Eric Niel

Generalization of DES Multi-Modeling

Abstract DES multi-mode ling appears to be well adapted to management of production system operating modes. Associating a specific model of the process to be controlled and its specifications is in fact natural. However, conceptual problems involving the control aspect may arise, when an admissible distinctive behavior set is specified without considering the ensuing complexity. The aim of this paper is to specify and validate formally operating mode management under generalized conditions. Basically, the paper extends the model commutation problem (process-limited) from one-to-one to one-to-all. Its main results concern the generalized tracking mechanism for a different process behavior combination.

Fault Tolerant Systems: A State Approach to the Failure Recovery for the Timed Discrete Event Systems

Abstract In this paper a state approach to the failure recovery for the timed discrete event systems (TDES) is investigated. The system is assumed to be characterized by two functioning modes, the nominal and the degraded functioning modes. Assuming that detection and identification of failure events have been performed, to ensure system service continuity under an accepted risk, two failure recovery procedures are proposed. These procedure are introduced on the basis of the stability and stabilizability notions in control theory.