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Time Optimal Closed-Loop Attitude Control of Magnetic Actuated Satellites Using Neural Networks

Heydari, Ali | 2008

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39286 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Pourtakdoust, Hossein
  7. Abstract:
  8. Using magnetic torquers as the sole actuator for attitude control of small satellite despite its benefits has a drawback that is lack of controllability. Mechanical torques can be created only perpendicular to the instantaneous magnetic field vector, thus at each time instant the satellite can be controlled only around two axes out of its three perpendicular axes.
    Fortunately because of the satellite motion, the direction of uncontrollable axis changes by time, therefore the sufficient attitude control can be achieved along time. Almost all of the present magnetic attitude control methods need more than one orbital period to control and cause the attitude to converge to the desired conditions, so they are very time-consuming and for missions with time limitation they aren’t beneficial. In this research after describing some fundamental topics related to the magnetic actuated satellites, a time optimal solution is sought which can perform an attitude maneuver of an inertial pointing satellite in a small fraction of an orbit. Using a neural network with time-varying weights as a feedback optimal controller results in a closed-loop optimal attitude controller. Finally the controller has been investigated through Monte Carlo analysis and its good robustness against several disturbances has been depicted
  9. Keywords:
  10. Time Optimal Control ; Air Monitoring ; Dynamic Weighted Neural Network

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