Abstract
The paper describes development of a shoulder joint teaching equipment for the athlete to learn proper movement of his shoulder in such sports and games as baseball and tennis. A simple 4DoF model of the scapula, which can change position relative to the human body, is proposed. The scapula is attached to the human body via four or more muscles. The proposed model has links between the scapula and the human body, and four sliding actuators. The motion of the scapula is analyzed, the position and posture of the scapula are obtained, and actuators' output force is analyzed. In order to examine the validity of the analysis, the result is compared with the past studies.
