TeleImpedance: Exploring the role of common-mode and configuration-dependant stiffness

Humans explore and adapt neuro-motor strategies to cope with limitations of multi-joint impedance regulation mechanism. For instance, predictive control of degrees of redundancy further regulates the endpoint impedance in addition to co-contractions. Inspired by these observations, this paper proposes a novel Tele-Impedance algorithm that replicates the human's arm endpoint stiffness in robot by controlling the common-mode and configuration-dependant stiffness. Design of the controller and its stability is addressed and experimentally evaluated in robotic peg-in-hole task. Results of the proposed method are compared to the ones derived from Tele-Impedance implemented using classical Cartesian stiffness control. The interaction performance achieved highlights the possibility of adopting common mode stiffness in robots with adequate degrees of redundancy, in order to realize the desired task space impedance.