This paper proposes a new approach to nonlinear H∞ control of hovering vehicles described by six-degree-of-freedom nonlinear dynamics
with plant uncertainties due to variation of moments of inertia caused by
fuel consumption and/or payload operation. Taking into account nonlinear
effect, plant uncertainty, and wind gust, we show in this paper that the
six-degree-of-freedom nonlinear H ∞ controller can be exactly decoupled
into two three-degree-of-freedom controllers, one for translational motion
and the other for rotational motion, even though longitudinal and lateral
dynamics of flight vehicle in hover are highly nonlinear and severely
coupled. At the same time, the paper shows that the nonlinear H
∞decoupling controls in hover are robust to plant uncertainty and wind gust.