Disturbance Observer-Based Active Vibration Suppression and Attitude Control for Flexible Spacecraft

In this article, active vibration suppression and attitude control for flexible spacecraft under model uncertainty and external disturbance are investigated. First, an adaptive disturbance observer (ADO) and flexible vibration observer (FVO) are proposed to estimate the lumped uncertainty and flexible vibration. It is shown that the proposed ADO is nonoverestimated and the first derivative upper bound of disturbance is unknown. Then, based on the proposed observers, a novel controller is designed to suppress flexible vibration and realize attitude control. The remarkable feature of the designed algorithm is that flexible vibration is suppressed and attitude tracking is guaranteed simultaneously without intelligent materials which are used to suppress flexible vibration in the previous work. In addition, high-precision attitude control can be achieved. The rigorous proof of closed-loop system stability is presented using Lyapunov techniques. Finally, numerical simulations are given to illustrate the efficiency of the proposed algorithm.