It is important to analyze the patterns of course distribution of ball objectively as tactics in table tennis competition, especially to obtain the results instantaneously. However, developing a system to analyze such patterns in real time is very difficult because the pitch of the table tennis rally is quite fast. In addition, in order to analyze the distribution pattern, it is necessary to measure the place where the ball bounces on the table. The accuracy of measurement is also important. In this research, we focused on the fact that the collision sound of the table tennis ball has high frequency. We tried to detect the collision sound using plural ultrasonic sound sensors and estimate the coordinates of the falling point from the difference of the propagation time of the sound wave in real time. We examined this method in the present work. In order to cover the whole table tennis table, the ultrasonic sound sensor units were set up at three points near the net on each side of the net. The total of units was 6. The sound wave signal transmitted from each sensor shows the difference in arrival time. This difference was processed by a comparator in multichannel counter, and the falling point was calculated by the trilateration method with CPU in multichannel counter. In this way, we have developed a system to estimate the coordinate position. The result of dropping the ball to 40 known coordinate points shows that the error with the calculated coordinates was 1.68±1.94cm in the x direction, and 11.04±4.98 cm in the y direction. It is found from this that the coordinates of falling point of the ball can be estimated with sufficient accuracy, and that the system developed in this work serves the analysis of the ball delivery pattern.
© Copyright 2017 Proceedings Book of The 15th ITTF Sports Science Congress Düsseldorf, 27th - 28th May 2017. Veröffentlicht von International Table Tennis Federation. Alle Rechte vorbehalten.