The application of the cyclic coherence for distributed planet fault detection in planetary gears

摘要

The vibration-based condition monitoring of planetary gears is a highly active and challenging field of research. Many signal processing techniques have been proposed, with the aim of promoting the fault component in the signal and, consequently, highlighting the fault signature (iethe damage symptom). Most of these techniques consider the fault contribution as being deterministic, which is true in the case of an advanced and localised fault. Such techniques may fail in other scenarios in which, for instance, the fault is of a distributed nature and its vibrational componentis weak. In such a case, the fault component is likely to be randomised and turns cyclostationary. The present paper suggests the presence of an additional cyclostationary component in planetary gear vibrations. The presence of this component is explained by the presence of load fluctuationsat the meshing points and the random micro-irregularity in the stiffness of gear components, as well as the presence of distributed faults. A simplified signal model is proposed to explain the vibration signal structure of healthy and faulty planetary gears (with a planet fault in the caseof the faulty gear). Also, a cyclostationary-based condition monitoring approach is proposed, based on the cyclic coherence. The proposed approach is validated on real-world vibration signals acquired from a planetary gear benchmark.