A Novel Ball-Racket Rebound Model for Table Tennis Robot Based on Continuous Contact Force

In table tennis, developing a precise ball-racket rebound model is crucial for predicting the trajectory and spin of a ball after it hits the racket, which is instrumental in racket design and enhancing the capabilities of table tennis robots. To this end, accuracy and computational efficiency are two challenges to overcome, which has not been perfectly handled using existing methods such as finite element (FE) and simplified rigid-body models. This article introduces a new model that calculates ball-racket rebounds in two orthogonal directions. Vertically, the collision dynamics are analyzed with the Kelvin-Voigt model, revealing that the contact duration is independent of the incoming ball's velocity. Horizontally, we establish that the restitution coefficient varies as a function of the incident velocity, based on a continuous contact force model and momentum conservation principles. High-speed camera data corroborate these findings and confirm the model's efficacy across diverse conditions. Compared to an established representative model, our method not only maintains high computational efficiency but also improves the accuracy of predicting the ball's linear and angular velocities by an average of 42.72% and 33.77%, respectively, as evidenced by our experimental data.