A Möbius Transform Approach for Improved MIMO Frequency Domain Identification
Paper i proceeding, 2021

To improve the numerical conditioning of a frequency domain subspace algorithm (FSID) when identifying continuous time transfer functions a general Mobius transformation can be employed. The Mobius transformation is a more general class of transformations which include the bilinear transformation as a special case. For the state-space model class of MIMO transfer functions we derive the relations describing how the state-space realization of a transfer function is converted under a Mobius transformation. With an extensive numerical example we illustrate that a particular choice of the Mobius transformation leads to transfer function estimates with, in general, significantly improved accuracy. Copyright (C) 2021 The Authors.

Frequency domain identification

System identification

Mobius transformation

Subspace methods

Continuous time system estimation


Tomas McKelvey

Chalmers, Elektroteknik, Signalbehandling och medicinsk teknik

Andrei Osipov

Chalmers, Elektroteknik, Signalbehandling och medicinsk teknik

Thomas Rylander

Chalmers, Elektroteknik, Signalbehandling och medicinsk teknik


2405-8963 (ISSN) 24058963 (eISSN)

Vol. 54 7 791-796

19th IFAC Symposium on System Identification (SYSID)
Padova, Italy,



Sannolikhetsteori och statistik

Matematisk analys



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