A Novel Inexpensive Camera-Based Photoelectric Barrier System for Accurate Flying Sprint Time Measurement

Abstract

This paper introduces a novel approach to addressing the challenge of accurately timing short distance runs, a critical aspect in the assessment of athletic performance. Electronic photoelectric barriers, although recognized for their dependability and accuracy, have remained largely inaccessible to non-professional athletes and smaller sport clubs due to their high costs. A comprehensive review of existing timing systems reveals that claimed accuracies beyond 30 ms lack experimental validation across most available systems. To bridge this gap, a mobile, camera-based timing system is proposed, capitalizing on consumer-grade electronics and smartphones to provide an affordable and easily accessible alternative. By leveraging readily available hardware components, the construction of the proposed system is detailed, ensuring its cost-effectiveness and simplicity. Experiments involving track and field athletes demonstrate the proficiency of the proposed system in accurately timing short distance sprints. Comparative assessments against a professional photoelectric cells timing system reveal a remarkable accuracy of 62 ms, firmly establishing the reliability and effectiveness of the proposed system. This finding places the camera-based approach on par with existing commercial systems, thereby offering non-professional athletes and smaller sport clubs an affordable means to achieve accurate timing. In an effort to foster further research and development, open access to the device's schematics and software is provided. This accessibility encourages collaboration and innovation in the pursuit of enhanced performance assessment tools for athletes.

Keywords: mobile device; photoelectric barriers; sports performance measurement; sprint time measurement.

Figure 1

Camera footage with the detection area shown in black and the white areas marking regions, where the image-to-image error is actually calculated. Left: Full virtual barrier. Middle: Default virtual barrier in white. Right: Multi-barrier setting.

Figure 2

The left image of this figure shows the schematics for one photoelectric barrier. The RGB diode is used to show the status of the device and the voltage divider is used to measure the battery charge. The right image shows a screenshot of the control app (German version), which displays important parameters of the hardware and the recorded trials. Our app is compatible with all Android smartphones and tablets version 5.0 and above that have Bluetooth capabilities.

Figure 3

Our camera-based photoelectric barrier can be easily placed on a tripod. Unlike traditional systems, no reflector is required, which greatly reduces setup time. Bluetooth communication eliminates the need for wires.

Figure 4

Bland-Altman plots of the two experiments performed. Almost all measurement points are within the 95% limits of agreement, which shows that the proposed system has similar accuracy to a professional photoelectric barrier system.