System-Level Prognostics Under Mission Profile Effects Using Inoperability Input–Output Model

During the two last decades, the failure prognostics has been given an increasing importance by the researchers and industrials thanks to the benefits its results can induce in terms of availability, security, and maintenance costs. However, a detailed study of the literature in the domain shows that most of the published works deal with prognostics at component level, where the failure of the system is linked to the failure of its critical components. Even if this assumption can be tolerated in some cases, it cannot be generalized. This is because, in practice, the components are interconnected and, consequently, a degradation of one component can affect the others leading to a modification in the system's health state and then in its remaining useful life (RUL). To take into account this reality, a new model for prognostics is proposed in this article, namely inoperability input-output model (IIM). This model allows representing multicomponent systems while considering the interactions between their components. More than that, the IIM enables to integrate the mission profile effects on the system degradations to make its RUL predictions more accurate. To illustrate the effectiveness of the proposed modeling approach, a mechatronic system is considered as a case study.