A proposal of right and left turning mechanism for quasi-passive walking robot

Passive walking robots are originally suggested to be walking down shallow slopes without any actuators and controllers. Most researches of passive bipedal robots have only be focused on walking on a straight line, although one of the important issues of walking robots is to move ahead for a target direction as they desired. The purpose of this paper is to develop direction control mechanism for an upper body driven quasi-passive 3D walking robot which can turn right and left on a flat surface. A walking gait of our 3D robot has a rolling motion from side to side of both legs on a frontal plane which synchronizes a pitching motion of a swing foot on a sagittal plane. Switching directions are made by a yawing motion mechanism which is attached on a hip joint above each leg. This mechanism makes use of yawing motion of the stance leg.