Structural observability: Application to decompose a system with possible conflicts

Model based diagnosis of large continuous dy-namic systems requiring quantitative simulation has a high computational cost, which can be re-duced by distributing the computation. Distribu-tion can be obtained partitioning the original di-agnosis problem into the analysis of simpler sub-problems. In this work, Possible Conflicts are used to partition a system because they provide a systematic way to decompose a system. How-ever, a requirement of any decomposition method is that the resulting subsystems be observable. This paper focuses on structural observability, a powerful concept because it allows analyzing the observability of a system in terms of its config-uration, i.e., independently of system parameter values. However, the literature provides differ-ent definitions of structural observability, adapted to different modeling formalisms: equations, bi-partite graphs and bond graphs. This paper shows that definitions for these formalisms are equiv-alent. The three tank system benchmark and a spring-mass system are used to illustrate the def-initions and their equivalence. Then, it will be applied through Possible Conflicts to build inde-pendent subsystems that can be used for monitor-ing and diagnosis.