Design and experimental evaluation of a novel stepping linear piezoelectric actuator

A novel stepping piezoelectric actuator is proposed and tested in this work to achieve the linear driving with long stroke and high resolution. The proposed piezoelectric actuator contains four piezoelectric stacks located in U-shape: two of them are set horizontally, whereas the other two are placed vertically. The actuating principle of the U-shaped actuator is analyzed: two piezoelectric stacks are used to control the clamping state of the runner, while the linear stepping motion is achieved by the other two stacks. A double-level screws structure, which not only gives enough preload, but also protects the piezoelectric stacks from lateral forces, is proposed and used to make the piezoelectric stacks work under a reliable condition. An equivalent model is developed for the calculation of the clamping force of the piezoelectric actuator. The equivalent model is based on a concept of converting structures related to clamping forces into springs with certain elastic coefficients. Static analysis is performed by finite element method (FEM) to get the equivalent coefficients of the structures. A prototype is fabricated and the experimental studies are carried out to validate the actuating principle and obtain the mechanical output performances. Experimental results show that the maximum driving force of the prototype is 13.2 N and the maximum velocity is 47.6 μm/s.