Design and Experimental Evaluation of a Stepper Piezoelectric Actuator Using Bending Transducers

A stepper piezoelectric actuator, in which two bending transducers were used to push a runner step-by-step alternatively, was proposed and tested in this paper. Each bending transducer can bend in horizontal ( $X$ ) direction and vertical ( $Y$ ) direction, independently. The bending motion of the transducer in the vertical direction was used to control the contact state between the driving tip and the runner; the linear stepper movement of the runner was accomplished by the horizontal bending motion of the transducer when the driving tips is contacting with the runner. The piezoelectric actuator can realize linear stepper motion by designing the sequences of the bending motions of the two transducers. The operating principle of the stepper driving was illustrated and discussed in detail. A finite-element method was used to simulate the motion trajectories of the driving tips. A prototype was fabricated to verify the operating principle, and the mechanical output characteristics were measured. The runner was pushed linearly step-by-step under four square wave signals with temporal shifts, a maximum no-load speed of $227.3~\mu \text{m}$ /s was achieved, and the maximum output thrust force was tested to be about 14 N. The proposed piezoelectric actuator achieves long stroke, large output force, and precision driving by using two non-resonant bending transducers.