Abstract:Lifting with a single arm is a common upper-limb action but it is easy to cause the rotator cuff injury. An upper-limb exoskeleton was designed to provide assistant force/torque to the human for accomplishing the lifting task on the premise of safety. The proposed prototype was comprised of two parts: 1-DOF elbow exoskeleton and a pneumatic shoulder pillow. The proposed structure was combined with the benefit of power transmission in the rigid exoskeleton and flexible double weave shoulder movement in the bionic exosuit. Such devices can provide necessary force assistance for the elbow flexion/extension and shoulder abduction of the wearer and improve the kinematic compatibility between the human arm and the exoskeleton. Further on, to verify the performance of the exoskeleton, a subject was asked to lifting 1kg and 5kg weight of loads with and without the robot-assisted, respectively. From the results, the mean absolute values of electromyography on biceps and supraspinatus were reduced to 70.97% and 80.67% of the non-wearable state during the 1kg weight lifting task, and 69.92% and 81.51% in the 5kg weight lifting task. The root mean squares of the relative muscle electromyography were reduced to 78.85% and 78.02% in 1kg, and 66.46% and 89.22% in 5kg. By using the pneumatic abduction shoulder pillow, the abduction trajectory of the shoulder was similar to the natural state during the lifting tasks. The heart rate of the subject was also recorded in the experiment. From the statistical analysis, the heart rate was not obviously changed (p>0.01). These results illustrated the potential risk of rotator cuff injury can be reduced in the robot-assisted lifting task.