Rotary ultrasonic motor driven by a disk-shaped ultrasonic actuator

A rotary ultrasonic motor, including a disk-shaped ultrasonic actuator and a rotor, is developed, and the characteristics of the motor, including speeds, torques, output powers, and efficiencies, against various preload forces, voltages, and frequencies are investigated. The actuator is developed on a thin piezoelectric buzzer with three fixed screws and driven by a single-phase electrical power source. Here, the buzzer is composed of a nickel-alloy disk and a piezoceramic disk, and the screws are individually arranged at 90°, 120°, and 150° arc locations on the nickel-alloy disk. An optimal driving point of the actuator for driving the rotor in both clockwise (CW) and counterclockwise (CCW) directions is located at a point on the 90° arc edge region, and the CW and CCW directions are controlled by the frequency of the electrical power source. In doing so, the principle, construction, and driving mechanism of the actuator are first expressed. Then, the principle is verified according to vibration mode analysis with ANSYS simulation. The ANSYS simulation concerns the numerical model, structure, and mesh analysis as well. Moreover, a driving and measuring system, including an ac power supply system and a system that measures speed and twist forces, is constructed to evaluate the performance of the actuator and motor.