Exponentially stable periodic walking of under-actuated biped robot

Abstract

<p indent="0mm">The biped robots have characteristics of strong environmental adaptability, complex structure and difficult motion control. This paper addresses the problem of exponential stable walking of a five-link under-actuated biped robot (RABBIT) through control Lyapunov function and hybrid zero dynamics. The walking system is input-output linearized after the full-order dynamic model is described with Lagrange dynamic equations. Based on hybrid zero dynamics, a state feedback controller is then utilized to realize exponential stability of periodic orbit by designing control Lyapunov function, which is proved to be exponentially stable by restricted Poincare Return Map. The effectiveness of the mentioned method is illustrated by simulations.