On the extension of robust global adaptive control results to unstructured time-varying systems

This note extends the robust global direct adaptive control results of Kosut and Friedlander [1] and Kosut [2] to the case of linear finite-dimensional systems with unstructured time-varying uncertainties. Subject to conditions which include i) a certain operator (usually denotedH^{*}_{e0}) is strictly positive real and ii) the tuned error lies in L2, theorems are presented establishing the L2andL_{infty}stability of the adaptive control scheme.