Development of motion control algorithm for upper limb support system based on bioelectrical signals for heavy work over head

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. In order to continue these heavy works for a long time, we have developed a wearable upper limb support system for the heavy work over head. In the actual works, it is necessary for the system to perform motion support in synchronization with motor intention of wearer. Bioelectrical signals (BES) are effective as the motor intention of wearer for such the motion support. The purpose of this study is to develop motion control algorithm of upper limb support system based on the BES for heavy work over head, and to confirm the effectiveness of the developed algorithm and the system through evaluation experiments. The system supports wearer's upper limb motion by actuators in each joint of the system. Control phases of the system are changed by the developed algorithm based on BES. The wait phase is switched to the support phase, and the support phase is switched to the wait phase. Evaluation experiments were conducted to confirm the effectiveness of the developed system. In the experiment to assess the performance of the developed algorithm, we measured the switching time of the control phases of the system. In the experiment to assess the effect of the system, a volunteer held a heavy load over head with and without the system, and we measured the holding time. As results, we confirmed that the control phases of the system changed in synchronization with motor intention of the wearer. Moreover, we confirmed that the holding time with the system increased 2.8 times than without the system. In conclusion, we could develop the motion control algorithm of the upper limb support system based on BES for heavy work over head, and confirm that the developed system with the algorithm has effectiveness for continuation of the heavy work over head.