Binocular ultra-high-speed photography for measuring tennis ball speed and spin at impact
Year: 2026
Type: article
Abstract: Ball speed and spin at impact characterize tennis stroke quality, yet measuring both on an unmodified ball has required costly trackers or instrumented balls. We developed a synchronized binocular ultra-high-speed photography system recording at 2000 frames per second that reconstructs three-dimensional ball-center trajectories stereoscopically and recovers rotation from the natural seam texture by closed-form quaternion attitude estimation. Across 178 valid strokes from 15 provincial-level players, reconstruction was independently validated to 1.83 mm (static) and 2.34 mm (dynamic) position error, ball speed agreed with radar within 2.02 km/h, and rotational angular velocity matched a gyroscope-instrumented ball (2.87%) and a blinded human-annotation reference (3.05%). Flat, topspin and slice strokes showed distinct speed-spin coupling on the same trials. Costing about RMB 128,000 (≈USD 18,000) and deployable in 4 h, the system offers accessible marker-free stroke diagnosis for research, education, and grassroots coaching, complementing rather than replacing full-court commercial platforms.
Source: iScience
Institution: Capital University of Physical Education and Sports
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,240
OpenAlex ID: W7204907325