Research On Helical Vascular Robot Driven By External Magnetic Field

Cardiovascular disease is one of the main threats to human health.How to eliminate the harm of cardiovascular disease is one of the important issues in the world medical field.Traditional intubation treatment will bring great pain to patients.Minimally invasive surgery with the advantages of small trauma and easy recovery has become a hot spot of medical research.The combination of minimally invasive surgery and vascular robot in human treatment has gradually become the mainstream trend of medical research,and has great application potential.In this paper,the external magnetic field driven spiral vascular robot is studied.In order to solve the driving problem of the vascular robot,a safe three-axis Helmholtz coil is used as the magnetic driving module.Considering the safety problem of the vascular robot in operation,an internal spiral vascular robot is proposed,and the interaction mechanism between the blood flow field and the vascular robot is studied.The main contents of this paper include the following four parts:(1)Design of external driving module and vascular robot.Firstly,by comparing the advantages and disadvantages of the existing micro robot drive mode,and analyzing and summarizing,the magnetic drive mode is determined;secondly,by comparing the working principle and advantages and disadvantages of the magnetic field of electromagnetic coil,permanent magnet and imager,the electromagnetic coil three-axis Helmholtz coil is finally adopted as the drive module scheme.Based on the structural safety problem of vascular robot,the innovative design method of IASE(identification,analysis,solve,evaluation)is adopted.Firstly,on the basis of structural analysis of vascular robot,the problem to be solved is determined,and the invention principle to solve the corresponding problem is determined by contradiction analysis.Combined with extension analysis and extension transformation,the solution is obtained,and finally with the help of optimization The optimal scheme is selected by degree evaluation,and the final scheme of internal spiral vascular robot is obtained.(2)Magnetic field analysis of magnetic drive module for vascular robot.By analyzing the working principle of Helmholtz coil,the three-dimensional rotating plane coordinate system is established,and the magnetic induction formula of rotating magnetic field is obtained.According to the theoretical formula of the magnetic drive module,a three-axis Helmholtz coil drive module is designed to meet the experimental requirements,and the magnetic field distribution characteristics of each axis coil are obtained through numerical simulation.According to the simulation results,the uniformity of each axis coil is analyzed.Compared with the combined coil,the uniformity of the three-axis Helmholtz coil designed in this paper is better,and the magnetic field uniformity meets the design requirements requirement.Furthermore,the influence of coil turns and input current on magnetic field intensity is analyzed,and the generation of rotating magnetic field is verified,which has guiding significance for the design of drive module.(3)Structure design and optimization of internal spiral vascular robot.In order to verify the feasibility of the internal spiral vascular robot scheme,the models of blood vessel and internal spiral vascular robot are established.The dynamic simulation method is used to carry out numerical simulation.Taking axial thrust and liquid resistance as optimization indexes,the inner diameter,spiral lift angle,groove depth,screw width,front opening degree and rear closing degree are optimized and analyzed.Combined with the design requirements and driving indexes,the conclusion is drawn The operation performance of the micro robot is better than that of the structure parameter group.The numerical results show that the axial thrust of the optimized model is increased by 1.12 times than that of the original model,while the liquid resistance moment is only increased by 0.03 times.(4)Swimming characteristics of vascular robot in pulsating flow field.In the blood pulsating environment,combined with the sliding grid method,the axial force and liquid resistance moment of the internal spiral vascular robot in a cardiac cycle are numerically studied,and the variation of pulsating flow field at each typical time is analyzed.Furthermore,the effects of vascular environment parameters(density,viscosity and diameter)on the axial thrust,liquid resistance moment and shear force on the vessel wall of the internal spiral vascular robot were analyzed.Finally,the two-phase flow field of blood vessel is studied as a three-dimensional model of Eulerian two-phase flow and bifurcation free flow.It can provide valuable reference for clinical interventional therapy.