A sustainable running criterion for biped balance control

Abstract

This paper aims at exploring a novel criterion for sustainable running of biped robots subject to external perturbations. A new notion of running-feasible state is introduced to ensure that a biped can sustain a running motion starting from this state by an allowable control. Then a running-feasible set is estimated by using the orbit energy and the symmetric property of the inverted pendulum model. Based on the developed sustainable running criterion, a non-periodic reference trajectory is generated within a running-feasible set for disturbance rejection in real time and a control law is then designed to track the reference trajectory. In simulation, a five-link, four-actuator biped transits its speed between 2.8 m/s and 4.8 m/s in responding to external disturbances of pushing forward and backward. The simulation results confirm the effectiveness of balance recovery in a running biped, resembling the reaction pattern of a human being.