Validation of UWB positioning systems for player tracking in tennis

Precise and reliably tracking of players’ position during the action or during the game is important in many sports. Our motivation was to investigate and validate the use of ultra-wideband (UWB) systems for various player and coach applications that depend on tracking the position of the player and possible related events. We developed and implemented a real-time positioning system that allows (a) the validation of UWB positioning and (b) a test application to support tennis game strategy, which monitors the trajectory of players and analyzes their position frequency in different tennis court areas at the moment of ball impact. The accuracy of the UWB positioning system is verified by the professional high-precision optical tracking system Qualisys. The validation of our UWB system, which operates in a dynamic mode in open space, was performed at distances between the devices in the range of 4.7 to 14.9 m. The measured distance errors between the tag and two anchors show mean values of 0.1 cm and 1.8 cm and variances of 14.9 cm and 14.3 cm. The absolute position errors on the tennis court have mean values of 14.2 cm and a variance of 16.1 cm. The position error limits for the confidence intervals of 50%, 90%, and 95% are 10.2 cm, 25.6 cm, and 33.4 cm, respectively. The developed application helps trainers to organize and perform training exercises by providing accurate analysis results that are otherwise very difficult to obtain. At impact, the absolute position error is slightly smaller due to the lower speed of the player; the average measured position error at impact is therefore 11.3 cm. The results of the field tests confirm the usability of the UWB system for position tracking in tennis, as well as in other similar sports applications. © 2020, Springer-Verlag London Ltd., part of Springer Nature.