On-line identification method of static friction for ultra-precision positioning

This paper presents a friction model-based ultra-precision stage control that utilizes the contact-type non-resonant ultrasonic motor. At first, the friction characteristic is experimentally evaluated as a function of the stage position. Next, focusing on the non-linear property of the static friction, the model-based control system is constructed. The authors also consider the time variation of the static friction, the on-line identification method is proposed. Finally, the efficiency of the friction identification and compensation methods is verified through the positioning experiments.