Design and evaluation of a gravity compensation mechanism for a humanoid robot

Performance of a human size humanoid robot is strictly limited by performance of the motor. The progress of a motor has not been remarkable compared with the progress of electronics. Therefore, the great progress of the performance of the motor cannot be expected, at least in the present circumstances. In this paper, a gravity compensation mechanism is designed which is applicable to a general biped robot. The mechanism is expected to reduce the joint torque of the legs required to support the gravitational force of the whole body. A humanoid robot Saika-4 is equipped with the gravity compensation mechanism in the legs. To evaluate effectiveness of the gravity compensation mechanism, preliminary experiments are performed using the humanoid robot.