A PD control scheme for passive dynamic walking based on series elastic actuator

Using a complaint actuator is necessary and one of the most important factor for a passive biped robot to get a natural gait which is an unique feature of `passive dynamic walking´, so how to control the complaint actuator well is very important. In this paper we choose the Series Elastic Actuator (SEA) as our complaint actuator, improve its structure, and propose a PD control scheme based on the SEA to obtain a higher control accuracy of the swing-leg´s desired angle and a more natural gait of the walking. We built a passive biped robot prototype with an upper body that is fully passive by using bisecting mechanism, and finally the PD control scheme was proved effective by both simulation and prototype experiment.