Robust impedance control of a piezoelectric stage under thermal and external load disturbances

Piezoelectric actuators are widely used in micromanipulation tasks such as atomic force microscopy and cell manipulation. However, the hysteresis nonlinearity and the creep reduce their fidelity and cause difficulties in the micromanipulation control procedure. Besides, variation of temperature and external loads could change the model parameters identified for the piezo actuator. In this paper, a novel feedforward-feedback controller is proposed. The modified Prandtl-Ishlinskii model is utilized to linearize the actuator hysteresis in feedforward scheme and a sliding mode based impedance control with perturbation estimation is used to cancel out the thermal and external load disturbances in feedback scheme. The efficiency of the proposed controller is verified by experiments.