Robust identification of lightly damped flexible structures by means of orthonormal bases

We consider the problem of robust identification of lightly damped flexible structures by means of a family of orthonormal basis functions, in order to model the dynamics of this kind of systems in a certain frequency range of interest. It is possible in this way to reduce conservativeness of the identification process. We propose a method to generate the orthonormal bases that is based on the cascade of balanced state-space realizations of all-pass filters, and develop for this case a less conservative explicit worst case error bounds. We present an application of this method to both simulated and experimental frequency response data