Disturbance observer based composite attitude stabilization of flexible spacecraft

In this paper, a disturbance-observer-based composite attitude controller is proposed for attitude control and stabilization of flexible spacecraft. This approach is composed of two parts. First, a disturbance observer is designed to estimate the disturbance from the flexible appendages. Solving Linear Matrix Inequality (LMI) helps to determine the design parameters of disturbance observer based control (DOBC). Subsequently, an integral sliding mode controller (ISMC) is used to address other kinds of disturbances, such as space environmental disturbance torques, unmolded uncertainties, and noises from actuators and sensors. Simulation results are provided to verify the effectiveness of the proposed control scheme.