Walking on Uneven Terrain with Passivity-Based Contact Force Control on Torque-Controlled Hydraulic Biped Robot

Abstract

This paper presents the application of our passivity-based whole-body contact force control framework to compliant walking. We experimentally evaluate the performance of the controller using our original torque-controllable hydraulic humanoid robot, TaeMu. The experiments are performed on the postural stabilization against support space tilt disturbance and walking on the uneven and unstable ground. Instead of limiting the walking speed slow, we address the terrain adaptability of the proposed robot system and algorithm. For that purpose, prior terrain information and environment perception are not given to the controller. The desired motion trajectories are given in advance on the assumption of the ground to be flat. Nevertheless, the robot was able to compliantly keep its posture, compliantly walk on small steps and on an unstable rocker board laid lengthways or crossways. The results demonstrate the effectiveness of the proposed controller as well as the robotic hardware.