Table Tennis Ball High-speed Spin Measurement System Using M-sequence Multi-exposures and Symmetric Dot Markers

Summary

Table tennis is a ball game sport characterized by spin. Spin, which is said to reach up to 150 rps, is an important tactical element because it significantly changes the trajectory of the ball, and real-time measurement of high-speed spin is expected to be used to improve play and to develop table tennis robots. However, spin of 150 rps causes about 54 degrees of rotation per frame even with a high-speed camera at 1,000 fps, so even with a 1ms Auto Pan-Tilt system, which enables continuous observation of the high-speed translational motion of the table tennis ball, it is not easy to measure spin due to motion blur of the rotational motion.

In this study, we propose a system to instantly measure the high-speed spin of the table tennis ball by drawing symmetric dot markers on the ball surface and capturing multi-exposure images in a single frame with M-sequence codes (Fig. 1). The motion blur of the dot markers due to spin is captured as dashed lines by the M-sequence multi-exposures (Fig. 2), and the spin of the table tennis ball is estimated quickly and accurately by solving a posture estimation problem for each captured frame (Fig. 3). High-resolution imaging using the 1ms Auto Pan-Tilt system enables measurement of the spin of the table tennis ball during its large translational motion (Fig. 4). This system enables instantaneous measurement of table tennis ball spin information during a rally, and is expected to be applied in sports fields such as table tennis play improvement through immediate visual information feedback combined with a high-speed projector, and the development of table tennis robots that can quickly respond to the amount and direction of spin.

Fig. 1 System configuration.	Fig. 2 M-sequence multi-exposures.
Fig. 3 Multi-exposure simulation image.	Fig. 4 High-speed spin image in optical tracking.

Reference

1. Tomohiro Sueishi, Himari Tochioka, and Masatoshi Ishikawa: High-speed Spin Measurement System for Dotted Table Tennis Ball Using Single-frame M-sequence Multi-exposures, SICE Journal of Control, Measurement, and System Integration, Vol. 18, Issue 1, pp.1-11 (2025)
2. Tomohiro Sueishi, Himari Tochioka, and Masatoshi Ishikawa: High-speed Spin Measurement Method for Dotted Table Tennis Ball Using Structured Light of M-sequence Flickering Pattern, SICE Festival 2024 with Annual Conference (SICE FES 2024) (Kochi, 2024.8.30)/Proceedings, pp.1188-1193