A novel approach for sun gear fault localization using on-rotor sensing and tidal periods effect

Due to the complex structure of planetary gearboxes, fault localization through vibration analysis presents certain challenges. Existing methods rely on absolute phase references provided by external laser tachometers, which are challenging to implement in complex industrial settings. To overcome these limitations, this study introduces a novel method for fault localization in planetary gearboxes utilizing a single On-Rotor Sensing (ORS) sensor. This method utilizes ORS technology to capture high signal-to-noise ratio vibration signals and employs position information derived from changes in gravitational acceleration sensed by the sensor as the absolute phase reference for locating faulty sun gear teeth. Subsequently, the phase relationships between the extracted and enhanced fault impulse signals from the vibration signals and the absolute phase reference were analyzed. By integrating the effects of tidal periods effect, encodings for the number of single-tooth meshings lagging behind the absolute phase reference at different positions of the faulty sun gear tooth are derived. Finally, two indicators, mean Spearman coefficient (MSC) and mean encoding value (MEV), are employed to locate the faulty sun gear tooth. The proposed method is validated on a planetary gearbox test rig with the sun gear fault exhibiting in different gear tooth, showing the proposed method can effectively identify the potential faulty sun gear tooth.