Impedance control of mobile manipulator with the stability to external force

Abstract

A method of the impedance control of a mobile manipulator with the stability to the external force acting on the workpiece is proposed. (1) It is assumed that the robot does not know the workpiece's desired trajectory and is commanded directly by the external force. (2) Different types of desired impedance are set to the workpiece and the vehicle; the workpiece behaves as a desired mass to the external force, and the vehicle responds to the input of its desired position as a typical linear second-order system. Thus, the manipulator responds to the fast change in the force and the vehicle responds to the slow change. (3) For the purpose of keeping the robot stable-preventing it from tumbling-to the external force, the vehicle's desired position is determined so that the robot's zero moment point may come nearest to the center of the supporting polygon. Accordingly, the vehicle moves toward the most stable position.