Some frequency-domain approaches to the model reduction of delay systems

Abstract

We review a selection of techniques which have been found effective in the H2 and H∞ model reduction of delay systems, modeled using transfer functions. These include Fourier–Laguerre series, Padé approximants, shift-based approximations, Malmquist bases, partial fractions, wavelet-based techniques, Hankel-norm approximants and truncated state-space realizations. Some discussion of achievable error bounds is included.