Research On Methods Of Multi-target Data Association On The Condition Of Doppler Blind Zone

In the complex and variable detection environment,RCS fluctuation of target,target maneuver,Doppler blind zone(DBZ),aircraft attitude change and different types of jamming has bad influences on detection performance of airborne early warning(AEW)radar,causing plot disappearance and track discontinuity.The DBZ is the most important one of all influence factors.The radar couldn't detect the target located in the DBZ in several continuous scanning periods,which accordingly causes frequent initiation and termination of target track and decreases intelligence quality of radar.In multi-target environment,false alarm and dense targets enhance bad influence of DBZ on target tracking,containing higher data association error rate.This thesis improve some target tracking methods to solve the problems.The specific pursuits and innovative contributions of this thesis are concluded as follows:(1)The source and characteristics of Doppler blind zone(DBZ)and influence caused by DBZ are studied.First,formation mechanism of DBZ in PD radar is studied,and the DBZ characteristics are analyzed from relative motion state between target and radar.Second,the influence of DBZ on multi-target tracking performance in three aspects including filtering performance,data association and track quality is analyzed.(2)Considering tracking accuracy reduction in DBZ,the tracking filtering algorithm is studied based on target motion state constraint.The idea of this method is to incorporate the priori information about DBZ into filtering algorithm effectively.First,the particle filtering algorithm on the condition of DBZ is studied.The method can improve estimation accuracy of target state with the motion state constraint of target in DBZ.Second,considering multiple motion types of target in DBZ,a new interacting multiple model-blind Doppler particle filter(IMM-BDPF)is proposed.The simulation result shows that the IMM-BDPF has a lower estimation error of target state than traditional IMM-EKF.(3)Considering data association and discontinuous target track of multi-target on the condition of DBZ,based on two ideas including tracking while association and track segment association,the continuous multi-target tracking methods are studied for AEW radar.First,the measurement-track association methods are proposed based on two-dimension assignment and multi-dimension assignment.The two algorithms both utilize DBZ prior information to modify assignment cost function,and then auction algorithm and Lagrange relaxation algorithm are employed to complete optimal assignment.The entire multi-target tracking method in clutter environment is given based on IMM-BDPF algorithm and the above association algorithms.Then,on the condition of target track termination,a multi-target track segment association method based on two-dimension assignment with post-processing idea is proposed.