Abstract
The authors have clarified the mechanisms and importance of semicircular feet on dynamic biped locomotion. This paper then investigates the effect of asymmetric shape of semicircular feet on biped walking speed. The rolling effect acts as the virtual ankle-joint torque during the stance phase; the heel-side effect propels the robot's center of mass (CoM) forward during the first-half of cycle, whereas the toe-side effect forces CoM backward during the second-half of cycle. The feet on the other hand reduce energy-dissipation caused by heel-strikes at instants of transition. These properties can be adjusted by changing the foot radius. The question then yields of which effect is more crucial for gait generation. Underactuated virtual passive dynamic walking is considered to generate a biped gait and its parametric studies are performed to clarify the mechanisms of semicircular feet with various foot radius.
