Research on Attitude and Orbit Coupled Control Method for VLEO Satellites Based on Aerodynamics

Very Low Earth Orbit (VLEO) satellites face severe aerodynamic coupling disturbances, and traditional singlepropulsionsystems struggle to meet the strict fuel constraints of long-term formation missions. To address this challenge, thispaper proposes a low-propellant attitude-orbit coupled control scheme for a slender-body satellite utilizing a combination offour-quadrant independently rotating aerodynamic panels and an electric propulsion (EP) system. First, a high-precision, stronglycoupled dynamics model is established based on the free molecular flow theory. To overcome the physical limitation thataerodynamic drag cannot provide out-of-plane control, a hybrid aerodynamic/EP actuation architecture is designed. In theattitude control layer, a composite disturbance observer and a null-space projection control allocation strategy are designed toachieve decoupled regulation of tangential differential drag while ensuring three-axis attitude stability. In the relative trajectorycontrol layer, the Gauss Pseudospectral Method (GPM) is employed to generate an optimal reference trajectory consideringthrust and aerodynamic saturation constraints. Furthermore, a Fast Nonsingular Terminal Sliding Mode Controller (FNTSMC)is designed to achieve synergistic and high-precision tracking of in-plane aerodynamic forces and out-of-plane EP thrusts,effectively rejecting atmospheric density perturbations. Finally, an "attitude-first"time-scale separation architecture is proposedto resolve the allocation dilemma of the heterogeneous coupled system. Simulation results demonstrate that the proposed methodsignificantly achieves high-precision attitude stability and formation control, providing a highly efficient solution for long-termVLEO missions.