Estimating Remaining Useful Life for Degrading Systems with Large Fluctuations

Abstract

Remaining useful life (RUL) prediction method based on degradation trajectory has been one of the most important parts in prognostics and health management (PHM). In the conventional model, the degradation data are usually used for degradation modeling directly. In engineering practice, the degradation of many systems presents a volatile situation, that is, fluctuation. In fact, the volatility of degradation data shows the stability of system, so it could be used to reflect the performance of system. As such, this paper proposes a new degradation model for RUL estimation based on the volatility of degradation data. Firstly the degradation data are decomposed into trend items and random items, which are defined as a stochastic process. Then the standard deviation of the stochastic process is defined as another performance variable because standard deviation reflects the system performance. Finally the Wiener process and the normal stochastic process are used to model the trend items and random items separately, and then the probability density function (PDF) of the RUL is obtained via a redefined failure threshold function that combines the trend items and the standard deviation of the random items. Two practical case studies demonstrate that, compared with traditional approaches, the proposed model can deal with the degradation data with many fluctuations better and can get a more reasonable result which is convenient for maintenance decision.

Hybrid Degradation Equipment Remaining Useful Life Prediction Oriented Parallel Simulation considering Model Soft Switch

“…Furthermore, similar to the previous study [ 23 ], Zhang et al [ 24 ] utilized a specific nonlinear Wiener process with the power low model to describe the continuous degradation and the same method to describe the randomly arriving shock. On the basis of the above modeling mechanism, Du et al [ 25 ] proposed a more generalized hybrid degradation model consisting of trend term and stochastic fluctuating term. It is worth noting that all the above latest research studies use one model to model the hybrid degradation process.…”