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Attitude Control of Flexible Satellite using CMG in Slew Maneuver Considering Bending and Torsion Deflections

Faghihi Nia, Ali | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45246 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Asadian, Nima
  7. Abstract:
  8. In this thesis the attitude dynamics, simulation and control of a flexible satellite with CMG (Control Moment Gyro) actuator in three-dimensional slew and rest-to-rest maneuvers have been studied. The flexible satellite is modeled as a rigid hub and two flexible appendages. The bending and torsion of the flexible panels have been considered. The equations of motion have been derived using the Lagrange method and assumed-modes approach is utilized for converting the partial differential equations of structural dynamics into an ordinary differential equation set. The MATLAB and SIMULINK software has been used for simulation and validation of the equations of motion. The simulation and control software is designed such that it can get inputs of the satellite geometrical and physical characteristics. The designed control methods can guarantee the stability of the flexible satellite and conduct the satellite to the desired attitude in reasonable time. On the other hand, the designed control approaches cannot reduce the structural vibrations. The Lyapunov-based control is the only method that suppresses the structural vibrations, because it is the only method uses the feedback of generalized coordinates. After modeling the CMG dynamic on the flexible dynamics control, it has been shown that the structural flexibility and CMG singularity can move the satellite from desired state and force it to the high angular rates. Introducing the proper steering law and using optimal CMG angular velocity vector trajectory, the CMG singularity has been avoided and structural vibration has been less excited
  9. Keywords:
  10. Attitude Control ; Flexible Satellites ; Control Moment Gyro (CMG) ; Slew Maneuvering

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