Nuova ricerca


Ricercatore t.d. art. 24 c. 3 lett. B presso: Dipartimento di Scienze e Metodi dell'Ingegneria

Home | Curriculum(pdf) | Didattica |


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.

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

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.

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 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

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 - 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

2020 - Human-Friendly Robotics 2019. HFR 2019. [Monografia/Trattato scientifico]
Ferraguti, F.; Villani, V.; Sabattini, L.; Bonfè, M.

2020 - Human-robot coexistence and interaction in open industrial cells [Articolo su rivista]
Magrini, E.; Ferraguti, F.; Ronga, A. J.; Pini, F.; De Luca, A.; Leali, F.

Recent research results on human–robot interaction and collaborative robotics are leaving behind the traditional paradigm of robots living in a separated space inside safety cages, allowing humans and robot to work together for completing an increasing number of complex industrial tasks. In this context, safety of the human operator is a main concern. In this paper, we present a framework for ensuring human safety in a robotic cell that allows human–robot coexistence and dependable interaction. The framework is based on a layered control architecture that exploits an effective algorithm for online monitoring of relative human–robot distance using depth sensors. This method allows to modify in real time the robot behavior depending on the user position, without limiting the operative robot workspace in a too conservative way. In order to guarantee redundancy and diversity at the safety level, additional certified laser scanners monitor human–robot proximity in the cell and safe communication protocols and logical units are used for the smooth integration with an industrial software for safe low-level robot control. The implemented concept includes a smart human-machine interface to support in-process collaborative activities and for a contactless interaction with gesture recognition of operator commands. Coexistence and interaction are illustrated and tested in an industrial cell, in which a robot moves a tool that measures the quality of a polished metallic part while the operator performs a close evaluation of the same workpiece.

2020 - Optimized power modulation in wave based bilateral teleoperation [Articolo su rivista]
Ferraguti, Federica; Bonfe, Marcello; Fantuzzi, Cesare; Secchi, Cristian

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

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

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.

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

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

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 - 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.

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 - Augmented reality based approach for on-line quality assessment of polished surfaces [Articolo su rivista]
Ferraguti, Federica; Pini, Fabio; Gale, Thomas; Messmer, Franck; Storchi, Chiara; Leali, Francesco; Fantuzzi, Cesare

Augmented reality is considered one of the enabling technologies of the fourth industrial revolution, within the Industry 4.0 program and beyond. Indeed, augmented reality solutions can increase the working quality and the productivity and allow a better use of the human resources. This technology can help the operator in the industrial applications during the crucial phases of the processes. Since the quality assessment of the surfaces is recognized to be a key phase in the polishing process, in this paper we propose a novel method that exploits augmented reality to support the operators during this phase. The metrology data measured by a surface measurement system are directly projected on the polished component through an augmented reality headset worn by the operators and used to assess the quality of the worked surfaces. Rather than imagine how a certain parameter change can affect the result achieved, the information is directly there on the component's surface. Users can see from the data where refinements are required and make better and faster decisions, which is compelling for its potential beyond industrial polishing. The proposed method is implemented and validated on an industrial cell, where the robot automatically perform the polishing task and move the head of the surface measurement system along the surface to measure the metrology parameters. Thanks to the proposed approach, the end-user and the operator can directly see on the component if the quality reached satisfies the specifications or if some parts of the surface require further refinements through additional polishing steps.

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

2019 - Energy optimization for a robust and flexible interaction control [Relazione in Atti di Convegno]
Secchi, C.; Ferraguti, F.

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 - 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

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.

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 - Safety-oriented robot payload identification using collision-free path planning and decoupling motions [Articolo su rivista]
Farsoni, Saverio; Ferraguti, Federica; Bonfè, Marcello

The paper presents a procedure for the identification of the inertial parameters of the payload mounted on the end-effector of a robotic manipulator operating in a collaborative setup. The procedure is therefore designed considering as a primary objective the safe execution of the payload estimation process, in terms of avoidance of physical objects and protected zones within the robot workspace, in which the presence of human operators is allowed and expected. The methods applied in the definition of the proposed operational sequence include a collision-free path planner and a joint trajectory generator that allows the safe execution of specific test motions. In particular, each one of such test motions decouples the effects of all but one inertial parameter of the payload, in order to improve the accuracy of identification. Experimental results on a redundant industrial manipulator demonstrate the feasibility of the proposed identification method.

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

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 - 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

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

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.

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

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 - 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

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 - 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

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

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

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 - Catching the wave: A transparency oriented wave based teleoperation architecture [Relazione in Atti di Convegno]
Secchi, Cristian; Ferraguti, Federica; Fantuzzi, Cesare

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 - Metodo per il trattamento superficiale di un manufatto [Brevetto]
Fantuzzi, Cesare; Secchi, Cristian; Ferraguti, Federica; Talignani Landi, Chiara; Noli, Marco

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 - Optimizing the use of power in wave based bilateral teleoperation [Relazione in Atti di Convegno]
Ferraguti, Federica; Fantuzzi, Cesare; Secchi, Cristian

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 - 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

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

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 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

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 - 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

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

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

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 - 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

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.

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.

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 - Planning and Simulation of Percutaneous Cryoablation [Relazione in Atti di Convegno]
Dodi, Riccardo; Ferraguti, Federica; Ristolainen, Asko; Secchi, Cristian; Sanna, Alberto

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.

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

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 Tank-Based Approach to Impedance Control with Variable Stiffness [Relazione in Atti di Convegno]
Ferraguti, Federica; Secchi, Cristian; Fantuzzi, Cesare

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 - 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

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.