Nonlinear H _∞ decoupling control with parameter uncertainties of hovering flight vehicle

This paper proposes a new approach to consider nonlinear H _∞ control of hovering vehicles described by six degree-of-freedom nonlinear dynamics with plant uncertainties due to the variation of moments of inertia caused by fuel consumption and/or payload operation. Taking into account nonlinear effect, plant uncertainty, and exogenous disturbances caused by 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.