Towards a wearable device for skill assessment and skill acquisition of a tennis player during the first serve

Abstract

In this article, the possibility of using wearable gyroscope sensors for skill assessment and skill acquisition was investigated. Marker-based methods were used initially to capture the fast rotational motions and simulate the outputs of gyroscope sensors. Utilizing the marker-based methods, the angular velocity of the upper arm internal rotation, wrist flexion, and shoulder rotation were calculated for a range of athletes using the trajectory of Vicon markers with respect to the Plug-in Gait model during the first serve in tennis. Participants from amateur to elite participated in this study. Thirty successful serves from each participant were assessed. The results showed that the peak values of the upper arm internal rotation, wrist flexion, and shoulder rotation just before impact are indicative in classifying the participants' skill level. It was shown that all the three parameters, as well as the racquet head speed, increased as the level of proficiency of the participants increased. A line (R²=0.89) was fitted to the scatter data containing the upper arm internal rotation, wrist flexion, and racquet head speed. The fit line is a function of upper arm rotation and wrist flexion. The fit line can be used as a potential skill acquisition tool to provide feedback on which variables (upper arm internal rotation, wrist flexion, or shoulder rotation) need to be improved. The positions of three gyroscope sensors to detect the same trends as those from the marker-based methods were determined. Therefore, it is envisaged that gyroscope sensors could be used for skill assessment and skill acquisition for a first tennis serve. © 2010 John Wiley and Sons Asia Pte Ltd