Mechanical designs of active upper-limb exoskeleton robots: State-of-the-art and design difficulties

Active upper-limb exoskeleton robots have been developing from 1960s. In recent years, the mechanical designs and control algorithms of active upper-limb exoskeleton robots were developed significantly. This paper reviews the state-of-the-art of active upper-limb exoskeleton robots that are applied in the areas of rehabilitation and assistive robotics. In addition, the main requirements of the active upper-limb exoskeleton robot are identified and the mechanical designs of existing active upper-limb exoskeleton robot are classified. The design difficulties of an active upper-limb exoskeleton robot are discussed.