Low-cost system for real-time detection of the ball-table impact position on ping-pong table

Acoustic signal processing method can be used to estimate the impact source position generated on ping-pong table. The source position is often determined by the time differences of arrival (TDOA) of a signal received at a number of sensors. This paper presents a low-cost system for detecting ball-table impact positions on ping-pong table in real-time. Based on the principle of stethoscope, the designed sensors were placed below the table to minimize the influence of external noise. Also, the onset time of an impact signal is detected by using dynamic thresholds based on the Six-Sigma limit, and frequency-band-energy (FBE) ratios. The position of an impact source is determined by a new algorithm to detect the impact area where the impact signal was generated and is displayed on a computer or mobile phone via Bluetooth communication. The experiment results show that the positioning accuracies are all higher than 94% even up to 100% which can provide useful information during table-tennis trainings and games.