| UAV is widely used in agriculture,military,commerce,life and other fields because of its simple body,easy manipulation,flexible flight and other advantages.Among them,the six-rotor UAVs can be used in more extensive and flexible fields because of its stronger load capacity,greater battery capacity,stronger anti-interference ability,and applicable to more dangerous and complex flight missions.However,the six-rotor UAVs has the nonlinear characteristics of input dead zone saturation,unknown control direction and unfavorable factors of actuator failure in the flight process.It is particularly important to study the position and attitude control of UAV through intelligent control algorithm.The main work of this thesis is as follows:First of all,the research background of six rotor aircraft at home and abroad is introduced,and the research significance and current development status of the aircraft are deeply explored.The impact of three adverse factors on UAV flight control and the research status in the field of UAV control are introduced respectively.The intelligent control algorithm used in this thesis is introduced.This thesis systematically describes the structure of the whole thesis and the main work to be completed.Secondly,through the introduction of the flight principle,the flight mode of the aircraft is known more clearly,so that the kinematics model of the aircraft is established,which lays the foundation for the subsequent controller design.Thirdly,considering that the input of the six-rotor UAVs has both dead zone and saturation,the dead zone saturation of the input is converted to linear by indirect transformation,and then the controller is designed for linear input to achieve stable control of the aircraft,and make the position and attitude of the aircraft run along the desired trajectory,thus achieving the control goal.Then,on the basis of the six-rotor UAVs input with dead zone saturation,considering the influence of the unknown control direction on the aircraft system,the vector product method is used to simplify the unknown control function items,and then the positive integrable function and adaptive rate are used to design the controller,so as to finally solve the problem of the influence of the unknown control direction on the UAV system and achieve the flight control goal.Finally,on the basis of the six-rotor UAVs input with dead zone saturation,considering that the actuator has unknown,time-varying and unpredictable actuator failures,Nussbaum gain method and instruction filtering backstepping method are used to design a finite time instruction filtering backstepping controller to avoid the impact of actuator failures on the system.The instruction filtering backstepping method can avoid the complexity explosion and singularity problems caused by repeated differentiation. |
