Three-Degrees-Of-Freedom Passive Gravity Compensation Mechanism Applicable to Robotic Arm with Remote Center of Motion for Minimally Invasive Surgery

Chang Kyun Kim1, Deok Gyoon Chung2, Minho Hwang3, Byungsik Cheon Cheon4, Hansoul Kim5, Joonhwan Kim6, Dong Soo Kwon7

  • 1Korea Advanced Institute of Science and Technology (KAIST)
  • 2KETI
  • 3DGIST
  • 4Kohyoung Company
  • 5Korea Advanced Institute of Science and Technology
  • 6Korea Advanced Institute of Science and Technology(KAIST)
  • 7KAIST

Details

11:45 - 12:00 | Tue 5 Nov | LG-R11 | TuAT11.4

Session: Medical Robot: Design

Abstract

For safety enhancement reasons, passive gravity compensation is widely applied in robotic systems used in minimally invasive surgery (MIS). MIS robotic systems have a remote center of motion (RCM) in which a surgical instrument conducts a fulcrum motion around a point of invasion. RCM mechanisms include three-degrees-of-freedom (3-DoF): roll, pitch, and translation. Existing studies to date have focused on multi-degrees-of-freedom (MDoF) gravity compensation mechanisms by installing springs and wires in a robot. However, a gravity compensation mechanism with 3-DoF that simultaneously uses all three directional movements (roll, pitch, and translation) has not yet been researched. Here, we propose a novel gravity compensation mechanism applicable to a 3-DoF MIS robotic arm with an RCM mechanism. When a translational motion is exerted, the proposed gravity compensator can adjust the roll-pitch-directional compensating torque by utilizing a reduction gear box and wire cable. To verify the 3-DoF gravity compensation, a gravity-compensated robotic arm for MIS and customized torque sensors were manufactured and calibrated. Results showed the proposed static balancing mechanism can compensate for the gravitational torque with respect to roll, pitch, and translation. The total torque error along the roll and pitch axis was less than 0.38 Nm. In particular, the torque variation due to the translational motion was less than 0.13 Nm.