Master-slave Control Of Flexible Needle Based On FBG Sensor And Fuzzy Control Algorithm

Needle puncture is a type of minimally invasive surgery,mainly used for biopsy,local injection and radioactive seed implantation.The puncture path of the traditional rigid needle is a straight trajectory,and the operation has great limitations.However,the puncture path of the flexible needle is a smooth curve,which can bypass some important tissues and organs to reach the target position.Compared with the common bevel-pointed flexible needle,the trocar flexible needle can change the bending curvature of the flexible needle and realize a more complex puncture trajectory.In flexible needle puncture surgery,accurate control of flexible needle puncture is the key to the success of the operation.In this thesis,the shape of the flexible needle is reconstructed based on the fiber Bragg grating（FBG）sensor and the position of the needle tip is calculated and the puncture control of the flexible needle is studied and a master-slave control strategy of human-machine cooperation is proposed.Based on the feedback information of the FBG sensor,this thesis proposes a method to reconstruct the shape of the trocar flexible needle and obtain the position of the needle tip at the same time.In this thesis,the distribution of the grating in the FBG sensor is designed,and a structure of a new type of flexible trocar embedded in the FBG sensor is proposed.According to the curvature and direction of the flexible needle detected by the FBG sensor,a numerical method is proposed to obtain the position coordinates of each point on the flexible trocar,so as to reconstruct the shape of the flexible trocar and calculate the position coordinates of the needle tip.This thesis proposes a master-slave control strategy for flexible needle puncture with the Touch X force feedback device as the master hand and the flexible needle puncture robot system as the slave hand.The slave-hand robot system is analyzed,the kinematic model of the trocar flexible needle is established,and the path planning of the trocar flexible needle is carried out accordingly.The main hand Touch X force feedback device was introduced,the range of the Touch X was measured,the point-to-point spatial mapping was established,and the spatial transformation matrix was obtained.A virtual master-hand movement space with tactile feedback was established to simulate the actual puncture environment,and the principle and specific operation method of the proposed flexible needle master-slave control were expounded.After analyzing the two master-slave control methods respectively,this thesis adopts a simple and practical space point-to-point closed-loop master-slave control strategy.In this thesis,a fuzzy control algorithm is proposed to integrate a flexible needle puncture robot system from the hand.In this thesis,the bending characteristics of flexible cannula needles are studied,and the influence of different factors on the curvature of flexible cannula needles is analyzed.The relationship coefficient between the length of the needle shaft extending out of the cannula and the curvature of the flexible needle was obtained by means of a puncture experiment.When the hand robot system controls the flexible cannula needle to track the puncture along the planned path,the fuzzy control algorithm is combined to control the length of the needle shaft extending out of the cannula in real time,so as to change the curvature of the cannula flexible needle in real time,and then realize the flexible cannula target Accurate tracking of puncture for planning paths.In this thesis,the proposed new cannula flexible needle and experimental materials are prepared,and experimental platforms for the flexible needle needle shape reconstruction experiment,the master-slave follower experiment and the flexible needle puncture experiment are respectively built and verified by experiments.The experimental results of each experiment were obtained and the error analysis was carried out to verify the feasibility of the proposed method,and to provide theoretical and experimental references for the precise control of cannula flexible needle puncture.