Gearbox coupling modulation separation method based on match pursuit and correlation filtering

• A new method for separating coupling modulation from vibration signal of gearbox based on match pursuit and correlation filtering is proposed.
• Two sub-dictionaries which are used for extracting distributed fault and impact fault are specially designed.
• An amplitude recovery step is conducted to improve matching accuracy in the match pursuit.
• The method is confirmed through simulation and experimental results.

The vibration signal of faulty gearbox commonly involves complex coupling modulation components. The method of sparse representation has been successfully used for gearbox fault diagnosis, but most of the literatures only focus on the extraction of impact modulation and always neglect the steady modulation representing the distributed faults. This paper presents a new method for separating coupling modulation from vibration signal of gearbox based on match pursuit and correlation filtering. To separate the steady modulation caused by distributed fault and the impact modulation caused by impact fault, two sub-dictionaries are specially designed according to the gearbox operating and structural parameters and the characteristics of vibration signal. The new dictionaries have clear physical meaning and good adaptability. In addition, an amplitude recovery step is conducted to improve the matching accuracy in the match pursuit. Simulation and experimental results show that the proposed method can separate the coupling components of gearbox vibration signal effectively under intensive background noise.