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Optical Flow Based Flight of a Small Fixed-Wing Aircraft in Ideal Urban Environments

Rezaei, Mahdi | 2011

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 42001 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Saghafi, Fariborz
  7. Abstract:
  8. This thesis represents the obstacle avoidance of a fixed-wing small aircraft using optical flow information of cameras mounted on the aircraft. The thesis consists of two main sections. In section one, the ideal optical flow has been simulated based on the camera model, complete six DOF of flight equations, and the geometry of the environment. An analytical formula has been derived to relate the obstacle detection distance to the maneuverability of the aircraft. Having the obstacle detection distance, the control and navigation algorithms have been developed to achieve a collision-free flight for the aircraft in urban canyons and junctions. The effect of some parameters such as approach velocity, optical flow noise, and the rotational optical flow error on the aircraft flight behavior has been studied. Finally and for generalization purpose, an equation has been derived to measure the minimum dimensions of urban canyons based on the navigation algorithm and the minimum turn radius of the aircraft.
    In section two, a virtual graphical framework has been developed to measure the optical flow field using image processing techniques applied on the graphical images. It has been shown that the measured optical flow is very different of ideal optical flow and the environment context has large effects on the magnitude and orientation of the optical flow vectors. To improve the results, a convolution filter is applied to the graphical images as well as a statistical technique for removing of the noises of the optical flow field. The effect of obstacle density of the environment on the collision probability of the aircraft has also been discussed
  9. Keywords:
  10. Aircraft ; Navigation ; Image Processing ; Optical Flow ; Obstacle Avoidance

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