抄録
In the present paper, we discuss how the human subject controls the hand position and force depending on task objects, and what roles the arm redundancy and the muscle impedance regulation play in rotation movements.
From the measurement of the hand force and the arm posture in the execution of crank rotations, it was found that the subject made the wrist joint impedance large and generated the hand force in the direction normal as well as tangential to the crank rotation. Impedance analysis demonstrated that the high impedance of the wrist joint, realized by the simultaneous activities of flexor and extensor muscles, was able to provide for the posture of redundant arm without limiting the hand manipulatability. Then it was shown that the hand force in the outer and normal directions contributed to increase the robustness of the hand manipulation against the external disturbance.
