Fault Feature Extraction of Helicopter Rotor System Based on HHT Envelope Demodulation

Abstract

Helicopter rotor system (HRS), which is a key component without redundancy design, is of significant importance for flight safety. Working under demanding environment, HRS faults are hard to detect. This paper proposes a new approach based on Hilbert-Huang Transform (HHT) and envelope demodulation to realize HRS fault feature extraction under strong interference. Empirical mode decomposition (EMD) was used to decompose the vibration signal into several intrinsic mode functions (IMFs) first, then, Hilbert transformation was applied to the IMFs to get the envelopes. And at last, fast Fourier transform (FFT) was adopted with the IMF which was closely related to the fault features. This method can avoid the selection of center frequency and filter band in resonance demodulation method, therefore, it has good adaptivity. Two commonly occurring faults in HRS are simulated on a test rig to validate the performance and effectiveness of the proposed method. The experimental results demonstrate that the proposed method based on HHT envelope demodulation is effective for the HRS fault feature extraction.