Robotic knot tying through a spatial trajectory with a visual servoing system

Robot assisted surgery has become increasingly popular with the rapid development of more sophisticated robotic systems. Nevertheless, there are still many tedious surgical tasks that remain to be performed manually by surgeons with high supervisions. One example is to tie a surgical knot during the surgery, which includes the processes of needle threading, suture looping, suture tail grasping and suture pulling. In this research, we present a new method for robotic suture looping process. This method is based on a spatial trajectory planning for the surgical instruments, where challenges such as suture slippage and potential collisions between the instruments could be eliminated. In contrast to conventional looping process, a dynamic control scheme is proposed to optimize the time and workspace required to complete the process. Vision information is incorporated in order to enable closed loop control of the robotic system with Linear Quadratic (LQ) controller. A series of experiments were conducted in order to examine the performance of the proposed control scheme and the results confirmed that surgical knots can be successfully tied robotically, offering new insights to the field of automated robotassisted surgery.