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Agile Flight Vehicle Roll Autopilot Design for Reducing Channels Coupling Effects

Rezazadeh Mohammadi, Masoud | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46460 (45)
  4. University: Sharif University of Technology
  5. Advisor(s): Fathi, Mohsen
  6. Abstract:
  7. In this project roll channel autopilot of an agile flight vehicle has been studied. In skid-to-turn tactical flight vehicles according to the type of control strategy, for achievment of acceleration commands, the roll angular velocity should be kept near zero. In usual autopilot design, effects of channels on each others is ignored. But three channels of agile flight vehicles have some mutual effects, that consists of kinematic, inertial and aerodynamic couplings. In the case of roll channel dynamics, aerodynamic couplings are dominant and apears because of two factors: roll induced moment and roll cross coupling moment.
    After study and aerodynamic modeling of mentioned factors, based on control methods used in the literature survey, four different control methods was designed to satisfy roll control objectives. The first method is PI controller that is designed using optimal control approach for simple dynamic model. The second method use previous controller, but for dynamic model that improved by elimination of nonlinar aerodynamic effects. Robust control based on ESO disturbance observer is third method, that estimate composite disturbance enters the system, and compensate it. Finally 4th method is combination of input-output linearisation and UDE robust control.
    Flight simulation results in the presence of various factors affecting the roll channel, show that 2nd and 3rd methods are better than optimal PI. On the other hand, if approximated relations for roll induced moment and roll cross coupling moment have adequate accuracy, control performance of 4th method will be much better than the other three methods.
  8. Keywords:
  9. Interference ; Robust Control ; Observer ; Autopilot ; Roll Channel ; Roll Induced Moment

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