problems are still open. In particular, the design of the control strategy for coupling local and remote site is of paramount importance for implementing telepresence, namely the feeling of being directly interacting with the remote environment. The IEEE RAS Technical Committee on Telerobotics would like to propose a half-day tutorial for illustrating several successful control strategies for implementing high performance bilateral teleoperation systems. © 2011 IEEE.
2010
- An Algorithm to Diagnose Ball Bearings Faults in Servomotors Running Arbitrary Motion Profiles
[Relazione in Atti di Convegno]
L., Bassi; Cocconcelli, Marco; Secchi, Cristian; Rubini, Riccardo; Fantuzzi, Cesare
abstract
-
2010
- An engineering process for the mechatronic development of industrial automation systems
[Relazione in Atti di Convegno]
Fantuzzi, Cesare; F., Fanfoni; Secchi, Cristian; M., Bonfé
abstract
This paper deals with the development process of an industrial application for the manufacturing of artefacts and products. In particular, a new engineering process tackling the whole machine life-cycle, from the user requirements capture, the project conceptual development to the final machine delivery and acceptance tests, is presented. The process is particularly tailored to the development of automated machines for the beverage and liquid food packaging market, and it is illustrated with a real case study developed in cooperation with a market leader machine manufacturer.
2010
- Bird's - Eye View Image for the Localization of a Mobile Robot by Means of Trilateration
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare; A., Stefani
abstract
In this paper we introduce a method for the localization of a low–cost mobile robot,based on the use of a monocular camera. We consider a robot moving in a bi–dimensionalenvironment, where some landmarks are placed in known positions. The acquired image of theenvironment is converted into a bird’s–eye view image, used to measure the distance of the robotfrom the landmarks, to compute the robot’s position by means of trilateration. The proposedstrategy is able to compute both the position and the orientation of the robot.
2010
- Bridging the gap between passivity and transparency
[Relazione in Atti di Convegno]
M., Franken; S., Stramigioli; R., Reilink; Secchi, Cristian; A., Macchelli
abstract
In this paper a structure will be given which in aremarkably simple way offers a solution to the implementationof different telemanipulation schemes for discrete time varyingdelays by preserving passivity and allowing the highest transparencypossible. This is achieved by splitting the communicationchannel in two separate ones, one for the energy balance whichwill ensure passivity and one for the haptic information betweenmaster and slave and which will address transparency. Theauthors believe that this structure is the most general up todate which preserves passivity under discrete time varying delaysallowing different control schemes to address transparency.
2010
- Coordinating multiple robots with assigned paths
[Relazione in Atti di Convegno]
R., Olmi; Secchi, Cristian; Fantuzzi, Cesare
abstract
This paper describes a method for coordinating the motions of a group of robotsfollowing predefined paths in a common workspace. Coordination Diagrams (CD) are used forrepresenting the possible collisions among the robots. We propose an algorithm that computesa complete coordination plan for the overall missions that each vehicle have to execute. Thealgorithm generates a set of possible coordination plans and then gives the optimal one. Previousworks apply traditional path planning techniques (such as D* or A*) to compute a coordinatedmotion. However these techniques do not take into account the fact that the CD has a cylindricalstructure. This important features enables our algorithm to explore the CD in a more efficientlyway.
2010
- Coordinating the motion of multiple AGVs in automatic warehouses
[Relazione in Atti di Convegno]
R., Olmi; Secchi, Cristian; Fantuzzi, Cesare
abstract
2010
- Coordination of multiple robots with assigned paths
[Relazione in Atti di Convegno]
Olmi, R.; Secchi, C.; Fantuzzi, C.
abstract
This paper describes a method for coordinating the motions of a group of robots following predefined paths in a common workspace. Coordination Diagrams (CD) are used for representing the possible collisions among the robots. We propose an algorithm that computes a complete coordination plan for the overall missions that each vehicle has to execute. The algorithm generates a set of possible coordination plans and then gives the optimal one. Previous works apply traditional path planning techniques (such as D* or A*) to compute a coordinated motion. However these techniques do not take into account the fact that the CD has a cylindrical structure. This features enables our algorithm to explore the CD in a more efficient way.
2010
- Online Smooth Trajectory Planning for Mobile Robots by Means of Nonlinear Filters
[Relazione in Atti di Convegno]
M., Bonfé; Secchi, Cristian
abstract
The paper presents a nonlinear filtering technique that can be adopted to generate smooth trajectories for mobile robotic applications. The proposed trajectory planner can be fully executed online by the robot control system, thanks to its inherently discrete-time behavior and to its limited computational requirement. The outputs of the nonlinear filter used as a trajectory planner include the derivatives of the desired position in the cartesian plane up to the third order. This allows the implementation of feedback linearization control schemes that can transform the dynamics of a mobile robot in a double chain of three integrators, exploiting the highest derivative of the filter’s output as a feedforward action. Finally, the paper reports experimental results obtained by the full implementation of the proposed trajectory planning and control scheme on a real unicycle-like robot.
2010
- Perception-centric Force Scaling in Bilateral Teleoperation
[Articolo su rivista]
D., Botturi; M., Vicentini; M., Righele; Secchi, Cristian
abstract
In this work we propose a control architecture that leads to an intrinsically stable bilateral teleoperation system, where the telepresence of the user is improved in terms of remote force discrimination. We iden- tify, through a set of psychophysical experiments, a variable force scaling matrix that improves the oper- ator’s feeling of the remote environment. We show that it is possible to build a passive control scheme that embeds this perception-centric scaling. Finally, an experiment is presented to validate the results pro- posed in the paper.
2010
- SaBot: A scalable architecture for Web-enabled Mobile Robots
[Relazione in Atti di Convegno]
M., Bonfé; E., Piccinini; Secchi, Cristian
abstract
The paper presents the architecture of an experimental mobile robotic platform, which has beendesigned specifying interoperability between multiple robots as a main objective. In particular,novel software technologies based onWeb services have been exploited in order to support mobilerobots with efficient and extensible messaging, data-sharing and distributed task managementcapabilities. The basic components of the proposed architecture have been implemented andtested on a demonstrative robotic setup, that will be fully described in the paper. However, theaim of the proposal is to contribute to future Web-based interoperability between mobile robotsemployed in either industrial or human service applications.
2010
- Special Issue on Design and Control Methodologies in Telerobotics
[Direzione o Responsabilità Riviste]
Secchi, Cristian; N., Chopra; A., Peer
abstract
2010
- Tracking of Closed-Curve Trajectories for Multi-Robot Systems
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare; D., de Macedo Possamai
abstract
In this paper we address the trajectory tracking problem for groups of mobile robots. We consider trajecto- ries described by completely arbitrary shaped closed curves. The proposed control strategy is a completely decentralized algorithm, and does not require any global synchronization. The desired behavior is obtained by means of some properly designed artificial potential functions.
2009
- A Coordination Technique for Automatic Guided Vehicles in an Industrial Environment
[Relazione in Atti di Convegno]
Olmi, Roberto; Secchi, Cristian; Fantuzzi, Cesare
abstract
{One of the most challenging steps of a simulation study is the experiments analysis since it provides the information necessary to make decision regarding project objectives. As a matter of fact, a very common practice is to carry out an arbitrary number of simulation runs of arbitrary length and then to perform inference on the simulation results, treating them as the ``true'' model output. The aim of this paper is to propose an innovative methodology to investigate simulation outputs in order to identify ``sustainable target'' for the system and express it as a point value rather than as a confidence interval. For this purpose, a decision support tool is then proposed, it takes as input the process output data of observed samples and provides as result the achievable targets for each couple of replication number and replication length by using the classical statistical concepts of type-I and type-II error
2009
- A design pattern for model based software development for automatic machinery
[Relazione in Atti di Convegno]
Fantuzzi, Cesare; M., Bonfé; Secchi, Cristian
abstract
The paper presents the results of the application of object-oriented modeling techniques to thecontrol software design of complex manufacturing systems, with particular focus on automaticmachineries for production and packaging of food stu, as milk, snacks, etc.In this application elds there are some peculiar problems to tackle in order to develop eectivesoftware control solutions, as for example the exception handling caused by product or packagingmaterial jam, the Human Machine Interface, the recipe production management etc.The goal of this paper is to introduce design patterns developed in the framework of UML appliedto the development of automatic machineries software, aiming to dene a set of predenedmodeling solutions to some class of recurrent design problems.
2009
- Comparison Between Time-Frequency Techniques to Predict Ball Bearing Fault in Drives Executing Arbitrary Motion Profiles
[Relazione in Atti di Convegno]
Cocconcelli, Marco; Secchi, Cristian; Rubini, Riccardo; Fantuzzi, Cesare; Bassi, L.
abstract
In this paper Wavelet Transform (WT) and Hilbert-Huang Transform (HHT) are used as bearing diagnostics tools in drives executing arbitrary motion profiles. This field is increasingly drawing the attention of the industries because the modern electric motors work as electric cams inducing the shaft to move with a cyclic variable-velocity profile. The literature papers take into account only a constant velocity profile and they are not suitable for such applications. In fact literature methods analyse the signal only in the frequency domain, while in variable-velocity condition the bearing diagnostics should be performed in time domain. Both WT and HHT are time-frequency techniques which describe an input signal as a sum of specific functions. These functions are compared with a signal which simulates the expected vibrations of a bearing with a given fault, e.g. on the outer race. The comparison is done through a cross-correlation between the expected signal and the time-frequency techniques output. WT and HHT are used separately in an industrial case, which consists in bearing fault prediction in an automated packaging machine. In the end of the paper the WT and HHT results are discussed to analyse the different responses.
2009
- Formation Control over Delayed Communication Networks
[Relazione in Atti di Convegno]
Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we address the problem of formation control of a group ofrobots that exchange information over a communication network characterized by anon negligible delay.We consider the Virtual Body Artificial Potential approach forstabilizing a group of robots at a desired formation. We show that it is possible tomodel the controlled group of robots as a port-Hamiltonian system and we exploitthe scattering framework to achieve a passive behavior of the controlled system andto stabilize the robots in the desired formation independently of any communicationdelay.
2009
- Perception-Centric Force Scaling Function for Stable Bilateral Interaction
[Relazione in Atti di Convegno]
Botturi, D; Galvan, S; Vicentini, M; Secchi, Cristian
abstract
In this paper a force scaling function for an haptic system is the output of the psychophysics experiments that have been carried out with the aim of better understanding the human perception capabilities. The experimental work consists in measuring the differential thresholds of force perception applied to the hand-arm system. These findings support our claim that the human perception of forces and torques depends on force intensity and works differently along different directions, thus suggesting that perception can be enhanced by suitable scaling. We have identified a scaling function for each direction and we have shown that this variable scalings can be safely embedded in a passivity based teleoperation system in order to improve the feeling perceived by the user during the interaction with remote environments.
2009
- Potential Based Control Strategy for Arbitrary Shape Formations of Mobile Robots
[Relazione in Atti di Convegno]
Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we describe a novel decentralized control strategy to realize formations of mobile robots. We first describe a methodology to obtain a formation with the shape of a regular polygon. Then, applying a bijective coordinates transformation, we show how to obtain a formation with an arbitrary shape. Our control strategy is based on the interaction of some artificial potential fields, but it is not affected by the problem of local minima.
2008
- A Force Dependent Scaling for Improving the Human Perception in Bilateral Teleoperation
[Relazione in Atti di Convegno]
Botturi, D; Galvan, S; Secchi, Cristian
abstract
In this paper a scaling function for an hapticsystem is the output of the psychophysics experiments that havebeen carried out with the aim of better understanding the humanperception capabilities. The experimental work consists inmeasuring the differential thresholds of force perception appliedto the hand-arm system. These findings support our claim thatthe human perception of forces and torques depends on forceintensity and works differently along different directions, thussuggesting that perception can be enhanced by suitable scaling.We have identified a scaling function for each direction and wehave shown that this variable scalings can be safely embeddedin a passivity based teleoperation system in order to improvethe feeling perceived by the user during the interaction withremote environments.
2008
- An analytical model for automated packaging lines design
[Relazione in Atti di Convegno]
Gebennini, Elisa; Grassi, Andrea; Secchi, Cristian; Fantuzzi, Cesare
abstract
The problem of deriving a probabilistic mathematical model of an industrial production line is addressed in this paper. In particular, the analysis of a Tetra Pak liquid foodstuff packaging line has been developed as application of the modeling theory. Tetra Pak's package forming machine works on the basis of a continuous process which cannot be interrupted without production wasting. Production buffer are used to decouple package forming machine with following (downstream) machines (e.g. straw applicator, film wrapper, etc.) to avoid forming machine forced stoppage because downstream machine stoppage. The paper presents a new analytical approach for the packaging forming machine restart control policy based on buffer level.
2008
- Authors’ reply to “Comments on ‘Object-Oriented Modeling of Complex Mechatronic Components for the Manufacturing Industry’
[Articolo su rivista]
Secchi, Cristian; M., Bonfé; Fantuzzi, Cesare; R., Borsari; D., Borghi
abstract
In his comments to our paper published on the IEEE Transactions on Mechatronics (Vol. 12, no. 6, pp. 696-702), Kleanthis Thramboulidis points out many issues related to the application of the Object-Oriented modeling approach proposed in the paper. The comments of Thramboulidis are relevant and properly referenced, especially considering the section about UML, its variants (i.e. UML 1.4, UML-RT, UML 2.0) and the conceptual elements of component based design. However, we believe that the author of the comments has focused his attention too much on the software implementation aspects, including engineering tools and run-time execution frameworks for the control software, which are actually outside the scope of the original paper. In this reply, we aim to emphasize the main contribution of the paper and analyse the issues raised in the comments, with particular regard on our plan to address them in future works.
2008
- Compensation of position errors in passivity based teleoperation over packet switched communication
[Relazione in Atti di Convegno]
Secchi, C.; Stramigioli, S.; Fantuzzi, C.
abstract
Because of the use of scattering based communication channels, passivity based telemanipulation systems can be subject to a steady state position error between master and slave robots. In this paper, we consider the case in which the passive master and slave sides communicate through a packet switched communication channel (e.g. Internet) and we provide a modification of the slave impedance controller for compensating the steady state position error arising in free motion because of packets loss. Copyright © 2007 International Federation of Automatic Control All Rights Reserved.
2008
- Compensation of position errors in passivity based teleoperation over packet switched communication networks
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S; Fantuzzi, Cesare
abstract
Invited paper nella sessione intitolata “Putting Energy back in Robotics”.
2008
- Coordination of Multiple AGVs in an Industrial Application
[Relazione in Atti di Convegno]
Olmi, R; Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we propose a methodology for coordinating a group of mobile robots following predefined paths in a dynamic industrial environment. Coordination diagrams are used for representing the possible collisions among the robots. Exploiting the structure of the industrial application we are dealing with, we propose an algorithm for efficiently composing the coordination diagram. Furthermore, we classify the possible collisions that can take place and the induced geometry of the resulting coordination diagram. Finally, we exploit this information for developing a planning algorithm that allows to coordinate the robots and to take into account unexpected events that can occur in an industrial environment.
2008
- Formation Control Over Delayed Communication Networks
[Relazione in Atti di Convegno]
Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we address the problem of formation control of a group of robots that exchange information over a delayed communication network. We consider the Virtual Body Artificial Potential approach for stabilizing a group of robots at a desired formation. We show that it is possible to model the controlled system as a set of elements exchanging energy along a power preserving interconnection structure. We exploit the scattering framework to stabilize the robots in the desired formation independently of any delay in the communication of the information.
2008
- Predictive maintenance of ball bearings for machines rotating with arbitrary velocity profiles
[Relazione in Atti di Convegno]
Cocconcelli, Marco; Secchi, Cristian; Rubini, Riccardo; Fantuzzi, Cesare; Bassi, L.
abstract
Recent research and development on direct–drive motor technology and on their control system push forwardthe application of these devices as electric cams in a large numbers of industrial applications, such as examplemotion control system for packaging machineries. Performances of these devices are much higher than themechanical solutions for machine motion, in terms of precision and operational speed, and, of course, intime required to reconfigure the motion profile.However, classical approaches to the ball bearing diagnosis that use analysis of vibration signals are notlonger applicable, as they have been developed on the hypothesis of drive constant speed. In fact, in mostof the current industrial application, the control system drives the motor to follow a complex and cyclic (i.e.motor shaft reverses its motion direction at each operational cycle) non constant speed motion profile.In those application, even Computed Order Tracking [1] (COT), which is the main fault bearing diagnosistechnique used in non-constant velocity applications, fails to detect incipient faults, as highlighted by Fyfeand Munck in [2].This paper presents a new procedure that modifies the COT to be successfully applicable to the diagnosisproblem of ball bearings in variable speed motion applications.
2008
- Transparency in Port-Hamiltonian-Based Telemanipulation
[Articolo su rivista]
Secchi, Cristian; S., Stramigioli; Fantuzzi, Cesare
abstract
After stability, transparency is themajor issue in the design of a telemanipulation system. In this paper, we exploit the behavioral approach in order to provide an index for the evaluation of transparency in port-Hamiltonian-based teleoperators. Furthermore, we provide a transparency analysis of packet switching scattering-based communication channels.
2008
- Variable Delay in Scaled Port-Hamiltonian Telemanipulation
[Articolo su rivista]
Secchi, Cristian; S., Stramigioli; Fantuzzi, Cesare
abstract
In several applications involving bilateral telemanipulation, master and slave robots act at different power scales (e.g. telesurgery, micromanipulation). Scaling forces and velocities means scaling the power that is exchanged between master and slave sides through the communication channel. In this paper weshow how it is possible to embed power scaling in the scattering based communication channel used in port-Hamiltonian based telemanipulation. Furthermore, a strategy for passively dealing with variable communication delay is proposed in order to allow scaled teleoperation over packet switched networksas Internet.
2008
- Verification of Fault Tolerance of Discrete-Event Object-Oriented Models using Model Checking
[Relazione in Atti di Convegno]
Bonfe', M; Fantuzzi, Cesare; Secchi, Cristian
abstract
The Object-Oriented (O-O) approach has been recently used in the industrialautomation to design logic control systems, thanks to the features of specification languages(e.g. UML) that can help to describe event-based behavioral requirements. In this paper, weaim to formalise an O-O framework for the design of modular logic controllers, in which faultsoccurring in the plant can alter the behavior of closed-loop system. Given the formal model ofthe system in terms of Kripke structures, it is possible to verify with model checking that evenin case of faults the system do not violate given safety and liveness properties. Moreover, we willconsider the case in which an O-O logic controller is refined applying the so-called “design-by-extension” mechanism, in which case it is important to verify that the fault tolerance propertyis inherited by the refined system.
2008
- Virtual Fixtures for Secondary Tasks
[Relazione in Atti di Convegno]
G., Lefemine; G., Pedrini; Secchi, Cristian; F., Tesauri; S., Marzani
abstract
The insertion of data in personal devices (e.g. mobile phones, GPS devices)tends to distract us from the primary task (e.g driving) that we are executingbecause of the necessity of deviating our visual attention to a secondary task. In thiswork we have tested the benefits introduced by the haptic feedback as a facility for avery common secondary tasks, namely the insertion of strings in an input device. Experimentsdemonstrate that the presence of virtual fixtures improves performancesduring input tasks and decreases the distraction of the user from the primary task.
2007
- A port-Hamiltonian approach to the control of interaction
[Capitolo/Saggio]
Secchi, C.; Fantuzzi, C.; Stramigioli, S.
abstract
In many applications, a robot has to interact with the surrounding environment in order to perform some useful task. When a manipulator interacts with an object a very profound change occurs. In fact, before the contact, the controller has to control only the motion of the robot; after the contact, the manipulator dynamically interacts with the environment and the controller has to manage a new dynamical system made up by the robot coupled with the environment. It has been proven in [328] that even if the controlled robot is stable in case of free motion, its behavior could become unstable when there is a contact with the environment. © 2007 Springer-Verlag Berlin Heidelberg.
2007
- Control of Interactive Robotic Interfaces: a port-Hamiltonian approach
[Monografia/Trattato scientifico]
Secchi, Cristian; S., Stramigioli; Fantuzzi, Cesare
abstract
This monograph deals with energy based control of interactive robotic interfaces and the port-Hamiltonian framework is exploited both for modeling and controlling interactive robotic interfaces. Using the port-Hamiltonian framework, it is possible to identify the energetic properties that have to be controlled in order to achieve a desired interactive behavior and it is possible to build a port-Hamiltonian controller that properly regulates the robotic interface by shaping its energetic properties.Thanks to its generality, the port-Hamiltonian formalism allows to model and control also complex interactive robotic interfaces in a very natural way. In this book, a port-Hamiltonian approach for regulating the interaction between a robot and a local environment, a virtual environment (i.e. haptic interfaces) and a remote environment (i.e. bilateral telemanipulation systems) is developed.
2007
- Control of port-Hamiltonian systems
[Capitolo/Saggio]
Secchi, C.; Fantuzzi, C.; Stramigioli, S.
abstract
Energy plays a central role in the control of physical systems since the "shape" of the energy is related to the stability properties of the system. In fact, it is well known from physics, that every configuration characterized by a (local) minimum of the energy exhibits a (locally) stable behavior. Unfortunately the configuration that naturally corresponds to a minimum of the energy is very seldom the desired configuration for the system. © 2007 Springer-Verlag Berlin Heidelberg.
2007
- Discussion on "On preserving passivity in sampled-data linear systems"
[Articolo su rivista]
Secchi, Cristian; S., Stramigioli
abstract
non presente
2007
- Energy Shaping over Networks for Mechanical System
[Relazione in Atti di Convegno]
Secchi, Cristian; Fantuzzi, Cesare
abstract
In this paper we address the problem of the control over networks of mechanical systems. We exploit the scattering framework to extend the energy shaping methodology in case the controller and the plant are interconnected through a delayed network. Furthermore, we exploit a result recently proposed for passivity based telemanipulation for guaranteeing the asymptotic stabilization of the desired configuration also in case of loss of information during the communication as it can very likely happen when using Ethernet-like networks (e.g. Internet).
2007
- Kinematic Compensation in Port-Hamiltonian Telemanipulation
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S; Fantuzzi, Cesare
abstract
One of the main drawbacks of passivity based bilateral telemanipulationover delayed communication channels is the presence of a position drift betweenmaster and slave robots during contact tasks; this kinematic mismatch degradesthe interaction feeling perceived by the user. In this paper we consider port-Hamiltonian based telemanipulators and we exploit the interconnection structureof port-Hamiltonian systems to passively compensate the position drift.
2007
- Modelli orientati agli oggetti per sistemi con dinamiche ibride
[Articolo su rivista]
M., Bonfé; Fantuzzi, Cesare; Secchi, Cristian; S., Simani
abstract
Nel presente articolo viene presentata una metodologia per la modellazione el' analisi di processi industriali, il cui scopo e quello di unificare tutti gli aspetti concettuali coinvolti nello sviluppo delle logiche di controllo. In particolare, I'approccio proposto integra i concetti delle tecniche di modellazione orientate agli oggetti, ampiamente note agli sviluppatori software, con i concetti fondamentali dei Bond Graph, un linguaggio di modellazione per sistemi fisici di natura eterogenea basato sulle interazioni energetiche fra componenti basilari.L' articolo mostra inoltre come i modelli ottenuti con il metodo presentato possano essere analizzati con metodiformali per la verifica di sistemi ibridi, cioe sistemi nei quali dinamiche tempo-continue interagiscono condinamiche discrete e regole logiche.
2007
- Object-Oriented Modeling of Complex Mechatronic Components for the Manufacturing Industry
[Articolo su rivista]
Secchi, Cristian; M., Bonfé; Fantuzzi, Cesare; R., Borsari; D., Borghi
abstract
The advantages of object-oriented modeling, as modularity and reusability of components, are very important also for modeling manufacturing systems and not only for software development. Recently, a unified object-oriented approach for modeling both the logical and the physical part of a manufacturing machine has been proposed. In this paper we show the effectiveness of this new modeling framework on an industrial application. The case study consists of the package forming unit of a filling machine for liquid food packaging, developed by Tetra Pak Carton Ambient S.p.a.
2007
- On the use of UML for modeling mechatronic systems
[Articolo su rivista]
Secchi, Cristian; Bonfe, M; Fantuzzi, Cesare
abstract
This paper describes a modeling language that aims to provide a unified framework for representing control systems, namely, physical plants coupled with computer-based control devices. The proposed modeling methodology is based on the cardinal principle of object orientation, which allows describing both control software and physical components using the same basic concepts, particularly those of capsules, ports, and protocols. Furthermore, it is illustrated how the well-known object-oriented specification language unified modeling language can be adopted, provided an adequate formalization of its semantics, to describe structural and behavioral aspects of control systems, related to both logical and physical parts. Note to Practitioners-The development of an automated system within an industrial setting is a complex task, whose successful result depends on the joint efforts of a team of designers with different scientific backgrounds and specialized knowledge. In fact, an automated system is typically composed of a mechanical assembly, which must be precisely designed and manufactured, and a set of sensors and actuators (e.g., electrical drives, pneumatic systems, etc.), which are, on their turn, controlled most of the time by means of digital processors. course, both electrical parts and control algorithms (e.g., proportional integral, and derivative (PID) regulators, logic and supervisory control, reference trajectories for mechanical motions, etc.) should be designed with the same care given to mechanical aspects. Moreover, it is undeniable that none of the various parts composing the automated system design specification can, on their own, allow engineers to understand the actual behavior of the whole system, especially without a common description language that is understandable for all of the designers. The present paper introduces a unified language which aims to support integrated design specifications of automated systems, including the dynamics of heterogeneous physical assemblies, the discrete-event behavior of distributed control software, and the specification of interface ports between the plant and the control system. With the proposed language, it is possible to obtain a complete picture of the automated system suitable for its simulation, documentation, and validation. The modeling language described in the paper supports the principles of object orientation. This choice moves in the direction of enhancing modularity and reusability properties of design specifications, which are aspects of great importance in the design practice. Moreover, the object-oriented approach to automated systems design proposed in the paper aims to introduce the concept of design by extension in the manufacturing industry. This means that the definition of specialization relationships between classes of components implies that those components should be designed in order to be substitutable with each other, especially from a dynamic point of view. This aspect will be the subject of further papers illustrating other practical insights on the use of object-oriented models for automated systems.
2007
- Physical modeling and port-Hamiltonian systems
[Capitolo/Saggio]
Secchi, C.; Fantuzzi, C.; Stramigioli, S.
abstract
Interaction between physical systems is determined by an exchange of energy and, therefore, a first step towards the control of interaction is to explicitly model the energetic properties of physical systems. © 2007 Springer-Verlag Berlin Heidelberg.
2007
- Port-Hamiltonian based bilateral telemanipulation
[Capitolo/Saggio]
Secchi, C.; Fantuzzi, C.; Stramigioli, S.
abstract
Telemanipulation is one of the first fields of application of robotics (see [326] for an early history) and still one of the most challenging. In teleoperation a human operator has to perform a certain task on a remote environment. The human operator commands a local robotic interface (called master). The motion of the master is transmitted through a communication channel to a remote robot (called slave) which should replicate the motion of the master and perform a desired task on the remote environment. It is possible to improve performances providing to the human operator some real-time information about the interaction of the slave with the remote environment. This feedback information can be achieved in several ways (e.g. through visual displays, [146]) but the best way to improve the operator's ability is to feedback the contact force between the slave and the environment to the master side. When the force at the slave side is reflected back to the human operator, it is said that the telemanipulation is controlled bilaterally, or, more simply, that we have a bilateral telemanipulation system. When teleoperation is performed over a great distance, such as in undersea or in space applications, or over packet switching network, such as the Internet, the communication delay associated to the transmission of information from master side to slave side and vice-versa becomes non negligible and it can therefore destabilize the whole system. © 2007 Springer-Verlag Berlin Heidelberg.
2007
- Port-contact systems in bilateral telemanipulation
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S; Fantuzzi, Cesare
abstract
In this paper we develop one of the first control applications of therecently proposed port-contact framework. We show how it is possible to modeland control a bilateral telemanipulation system using port-contact systems andwe develop a port-contact impedance controller that allows to impose a desiredinteractive behavior and a zero steady state position error during contact tasks.
2007
- Power scaling in port-Hamiltonian telemanipulation over packet switched networks
[Capitolo/Saggio]
Secchi, Cristian; S., Stramigioli; Fantuzzi, Cesare
abstract
The aim of this contribution is to provide a communication strategythat allows power scaling over a packet switched communication channel in a digital port-Hamiltonian based telemanipulation scheme. We will firstly prove that in case of negligible communication delay, power scaling can beachieved without compromising the stable behavior of the telemanipulationscheme. Secondly, we will propose a novel scattering based communicationstrategy that allows to scale the power exchanged also in case of non negligiblecommunication delay. Finally we will consider the problem of loss of packetsin the communication; we will show that if lost packets are not properly handledthe system can become unstable and then we will propose a strategy thatpreserves the stable behavior of the overall scheme independently of the lossof packets.
2007
- Transparency in port-Hamiltonian based telemanipulation
[Capitolo/Saggio]
Secchi, C.; Fantuzzi, C.; Stramigioli, S.
abstract
Stability is a key issue in the implementation of a bilateral telemanipulation system since both the non-negligible time delay in the communication between master and slave and the interaction with unknown environments can destabilize the whole system. In Chap. 4 it has been shown that passivity theory and port-Hamiltonian systems can be fruitfully used to build an intrinsically passive telemanipulation scheme which, therefore, has a stable behavior both in case of free motion and in case of contact with any passive, possibly unknown, environment. Scattering theory has been used to build a communication channel which is lossless independently of any constant transmission delay and the problem of wave reflection arising when coupling master and slave side through scattering based communication channels has been solved. The scheme has been extended in order to take into account the sampled data nature of controllers in a passive way. Moreover discrete scattering has been defined and packet-switching transmission lines have been considered. A communication strategy that allows to preserve passivity even in case of loss of packets and of variable transmission delay has been proposed. Finally, a passivity preserving algorithm that allows to rebuild lost packets by interpolation has been proposed. © 2007 Springer-Verlag Berlin Heidelberg.
2006
- A Distributed Embedded Control System for Agricultural Machines
[Relazione in Atti di Convegno]
Fantuzzi, Cesare; Ruggeri, M.; Marzani, S; Secchi, Cristian
abstract
This paper concerns the description of a distributed embedded control system for agricultural machines, as tractors and off-road vehicles. The distributed control system is based on the international standard ISO 11783, also known as ISOBUS standard. The paper describes the safety and system integrity analysis of a hybrid network for off-highway vehicles where ISOBUS and FlexRay protocols co-exist.
2006
- A coalgebraic approach to behavioral inheritance in Dynamical Systems
[Relazione in Atti di Convegno]
Secchi, Cristian; Bonfe', M; Fantuzzi, Cesare
abstract
The paper introduces a formal definitionof inheritance, which is a cardinal concept inobject-oriented software, for dynamical systems. Theproposed definition exploits the coalgebraic descriptionof software artifacts to provide a connection betweenthe behavioral approach for modeling dynamicalsystems and the object-oriented approach for softwaremodeling and design
2006
- An object-oriented approach to manufacturing systems modeling
[Relazione in Atti di Convegno]
Bassi, L; Fantuzzi, Cesare; Bonfe', M; Secchi, Cristian
abstract
This paper describes a methodology to support the design process of complex systems. The main challenge in modern industrial applications is the sheer volume of data involved in the design process. While using high-level abstraction is necessary to manage this data and analyze the system "as a whole", designers need also to retain all the low-level information of the system, in order to be able to perform optimizations and modifications at later times. The solution proposed here is to use a hierarchy of models that describe the system at different levels of abstraction, and are arranged in such a way that is possible to easily "map" each level onto the others. The topmost layer of the system description is expressed in System Modeling Language (SysML), a general-purpose modeling language based on UMLreg
2006
- Behavioural inheritance in object-oriented models for mechatronic systems
[Articolo su rivista]
M., Bonfé; Secchi, Cristian; Fantuzzi, Cesare
abstract
Abstract: This paper describes a formal framework for Object-Oriented (O-O) modelling of mechatronic systems, whose main contribution is, on the one hand, to unify the modelling approaches for dynamical systems and for industrial control software and, on the other hand, to provide a definition of inheritance, a cardinal concept in object-orientation, which emphasises the behavioural conformity of basic and derived classes of objects. The proposed framework exploits the coalgebraic description of software artefacts to provide a connection between the behavioural approach for modelling dynamical systems and the O-O approach for software modelling and design. In particular, our definition of inheritance aims to allow control engineers to apply the design by extension methodology, widely used in software engineering, to the development of mechatronic components for manufacturing systems.
2006
- Design by Extension and Inheritance of behavior in Dynamical Systems
[Relazione in Atti di Convegno]
Secchi, Cristian; Bonfe', M; Fantuzzi, Cesare
abstract
The paper introduces a formal definition of inheritance, which is a cardinal concept in object-oriented software, for dynamical systems. The proposed definition exploits the coalgebraic description of software artifacts to provide a connection between the behavioral approach for modeling dynamical systems and the object-oriented approach for software modeling and design. This definition allows to apply the design by extension methodology, widely used in software engineering, to the design of components of manufacturing systems
2006
- Inheritance for Dynamical Systems
[Relazione in Atti di Convegno]
Secchi, Cristian; Fantuzzi, Cesare
abstract
Object-orientation is a very effective approach formodeling complex manufacturing systems. In this paper we introducea formal definition of behavioral inheritance for dynamicalsystems based on the recently proposed coalgebraic descriptionof object-oriented software. This definition allows to extendthe design by extension methodology, widely used in softwareengineering, to the design of components of manufacturingsystems.
2006
- Intrinsically Passive Force Scaling in Haptic Interfaces
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S; Fantuzzi, Cesare
abstract
In several applications involving haptic interfaces it can be desirable to scale the interaction force perceived by the user. The most intuitive approach is to change the stiffness of the virtual environment but, unfortunately, changing the physical parameters that characterize a virtual environment is a potentially destabilizing action. In this paper we embed in the intrinsically passive haptic scheme recently proposed in S. Stramigioli et al. (2005) a power scaling interconnection that allows to scale the force perceived by the user while preserving the passivity, and consequently the stable behavior, of the overall system
2006
- Position drift compensation in port-Hamiltonian based telemanipulation
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S; Fantuzzi, Cesare
abstract
Passivity based bilateral telemanipulation schemes are often subject to a position drift between master and slave if the communication channel is implemented using scattering variables. The magnitude of this position mismatch can be significant during interaction tasks. In this paper we propose a passivity preserving scheme for compensating the position drift arising during contact tasks in port-Hamiltonian based telemanipulation improving the kinematic perception of the remote environment felt by the human operator
2006
- Towards Object-Oriented Modeling of Complex Mechatronic Systems for the Manufacturing Industry
[Relazione in Atti di Convegno]
Zanichelli, D; Secchi, Cristian; Rubini, Riccardo; Fantuzzi, Cesare; Bonfe', M; Borghi, D; Borsari, R; Sacchetti, E.
abstract
The advantages of object-oriented modeling, as modularity and reusability of components, are very important also for modeling manufacturing systems and not only for software development. In [1] a unified object-oriented approach for modeling both the logical and the physical part of a manufacturing machine has been proposed. In this paper we report an industrial application of this modeling strategy and the case study consists of the package forming unit of a filling machine for liquid food packaging, developed by Tetra Pak Carton Ambient S.p.a.
2006
- Variable delay in scaled port-Hamiltonian telemanipulation
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S; Fantuzzi, Cesare
abstract
In several applications involving bilateral telemanipulation, master andslave act at different power scales. In this paper a strategy for passively dealing withvariable communication delay in scaled port-Hamiltonian based telemanipulationover packet switched networks is proposed.
2005
- Inheritance of Behavior in Object-Oriented Designs for industrial control systems
[Relazione in Atti di Convegno]
Bonfe', M.; Fantuzzi, Cesare; Secchi, Cristian
abstract
The paper presents a feasible approach to introduce object-orientedtechniques in the industrial practice of control design. The approach is based onthe use of a domain-specific extension of the modeling language UML and on theformalization of design models as transition systems for verification purposes. Inparticular, the paper shows how to exploit model checking techniques to verifythat object classes, designed as subtypes, correctly inherit the behavior of theirbase classes, according to a notion of substitutability specifically defined for theproposed semantics of object-oriented models.
2005
- Object-oriented modeling of multi-domain systems
[Relazione in Atti di Convegno]
M., Bonfe'; Fantuzzi, Cesare; Secchi, Cristian
abstract
The paper describes a modeling language that aims to provide a unified framework for multi-domain physical systems coupled with computer-based control devices. The proposed modeling methodology is based on the cardinal principle of object orientation, which allows to describe both control software and physical components using the same basic concepts, particularly those of classes and interface ports.
2005
- On the use of UML for modeling physical system
[Relazione in Atti di Convegno]
Secchi, Cristian; Fantuzzi, Cesare; Bonfe', M.
abstract
The aim of this paper is to provide a unified language for modeling both control software and physical plants in real time control systems. This is done by embedding the bond graph modeling language for physical systems into the UML-RT framework, widely used to model distributed real-time software
2005
- Power Scaling in port-Hamiltonian based Telemanipulation
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S.; Fantuzzi, Cesare
abstract
In several applications involving bilateral telemanipulation, master and slave robots act at different power scales (e.g. telesurgery). The aim of this paper is to embed power scaling into port-Hamiltonian based bilateral telemanipulation schemes, In order to deal with nonnegligible transmission delays we propose a novel scattering based communication strategy to properly scale the power exchanged by master and slave while preserving a stable behavior of the overall scheme.
2005
- Sampled data systems passivity and discrete port-Hamiltonian systems
[Articolo su rivista]
S., Stramigioli; Secchi, Cristian; AJ Van der, Schaft; Fantuzzi, Cesare
abstract
In this paper, we present a novel way to approach the interconnection of a continuous and a discrete time physical system first presented in [1]-[3]. This is done in a way which preserves passivity of the coupled system independently of the sampling time T. This strategy can be used both in the field of telemanipulation, for the implementation of a passive master/slave system on a digital transmission line with varying time delays and possible loss of packets (e.g., the Internet), and in the field of haptics, where the virtual environment should 'feel' like a physical equivalent system.
2005
- The problem of packets loss in scaled digital port-Hamiltonian based bilateral telemanipulation
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S.; Fantuzzi, Cesare
abstract
The goal of this paper is to embed power scaling into port-Hamiltonian based telemanipulation schemes over packet switched networks. We propose a discrete scattering based communication strategy and a way to handle lost packets that allow power scaling while preserving a stable behavior of the system independently of any communication delay and of any possible loss of packets
2005
- Transparency in port-Hamiltonian based Telemanipulation
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S.; Fantuzzi, Cesare
abstract
After stability, transparency is the major issue in the design of a telemanipulation system. In this paper we exploit a behavioral approach in order to provide an index for the evaluation of transparency in port-Hamiltonian based teleoperators. Furthermore we provide a transparency analysis of packet switching scattering based communication channels.
2005
- UML come linguaggio di modellazione unificato per sistemi meccatronici
[Relazione in Atti di Convegno]
Bonfe', M.; Fantuzzi, Cesare; Secchi, Cristian
abstract
Nel presente articolo, viene proposto un linguaggio di modellazione il cui scopo è quello di fornire una lingua franca per tutti i progettisti coinvolti nello sviluppo di un sistema meccatronico. Al fine di raggiungere tale obiettivo, il linguaggio presentato unifica i concetti fondamentali dell’approccio orientato agli oggetti (Object-Oriented, O-O), tipico dei sistemi software rappresentati con modelli UML, ed i concetti fondamentali dei Bond Graphs, un linguaggio di modellazione per sistemi fisici di natura eterogenea basato sulle interazioni energetiche fra componenti basilari.L’articolo mostra come i concetti propri dei Bond Graphs ed, in particolare, della loro formalizzazione in termini di sistemi Port-Hamiltonian, possano essere incorporati nel linguaggio UML, adottandone il profilo definito originariamente per sistemi software distribuiti e Real-Time. In tal modo, sia le specifiche strutturali e di comportamento del software di controllo che le dinamiche continue del sistema fisico possono essere descritte in un unico modello, facilitando così la progettazione integrata dei sistemi meccatronici.
2005
- Unified Modeling and Verification of Logic Controllers for Physical Systems
[Relazione in Atti di Convegno]
Bonfe', M.; Fantuzzi, Cesare; Secchi, Cristian
abstract
The paper describes a modeling approach that aims to provide a unified framework for the specification and verification of logic controllers for multi-domain physical systems. The proposed modeling methodology is based on the cardinal principle of object orientation, which allows to describe both control software and physical components using the same basic concepts, like classes and interface ports, and the same modeling notation, based on the UML language. Thanks to this unified approach, it is possible to describe structural and behavioral aspects of any multi-domain system coupled with a logic control device. Moreover, the behavior of the closed-loop system can be analyzed with formal verification techniques for hybrid systems, in order to prove correctness properties otherwise difficult to verify considering only discrete-event models.
2005
- Unified modeling of control software and physical plants
[Relazione in Atti di Convegno]
Secchi, Cristian; Fantuzzi, Cesare; Bonfe', M.
abstract
The aim of this paper is to provide a unified language for modeling bothcontrol software and physical plants in real time control systems. This is done byembedding the bond graph modeling language for physical systems into the UMLRTframework, widely used to model distributed real-time software.
2005
- Verification of Behavioral Substitutability in Object-oriented Models for Industrial Controllers
[Relazione in Atti di Convegno]
Bonfe', M.; Fantuzzi, Cesare; Secchi, Cristian
abstract
The aim of the paper is to provide a practical method to introduce design principles typical of the object-oriented approach, like “design by extension”, to the application domain of manufacturing systems control design. The proposed method is based on a domain-specific extension of the modeling language UML and on the formalization of design models as transition systems for verification purposes. Object-oriented models, formalized according to the proposed semantics, can be analyzed with model checking techniques in order to verify the behavioral conformity of object classes, according to a notion of substitutability which is defined in the paper specifically for the proposed modeling language.
2004
- Energetic Approach to Parametric Fault detection and Isolation
[Relazione in Atti di Convegno]
Fantuzzi, Cesare; Secchi, Cristian
abstract
This paper concerned with the diagnosis and identification of parametric fault which may occur in a physical system. The method uses a bond graph system model to generate residual signals for fault diagnosis. Fault identification of system parameters is obtained by the analysis of the bond graph model topology.
2003
- A Variable Structure Approach to Energy Shaping
[Relazione in Atti di Convegno]
Macchelli, A.; Melchiorri, C.; Secchi, Cristian; Fantuzzi, Cesare
abstract
The port-Hamiltonian formalism is a very powerful tool for describingdynamical systems and their interconnections and fordesigning control laws with specified energetic properties. Inthis paper, in particular, it is shown how a variable structurecontrol can be designed in this general framework in order toachieve a passive systems with, additionally, the robust propertiesobtainable with variable structure systems. Simulationresults obtained with a 2-dof manipulator are reported and discussedin order to validate the proposed approach.
2003
- Control of an Industrial Robot Using RTAI Linux
[Relazione in Atti di Convegno]
Secchi, Cristian; Fantuzzi, Cesare; Gianotti, A.
abstract
In this paper we present the real-time control of an industrial manipulator with RTAI-Linux whichhas been developed at the Mechatronics laboratory of the University of Modena and Reggio Emilia. Therobot is an AXTRON and it is produced by the RRRobotica in Reggio Emilia (Italy). The manipulatoris a SCARA-like robot with three degrees of freedom; it has two actuated rotational joints and a manualprismatic joint. The robot is mainly used for micro percussion marking, engraving and glue dispensing.Each rotational joint is actuated by a stepper motor with a resolution of 0.024 mm and the actuated axesare provided with range-delimiters.
2003
- Dealing with Unreliabilities in Digital Passive Geometric Telemanipulation
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S.; Fantuzzi, Cesare
abstract
In this paper two problems arising in the digital passive scheme for telemanipulation presented in are addressed. At first, we show how to preserve system passivity in presence of quantization error introduced by position sensor (i.e. encoders) by introducing energy dissipation. Then, we introduce a scheme for a redundant communication channel that will compensate for missed packets improving performances while preserving passivity of the overall scheme.
2003
- Delayed Virtual Environments: a port-Hamiltonian Approach
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S.; Fantuzzi, Cesare
abstract
In this paper the problem of delayed virtual environments in haptics is addressed. We show that the approach outlined is no longer passive in case of (computational) delay on the output of the virtual environment. Passivity can be recovered using scattering theory; a discretization algorithm which leads to a discrete passive port-Hamiltonian systems with respect to any delay on the output is proposed.
2003
- Digital passive geometric telemanipulation
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S.; Fantuzzi, Cesare
abstract
In this paper we present an intrinsically passive telemanipulation scheme over a digital transmission line Internet-like. We present an analysis of the energetic behavior of the communication line both in case of loss of packages and in case of variable delay. The sample data nature of the passive controller is explicitly taken into account following the approach outlined
2003
- On the Fault Detection and Isolation of Industrial Robot Manipulators
[Relazione in Atti di Convegno]
Fantuzzi, Cesare; Secchi, Cristian; Visioli, A.
abstract
Fault detection and isolation of robot manipulators is a subject that has beenwidely investigated in the past decade and different methodologies have been proposed.However, there is still a lack of techniques that are adequate to a straightforwardapplication to the detection of real fault in industrial robots. In this paper we proposea very simple but effective strategy for fault detection and isolation, which is based onthe analysis of the robot behavior matching with real mechanical and electrical failures.Simulation results show the effectiveness of the method, despite its straightforwardnesscompared to the approaches proposed by recent literature.
2002
- A Novel Theory for Sample Data Systems
[Relazione in Atti di Convegno]
Stramigioli, S.; Secchi, Cristian; VAN DER SCHAFT, A. J.; Fantuzzi, Cesare
abstract
This paper presents a novel approach to the interconnection of a continuous time and a discrete time physical system. This is done in a way which preserves the passivity of the coupled system independently of the sampling time. A direct application in the field of haptic displays, where a virtual environment should feel like equivalent physical systems, is presented.
2001
- Geometric Grasping and Telemanipulation
[Relazione in Atti di Convegno]
Secchi, Cristian; Stramigioli, S.; Melchiorri, C.
abstract
In this paper, an extension of the so-called intrinsic passive control (IPC) is illustrated, showing that an improvement of performances can be achieved by considering different types of energy-storing elements, i.e. "springs", in the IPC. In particular, two new "springs" are introduced: a 'variable rest length' spring and a 'variable stiffness' spring, that are properly defined in order to maintain the passivity of the IPC and to improve its performances in given situations. Simulations of the resulting control, applied to a defective system and to a simple telemanipulation device, are presented and discussed