Increasing the accuracy for a piezo-actuated micro manipulator for industrial robots using model-based nonlinear control

We consider the problem of modeling and control of the nonlinear dynamics of a micro manipulator, utilized for machining operations in combination with industrial robots. Position control of the micro manipulator is a challenging problem because of the actuation principle, which is based on piezo-actuators with inherent nonlinear behavior. The major nonlinearities in the manipulator are identified and explicitly modeled in this paper. Different model structures are outlined and subsequent identification experiments are performed and evaluated. The obtained models form the basis for a combined feedforward and feedback control scheme for accurate position control. Experimental results obtained with the developed control scheme are presented and discussed. We show that the accuracy of the controller is increased significantly with the proposed scheme, compared to a linear controller.