SM identification of approximating models for H-infinity robust control

Set Membership (SM) H-infinity identification of mixed parametric and non-p arametric models is investigated, aimed to estimate a low-order approximati ng model and an identification error, giving a measure of the unmodelled dy namics in a form well suited for H-infinity control methodologies. In parti cular, the problem of estimating the parameters of the parametric part and the H-infinity bound on the modelling error is solved using frequency domai n data, supposing l(infinity) bounded measurement errors and that the syste m to be identified is exponentially stable. The effectiveness of the propos ed procedure is tested on some numerical examples, showing the advantages o f the proposed methods over the existing non-parametric H-infinity identifi cation approaches, in terms of lower model order and of tightness in the mo delling error bounds. Copyright (C) 1999 John Wiley & Sons, Ltd.