A new method for blind identification of structures with limited sensors

Abstract

In this paper, a new identification method based on second-order blind source separation (SOBSS) has been proposed. A major restriction of the standard SOBSS algorithm in the identification context is that the responses in all degree of freedoms (DOFs) should be recorded. Several studies have already been carried out to overcome this issue by synthetically increasing the number of responses. Using a different strategy, in this paper, the problem has been resolved by reducing the number of active modes in the measurements using the filtering technique. The measurements are filtered according to their Fourier spectra such that the number of active modes in the filtered responses is equal to the number of sensors. Then, the SOBSS algorithm is applied to the filtered responses to obtain the modal coordinates and mode shape vectors. Two numerical simulations and a finite element model of a benchmark structure have been used to evaluate the accuracy of the proposed method. The results show that the proposed method can accurately extract the modal parameters of the structures using limited sensors, in both the cases of free or ambient vibrations. However, in the case of poorly excited modes, greater accuracy can be achieved by increasing the number of measured DOFs. Owing to the filtering step, the proposed method showed a much better performance in the case of noisy measurements, in comparison with the standard SOBSS algorithm.