A Table-Tennis Robot Control Strategy for Returning High-Speed Spinning Ball

Abstract

Table-tennis robots still have a long way to defeat human players because of the rapid decrease in control accuracy when the ball flying speed and spin velocity increase. In this case, the challenge is to control the robot accurately within a limited time. To overcome this challenge, this article introduces a receding horizon optimization method to solve the accuracy problem of spin estimation. With the help of accurate spin information, a single-parameter-optimization-based stroke approach is developed for the robot to guarantee accuracy and efficiency simultaneously. In terms of accuracy, the proposed method achieves the best performance compared with other spin estimation algorithms, and it also achieves a stroke error of 25.13 cm and 23.93 cm for topspinning and backspinning balls, with the passing-net height error being 12.27 cm and 10.57 cm, respectively. Due to the high efficiency of the method proposed, our robot can hit a ball that has a speed of up to 10 m/s, which is a new record for the maximum ball speed that a table-tennis robot can handle to the best of our knowledge. Using the method proposed in this article achieves success rates of 90.0 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$%$</tex-math></inline-formula> and 85.0 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$%$</tex-math></inline-formula> for striking topspin and backspin balls, surpassing the respective success rates of 40.0 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$%$</tex-math></inline-formula> and 13.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$%$</tex-math></inline-formula> obtained by using the previous method.