SM identification of approximating models for H∞ robust control

Set Membership (SM) H-infinity identification of mixed parametric and non-parametric models is investigated, aimed to estimate a low-order approximating model and an identification error, giving a measure of the unmodelled dynamics in a form well suited for H-infinity control methodologies. In particular, the problem of estimating the parameters of the parametric part and the H-infinity bound on the modelling error is solved using frequency domain data, supposing l(infinity) bounded measurement errors and that the system to be identified is exponentially stable. The effectiveness of the proposed procedure is tested on some numerical examples, showing the advantages of the proposed methods over the existing non-parametric H-infinity identification approaches, in terms of lower model order and of tightness in the modelling error bounds. Copyright (C) 1999 John Wiley & Sons, Ltd.