Motion analysis of table tennis ball and racket mutual collision

Abstract

Table tennis, a sport that is played widely around the world, and even at the Olympics, is also a recreational sport enjoyed in diverse facilities that can accommodate table tennis tables. Table tennis ball rotation during the game is not well understood because the ball rotation is nearly invisible to observers and players. This study was conducted to elucidate table tennis ball behavior, such as its rotation, that a table tennis player senses through the table tennis racket with eyes, ears, and tactile sense. The rotational and translational motions of balls of various rotations launched from a table tennis machine were assessed using a high-speed camera. After balls with various rotations were made to collide with a racket fixed at 90 degrees to the ground, the racket strain was examined at eight points. A ball with no rotation was free-fallen; it collided with a racket fixed horizontally. Fast Fourier transform analysis was applied to the strain values of the ball impacting the racket tip and the racket center. The kinetic energy values of the ball before and after impact were compared. Findings indicated that the number of rotations of the ball decreased after the struck the racket. When a ball with rotation is struck with the racket, the vibration caused by the grip strain persists for a long time (0.2 s). When the ball has free-fallen in the racket center, the vibration is less than when it has free-fallen at the racket edge area. Players are thought to sense the ball rotation not only with their eyes and ears, but also as tactile information related to the vibration strength of the grip section. The racket vibration shapes differ when a ball strikes the racket center and when it hits the racket edge area. Specifically, less vibration is felt when the ball hits the racket center, thereby enabling the player to return the ball skillfully with high speed, power, high ball rotation, etc.