Nonlinear control design of piezoelectric actuators with micro positioning capability

Inherently, piezoelectric actuator is one of the devices equipped with the micrometer positioning capability and characterized by small size, fast response, high stiffness, and large blocking force. These advantages give piezoelectric actuator the possibility of being high-accuracy industrial machineries. However, factors of nonlinear hysteresis, modeling uncertainties, and environmental disturbances result in unacceptable positioning errors and greatly increase the control difficulties. In this paper, a hybrid nonlinear robust control design that integrates a feedback linearization control method and a robust compensator is proposed. It aims to eliminate above-mentioned impacts and tackle the micrometer (μm) positioning design of piezoelectric actuators. The feedback linearization controller is developed for converging of positioning errors exponentially. The robust compensator is used to mitigate the total impact of hysteresis, modeling uncertainties and environmental disturbances and carry out the fine tuning of positioning errors to zero. Simulation results and practical tests reveal that the controlled piezoelectric actuator reaches 1 μm positioning accuracy, and the proposed robust control law delivers promising positioning performance under impacts of hysteresis, modeling uncertainties and environmental disturbances.