Design, analysis, and experiment of a piezoelectric stick-slip rotary actuator with asynchronous-driven dual stators

The piezoelectric stick-slip actuator with a compact structure shows great merits for spacecritically limited applications, such as high-precision positioning and micro-nano operations. It can be used as a rotating part in micro-nano manipulators. However, piezoelectric stick-slip actuators operate under the friction-inertia principle. The backward motion is almost inevitable at low driving frequencies, hugely detrimental to manipulation accuracy, thus posing challenges to the configuration design and driving strategy of the actuator. This paper proposes a stick-slip rotary actuator with asynchronous-driven dual stators. Based on the principle of minimum motion branch chains and piezoelectric stacks, a dual-stator stick-slip rotary actuator with 2-R forcecouple flexible stators is designed to enhance structure compactness. Then, an asynchronous driving method is proposed that enables the actuator to increase stickiness and reduce slippage without changing the driving waveform to minimize the backward motion. After that, the kinetic model with electromechanical-frictional coupling properties is developed, and the motion and load characteristics of the actuator are analyzed through MATLAB/Simulink simulations. The causes of the motion and load characteristics are discussed, and measures to improve the motion speed and load capacity are proposed. Finally, a prototype is fabricated, and several experiments are carried out. The results show that the backward motion of the actuator is significantly suppressed in the asynchronous driving mode, and its output displacement exhibits good stepping characteristics. The actuator has the advantages of a simple structure, little volume, small backward motion, and high resolution, demonstrating structural and performance superiorities for micro-nano manipulators in space-constrained applications.