Research On Key Technologies Of Spacecraft Attitude And Orbit Control Ground Simulation System Based On Air Float Platform

With the rapid development of modern science and technology,space technology has become an important standard to measure a country’s hard strength as a top science and technology field in which countries have invested a lot of resources.At present,there are various missions in the space field,the complexity of which is constantly increasing,the difficulty is getting bigger and bigger,and the requirements for spacecraft are getting higher and higher.Spacecraft is a kind of space flight product with high risk,high investment and high benefit.In the process of development,it is usually necessary to carry out pre-ground simulation and experiments to ensure the rationality of scheme design and the accuracy of control parameter selection,thus reducing risks and saving costs.Based on a five-degree-offreedom simulator,this paper conducts ground simulation of spacecraft attitude measurement and control.Firstly,the current situation of related fields at home and abroad is analyzed.In the field of spacecraft ground simulation,research abroad is becoming more and more mature,and research efforts have been intensified in China.Several sets of equipment have been put into use.In the research of satellite attitude fusion algorithm,the existing algorithms are mainly divided into deterministic algorithm and state estimation algorithm.At present,the latter has higher accuracy and wider application range.In the aspect of spacecraft attitude maneuver,compared with traditional actuators(such as magnetic torquers,jet devices,flywheels,etc.),single-frame control torque gyroscopes(SGCMG)have the advantages of strong torque amplification,continuous and stable output torque,high accuracy,simple structure,rapid response,and so on,so they have been more and more widely used.Then,through studying the structure and composition of the five-degree-offreedom simulator,its mathematical model is established.Firstly,the structure and working mode of the automatic balancing system and the centroid inertia independent adjusting system of the simulator are analyzed.On this basis,the influence of the balancing mass on the simulator attitude when the centroid inertia adjusting system is running is studied,and thus the simulator attitude dynamics model and kinematics model considering the balancing mass are established.Then,the localization algorithm using Kalman filter to fuse the IMU and vision sensor data is studied.Firstly,the positioning algorithm of strapdown inertial navigation system and the general method of data processing using Kalman filter are analyzed.On this basis,the algorithm of data fusion between inertial navigation system and vision sensor using Kalman filter is studied and simulated to verify the effect of Kalman filter.The control method of single frame control moment gyro for fast attitude maneuver is studied.Firstly,the torque output principle of single-frame control torque gyroscopes is analyzed.Secondly,on this basis,the common control laws of gyro groups are studied,and the singular phenomena of gyro groups and the singular evading ability of each control law are analyzed through simulation.Finally,PID control,synovial membrane variable structure control and backstepping control are used to control the attitude of the five-degree-of-freedom simulator respectively,and the control effects of the three control laws are compared through simulation.Aiming at the singularity problem of gyro group,the global singularity avoidance control law with stronger singularity avoidance capability is studied.Since the reference trajectory tracking method is used for attitude maneuver,the design scheme of the reference trajectory is first studied.Then,taking pyramid configuration and pentapyramid configuration as research objects,the causes of singular problems of gyro groups are analyzed by simulating the angular momentum envelope of their singular states.Finally,a global singular evasive control law is designed on this basis,and its singular evasive ability and practical value are verified by simulation.