Locating Tennis Ball Impact on the Racket in Real Time Using an Event Camera

TL;DR

This paper introduces a real-time method using event cameras to locate tennis ball impacts on rackets, overcoming high-speed camera limitations and enabling continuous performance monitoring.

Contribution

The paper presents a novel event-camera-based approach for real-time impact detection in tennis, reducing memory use and manual effort compared to traditional high-speed cameras.

Findings

Accurate impact location detection within permissible performance range

Real-time processing with short computation time

Effective continuous monitoring over extended periods

Abstract

In racket sports, such as tennis, locating the ball's position at impact is important in clarifying player and equipment characteristics, thereby aiding in personalized equipment design. High-speed cameras are used to measure the impact location; however, their excessive memory consumption limits prolonged scene capture, and manual digitization for position detection is time-consuming and prone to human error. These limitations make it difficult to effectively capture the entire playing scene, hindering the ability to analyze the player's performance. We propose a method for locating the tennis ball impact on the racket in real time using an event camera. Event cameras efficiently measure brightness changes (called `events') with microsecond accuracy under high-speed motion while using lower memory consumption. These cameras enable users to continuously monitor their performance over extended periods. Our method consists of three identification steps: time range of swing, timing at impact, and contours of ball and racket. Conventional computer vision techniques are utilized along with an original event-based processing to detect the timing at impact (PATS: the amount of polarity asymmetry in time symmetry). The results of the experiments were within the permissible range for measuring tennis players' performance. Moreover, the computation time was sufficiently short for real-time applications.