Dead-Zone Compensation of an Ultrasonic Motor Using an Adaptive Dither

This paper presents a high-efficiency compensation method of the dead zone with the aid of the adaptive dither for the ultrasonic motor. Prior to proposing the method, the influence of the dither on the principal elements of the dead zone, i.e., the deviations of the control variable and the minimum velocity, is analyzed. Then, the improved generation method of the adaptive dither is proposed, which introduces the adaptive dither by orthogonally adjusting the amplitudes of the applied voltages instead of changing the phase difference, as mentioned in the existing studies. Experimental measurements have demonstrated that the proposed method not only can effectively compensate the dead zone and conveniently control the velocity, but also is superior to the existing phase-difference-based method in terms of improving the efficiency of the ultrasonic motor.