D.J. Braun, F. Petit, F. Huber, S. Haddadin, P. Smagt, A. Albu-Schaffer, and S. Vijayakumar, Optimal torque and stiffness control in compliantly actuated robots, IEEE/RSJ International Conference on Intelligent Robots and Systems, Algarve, PT, pp. 2801–2808, October 2012.
Anthropomorphic robots that aim to approach human performance agility and efficiency are typically highly redundant not only in their kinematics but also in actuation. Variable-impedance actuators, used to drive many of these devices, are capable of modulating torque and passive impedance (stiffness and/or damping) simultaneously and independently. Here, we propose a framework for simultaneous optimization of torque and impedance (stiffness) profiles in order to optimize task performance, tuned to the complex hardware and incorporating real-world constraints. Simulation and hardware experiments validate the viability of this approach to complex, state dependent constraints and demonstrate task performance benefits of optimal temporal impedance modulation.