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Dynamic Modelling and Nonlinear Control of a Hybrid Powered Hexarotor for Precise Trajectory Tracking

Saadat, Sepehr | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53464 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Nobahari, Hadi
  7. Abstract:
  8. In this Thesis, an unmanned multicopter with a new structure is modeled and a nonlinear controller is designed for it to track the trajectories precisely. The multicopter in this thesis, has six propellers with a hybrid propulsion system (a combination of fuel and electric propulsion system) that has the ability to carry more payload and maintain more flight duration compared to electric multicopters. In the beginning, the performance characteristics and technical specifications of the hexacopter are presented. For modeling, first the equations of six degrees of freedom movement of the hexacopter are derived by the Newton-Euler method. In the next step, the forces and torques applied to the hexacopter, including the aerodynamic drag force and torque and the propulsive force of the propellers and the resulting torque, are investigated. The BEMT method is used to calculate the propulsive force and torque of the Propellers. To calculate the aerodynamic drag force, a simple model is chosen, in which the amount of drag force is directly related to the square of the relative velocity of hexacopter and air. Also, the fuel consumption and dynamics of the piston engine and electric motors are modeled using simple relationships. The effect of wind turbulence, turbulence due to piston engine vibrations and sensors noise on the hexacopter flight is also investigated. Then, after reviewing the common nonlinear control methods and based on the characteristics of the controlled system, the Backstepping control method is selected. After designing the controller using the Backstepping method and applying it to the system, the controller performance is evaluated in a number of scenarios and compared with the performance of the PID feedback linearization controller. The simulation results show that the Backstepping controller has a perfect performance in controlling the hybrid hexacopter and has high robustness to disturbances, noise and model uncertainties
  9. Keywords:
  10. Blade Element Momentum Theory ; Multiple Input-Multiple Output (MIMO)Controller ; Nonlinear Control ; Dynamic Modeling ; Back-Stepping Method ; Hybrid Hexarotor ; Trajectory Tracking Control

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