New control laws for angular velocity and line-of-sight stabilization of under-actuated rigid spacecraft

This paper proposes a novel general Lyapunov-based line-of-sight (LOS) controller design for rigid spacecraft by means of two torques. Then, the approach is developed in order to simultaneously stabilize the angular velocity and LOS, while the LOS axis is unactuated. As a feature of the introduced controller, it is shown that the total closed loop system´s stability is robust against any unpredefined intrinsic saturability of actuators.