Orientation Parameters Determination Of The Navigation Satellites Constellation Via X-ray Pulsars Measurement

Traditional methods of orbit determination in the Global Navigation Satellite Systems(GNSS) rely extensively on ground-based operations. This working mode not only increases ground stations’ burden and maintenance expenses, but also lacks long-term auto navigation capacity. In this dissertation, the author focuses on the theory and methods of using the orientation measurement of the baseline vector in the satellites constellation to solve for the satellites constellation rotation, the theory and algorithm of the constellation orientation parameters determination via X-ray pulsars measurement, optimization methods of the schemes of the constellation orientation parameters determination via X-ray pulsars measurement, designing the hardware-in- loop simulation system. The main results achieved in this dissertation are summarized as follows.The theory and methods of using the orientation measurement of the baseline vector to solve for the satellites constellation rotation are systematically studied. For the non-coplanar satellites or coplanar satellites, autonomous navigation method of the satellites constellation based on the inter-ranging measurement is studied. The satellites constellation rotation is described by the constellation orientation parameters, and the theory and methods of using the orientation measurement of the baseline vector to solve for the satellites constellation rotation are systematically studied.The theory and algorithm of the constellation orientation parameters determination via X-ray pulsars measure ment are proposed. Referencing the method of baseline orientation measurements, double measurements plan in a baseline and one measurement plan in a baseline via X-ray pulsar(s) are proposed. Orientation measurement models are built by simplifying the X-ray pulsars relative measurements. Using partial derivative of the measurements, the feasibility of the measurements is analyzed. And those new methods are proved by the Piece-Wise Constant System(PWCS) observability theory.The measurements and the d ynamic models are combined in the UKF filter and federated Kalman filter. The post Cramer-Rao is deduced to acquire the system theoretic precision. Through the numerical simulation and theoretical derivation, the orientation accuracy factors are analyzed.Optimization methods of the constellation orientation parameters determination sche mes are proposed. To the known satellites constellation, the genetic algorithm(GA) is adopted for the baseline optimization. In the optimization plan, optimization variable is the serial number of the satellites, and the orientation precision is the individual fitness function to build the optimization model.When the baseline is confirmed, the sequence quadratic programming is adopted, the three direction of the pulsar are the optimization variable, the target function is the orientation precision to seek the best direction for the given baseline, and then looking for the nearest pulsar to the best direction.The hardware-in–loop simulation system is built for the orientation parameters determination. The plan of the hardware- in- loop simulation system is built. The detector and measurement system in the simulation system is the key study in this chapter. A silicon drift detector(SDD) is used to measure photon energy and arrival time. This system acquires the energy resolution and arrival time information of photons at the same time. In particular, when background noise with different energies disturbs epoch folding, the system can acquire a high signal-to-noise ratio pulse profile. Ground test results show that this system can be applied in autonomous navigation using X-ray pulsar measurement as payload.