The Ergonomic Design of Wearable Robot Based on the Shoulder Kinematic Analysis by Walking Speed

Abstract

The purpose of this study was to suggest the design of wearable robots based on the shoulder kinematics including the range of motion, angular velocity, and angular acceleration during walking. A treadmill system was used to measure the kinematics data of the shoulder joint during different walking speed. The independent variables of this study were walking speed. Walking speed was set as four levels including 3.6, 5.4, 7.2, and preferred walking speed (PWS) km/h. The subject walked according to the randomized walking speed during 90 s on the treadmill. Twenty gait cycles of motion capture data from each experimental condition of each subject were extracted. Data was analyzed by one-way repeated measures analysis of variance. There were significant differences of minimum joint angle, mean of ROM, maximum joint angular velocity, minimum joint angular velocity, maximum joint angular acceleration and minimum joint angular acceleration. There was no significant difference of maximum joint angle. The kinematics data of ROM, angular velocity, and angular acceleration revealed an increasing trend up to walking speed of 7.2 km/h. It indicates that the arm swinging was sufficiently performed to maintain the walking stability. The maximum angular acceleration increased as the walking speed increased, which meant the instantaneous velocity of the shoulder joint increased. It indicated that the load of the shoulder joint increased with the increase of the walking speed. Hence, this study suggests that the ergonomic threshold for walking speed of the wearable robot could be limited to 5.4 km/h.