Ontological Methods of Functional Analysis for Aerospace Concepts

Functional analysis and decomposition are crucial steps in the development of complex aerospace systems, involving the translation of high-level system requirements into high-level functions, their breakdown into lower-level functions, and linking these functions to system elements. Traditionally, these processes are conducted informally, relying on the engineering judgment of developers, which may limit consistency and reduce the potential for automated assistance. To formalize these processes, we propose using an ontology-a structured conceptualization of terms and relations within a domain. This paper presents a function sub-ontology, part of an ongoing ontology development effort in association with the Advanced Concepts Office at Marshall Space Flight Center, aimed at modeling early stage space system concepts. The function sub-ontology defines types of functions, their interactions, and decomposition rules using the Ontological Modeling Language (OML). This structured approach supports automated reasoning, facilitating more consistent and traceable functional decomposition. The ontology's reasoning capabilities are demonstrated through several examples, showcasing its utility in space system concept development. These examples highlight how the ontology can help ensure consistency between functions, determine equivalence of functions, suggest functional decompositions, and recommend necessary system elements. While the ontology shows promise in enhancing functional analysis in aerospace systems, it is a work in progress. Future work will focus on refining the formal theory underpinning the ontology and further expanding its capabilities.