Feature Extraction of Helicopter Fault Signal Based on HHT

Since most of helicopter fault signals are non-linear and non-stationary, the method based on Fourier transform (FT) and wavelet analysis are not applicable any longer. The feature extraction method based on Hilbert-Huang transform (HHT), a new method for processing non-stationary and non-linear signals, is applied to analyze helicopter fault signals. The signal is firstly decomposed into intrinsic mode function (IMF) by the empirical mode decomposition (EMD) method. Then Hilbert spectrum and Hilbert marginal spectrum are obtained from instantaneous frequency and amplitude obtained from Hilbert transform (HT). The simulation results are analyzed and compared with FT method, and then suggest the effectiveness of this method based on HHT.