A Miniature Traveling Wave Ultrasonic Linear Motor Utilizing Bimorph Transducers

Scaling down linear actuators is crucial for various industrial applications, yet the efficiency of electromagnetic linear actuators decreases significantly as they are miniaturized. Millimeter-scale miniature ultrasonic motors, on the other hand, maintain high efficiency. This article describes a new approach to facilitate the miniaturization of traveling wave linear ultrasonic motors by attaching bimorph transducers to the ends of the stator beams. To control the resonance frequency and facilitate the generation of a traveling flexural wave in the beam, grooves are incorporated into the bimorph structure. Mechanical output is improved by amplifying the transverse displacement through the addition of teeth to the beam. Utilizing the finite element method (FEM), a prototype measuring $10\times 10\times 160$ mm was designed, fabricated, and tested. It achieved an output speed of 53.7 mm/s and a thrust of 0.83 N at a peak-to-peak voltage of 300 V and a frequency of 32.7 kHz. The results show that the proposed ultrasonic linear motors with small size, simple structure, and overall compactness have promising applications in robotics, precision machining, medical equipment, and other fields requiring miniature compact linear motions.