Passivity-Based Compliant Walking on Torque-Controlled Hydraulic Biped Robot

This paper presents an experimental evaluation of passivity-based whole-body motion control framework for compliant walking. The controller computes joint torques without requiring much computation cost and contact force measuring. Instead of limiting the walking speed slow (static walking), in this work we specifically address the difficulties of walking on unstable and uneven ground. No terrain information is used in the experiments, that is, the ground is assumed to be flat, and the desired motion trajectories are given offline. With this setup we evaluate the terrain adaptability by force control alone. The controller is applied to our torque-controllable hydraulic humanoid robot, TaeMu. The robot could walk on a rocker board stably, and even climbed the small step with a little modification of the controller (quasi-dynamic walking).