Balance control based on Capture Point error compensation for biped walking on uneven terrain

This paper tries to improve a balance control based on the Capture Point (CP) control. First the characteristics of the conventional balance controller are shown to be essentially the same as the CP controller. Then we analyze the transfer function of the balance controller. We introduce a new state variable with the CP integration to the CP and the ZMP (Zero-Moment Point) in order to trim a long term offset of the CP and the ZMP. Verification of the proposed balance controller is conducted through both simulation and experiments with a humanoid robot HRP-211.