Dynamics of a bouncing table tennis ball from the acoustic signature using an optical fibre sensor

Abstract

We describe an optical fibre-based method to estimate impact force and collision duration using time measurements recorded from acoustic signals of a table tennis ball bouncing on a table. The technique combines measurements obtained from a polarisation dependent optical fibre sensor with graphical analysis and kinetics through numerical calculations. The presented coefficient of restitution (COR), collision time, impact force, and elastic deformation during each bounce of the table tennis ball were obtained using corresponding time series measurements and numerical analysis. A peak impact force of 38.4 N was estimated for a ball of mass 2.83 g and 39.7 mm diameter dropped from a height of 31.5 cm. The impact duration for the associated bounce was 0.68 ms with a centre of gravity shift of 0.40 mm and COR of 0.88. While the observed results are unique to the ball and table surface, the approach is an attempt to fully quantify collision parameters from basic measurement and instrumentation applicable to undergraduate students. The sensor developed in this paper finds application in sports performance monitoring, infrastructural health early warning systems and pressure sensitive manufacturing processes.