IEEE CONTROL SYSTEMS SOCIETY TECHNICAL COMMITTEE
ON DISCRETE EVENT SYSTEMS

    Ryan J. Leduc
    Chair, IEEE CSS Technical Committee on DES
    Dept. of Computing and Software
    McMaster University
    1280 Main Street West
    Hamilton, Ontario
    Canada L8S 4K1

    Phone: (905) 525-9140 Ext. 27962
    Fax: (905) 524-0340
    e-mail: leduc@mcmaster.ca
    WWW: http://www.cas.mcmaster.ca/~leduc/

DESTC Web Page: http://www.cas.mcmaster.ca/destc/

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Contents:

1. Editorial


2. Journals
 2.1 Selections from International Journal of Control, Volume 83 Issue
     1, January 2010
 2.2 Selections from IEEE Transactions on Automatic Control, Volume: 54,
     Issue: 12, December 2009

Welcome to the newsletter of the IEEE Control Systems Technical Committee on Discrete Event Systems!

See http://www.cas.mcmaster.ca/destc/ for information on the DESTC.

Personal note from the editor:

Happy Holidays everyone!

Ryan

Contributed by: Ryan Leduc <leduc aht mcmaster doht ca>

SELECTIONS FROM INTERNATIONAL JOURNAL OF CONTROL
VOLUME 83 ISSUE 1
JANUARY, 2010

1) A new method for centralised and modular supervisory control of
real-time discrete event systems

Lucien Ouedraogo;  Ahmed Khoumsi; Mustapha Nourelfath 

Abstract: 

This article deals with the problem of controlling a plant described as
a real-time discrete event system (RTDES). In particular,
automata-based supervisory control of RTDES is addressed. The aim of
supervisory control is to restrict the behaviour (using a supervisor)
of an uncontrolled plant in order to conform to a given specification.
First, we propose a centralised method for the synthesis of a
supervisor that forces a given plant to conform to a given
specification. Then, we extend this centralised method to the modular
case, that is, for the synthesis of n supervisors that force the plant
to conform to n given specifications, respectively. Timed automata (TA)
with invariants is the model used to describe the plant and the
specification(s). The synthesis approach is based on the transformation
of the control problem into a non-real-time form, using a
transformation of TA into equivalent particular finite state automata
called Set-Exp-Automata. This transformation allows to adapt the theory
of Ramadge and Wonham, and is justified by the fact that it reduces the
state space explosion problem compared to other transformation methods
such as the transformation of TA into region automata. Moreover, the
Set-Exp-Automata model provides a suitable control architecture for
implementation. The proposed approach allows to obtain the solution to
both the centralised and modular supervisory control problem, by
identifying the solvability conditions and giving a step-by-step
computation procedure of the solution.

web site: click here

Contributed by: Ryan Leduc <leduc aht mcmaster doht ca>

SELECTIONS FROM IEEE TRANSACTIONS ON AUTOMATIC CONTROL
VOLUME: 54, ISSUE: 12
DECEMBER, 2009

1)  Verification of Nonconflict of Supervisors Using Abstractions

Pena, P. N.   Cury, J. E. R.   Lafortune, S.

Abstract: 

This paper presents an efficient test that uses abstractions to detect
conflict in composed systems controlled by local supervisors. This
test, called nonconflict test, is not applied over the languages
generated by the supervisors, but over abstractions of the supervisors
with some specific characteristics. The concept of observer and the
definition of the set of relevant events are the basis for the
approach. Two strategies to define the set of relevant events are
presented, along with illustrative examples. The paper also introduces
a combined strategy, which consists of applying the two strategies in
sequence leading, in many cases, to better reductions than when
applying each strategy independently. An example is presented to
illustrate the combined strategy.

web site: click here