An Observer-Based Anti-unwinding Attitude Control Method for Flexible Spacecraft

In this paper, the anti-unwinding attitude controller design for flexible spacecraft in the presence of flexible vibration, inertia uncertainty, and environmental disturbance torques is considered and a novel flexible modal observer-based anti-unwinding attitude control method is proposed. First, two adaptive laws are designed to deal with inertia uncertainty and environmental disturbance torques. Then, a flexible modal observer and an observer-based controller are designed. It is proven that the closed-loop system under the proposed controller is asymptotically stable. The simulation results validate that the proposed control method achieves a good tracking performance and is feasible subject to flexible vibration, inertia uncertainty, and environmental disturbance torques.