| In traditional TWS(Tacking and Scanning)radar tracking system,antenna returns a mesurement once it detects a target.the radar continuously receives measurements during a scan period.However,traditional tracking algorithms,like multi-hypothesis tracker(MHT),joint probabilistic data association algorithm(JPDA),wait until the end of a scan period before estimating the latest state of the target.This update method may cause significant delay from detecting the target to updating the target ’s state.In addition,this update method assumes that the radar only receives one measurement for each target in each scan period.This assumption may result in trajectory breakage near the scanning boundary.The main scanning modes of TWS radar are circumferential scanning or sector scanning.For circumferential scanning,the tracking delay mainly depends on the position of the target when it is detected.The closer the target is to the position where the scan cycle begins,the longer the tracking delay will be,and the closer the target is to the position where the scan cycle ends,the smaller the tracking delay will be.When the target crosses the boundary of the circumferential scanning,trajectory breakage may arise.If the target’s movement direction is the same as the antenna’s scanning direction,the radar may not receive observations from the target within a period.If the target’s movement direction is opposite to the antenna direction,the radar may receive two observations from the target within a period.However,the traditional tracking algorithm updates target ’s state once a cycle,which will cause the tracking algorithm to be misaligned with the received measurements.If there is a wrong association,the tracking accuracy will decrease.If there is no wrong association,the trajectory will be broken.For sector scanning TWS radar,the antenna constantly changes the scanning direction,and the tracking delay is not only related to the target position,but also related to the antenna ’s scanning direction.In addition,the range of the azimuth angle scanned by the sector scanning radar is limited.When the target crosses the scanning boundary,the sector scanning radar is not able to track it.Therefore,there is no boundary problem in sector scanning radar.In this article,we propose a dynamic update method based on the Linear Multi-Target Integrated Track Splitting(LMITS)algorithm.For the circumferential scanning TWS radar and the sector scanning TWS radar,we have done the following:(1)Research on the uncertainty of revisit interval in circumferential scanning and sector scanning TWS radars,and propose an improved space-time joint state estimation(STJP)method,which builds the foundation for the study of continuous tracking algorithms.(2)To solve the tracking delay and boundary problems in the circumferential scanning TWS radar,a dynamic update algorithm-Continuous Tracking Algorithm(CITS)is proposed.The continuous tracking algorithm places the update timing after the antenna sweeps through the trajectories’ validation gate,which minimizes the tracking delay.In addition,the continuous tracking algorithm ha s eliminated the traditional periodic update method and changed to update according to the trajectories’ validation gate.The update times of the continuous tracking algorithm in each cycle are determined by the actual position of the validation gate,whic h solves the boundary problem.Results of simulation experiments show that the continuous tracking algorithm significantly reduces the tracking delay and improves the tracking accuracy and trajectory maintenance ability of the tracking system when the target crosses the boundary.(3)Based on the single-target continuous tracking algorithm,this research combines the Linear Multi-target algorithm(LM)and the Interacting Multiple Model algorithm(IMM)to propose the multi-target continuous tracking algorithm(LMCITS)and the maneuvering multi-target continuous tracking algorithm(IMM-LMCITS).Results of simulation experiments show that whether tracking multiple targets or tracking maneuvering targets,the continuous tracking algorithm significantly reduces the tracking delay,and improves the tracking accuracy and trajectory maintenance ability of the tracking system when the target crosses the boundary.(4)For the sector scanning TWS radar,after analyzing its scanning modes,this paper researches the problem of revisit interval and tracking delay in the sector scan situation,and proposes a continuous tracking algorithm for the sector scanning TWS radar.Results of simulation experiments show that the continuous tracking algorithm significantly reduces the tracking delay without reducing the tracking accuracy and trajectory maintenance ability. |
