The Design Theory And Control Of The Cylindrical Ultrasonic Motor

The cylindrical ultrasonic motor is a new type motor that has been developed in recent twenty years. It has the higher torque per volume and the better controllability compared with other kinds of ultrasonic motors. It has been adapted to optical, medical especially the aeronautics and astronautics fields. The researches of cylindrical ultrasonic motor are focused on the developments of the high torque, high precision and quality stability in recent years. So several technical matters such as the force transferring model, the design and optimization of the structure, the drive and control of the motor, and the manufacture technology should be studied deeply and roundly. The research work and method of this thesis are as follows:Based on the representation of the history of ultrasonic motor and combined with the research progress and the application of the cylindrical ultrasonic motor at home and abroad, the problems that have to be solved in this research are discussed.The single-point and the double-point contact modes are discovered and the force transferring model was put forward, on the foundation of the structure and working principle of the cylindrical ultrasonic motor with bending vibration mode. The performance of this motor is analyzed around a critical point of the pre-pressure. AΦ14mm prototype was fabricated. Its maximum torque is 0.11N·m, the no-load speed is about 300r/min.The analytical model of a cylindrical shell is established and solved. The radial and torsional vibrations of this shell are analyzed accurately. It's the basic research to the new type motor.A new radial-torsional vibration hybrid type ultrasonic motor (abbr. RTUSM) is put forward, which utilizes longitudinal vibration derived from radial vibration by Poisson effect. The hollow and short cylindrical structure is easy to make resonant frequencies of first-order radial and torsional vibrations into degeneracy. The FEM method is used to optimize the motor geometry from the stator, rotor, PZT ceramics and friction material. The process flow and requirements are generalize to guide the fabrication of this motor. AΦ60mm prototype is fabricated, and the mechanical characteristics is tested in order to determine the best work and performance parameters. The no-load speed and maximum torque of the motor are 25r/min and 5N·m, respectively.The driving system of the RTUSM is designed, according to its requirements, which considers the key input and LCD display. The driver can adjust the frequency, voltage and phase difference in real time.A high-performance test control system of RTUSM is developed,which is based on the DSP. Through the test of steady-state and transient-state characteristics of the motor, its output performance can be studied in the condition of different driving frequency, voltage and phase difference. In the speed control, the fuzzy proportion control can be selected to adjust the driver frequency to realize the steady rotation in low speed. In the position control, the position/speed dual closed loop control system is studied and designed.