Research Of Flight Control System And Attitude In Variable-Wing Unmanned Aerial Vehicle

With the rapid development of modern science and technology,great progress has been made in the research of UAV.By using the variable sweep wing technology in UAV,the wing’s back sweep Angle can be changed in real time for different flight missions and flight environments,so that the flight efficiency in different flight states can be improved.Susceptibled to a variety of environmental factors,the flight attitude of a UAV is easy to be disturbed when performing airborne missions,which will affect the mission implementation rate in the end.Therefore,it is crucial to obtain highprecision UAV attitude data from noise-containing ones and perform real-time attitude control.At present,the research at home and abroad mainly focuses on the measurement of UAV attitude with the technology of strapdown inertial navigation system(SINS),which is an important means for obtaining UAV attitude information.Combined with the Kalman filter algorithm the strapdown inertial navigatin system technology is used to obtain hogh-precision attitude information.In this project,the variable backward sweep wing technology is adopted in UAV,mainly aiming at the attitude relatd issues of variable wing UAV,and then the corresponding software and hardware of variable wing UAV are designed,and the switching control system of variable wing UAV is also studied.This paper first describes the development status of variable-wing UAV at home and abroad,and then introduces the SINS technology and the principle of attitude measurement in detail.The focus of the part is the research on the calculation method of carrier’s attitude.With the comparative analysis of Euler angle method,direction cosine method,and quaternion method,it is found that the singularity problem will occur when describing the attitude with Euler angle and computational complexity with direction cosine method is too high.Thus,the attitude calculation which based on the attitude angle is obtained by solving the quaternion differential equation through the combination of quaternion method and the fourth-order Runge-Kutta method.Strapdown Inertial Navigation System is used to reduce costs,Simplify repair time and increase reliability,However,the inertial device has its own inherent characteristic problem,the attitude data acquired by using the gyro under static conditions often includes constant error and random offset error,which will cause angle drift in attitude calculation,so it is not suitable for long-time accurate measurement.Similarly,accelerometers will introduce linear acceleration to the calculation when the carrier is in motion and result in inaccurate horizontal tilt(pitch and roll angles).Magnetometers are prone to be interfered by geomagnetic field and lead to errors in the yaw angle.Therefore,Kalman filter algotithm for data fusion is used to obtain the best attitude angle for which the problem can be solved.Then,in order to obtain carrier attitude information,A small flight control system for STM32F407 is designed in this paper.The system is mainly composed of attitude measurement module,GPS navigation module,air pressure measurement module and actuator system.On the hardware device a six-axi MPU-6050 sensor and a sensor such as MAG3110 is used.On the system software structure,the data acquisition function is realized through the drive debugging and testing of each sensor module.Finally,for the convenience of attitude data acquisition and testing,the environment of a three-axis flight simulation platform is choosed.The obtained attitude data is simulated in MATLAB environment.Through the comparison of the combined attitude measurement and the original pose measurement data based on the Kalman filter,it is proved that the pose angle obtained by the combined pose determination solution is better.