Hierarchical supervisory control of complex Petri nets

Somnath, Nisha

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https://hdl.handle.net/2142/29638 Copy

Description

Title

Hierarchical supervisory control of complex Petri nets

Author(s)

Somnath, Nisha

Issue Date

2012-02-06T20:08:11Z

Director of Research (if dissertation) or Advisor (if thesis)

Sreenivas, Ramavarapu S.

Department of Study

Aerospace Engineering

Discipline

Aerospace Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(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.

Graduation Semester

2011-12

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http://hdl.handle.net/2142/29638

Copyright and License Information

Copyright 2011 Nisha Somnath

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