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Autonomous Orbit Estimation for Regional Navigation Satellites

Memaran, Mohsen | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45717 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Asadian, Nima
  7. Abstract:
  8. In this thesis, autonomous orbit estimation of regional navigation satellites has been investigated. Estimation of satellite orbit is an integral part of satellite navigation, which may be executed via assistance of ground station. As the satellite is exposed to the ground station view, range, direction and rate of range is measured by mean of ranging instrumentation relative to ground reference, hence the precise position is calculated. In this thesis a set of satellites are investigated in a unique structure called constellation with the purpose of navigation. The occurrence which is likely to happen in this condition, is the failure of ground station under certain circumstances or losing the satellite visibility, conditions under which the satellite orbit estimation won’t be feasible. Owing to the multitude of satellites, their relative information can be utilized to estimate the satellite orbit. Therefore this will be the focus of this research. Since this kind of estimation is independent from ground station, it is technically called Autonomous Estimation. The relative information discussed consists of relative range, relative direction and the rate of relative range between satellites. The dynamics model of the system is based on two sets of equations: Gauss and Cowell, which are compared with each other in simulation section. The estimation is also conducted using extended and unscented Kalman filters in order to choose the appropriate filter. Sensitivity analysis of results with respect to orbital elements and also with respect to the measuring sensors’ accuracy are among the accomplishments herein; with the results of the first analysis it is possible to define a approperiate constellation for regional navigation in applied cases. Eventually, the estimation resulted from the filter is improved by Smoother
  9. Keywords:
  10. Extended Kalman Filter ; Unscented Kalman Filter ; Gauss Equation ; Regional Navigation Satellites ; Autohomous Orbit Estimation ; Relative Position ; Cowell Method

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