Stability Of The Traveling Wave Type Ultrasonic Motor And Control Strategy

Ultrasonic motor is a new type of motor developed from the converse piezoelectriceffect of piezoelectric ceramics in the nineteen eighties. It is different from thetraditional electromagnetic motor. Ultrasonic motor has many advantages such as noelectromagnetic interference, low speed and high torque, power self-locking, highdesign degrees of freedom. But ultrasonic motor has nonlinear and strong couplingshortcomings that have also brought a lot of difficulties to motor control. So the stabilityand control strategy have been the hot field of ultrasonic motor control research.The stability of the traveling wave type ultrasonic motor and control strategies aremainly divided into three areas in this paper.①The stability of traveling wave type ultrasonic motor has been studied usingLyapunov stability criterion. The position of ultrasonic motor driving and brakinginterval are clearly divided. Further, the relationships among the three parameters of thepressure, ultrasonic motor load and speed is discussed based on the Lyapunov stabilitycriterion. It provides some references for the design of traveling wave type ultrasonicmotor.②The effect analysis of the traditional control strategy of traveling wave typeultrasonic motor control have been researched with two different control methods, oneis the fixed gain of PI control and another is fuzzy PI control. Two performance indexes(the maximum overshoot and the start time of the motor) were used to compare theeffect of two control strategies. Finally, the principles of the parameter setting on thetwo control strategies of the motor were obtained according to the specific TRUM-60simulation experiments.③The fixed gain PI control and fuzzy PI control are too dependent on theoperating and control experience of the ultrasonic motor. So the generalized predictiveadaptive control (GPAC) using least squares method for ultrasonic motor control objectwas improved. GPAC is identified by the least square method parameters of CARIMAprediction model. The prediction output is calculated according to the input-outputvalue and then through the multi-step Diophantine iterative. Finlly, the prediction outputhas been applied by the driving circuit. It shows good control performance androbustness. In the fifth chapter of this paper, the GPAC principle and improvements onthe traveling wave type ultrasonic motor were introduced. The improved control effect were validated and discussed, and the basic principles of the parameter setting areobtained. The simulation experiments results show that the improved GPAC controlstragety provides a good reference in actual application of the ultrasonic motor.