The Research Of Control System For Ultrasonic Motor

Ultrasonic motor (abbr. USM) is a relatively new type of direct-drive motor. Its operating principle is quite different from the traditional electromagnetic motors. USM utilizes the mechanical vibration in the ultrasonic frequency scale that was generated by the converse piezoelectric effect of piezoelectric ceramics. It has the stator in direct contact with the rotor driven by a friction contact. USM has many excellent performances and features such as high torque at a low speed, compactness in size, high holding torque when power is off, insensitive to magnetic fields, fast response, and no noise and so on. It has more excellent performance than the electromagnetic motor in the field needing compact, efficient, intermittent motion and fine controls. USM has seen commercial application and the attractive prospects in areas such as automobile, office automation, robots, precise positioning device, miniaturized machines, etc. In recent years, USM has attracted considerable attention as a new type of actuator in servo-system and much more researches were carried out.The thesis object is mainly concentrated on the Ring-type Ultrasonic Motors (abbr. RTWUM) and its control principle, a DSP-based control-test system for USM and a speed and position control system of USM are also researched. The contents are summarized as follows:First chapter summarizes the actuality and development of ultrasonic motor, the characteristics and development of the drive and control techniques of USM, especially sets out the virtues and the wide applications of USM. On the basis of above mentioned, the develop direction of control techniques and the content of this thesis are pointed out.On the basis of the analysis of the driving mechanics of USM, second chapter researches the mathematic model and electricity model of USM and presents the driving and control methods and the principle of control system of USM.Base on the principle and driving characteristics of ultrasonic motor, third chapter researches the DSP-based control system of ultrasonic motor, and simply presents the testing system of ultrasonic motor.In the research of driving principle of USM, three control methods are mainly presented which are P-adjusting speed and position control, PID-adjusting speed and position control and fuzzy adaptive PID adjusting speed and position control. Using these three methods to control USM, the control characteristics of USM under these three methods were tested and the results were analyzes. It also presented that different methods are fit for different control objects.