Quantitative cross-feed and feedback design of helicopter in near hover flight

This paper examines the use of quantitative cross-feed design followed by diagonal feedback design to decouple, stabilize, and improve handling qualities of the UH-60 Black Hawk helicopter near hover. The Eight configurations used were classified according to the likelihood of their occurrence in practice, and this allows the performance for usual cases to be improved by a tradeoff with reduced but still quantitative performance for less usual operating conditions, The design is based on a set of linear models obtained from a nonlinear model with six-degree-of-freedom rigid fuselage with rigid rotor blades, each with a flap and lag degree of freedom. The Perron root of the interaction matrix is used as a measure of the level of interaction of uncertain multivariable plants, and the cross-feed design seeks to reduce the interaction index before quantitative design of a diagonal controller matrix is attempted. If the interaction index can be made to be less than unity by the design, stability of the diagonal-loop design guarantees stability of the closed-loop multivariable system. Performance is evaluated against some of the requirements of the Aeronautical Design standard, ADS-33D-PRF for near hover Right.