Supervision and Safety of Complex Systems

Chapter 5Damage and Forecast Modeling ¹

 

 

 

5.1. Introduction

The underlying issue that justifies a prognosis procedure is the implementation of maintenance policies or decision rules that take into account the history of the system, its environment, the diagnostic on its current state, and possibly the future operational conditions. Hence, we are placed straightaway in a context where online information must be integrated, and where decision rules are condition-based and/or dynamic with respect to this information. Thus, the aim is to exclude as much as possible decision-making from a mean behavior and to consider more delicate situations from the point of view of probabilistic approaches. Besides, we are often placed in a very operational approach, in the sense that we set a dynamic decision rule a priori and we look for tools enabling us to apply it by predicting the evolution of the system on a restricted horizon (by calculating the remaining useful lifetime in particular). In this framework, the use of models based on knowledge/learning makes sense and can happen to be better adapted and easier to implement than a probabilistic evolution model. On the contrary, on a more strategic level with an optimization point of view, it can be more useful to have at our disposal a mean performance criterion enabling us to optimize the possible decision rule(s), on an infinite horizon. A probabilistic approach will then certainly enable us to supply the required indicators. Hence, we ...