Estimation of the instantaneous rotational frequency of gear transmission with large speed variations using short-time angular resampling and ridge-enhancing techniques

Instantaneous rotational frequency (IRF) is essential for most of the gear fault diagnosis methods used for nonstationary conditions. However, estimating the IRF under large speed-variation conditions is challenging. In this work, we developed a short time angular resampling and ridge-enhancing (STAR-RE) method for estimating the IRF of a gear transmission system of large speed variations. The method is integrated with a rigorous approach for eliminating ridge smearing based on angular resampling and a straightforward scheme for enhancing the target ridge by merging the ridges of several gear meshing harmonics. Data collected from a laboratory gearbox and an in-field wind turbine gearbox operated at variable speed regimes were used to test the accuracy and effectiveness of the STAR-RE method. The results indicated that the STAR-RE method achieved more accurate IRFs than the benchmark methods.