Input-to-State Stable Bilateral Teleoperation by Dynamic Interconnection and Damping Injection: Theory and Experiments

Abstract

In bilateral teleoperation, the human operating the master and the environment interacting with the slave are part of the force feedback loop. Yet, both have time-varying and unpredictable dynamics and are challenging to model. Conventional sidestepping of the demand for their models in the stability analysis assumes passive user and environment, and controls the master-communications-slave system to be passive too. This paper circumvents the need for user and environment models in a novel way: it regards their forces as external excitations for a semiautonomous feedback loop, which it outfits with a dynamic interconnection and damping injection controller that renders time-delay teleoperation exponentially input-to-state stable. The controller uses the position and velocity of the local robot and the delayed position transmitted from the other side to robustly synchronize the master and slave under the user and environment perturbations. Lyapunov-Krasovskii stability analysis shows that the strategy, first, can confine the position error between the master and the slave to an invariant set, and, second, can drive it exponentially to a globally attractive set. The approach has practical relevance for telemanipulation tasks with given precision requirements. Experiments with a pair of Geomagic Touch robots validate the strategy compared to state-of-the-art robust position tracking designs.