Robust identification with mixed time/frequency-domain experiments: theory and an application

We (1996) have recently proposed a new robust identification framework, based on the generalised interpolation theory, that allows for combining both frequency and time-domain experimental data. In this paper we apply this framework to the problem of identifying a two-degree of freedom structure used as a testbed for demonstrating damage-mitigation and life extension control concepts. This structure is poorly damped, leading to time and frequency domain responses that exhibit large peaks, thus rendering the identification problem nontrivial. The main advantage of the method, avoiding situations where good fitting in one domain is obtained at the expense of poor fitting in the other, is illustrated by comparing the results against those obtained using more classical pure L¹ and H_∞ methods