First Results on Regularized Time-Varying Operational Modal Analysis

This paper presents an efficient nonparametric time-varying time domain system identification method for the Operational Modal Analysis (OMA) framework. OMA tackles industrial measurements of vibrating structures in real-life operating conditions without the exact knowledge of the excitation signal. In case of time-varying Operational Modal Analysis it is desired to carefully verify and track the vibration behavior, since during flutter appearance, system destruction can occur. In this work a method is provided to estimate the time-varying output autocorrelation function of vibrating structures and applied to a measurement of wind tunnel testing of an airplane. The proposed method is a novel extension of the regularization methods that have been developed for impulse response estimates of linear time-invariant systems. Using the proposed methodology, the estimated time-varying two-dimensional output autocorrelation model provides a good data-fit with respect to tracking of varying resonances.