Development of a New Bending Mechanism and Its Application to Robotic Forceps Manipulator

This paper proposes a new bending mechanism with a screw drive mechanism, which enables omni-directional bending motion by rotating two linkages consisted of right-handed screw, universal joint and left-handed screw. We call this mechanism double-screw-drive (DSD) mechanism. DSD mechanism was applied to a robotic forceps manipulator for laparoscopic surgery. In the first prototype, by adding the third linkage to DSD mechanism and rotating this, opening and closing motions of a gripper was attained. In the second prototype, DSD forceps manipulator was enhanced so that its gripper can rotate. This is achieved by rotating the third linkage in DSD mechanism. On the other hand, the opening and closing motions of a gripper is attained by wire-drive. The developed DSD forceps manipulator realizes bending motion without using wires. Therefore, it has high rigidity, and it can bend 90 degrees in arbitrary direction. In order to control the developed DSD robotic forceps manipulator as teleoperation system, joy-stick type manipulator for remote control was built and servo system was constructed for each linkage. Servo experiments show the effectiveness of the constructed control system.