Development of a motion capture system for swimming by using inertia motion sensors

Abstract

Motion capture systems are used in various fields such as sports, medical, and robotics. Among the motion capture systems, optical systems are used most commonly, and these are also used in the experiments to obtain swimming motion in many studies. However, their own problems such as marker loss and marker misrecognition induce difficulties in experiments especially for swimming motions. In addition, the optical systems are generally very expensive and large scale. The objective of this study was to develop a new motion capture system for swimming by using inertia motion sensors that swimmers can use in a daily training. In this report, the conversion programs to transform the captured data into the form to analyze in SWUM were constructed by considering standard posture, rotating coordinates, and the direction of the model in the world coordinate. An example of conversion was conducted for a motion on the land. From the results of conversion, it was confirmed that the converted motion generally corresponded to the original motion. In addition, sensor parts were waterproofed by using freezer bags, silicon type fillers, and water-resistant adhesive.