Efficiency Study of the Non-instantaneous Double Support Phase in HZD Controlled Bipedal Robot

A study on the influence of a non-instantaneous double support phase on the energy efficiency and the stability of a bipedal walking robot with hybrid zero dynamics control is performed. The planar robot model consists of five rigid body segments and four actuated revolute joints. The periodic gait includes two alternating continuous single and double support phases as well as two discrete transition events. Two virtual actuators are introduced to create one degree of under-actuation in the double support phase. Periodic solutions of the gait are found via the numerical optimization, which minimizes the energy consumption of locomotion. The resulted efficiency and stability are compared against the common model approach with instantaneous double support phase. Despite the less efficiency, the extended controller with non-instantaneous double support phase improves the gait stability, which could be beneficial for the experimental validation on a robot prototype.