Safe Adaptive Switching among Dynamical Movement Primitives: Application to 3D Limit-Cycle Walkers

Abstract

Complex robot motions are frequently generated by composing simpler primitive movements. We use this approach to formulate robot motion plans as sequences of primitives to be executed one after the other. When dealing with dynamical movement primitives, besides accomplishing the high-level objective, planners must also reason about the effect of the plan's execution on the safety of the platform. This task is exacerbated by the presence of disturbances, such as non-vanishing external forces. To address this issue, we present a framework that builds on rigorous control-theoretic tools to generate safely executable motion plans for externally excited robotic systems. We illustrate the proposed framework on adapting the motion of a 3D bipedal robot model to persistent external forcing by switching among dynamic movement primitives, each corresponding to a limit-cycle walking gait.