Anti-Disturbance Backstepping Attitude Control for Rigid-Flexible Coupling Spacecraft

This paper investigates the problem of attitude stabilization for rigid-flexible coupling spacecraft under external disturbances, parametric uncertainties, and measurement errors. First, the dynamical model for a rigid spacecraft with two symmetric solar arrays is derived based on the Lagrange method, and the measured kinematic and dynamic models are formulated, respectively, in terms of the measured values and errors. A robust anti-disturbance control law is hierarchically proposed to stabilize the attitude states via the backstepping method. For the first step, the lumped disturbance in the measured kinematic model is reconstructed from a finite-time integral sliding mode disturbance observer (FTISMDO), and a virtual control strategy is designed. For the second step, the overall uncertainties in the measured dynamic model are approximated by FTISMDO, and the actual control scheme is proposed based on the virtual control and disturbance observers. It is proved that the designed controller can guarantee that all attitude variables converge to small neighborhoods of origin asymptotically in the presence of interior and exterior disturbances. Finally, a numerical example is provided to demonstrate the disturbance rejection and robustness performance of the proposed control technique.