Gyro-free attitude reorientation control of spacecraft with state and input constraints

This paper introduces an explicit reference governor-based control scheme to address the gyro-free spacecraft attitude reorientation problem, considering specific constraints such as pointing, angular velocity, and input saturation. The proposed control scheme operates in two layers, ensuring the asymptotic stability of the attitude while adhering to the aforementioned constraints. The inner layer employs output feedback control utilizing an angular velocity observer based on immersion and invariance technology. Through an analysis of the geometry associated with the pointing constraint, determination of the upper bound of angular velocity, and optimization of the control input solution, the reference layer establishes a safety boundary described by the invariant set. 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 substantiate the efficacy of the proposed constrained attitude control algorithm through numerical simulations.