A 3 mm Wristed Instrument for the da Vinci Robot: Setup, Characterization, and Phantom Tests for Cleft Palate Repair

Cleft palate is a congenital defect that affects approximately 1 in 800 births worldwide. A robotic approach for cleft palate repair is desired due to the potential ergonomic, vision and accessibility improvements in the small workspace of the oral cavity. This paper presents a 3 mm, 4-degree-of-freedom instrument for use with the widely available da Vinci system. The pin-jointed wrist design features cable guide channels in place of pulleys, significantly reducing the size of the wrist. Additionally, a novel cam mechanism minimizes any potential cable slack resulting from the lack of pulleys. The accuracy of the novel wrist was found to be 1.4° for motion in the same direction and the slack reducing capability of the cam mechanism was verified. Despite the 11.9° of hysteresis, there was no noticeable impact to teleoperation as the instrument was used to successfully perform suturing with the da Vinci Research Kit. Furthermore, contact between the tools and the oral aperture during surgery is significantly lower for the 3 mm instrument when compared to current 8 mm instruments. In summary, the novel instrument has the potential to better facilitate the adoption of a robotic approach.