Research On The Method Of Denoising Electromagnetic Interference In FASTRAK Limb Location

Electromagnetic tracking has broad prospects in the field of three-dimensional measurement,such as clinical medicine,virtual teaching and virtual surgery,because of its advantages of being independent of sight,small volume,high precision and short delay time.However,the tracking technology based on electromagnetic field is distorted by the electron-conducting objects in the measurement environment,which leads to the measurement data being distorted or completely submerged by noise.To solve this problem,a method of combining AFSA optimized wavelet thresholding algorithm and LMD to suppress electromagnetic interference is given in this paper.First of all,this paper describes the principle of FASTRAK electromagnetic limb localization,and builds a limb positioning experimental platform.Based on the actual application environment,the reasons that may cause the accuracy and stability of FASTRAK measurement data are analyzed,and the mathematical model that causes the local magnetic field distortion is described.Secondly,a method of combining AFSA Optimized wavelet thresholding algorithm and LMD is given in this paper.The proposed method decomposes the acquired data into PF components with instantaneous frequency,and compares the former n-1 PF Component AFSA-optimized wavelet thresholding;in view of the low convergence rate and low convergence accuracy of AFSA algorithm,this paper presents a method to dynamically change the perception range and moving step size of AFSA algorithm,which improves the AFSA convergence rata by 56 %.Finally,the algorithm given in this paper combined with the experimental platform set up in this article under the laboratory environment of the limb positioning experiment.The experimental results show that the root mean square error of the data using the traditional wavelet thresholding method before and after the combination of LMD and AFSA optimization and the traditional wavelet thresholding based on the LMD are 0.0784 mm and 0.0475 mm,0.0703 mm,which verifies that the proposed algorithm has better effect than traditional wavelet threshold based on LMD.In order to evaluate the FASTRAK 6-DOF data as a whole,we design the electromagnetic tracing differential device by double receivers but transmitters to simulate the mathematical model of the two receivers.The experiment.The results show that using the local mean decomposition and artificial fish swarm optimization presented in this paper,the similarity of transmission matrices of 6 DOF data before and after EMI suppression is 0.6413 and 0.8733 respectively.It is verified that the proposed algorithm has better performance for interference suppression Good robustness,and provide a reference solution for the accuracy and stability evaluation of electromagnetic positioning afterwards.