Design of a novel ultrasonic motor achieving both single-mode and multi-mode coupling using parallel symmetrical...

This paper proposes an ultrasonic motor capable of achieving both single-mode and multi-mode coupled operation. The stator structure is simple and fully symmetrical, consisting of two parallel sandwich-type vibrators. The motor achieves flexible switching between single-mode and multi-mode coupled operation by selectively exciting the longitudinal vibration modes of the left and right vibrators. Due to the symmetry of the dual-vibrator stator structure, the frequencies of the two coupled modes are naturally close, and improving motor design efficiency. Moreover, this dual-vibrator structure enables the motor to maintain consistent bidirectional output characteristics even when operating in single-mode configuration. Since piezoelectric ceramics operate in the d₃₃ mode with high electromechanical coupling capability, the sandwich structure effectively enhances the output performance of the motor. This thesis first details structure and operating principles of the motor. Subsequently, finite element analysis software is employed to conduct modal analysis, frequency and transient analysis of the stator, validating its feasibility. Finally, a prototype is fabricated and tested on an experimental platform to evaluate its output performance. In single-mode operation, the prototype achieves a maximum speed of 434 mm/s, a maximum load of 0.8 kg, and a maximum efficiency of 5.03 %. In multi-mode coupled drive mode, it achieves a maximum speed of 612 mm/s, a maximum load of 1 kg, and a maximum efficiency of 3.69 %. The motor also achieves a resolution as high as 8.1 nm. The motor features a compact structure and simple drive mechanism, enabling seamless switching between two operating modes. It exhibits relatively favorable output characteristics, making it suitable for various precision drive applications such as optical instruments, medical equipment, and aerospace systems.