Attitude Estimation And Active Disturbance Rejection Control For Quadrotor UAV

When UAV working,we need to know the accurate attitude of UAV.Therefore,it is necessary to estimate the attitude information of UAV in real time.In practice,there will be a drift caused by the MEMS gyro sensor which will cause attitude divergence;When the quad-rotor flying especially in the acceleration,the body of quad-rotor will violently vibrate,which will affect the accelerometer in the form of white noise;The magnetometer is easily affected by the external magnetic field in the working process.The above reasons will lead to the attitude information is not accurate finally.At the same time,The following features of the system are difficulty of designing control system:coupling relation between the multiple variables of the system,the uncertainty of system model,and it is very easy to be influenced by the unknown external disturbance.In order to solve the above problems,we use the extended Kalman filter algorithm based on quaternion and the gradient descent method based on quaternion to estimate the attitude of quad-rotor UAV.We also use the active disturbance rejection control technique to control the attitude system of the quad-rotor UAV in this thesis.First of all,the research background and significance of quad-rotor UAV are expounded.The current research situation of quad-rotor UAV and the research status of the main technologies are introduced.The main methods of attitude calculation and attitude control for quad-rotor UAV are analyzed.Secondly,the basic knowledge of quad-rotor UAV is introduced.The basic structure of quad-rotor UAV is introduced,and its flight principle is introduced briefly.Describes the quad-rotor UAV common attitude representation method.in order to describe the movement of the quad-rotor UAV,a body coordinate system and the ground reference frame are built,and estalish the dynamics model of the quad-rotor UAV.Thirdly,an extended Kalman filter algorithm based on quaternion is proposed to solve the attitude of quad-rotor UAV.The simulation results show that the algorithm can realize attitude calculation and suppress white noise.Then,the gradient descent method based on quaternion is proposed to solve the attitude of quad-rotor UAV.the simulation is made to validate the algorithm,this algorithm can accurately show the attitude information of the quad-rotor UAV.Finally,because of the difficulty of quad-rotor UAV's attitude system.We design a Active Disturbance Rejection Controller,the simulation results show that this method can realize the control of the quad-rotor UAV attitude,and has strong anti-jamming ability.