CAUSALITY OF THE RESIDUAL STRUCTURE

This paper discusses some issues associated to the generation of the residual structure for fault detection and isolation using graph theory tools. It is shown that the residual structure of a causal dynamic system is as well causal, since a complete matching is only manipulation of internal variables of the graph. Then, no additional conditions are required during the matching process to get causal analytical redundancy relations. Moreover, the consideration that at least a pair of known variables, cause-effect, is necessary for each matching reduces substantially the number of cases which allows to span the residual structure.