Abstract

BALDEN, V.H.  and  NURICK, G.N.. Experiences with the Eigensystem Realization Algorithm. R&D j. (Matieland, Online) [online]. 1998, vol.14, pp.23-29. ISSN 2309-8988.

The Eigensystem Realization Algorithm (ERA) is a multi input / multi output time domain implementation of system realization theory. The input to the ERA is impulse response functions, typically from vibration analysis of a structure. The output of the ERA is realized state-space matrices that reconstruct the impulse response functions and contain the excited structure's modal characteristics. This article presents a brief mathematical background of the ERA and discusses the application to experimental vibration data. Practical issues of the Hankel matrix block dimensions and the number of singular values to retain are discussed. It is shown that the modal parameters converge only after massive over-specification of the Hankel matrix block dimensions and that the number of retained singular values do not determine the model order. Rather, the ERA user determines the model order by selecting successfully transformed and reliable modes that accurately reconstruct both the measured impulse and frequency response functions.

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