A Frog-Shaped Linear Piezoelectric Actuator Using First-Order Longitudinal Vibration Mode

A frog-shaped linear piezoelectric actuator was proposed, designed, fabricated, and tested. The proposed actuator only used the first-order longitudinal vibration to generate linear motion, which made the design, optimization, and miniaturization of the actuator more flexible by abbreviating the frequency degeneration. By stimulating the first-order longitudinal vibration, alternate oblique movements are formed on the ends of two driving feet. Meanwhile, an elongating and shortening movement of the whole actuator is generated. When two parallel walls are in contact with the ends of two diving feet and a vertical preload is applied, the vertical components of the alternate oblique movements will overcome the preload, while the horizontal components of the alternate oblique movements and the elongating and shortening movements will together push the actuator into linear motion. Vibration characteristics and alternate oblique movements of the driving feet were investigated by the finite-element method. Experiment tests of vibration characteristics and mechanical output ability were then carried out. The tested resonance frequency and vibration amplitudes agreed well with the calculated ones. The prototype achieved a maximum speed and a thrust of 287 mm/s and 11.8 N, respectively.