Robust Position Control of Ultrasonic Motor Considering Dead-Zone Shogo Odomari1, Araz Darba1, Kosuke Uchida1, Tomonobu Senjyu1, and Atsushi Yona1 1Department of Electrical and Electronics Engineering, University of the Ryukyus, Japan E-mail:
[email protected] Abstract— Intrinsic properties of ultrasonic motor (high torque for low speed, high static torque, compact S1 D1 S3 D3 C L1 USM Load in size, etc.) offer great advantages for industrial ap- 1 Va plications. However, when load torque is applied, dead- E zone occurs in the control input. Therefore, a nonlinear Vb y controller, which considers dead-zone, is adopted for ul- C2 L 2 trasonic motor. The state quantities, such as acceleration, S2 D2 S4 D4 RE speed, and position are needed to apply the nonlinear controller for position control. However, rotary encoder causes quantization errors in the speed information. This − f MOS FET Micro ye paper presents a robust position control method for ultra- driver φ computer sonic motor considering dead-zone. The state variables y for nonlinear controller are estimated by a Variable r e Structure System(VSS) observer. Besides, a small, low Personal cost, and good response nonlinear controller is designed computer by using a micro computer that is essential in embedded system for the developments of industrial equipments. Fig. 1 Drive system of USM. Effectiveness of the proposed method is verified by the experimental results. 150 Va Vb 100 I. INTRODUCTION B V , [V] 50 A In recent years, ultrasonic motor(USM) is gaining V 0 attention as it has good characteristics and is small in size.