RESUMO
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.
RESUMO
This paper proposes a multi-degree-of-freedom (multi-DOF) ultrasonic motor with four stators clamping a spherical rotor. The stator surface teeth are inclined at a certain angle, using the inclined surface to contact the rotor and transfer energy. The motor frame is exquisitely designed in which substrates hold four identical stators to drive the rotor to achieve a multi-DOF rotation. COMSOL Multiphysics performs the stator's modal analysis and harmonic response analysis to illustrate the vibration mode and frequency response. A prototype is fabricated to verify the operating principle and conduct the performance tests. The experimental results indicate that the motor can reach a no-load speed of 100r/min, and the stalling torque is 150mNm under a preload of 113 N. The results also denote the motor has a high load-carrying capacity with a maximum load torque of 143mNm and accurate operation with a maximum error of 0.15 mm.