Study On The Modeling And Analysis Of Needle Bending And Tissue Deformation During Puncture And The Study Of Puncture Path Planning

With the rapid development of society and the improvement of productivity,people's quality of life has been largely improved.At the same time,however,poor lifestyles and environmental pollution pose a great threat to people's health.According to the results of the 2018 World Cancer Survey,there were approximately 18.1 million new cases in 2018,an increase of about 4 million compared with 2012.The number of cancer deaths worldwide increased from 8.2 million in 2012 to 9.6 million in 2018.Live tissue examination(referred to as biopsy)is currently one of the most effective means of cancer detection.And percutaneous biopsy has become the main development direction of living body detection because of its small trauma and low cost.However,due to the complex environment of the body,the deformation of the tissue and the bending of the puncture needle,the percutaneous biopsy puncture still has the problem of low puncture accuracy and low efficiency.In view of the existing problems,this paper carries out the modeling analysis and path planning research of needle and tissue interaction during the puncture process,in order to improve the accuracy and efficiency of puncture sampling.The constitutive equations of the organization were obtained on the previous research of the research group.Based on the Kelvin model and the three-element model,a spring-damping-node model was established.The different force locations and force magnitudes were analyzed.The effects of the volume were simulated using Abaqus finite element simulation software.The effectiveness of the model is proved by comparing the different stress and strain relationships obtained by simulation with the established model.In this paper,the bending deformation of the needle was studied by analyzing the interaction between the tissue and the needle.The bending of the flexible needle in the tissue could be characterized by the bending of the Euleranuli beam.The flexible needle was regarded as the cantilever beam,and the relationship between the force and the deflection was obtained by theoretical derivation.Through the analysis of the needle puncture process,it was considered that the needle was subjected to the cutting reaction force,the friction force and the tissue deformation resistance during the puncture tissue process,and the factors affecting these forces include needle diameter,tip inclination angle,puncture speed,gelatin mass ratio and puncture depth.Exploring the bending characteristics of the needle provides a theoretical basis.The gelatin prosthesis was used as the experimental object to carry out the puncture experiment,and the relationship between the approximate arc radius and the puncture depth,gelatin mass ratio,puncture speed,needle radius and tip tilt angle was explored.The experimental results show that as the puncture depth increases,the equivalent arc radius increases gradually.With the increase of the tip angle of the needle tip and the radius of the puncture needle,the equivalent radius of the arc increases gradually;The decrease in water content and the increase in puncture speed in the prosthesis will gradually decrease the equivalent arc radius.In order to facilitate the flexible needle path planning experiment,a three-degree-of-freedom puncture platform consisting of two parts,the control system and the execution system,was built.At the same time,a set of step ladder control algorithm was written for the control system of the platform.It could adjust the angle of penetration,straight needle and needle through the coordinated movement of three stepping motors,which could reach high precision in the experiment.This paper introduced particle swarm optimization as a search algorithm for path planning.Taking the angle of the central arc of the single-stage arc and the angle of rotation between the arcs as the variables,the distance between the end point of the last arc and the target point was set as the objective function,and the convergence of the central angle was obtained by setting an appropriate learning factor.A combination of rotation angles to plan a flexible needle insertion path that met the accuracy requirements.The results of the planning were verified by experiments.The experimental results show that the puncture using the path planning method can keep the distance between the needle point and the target point within the accuracy range.