2P1-J10 軟体型圧力センサによる電動義手の駆動 : 操作性の改善のための圧力センサの入出力特性調整と手首回旋機能の付与

Abstract

The popularization level of the electric arm prosthesis in the present Japanese market is still very low due to the high cost and the lack of function, safety, etc. Our purpose is to know how to make cost-effective electric arm prosthesis to popularize it. In our previous research, we made an electric arm prosthesis and applied a balloon shaped soft pressure sensor's signal to control the opening and closing speed and grasping force of the finger. However we found that it was difficult to control open and close speed and grasp force of the finger well. We thought the sensor had two problems. First is that the sensor's output voltage gain is too high. Therefore, we required fine-tuning power to drive the electric arm prosthesis. Second is that the output voltage did not change from default position to pushing the sensor 2mm. Therefore the sensor's response was poor. Based on the above findings, we have investigated how to improve the linearity of the pressure sensors in the initial deformation area. After investigation, we found that the white color of the sidewall of the inner space of the balloon made a diffuse reflection. We made a refined sensors that has black inner sidewall and white inner ceiling at the top side. By using this refined sensor and decreasing the gain of the amplifier, the response in the initial deformation area was improved drastically and we got the much better controllability of the finger opening speed and finger grasping force. Furthermore, we made a wrist-unit to add rotational function of hand and drove it by the additional pressure sensors to measure the movement of the ulna and radius. The operator can control well both grasping function and twisting function simultaneously.