Wearable passive upper-limb exoskeletons have been proposed and commercialized as tools to improve the ergonomics of workers in repetitive or physically demanding tasks. In the study presented here, an innovative upper-limb exoskeleton is presented, along with experimental tests with human subjects. The device, called proto-MATE, is characterized by two distinguishing design features: a highly ergonomic human-robot kinematics architecture and bioinspired assistance, created to partially compensate for the user's arm weight. Experimental tests investigated the device's effects on the physical strain of eight upper-limb muscles. These tests also quantified the kinematic coupling between the device and the user by means of specific kinematics-related parameters. The protocol included overhead tasks that are representative of the target application and tasks that generalize nontargeted upperlimb movements and may occur in real working conditions.
