A unified approach to ZMP and gravity center control in biped dynamic stable walking

Summary form only given. In this paper, to realize dynamic stable walking, a novel control strategy is formulated, which is based on both the centre of gravity (COG) and the zero moment point (ZMP) of the biped supporting leg control. This control algorithm involves the following two stages: 1) trajectory generation of the ZMP for the realization of the arbitrary COG trajectory; and 2) the ZMP controller which directly control the ZMP of the supporting foot. The ZMP trajectory is generated according to the tracking error of the COG and based on the fuzzy logic. This algorithm makes it possible to realize the arbitrary COG trajectory by the position command of the ZMP which satisfies the dynamic walking stability with no consideration of nonlinear relationship between the ZMP and COG. The ZMP of the supporting foot is controlled directly by the proposed ZMP controller even if unknown external force imposes on the robot. The experimental results of a 6-DOF biped walking robot in sagittal plane are presented.