Small Unmanned Helicopter Modeling And Robust Flight Control

As a highly intelligent aircraft,the small unmanned helicopter can replace human to complete various difficult tasks,and it has a wide range of application in both civilian and military field because of the characteristics of small size,strong concealment and flexibility.With the development of science and technology,small unmanned helicopter has become the focus of research all over the world.Thesis focuses on the modeling and robust flight control of small unmanned helicopters,and the main contents and results are shown as follows:Firstly,the nonlinear and linear models of a small unmanned helicopter are established.The force on the small unmanned helicopter is analysed,and the nonlinear model is obtained by the relationship between the force,torque and the movement of the small unmanned helicopter.The nonlinear model is linearized by the method of small disturbance linearization,and some parameters in the linear model are given by measurement and calculation.Secondly,the identification platform of the small unmanned helicopter is built,and the model parameters are optimized by the system identification.Through the design of software and hardware,the attitude date of small unmanned helicopter is collected,filtered,calculated,transmitted,etc.The ground station system is designed to acquire and record the attitude date,and the model parameters is optimized by the fitting of amplitude-frequency characteristic curve.Then,focusing on the disturbance of small unmanned helicopters,the H_? robust controller based on extended state observer is designed,and based on this,a trajectory tracking controller is designed.In order to track the angular rate and to suppress the disturbance,extended state observer and the robust control method is combined.On the basis of good rate control,PID control method is used to track the trajectory.The effectiveness of the method is verified by simulation.Next,focusing on the uncertainty of system modeling and the oscillation problem in the stabilization process,a stabilization controller with the imaginary limited of the closed-loop pole is designed.The oscillation of the small unmanned helicopter can be reduced during the stabilization process by limiting the range of the imaginary part of the closed-loop pole.The effectiveness of the method is verified by simulation.Finally,for the external disturbance and the oscillation problem during tracking reference system,a H_? robust controller based on imaginary limited of the closed-loop pole is designed.In order to tracking the reference system,the imaginary limited of closed-loop pole and the H_? robust control method is combined to design the controller.This control method can reduce the oscillation during the tracking process and to make the system become more robust to external disturbance.