Experimental study of walking motion stabilization for biped robot with flexible ankle joints

This paper describes an approach of motion stabilization for biped robots with flexible ankle joints. The flexible joints cause the resonant oscillation under conventional control. In our approach, the deviated center of gravity (COG) due to the ankle´s deflections is measured in real-time by laser distance sensor mounted on the hip. Assuming the two mass model at COG, the equivalent reaction force relating to COG deviation is used as feedback signal for vibration control. At the same time, the influence of the response delay and yaw moment while walking is suppressed by the proposed motion regulator for posture stabilization. The proposed walking motion controller is evaluated experimentally under the walking pattern based on the inverted pendulum model without double support phase. The experimental results show the importance of the posture regulation in addition to the COG control.