Why EMD and similar decompositions are of little benefit for bearing diagnostics

作者：Robert B. Randall, Jérôme Antoni · 发表于：Mechanical Systems and Signal Processing · 年份：2023 · DOI：10.1016/j.ymssp.2023.110207 · 被引用次数：117 · 研究领域：Machine Fault Diagnosis Techniques、Gear and Bearing Dynamics Analysis、Mechanical Failure Analysis and Simulation

Empirical mode decomposition (EMD) is a way of decomposing complex signals into a sum of “mono-components”, i.e. intrinsic mode functions (IMFs), each of which can be considered as a single carrier frequency, modulated in both amplitude and phase/frequency (an analytic signal), so that both amplitude and phase remain continuous and differentiable, the latter to instantaneous frequency. In many cases, the instantaneous frequency and amplitude could be valuable diagnostic features, for example with gear vibrations. Many authors have suggested applying this technique to the diagnostics of rolling element bearings (REBs), but this paper shows that REB signals intrinsically do not have such properties, except perhaps in short bursts, so that the excessive computation time trying to ensure continuous phase is wasted. Much more appropriate methods exist to extract the optimum envelope signal, which contains the desired diagnostic information, based on more relevant criteria. As its name suggests, the EMD process is empirical, with no analytical solution, so that different results can be obtained from different segments of the same signal, partly because of different noise content. Another way of obtaining IMFs is by using variational mode decomposition (VMD), which does have an analytical solution, making it less sensitive to noise, but still assumes that the signal can be validly decomposed into mono-components, which is not the case for bearing signals. The EMD process has two add...