Research On Near-earth Target Location Algorithm Based On Spaceborne Observation Platform

This thesis starts from the related research of positioning algorithm based on single satelliteborne observation platform,and expands to the positioning research based on multi-satelliteborne observation platform.In addition,the research is carried out in terms of the calculation of positioning equation,the filtering of noise and measurement error,the improvement of positioning accuracy,the reduction of positioning cost and the influence of different measurement parameters on positioning accuracy.A new algorithm is proposed and a simulation experiment is designed to verify the existing problems,which provides theoretical guidance for the practical application of positioning system based on spaceborne observation platform.Specific research contents are as follows:Based on single carrier observation platform positioning method of measuring Angle(Angle of arrivals from the AOA)the earth is spherical model ignores the non-uniformity of the earth’s surface to close to the influence of the radiation source target positioning accuracy,this thesis introduced the WGS-84 specification under the model of the earth,through the transformation between the coordinate system combined with a localization algorithm got near source target in three-dimensional space is accurate description,evaluation index and calculate the error CRLB and GDOP.Simulation experiments were designed to verify the influence of different Angle measurement errors on positioning accuracy.When the Angle measurement accuracy is 0.1°,the positioning accuracy of AOA positioning method can reach 500 m.Considering the measurement error and noise interference in the AOA positioning process,EKF algorithm and UKF algorithm are introduced,and the mathematical models of the two algorithms for locating near-earth objects in two-dimensional space are given.In addition,aiming at the limitations of complex covariance matrix calculation and non-stationary terms in the system,ARIMA model was established and transformed with the state space of the positioning system,and ARIMA-UKF algorithm was proposed.Under the same simulation conditions,for the near-earth target positioning algorithm based on a single spaceborne platform,the ARIMA-UKF algorithm has the smallest relative error and the best positioning effect when the final convergence tends to be stable,followed by the UKF algorithm and the EKF algorithm.The observation system is extended from a single spaceborne observation platform to a multi-spaceborne observation platform,and the Time Difference of Arrival(TDOA)algorithm,Chan algorithm and Taylor algorithm are studied to solve the TDOA positioning equation.Aiming at the problem that the Taylor series expansion method relies too much on the initial value to select the appropriate degree,the position of spaceborne observation platform is understood as the constraint condition,and then a Taylor optimization algorithm based on Lagrange constraint factor to modify the initial value of iteration is proposed.Under the same simulation conditions,the simulation results show that the mean square error of the optimization algorithm proposed in this thesis is smaller than that of the traditional Chan algorithm and Taylor algorithm,and it has better solving effect.In order to explore the influence of different parameters on the positioning accuracy,a simulation experiment is designed.The experimental results show that when the near earth radiation source target is 120 km away from the main observation platform,the positioning effect is the best,and the accuracy can reach 193.8 m.In addition,the simulation experiment is designed to analyze the influence of location,baseline distance,sampling frequency,orbit height and other parameters on the positioning accuracy of the double satellite observation platform,which provides a theoretical guidance for the networking mode of the satellite platform in the positioning system.