Research On The Robot Control System For Minimally Invasive Abdominal Surgery

Robot assisted minimally invasive surgery can reduce the trauma of patients and shorten the time of postoperative rehabilitation,so it is favored by patients.In this paper,the control system of robot assisted minimally invasive surgery system is studied,including master-slave visual control,kinematics of flexible surgical instruments and comfort of master manipulator.Firstly,according to the structure of the minimally invasive surgical robot,the kinematics models of the master manipulator,the slave robot and the flexible surgical instrument are established,and the corresponding relationship between the change of the length of the driving rope and the change of the end position of the flexible instrument is established.Software and hardware: the hardware system adopts the control mode of upper and lower computer,and the motion control card realizes the multi axis real-time motion control,which improves the real-time performance of the system,and the software system modularizes to realize the master-slave switching control of multi manipulator.Control strategy: according to the characteristics of master-slave heterogeneity and master-slave control,a control strategy of pose separation is proposed to realize master-slave incremental control;According to the working characteristics of minimally invasive surgery incision position fixed,the transformation relationship between endoscope and surgical instrument coordinate system is established,and the master-slave visual control is realized.In order to improve the comfort of the doctor’s manipulation,a rod length optimization method is proposed for the self-developed 7-DOF pose decoupled series main manipulator.According to the requirements of minimally invasive surgery,this method established several optimization indexes about the workspace and dexterity of the main manipulator by using ergonomics and kinematics of the main manipulator,and established the comprehensive performance index of the main manipulator rod length optimization by using the combination weighting method.The main manipulator performance test experiment is designed to verify that the optimized main manipulator workspace covers the human limit operation space and human comfort space,and has high dexterity in the human limit operation space.Using the self-developed master manipulator to control the flexible instrument in the field of view of endoscope,the operator controls the instrument through the master manipulator,so that the feedback image of the instrument has the same movement trend as the master manipulator,which verifies the effectiveness of the kinematics and master-slave control strategy of the robot system,The slave robot can complete the master-slave visual control under the control of the master manipulator,and record the master-slave follow-up trajectory through the 3D motion capture system.Through the comparison of the master-slave follow-up trajectory,it is verified that the robot system has good motion accuracy.Finally,the small ring grasping experiment shows that the robot system can achieve fine operation under master-slave control.