University of Illinois Urbana-Champaign

Disjunctive normal formula based supervisory control policy for general Petri nets

Deverakonda, Vijayalakshmi

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Vijayalakshmi_Deverakonda.pdf

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https://hdl.handle.net/2142/50715

Description

Title
Disjunctive normal formula based supervisory control policy for general Petri nets
Author(s)
Deverakonda, Vijayalakshmi
Issue Date
2014-09-16
Director of Research (if dissertation) or Advisor (if thesis)
Sreenivas, Ramavarapu S.
Department of Study
Industrial&Enterprise Sys Eng
Discipline
Industrial Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Date of Ingest
2014-09-16T17:25:36Z
Keyword(s)
Petri Nets
Abstract
A Petri net (PN) is said to be live if it is possible to re any transition, although not immediately, from every reachable marking. A liveness enforcing supervisory policy (LESP) determines which controllable transition is to be prevented from ring at a marking, to ensure the supervised Petri net (PN) is live. A LESP is said to be minimally restrictive if the following property is true { if a minimally restrictive LESP prevents the ring of a transition at a marking, then all other LESPs should do the same. We restrict our attention to a class of general Petri nets (PN) structures, where the existence of an LESP for an instance initialized at a marking, implies the existence of an LESP when the same instance is initialized with a larger initial marking. We show that the minimally restrictive LESP for an instance N from this class is characterized by a collection of boolean formulae f tc(N)gtc2Tc , where Tc is the set of controllable transitions in the PN. The literals in tc(N) are true if and only if the token-load of speci c places meet a threshold. Consequently, appropriately placed threshold-sensors, which detect if the token-load of a place is greater than or equal to a predetermined threshold, provide su cient information to implement the minimally restrictive LESP.
Graduation Semester
2014-08
Permalink
http://hdl.handle.net/2142/50715
Copyright and License Information
Copyright 2014 Vijayalakshmi Deverakonda

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