Modeling and controlling a rotary piezo actuator

Abstract

In this study, a novel piezo rotary stick–slip actuator was designed and investigated. This approach employs two piezo actuators to deform a flexible mechanism in order to generate a variable stick-and-slip force that drives the rotor. The compliant mechanism is composed of the bridge amplifiers and lever mechanism. They are arranged in sequence to amplify the piezo actuator's displacement. Hence, the operating range of the actuator, which includes rotation speed and resolution, can be increased. To optimize the fundamental dimensions of the actuator, the method of finite elements was investigated. The mechanical structure is detailed, the operating principle is elucidated, and a dynamic model is developed. From experimental data, the dynamic model of the structure is identified. The actuator achieves an angular displacement resolution of 0.028 degree at an applied voltage of 45 V and an operating frequency range up to 140 Hz, allowing it to be employed in applications requiring high precision positioning. Besides, the closed-loop control scheme is proposed to control the actuator in both directions. The simulation and experimental results have demonstrated that the position of the stick–slip actuator can be effectively controlled through this proposed controller. This is expected to increase the potential application of the stick–slip actuator in industrial practice.