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 denoted
H^{*}_{e0}
) is strictly positive real and ii) the tuned error lies in L
2
, theorems are presented establishing the L
2
and
L_{\infty}
stability of the adaptive control scheme.