Ball-Spin Control and Vibration Reduction Methods for Three-Wheel Pitching Device of Tennis Training Robot

A novel three-wheel tennis pitching device for tennis training robots is designed, which features pitching tennis balls with various self-spins. The device is composed of aluminous hubs, rubber tyres, and high-speed brushless motors. Besides, a ball-spin control method is implemented to pitch balls with target self-spins, which is based on the combined effects of three pitching wheels rotating at different speeds. In view of the device’s vibration caused by high-speed rotors, a vibration reduction method applicable to pitching wheels is proposed through correcting the position of the center of mass. The method weakens vibration easily with twice drilling operations. Furthermore, simulations and experiments are conducted to validate the effectiveness of the proposed methods.