Constrained output feedback control of spacecraft attitude via explicit reference governor

This paper proposes an explicit reference governor-based control scheme for the velocity-free spacecraft attitude maneuver problem subject to the pointing constraint, the angular velocity constraint, and the input constraint. The proposed two-layer control scheme guarantees asymptotic stability of the attitude while satisfying the aforementioned constraints. The inner layer relies on output feedback control via an immersion and invariance technology-based angular velocity observer, enabling attitude stabilization without measuring angular velocity. By analyzing the geometry of the pointing constraint, the upper bound of the angular velocity, and the optimization solution of the control input, the safety boundary described by the invariant set is obtained in the reference layer. Additionally, we introduce the dynamic factor related to the angular velocity estimation error into the invariant set to prevent states from exceeding the constraint set due to unmeasurable angular velocity information. The shortest guidance path is then designed in the reference layer. Finally, we verify the effectiveness of the proposed constrained attitude control algorithm through numerical simulations.