Yet another humanoid walking - passive dynamic walking with torso under simple control

Passive dynamic walking (PDW) has received an increasing attention as a simple walking method with no or very little control, thus requiring a small amount of energy consumption. To the best of our knowledge, there are no PDW models with a torso although there have already been many studies on PDW. This paper presents the first step towards applying the PDW principle to humanoid robots by adding a torso to a conventional PDW model. The computer simulation shows that the walking of the PDW robot converges at a stable gait cycle only with a simple PD control applied between the torso and the stance leg to stand the torso up. Three attempts have been tested to reduce the torque to stand the torso up by: changing the desired posture of the torso, adding the soft leg tips, and changing the curvature of the sole. Simulation results are shown and discussed.