“…Therefore, most of the exoskeletons supporting motions of two or multiple joints, such as shoulder–elbow [ 29 , 47 ], elbow–wrist [ 8 , 26 ], or shoulder–elbow–wrist [ 16 , 17 ], found in the literature, were not portable. Apart from that, some studies also mentioned fixed exoskeletons supporting a single joint motion, which were mainly elbow exoskeletons [ 9 , 17 , 21 , 25 , 30 , 33 , 34 , 37 , 40 , 47 , 53 , 62 , 63 ] (except one shoulder exoskeleton in [ 68 ] and one hand exoskeleton in [ 36 ]), which were not portable because of their high weight-to-power ratio.…”