Design of a dexterous robotic surgical instrument with a novel bending mechanism

Background The robot-assisted minimally invasive surgery (RMIS) has developed rapidly in recent years, requiring highly articulated instruments to enable surgeons to perform complicated and precise procedures. Methods A novel wrist-type surgical instrument was proposed for RMIS. The wrist consists of superelastic-wire-driven snake-like joints and universal joints, which could perform two deflections and one distal rotation. The bending mechanism and the kinematics of universal joints were analysed. The forward and inverse kinematics of the wrist were derived. Results The performances of the instrument were evaluated using a prototype by experiments. The average motion deviation of the wrist's deflection was 0.15 +/- 0.08 mm, and the maximum deviation was 0.52 mm. The maximum payload capability was 10 N. The suture task and ex vivo procedure verified the effectiveness of the instrument. Conclusions The proposed instrument has high dexterity and payload capability, which contributes to improving the quality of the RMIS procedures.