Multivariable stability-margin optimisation with decoupling and output regulation

A procedure is developed for maximising frequency-weighted stability-margin singular values for a multivariable linear time-invariant feedback control system subject to design constraints requiring decoupling and asymptotic tracking in the presence of unstable command and disturbance signals and closed-loop stability. The results are derived using Sarason´s H¿¿ optimal interpolation results, together with a new multivariable realisability lemma.