Basic research of upper limb work support system “My cybernic robot arm” for hemiplegic persons

Abstract

Hemiplegic persons have difficulties in handling many kinds of tasks in daily life because they must perform the tasks by only the unaffected arm and hand. In order to realize upper limb work support for hemiplegic persons, a robot arm that has ability to grip various daily necessities and cooperate with the nonparalyzed side in same work space is required. The purposes of this study is to develop a novel assistance system “My Cybernic Robot Arm” that has measurement function and adjustment function of grip force, and to confirm the basic performance of the system through the benchmark experiments. The system is composed of a robot arm and hand, a sensing unit and a control unit. The system has grip force adjustment function and learning function of grip force by grip force teaching playback. The robot arm has six degrees of freedom and was designed with minimum size to cover an area of the table tasks so as not to narrow the work area of the nonparalyzed side. The sensing unit can measure the grip force and centroid position of grip force calculated by using a capacitance feature. In addition, developed sensing unit is small enough to be embedded in the fingertip of robot hand. We conducted verification of the sensing unit accuracy and grip force teaching and reproduction as basic experiments to confirm the basic performance of the system. The results showed that the system could measure grip force and load center of gravity position. In addition, it was confirmed that the system could learn the appropriate grip force and adjust the grip force by grip force teaching playback. In conclusion, the system has basic performance because it can grip the object with appropriate grip force. This system is expected to support upper limb work of hemiplegic persons such as desk work in everyday life, and improve QOL (Quality of life) and encourage independence.