Dynamics And Control Of Integrated Of Attitude-orbit Co-location Diffraction Spacecraft

High orbit and high resolution earth observation is an efficient way of earth observation explored by space agencies of various countries.Due to orbit limitation,LEO earth observation spacecraft can not maintain continuous and long-term observation of a region.Although the geostationary orbit has the time resolution for the observation of a specific area,its resolution is difficult to guarantee due to the high orbit.Therefore,diffractive imaging technology is used to deploy diffractive film spacecraft and imaging spacecraft in geostationary orbit respectively to form a co-location spacecraft to meet the requirements of time and space resolution.In this paper,the dynamic modeling and control process of the co-location diffraction electromagnetic spacecraft are deeply studied,focusing on solving the problem of attitude orbit integrated dynamic modeling and control of the co-location diffraction electromagnetic spacecraft.The concrete work includes:Aiming at the problem of position and attitude integrated modeling of co-location diffraction spacecraft,based on dual quaternion,the rigid torsion coupling relative dynamic model of diffraction membrane spacecraft and the relative dynamic model of co-location two spacecraft are established.Considering the structural characteristics of the co-location diffraction imaging system,the diffractive thin film spacecraft is abstracted as a rigid flexible coupling structure,and the coupled rigid flexible dynamic equation is derived by using dual quaternion.Considering the advantages of electromagnetic force as the control force of co-location diffraction imaging system and the advantages of dual quaternion in describing relative pose motion,the form of electromagnetic force described by dual quaternion is derived,and the relative dynamics model of two co-location spacecraft based on dual quaternion is established.Aiming at the problem of higher accuracy of state measurement and control for co-location spacecraft,based on nonlinear relative orbit dynamics model,a nonlinear robust control system is proposed for co-location spacecraft in diffraction imaging process,which needs relative position and relative velocity information.It is proved that the closed-loop control system can achieve global asymptotic convergence.In view of the external interference and model uncertainty in the diffraction imaging process,a nonsingular sliding mode control algorithm based on free magnetic dipole and switching control strategy is designed by using the anti-interference performance of sliding mode control to external interference,insensitive to parameter changes and strong robustness,and the computational efficiency and singularity of the control algorithm are studied.Aiming at the problem of attitude orbit integrated control of co-location diffraction spacecraft,based on the dual quaternion coupled relative dynamics model,the sliding mode adaptive control method with adaptive identification is designed by combining the sliding mode variable structure control and adaptive control.The stability of the closed-loop control system is proved by Lyapunov theory.In order to further improve the robustness of the system,a robust adaptive controller without model information is designed and verified by simulation.