3-D Biped Walking Using Double Support Phase and Swing Leg Retraction Based on the Assumption of Point-Contact

This paper describes 3-D biped walking control based on the assumption of point-contact. We previously realized 3-D biped walking on unknown terrain using the Passive Dynamic Autonomous Control (PDAC) approach, which is based on the assumption of pointcontact of a robot foot and virtual holonomic constraint as to robot joints. However, the stable range of walking is narrow and the robustness of walking is not enough for practical use. In order to increase the robustness of walking, we propose swing leg retraction and double support phase in this paper. Swing leg retraction facilitates the stabilization ability of PDACbased walking; also, by use of the double support phase, robot dynamics converges to stable orbit even if disturbance happens at foot-contact. Finally, the proposed biped walking algorithm is verified by numerical simulation and experiments.