Design And Realization Of Flight Control System For A Small Unmanned Quadrotor

Recently, as the small-sized unmanned quadrotor is more and more commonly used in military and civil fields, abundant in-depth research has been conducted on it in every way. Most of the research is focused on the development of the unmanned flight control system with more autonomous authority, and the key point and difficulties lie in the design as well as implementation of reliable flight control algorithm.Regarding the small-sized quadrotor as the research objective, this thesis proposes an integrated development philosophy from design to implementation for the autonomous flight control system applied in the quadrotor based on the accurate model. Specifically, the author deduced the mathematical model for the quadrotor firstly by mechanical modeling according to the flight principles. Secondly, the classic control law was applied in the simulation model in order to predict and identify uncertain parameters in the system. Then based on the consequent accurate mathematic model, the author used Backstepping control algorithm to design the core controller of the quadrotor. Afterwards, the author conducted simulated flight in simulation environment to test the controller, and improved it to meet the requirements of the system. At last, the controller was tested in real flight.This thesis starts with the comprehensive introduction to the research status of small-sized unmanned aircrafts at home and abroad. Based on the analysis on current industrial development, the author proposes the research direction and contents of this thesis. Following the order from modeling to parameter identification and controller designing as well as the order from simulation experiments to physical experiments, the author carried out the work as follows. Firstly, the author made elaborately deduction on the motion model and dynamic model of the quadrotor by mechanism modeling, and developed the switching strategy for flight modes. Secondly, based on the model parameters of the double-loop PID verified in low-speed mode, the author deducted parameters of the system to make it closer to the actual model. Due to the nonlinearity, underactuation and multi-coupling of the quadrotor, the author designed the autonomous flight controller by Backstepping control algorithm and demonstrated its stability under Lyapunov meaning. Then under the MATLAB/Simulink simulation environment, the author verified the control algorithm in attitude control and trajectory tracking by simulation experiments. At last, in order to examine the effectiveness of the controller, experimental analysis as well as flight tests was carried out on the controller after it was deployed in the actual quadrotor.Taking the method that is successfully applied in engineering practice as the guidance, the author deducted parameters of the system backwards, designed and experimented the flight controller in strict accordance with the development philosophy which is based on the accurate model, and successfully designed an autonomous flight control system which was assisted by fractional order PID with the core of Backstepping controller.