Shoulder Position Estimation using Load Current Shape

This paper presents an improved shoulder position detection method in the body scanning process of a massage chair using flex and knead motor current shape. In order to improve the relaxing and massaging effect, the strength of rolling, kneading and tapping have to be adjusted according to the muscle position of the human body. And these massage regions of the body can be estimated by the shoulder and hip position. The hip position is automatically determined by the massage seat shape. But, the shoulder position of the user has to be determined by body scanning. In this paper, a novel shoulder position estimation scheme using flex and knead motor current shape is presented. In the proposed method, the load currents of the knead and flex motor in the constant speed condition are same as the friction load between the massage ball and human body. From the neck to shoulder moving, the friction between the massage ball and human body is suddenly changed. According to the periodic operation of knead and flex motion, the motor currents are analyzed by the periodic shape form. Then, the periodic current shapes of the knead and flex motor can be used to detect the shoulder position of the user. The proposed shoulder estimation scheme is tested by the practical electronic massage chair according to the users with different height and weight. In the practical test, the proposed method can well estimate the actual shoulder positions of various users.