Control and Testing of a Serial-Parallel XYZ Precision Positioner with a Discrete-Time Sliding Model Controller

This paper reports the control and testing of a serial-parallel piezo-actuated XYZ precision positioner. The XYZ positioner mainly consists of a Z stage connected with the parallel XY stage in series. The XYZ positioner was fabricated through wire electrical discharge machining, and system identification was performed to obtain the dynamic model of the system. In order to further improve the performance of positioner, a discrete-time sliding model (DSM) controller with PID sliding surface is proposed to achieve precision position control. The proposed controller has the advantage of fast response, strong robustness. A number of experiments have been carried out to verify the performance of positioner and effectiveness of proposed DSM controller. The results indicate that the positioner can implement a workspace of 85.4 × 87.5 × 11.9 μm3 with coupling errors less than 1.56% in the non-working direction, and good spatial trajectory tracking performance and high positional accuracy can be realized through the proposed control strategy.