The Investigation Of Multi-target Detection And Tracking In Wideband Multi-static Radar System

The wideband multi-static radar system with omnidirectional antennae has the advantages of wide observation area,fast response,high measuring accuracy,simple structure and low cost,therefore,there is a promising application for this system in military and civil fields.However,each receiver in this system can only observe one-dimensional target information(e.g.range sum and velocity sum) in the radar LOS(line of sight),so all receivers' measurements must be integrated to estimate target's state of three-dimensional position and velocity.Due to this special working mode,the processing becomes fairly difficult when tracking multiple targets in a complex environment.To solve the problems of this radar system in multi-target detection,tracking and information fusion,this dissertation carries out research systematically in following two aspects:(1) The investigation on multi-target pairing/detection and tracking based on local track association.A new multi-target pairing and detection algorithm based on "sweeps' local track" association is proposed for the system working with symmetrical triangle linear frequency modulated continuous waves(STLFMCW).Based on the correlation of the same target in consequential observation cycles,the "local track" in positive sweep is utilized to match with that of comes from the same target in negative sweep,and the pairing performance has improved significantly.As all false tracks caused by false alarms have been eliminated in paring process,the multi-target detecting performance in dense clutters can be enhanced too.At the same time,the target's accurate range sum and velocity sum can be estimated when all targets have been paired off and detected.Then,a fast multi-target tracking method with distributed-centralized framework has been devised to accommodate the separated transmitter and receiver structure.In this algorithm,the "local track" formed in each receiver has been fully utilized.A hypothesis testing based on velocity sum information is introduced to remove all false target combinations and "local track" association can be realized.Then,the tracking techniques of local tracking in receivers(distributed treatment),"local track" association and track management in fusion center(centralized treatment) are integrated to build up a feasible multi-target tracking framework with real time performance.Since the "local track" association is adopted instead of complicated measurement-to-measurement and measurement-to-track associations in fusion center,the stability and real time performance can be evidently increased.(2) The investigation on track-crossing targets detection and information fusion of multi-aspect range profiles based on high resolution range profile(HRRP).To solve the detection problem of track-crossing targets,a new track-crossing target detection algorithm based on fuzzy C-means clustering(FCM) and range profile reconstruction(RPR) technique is presented.In this algorithm,the prediction of confirmed target is introduced as the prior information of FCM algorithm to reduce the sensitivity to initialization condition and the detection performance in clutter environment has been improved.At the same time,the average range profile of target before track crossing occurs is used to distinguish and reconstruct range profiles of superposed and inseparable targets.As a result of range profile reconstruction,the discriminable area of track-crossing targets is greatly enlarged and the reliability of state parameter extraction has been increased.To solve the problem that high resolution range profile is very sensitive to target-radar attitude,a fusion algorithm of multi-aspect range profiles is proposed based on maximum entropy principle.On the basis of target state information obtained in target tracking process,the registration and optimal weighted fusion methods are provided for multi-aspect range profiles.Then,the analytical expression of optimal weight value has been deduced and its physical meaning is discussed in detail.Simulations demonstrate that the stability of the range profile to target-radar attitude has been improved by fusing multi-aspect range profiles,which lays a foundation for further processing of feature extraction or target recognition.