Fixed-Time Disturbance Observer-Based Attitude Prescribed Performance Predictive Control for Flexible Spacecraft

This article investigates the problem of improving control performance during flexible spacecraft maneuvers, hampered by system uncertainties, environmental disturbances, and flexible vibrations. A fixed-time disturbance observer-based prescribed performance predictive control method is proposed. First, a nonlinear second-order fully actuated discrete system model is introduced to characterize the dynamic behavior and nonlinearities of the spacecraft attitude control system. The fixed-time disturbance observer is employed to estimate and compensate for the lumped disturbances. Subsequently, an incremental second-order fully actuated predictive model is established using a Diophantine equation to replace reduced-order equations. Further, an optimal controller is obtained through multistep ahead prediction, which considers constraints on attitude tracking performance and prescribed performance. Additionally, a necessary and sufficient condition is provided to analyze the tracking performance and stability of the closed-loop system. Finally, numerical simulations of flexible spacecraft maneuvering and attitude tracking validate the effectiveness.