Quaternion feedback regulator for large angle maneuvers of underactuated spacecraft

A quaternion feedback regulator is developed to yield three-axis rate stabilization of an underactuated rigid spacecraft's attitude with two body-fixed control torques and arbitrary inertia matrix. Stable control is achieved by properly combining a generalized inverse component for feedback linearization and an auxiliary input to stabilize the underactuated system. The proposed control yields local stability within a domain of attraction through perturbed feedback linearization. The generalized inverse is damped near a bound on an inherent singularity to provide piecewise-smooth control. Numerical simulation results for a detumbling to a desired orientation maneuver are presented for an asymmetric spacecraft with two bounded body-fixed control torques to demonstrate the capability of the proposed attitude control method. Although this control method is not intended to provide attitude maintenance for attitude tracking or in the presence of relatively large disturbance torques, it may prove widely applicable for detumbling and reorientation maneuvers of spacecraft with only two available control torques.