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Satellite Attitude Control by Limiting Velocity of Reaction Wheels

Shayestehmanesh, Saeed | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45305 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Namvar, Mehrzad
  7. Abstract:
  8. The satellite attitude control problem is to determine the torque that is produced by actuators in such a way that, the satellite reaches to a desired final state from an initial state. If we do not consider the structural and dynamical equations of actuators and its effects in the system’s equations, the control problem is simple and can be solve easily. But, when the dynamic of the actuators and practical constraints associated with them and the equations of the system are to be considered, due to the dependence of these equations, solving the satellite attitude control is not simple like before. That is why, no effective method is presented to solve it. One of the most widely used actuators in the satellite attitude control is reaction wheels. These wheels, Due to its high accuracy, low weight and the fact that they need no fuel, have been highly regarded by the satellite designers in recent years. But because of the velocity saturation of the reaction wheels, satellite designers cannot merely rely on reaction wheels, and they need to add some other elements in order not to allow the wheels to get saturated. Hence, presenting some methods to include wheel’s constraints, in addition to the satellite attitude change, seems to be very important.
    In this thesis, the problem of the satellite attitude control by controlling the velocity of the reaction wheels is studied. Innovation of this thesis in satellite modeling is such a way that, kinematic and dynamic of the satellite is both considered. Under this type of modeling, the problem is converted to a system with Non-holonomic constraints. Existence of Non-holonomic constraints doesn’t allow us to control the system directly, and consequently necessitates the path planning at the beginning. Thence, in this thesis, extended bi-directional method is proposed. Afterwards, two methods are proposed to control the satellite attitude in addition to control the velocity of the reaction wheels
  9. Keywords:
  10. Control ; Satellite Attitude Control ; Attitude Control ; Reaction Wheel (RW) ; Bidirectional Routing

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