A procedure of vibration analysis from planetary gearbox under non-stationary cyclic operations by instantaneous frequency estimation in time-frequency domain

International audience; Condition monitoring of gearboxes via vibration analysis is well-recognized approach in scientific literature and also in engineering practice. However, in many cases machine works under non-stationary operating conditions (load and speed variation), that often requires special signal processing and pattern recognition suitable for time varying systems. One of key problem is to identify variation of external load or speed. Measurement of current consumed by electric motor or instantaneous speed obtained by processing of tachometer signal, in many practical situations (industrial condition) may be difficult or impossible. In such case non-stationary load variation may be identified by extraction of information hidden in vibration signal. For example it may be extracted from amplitude or frequency demodulation. Unfortunately both approaches are difficult (or even impossible) for our machines due to complexity of design and wide range of load/speed variation. In order to avoid these constrains in this paper new approach will be proposed and exploited for complex, multistage gearboxes with planetary stage. To extract information related to cyclic load variation, an instantaneous speed obtained via time-frequency spectrogram will be used. Algorithms for Instantaneous Frequency (IF) estimation via T-F maps have been initially developed by Millioz and Martin. In this paper a novel procedure for Instantaneous Speed estimation (based on IF identification by mentioned automatic algorithm) will be proposed, next the procedure will be applied to vibration signals from planetary gearboxes.