@article {1756, title = {Mechanism of Motor reduction with variable rigidity and rapidly controllable}, year = {2010}, address = {USA}, keywords = {Robotics}, issn = {US7699731}, author = {A. Bicchi and G. Tonietti} } @conference {MED08-HTB, title = {Neural network based robust adaptive control for a variable stiffness actuator}, booktitle = {Control and Automation, 16 th Mediterranean Conference on Control and Automation}, year = {2008}, pages = {1028 - 1034}, abstract = {

In this paper we present a robust adaptive controller based on a neural network (NN) for a variable stiffness actuator (VSA). The controller is able to independently set the mechanical stiffness and position at the joint shaft to guarantee robustness with respect to slowly time-varying and unmodeled friction coefficients affecting the dynamics of the actuator. The lumped uncertainties of the VSA including unmodeled dynamics are considered and approximated by a simple NN so that the controlled system is asymptotically stable, and remains effective while process conditions vary. To cope with the reconstruction error of the NN, a sliding mode like additional robust control term is introduced. The proofs for the uniformly ultimately bounded (UUB) and uniform asymptotic (UAS) stabilities for the closed-loop system are provided in detail via Lyapunov theory. Simulation and experimental results are reported in support of both validity and performance of the proposed approach.

}, keywords = {Embedded Control, Robotics}, author = {S. Huh and G. Tonietti and A. Bicchi} } @conference {AMC08, title = {Physical Human-Robot Interaction: Dependability, Safety, and Performance}, booktitle = {Proc. 10th Intl. Workshop Advanced Motion Control}, year = {2008}, pages = {9-14}, abstract = {

In this paper we discuss the problem of achieving good performance in accuracy and promptness by a robot manipulator under the condition that safety is guaranteed throughout task execution. Intuitively, while a rigid and powerful structure of the arm would favor its performance, lightweight compliant structures are more suitable for safe operation. The quantitative analysis of the resulting design trade-off between safety and performance has a strong impact on how robot mechanisms and controllers should be designed for human-interactive applications. We discuss few different possible concepts for safely actuating joints, and focus on aspects related to the implementation of the mechanics and control of this new class of robots.

}, keywords = {Embedded Control, Physical Human-Robot Interaction (pHRI), Robotics}, author = {A. Bicchi and M. Bavaro and G. Boccadamo and D. De Carli and R. Filippini and G. Grioli and M. Piccigallo and A. Rosi and R. Schiavi and S. Sen and G. Tonietti} } @conference {filippini2007cda, title = {A Comparative Dependability Analysis of Antagonistic Actuation Arrangements for Enhanced Robotic Safety}, booktitle = {Proc. IEEE Int. Conf. on Robotics and Automation}, year = {2007}, pages = {4349{\textendash}4354}, abstract = {In this paper we introduce an analysis of dependability of an elementary yet critical component of robotic systems designed to operate in environments shared with humans, i.e. the joint-level actuation system. We consider robot joints that implement the Variable Impedance Actuation (VIA) paradigm. The VIA has been demonstrated to be an effective mean to achieve high performance while constantly keeping injury risks to humans by accidental impacts below a given threshold. The paper describe possible implementations of the VIA concept which use the Antagonistic Actuation (AA) in three different arrangements. This study follows a previously reported paper dealing with safety. Here a detailed comparative dependability and performability analysis in front of possible specific failure modes is conducted, whose results provide additional and useful guidelines for design of safe and dependable actuation systems for physical human-robot interaction. }, keywords = {Robotics}, author = {R. Filippini and S. Sen and G. Tonietti and A. Bicchi} } @conference {SSTB-WH07, title = {Integrating Two Haptic devices for Performance Enhancement}, booktitle = {World Haptics Conference 2007}, year = {2007}, pages = {139-144}, abstract = {

This paper deals with a new configuration for a haptic system, which is able to simultaneously replicate independent force/displacement and force/area behaviors of a given material. Being force/area information a relevant additional haptic cue for improving softness discrimination, this system allows to extend the range of materials whose rheology can be carefully mimicked. Moreover, according to the Hertz theory, two objects with different curvature radius having the same force/displacement behavior can respond with different contact area to the same applied force. These behaviors can be effectively replicated by the integrated haptic system here proposed enabling and independent control of force/displacement and force/area. The system is comprised of a commercial device (Delta Haptic Device) serially coupled with a Contact Area Spread Rate (CASR) device. Two specimens of a material and two of another one, all with different curvature radii, were identified and modeled in terms of force/area and force/displacement. These behaviors were successfully tracked by the integrated haptic system here proposed.

}, keywords = {Haptics}, author = {E. P. Scilingo and N. Sgambelluri and G. Tonietti and A. Bicchi} } @inbook {ISER04, title = {Optimal Mechanical/Control Design for Safe and Fast Robotics}, booktitle = {Experimental Robotics IX: The 9th International Symposium on Experimental Robotics}, series = {Springer Tracts in Advanced Robotics}, volume = {21}, year = {2006}, pages = {311 - 320}, publisher = {Springer Berlin / Heidelberg}, organization = {Springer Berlin / Heidelberg}, abstract = {

The problem to ensure safety of performant robot arms during task execution was previously investigated by authors. The problem can be approached by studying an optimal control policy, the "Safe Brachistocrone", whose solutions are joint impedance trajectories coordinated with desired joint velocities. Transmission stiffness is chosen so as to achieve minimum-time task execution for the robot, while guaranteeing an intrinsic safety level in case of an unexpected collision between a link of the arm and a human operator. In this paper we extend this approach to more general classes of robot actuation systems, whereby other impedance parameters beside stiffness (such as e.g. joint damping and/or plasticity) can vary. We report on a rather extensive experimental campaign validating the proposed approach.

}, keywords = {Physical Human-Robot Interaction (pHRI), Robotics}, author = {G. Tonietti and R. Schiavi and A. Bicchi}, editor = {Marcelo H. Ang, Oussama Khatib} } @inbook {BSSTB06, title = {Optimization and Fail-Safety Analysis of Antagonistic Actuation for pHRI}, booktitle = {European Robotics Symposium 2006}, series = {Springer Tracts in Advanced Robotics}, volume = {22}, year = {2006}, pages = {109 - 118}, publisher = {Springer Berlin / Heidelberg}, organization = {Springer Berlin / Heidelberg}, abstract = {

In this paper we consider some questions in the design of actuators for physical Human-Robot Interaction (pHRI) under strict safety requirements in all circumstances, including unexpected impacts and HW/SW failures. We present the design and optimization of agonistic-antagonistic actuation systems realizing the concept of variable impedance actuation (VIA). With respect to previous results in the literature, in this paper we consider a realistic physical model of antagonistic systems, and include the analysis of the effects of cross-coupling between actuators. We show that antagonistic systems compare well with other possible approaches in terms of the achievable performance while guaranteeing limited risks of impacts. Antagonistic actuation systems however are more complex in both hardware and software than other schemes. Issues are therefore raised, as to fault tolerance and fail safety of different actuation schemes. In this paper, we analyze these issues and show that the antagonistic implementation of the VIA concept fares very well under these regards also.

}, keywords = {Physical Human-Robot Interaction (pHRI), Robotics}, author = {G. Boccadamo and R. Schiavi and S. Sen and G. Tonietti and A. Bicchi}, editor = {H. Christensen} } @conference {PHRI06, title = {Safe and Dependable Physical Human-Robot Interaction in Anthropic Domains: State of the Art and Challenges}, booktitle = {Proc. IROS{\textquoteright}06 Workshop on pHRI - Physical Human-Robot Interaction in Anthropic Domains}, year = {2006}, publisher = {IEEE}, organization = {IEEE}, keywords = {Robotics}, author = {R. Alami and A Albu-Schaeffer and A. Bicchi and R. Bischoff and R. Chatila and A. De Luca and De Santis, A and G. Giralt and J. Guiochet and G. Hirzinger and F. Ingrand and V. Lippiello and R. Mattone and D. Powell and S. Sen and B. Siciliano and G. Tonietti and L. Villani}, editor = {A. Bicchi and A. De Luca} } @conference {TSB05, title = {Design and Control of a Variable Stiffness Actuator for Safe and Fast Physical Human/Robot Interaction}, booktitle = {Proc. IEEE Int. Conf. on Robotics and Automation}, year = {2005}, pages = {528-533}, abstract = {

This paper is concerned with the design and control of actuators for machines and robots physically interacting with humans. According to criteria established in our previous work on mechanical-control co-design for intrinsically safe, yet performant machines, we pursue the Variable Impedance Actuation (VIA) approach, purporting actuators that can control in real-time both the reference position and the mechanical impedance of the moving parts in the machine. In this paper we describe an implementation of such concepts, consisting of a novel electromechanical Variable Stiffness Actuation (VSA) motor. The design and the functioning principle of the VSA are reported, along with the analysis of its dynamic behavior. A novel scheme for feedback control of this device is presented, along with experimental results showing performance and safety of a one-link arm actuated by the VSA motor.

}, keywords = {Robotics}, author = {G. Tonietti and R. Schiavi and A. Bicchi} } @conference {BBCCCCPT05, title = {From tele-laboratory to e-learning in automation curricula at the university of Pisa}, booktitle = {Proc. IFAC World Congress}, year = {2005}, abstract = {

The design and development of computational infrastructures supporting existing tele-laboratory experiences in the field of automation and robotics are described. The goal of the activity is to provide a proper e-learning environment in which remote laboratory experiences are integrated in a coherent way. The addition of e-learning features, as self-assessment and progress monitoring tools, asynchronous tutor interaction, authentication, evaluation and follow-up features, has led also to the modification of the original tele-laboratory set-up.

}, keywords = {Robotics}, author = {A. Balestrino and A. Bicchi and A. Caiti and V. Calabr{\`o} and T. Cecchini and A. Coppelli and L. Pallottino and G. Tonietti} } @conference {BGGT05, title = {Hybrid Modelling of an Electronically Controlled Limited Slip Differential}, year = {2005}, month = {8-10 September}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and G. Greco and M. Guiggiani and G. Tonietti} } @article {BCPT03, title = {On-line Robotic Experiments for Tele-Education at the University of Pisa}, journal = {Int. Journal of Robotic Systems}, volume = {22}, number = {4}, year = {2005}, note = {

Special Issue on Internet \& Online Robots for Telemanipulation

}, pages = {217-230}, abstract = {

In this paper we describe work being done at our department to make the Robotics Laboratory accessible to student and colleagues, to execute and watch real-time experiments at any time and from anywhere. We describe few different installations, and highlight the underlying philosophy, wich is aimed at enlarging the lab in all the dimensions of space, time, and available resources, through the use of Internet technologies.

}, keywords = {Robotics}, author = {A. Bicchi and A. Caiti and L. Pallottino and G. Tonietti} } @conference {IARP05, title = {Physical Human-Robot Interaction in Anthropic Domains: Safety and Dependability}, booktitle = {Proc. 4th IARP/IEEE-EURON Workshop on Technical Challenges for Dependable Robots in Human Environments}, year = {2005}, abstract = {

In this paper we describe the motivations and the aim ofthe EURON-2 research project {\textquoteleft}{\textquoteleft}\underline{P}hysical \underline{H}uman-\underline{R}obot \underline{I}nteraction in Anthropic \underline{Dom}ains{\textquoteright}{\textquoteright} (PRHIDOM). This project, which moves along the lines indicated by the 1$^{st}$ IARP/IEEE-RAS Workshop on Technical Challenge for Dependable Robots in Human Environments \cite{iarp01}, is about {\textquoteleft}{\textquoteleft}charting{\textquoteright}{\textquoteright} the new {\textquoteleft}{\textquoteleft}territory{\textquoteright}{\textquoteright} of physical Human-Robot Interaction (pHRI). To ensure these goals, the integration competences in control, robotics, design and realization of mechanical systems, human-machine interaction, and in safety-dependability of mechatronic systems is required. The PHRIDOM Consortium is composed of 5 partners from 3 different European countries.

}, keywords = {Robotics}, author = {A Albu-Schaeffer and A. Bicchi and G. Boccadamo and R. Chatila and A. De Luca and De Santis, A and G. Giralt and G. Hirzinger and V. Lippiello and R. Mattone and R. Schiavi and B. Siciliano and G. Tonietti and L. Villani} } @article {BT03, title = {Fast and Soft Arm Tactics: Dealing with the Safety-Performance Trade-Off in Robot Arms Design and Control}, journal = {IEEE Robotics and Automation Magazine}, volume = {11}, number = {2}, year = {2004}, note = {

PUBLISHER{\textquoteright}S NOTE: In this paper, there are three errors introduced during production. First, the correct title of the article is Fast and Soft Arm Tactics. Also, on formulae for GSI and HIC in page 23, the acceleration is measured in multiples of the acceleration of gravity (g) [not grams], while time is measured in seconds. Finally, within Figure 1, one should read Compliant Covering, and Mrob = Mrotor + Mlink [instead of Krob = Krotor + Klink]. Please visit http://www.ncsu.edu/IEEE-RAS/RAM/BicchiFigure1.pdf to see the original figure.

}, pages = {22{\textendash}33}, abstract = {

In this paper we discuss the problem of achieving good performance in accuracy and promptness by a robot manipulator under the condition that safety is guaranteed throughout task execution. The particular but basic problem of single-joint actuation is considered in detail. Intuitively, while a rigid and powerful structure of the arm would favour its performance, lightweight compliant structures are more suitable to safe operation. The quantitative analysis of the resulting design trade-off between safety and performance is one of the objectives of our work. Such analysis has a strong impact on how robot mechanisms and controllers should be designed for human-interactive applications. We discuss few different possible concepts for safely actuating joints, and focus our attention on one, the Variable-Stiffness Transmission (VST) approach. Some aspects related to the implementation of the mechanics and control of VST joints are reported.

}, keywords = {Robotics}, author = {A. Bicchi and G. Tonietti} } @article {1755, title = {Meccanismo motoriduttore a rigidezza variabile e rapidamente controllabile}, year = {2004}, address = {Italy}, keywords = {Robotics}, issn = {PI2004A000077}, author = {A. Bicchi and G. Tonietti} } @conference {BBCCPPT04, title = {A Robotic Set-Up with Remote Access for {\textquoteleft}{\textquoteleft}Pick and Place{\textquoteright}{\textquoteright} Operations Under Uncertainty Conditions}, booktitle = {E-learning and Virtual and Remote Laboratories}, series = {Proc. VIRTUAL-LAB 2004}, year = {2004}, pages = {144{\textendash}149}, abstract = {

The work describes on-going work at the University of Pisa on the field of tele-laboratories and distance learning. In particular, the group is working at the evolution of existing tele-laboratory experiments in the field of robotics and control into learning units of a self-consistent didactic project. The pick-and-place system described has been designed to provide the set-up for robot arm motion planning with specific objectives and evaluation tools.

}, keywords = {Robotics}, author = {A. Balestrino and A. Bicchi and A. Caiti and T. Cecchini and L. Pallottino and A. Pisani and G. Tonietti}, editor = {P. Borza and L. Gomes and G. Scutaru} } @conference {BTS04, title = {Safe and Fast Actuators for Machines Interacting with Humans}, booktitle = {Proc. of the 1st Technical Exhibition Based Conference on Robotics and Automation, TExCRA2004, November 18-19, TEPIA, Tokyo, Japan -}, year = {2004}, pages = {(in press)}, abstract = {

This paper describes a new generation of actuators for robotic applications, and more generally for machines that are designed to interact with humans. Such actuators, called Variable Impedance Actuators, are designed to achieve fast motion control while guaranteeing safety of human operators in worst-case impact situation. The fundamental innovation is to implement safety by purely mechanical, passive means, to guarantee intrinsic safety, while active control is used to recover performance. The design concept, which is the subject of a patent application, has led to the experimental implementation of a Variable Stiffness Actuator. The effectiveness of the VSA has been recently validated theoretically and experimentally by authors.

}, keywords = {Robotics}, author = {A. Bicchi and G. Tonietti and R. Schiavi} } @inbook {BTBP03, title = {Variable Stiffness Actuators for Fast and Safe Motion Control}, booktitle = {Proceedings of the International Symposium on Robotics Research}, series = {Springer Tracts in Advanced Robotics (STAR)}, year = {2003}, publisher = {Springer Verlag}, organization = {Springer Verlag}, abstract = {

In this paper we propose Variable Stiffness actuation as a viable mechanical/control co-design approach for guaranteeing control performance for robot arms that are inherently safe to humans in their environment. A new actuator under development in our Lab is then proposed, which incorporate the possibility to vary transmission stiffness during motion execution, thus allowing substantial motion speed-up while maintaining low injury risk levels.

}, keywords = {Robotics}, author = {A. Bicchi and G. Tonietti and M. Bavaro and M. Piccigallo}, editor = {B. Siciliano and O. Khatib and Groen, F.} } @conference {TB02, title = {Adaptive Simultaneous Position and Stiffness Control for a Soft Robot Arm}, booktitle = {Proc. IEEE Int. Symp. Intelligent Robots and Systems}, year = {2002}, month = {October}, pages = {1992-1997}, abstract = {

In this paper, an independent joint position and stiffness adaptive control for a robot arm actuated by McKibbenartificial muscles is reported. In particular, {\em muscular} nd {\em dynamic} parameters of the system are supposed unknown. Adaptive control performance is tested in a one degree of freedom experimental setup and compared with PID control performance. The adaptive control scheme is then applied to a robot arm that is conceived to perform tasks in an anthropic environment. The adaptive control developed is such that performance of the robot arm is very similar to this of human arm. Experimental results are reported.

}, keywords = {Robotics}, author = {G. Tonietti and A. Bicchi} } @conference {TB02-IARP, title = {Design, Realization and Control of Soft Robot Arms for Intrinsically Safe Interaction with Humans}, booktitle = {Proc. IARP/RAS Workshop on Technical Challenges for Dependable Robots in Human Environments}, year = {2002}, month = {October}, pages = {79-87}, keywords = {Robotics}, author = {A. Bicchi and G. Tonietti} } @conference {BLT01, title = {Compliant design for intrinsic safety: general issues and preliminary design}, booktitle = {Proc. IEEE Int. Symp. Intelligent Robots and Systems}, year = {2001}, month = {October}, pages = {1864-1869}, address = {Maui, Hawaii}, abstract = {

In this paper, we describe some initial results of a project aiming at development of a programmable-compliance, inherently safe robot arm for applications in anthropic environmnets. In order to obtain safety in spite of worst-case situations (such as unexpected delays in teleoperation, or even controller failure), we will consider achieving compliance by mechanical rather than by control design. We first describe some of the control problems that the presence of large, possibly unknown mechanical compliance typically introduces, and present a result that shows the possibility to cope with these uncertainties in an adaptive way. In the second part of the paper we describe the initial development of a new prototype arm under construction in our laboratory. The arm is designed to achieve arbitrary position tracking in 3D with controlled effective compliance at the joints.

}, keywords = {Physical Human-Robot Interaction (pHRI), Robot Arms}, author = {A. Bicchi and S. Lodi Rizzini and G. Tonietti} } @conference {BLT01-iarp, title = {Compliant robot arm design for intrinsic safety}, booktitle = {Proc. IARP/RAS Workshop on Technical Challenges for Dependable Robots in Human Environments}, year = {2001}, pages = {100-106}, abstract = {In this paper, we describe some initial results of a project aiming at development of a programmable-compliance, inherently safe robot arm for applications in anthropic environmnets. In order to obtain safety in spite of worst-case situations (such as unexpected delays in teleoperation, or even controller failure), we will consider achieving compliance by mechanical rather than by control design. We first describe some of the control problems that the presence of large, possibly unknown mechanical compliance typically introduces, and present a result that shows the possibility to cope with these uncertainties in an adaptive way. In the second part of the paper we describe the initial development of a new prototype arm under construction in our laboratory. The arm is designed to achieve arbitrary position tracking in 3D with controlled effective compliance at the joints.}, keywords = {Physical Human-Robot Interaction (pHRI), Robot Arms}, author = {A. Bicchi and S. Lodi Rizzini and G. Tonietti}, editor = {G. Giralt and P. Corke} }