Study On Fuzzy Speed Control Of Ultrasonic Motor

The running mechanism of ultrasonic motor is different from the traditionalelectromagnetic motor, it makes the ultrasonic motor has some unique advantages inits application. But at the same time it makes the ultrasonic motor have strongernonlinearity and time-varying characteristic. So it is hard to get good controlperformance by using simple control methods.As a kind of intelligent control method, fuzzy control is applied in the motioncontrol of ultrasonic motor in recent years. Fuzzy control is a nonlinear controlstrategy including fuzzy logic reasoning, it is suitable for the control of nonlinearobjects such as ultrasonic motor, and to some extent it has robustness to the variety ofparameters for the motor.In this paper, considering to the operational characteristics of ultrasonic, atraditional fuzzy speed controller is proposed to realize the speed control ofultrasonic motor. In order to make the control performance better, and then anadvanced fuzzy speed controller is proposed based on the traditional one. The scalingfactors of fuzzy controller are adjusted online according to the error of speed and itsatisfies the needs of different scaling factors at different step response. This methodis simple in design and the amount of online calculation is small. The experimentalresults in variety conditions show that, the control effect is good and robustness isstrong.In order to further improve the control performance of the speed fuzzy controllerof ultrasonic motor, the scale factors and rules of the variable parameters fuzzycontroller are optimized offline by using the dynamic particle swarm optimizationalgorithm and chaos particle swarm optimization algorithm. The better optimizationalgorithm is chosen based the comparison results of the two different optimizationalgorithms. And the scale factors are designed adjusting according to different givenspeed based on the experimental date. Experimental results show that, after theoptimization and advance of the fuzzy controller its control effect is better and it has strong robustness.