Tracking control of a piezoelectric actuator with hysteresis compensation using RST digital controller

Piezoelectric actuators generally exhibit nonlinear hysteresis characteristics. The compensation of hysteresis is mandatory for improving the tracking control accuracy of the piezoelectric actuator system. This paper proposes a robust RST digital feedback controller in order to compensate hysteresis nonlinearity and subsequently to improve the tracking control accuracy of the piezoelectric actuator system. To design the proposed controller, first the dynamics of the considered piezoelectric actuator system is identified experimentally. Then, a controller is designed based on pole placement with sensitivity functions shaping methodology and applied to piezoelectric actuator system. The performance of the proposed controller is compared with a general approach of using inverse Prandtl-Ishlinskii hysteresis model as a feed-forward controller. The achieved experimental results with proposed RST digital feedback controller show improved performances with respect to those obtained with inverse Prandtl-Ishlinskii hysteresis model in overall suppressing the hysteresis nonlinearity by 96.5% and reducing the peak-to-peak tracking error by 93.6%. The peak to peak tracking error of less than 2% for the desired displacement of 18 \(\upmu\)m with tracking frequency of 10 Hz is also achieved. These experimental results validate the effectiveness of the proposed control scheme.