Design and analysis of a piezoelectric inchworm actuator

Abstract

Piezoelectric inchworm actuators are developed from the motion features of nature inchworm with the advantages of large stroke, high resolution and rigidity and flexible structure. They have a wide application in the fields of Nano positioning and ultra-precision detecting instruments. A new piezoelectric inchworm actuator based on the principle of flexible amplification is developed in this paper. In the moving mechanism of the actuator, its clamping mechanism adopts symmetrical lever amplification structure, and its middle drive mechanism uses compound bridge structure. Round and straight hinges are adopted to the design of the mechanism. Theoretical analyses, including stiffness, natural frequency, stress and deformation of the mechanism, are used to design the hinge structure which has influences on the properties of moving mechanism. Then finite element analysis is carried out to optimize the structure of the actuator. High precision cross roller guide ways are utilized to improve the positioning accuracy of the actuator. The laboratory platform of the piezoelectric inchworm actuator is built. The controlling program of the actuator is compiled by Lab-VIEW. The experimental results of the actuator are as follows. The working stroke of the actuator is 50 mm, the minimum step pitch is 60 nm, the maximum step pitch is 105 μm, the fast speed is 2.04 mm/s, the maximum clamping force is 21 N, the maximum stability load is 500 g, and the average speed of the actuator can still reach 1.47 mm/s when the driving frequency is 50 Hz and the load is 1 kg.