Construction of the Skill Mapping Method of Ukemi for Evaluating the Skill of Protective Motion

Abstract

Fall accident occurs in daily life. But especially in elderly, it leads to serious injury. Therefore the prevention of fall injury is necessary. Previous studies analyzed fall injuries using human body model and finite element analysis, but these studies are related to after-fall phases. Other study evaluated each person's protective motion that is occur during the fall. However, elderly's fall occur because of the decline of the protective motion skill due to the decline of motor function. Therefore to improve each person's motor function, evaluation of protective motion skill is necessary. In this study, we adopt Ukemi (the technique used in Judo) as protective motion and evaluating the skill of Ukemi by comparing Judo expert and beginner. The experiment to measure the Ukemi motion was conducted using motion capture system. The subject were 10 Judo experts and 10 beginners. The motion capture data was inputted to Opensim, a musculoskeletal model, and then converted to joint angle data. To compare the motion, the start and end time of Ukemi is extracted using change point detection method. And then feature of motion is extracted using principal component analysis. As a result, we found that expert's motion is shorter than beginner. Also we found the difference of Ukemi motion between expert and beginner. Further study is needed to evaluate each person's skill more precisely and construct the method to improve protective motion skill.