This paper identifies a property of delay-robustness in distributedsupervisory control of discrete-event systems (DES) with communication delays.In previous work a distributed supervisory control problem has beeninvestigated on the assumption that inter-agent communications take place withnegligible delay. From an applications viewpoint it is desirable to relax thisconstraint and identify communicating distributed controllers which aredelay-robust, namely logically equivalent to their delay-free counterparts. Forthis we introduce inter-agent channels modeled as 2-state automata, compute theoverall system behavior, and present an effective computational test fordelay-robustness. From the test it typically results that the given delay-freedistributed control is delay-robust with respect to certain communicatedevents, but not for all, thus distinguishing events which are notdelay-critical from those that are. The approach is illustrated by a workcellmodel with three communicating agents.
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