A μ analysis technique without frequency gridding

The aim of this paper is to directly compute an upper bound of the maximal structured singular value over a frequency interval. In the context of the mixed μ upper bound of Fan et al. (1991) and Young et al. (1995), an heuristic method has been proposed, namely to synthesize D,G scaling matrices, which simultaneously work at two neighbouring frequencies ω₁ and ω₂. Interestingly, even if ω₁ and ω₂ are not a priori very close, it remains possible to synthesize D,G scaling matrices, which simultaneously work at those two frequencies and to check a posteriori that D and G work indeed on the whole segment [ω₁ ω₂]. An important contribution of this paper is to provide an easy and yet rigorous method, for solving this last problem. The technique is finally successfully applied to a non-academic example, which may be significant to a large flexible system