Robust Speed Control of Ultrasonic Motors via Gain-Scheduled H_∞ Control on Stator Vibration Amplitude

Abstract

This paper deals with a controller synthesis problem for precise speed control systems of ultrasonic motors (USMs) considering nonlinear characteristics of USMs. For this problem, we firstly propose a parameter varying plant model which represents the nonlinear characteristics by using information of amplitude of stator vibration as a model parameters. Secondly, to provide higher performance for the systems, we design a parameter varying controller in a systematic way by applying gain-scheduled H_∞ control technique for the parameter varying plant model. In addition, control experiments show the validity of the proposed method.