Formal Modeling and Analysis of Distributed Measurement Systems in Cyber-Physical Systems Using Colored Petri Nets

Abstract

This research addresses the reliability and consistency challenges associated with the Cyber- Physical Systems (CPS) driven Distributed Measurement Systems (DMS), which capture, collect and process DMS data or information from measurement nodes located in various geo- graphical areas. Due to being distributed and asynchronous, these systems suffer from causal inconsistencies and synchronization delays, and unstable scheduling, thereby undermining dependency in fields like power management systems and smart grids. The first stage of this approach aims to obtain a formal specification of the DMS behaviour using Computation Tree Logic (CTL) and Linear Temporal Logic (LTL). These formal languages clearly capture safety and liveness properties like the absence of deadlock, safe power switching, reliable communication, safe and correct data processing, etc. The second stage of the approach is to build a system under study, a hierarchical Coloured Petri Net (CPN) model in CPN Tools1 using well-defined ColSets, functions, transitions, guards, and inter-page communication to simulate measurement power behaviour and control switching with respect to scheduling, measurement flow, and faults. An executable and semantically rich operational model of the system is obtained from this model. The final step validates the value of the CPN model with a detailed state-space analysis. State- space properties, such as boundedness, liveness, fairness, home-state behaviour, and Strongly Connected Component (SCC), are computed and compared to formal specifications. The analysis outcomes demonstrate that the modelled system fulfils all formalisms and performs acceptably from the system operational viewpoint within the analysed state space