In: International Journal of Advanced Manufacturing Technology, Vol. 14, No. 10, pages 704-715. 1998.
Abstract: The use of structure theory of Petri nets to develop efficient deadlock prevention and deadlock avoidance methods for flexible manufacturing systems (FMSs) modeled by (SR)-R-4 nets is demonstrated. Major synchronization patterns, such as generalized parallel and sequential mutual exclusion, frequently observed in FMS contexts can be represented by this class. The liveness property of a given (SR)-R-4 net (deadlock-freeness in the context of FMSs) is characterized in terms of structural Petri net elements called siphons. All efficient method for controlling minimal siphons of a given (SR)-R-4 net is developed where local control places are added to the net. A sufficient condition for liveness of the augmented net is provided. This constitutes a deadlock prevention approach. When the net liveness condition is not satisfied, an on-line controller, using a dynamic resource allocation policy, is developed for the augmented net. The performance of the proposed approaches is illustrated using several examples.
Keywords: Petri nets, deadlock avoidance, deadlock prevention, flexible manufacturing systems, structural theory.
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