Impedance Control of the Hydraulic Shoulder A 3-DOF Parallel Manipulator

Abstract – In this paper, a model-based impedance control strategy is developed for a 3 DOF parallel manipulator to manage the interaction of the robot with the environment. Kinematic and dynamic modeling of the manipulator has been analyzed in order to be used for both simulation and control purposes. The impedance controller objective and the structure of the proposed controller are introduced and controller gain selection is discussed. A simulation study evaluates the effectiveness of the proposed impedance control structure. It is observed that although the proposed controller is designed for impedance adjustment of the robot, in case of free motion, it results into desirable position tracking. Moreover, when the robot comes into contact with the environment, the interaction dynamics can be regulated regardless of the nonlinear dynamics of the robot. Index Terms – Parallel manipulator, impedance control, model-based control, stiff environment. I