Research On Attitude-control System Of Symmetrical Two-stage Reflected SSPS

With the accelerating development of the world and the continuous increase in the number of human beings,traditional energy sources such as oil,natural gas and coal have become increasingly difficult to support the rapid progress of society and science and technology.The reserve of space solar energy is almost infinite,and it is almost unaffected by the weather.99% of the time in a year the orbit in the space can receive sunlight.Therefore,the development of space solar energy is becoming a key research object of the Earth Space Institute.With the continuous deepening of research,scholars at home and abroad have proposed dozens of models of space solar power stations.However,this paper mainly focuses on symmetric two-stage reflective space solar power stations.The system requires maximum illumination efficiency and stable orientation to the ground.In the other word,the condenser mirror of the system should always keep track of the sun and keep the on-orbit attitude of the entire condenser system stable.In response to this demand,this paper studies the satellite's on-orbit control system.The main contents are:(1)Establish the satellite's attitude kinematics model and attitude dynamics model.Through the study of common coordinate systems describing the attitude of satellites in orbit,the mutual transformation relations between coordinate systems are analyzed;the common Euler angle description method and quaternion description method for describing satellite attitudes are compared according to their advantages and disadvantages.Intuitive analysis uses Euler angle description method to establish the satellite's attitude kinematics model.When a large number of calculations are needed,the quaternion descriptive method is used to establish the attitude kinematics model of the satellite,and establishes the satellite attitude dynamics model with the flywheel as the implementing agency.(2)Design the attitude determination system based on the "star sensor + gyro" combination.The attitude determination methods commonly used in satellite systems are studied.The attitude estimation method is used to estimate the on-orbit attitude of satellites based on highprecision control requirements.The performance of commonly used attitude sensors is compared.Selecting star sensors and gyroscopes as sensor combinations for attitude determination systems and establishing corresponding mathematical measurement models;using the extended Kalman filter algorithm to design the attitude estimator,and simulation to verify the accuracy of the estimation can meet the system requirements.(3)Design a flywheel-based actuator system.To study the common implementing agencies of satellite systems,according to the requirements of the system on the longevity and high precision of the actuators,choose the flywheel as the main research object;analyze the structure and internal disturbance of the flywheel,and establish the dynamic model of the flywheel and the internal friction interference model.According to the requirements of the control system and the performance indicators of the flywheel,the flywheel control system based on the speed feedback is designed and simulated.The result shows that the flywheel system can overcome the internal friction disturbance and reproduce the torque command of the satellite control system.(4)Designing a zero-momentum three-axis stable attitude control system for solar power plants.Based on the high precision requirements of the system,a mathematical model of a three-axis zero-momentum stability satellite attitude control system based on error quaternion and error angular velocity is developed;The PID control rate and the sliding mode variable structure control rate are respectively designed for the control system according to the attitude and dynamics equations of the satellite,and the control effects of the two control modes are simulated and compared.The results show that both control modes can make the system reach a stable state,but the control effects have their own advantages and disadvantages..