We designed a four-legged linear ultrasonic motor with a new structure. It uses the in-plane first-order longitudinal vibration mode and the out-of-plane anti-symmetric vibration mode, which are superimposed to produce linear motion. The motor consists of a stator and four groups of eight piezoelectric ceramic sheets. Under the excitation of a two-phase high voltage signal, the out-of-plane bending vibration and in-plane longitudinal vibration are generated in the stator. These vibrations alternately drive the motor through the front two driving feet and the back two driving feet, which leads to an elliptical motion. Thus, the four feet can effectively drive a slider to move in a straight line. An experimental prototype was fabricated with a size of 600 × 160 mm. The experimental results show that with a 200 V driving voltage, the maximum translational speed can reach 135 mm/s and the maximum thrust is 3.6 N. The motor has the advantages of simple structure and high output efficiency, which make it have a good prospect in precision systems and industrial applications.

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