| With the advantages of simple structure,high maneuverability and flexibility,the quadrotor Unmanned Aerial Vehicle(UAV)has been widely used in military and civil fields.However,the quadrotor has characteristics of nonlinearity,underactuated feature,strong coupling and sensitive to internal and external disturbances.In this case,it’s a big challenge to design the underlying flight controller.Meanwhile with the expansion of applications,to improve the stability and autonomy of the quadrotor,trajectory tracking and smooth trajectory generation in 3d space are also urgent issues needed to be discussed.Aiming at solving above problems,this thesis mainly studies the design of flight controller and algorithms of trajectory generation.Firstly,the model of the quadrotor and low-altitude wind field are established by means of theoretical modeling,and then the model of Bebop Drone is parameterized.The mathematical model can accurately describe dynamics and basic movements of the quadrotor.The model of low-altitude wind field can describe the outdoor flying environment.Secondly,under effects of wind disturbances,based on the model of Bebop Drone,two flight controllers are designed,namely the improved cascading PID controller and the new nonlinear domination controller.Then numerical simulation experiments are conducted in MATLAB.The experimental results indicate that the two designed controllers are able to stabilize the quadrotor system well,and the performance and accuracy of controllers are improved.Thirdly,based on Bebop Drone which is open sourced,a simple and easy to implement position controller is designed,and system identification and flight experiments of trajectory tracking are performed.The model with system identification fits the actual system well,and model prediction errors are significantly small.The parameters of the position controller are easy to adjust and it has a good performance to reduce errors.Finally,under the condition of barrier-free and discrete waypoints,three kinds of algorithms of smooth trajectory generation which satisfy the dynamic constraints are designed and discussed.In practical applications,it is necessary to take demands and the complexity of calculation into consideration and then select the appropriate trajectory generation algorithm. |
