Position Control for Ultrasonic Motors Using Backstepping Control and Dead-Zone Compensation with Fuzzy Inference

Abstract

The ultrasonic motor has a heavy nonlinearity, which varies with driving conditions and possesses variable dead-zone in the control input associated with applied load torque. The dead-zone is a problem as an accurate positioning actuator for industrial applications and it is important to eliminate the dead-zone in order to improve the control performance. This paper proposes a new position control scheme of ultrasonic motors to overcome dead-zone employing model reference adaptive control (MRAC) with fuzzy inference. The dead-zone is compensated by fuzzy inference, and backstepping control performs accurate position control. As compared with MRAC which uses an augmented error, backstepping control can analyze a transient response. Mathematical models are formulated and experimental results are given to validate the proposed position control scheme. © 2003, The Institute of Electrical Engineers of Japan. All rights reserved.