Quick and Precise Position Control of Ultrasonic Motors With Two Control Inputs

Abstract

Ultrasonic motor (USM) has an excellent. performance and many useful features. Since this motor is superior in holding torque and high response characteristic. it has been expected to use as position servomotor for small motors.There have been reported some mathematical models of the ultrasonic motor. however, t.hese models are too complex to apply for control of the motor. Therefore posit.ion controllers based on PI control or fuzzy control haw lx-eu proposed in recent. years. It is difficult to control the ultrasonic motor with high-performanrrusing such controllers, thus simple and convenient mathematicalmodcl is necessary for precise control, This paper presents a new position control scheme of ultrasonic motor. it consists of a PI controller and an adaptive controller which compensates the speed characteristic variations with online parameter identification. Moreover. this svstem controls both driving frequency and phase difference in order to achieve a quick and precise position control. The effectiveness of proposed courrol scheme is demonstrated by experiments.

Velocity Control of Traveling-Wave Ultrasonic Motors Based on Stator Vibration Amplitude

“…A TWUSM is driven by the two-phase sinusoidal waves, which excite elliptical motion on the stator [6,7]. Generally, the velocity of TWUSMs is controlled by the voltage amplitude [8], the driving frequency [9,10,11,12,13], or the phase difference between the two-phase sinusoidal waves [14]. However, the resonance frequency may drift significantly when the operating conditions change [1].…”