Simple calculation of joint moment for lower extremity during sit to stand motion

Abstract

Muscular strength of elderly people decreased when they get older. Decreased muscular strength made decrease in quality of life of the elderly. Therefore, muscular evaluation was needed. Maximum joint moment during sit to stand could be evaluation method to maximum muscular strength to do activities of daily lives of elderly. Existed system to measure joint moments during sit to stand motion was not clinically friendly. Therefore, goal of the study was to make simplified system to measure joint moment during sit to stand motion. To make simplified system, simplified equation which joint position and ground reaction force was used to decrease sensors to detect kinematic components. Joint position during sit to stand was estimated based on the sitting posture. Shank angle displacement during sit to stand was measured by IMU to add sitting shank angle. Thigh angle was estimated by relationship between thigh segment and edge of chair. Joint moment for lower extremity was calculated by estimated segment angle. To see accuracy, joint moment from propsoed system was compared with joint moment from Mocap.. Most of maximum lower extremity joint moment error was less than the 20% in symmetric and asymmetric sit to stand. Also correlation coefficient was over 0.95. For the future research, method to estimated segment angle needed to be modified to increase accuracy and validation to the elderly. ⓒ 2017 DGIST