Scheduled input shaping based attitude agile control for flexible spacecraft with vibration suppression

This study tackles the critical challenge of achieving high-precision and rapid attitude maneuvers for underactuated flexible spacecraft, where rigid-flexible coupling poses significant control difficulties. A novel dual-vibration suppression attitude control strategy is proposed, seamlessly integrating scheduled input shaping, attitude path planning, and state feedback control within the Fully Actuated System (FAS) framework. This approach effectively mitigates vibrations induced by the rigid-flexible coupling while ensuring agile and precise attitude maneuvers. To address the absence of direct modal variable measurements for flexible appendages and the presence of external disturbances, a desired linear system is formulated using the FAS approach, with nonlinearity compensation provided by a nonlinear extended disturbance observer. Specifically, a two-mode input shaper, operating independently of the feedback loop, is designed to shape reference attitudes generated via sinusoidal angular acceleration path planning, eliminating residual vibrations. The proposed method demonstrates robust performance, enabling rapid attitude transitions while suppressing elastic vibrations efficiently. Numerical simulations validate the effectiveness and robustness of the control strategy, highlighting its potential for practical applications in flexible spacecraft attitude control.