A novel disturbance observer for attitude control of flexible spacecraft

This paper introduce the high accuracy attitude control method of spacecraft with flexible appendages. It is known that the unwanted vibration modes of flexible appendages will degrade the performance of the flexible spacecraft attitude control system. In this paper, the vibration modes are considered as an `equivalent' disturbance, and a novel nonlinear disturbance observer is designed to estimate this `equivalent' disturbance. A disturbance feed-forward compensate controller (DFCC) is designed based on the nonlinear disturbance observer and the feedback linearization control to improve the performance of attitude control system. The flexible spacecraft is controlled by the actuator locate on the central rigid body. Simulation results investigate that the DFCC designed in this paper improved the performance of the attitude control system.