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Design of a Semi-Oval Shaped Ultrasonic Motor

A low voltage drive linear ultrasonic motor with a semi-oval shaped stator is proposed in this paper. In the stator, two multilayer piezoelectric actuators are clamped in the holder of the stator by pre-stressing to excite a semi-oval ring. The semi-oval shaped stator is designed to have normal vibration and tangential vibration modes, thus these two orthogonal mechanical vibration modes of the stator can be excited to generate elliptical motion at the contact point of the stator. In design of the motor, ANSYS finite element analysis software was used in this study to accomplish the design and analysis. A prototype motor was fabricated and measured. For single phase signal driving, typical output of the prototype is a no-load speed of 88 mm/s and maximum thrust force of 1.96 N at a voltage of 16 Vp. For two sine wave signals driving, typical output of the prototype is a no-load speed of 106 mm/s and maximum thrust force of 3.33 N at a voltage of 16 Vp.