  The existing attitude controllers (without angular velocity measurements)
involve explicitly the orientation (\textit{e.g.,} the unit-quaternion) in the
feedback. Unfortunately, there does not exist any sensor that directly measures
the orientation of a rigid body, and hence, the attitude must be reconstructed
using a set of inertial vector measurements as well as the angular velocity
(which is assumed to be unavailable in velocity-free control schemes). To
overcome this \textit{circular reasoning}-like problem, we propose a
velocity-free attitude stabilization control scheme relying solely on inertial
vector measurements. The originality of this control strategy stems from the
fact that the reconstruction of the attitude as well as the angular velocity
measurements are not required at all. Moreover, as a byproduct of our design
approach, the proposed controller does not lead to the unwinding phenomenon
encountered in unit-quaternion based attitude controllers.
