Research And Realization Of Autonomous Flight Control For Multi-Rotor UAV

Multi-rotor UAV(unmanned aerial vehicle)can hover in the air and fly even in narrow areas due to its vertical takeoff and landing,which is also simple and reliable.These features make multi-rotor UAV is widely used in military,civilian and scientific research,such as enemy reconnaissance,anti-terrorism training,power inspection,agricultural protection,etc.In order to fully develop the potential of multi-rotor UAV,it is necessary to improve its control performance and autonomy.We propose the overall design of the multi-rotor UAV based on reviewing the state of major research institutions and the autonomy level,which meets the current needs of us.Firstly,the main components of the multi-rotor UAV,including the mechanical system,the power system and the control system,and the hardware composition and selection of each sub-system are described in detail,taking a six-rotor UAV with 700 mm wheelbase as an example.Secondly,the algorithms are used to estimate the position and attitude estimation,including DCM algorithm,complementary filtering algorithm and EKF algorithm,and their main steps and processes are described.Then,the structure and flight principle of six-rotor UAV are analyzed and mathematical model is established,and the PID controller is designed which is most widely applied in practice.There are many problems in practical applications of six-rotor UAV such as model uncertainties,external disturbances,actuator saturation and so on.We propose a sliding mode control method for six-rotor UAV based on multi-loop control structure.In the position loop and the attitude loop,we design a nonsingular fast terminal sliding mode controller in cooperation with adaptive method for handling uncertainties and disturbances.In the rotate speed loop,we design a sliding mode controller based on the disturbance observer.MATLAB/Simulink simulation verify the proposed control scheme can guarantee fast error convergence.Finally,based on the Pixhawk flight controller which is running APM firmware,the autonomous flight control of the six-rotor UAV is implemented.