Apex height control of a four-link hopping robot

Bipedal robots have the potential to provide robust locomotion over uneven terrain and its dynamic stability has been shown to be analogous to that of a spring loaded inverted pendulum (SLIP). The SLIP model is fundamentally limited in its ability to accurately represent legged locomotion since it does not take into account the impulsive dynamics of foot ground interaction. In this paper we investigate the control of a four-link hopping robot based on the complete dynamics of the system. Using partial feedback linearization to control the configuration in continuous time, and discrete parameter variations the control object of apex height control of the robot is achieved. Simulation results are presented to show the efficacy of the control scheme.