Structure Design And Puncture Control Of FBG Embedded Cannula Flexible Needle Insertional Robot

Percutaneous puncture surgery is widely used in modern clinical practice.At present,rigid needle puncture with bare hands is adopted clinically,but it has inherent limitations.While the flexible needle controlled by the puncture robot can complete complex puncture trajectory,avoid obstacles such as bones,blood vessels and nerves,and it has great advantages and potential in improving the precision of targeted puncture,surgical efficiency and safety.At the same time,the puncture needle penetrates into the human tissue during the puncture,and its state is invisible to the naked eye,which can only be observed by the way of medical images such as ultrasound,CT,and MRI.However,there are some problems such as material limitation and radiation hazard in these imaging methods,and the real-time performance or accuracy cannot be completely met.Therefore,aiming at the precise puncture of prostate target by the puncture robot,this thesis carries out the research on the structure design of puncture robot,shape perception of flexible needle and puncture control.The flexible needle controlled by puncture robot with FBG embedded cannula is designed.After analyzing the design requirements of prostate puncture robot,the degree of freedom of the robot is allocated,and the configuration is selected and the spatial layout is determined.In this condition,the structure design of the puncture robot is completed,and the forward and inverse kinematics of the robot are analyzed.The workspace of the puncture robot is simulated by Monte Carlo random sampling method,and the simulation results show that it can meet the operating space requirements of clinical prostate puncture surgery.A method for flexible needle shape sensing based on FBG sensing is proposed.According to the principle of FBG sensing,the FBG sensor is integrated into the flexible cannula needle,and the FBG embedded flexible cannula needle is designed.A curvature and torsion estimator based on extended Kalman filter algorithm is designed,and the discrete curvature and torsion of the needle at different positions are obtained.Finally,a numerical method for reconstructing the shape of the needle and calculating the position of the needle tip is proposed.A tracking control method for the puncture path of FBG embedded cannula flexible needle is proposed.The kinematics of flexible cannula needle is analyzed,and the puncture path is planned by improved RRT algorithm.However,due to the existence of uncertain factors such as tissue heterogeneity and control error among individuals,the puncture needle will deviate from the predetermined path.For this reason,the fuzzy controller designed takes the shape-sensed tip position error and the error rate of change as feedbacks,calculating the control offset online,and controls the puncture robot to adjust the puncture trajectory of the needle,so that it realizes the puncture path tracking control of FBG embedded cannula flexible needle,and improves the puncture accuracy.Shape reconstruction and puncture control experimental verification are carried out.Based on the research content of this thesis,the experimental platform of puncture system is built.The single and double curved shape reconstruction experiments of the needle are carried out,and the experimental results show that the method of shape perception has high real-time shape perception accuracy.Moreover,in the puncture environment with obstacles,many puncture experiments have been done on the target.The experimental results show that the proposed method for puncture path tracking control has better path tracking ability and higher puncture accuracy.