Relative attitude-orbit gain-adapting enhanced coupling control for underactuated spacecraft

This article addresses the complex underactuated control problem involving systems with fewer control inputs than degrees of freedom, where multiple states are governed by a single actuator. A hierarchical gain-adapting enhanced coupling control method is proposed, which is applied to the relative attitude-orbit coupling underactuated control of thrust-vectoring spacecraft during high-thrust proximity maneuvers. First, the underactuated characteristics of the system, which features two inputs and six outputs, are analyzed using the relative attitude-orbit coupling model. Subsequently, a gain-adapting enhanced coupling control method is proposed to handle the complex underactuation, while an adaptive fuzzy observer is employed to estimate multi-source disturbances and uncertainties. Simulation results demonstrate the effectiveness of the proposed controller in achieving relative attitude-orbit coupling control, thereby providing a reliable theoretical foundation for rapid proximity operations of underactuated spacecraft.