Specification and verification of real-time requirements of fault diagnosis

In some physical systems, fault detection and isolation (FDI) tasks have hard real-time constraints as a result of small time constants, large number of fault sources, fault propagation process and complexity of computation. In many cases, after fault diagnosis control system musts be reconfigured/restructured to avoid damages and continue their operation. Reconfiguration and restructuring process also requires some additional time that adds further timing constraints to the existing ones. Designing control systems with diagnosis and fault tolerance functions harden requirements of control processes because diagnosis and fault tolerance processes have to be taken into account. We introduce notions of single fault, multiple faults and fault propagation diagnosis times. We discuss modelling of functional and structural properties of diagnosis system. We describe fault models, fault subpaths and their behavioural properties and then build Petri net-based fault model to specify and verify its behaviour and constraints. The fault model is decomposed into fault subpaths. We expand Petri net-based fault model by time and define fault propagation times and fault diagnosis time consequently by an algorithm.