Research On Non-cooperative Target Tracking Algorithms And Related Technologies Using Space-based Bearings-only Measurements

The surveillance of space objects is the important approach to obtain national space stratagem information. The space-based bearings-only tracking and orbit determination technology for non-cooperative space target (NCST) is a critical technology for realizing and establishing our space-based surveillance system. In this dissertation, we stress on researching the initial orbit determination, tracking filter, combined orbit determination, robustly adaptive tracking, and space objects catalog maintenance and so on. We make full use of some mathematical tools including parameter estimation theory, homotopy continuation theory, observability theory of nonlinear control system, nonlinear filter theory, federated filter theory, and robust estimation theory to carry out the research on the key technologies. This dissertation adopts the combination of simulation test verification and mathematics reasoning as the research strategy so as to insure the correctness of models and algorithms researched above. Some key problems have been solved basically for the space-based bearings-only tracking technology of space objects in this dissertation. The main works are as follows:The technologies of short-arc initial orbit determination (IOD) with space-based bearings-only measurements. (1)Two methods of initial iteration values selection in short-arc IOD are proposed that are the simple iteration algorithm considering the J 2 perturbation and the trust region algorithm based on the conventional Gauss method. (2)Based on the improved Laplace method and the unit-vector-method of perturbation orbit, the homotopy continuation theory is introduced into the short-arc IOD method. Then the initial orbit of the NCST with the single satellite observation and two-satellite formation observation can be determined by the presented method.The observability analysis method of the space-based bearings-only tracking system. (1)According to the state equations and measurement equations of the space-based bearings-only tracking system, the observability analysis method is proposed based on the observability theory of nonlinear control system. And the observability of the single satellite with near circle orbit to NCST bearings-only tracking system is proved. (2)The CRLB theory and system observability degree are introduced to describe the relative strength of the system observability, and the influencing factors of the system observability degree are analyzed with simulation results.The technologies of distributed satellites to NCST combined orbit determination. (1)Based on fusion of ground-based observations, inter-satellite measurements and NCST bearings-only measurements, the integrated real-time orbit determination with SR-UKF algorithm is proposed. (2)The generalized federated SPIF algorithm is presented based on distributed sigma-points information filtering, and the method is designed to solve the problem that the master filter dimension does not equal the local filter dimension. Then the information sharing principle with"condition resetting"is used to ameliorate the efficiency of data-processing and fault tolerance.The robustly adaptive filter algorithm of the space-based bearings-only tracking system. (1)Considering the EKF declines in performance when the kinematic state disturbing and measurement outliers,the robustly adaptive EKF algorithm is proposed, and the algorithm combines the noise statistic estimator and adaptive factors to balance the contributions of observation data and predicted state. (2)Aiming at the traditional UKF declines in accuracy and further diverges when the prior noise statistic is unknown and time-varying,the robustly adaptive filter algorithm is proposed based on maximum a posterior estimation. Then the time-varying noise statistic estimator and adaptive robust factors are combined to restrain the influence of abnormal value effectively, on the other hand, enhance the filter precision and stability. And the performance analysis of the presented algorithm is done based on the stability analysis method of traditional UKF and the CRLB theory.The new two-line elements (TLE) fitting method applied to the space-based bearing-only tracking system. (1)Due to the singularity existence in the iterative approximation procedure, the TLE sampling fitting method is put forward according to the non-singular transformation of orbital elements. (2)The new TLE fitting method introduces the adaptive forgetting factor recursive least-squares algorithm to improve the efficiency of data-processing. Numerical simulations indicate that the method can enhance the iterative rapidity of convergence and the accuracy of forecasting orbit, especially for near-earth space objects.This dissertation investigates systemically the space-based bearings-only tracking algorithms and related techniques. The exploratory research achievements of this dissertation would avail to pave the way for further researches and experiments, and also have certain reference values for our space-based surveillance techniques.