01804nas a2200193   4500008004100000245012300041210006900164260003900233300001400272520106400286653002101350653004401371653001301415100001601428700001401444700001501458700001501473856012201488       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<p>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.</p>
10aEmbedded Control10aPhysical Human-Robot Interaction (pHRI)10aRobotics1 aDe Luca, A.1 aFlacco, F1 aSchiavi, R1 aBicchi, A.  uhttp://95.110.227.47/publications/nonlinear-decoupled-motion-stiffness-control-and-collision-detectionreaction-vsa-ii