To locate the center of gravity position, previous studies photographed human body motions and then applied body segmental parameters. This study presents a novel set of algorithm to locate three-dimensional center of gravity position. The purpose of this novel system is to aid stablishing the gravity plumb line for rehabilitating patients.
Control variables employed in this study were angular positions of ankle joints, knee joints, hip joints, shoulder joints, elbow joints, wrist joints, waist joint, and the neck. The study was grounded in five sources: the human body model by Zatsiorsky and Seluyanov [1], three basic homogeneous rotation matrices, three basic homogeneous translation
matrices, a 4×4 identity matrix, and seven homogeneous transformation matrices developed by Chiu [2]. The first step in adopting this novel set of algorithm was to define body joints as 38 degrees of freedom. Then an algorithm was developed to locate the center of gravity position. Three male subjects participated in this study. Two motions were simulated by a computer. The first simulated motion was a subject squatting and then rising. During this squat, both arms swing from position at the sides of the body to a position adjacent to the head. During the second simulated
motion, the subject leans horizontally at the waist from left to right, with both arms swinging upward. The experimental results demonstrated that the computer program successfully simulated the angular positions of particular postures, and the algorithm effectively established the relationship between the angular positions and the plumb line of the center of gravity. This novel system can assist paralyzed patients and those with muscular dystrophy by ensuring that correct postures are employed during rehabilitation. Furthermore, this system can also locate the center of gravity position during running, jumping, and walking.