Rotary gust rejection for helicopters

For the case of helicopters in straight horizontal flight, the effects of a rotary gust to the forward velocity and the downward velocity of the helicopter are rejected. The rotor commands appear to be independent, i.e. to be enough to control the dynamics of the horizontal and vertical motion. In this case, the rotary gust rejection problem is proved to be always solvable, via a state feedback law. The general analytic expression of the feedback controller, satisfying the disturbance rejection design requirement, is derived. The necessary and sufficient conditions for disturbance rejection and simultaneous stability are established. Simulation results are derived for an SA-330 PUMA helicopter