Rolling bearings are widely used as important components of rotating machineries. However, faults are inevitable, which may lead to damages for equipment or even cause serious catastrophic consequences [1], [2]. Therefore, fault diagnosis and condition monitoring of the bearings are of great significance. Early diagnosis of bearing fault is helpful for minimizing the losses caused by failures. So far, this issue attracts many scholars to do in-depth and systematic exploration [3], [4], [5].
