Ontologies of Time and Time-based Reasoning for MBSE of Cyber-Physical Systems

Our work is concerned with the development of Model-Based Systems Engineering (MBSE) procedures for the behavior modeling and design of Cyber-Physical Systems. This class of problems is defined by a tight integration of software and physical processes, the need to satisfy stringent constraints on performance, safety and a reliance on automation for the management of system functionality. To assure correctness of functionality with respect to requirements, there is a strong need for methods of analysis that can describe system behavior in terms of time, intervals of time, and relationships among intervals of time. Accordingly, this paper discusses temporal semantics and their central role in the development of a new time-based reasoning framework in MBSE for CPS. Three independent but integrated modules compose the system: CPS, ontology and time-reasoning modules. This approach is shown to be mostly appropriate for CPS for which safety and performance are dependent on the correct time- based prediction of the future state of the system. A Python-based prototype implementation has been created to demonstrate the capabilities of the ontological framework and reasoning engine in simple CPS applications.