Design and dynamic analysis of a novel compound bending hollow piezoelectric beam miniature rotary actuator

In this paper, a miniature hollow piezoelectric beam rotary actuator is proposed and designed based on the compound bending vibration modes. The structure body is designed as an elastic hollow square beam with symmetrical piezoelectric patches attached at both ends, which directly eliminates the step of the frequency tuning. A conical rotor is driven by the hollow piezoelectric beam through the elliptical motions of the points on its inner surface. Based on the Timoshenko beam theory and Lagrange equation, the numerical continuum model is established to analyze the working mechanism. A prototype of the miniature rotary actuator with a size of 50 × 6 × 6 mm (2 mm through-hole) is manufactured and its performance under various excitation parameters is characterized in rotor speed experiments. The experimental results show that the maximum speed of the conical rotor is 913 rpm at the excitation voltage of 400 V. With a maximum load of 70.31 mN, the spherical rotor can achieve a speed of 450 rpm. The numerical results are in great agreement with the experimental results, so the output characteristics of the rotary actuator can be estimated. The simulation and test results demonstrate that the proposed rotary actuator has outstanding output performance and controllability. In addition, the simple structure design is easy to realize the frequency tuning and miniaturization.