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

With the rapid development of science and technology, great achievements have been made in the research of unmanned aerial vehicle. Variable-sweep wing allows flying carriers to improve flying efficiency under different attitudes by changing swings in real time. Attitude determination method of carriers is a focus in engineering application research, and working out carriers’ attitude with high accuracy by calculating observation data even with noise has always been a difficulty in engineering. At present, strap-down inertial navigation system(SINS) is a critical technique to obtain carriers’ attitude information and using SINS to determine carriers’ attitude is one of the hottest issues in current research both at home and abroad.Based on the analysis and reference of foreign and domestic research on variable wing UAV,this paper starts with detailed introduction of SINS. To be specific, it presents definition of several coordinate systems and coordinate conversions usually used for attitude determination and highlights coordinate conversion between local NED coordinate system and carrier coordinate system. At the same time, it also demonstrates the research into attitude matrix calculation. Exactly, three equations to figure out attitude matrix, namely, Euler algorithm, direction cosine algorithm, and quaternion algorithm, are illustrated. These three basic calculation methods for SINS navigation parameters and the calculation method of attitude angles are analyzed to lay a theoretical foundation for the collection of carrier attitude information.Then, to help to conduct a comprehensive analysis of variable wing UAV flight control system, a small variable-sweep wing UAV flight control system is designed with STM32F103ZET6 as the main controller. Sensors used include MPU6050 sensor which integrates three axis gyroscope and three-axis accelerometer, HMC5883 L three axis magnetometer with low power consumption and so on. Based on the modularization thought, the overall plan of flight control system is designed and sensors of various modules are checked. Then, carrier attitude data, temperature and height are shown in real time through the display module.According to the design of variable wing UAV flight control system,the program of Integrated Navigation can be used in order to get the attitude information more precisely.The last part of this paper is divided into four aspects. First, an outline isgiven about the advantage of determining attitude by combining sensors. Second, the reasons are analyzed as to why gyroscope, accelerometer and magnetometer are combined to determine attitude. Third, PI control algorithm was introduced in brief to illustrate PI control deviation and the collection process of attitude angle by attitude determining systems consisting of several sensors is given. Last, MATLAB simulation is conducted on the attitude data obtained on a three axis platform to give error diagram of attitude angle. It is strongly proved that attitude data for combination navigation is more accurate through the comparison of attitude angle error for combination navigation and gyroscope.