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Spacecraft Planet Landing Control Based on Dual Quaternion

Hazrati Azad, Mehdi | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49759 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Asadian, Nima; Ghanbarpour Asl, Habib
  7. Abstract:
  8. In this study the problem of position and attitude control of a Spacecraft has been investigated under position and attitude constraints as well as uncertainties in mass, moments of inertia, thrust vector error, and external disturbances. The Lyapunov theory is utilized for deriving the appropriate controls. Two kinds of controls are derived in the first step. The first kind has been derived using direct Lyapunov method and the second by the use of back-stepping method. Obtained simulation results prove that the first control scheme is more suitable for a Spacecraft control, since it has less computational effort, convenient selection of control parameters, and especially it has less complexity to deal with constraints representation. The dual-quaternions are used to derive the kinematic equations. The position and attitude kinematic equations in the form of dual-quaternions simplify to a unit pseudo-linear equation. In the next step, the constraint equations are introduced in an exponential form. An exponential function creates a high potential region (constraint area) in the Lyapunov function, so it prevents the states entering the constraint area. This constraint modelling method, helps to have better localizations in the state space of the system as well as preventing singularity problems in the constraint area. Simulation results show that the proposed equations satisfy the constraints, and consequently prevents the Spacecraft to lie in inappropriate attitudes or positions. Finally, the control parameters in the Lyapunov method has been derived in order to the system become robust in presence of uncertainties in mass, moments of inertia, thruster errors, and external disturbances (drag). Results show that the control purposes (arriving to the final states, satisfying position and attitude constraints) are satisfied
  9. Keywords:
  10. Robust Controller ; Spacecraft Guidance ; Lyapunov Stability ; Dual Quaternion ; Position and Attitude Constraints ; Position and Attitude Control

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