Precise position control of ultrasonic motor using fuzzy control

The ultrasonic motor has a heavy nonlinearity and time-varying characteristics, which vary with driving conditions. Besides, it possesses variable dead-zone in the control input, which are problems as an accurate positioning actuator for industrial applications. Therefore, it is important to compensate the nonlinearity and time-varying characteristic and eliminate the dead-zone in order to improve the control performance. A precise position control scheme for ultrasonic motor using fuzzy controller with dead-zone compensation to control the phase difference of the driving voltages is presented in this paper. The principle and construction of the fuzzy controller is analyzed, and the design method is proposed.