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Orbit Determination of LEO Satellites through Combining the SGP4 and HPOP Methods and Magnetic Sensor Data

Sadeghi Boroujeni, Pouria | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45896 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Salarieh, Hasan; Alasti, Arya
  7. Abstract:
  8. Once the satellite is in space, it is very important to make sure that it is in its correct and prescribe orbit, along with the appropriate attitude, at any given point of time. Orbit determination and finding the exact position and velocity of a satellite is one of the most important factors in space missions. The purpose of this work is improvement in orbit determination of LEO satellites. In order to achieve this goal, combination of SGP4 and HPOP algorithms with Kalman filter is used. The HPOP algorithm uses from integration of equations of motion for finding the position and velocity of a satellite. So this algorithm is very accurate for the short time propagation, but since it is highly dependent on initial conditions, a little error in the initial position and velocity results a major error after hours. On the other hand, the SGP4 algorithm does not need any integration and predict the position of the satellite in the orbit by using averaging methods on the perturbed Kepler equations for the motion of satellite. Therefore, error of this algorithm is usually bounded but it has intrinsic error and for the short time propagation, in the most time, the accuracy of HPOP is better than SGP4. So, if these two algorithms is used simultaneously, the data of SGP4 can prevent the HPOP from diverging. In other words, combining these algorithms results in decreasing the errors in propagation of orbit in both of them. In this project, inspiring the combination of GPS-INS, a method for combination of HPOP and SGP4 by using Kalman filter is proposed and an improved HPOP-SGP4 algorithm is introduced. Combination of HPOP algorithm and magnetic data around the earth and using the magnetic sensors in order to reduce the error of HPOP after passing long time from the epoch is another aim of this project
  9. Keywords:
  10. Kalman Filters ; Magnetic Sensor ; Low Earth Orbit (LEO)Satellite ; High Precision Orbit Program (HPOP) ; Simplified General Perturbation (SGP4)

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