Research On Bearings-Only Ground Slow Target Localization And Tracking With Unknown Relative Altitude

The missile-borne or airborne passive radar is widely used in milltary and civilian fields because it has the advantages of simple system,long range and strong concealment.For example,during the long-distance guidance,missiles need to achieve bearings-only positioning or tracking of the slow moving targets on the ground.Affected by the curvature of the earth and the irregular terrain,the altitude information of the observer relative to the ground target is unknown.At this time,the estimation result obtained by the traditional single-station bearing-only location and tracking method has a large Error.In this thesis,the positioning and tracking of single observer bearings-only has been studied under the unknown altitude of the observer relative to the target.The main contents of this paper are given as follows.1.Several typical bearings-only ground slow target positioning and tracking algorithms using single observer are reviewed,and the performance of those algorithms is analyzed and compared.It is the basis of the research on the positioning and tracking algorithm of the bearings-only ground slow target for unknown altitude of the observer relative to the target.2.A dimension extended targeting algorithm based on weighted instrument variables is proposed for the bearings-only solw ground target position problem under the unknown altitude of the observer relative to the target.Firstly,the traditional two-dimensional target localization estimation is transformed into four-dimensional parameter estimation problem by modeling the observer altitude variation process.Secondly,a new dimension extension pseudo-linear measurement equation is constructed based on azimuth and elevation measurement equations.Finally,weighted instrumental variable and two-step weighted instrumental variable algorithm are proposed respectively to obtain the estimated value of the target position,the relative altitude of the observer and the target and its change rate.The simulation results show that the root mean square error of the target position,observer altitude and the altitude change rate estimate obtained by the two-step weighted instrumental variable algorithm is closer to Cramér-Rao lower bound than the pseudo-linear algorithm,the instrumental variable algorithm and the weighted instrumental variable algorithm under different measured noise standard deviation.3.An extended Kalman target tracking algorithm based on state correlation is proposed for the bearings-only solw ground target tracking problem under the unknown altitude of the observer relative to the target.The algorithm is used Gauss-Helmert state transition model to establish the constraint relationship between the target position and the relative altitude.The constraint condition relationship is used to solve the problem that the conventional discrete dynamic model is difficult to predict the target state.The simulation results show that the extended kalman target tracking algorithm based on state correlation has faster convergence rate than the traditional Extended Kalman Filter algorithm,and the root mean square error of the estimated value is smaller,and it can approach the posterior Cramér-Rao lower bound.