Determinação de órbita e manobras utilizando GPS e motor com baixo empuxo / Orbit determination and autonomous maneuver using GPS and low thrust

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The Global Positioning System (GPS) is a satellite navigation system that allows the users to determine 3D positioning and the time with high precision. Its main purposes are: aid to radionavigation in three dimensions with high precision positioning, navigation in real time, global coverage and quick acquisition of data sent by the GPS satellites. In this work, it is proposed to estimate, in real time, an orbital state vector composed by position, velocity, bias and drift of the GPS receiver clock on board satellites by processing the raw navigation solution obtained by the on-board receiver. In this work the Kalman filter is used to estimate the state vector based on the incoming observations from the receiver. The Kalman filter is used due to its robustness in real time applications, without unnecessary storage of observations, as they can be processed while being collected. The filter dynamic model includes perturbation due to geopotential, solar radiation pressure and perturbations due to the Sun and the Moon and the observations are the raw navigation solution composed of position and receiver clock bias. Simulations and tests are done using real data from TOPEX/POSEIDON satellite. A comparison is done between the estimated state vector and the precise orbit ephemeris (POE) produced by JPL/NASA. After that an algorithm to convert osculating elements in mean elements and vice versa is implemented because it is required to the orbital maneuvers problem. To perform the orbital maneuvers, a software that calculates an optimal maneuver is developed. This method will be used as a reference for comparison and analises of the suboptimal methods to be used on board. This method id based on an analytical development that generate equations that can be computed in a shorter time, allowing real time applications.

ASSUNTO(S)

determinação de órbita manobras orbitais orbital maneuvers astrodinâmica orbit determination satélites artificiais filtro de kalman

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