Optical flow-based closed-loop control of a multi-degree-of-freedom clamping-type ultrasonic motor

Abstract

Rotor speed and position detection are integral parts of the closed-loop control system for multi-degree-of-freedom (multi-DOF) ultrasonic motors. The non-contact speed detection method is important for the high-precision control of the spherical rotor. This paper proposes a closed-loop control method based on an optical flow sensor for the velocity–position control of a multi-DOF clamping-type ultrasonic motor. The optical flow information is analyzed using the conical L–K optical flow algorithm to obtain the rotor speed and position. An incremental PID control method is used to perform dual closed-loop positioning control of the motor regarding speed and position. An experimental platform for the optical flow sensor is designed, and the method’s feasibility is verified experimentally.