Development of upper limb support system for heavy work over head

Abstract

At demolition or construction sites, workers have to handle heavy tools and materials over head. It is difficult to continue such works, and the work efficiency will be reduced. A wearable support system with enough range of motion (ROM) and power will be effective to continue these heavy works for a long time. The purpose of this study is to develop a wearable upper limb support system for the heavy work over head, and to confirm the effectiveness of the developed system through basic experiments conforming to the actual works. Link structure with redundant Degree Of Freedom (DOF) was designed to move joints of wearers smoothly, and a prototype was developed for evaluation. Basic experiments with and without the developed system were conducted to confirm the effectiveness of the system. In the experiment to assess the mobility, we measured ROMs of each joint of the subjects. In the experiment to assess the effect of the system, each subject held a heavy load and moved it vertically over head, and we measured the holding time and the number of times of vertical motion. As results, we confirmed that the system had enough ROM to move smoothly. Moreover, we confirmed that the average holding time with the system increased 3.5 times than without the system, and the average number of vertical motion with the system increased 3.1 times than without the system. In conclusion, we could develop the wearable upper limb support system for the heavy work over head that had enough ROM by the link structure with redundant DOF, and confirm that the developed system was effective in continuing the heavy work over head for a long time.