Abstract
This paper newly develops a novel robotic joint mechanism by means of twisting a small-diameter round-belt, which enables slow movements of the joint rotation unlike direct-drive actuator mechanisms. The actuator mechanism proposed in this manuscript is composed of a couple of small-diameter round-belts located at near the joint with opposite configuration. The two round-belts are twisted by DC motors placed on a motor stage, which can be activated by a step motor. This novel mechanism realizes that the robotic joint is able to move around its axis due to contraction forces generated by twisting the both round-belts. That is, these round-belts act as agonist and antagonist actuators for the robotic joint, which give a human-like compliance in the joint revolution. Experimental results using the one-link robot proposed show that extremely high position resolution on the joint control can be achieved by the increase/decrease of twists of the round-belts. In addition, we clearly indicate a relationship between the amount of twist and the joint angle of the robot. Finally, experimental results can clearly explain that one DC motor acting for the joint motion activates adaptively in accordance with the slow movement of the other DC motor moving to the desired angle.
