Online Center of Mass Detection for Quadruped Robots in Trot Gait Motion*

Abstract

Most of the motion control strategies for the quadruped robots are based on the trajectory planning of the center of mass (CoM) and the hypothesis that the CoM locates at the geometrical center of the trunk. In fact, the CoM position offsets will introduce obvious influence to the control performance. This paper presents a method for online CoM detection for quadruped robots running in trot gait. The dynamical model of the robot is built in the inertial coordinate system. Transforming methods for the status variables from the base frame to the inertial frame are also provided. To get more precise results, the step height compensation method for swing feet and comparative ground reaction force calculations are presented. With the proposed method, the analytical solution of the CoM position is obtained. Simulations show the effectiveness of the proposed method.