Control of the Walking Robots based on the ZMP Defined on the Ceiling

Abstract

This paper presents a new method for controlling legged robots during the multi support phase, where the robot may have hand contact with the walls, in addition of feet supported on ground. We present an alternative way to define the zero moment point (ZMP), in order to derive a simpler control method. By selecting a virtual horizontal surface over the robot, we define the ZMP on this surface. The relation between the virtual surface, reaction force and body motion can be formulated in a similar way with the motion of a mass suspended by a wire. The motion of mass can be controlled by manipulating the position of ZMP and by adjusting the position of lifting hook along the virtually defined ceiling. The proposed control algorithm is verified in the real hardware of prismatic joint biped robot. The experimental results show a good performance of the proposed control method.