Position control of ultrasonic motors using adaptive backstepping control and dead-zone compensation with fuzzy inference

The ultrasonic motor has a nonlinearity, which varies with the driving conditions and possesses variable dead-zone in the control input that is associated with the applied load torque. The dead-zone is a problem in accurate positioning for actuators. To improve the control performance of the ultrasonic motor the dead-zone nonlinearity should be eliminated. This paper proposes a new position control scheme for the ultrasonic motors, that eliminates the problem due to dead-zone by employing the backstepping control with fuzzy inference. The dead-zone is compensated by fuzzy inference, and the adaptive backstepping control performs accurate positioning of the drive system. Experimental results are given to validate the proposed scheme.