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Title:Hierarchical supervisory control of complex Petri nets
Author(s):Somnath, Nisha
Advisor(s):Sreenivas, Ramavarapu S.
Department / Program:Aerospace Engineering
Discipline:Aerospace Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Petri nets
Supervisory control
Concurrent systems
Abstract:Large, complex systems are prone to the phenomenon of livelocks. Once a system enters a livelocked-state, there is at least one activity of the modeled system that cannot be executed from all subsequent states of the system. This phenomenon is common to many operating systems where some process enters into a state of suspended animation for all perpetuity, and the user is left with no other option than to forcibly kill the suspended job, or reboot the machine. This thesis is about finding supervisory control policies that enforce livelock-freedom in large complex systems that are modeled using Petri nets. The supervisory policy, when it exists, prevents the occurrence of certain events (i.e. activities) at specific states in such a way that the supervised system is livelock free. A hierarchical approach is used to find a supervisory policy for petri nets. This theory finds application for concurrent systems like computer operating systems which are complex to analyze. The complex system is (recursively) represented as the combination of two smaller systems. Under favorable conditions identified in this thesis, local supervisory policies that enforces livelock-freedom in each of the smaller systems will suffice to enforce livelock-freedom in the larger system.
Issue Date:2012-02-06
Genre:Dissertation / Thesis
Rights Information:Copyright 2011 Nisha Somnath
Date Available in IDEALS:2012-02-06
Date Deposited:2011-12

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