Vibration Separation and Diagnostics of Planetary Geartrains

This paper extends a synchronous averaging technique to incorporate the use of multiple sensors to extract the vibration signals associated with the sun and planet gears of planetary geartrains. The use of multiple sensors mounted along the annulus gear of a planetary gearbox is shown to overcome four limitations of the existing single sensor methodology. First, the constraints on the gearbox geometry in determining whether the technique can be applied are reduced. Second the speed of computation of the technique is increased. Third, the robustness of the methodology to possible sensors failures is enhanced. Finally, susceptibility to noise that is synchronized with the rotation of the carrier is reduced. The methodology is applied to data collected from a miniature planetary transmission system with and without seeded faults. Results indicate that the multiple sensor methodology is able to separate the vibration signals associated with the sun and planet gears in the presence of sensor noise and synchronized disturbances. In addition, the separated vibrations signals are analyzed using the continuous wavelet transform to illustrate that planet and sun gear faults can be easily detected after separation.