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. Books
 2.1 Supervisor Localization: A Top-Down Approach to Distributed Control of
     Discrete-Event Systems", by Kai CAI

3. Conferences
 3.1 1st MONTREAL WORKSHOP ON  IDEMPOTENT AND TROPICAL MATHEMATICS,
     Montreal, Canada, June 27 - 30, 2009

4. Journals
 4.1 Selections from Automatica, Volume 45, Issue 5, May 2009
 4.2 Selections from International J. of Advanced Manufacturing
     Technology, Volume 41, Numbers 11-12, April 2009
 4.3 Selections from IEEE Transactions on Systems, Man, and Cybernetics,
     Part C: Applications and Reviews, Volume: 39, Issue: 2, March
     2009
 4.4 Selections from IEEE Transactions on Systems, Man, and Cybernetics,
     Part C: Applications and Reviews, Volume: 39, Issue: 3, May
     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:

Welcome to the May 2009 DESTC newsletter,

Ryan 

Contributed by: Ryan Leduc <leduc aT mcmaster dOT ca>

SUPERVISOR LOCALIZATION: A TOP-DOWN APPROACH TO DISTRIBUTED CONTROL OF
DISCRETE-EVENT SYSTEMS

Kai CAI
University of Toronto, MASc Thesis, 2008
ISBN N/A
http://www.control.toronto.edu/people/profs/wonham/wonham.html

  We study distributed control design for discrete-event systems (DES)
in the framework of supervisory control theory. Our DES comprise
multiple agents, acting independently except for specifications on
"global" behavior. The central problem investigated is how to
synthesize "local" controllers for individual agents such that the
resultant controlled behavior is identical with that achieved by global
supervision.

  The investigation is carried out with both language- and state-based
models. In the language-based setting, a supervisor localization
algorithm is developed that solves the problem in a top-down fashion:
frst, compute a global supervisor, then decompose it into local
controllers. For large-scale DES where a global supervisor might not be
feasibly computable owing to state explosion, a
decomposition-aggregation solution procedure is established. In the
state-based setting, specifically that of "state tree structures" (STS),
a counterpart supervisor localization algorithm is developed having
potential to exploit the known eficiency of STS for large-DES control
design.


See also:

K. Cai and W. M. Wonham, Supervisor Localization: A Top-Down Approach
to Distributed Control of Discrete-Event Systems,  AIP Conf. Proc.,
March 5, 2009, Volume 1107, pp. 302-308
INTELLIGENT SYSTEMS AND AUTOMATION: 2nd Mediterranean Conference on
Intelligent Systems and Automation (CISA'09);

Contributed by: Ryan Leduc <leduc aT mcmaster dOT ca>

1ST MONTREAL WORKSHOP ON IDEMPOTENT AND TROPICAL MATHEMATICS
Montreal, Canada
June 27 - 30, 2009

Centre de Recherches Mathematiques (CRM) of the University of Montreal
and GERAD

The aim of this workshop is to bring together researchers in the domain
of tropical mathematics and its applications to mathematical physics,
and modeling, control and optimization of discrete event systems.

 MAIN TOPICS:

    * Tropical Algebra and Mathematical Physics
      and their Applications;
    * Tropical Geometry and its Applications. 

Including:

    * Idempotent analysis;
    * Idempotent functional analysis;
    * Tropical geometry and algebra;
    * Tropical and idempotent convex geometry;
    * Mathematics of idempotent semirings;
    * and their applications;
    * Quantization, dequantization, and related topics
      of mathematical physics. 

 There will be two types of talks:

    * 1 hour talk (50 min + 10 min discussion)
    * 30 min talk (25 min + 5 min discussion) 

Official languages of the workshop: English and French 


IMPORTANT DEADLINES:

March 1: Preliminary title of the talk, together with an indication of
preferences (60 min or 30 min talk)

April 24: Extended abstract in LaTex (12 pt, up to 5 pages)

May 6: Notification of acceptance

June 1: Registration

web site: click here

Contributed by: Ryan Leduc <leduc aT mcmaster dOT ca>

SELECTIONS FROM AUTOMATICA
VOLUME 45, ISSUE 5
MAY, 2009

1) 
Delay-coobservability and its algebraic properties for the
decentralized supervisory control of discrete event systems with
communication delays

Seong-Jin Park, Kwang-Hyun Cho

Abstract:

In networked control systems, uncontrollable events may unexpectedly
occur at a plant before a proper control command is applied to it due
to communication delays. In this paper, we address the problem of
decentralized supervisory control under such communication delays based
on the C&P (conjunctive and permissive) and D&A (disjunctive and
antipermissive) decision architecture. In particular, for the existence
of a decentralized supervisor, we present the notion of
delay-coobservability of a given language specification and a
polynomial-time algorithm for verifying it. In addition, algebraic
properties of the delay-coobservability are investigated. We further
present a synthesis method of the decentralized supervisor for
practical usefulness.

web site: click here

Contributed by: Ryan Leduc <leduc aT mcmaster dOT ca>

SELECTIONS FROM INTERNATIONAL J. OF ADVANCED MANUFACTURING TECHNOLOGY
VOLUME 41, NUMBERS 11-12
APRIL, 2009

1) A structural approach to the non-blocking supervisory control of
discrete-event systems

Lei Feng, Kai Cai and W. M. Wonham  

Abstract:

Many practical and important systemic properties of manufacturing
systems, like deadlock freeness, liveness, and reversibility, can be
formulated as the non-blocking property of discrete-event systems. It
can be difficult, however, to verify non-blocking or design a
supervisor to guarantee non-blocking control because of state size
explosion in the concurrency model. In this paper, we present
sufficient conditions for the computation of (small) model abstractions
that preserve the non-blocking property. As a consequence, hierarchical
and decentralized control structures can be flexibly integrated, and
the proposed approach can synthesize maximally permissive and
non-blocking control with reduced computational effort. The solution is
a group of decentralized supervisors that transparently displays
control logic and admits relatively simple implementation.

web site: click here

Contributed by: Ryan Leduc <leduc aT mcmaster dOT ca>

SELECTIONS FROM IEEE TRANSACTIONS ON SYSTEMS, MAN, AND CYBERNETICS,
PART C: APPLICATIONS AND REVIEWS
VOLUME: 39, ISSUE: 2
MARCH, 2009

1)  A Divide-and-Conquer Strategy to Deadlock Prevention in Flexible
Manufacturing Systems

ZhiWu Li   Sen Zhu   MengChu Zhou

Abstract:

Petri nets are a popular mathematical tool to investigate the deadlock
problems in resource allocation systems. As an important problem
solution paradigm in computer science, the divide-and-conquer strategy
is used in this paper to investigate the deadlock prevention for
flexible manufacturing systems (FMSs) that are modeled with Petri nets.
Based on the concept of resource circuits, a plant net model is divided
into an idle subnet, an autonomous subnet, and a number of small but
independent subnets, called toparchies, from the viewpoint of deadlock
control. A liveness-enforcing supervisor, called toparch, is designed
for each toparchy. If a particular separation condition holds in a
plant net model, the computational complexity of toparches is
significantly reduced. This research shows that the resultant net,
called monarch, by composing the toparches derived for the toparchies
can serve as a liveness-enforcing Petri net supervisor for the whole
plant model. FMS examples are given to illustrate the proposed method.

web site: click here

Contributed by: Ryan Leduc <leduc aT mcmaster dOT ca>

SELECTIONS FROM IEEE TRANSACTIONS ON SYSTEMS, MAN, AND CYBERNETICS,
PART C: APPLICATIONS AND REVIEWS
VOLUME: 39, ISSUE: 3
MAY, 2009

1)  Study on Road Network Traffic Coordination Control Technique With
Bus Priority

Guojiang Shen; Xiangjie Kong

Abstract:

On the basis of distributed traffic control framework, fuzzy theory,
and artificial neural networks technique, the road network traffic
intelligent coordination control technique with bus priority was
proposed. The whole road network was regarded as a large-scale system,
and the subsystems were the intersections. Multiphase intelligent
signal controller that controlled its own traffic and cooperated with
its neighbors was installed at each intersection. By exchanging
information collected from its social vehicle detectors and the bus
detection and location devices, and cooperating with adjacent signal
controllers, social vehicle coordination and bus priority in the whole
road network were realized. Bus priority module, green observation
module, and phase switch module comprised the hard core of the
controller. In each module, the fuzzy rule base system was designed in
detail. To improve the control system's robusticity, the fuzzy
relations of the three modules were implemented by one neural network.
The target of this proposed method was to maximize the possibility for
vehicles to depart from the upstream intersection, and the traveling
bus nearby the local intersection to pass the local intersection
without stoppage while the utility efficiency of the green signal time
was at a relatively high level. The actual application shows that the
proposed method can decrease the average vehicle delay and average
travel time effectively.

web site: click here