Research On The Control Method Of Robot-assisted Percutaneous Surgery

Robot with the advantage of space location accuracy, high stability, movementagility and so on can be used to robot-assisted percutaneous surgery and can cangreatly improve the safety and efficacy of surgery. Therefore, the robot-assistedpercutaneous surgery has a very large value of clinical application. Therobot-assisted percutaneous surgery system can realize the 3D reconstruction fortwo-dimensional medical images based on the space location technology, so thatmake the the images of lesion location more clearly and make the identification oftarget lesions more accurate, improving accuracy of puncture.First, make the analysis of the traditional process of manual needle puncture,and plan the process of robot-assisted percutaneous surgery. The process consist offive parts: dragging the robot to the surface of the patients'skin, determining theentry point, adjustment of needle, controlling and monitoring of needle insertion.Therefore, study on the method of dragging robot based on the mechanicalimpedance, determining the entry point by using intended insertion path andtranslation robot, calculating the motion parameters of 2-DOF attitude-adjustingmechanism of robot according to the space attitude of intended insertion path.Analyze the three aspects of needle insertion speed: forces change of needlebody, the depth of needle insertion, the deflection of needle. And propose theestimation equation of deflection at needle tip. Then design of fuzzy controller, byusing the three aspect of needle insertion speed above as the input and the output ofcontroller is the needle insertion speed. Then make a simulation experiment of thecontroller by using fuzzy toolbox in Matlab.Studying on the location tracking of needle tip based on magnetic tracker.Make the magnetic launcher as base coordinate system, and the magnetic receiveras medium. Install the magnetic receiver in the end of needle and acquire the spatialoffset between needle tip and magnetic receiver by experiment of calibrating. Thencalculate spatial location of needle tip in the base coordinate system according tothe real-time pose transformation matrix between magnetic launcher and magneticreceiver and spatial offset. Display the lesion images real-time needle tip's positionin the VTK software platform and realize the visual monitoring of needle insertion.Use the spatial location of needle tip by magnetic tracking to measure the real-timeerrors of needle insertion, in order to monitor the safety and effectiveness of the operation.In the end, compile program to control the robot, using the visual monitoringplatform. And make an experiment to acquire the errors of location of puncturingand insertion monitoring, by using simulated insertion path and target. Then, makean experiment of puncturing the liver to acquire the error of system, using theparaffin as simulated target. The experimental results show that the error of robotcan satisfy the use requirement of clinical application, and the system has betterstability and maneuverability. The errors of system consist of three aspects: 3Dreconstruction of medical images, location of puncturing, target movement causedby soft tissue deformation and drift organ. And research on the sources and thenumerical for errors.