A dual-mode excitation method of flexure hinge type piezoelectric stick-slip actuator for suppressing backward motion

Backward motion directly limits the output performance of piezoelectric stick-slip actuators, and it has been suppressed or eliminated by various means. To suppress the backward motion, a dual-mode excitation method (DMEM) is proposed in this paper, which utilizes a piezoelectric stack and two piezoelectric plates as the main and auxiliary excitation sources of the actuator respectively. When the piezoelectric stack contracts rapidly under the traditional sawtooth wave, two piezoelectric plates excited by high-frequency sine wave make the driving foot generate ultrasonic vibration. Accordingly, the backward motion can be suppressed based on ultrasonic friction reduction to improve the output performance of actuator. To reflect the advantage of the proposed method, a flexure hinge type piezoelectric stick-slip actuator is manufactured, and the characteristic experiments are executed. According to the experimental results, the backward rates of actuator driven only by sawtooth wave are 42 % and 28 % in the clockwise and counterclockwise directions, the corresponding velocities are 252.74 mrad/s and 316.45 mrad/s, the corresponding loads are 8 g and 9 g, respectively. By comparison, the backward rates of actuator under the DMEM decrease by 10 % and 5 % along these two directions, the velocities improve by 17 % and 9 %, and the loads increase by 13 % and 11 %, respectively.