Fault-Tolerant Attitude Control of Satellite with Thrusters Using μ-synthesis

Taheri, Abdolreza | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52951 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Assadian, Nima
  7. Abstract:
  8. In this project, a fault-tolerant attitude control system is developed for thruster-driven satellites. The proposed method has the advantage over current state-of-the-art approaches in that it does not require a fault detection and isolation system. Generalized moments are generated by a robust controller that is designed using mixed sensitivity H_∞ and μ-synthesis by DK-iteration. Moreover, a pulse-width modulation technique with quadratic programming optimization is tuned to map the controller outputs to thruster on-off commands as efficiently as possible. The controller is designed to tolerate up to ±30% perturbations in inertia properties and thrust degradations up to 90% of the nominal values. Effects of external disturbances and measurement noises have also been taken into account. Regardless of the type and amount of variations, neither the controller nor the thruster allocation system are reconfigured. Moreover, robust stability and performance margins for the closed-loop system of the controller and linear dynamics are guaranteed by μ-analysis. Monte Carlo simulation results are provided for the simulation of full nonlinear dynamics in nominal, worst case, and random perturbations. The results are compared with a Lyapunov-based thruster allocation method that show significant reduction in total impulse of the maneuvers and improved performance in terms of steady-state errors for the developed control. Additional analysis is provided to study the effects of each type of perturbation and reference tracking on the performance of the fault-tolerant control system
  9. Keywords:
  10. Fault-tolerant Control ; Attitude Control ; Thruster ; Robust Control ; H-infinity Method ; Satellite Attitude Control

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