Research On EMT Image Reconstruction Algorithm Based On Multi-objective Optimization Of Homotopy Algorithm

Electromagnetic tomography(EMT)which was produced at the end of the 1990 s,a system based on electromagnetism theory,is mainly used to research the distribution of materials with electromagnetic properties within space.EMT technology has many prominent characteristics,such as non-invasive,simple structure,no contact,no harm,detected magnetic materials,wide application and so on,so EMT has a huge technical advantages in the future industry.After about twenty years of research,EMT technology has made great progress,but there is still existence of underdetermined,soft field effect,nonlinear problems.Thus,the image reconstruction accuracy of EMT system is low.So,it is important to study the reconstruction algorithm of electromagnetic tomography system.These difficulties still need the scholars to research and solve.This paper mainly focuses on the homotopy algorithm,multi objective optimization algorithm and inverse problem of EMT system to conduct research,the following work is accomplished:Firstly,according to a great quantity of literature at home and abroad,the origin and development of EMT technology,recent research on home and abroad,specific application category and the basic principle and composition of EMT system are elaborated.The basic principle and structure of EMT system and several common methods of image reconstruction are elaborated.The basic principle of homotopy algorithm and the mathematic model of homotopy method are introduced,and then the corresponding formulas are deduced,and the homotopy algorithm is applied to the electromagnetic tomography system.Secondly,in order to solve the problem of poor quality of image reconstruction in electromagnetic tomography,it is improved on the basis of homotopy algorithm,combining the mathematical equations of multi-objective function.Using the theory base of multi-objective optimization to determine the three target functions selected in the improved homotopy algorithm,which is the sum of the squared error of themeasured voltage and the estimated voltage,smoothing criterion function and total variation regularization criterion function,the mathematical optimization model of multiple target functions is established,on this basis,the realization steps of reconstructed image is finally obtained,so an optimal solution of EMT image reconstruction is obtained.Finally,the proposed method is verified by simulation experiments.The EMT model is built by Comsol software,then the simulation data is obtained,and the corresponding method is used to reconstruct the image in Matlab.Simulation test results show that the homotopy algorithm based on multi-objective optimization is a valid EMT image reconstruction method.This method with small difference and high precision,and its relative error and correlation coefficient are all superior to LBP,Landweber and Tikhonov common algorithms.The final result of simulation test shows that the multi-objective optimization homotopy image reconstruction algorithm is an effective and accurate image reconstruction method of EMT system.