Verification of the accuracy and reliability of the TrackMan tennis radar

Abstract

TrackMan, a device used to measure the kinematics of a ball in flight, has recently been used for research and coaching purposes in tennis, and the number of studies on this device is expected to increase. This study is focused on verifying the accuracy of TrackMan; three participants performed services with various velocities and angular velocity combinations. TrackMan and a proven method based on computer vision were used to measure the speed, spin rate, and spin axis of the ball. The results obtained using each method were compared using regression analysis, intraclass correlation coefficients, and Bland–Altman analysis. The speed and spin rate of the two methods agreed well; the degree of error would not be problematic in practical applications. However, TrackMan underestimated the speed if it was unable to detect the hitting position. The spin axis measured by TrackMan was unstable under low spin rate conditions (<3000 rpm). Furthermore, the standard deviation of the spin axis measurement error exceeded the difference between the average slice and kick service spin axes reported in the previous study, so the spin axis measurement accuracy was very low for research purposes, even when the spin rate was above 3000 rpm. For those who are aware of the existence of outliers, TrackMan can be useful for coaching because it provides instant feedback. Similarly, the measured rotational speed and spin rate could be used in the study.

The relationship between service performance and physical strength focusing on speed and spin rate in Japanese elite junior tennis players

“…If a ball in flight reflects a radio wave, the frequency of the reflected wave shifts, depending on the velocity and spin of the ball, and is calculated by a dedicated software (Martin, 2012). Doppler effect-based measurement devices are superior to other devices in terms of immediacy and user-friendliness and are used in golf coaching and baseball (Murata and Takahashi, 2020). The accuracy of the TrackMan system is equivalent to that of conventional high-speed cameras or speed radar devices, as reported in recent studies (Martin, 2012;Murakami et al, 2016;Murata and Takahashi, 2020;Sato et al, 2017).…”

“…This device is an advanced radar that utilizes the Doppler effect to capture the behavior of an object; in this case, the full three-dimensional flight of a tennis ball (speed, spin, spin axis). The Doppler effect is a phenomenon in which the relative velocity between a generation source and an observer result in the shifting of sound or radio wave frequencies (Murata and Takahashi, 2020). If a ball in flight reflects a radio wave, the frequency of the reflected wave shifts, depending on the velocity and spin of the ball, and is calculated by a dedicated software (Martin, 2012).…”

Prediction of Service Performance Based on Physical Strength in Elite Junior Tennis Players

“…In this case, the full three-dimensional flight of a tennis ball (speed, spin, spin axis) was recorded. The Doppler effect is an effect in which the relative velocity between a source and an observer results in the shifting of sound or radio wave frequencies ( Murata and Takahashi, 2021 ). If a ball in flight reflects a radio wave, the frequency of the reflected wave shifts, depending on the velocity and spin of the ball, and is calculated using the dedicated software ( Martin, 2012 ).…”

“…If a ball in flight reflects a radio wave, the frequency of the reflected wave shifts, depending on the velocity and spin of the ball, and is calculated using the dedicated software ( Martin, 2012 ). Doppler effect-based measurement devices are superior to other devices in terms of immediacy and user-friendliness and are often used in golf coaching and baseball ( Murata and Takahashi, 2021 ). The accuracy of the TrackMan system is equivalent to that of conventional high-speed cameras or speed radar devices ( Martin, 2012 ; Murakami et al, 2016 ; Sato et al, 2017 ; Murata and Takahashi, 2021 ).…”

“…Doppler effect-based measurement devices are superior to other devices in terms of immediacy and user-friendliness and are often used in golf coaching and baseball ( Murata and Takahashi, 2021 ). The accuracy of the TrackMan system is equivalent to that of conventional high-speed cameras or speed radar devices ( Martin, 2012 ; Murakami et al, 2016 ; Sato et al, 2017 ; Murata and Takahashi, 2021 ). This allows for real-time measurements and analysis of parameters, such as spin rate, speed, direction, impact location (height and depth), net clearance, and landing position.…”