Research On Tracking, Orbit Determination Of Target And Routing Algorithm Of Network Conditioned On Space-based Observation

By using optical sensors on orbiting platforms, the space-based optical surveillancesystem has the capabilities of detecting, warning, tracking and cataloging space targets.The world’ powerful nations focus on developing space-based optical surveillancesystem in the field of aerospace, since this system has some attractive advantages suchas wide detection area, far surveillance distance, not suffering from geographicconstraints, and so on. The tracking and orbit determination technologies for spacetarget, and the routing technology for space-based network conditioned on space-basedobservation play key roles in the information processing and transmission of thespace-based optical surveillance system. This paper investigates the low-Earth-orbit(LEO) multi-target tracking and the short-arc orbit determination of high-Earth-orbit(HEO) target using space-based observations, and the routing algorithm of space-basedLEO network. The main contributions of this paper are as follows:1. Random finite set theory based LEO multi-target tracking using space-basedobservationsFor tracking of LEO multi-target on space-based focal plane, a method of Gaussianmixture cardinalized probability hypothesis density (GM-CPHD) filter is given. Thismethod estimates the number and the target states on the focal plane by usingGM-CPHD filter, and then generates target tracks on the focal plane by using themethod of minimum weighted matching. Simulation results show that the GM-CPHDfilter method outperforms the GM-PHD filter for the estimation accuracy of targetnumber, and that the target tracks can be generated almost exactly.A multi-Bernoulli smoother for tracking of LEO multi-target on space-based focalplane is proposed. The smoother is desired to improve the performance of trackingmethod based on the filter. For the multi-Bernoulli smoother, the backward recursion ofthe smoothed multi-target probability density is derived by using the method ofmulti-Bernoulli approximation, and the computational problem of multiple integrals issolved by using sequential Monte Carlo method. Simulation results show that thesmoother can dramatically improve the estimation accuracy of target number and targetstates over the filter.For3D tracking of LEO multi-target using space-based observations, a multiplemodel CPHD filter is proposed. This filter constructs multiple motion models for LEOtarget. The augmented state is established by combining the target state with the targetmotion mode. Both the posterior cardinality distribution of targets and the posteriorPHD of the augmented state are propagated by using CPHD filter. The target numberand the target3D states are jointly estimated. Simulation results show that the multiplemodel CPHD filter outperforms the single model CPHD filter and the multiple model PHD filter.For the self-calibration of systematical error of sensors in space-based LEOmulti-target tracking problem, an extended CPHD filter is proposed. This filterestablishes extended state by appending the sensor biases to the target state. Both theposterior cardinality distribution of targets and the posterior PHD of the extended stateare propagated by using CPHD filter. The number and the states of the targets and thesensor biases are jointly estimated. Simulation results show that the extended CPHDfilter successfully achieves real-time estimation and alignment of the systematical error,and outperforms the standard CPHD filter.2. Short-arc orbit determination method for HEO target conditioned on LEO singlesatellite observationWe give two methods of orbit determination using two adjacent short-arcs ofangular measurements. The first method constructs admissible region by using theenergy constraint of two-body orbit. The admissible region of the first arc is sampled bytriangulation. Comparing these samples with the second arc, several proper orbits ofthese samples are determined as initial orbits. These initial orbits are all used for orbitimprovement. Simulation results show that this method can successfully achieve theleast square solution. The second method establishes energy and angular-momentumconservation equations of two-body orbit using two short arcs of angular measurements.Multiple solutions of these equations are obtained via variable transformation. Theoptimal solution is selected by covariance analysis, and is used for computing the initialorbit. This initial orbit is used for orbit improvement. Simulation results show that thismethod can derive initial orbit without any prior information about the orbit of spacetarget. The orbit improvement can successfully achieve the least square solution,indicating the excellent convergence behavior.3. Routing algorithm of space-based LEO networkA multi-constrained optimal routing algorithm is proposed. This algorithmestablishes the multi-constrained optimal path (MCOP) model, whose constraints aredelay, hop-count and available bandwidth and objective is to optimize the performanceof handover, delay and bandwidth utilization. The computational amount of findingMCOP is reduced by decreasing the searching field of feasible solutions. Simulationresults show that the routing algorithm is superior to other current algorithms in theaspects of computing complexity and handover performance, indicating the adaptabilityfor on-line routing.