On robust stabilization synthesis for plants with block structured modeling uncertainty

In this paper we consider the problem of robust stabilization of plants with additive block-structured uncertainty. This problem reduces to an optimization problem of the form ¿-1,¿,Q in H¿ ||¿(A + BQC) ¿-1||¿, where ¿ is constrained to be block-diagonal. Existing methods addressing this problem require complete knowledge of the scaling functions ¿. In this paper we provide an alternative algorithm which requires only the values of ¿ at the unstable poles of the nominal plant. Determining the corresponding robust controller involves outer function interpolation and we provide here a new procedure for this problem. This procedure yields far lower order interpolants than previous methods. Also, we derive sufficient conditions for infinite stability margins for these problems.

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