Dynamics morphing from regulator to oscillator on bipedal control

A stable non-linear oscillator for autonomous biped stepping control is designed in a top-down manner by morphing dynamics of standing regulator. It resolves three problems which have been in the conventional artificial CPG approaches, namely, (1) how to unify it with the standing control, (2) the controller parameter tuning with complicated networked unit oscillators, and (3) a design of an extra sensory feedbacks to be superimposed for stabilization. The proposed control is built upon the stabilizability-maximized COM-ZMP regulator developed by the author, and only a single parameter seamlessly connects it to a stable limit cycle without degrading the stabilization performance. By synchronizing the foot-lifting with a limit cycle of ZMP, a stable periodic alternate stepping is achieved. Since it is free from time-driven trajectory, it is expected to be a fundamental technique to build robust autonomous biped controllers.