Research On Multistatic Location Of Moving Target Based On Ellipse Distance And Doppler Frequency

In the sonar system,estimating the position and velocity of the moving target is a very important research topic.The sonar system estimates the position and velocity of the moving target by measuring the target signal parameters and combining the measured parameters with an effective method.In this paper,we mainly aim at the estimation of the position and velocity of the moving target based on the ellipse distance and the Doppler frequency measurements.This paper mainly studies the following three aspects.(1)This paper investigates the model of localization system based on ellipse distance and Doppler frequency measurements,then the ellipse distance and the Doppler frequency equations of the model are provided.What's more,we compare the Cramer-Rao lower bound(CRLB)of the sonar positions accurately known with the CRLB of the sonar positions with random errors.(2)An improved Weighted Least Squares(WLS)localization algorithm based on ellipse distance and Doppler frequency measurements is proposed to analysis the influence of the sonar positions with random errors on localization performance of a multi-static sonar localization system.Firstly,the improved WLS algorithm transforms the nonlinear measurement equations based on ellipse distance and Doppler frequency measurements into pseudo linear equations about position,velocity and intermediate variables,and the initial estimation of target position and velocity is attained by WLS method.Then,the estimation error of target position and velocity is estimated by using the pertinence between position,velocity and intermediate variables.Finally,the initial solution of the position and velocity of the target is corrected by the error estimate.The statistical validity of the proposed algorithm is analyzed under the condition that the measurement error is small.(3)A new localization algorithm based on second order cone programming(SOCP)and Taylor series(TS)expansion is used to solve the problem that the estimated performances of the multi-step WLS method and the improved WLS method can not achieve the CRLB of localization problem well when the observed noise variance is large.Firstly,the algorithm relax the localization problem for getting a SOCP problem and solve the optimization problem by using the interior point algorithm.Then,the value of the target position is used as the initial value of the TS expansion to carry out the TS expansion iterative operation.The simulation results show that the estimated performance of the proposed method can achieve the CRLB well in case of low noise level and high noise level without considering the location error of transmitting and receiving equipment.