Eigenstructure vs constrained H super( 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 method consists in minimizing the H super( infinity ) norm of some closed-loop transfer matrix incorporating the undesirable couplings subject to the constraint that the closed-loop poles are consistent with such specifications as the military standard flying qualities of piloted aircraft. This constrained H super( infinity ) method, with proper frequency-dependent weights, provides, in an indirect manner, the eigenstructure assignment consistent with the specifications on the responses. This new method and the traditional eigenstructure assignment are compared.