Online walking pattern generation for push recovery and minimum delay to commanded change of direction and speed

Abstract

A walking biped robot is required to change its walking direction and speed with minimal delay and not to tip off even when subjected to an unexpected external force. A major drawback of Zero Moment Point (ZMP) based online walking pattern generation methods is that arbitrary ZMPs cannot be achieved without divergence of the Conter of Mass (CoM). In this paper, we propose a new online walking trajectory generation method that utilizes nondivergence conditions of ZMP-CoM in a successive manner. This method enables changes in the walking direction and speed of a robot and push recovery under an unknown external force in unifie form. Experiments confir walking change of up to 4.05 km/h in the speed and changes in the walking direction with minimum delay and successful push recovery under an implse of 22 Ns.