Constrained Attitude Stabilization and Synchronization of Multi-Combined Spacecraft via Disturbance Observer

This work investigates the attitude stabilization and synchronization problem for multi-combined spacecraft with time-varying inertia parameters, external disturbances, and input constraints. First, the comprehensive disturbance is reconstructed considering the influence of inertia uncertainties for controller system design. And then, a novel disturbance observer is developed, and a state feedback controller developed through comprehensive disturbance estimation is proposed. The characteristic of uniform ultimate boundedness for the closed-loop attitude system is proved according to Lyapunov stability analysis, producing the sufficient linear matrix inequality (LMI) condition for the disturbance observer and state feedback controller designs. It is worth noting that the observer and controller gain matrices are solved simultaneously. The feasibility of the attitude stabilization control strategy is demonstrated through numerical simulations.