abstract
- This study introduces an adaptive output-based controller for regulating the movement of a gripper actuated by bimorph piezoelectric actuators (BPZAs). The controller design incorporates the electromechanical characteristics of beam-like BPZAs with uniform cross sections made of single-crystal piezoelectric material. It is based on a robust sliding mode control framework with an adaptive gain mechanism that optimizes energy consumption. The proposed approach explicitly accounts for the dynamics of the analog current¿direct current (AC-DC) power converter driving the BPZA. The adaptive gain of the proposed controller is adjusted online based on the tracking error and hysteresis effects, which are estimated using a super-twisting robust differentiator. A cyberphysical representation of the BPZA is developed using the Galerkin discretization method to evaluate the effectiveness of the controller. The discretized BPZA dynamics are then tested using the designed control strategy. Experimental validation, including a microscopic image analyzer in the feedback loop for gripper positioning, confirms the robustness of the controller despite uncertainties in the actuator's mathematical model and nonlinear hysteresis. The results demonstrate that the proposed controller outperforms traditional proportional¿integral derivative (PID) controllers and their adaptive gain variants. Under all experimental conditions tested, the maximum mean square error for the tracking error remains below 1%, highlighting the controller's superior tracking performance and energy efficiency. © 2025 Chinese Automatic Control Society and John Wiley & Sons Australia, Ltd.