01808nas a2200193 4500008004100000245012300041210006900164260003900233300001400272520106400286653002101350653004401371653001301415100001601428700001401444700001501458700001501473856012601488 2009 eng d00aNonlinear Decoupled Motion-Stiffness Control and Collision Detection/Reaction for the VSA-II Variable Stiffness Device0 aNonlinear Decoupled MotionStiffness Control and Collision Detect aSt. Louis MO USAcOctober, 11 - 15 a5487-54943 a

Variable Stiffness Actuation (VSA) devices are being used to jointly address the issues of safety and performance in physical human-robot interaction. With reference to the VSA-II prototype, we present a feedback linearization approach that allows the simultaneous decoupling and accurate tracking of motion and stiffness reference profiles. The operative condition that avoids control singularities is characterized. Moreover, a momentum-based collision detection scheme is introduced, which does not require joint torque sensing nor information on the time-varying stiffness of the device. Based on the residual signal, a collision reaction strategy is proposed that takes advantage of the proposed nonlinear control to rapidly let the arm bounce away after detecting the impact, while limiting contact forces through a sudden reduction of the stiffness. Simulations results are presented to illustrate the performance of the overall approach. Extensions to the multi-dof case of robot manipulators equipped with VSA-II devices are also considered.

10aEmbedded Control10aPhysical Human-Robot Interaction (pHRI)10aRobotics1 aDe Luca, A.1 aFlacco, F1 aSchiavi, R1 aBicchi, A. uhttp://175973.jxltd.asia/publications/nonlinear-decoupled-motion-stiffness-control-and-collision-detectionreaction-vsa-ii01575nas a2200265 4500008004100000245007700041210006900118300000900187520075100196653002100947653004400968653001301012100001501025700001401040700001701054700001701071700001701088700001501105700001801120700001201138700001501150700001101165700001601176856011701192 2008 eng d00aPhysical Human-Robot Interaction: Dependability, Safety, and Performance0 aPhysical HumanRobot Interaction Dependability Safety and Perform a9-143 a

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.

10aEmbedded Control10aPhysical Human-Robot Interaction (pHRI)10aRobotics1 aBicchi, A.1 aBavaro, M1 aBoccadamo, G1 aCarli, De, D1 aFilippini, R1 aGrioli, G.1 aPiccigallo, M1 aRosi, A1 aSchiavi, R1 aSen, S1 aTonietti, G uhttp://175973.jxltd.asia/publications/physical-human-robot-interaction-dependability-safety-and-performance.html01484nas a2200193 4500008004100000245006500041210006400106260003300170300001400203490000700217520082500224653004401049653001301093100001601106700001501122700001501137700003501152856010301187 2006 eng d00aOptimal Mechanical/Control Design for Safe and Fast Robotics0 aOptimal MechanicalControl Design for Safe and Fast Robotics bSpringer Berlin / Heidelberg a311 - 3200 v213 a

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.

10aPhysical Human-Robot Interaction (pHRI)10aRobotics1 aTonietti, G1 aSchiavi, R1 aBicchi, A.1 aMarcelo H. Ang, Oussama Khatib uhttp://175973.jxltd.asia/publications/optimal-mechanicalcontrol-design-safe-and-fast-robotics.html01815nas a2200217 4500008004100000245007700041210006900118260003300187300001400220490000700234520109300241653004401334653001301378100001701391700001501408700001101423700001601434700001501450700001901465856011301484 2006 eng d00aOptimization and Fail-Safety Analysis of Antagonistic Actuation for pHRI0 aOptimization and FailSafety Analysis of Antagonistic Actuation f bSpringer Berlin / Heidelberg a109 - 1180 v223 a

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.

10aPhysical Human-Robot Interaction (pHRI)10aRobotics1 aBoccadamo, G1 aSchiavi, R1 aSen, S1 aTonietti, G1 aBicchi, A.1 aChristensen, H uhttp://175973.jxltd.asia/publications/optimization-and-fail-safety-analysis-antagonistic-actuation-phri.html