Eastern Mediterranean University
Faculty of Engineering
Department of Mechanical Engineering
Presented By:
Reza ABRISHAMBAF
Faezeh YEGANLI
 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
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Let’s have a look at PLC first!!
Prepared By: Abrishambaf, Yeganli
 Introduction
• A programmable logic controller (PLC) or programmable
controller is a digital computer used for automation of
mechatronic processes, such as control of machinery on
factory assembly lines.
• Designed for Multiple Input Multiple Output (MIMO).
• Fixed I/O or Modular I/O
Prepared By: Abrishambaf, Yeganli
 Introduction
• SIEMENS S7-200, CPU 222.
• 8 Inputs, 6 Outputs.
• 256 Counters & Timers.
Prepared By: Abrishambaf, Yeganli
 Introduction
Prepared By: Abrishambaf, Yeganli
 IEC-61499 Function Block
•
•
A standardization project of IEC Technical Committee 65 (TC65) 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)
Prepared By: Abrishambaf, Yeganli
 IEC-61499 Function Block
•
•
•
•
•
•
•
Distributed applications
Event and data interfaces
Software encapsulation and reuse
Event-driven state machines
Service interfaces
Management services
Software portability
Prepared By: Abrishambaf, Yeganli
 IEC-61499 Function Block
Centralized
Programmable
Configurable
PLC
IEC 61131-3
Thesis
agility!
distributability
Function Blocks
IEC 61499
Synthesis
Antithesis
DCS
IEC 61804
programmability
agility!
dynamically
reconfigurable
= agile !
Common
Architecture
Reference
Model
distributed
configurable
programmable
Distributed
Configurable
Prepared By: Abrishambaf, Yeganli
 IEC-61499 Function Block
•
•
•
•
IEC 61499 is composed of 2 IECs standards: IEC-61131-3 and IEC61804.
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.
Prepared By: Abrishambaf, Yeganli
•
•
•
•
•
•
•
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
Prepared By: Abrishambaf, Yeganli
 IEC-61499 Function Block
Event inputs
Event outputs
Execution
Control
Chart
Type identifier
Algorithms
(IEC 1131-3)
Internal
variables
Input variables
Output variables
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 IEC-61499 Function Block
Function Block Execution Model
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 Reconfiguration of Real-time Distributed Control
The Reconfiguration
Model
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 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.
Prepared By: Abrishambaf, Yeganli
 Case Study
System 1
Conveyor
5-joints Robot
Barcode Reader
Infrared Sensor
Prepared By: Abrishambaf, Yeganli
 Case Study
• System 1 contains Conveyor, Robot, Barcode Reader and Sensor.
• At the beginning of the conveyor, there is a switch. When a part touch the
switch, the conveyor will start.
• When a part comes to the system, it will be moved by conveyor. There is a
barcode reader will read the code of the part.
• Depending on the code of the part, the Robot will put it in either Machine 1
or Machine 2 or to the Conveyor 2 of the system 2.
Prepared By: Abrishambaf, Yeganli
 Case Study
System 2
Conveyor
5-joints Robot
Color Sensor
Pneumatic Robot
Infrared Sensor
Prepared By: Abrishambaf, Yeganli
 Case Study
• System 2 contains Conveyor, Robot, Pneumatic Robot, Color Sensor and
Infrared Sensor.
• The system waits until a part from system 1 arrives.
• When infrared sensor detects a part, the conveyor will start.
• Part will be moved till the color sensor, beside the color sensor, we have
pneumatic robot that will take the part or it will be moved until the infrared
sensor detects it.
• By detecting with infrared sensor, the robot will take and put the part in
another machine.
Prepared By: Abrishambaf, Yeganli
Prepared By: Abrishambaf, Yeganli
 Case Study (Reconfiguration)
Adding a Robot
Configuration
Agent
Cell 2
CA
Cell 1
Robot
Prepared By: Abrishambaf, Yeganli
 Case Study (Reconfiguration)
 Methods
of Adding a Robot
• To use the common method (Offline Mode).
• To use the predicted table.
• To use the IEC 61499 FB Standard.
Prepared By: Abrishambaf, Yeganli
 Case Study (Reconfiguration)
 Adding
a Robot
• The aim is to add one Robot the system.
• Cell 1 & Cell 2 have their own Function Blocks (FB1, FB2,….).
Function blocks will have information on how they can be connected (i.e.,
their interfaces) that is stored by CAS. The CAS will use this information, for
example, to connect a new function block with an existing function block or
to replace an existing function block with a new one while ensuring that the
application’s real-time requirements are met during the reconfiguration
process. The primary advantage of this approach is its potential to overcome
the inflexibility of the contingencies approach as well as its potential to
realize intelligent reconfiguration.
Prepared By: Abrishambaf, Yeganli
 Case Study (Reconfiguration)
For example, if the request for a new configuration requires upgrading an
application to include more sophisticated functionality, and the device does
not have sufficient processing resources for this upgrade, the new
functionality may have to be out-sourced.
Moreover, even if the execution of the function blocks’ tasks are consistent
with the device’s schedule and equipment, the device actor might still decide
to out-source some or all of the new configuration’s tasks. For example, this
redistribution may be done to save some of the available resources for
executing tasks associated with a configuration that is currently under
negotiation with the user.
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
In this section three simulation softwares will be presented.
 Virtual Reality
 Rockwell Simulation Model
 MAST (Manufacturing Agent Simulation Tool)
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
• The Design Environment includes the Multi Agent System Model.
• The agents are AGVs, Robots, Conveyor,…
• The messaging system is based on JAVA/JADE.
• What if each agent is defined based on IEC 61499 Function Block?
FB
FB
FB
Conveyor
AGV
Robot
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
Proposed Multi Agent System
Based on IEC 61499
Configuration
Agent
Header
Body
AGV
Header
Header
Body
Body
Robot
Conveyor
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
• The agents are defined based on IEC 61499 FB.
• The headers of Function Blocks are connected to the Configuration Agent.
• The Configuration Agent (CA) contains the status of each Function Block
and the connection among them.
• This configuration system can be based on JAVA/JADE or other high level
languages.
• In case of device failure, since CA has the status of the FBs, it can
substitute another device instead.
• The whole system is in the Design Environment.
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
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 interfaces.
Interfaces enable the device to interact with either the controlled
manufacturing process (via a process interface) 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 etc (as part of the system’s life-cycle) via a management model.
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
Applications (software functional units spanning one or more resources and
over one or more devices) 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 blocks’ algorithms can be written in either high-level programming
languages (e.g., C++) or in the IEC 61 131 languages for programmable
controllers (e.g., Ladder Diagrams, Structured Text). A distribution model
controls how applications are decomposed while ensuring that every
function block is an atomic unit of distribution.
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
Another
Simulation
Model
proposed by Rockwell Co.
It represents a new approach to
the manufacturing oriented agent
based control and simulations
that enables the integration of
agents with the currently used
industrial
control
hardware
architecture and simplifies the
transfer of the agent-control
developed initially for simulation
purposes to the actual physical
control.
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
• Physical Process: is the physical entity like AGV, Robot.
• PLC: contains Data Table which has the status of each physical entity in
the Tags(A1_tagA, A1_tagB).
• Agent Control: contains the corresponded Physical Component Agent.
• Emulation: used to simulate the system , like Matlab, Arena.
• Visualization: providing graphical view of the system.
• By the combinations of the mentioned blocks, an Agent Based Simulation
System will be obtained.
Prepared By: Abrishambaf, Yeganli
 Advantage of Virtual Reality
• One of the important advantages of such a real time system is that the
system can be reconfigured online.
For instance, when a new sensor is added at runtime to the conveyor based
transportation system, a set of new elements are dynamically created and
added to corresponding subsystems sharing the data-table: the sensor
agent is added to the agent control part, the sensor emulation unit is added
to the emulation subsystem and the sensor visualization element is added to
the visualization module. Concurrently, the tag values corresponding to the
state of the sensor are added to the data-table to be shared by these new
elements.
Prepared By: Abrishambaf, Yeganli
 Advantage of Virtual Reality
Another Advantage:
The important feature of the proposed interface is smooth shift of the control
functionalities from the agent based simulation towards the real-life control.
It allows replacing of the emulation subsystem with the real physical
manufacturing equipment by preserving the same tag names referring to the
sensor and actuator values. Thus it is not necessary to do any modifications
in the agents or in the visualization subsystem.
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
MAST (Manufacturing Agent Simulation Tool)
As result of the research effort under the Intelligent Manufacturing Systems
(IMS) framework Rockwell Automation in cooperation with different partners
has designed and developed MAST (Manufacturing Agent Simulation Tool) a
graphical visualization tool for multi agent systems. The main target is the
materials handling domain and it is built on the JADE standard FIPA
platform. In MAST, the user is provided with the agents for basic material
handling components as for instance manufacturing-cell, conveyor belt,
diverter and AGVs. The agents cooperate together via message sending
using common knowledge ontology developed for material handling domain.
Prepared By: Abrishambaf, Yeganli
 Application of Virtual Reality
MAST (Manufacturing Agent Simulation Tool)
MAST represents the state of the art in graphical simulation tools for
modeling and simulation of multi agent systems in manufacturing control,
however and due to the fact that only material handling systems are
targeted the tool does not cover complex application from a 3-D geometric
viewpoint such as the robotic manipulation.
Prepared By: Abrishambaf, Yeganli
 Advantage of Virtual Reality
Virtual Reality in Real-time system:
1. Solving problems before being employed in practical manufacturing.
2. Preventing costly mistakes.
3. Online analysis of reconfiguration before being engaged to the reality.
4. De-centralized manufacturing control architecture.
5. MAST & Rockwell Model are simulation models, it means that there is no
re-configurability control, however in VR reconfiguration can be
performed.
Prepared By: Abrishambaf, Yeganli
 Advantage of Virtual Reality
One of the most important advantage of VR in real time is online analysis.
For instance, in a system, one robot needs to be reconfigured. With the help
of function block, the reconfiguration can be performed in real time, however
what if this reconfiguration is inconsistent with the system. By using virtual
reality, the reconfiguration in virtual environment can be performed to
observe any inconsistency.
Another example can be the addition of a sensor. Recall that adding a
physical entity would require a new function block. This new function block
will be added using Configuration Agent. In VR this sensor will be added to
the system to see how the other parts will adapt their selves to this new
configuration. If a resource is not be able to adapt itself to new configuration,
there will be failure in whole system.
Prepared By: Abrishambaf, Yeganli
 References
 Brennan, R.W. Fletcher, M. Norrie, D.H. ” Reconfiguring Real-Time
Holonic Manufacturing Systems”, Proceedings of the 12th
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).
Prepared By: Abrishambaf, Yeganli
 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 3rd
international conference on Industrial Applications of Holonic and MultiAgent 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.
Prepared By: Abrishambaf, Yeganli
Descargar

PLC & Real time Holonic Control