Research On High Precision Attitude Control Technology For Large Flexible Satellite

With the development of science and technology and the progress of human society,the space industry has developed rapidly in modern times.The space mission is becoming more and more complex,so the attitude control of satellite is required more and more.Therefore,the research on high precision attitude control of large flexible satellite in this paper has important research value and application background.The research contents mainly include the following aspects:In this paper,four commonly used methods to describe the attitude of a flexible satellite with a rigid central body and a flexible appendage are analyzed and discussed,the attitude kinematics equations in Euler angle form and quaternion form are derived based on Euler angles and quaternion theory,and the dynamic equations are established by Joseph-Louis Lagrange analytical mechanics method The modal parameters of the flexible appendages are analyzed by finite element method,and a complete mathematical model of satellite motion is established.Based on the theory of Computer Vision Measurement,the method of flexible vibration measurement based on monocular vision and the method of flexible vibration measurement based on binocular Stereo Vision are studied.Firstly,the model of pinhole camera is established,and the coordinate transformation between the world coordinate system and the image coordinate system is deduced.Secondly,the measurement target is designed,the image is preprocessed,and then the vibration information of the flexible appendage is obtained by threshold segmentation and feature extraction.In order to identify the dynamic parameters of the flexible satellite,the modal parameters and the moment of inertia of the flexible satellite are identified by least squares identification,recursive least squares identification and fading memory least squares respectively.Firstly,the identification model of the parameters to be identified is established according to the satellite attitude dynamics model,and then the simulation model is built to carry out the simulation analysis.Finally,aiming at the attitude control problem of satellite with flexible sails,the classical PID control law and the sliding mode variable structure control law are designed respectively based on the classical control theory and sliding mode variable structure control theory,the control system is simulated and analyzed,and the control effects of the two control laws are compared.The advantage of sliding mode variable structure control in flexible satellite control is verified.