A hybrid approach for fault diagnosis of planetary bearings using an internal vibration sensor

•We develop a hybrid approach for fault diagnosis of planetary bearings.•Accelerometer is mounted internally on the planet carrier for better detection.•Detection algorism is developed by using several advanced DSP techniques.•Optimized spectral kurtosis is used for demodulation band selection.•Both inner race and outer race faults of the planetary bearings can be detected.

Planetary gearboxes exhibit unique challenges in bearing fault detection. This paper presents a hybrid approach for fault diagnosis of planetary bearings using an internal vibration sensor and novel signal processing strategies. An accelerometer is mounted internally on the planet carrier to address the issues of variable transmission path. An effective bearing faults detection algorism is developed by employing several advanced signal processing techniques, including Cepstrum whitening, minimum entropy deconvolution (MED), spectral kurtosis (SK) and envelope analysis. The adverse effect of the electromagnetic interference in the signal due to the use of a slip ring is tackled by optimizing the SK technique for demodulation band selection. The proposed method is assessed by analyzing experimental data from a planetary gearbox test rig with seeded bearing faults. The result shows that the new method can effectively detect both inner race and outer race faults of the planetary bearing.