Study On Fuzzy Adaptive Speed Control Of Ultrasonic Motor

Nowadays, the research on motion control strategy of ultrasonic motor gets moreand more attention. Designing appropriate control strategy, improving the precision,efficiency and reliability of the motion control system, become the emphases in thestudy of ultrasonic motor.The model of ultrasonic motor system is the foundation of analyzing ultrasonicmotor’s performance, and is also an important premise of designing motor speedcontroller. As the limitations of theoretical modeling, control modeling usually adoptsidentification method based on the tested data. Fuzzy model based on fuzzy reasoningcan describe the nonlinear information, and is easy to make use of people’s relevantexperience knowledge. The complexity of fuzzy model is relatively low. Based onidentification method, this paper works out the appropriate fuzzy modeling method toobtain the dynamic model of ultrasonic motor system. And so, another effective way isproposed for the modeling of ultrasonic motor system.In order to improve the precision of model, the parameters of membershipfunctions on T-S dynamic fuzzy model are optimized by ant colony algorithm.Comparison between tested data and calculated data of the model shows that, the modelcan well simulate the nonlinear relationship among the amplitude of driving voltage,frequency and rotating speed.Fuzzy adaptive controller for speed control of ultrasonic motor is designed usingthe above T-S dynamic fuzzy model. Rules of the fuzzy controller are optimized offlineusing ant colony optimization, and the appropriate parameters of fuzzy controller arealso ascertained during the process of optimization. According to the difference betweenthe responses with different speed values, a kind of online tuning method is proposed tomodulate the proportional coefficient. Experiments indicate that the adjusting time ofspeed step-response is short, and the value of stable error is small. The control result issatisfying.