Eastern Mediterranean University

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30 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

109 εμφανίσεις

Eastern Mediterranean University

Faculty of Engineering

Department of Mechanical Engineering



Agenda



Introduction



IEC

61499

Function

Block



Holonic

Manufacturing

System



Real
-
time

Distributed

Control

System



Reconfiguration

of

Real
-
time

Distributed

Control



Case

Study



Application

of

Virtual

Reality




Introduction



Manufacturing

control

systems

are

required

to

be

adaptive

and

responsive
.




One

approach

which

is

closely

related

to

the

Multi
-
agent

systems

is

HMS
.




The

motivation

is

the

requirement

for

manufacturing

systems

that

can

automatically

and

intelligently

adapt

to

changes

in

the

manufacturing

environment

while

still

achieving

overall

system

goals
.




Introduction



At

the

low

control

level

of

a

HMS,

especially

at

the

level

of

real
-
time

control,

reconfigurable

holonic

controllers

are

employed

(HCs)
.




The

critical

issue

for

holonic

control

at

this

level

is

how

the

resources

of

the

HMS

are

to

be

organized

dynamically

during

runtime

and

how

the

associated

controller

components

are

to

be

reconfigured

dynamically

at

the

same

time
.




Solution
:


Real
-
time

distributed

control

system

that

can

benefits

of

holonic

control

system
.






Introduction



The

real
-
time

holonic

distributed

control

systems

require
:




Stability

in

the

face

of

disturbance

(i,e
.
,

Sensor

or

Robot

Failure
.
)




Adaptability

and

flexibility

in

the

face

of

change
.




Efficient

use

of

available

resource
.



To

do

so,

IEC
-
1499

Function

block

(FB)

standard

is

employed
.






IEC
-
61499 Function Block


A

standardization

project

of

IEC

Technical

Committee

65

(TC
65
)

to

standardize

the

use

of

function

blocks

in

distributed

industrial
-
process

measurement

and

control

systems

(IPMCSs)
.


Work item approved 1991; assigned to Working Group 6 (WG6) 1993



Experts from USA, Germany, Japan, UK, Sweden, France, Italy



Also responsible for IEC 61131
-
3 (Programmable Controller
Languages) and 61131
-
8 (Programmable Controller Language
Guidelines)



IEC
-
61499 Function Block


Distributed applications


Event and data interfaces


Software encapsulation and reuse


Event
-
driven state machines


Service interfaces


Management services


Software portability



IEC
-
61499 Function Block

distributability

programmability

agility!

agility!

distributed

configurable

programmable

Common

Architecture

Reference

Model

Function Blocks

IEC 61499

Synthesis

PLC

IEC 61131
-
3

Centralized

Programmable

Configurable

Thesis

DCS

IEC 61804

Distributed

Configurable

Antithesis

dynamically

reconfigurable

= agile !



IEC
-
61499 Function Block


IEC

61499

is

composed

of

2

IECs

standards
:

IEC
-
61131
-
3

and

IEC
-
61804
.


IEC
-
61131
-
3

is

Centralized

Programming

Configurable

(PLC)

with

Distributablity

property
.


IEC
-
61804

is

Distributed

Configurable

with

Programmibility

property
.



The

result

is

Distributed

Configurable

Programmable

which

is

common

architecture

reference

model
.


IEC 61499


Parent organization
: IEC


Working group
: TC65/WG6


Goal
: Standard model
(function blocks) for control
encapsulation

& distribution


Started
: 10/90


Active development
: 3/92


Trial period
: 2001
-
03


Completion
: 2005


Holonic Manufacturing Systems
(HMS)


Parent organization
: IMS


Working group
: HMS
Consortium


Goal
: Intelligent manufacturing
through holonic (autonomous,
cooperative) modules


Feasibility study
: 3/93
-
6/94


First phase
: 2/96
-

6/00


Second phase
: 6/00
-
6/03

Requirements

Controls architecture

Intelligent Automation architecture



IEC
-
61499 Function Block

Output variables

Input variables

Event inputs

Event outputs

Algorithms

Type identifier

(IEC 1131
-
3)

Internal


variables

Execution


Control


Chart



IEC
-
61499 Function Block


Function

Block

is

consist

of

two

main

parts
:

Head

and

Body
.


The

head

of

Function

Block

is

Execution

Control

Chart

(ECC)

which

organizes

the

flow

of

events

between

the

blocks

as

well

as

the

body

control
.


The

body

of

Function

Block

consists

of

algorithm

and

the

internal

data

as

well

as

the

I/O

data
.


The

algorithm

inside

the

body

operates

in

IEC
-
61131
-
3

standards
.


The

body

will

control

the

resource

capabilities,

scheduling,

communication

and

process

mapping
.


Events

inputs

and

outputs

are

used

to

synchronize

function

blocks

within

an

application

and

to

schedule

the

algorithms

within

the

function

block
.


Data

inputs

and

outputs

are

the

interface

with

the

external

of

the

function

block

since

internal

data

is

hidden
.




IEC
-
61499 Function Block

Function Block Execution Model



IEC
-
61499 Function Block

1.
Relevant

data

input

values

are

made

available
.

2.
The

event

at

the

event

input

occurs
.

3.
The

execution

control

function

notifies

the

resource

scheduling

function

to

schedule

and

algorithm

for

execution
.

4.
Algorithm

execution

begins
.

5.
The

algorithm

completes

the

establishment

of

values

for

the

output

variables

associated

with

the

event

output
.

6.
The

resource

scheduling

function

is

notified

that

algorithm

execution

has

ended
.

7.
The

scheduling

function

invokes

the

execution

control

function
.

8.
The

execution

control

function

signals

an

event

at

the

event

output
.




Holonic Manufacturing System


Holon

is

an

autonomous

and

cooperative

building

block

of

a

manufacturing

system

for

transforming,

transporting,

storing,

and/or

validating

information

and

physical

objects
.


Holon

Autonomy

is

the

capability

of

a

holon

to

create

and

control

the

execution

of

its

own

plans

and/or

strategies
.


Holon

Cooperation

is

the

process

whereby

a

set

of

holons

develops

mutually

acceptable

plans

and

executes

them
.


Holon

Self
-
organization

is

the

ability

of

holons

to

collect

and

arrange

themselves

in

order

to

achieve

a

production

goal
.


Holarchy

is

system

of

holons

that

can

cooperate

to

achieve

a

goal

or

objective
.





Real
-
time Distributed Control

(Definitions)




System
:

A

collection

of

devices

interconnected

and

communicating

with

each

other

by

means

of

a

communication

network

consisting

of

segments

and

links
.



Device
:

An

independent

physical

entity

capable

of

performing

one

or

more

specified

functions

in

a

particular

context

and

delimited

by

its

interfaces
.



Resource
:

A

functional

unit

having

independent

control

of

its

operation,

and

which

provides

various

services

to

applications

including

scheduling

and

execution

of

algorithms
.



Application
:

A

software

functional

unit

that

is

specific

to

the

solution

of

a

problem

in

industrial
-
process

measurement

and

control
.

An

application

may

be

distributed

among

devices

and

may

communicate

with

other

applications
.



Real
-
time Distributed Control


A

holon

is

represented

by

one

or

more

hardware

devices

and

can

interact

via

one

or

more

communication

networks
.


Each

device

comprises

of

one

or

more

resources

(i
.
e
.

processor

with

memory)

and

one

or

more

interface
.


Interfaces

enable

the

device

to

interact

with

either

the

controlled

manufacturing

process

or

with

other

devices

through

a

communication

interface
.


Resources

are

logical

entities

with

independent

control

over

their

operations

including

the

scheduling

of

their

tasks
.


A

resource

can

be

created,

configured

via

management

model
.





Real
-
time Distributed Control



Applications

are

networks

of

function

blocks

(FB)

and

variables

connected

by

data

and

event

flows
.


Such

applications

aid

the

modeling

of

cooperation

between

the

autonomous

holons
.


Function

blocks

receive

event/data

from

interfaces,

process

them

by

executing

algorithms

and

produce

outputs,

all

handled

by

an

event

control

chart
.


Function

block

algorithms

can

be

written

in

high
-
level

programming

language

or

in

the

IEC
-
61131

language

for

PLCs
.




Reconfiguration of Real
-
time Distributed Control




In

conventional

PLC

systems,

reconfiguration

involves

a

process

of

first

editing

the

control

software

offline

while

the

system

is

running,

then

committing

the

change

to

the

running

control

program
.




When

the

change

is

committed,

severe

disruptions

and

instability

can

occur

as

a

result

of

high

coupling

between

elements

of

the

control

software

and

inconsistent

real
-
time

synchronization
.




Three

types

of

reconfiguration
:



Simple configuration utilizes the IEC 61499 model to avoid software
coupling issues during reconfiguration.



Dynamic reconfiguration uses techniques to properly synchronize
software during reconfiguration.



Intelligent reconfiguration exploits multi
-
agent techniques to allow the
system to reconfigure automatically in response to change.







Reconfiguration of Real
-
time Distributed Control


The Reconfiguration
Model



Reconfiguration of Real
-
time Distributed Control




Function

block

ports

(i
.
e
.
,

event

and

data

connections)

are

objects

that

register

with

the

Resource

Manager

(RM)

associated

with

the

function

block
.

The

resource

manager

looks

after

the

interconnection

of

function

block

ports

(i
.
e
.
,

as

is

specified

by

the

application)

and

maintains

a

record

of

all

function

block

ports

in

a

FB

Port

table
.




The

Device

Manager

(DM)

looks

after

the

interconnection

of

the

RM’s

function

block

ports

and

stores

this

information

in

an

RM

Port

table
.




Application

Manager

(AM)

looks

after

the

interconnection

of

the

DM’s

function

block

ports

and

stores

this

information

in

a

DM

Port

table
.




Reconfiguration of Real
-
time Distributed Control




The

advantage

of

this

approach

is

that

reconfiguration

can

be

managed

at

various

levels

(i
.
e
.
,

function

block,

resource,

device,

application)
;

all

that

is

required

is

a

“map”

of

the

new

configuration

(i
.
e
.
,

based

on

the

FB,

RM,

and

DM

Port

tables)
.




This

approach

allows

for

the

“basic

reconfiguration”

discussed

previously,

but

does

not

yet

address

how

dynamic

and

intelligent

reconfiguration

are

performed
.




The

fundamental

difference

between

basic

and

dynamic

reconfiguration

is

the

latter’s

recognition

of

timeliness

as

a

critical

aspect

of

correctness
.




Reconfiguration of Real
-
time Distributed Control




Intelligent

reconfiguration

builds

.
on

dynamic

reconfiguration

(i
.
e
.
,

timeliness

constraints)

by

focusing

on

multi
-
agent

techniques

to

allow

the

system

to

reconfigure

automatically

in

response

to

change
.



For

example,

as

part

of

a

fault

recovery

strategy,

higher
-
level

agents

will

manage

the

reconfiguration

process

using

diverse

or

homogeneous

redundancy
.



Two

approaches

to

achieve

these

more

advanced

forms

of

reconfiguration
:




Preprogrammed or “contingencies” approach.



Softwiring

approach.




Reconfiguration of Real
-
time Distributed Control




Contingencies

Approach




Contingencies

are

made

for

all

possible

changes

that

may

occur
.




Alternate

configurations

are

pre
-
programmed

based

on

the

system

designer’s

understanding

of

the

current

configuration,

possible

faults

that

may

occur

as

well

as

possible

means

of

recovery
.




Disadvantages
:




Inflexibility

particularly

with

respect

to

the

handling

of

unanticipated

changes
.



This

approach

would

require

constant

maintenance

in

order

to

keep

the

reconfiguration

tables

up

to

date
.










Reconfiguration of Real
-
time Distributed Control




Soft
-
wiring

Approach




FB,

RM,

DM

port

tables

are

connected

to

the

Configuration

Agent

(CA)
.



This

agent

has

information

of

how

two

FB,

RM

or

DM

can

be

connected
.



CA

will

use

this

information,

for

example,

to

connect

a

new

function

block

with

an

existing

function

block

or

to

replace

an

existing

one

with

a

new

while

ensuring

that

the

real
-
time

requirement

are

met
.





Advantages
:




It’s

potential

to

overcome

the

inflexibility



It’s

potential

to

realize

intelligent

reconfiguration
.











References


Brennan,

R
.
W
.


Fletcher,

M
.


Norrie,

D
.
H
.



Reconfiguring

Real
-
Time

Holonic

Manufacturing

Systems
”,

Proceedings

of

the

12
th

International

Workshop

on

Database

and

Expert

Systems

Applications,

Page

611
,

2001
.


Vrba
,

P
.


Marik
,

V
.

,


Simulation

in

agent
-
based

manufacturing

control

systems
”,

2005

IEEE

International

Conference

on

Systems,

Man

and

Cybernetics,

page(s)
:

1718
-

1723

Vol
.

2
,

Oct
.

2005
.


Xiaokun

Zhang


Norrie,

D
.
H
.


Brennan,

R
.
W
.


Yuefei

Xu
,

“A

multi
-
level

reconfiguration

control

for

holonic

PLC”

,

2000

IEEE

International

Conference

on

Systems,

Man,

and

Cybernetics,

page(s)
:

1762
-
1767

vol
.
3
,

2000
.


Xiaokun

Zhang

Sivaram

Balasubramanian

Robert

W
.

Brennan

Douglas

H
.

Norrie,

“Design

and

implementation

of

a

real
-
time

holonic

control

system

for

manufacturing”,

Information

Sciences

Applications
:

An

International

Journal,

Volume

127

,


Issue

1
-
2


(Aug
.

I

2000
)
.






References


M
.
Bal
,

M
.

Hashemipour
,

“Applications

of

Virtual

Reality

in

Design

and

Simulation

of

Holonic

Manufacturing

Systems
:

A

Demonstration

in

Die
-
Casting

Industry”
,

Proceedings

of

the

3
rd

international

conference

on

Industrial

Applications

of

Holonic

and

Multi
-
Agent

Systems
:

Holonic

and

Multi
-
Agent

Systems

for

Manufacturing,

Pages
:

421



432
,

2007
.


Rockwell

Automation

Company,


IEC

61499

Function

Block

Model
:

Application

Note
”,

www
.
isagraf
.
com
,

April

2008
.


James

H
.

Christensen,

“The

IEC

61499

Standard
:

Concepts

and

R&D

Resources”,

http
:
//www
.
rockwell
.
com

http
:
//www
.
holobloc
.
com
.