210 The measurement method of the wrist joint angle during tennis racket swing

Abstract

As topspin has been becoming a vital component for modern-day tennis, precise researches of friction between the string-bed and ball were carried out. However, from another viewpoint, it is necessary to clarify the relation between the grip angle and topspin in order to acquire the technique quickly or to prevent the wrist injury that occurs by taking a swing of topspin. The aim of this research is to make the measuring system that acquires the angle of wrist joint during the racket swing of topspin. In order to measure hand and forearm posture in inertial frame of reference during racket swing, two inertial sensors were attached to the back of hand and forearm. The angular velocity and acceleration were acquired from these sensors, and from the data, Euler angles were calculated in three-dimensions. From these Euler angles, the wrist angle was computed, and the difference of wrist angle during the swing between the Western grip and the Eastern grip was compared. These results showed that this measuring method expressed the characteristic of topspin precisely.