A new Wasserstein distance- and cumulative sum-dependent health indicator and its application in prediction of remaining useful life of bearing

The safety and reliability of mechanical performance are affected by the condition (health status) of the bearings. A health indicator (HI) with high monotonicity and robustness is a helpful tool to simplify the predictive model and improve prediction accuracy. In this paper, a new health indicator based on the Wasserstein distance (WD) and cumulative sum (CUSUM) is proposed. First, a standard normal signal is simulated as the reference. The second step is to calculate the frequency distribution histogram of the reference signal and that of monitoring signals for the bearing. The next step is to obtain the WD between the frequency distribution histogram of the reference signal and that of the monitoring signal. Finally, the fluctuation of the WD is amplified by applying the CUSUM. The performance of the proposed HI is evaluated by testing three run-to-failure datasets. The results show that the proposed HI has better monotonicity and robustness and can be effectively used to predict the remaining useful life of bearings.