Wavelet analysis approach to identification of systems with dead time application to boiler process

The wavelet analysis is superior to the Fourier analysis in the detectability of temporal (or spatial) information of signals. Therefore, the use of this time-frequency analysis approach makes it possible to estimate such singular points as dead time, and the use of the analyzing wavelet which exists locally in the frequency domain makes it possible to estimate the frequency response of the transfer function. First, we present a dead time identification technique by using the wavelet transform of the cross-spectra of input/output (I/O) data. Secondly, we present a method for obtaining the frequency response of the system to be considered by directly using the wavelet transform of the auto-/cross-correlation functions of the I/O data. Thirdly, we determine the parameters in the transfer function by using the curve fitting in the least squares sense. Finally, we demonstrate the feasibility and validity of our identification procedure through experiments for an actual boiler process