A novel inchworm type piezoelectric rotary actuator with large output torque: Design, analysis and experimental performance

A novel inchworm type piezoelectric rotary actuator based on wedge block clamping is presented in this paper. With the help of only one piezo-stack and two clamping blocks, the proposed actuator can imitate the walking mode of inchworm to deliver stable long range rotary motion accompanying with high driving resolution. Owing to the advantages of the distinctive clamping principle, the output torque of the actuator can be up to 7168.7 Nmm. The mechanical structure and the working principle of the actuator are introduced in detail. As a key component of the actuator, the clamping block is well designed and the curve function of its working surface is deduced. We manufacture an actuator prototype and establish a set of experimental system and conduct a series of experiments to test the performance of the prototype. The experimental results indicate that the prototype can output stable angular displacements step by step under various driving voltages and frequencies and all steps have high reproducibility. The driving resolution of the actuator is 0.567 μrad and the designed motion range is 5°. We can obtain a satisfactory driving velocity by choosing a proper driving voltage and frequency for the actuator. Under driving frequency of 1 Hz, the maximum velocity is 511.7 μrad s⁻¹ when the driving voltage is 150 V and under driving voltage of 90 V, the velocity can reach to 42959.5 μrad s⁻¹ when the driving frequency is 128 Hz.