| Minimally invasive surgical robot is an innovative technology resulted from applying robot technology to the minimally invasive surgery(MIS).This technology is a new cross-disciplinary research field integrating medical science,mechanics,materials science,control science,computer graphics and many other disciplines,which has important research value and broad application prospects.Compared with traditional MIS,robot-assisted MIS can solve the problems of hand-eye uncoordination,less flexibility of surgical instruments,and more fatigue for doctors in traditional MIS,and improve doctors' comfort of doing MIS.On the other hand,the operation of doctor controlling the robot arms based on master-slave method can not only exert doctor's surgical experience,but also can improve the safety of the operation.For the celiac MIS robot,its control system directly affects operator's experience and surgical quality,and the research on its control system is of vital importance.In this thesis,for MIS robot ‘HuaQue II' independently researched and developed by our laboratory,the mater-slave control,intuitive ability,accuracy and safety et al..were studied,and the experimental platform was built to verify the performance.The control system of MIS robot was designed by analyzing its performance requirements and use characteristics.According to the structural characteristics of different control systems,the master-slave control structure using distributed computing and I/O connections was determined.At the same time,in order to improve the real-time performance,a control system based on QNX real-time operating system was designed.By configuring QNX system,adapting multi-thread programming technology to perform functional level division,synchronization mechanism setting,priority selection,scheduling mode selection,etc.,real-time master-slave control was finally implemented,and the respond time of the control system is verified.It was studied that intuitively controlling the MIS robot.According to the structural characteristics and control method of ‘HuaQue II',the spatial motion consistency mapping relationship between master and slave manipulators was built,and an incremental control algorithm based on separated position and gesture for the laparoscope-holding arm and and instrument arm were proposed.This algorithm was applied to realize doctors' master-slave operation with hand-eye coordination.In addition,the separated laparoscope arm and instrument arm gesture measure method based on monocular vision was proposed for the gesture relationship between them.In order to achieve precise positioning control for MIS robot,this paper proposed an error calibration method based on extended kalman filter(EKF)and artificial neural network(ANN).First of all,distance error model was built and kinematic redundancy parameter errors were eliminated and geometric parameter errors were calibrated.Then,the relationship between robot joint and residual position error was established by BP neural network method and non-geometric errors were compensated.After error calibration and compensation,positioning errors could be effectively reduced.Precise positioning control of MIS robot is carried out by using identified geometric parameters and trainded neural network.For surgical instruments replacing and master-slave initial postures matching,instrument joints homing and master-slave initial gestures matching control strategies based on step-by-step method were proposed.These could gurantee the end tip position would not move during the manipulation,so that no accidental injury was caused to the tissues.At the same time,an instrument moion constraint method on the basis of haptic virtual fixture(VF)was proposed.With this motion constraint method,the operator could set safe path or protection area with different shapes.Once the instrument leaved safe pateh or entered into protection area,force feedback generated by VF would prevent or guide the operator until the instrument return to the pre-set area which was used to improve system safety.A whole control system was designed based on the method proposed in this thesis and applied to the celiac MIS robot system ‘HuaQue II'.The system respond time and effectiveness of the master-slave control strategies and master-slave control based on FV were verified.Otherwise,the performance of master-slave tracking of MIS robot was verified after error calibration.In the end,live animal tests were conducted to verify the real-time ability,intuitiveness of master-slave operation,accuracy and safety of the whole control system. |
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