  An approach to the control of a VTOL vehicle equipped with complementary
thrust-direction tilting capabilities that nominally yield full actuation of
the vehicle's position and attitude is developed. The particularity and
difficulty of the control problem are epitomized by the existence of a maximal
thrust-tilting angle which forbids complete and decoupled control of the
vehicle's position and attitude in all situations. This problem is here
addressed via the formalism of primary and secondary objectives and by
extending a solution previously derived in the fixed thrust-direction case. The
proposed control design is also illustrated by simulation results involving a
quadrotor UAV with all propellers axes pointing in the same monitored tilted
direction.
