Application of IMU-based Motion Measurement Methods to Table Tennis Coaching

(Service stroke measurement experiments)

Abstract

We aim to develop a method to measure a table tennis service stroke using an inertial measurement unit (IMU). In table tennis coaching, the orientation of the racket face and the velocity of the racket in a stroke is considered to be important. The mainstream approach to giving real-time technical skills instructions is to have athletes gain technical senses and knacks by having them observe model movements and giving appropriate advice from the coach. It is expected that the quality of on-site coaching can be increased by adding numerical data that serves as objective indicators to back those instructions. However, quantitative data of the racket is usually unavailable in field without using expensive motion capture systems. IMU-based motion estimation methods can enable cheap and handy table tennis stroke measurement. In this paper, we discuss how such methods can be applied to table tennis and we propose a method to measure a service stroke. Accumulated errors in IMU data integration are corrected using a constraint of predefined initial and final states. We measured six types of service strokes 10 times each. The estimated racket trajectories exhibited practical accuracy for the purpose of table tennis coaching.