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Position and Attitude Control for a Quadrotor Using Nonsmooth Feedback

Mirshamsi, Alireza | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48760 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Namvar, Mehrzad
  7. Abstract:
  8. In recent years, autonomous unmanned aerial vehicles (UAVs) have attracted considerable amount of interest because of a wide area of applications and a lot of advantages. UAVs have been extensively used for military operations that include tracking, surveillance, active engagement with weapons and airborne data acquisition. UAVs are also in demand commercially due to their advantages in comparison to manned vehicles. These advantages include lower manufacturing and operating costs, flexibility in configuration depending on customer request and not risking the pilot on demanding missions. Quadrotor, which is a kind of rotary wing UAVs, has many advantages such as the vertical take-off and landing, hover capability, high maneuverability, and agility. Quadrotors generally use two pairs of identical fixed pitched propellers; two clockwise and two counter-clockwise. These use independent variation of the speed of each rotor to achieve control. By changing the speed of each rotor it is possible to specifically generate a desired forces. The quadrotor is a typical under-actuated, non-linear coupled system. The number of individual manipulating variables cannot instantaneously set the accelerations in all directions of the configuration space. The design of a flight control system capable of not only stabilising attitude but also tracking a trajectory accurately for an under-actuated quadrotor aircraft is quite challenging. but there is many studies that work on this issue. In last studies, for large initial position errors, there is a probability that the attitude feedback be vague and therefor the total system be unstable. In this thesis, we propose a trajectory tracking control design algorithm, based on saturated functions, using a back-stepping approach, which solves the mentioned problem. The obstacle avoidance or collision avoidance problem is an important issue for UAVs. In the previously studies, the combine of two problems i.e. trajectory tracking and obstacle avoidance is not considered simultaneously. Actually, common methods, don't guarantee oscillation avoidance or chattering avoidance. In this thesis, we propose a method that guarantee obstacle avoidance and asymptotic stability (for regulation case) simultaneously by using saturated functions. Numerical simulations are performed to demonstrate the performance of the proposed algorithm
  9. Keywords:
  10. Nonlinear Control ; Obstacle Avoidance ; Quadrotor ; Collision Avoidance ; Unmanned Aerial Vehicles (UAV) ; Saturated Controller

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