Abstract: To evaluate the comfortableness of ranges of motions of human upper limb joint,an evaluation method based on both the subjective scale method and sEMG signal analysis was worked out under the condition of external load.Comfortableness experiments were carried out with 12 healthy malesas subjects.The sEMG signals of 12 joint parameters at the lower shoulder,elbow,ulnar and wrist joints at different activity angles (0% ROM,25% ROM,50% ROM,75% ROM and 100% ROM) were collected.And subjective feelings were evaluated.Results show that under the 1.5kg load,the most comfort joint motion is the elbow joint flexion,followed by shoulder flexion and shoulder horizontal flexion,that the most discomfort motion is the shoulder horizontal extension,followed by wrist extension.For the elbow flexion and other four joint motions,there is a significant correlation between sEMG and subjective scores,and that the sEMG signals reflect the comfortableness of joint motion more sensitively than subjective rating.

Key words: range of motion (ROM), surface electromyography (sEMG), external load, comfortableness, ergonomic