Dynamic Trajectory Planning for Robotic Knot Tying

Knot tying is an important component of surgery. When surgeons perform such operation via a tele-operated robotic system, the limited dexterity and field-of-view often poses technical challenges to the surgeons. In this paper, a new knot tying method is proposed to enhance the quality of robotic knot tying practice with low supervision. The trajectories of the instruments that can maintain the suture tension during the loop winding were formulated through the developed equations and MATI AR was employed to simulate the trajectory profiles. The grippers of the two instruments were then manipulated to grasp the suture and dynamically follow the pre-defined trajectories so that a suture knot can be constructed. Experiments were conducted and the results confirm that suture loops can be successfully winded around the instrument without suture slippage.