engleski

Design of River System Deadlock Avoidance Supervisor by using Petri net

Advanced function of the computer based river traffic management system should automatically predict and prevent possible conflict and deadlock states between vessels by using adequate control policy (supervisor). This paper proposes a formal method for calculating maximally permissive deadlock prevention supervisor. To model the river system, the authors use a class of Petri net suitable for describing multiple re-entrant flowlines with disjoint sets of resources, jobs and control places, and matrix based formal method to analyze system. By using matrix algebra, authors analyze the structural characteristics of the Petri net (circular waits, P-invariants, critical siphons and subsystem, key resource) and propose the steps for supervisor design. First and second level deadlocks can be avoided by maintaining the number of tokens in the critical subsystems and ensuring that the key resource would not be the last available resource in the system. The derived supervisor is verified by a computer simulation using MATLAB environment.

Traffic management system; Deadlock avoidance; Discrete event system; Petri net

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