HIERARCHICAL TIME-EXTENDED PETRI NETS (H-EPNS) BASED ERROR IDENTIFICATION AND RECOVERY FOR MULTILEVEL SYSTEMS

In this paper, Hierarchical Time-Extended Petri Nets (H-EPN's), an ext ended Petri net based modeling and analysis tool, are used to derive t he coordination level [10], [13] model of hierarchically decomposable systems, viewed from a three-level hierarchical structure of organizat ion, coordination and execution of tasks. A two-layer (vertical) coord ination level framework, consisting of the dispatcher/analyzer and the H-EPN controller is presented. A detailed two sub-level (horizontal) H-EPN controller model is derived to model system operations (includin g system soft failures). Error classification based on the interaction between the various system coordinators is derived from the H-EPN mod el. The H-EPN approach preserves multi-resolutional system details as well as effective communication flows between the various subsystems. A simple example illustrates the proposed approach. The important H-EP N properties of boundedness, safeness and reversibility are verified.