On the notion of maintenance state for industrial assets

Maintenance is vital to ensure our manufacturing assets operate safely and efficiently. Maintenance work is triggered by a number of factors. One of these factors is a change in health state of an asset and the impact of this change on the ability of the asset to perform its functions. In addition, the act of performing maintenance changes the health state of the asset, restoring or retaining it to a state in which it can perform its required function. The ability to perform maintenance can also depend on the state, up state or down state, of the asset. The notion of state and the precursors and consequence of a change in state of an asset are central to developing formal maintenance ontologies and their related reasoning mechanisms to support maintenance management process automation. This paper explores this notion in a Basic Formal Ontology (BFO) context using an illustrative case study. In modelling a simple example, we have encountered many issues that are under active discussion within the industrial ontology community. We propose a formalization for maintenance state and discuss practical and ontological issues. Our main focus is on the role of maintenance state in the interplay between function realization and process participation, conditioned on a state. The paper is a call-to-arms to the ontology community to engage with defining a notion of state to support the use of ontologies and reasoning to assist in automation of industrial manufacturing processes.