Research On Autonomous Suture Of Robot Assisted Minimally Invasive Surgery

Robot assisted minimally invasive surgery has higher operation precision and better surgical quality than traditional minimally invasive surgery.However,the current surgical robot system is not intelligent,so that for some routine surgical tasks,the completion time of robotic surgery is not significantly better than that of traditional minimally invasive surgery.In order to further improve the effect of surgery researchers have conducted research on robotic autonomous surgery.As one of the most common and time-consuming surgical tasks in surgical operations,suture consists of three standard actions: inserting needle,pulling needle,and pulling suture.The difficulty of realizing autonomous suture by robot is low,the risk is small,and the autonomy can greatly shorten the operation time and reduce the fatigue of surgeons.Therefore,the autonomous suture technology has been widely studied.At present,the research on autonomous suture of robots is mainly to realize the robot autonomously complete single or multiple suture actions from the kinematics point of view,without fusing force information.In fact,in order to obtain a good suture effect,force-position control is a more ideal control method.In addition,the stitch placements for inserting needle and pulling needle and the needle grasping posture of the instrument need to be selected when suturing.Since the suture requires the coordination of multiple robotic arms of the surgical robot,a multi-arm collaboration plan needs to be developed.However,at present,these tasks are all performed by surgeon,but during surgery,surgeon can only observe the condition of the lesion area and the position of the surgical instrument end in the abdominal cavity through endoscopic images,and cannot perceive the overall working form of the robot’s multiple robotic arms.Therefore,when suture is performed according to the decision made by the surgeon,there are often situations that are not conducive to suturing,such as interference between surgical instruments.Aiming at the existing problems of robot autonomous suture technology,this paper has carried out supplementary research.The specific contents are as follows:1.Research on the force-position characteristics of biological soft tissue during suture process: the in vitro suture experiment of biological soft tissue was designed and implemented;Based on the experimental data,the interaction parameters that have a significant impact on the interaction force between the needle and the tissue are analyzed,and the soft tissue suture force-position characteristic characterization model fused with the interaction parameters is established,which can provide mechanical data for the further establishment of the robot autonomous suture force-position hybrid control model.2.Research on automatic assignment algorithm of suture task: the working mode of robot assisted minimally invasive surgery,the characteristics of suture task and robot structure are analyzed,and an assignment criterion is proposed to reasonably assign multiple subtasks involved in the suture process to multiple manipulators;the criterion is described digitally,and the autonomous assignment algorithm of suture task is established.3.Research on the algorithm for autonomous selection of stitch placement and needle grasping posture in robot-assisted minimally invasive surgery: Through the analysis of traditional surgical suture requirements,the stitch placement selection method that can achieve the best suture effect is refined;According to the characteristics of robot assisted minimally invasive surgery,the method was improved and an algorithm for autonomous selection of stitch placement was established;The needle grasping posture of the instrument is described in a parameterized manner.Based on an improved particle swarm algorithm,an autonomous selection algorithm for needle grasp posture was established.Finally,the two aspects are integrated to form a systematic algorithm for the robot to select the stitch placement and needle grasping posture automatically.4.Experimental verification: A verification experiment was designed and implemented,which verified the accuracy of the established force-position characterization model;Under the guidance of surgeons,a mathematical model of the patient’s physiological structure,wound position,and incision position was established.Based on the model,simulation experiments were performed on the stitch placement and needle grasping posture selection algorithm,and the suture task autonomous assignment algorithm,which verified the effectiveness of these algorithms.