An effective frequency tracking control and balancing compensation between CW & CCW rotation speed techniques for ultrasonic motor

The relationship between the rotation speed of an ultrasonic motor and its driving frequency behaves nonlinearly with time-variability. Furthermore, the performances of the USM when rotating clockwise (CW) and counter-clockwise (CCW) are inconsistent. As a result, the practical applications of USM are limited. We present research on speed control techniques for a traveling-wave-type ultrasonic motor, and, aimed at the losing balance between the CW and CCW rotation speed, a balancing compensation algorithm is put forward. Experimental results show that, after combining the speed controller and balancing compensation controller in the driver, the speed of the USM possesses linearity and time-invariability with the command voltage, and the CW rotation speed of the USM has a better accordance with the CCW speed.