Smooth attitude feedback control with non-holonomic constraints

The paper considers the problem of asymptotically driving, via feedback control, the attitude of a reaction wheels actuated spacecraft, whenever operating in failure mode. In this case the presence of only two active reaction wheels constrain the spacecraft angular velocity vector to lie on one of the aircraft coordinate planes. The presented analysis, though performed at a kinematic level only, however parallels the ones originally presented in Byrnes and Isidori (1991) and Tsioratis et al. (1995). In these works, the possibility of asymptotically and smoothly driving the system toward any final desired attitude was in fact proven (under the assumption of a zero initial spin rate along the unactuated axis). The basic aim of this paper is that of showing that with a more simple, and in a sense more natural, choice for the attitude parametrization, a much more simple form for a smooth feedback control law can be obtained, possibly characterized by more efficient qualities concerning its stabilizing properties and gain parameters tuning characteristics.