Fault Diagnosis of Planetary Gearbox under Nonstationary Conditions Based on the Velocity Synchronous Chirplet Transform

Planetary gearboxes are widely used in industrial equipment and they usually work under non-stationary conditions. Condition monitoring and fault diagnosis are important for them to avoid run-time breakdowns and one effective way is analyzing the vibration signal collected from them in time-frequency plane. This paper presents a time-frequency analysis method, named the velocity synchronous chirplet transform (VSCT), to reveal the time-varying characteristics of planetary gearbox vibration signal for fault diagnosis. Compared with other popular time-frequency methods, the advantages of VSCT include: (1) it is free from smear effect and cross-term interference and (2) it is able to determine the parameters adaptively according to the signal, therefore avoid error-prone human intervention. In this paper, the VSCT method is applied to detect the time-varying fault characteristic frequencies of sun gear from a lab planetary gearbox experimental signal.