Research On Attitude Control Of Quadroror Aircraft

Quadrotor is a special type of rotorcraft,it has simple structure,easy operation,flexible control.The quadrotor can control the speed of four propellers by adjusting the rotation speed of motors so as to complete some functions,such as vertical take-off and landing,flipping,hover freely and side flight.The quadrotor is a multivariable,strong coupling,sensitivity to outside interference,under-actuated and complex nonlinear system.There is a strong coupling between attitude control and position control of quadrotor,only ensuring attitude stability of quadrotor throughout the flight can guarantee position control would be completed.This paper studies the attitude control problem for quadrotor,the main research work is as follows:Firstly,by studying the structure and control principle of quadrotor,the body coordinate system and the earth coordinate system are selected,the nonlinear models are established based on the analysis of the quadrotor's mechanics and dynamics according to the Newton's second law and the Euler equation.Secondly,after giving the nonlinear model of quadrotor,its representation by a T-S fuzzy model is discussed.A controller is designed to stabilize the attitude of quadrotor based on linear matrix inequality(LMI)state feedback,Simulation results show the effectiveness of proposed controller.Thirdly,a backstepping sliding mode controller is proposed for nonlinear attitude system with model errors and uncertain disturbances.A backstepping method introduces sliding mode,the whole design process shows that the method is not only easy and flexible to solve nonlinear component of the attitude system,but also can eliminate and restrain model errors and external disturbances.The simulation results demonstrate that the attitude-controller has a good control performance.Finally,in order to more accurately describe the actual system,considering actuator fault and the uncertain external disturbances,a robust adaptive fault-tolerant control method for attitude system is presented.It doesn't demand any explicit fault information for control design and improve computing efficiency.The simulation results show that the proposed method has strong robustness to external disturbances and actuator fault.