Path Planning Of Cannula Flexible Needle Based On Improved Rapidly-exploring Random Tree Algorithm

The bevel-tip flexible needle can produce curvilinear trajectories to avoid important organs in the process of puncture by using the interaction between the asymmetric needle tip and tissue.However,the flexible needle has the drawbacks of poor ability to correct puncture path and low control accuracy.Therefore,we use the cannula flexible needle instead of the traditional bevel-tip flexible needle for puncture operation,and further study the kinematics modeling and path planning of flexible needle.Firstly,the kinematic model of the cannula flexible needle is established.It is carried out according to its motion principle,and through theoretical analysis of the bending characteristics,the parameters that affect the flexural deformation of the cannula flexible needle puncturing the soft tissue are determined and verified by experiment.On the basis of the detailed analysis of the path form of different cannula flexible needles,the optimal path form is determined.Secondly,based on the kinematic model of the cannula flexible needle,an improved Rapidly-exploring Random Tree(RRT)algorithm based on the target guidance strategy is proposed.By analyzing the characteristics of the basic RRT algorithm,and on the basis of it,the motion model of the cannula flexible needle and the target guidance strategy are embedded.So that the search trajectories meet its kinematic constraints and the efficiency of path search is improved.At the same time,the optimal path strategy is used to search the best path,in order to solve the drawbacks of RRT algorithm to search the optimal path.Thirdly,the improved RRT algorithm is used to carry out the path planning of multi-objective and multi-layer organizations.The entry point is optimized in the needle entry area,and the puncture plan of single entry point to multi-target point is put forward,and the path planning is carried out.Considering the situation of human multi-layer tissue,the path planning of multi entry point to multi-target point puncture is carried out.Finally,the puncture experiment of simulation human tissue was carried.The cannula flexible needle and biomimetic tissue material were prepared and the puncture experiment was carried out.The experimental results are compared with the path of the planning,and the error analysis is carried out.The feasibility of the path planning method is verified.In this Dissertation,aiming at the multi-layer structure problem of the cannula flexible needle puncture,a kinematic model of the cannula flexible needle is established,and the path planning method of improved RRT algorithm is given.The feasibility of the improved RRT algorithm is verified by the puncture experiment.It provides a solid theoretical basis for the practical application of minimally invasive percutaneous puncture.