Eigenstructure vs constrained H-infinity design for hypersonic winged cone

A variant of the eigenstructure assignment is developed to decouple phugoid and short periodic oscillations in longitudinal control of the winged cone , a benchmark hypersonic vehicle with airbreathing propulsion. The new meth od consists in minimizing the H-infinity norm of some closed-loop transfer matrix incorporating the undesirable couplings subject to the constraint th at the closed-loop poles are consistent with such specifications as the mil itary standard flying qualities of piloted aircraft. This constrained H-inf inity method,with proper frequency-dependent weights, provides, in an indir ect manner, the eigenstructure assignment consistent with the specification s on the responses. This new method and the traditional eigenstructure assi gnment are compared.