Eastern Mediterranean University Faculty of Electrical and electronic Engineering Supervisor : Reza abrishambaf Reza gholizadeh Mohammadhossein dadfar Supervisor : Reza abrishambaf Reza gholizadeh Mohammadhossein dadfar

Out line  Introduction  Holonic Manufacturing System  Real-time Distributed Control System  Reconfiguration of Real-time Distributed Control  Case Study

Introduction  Manufacturing control systems are required to be adaptive and responsive.  HMS is One approach which is closely related to the Multi- agent systems.  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.

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  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.  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 language for PLCs.

Real time holonic control architecture

DRES Requirements: there are several opportunities to use embedded computing systems in advanced industrial applications. However, in order to be applicable to industrial applications, DRES have to meet following requirements:  Dependability: it is usually defined as that property of a computer system such that reliance can justifiably be placed on the service it delivers. Both for economical (for instance, high costs of breakdown time) as well as for safety reasons, dependability is a key concept that must be supported by DRES when applied to industrial applications.  Real-time communication: most manufacturing systems are physically distributed over a plant site, so that that their embedded system components will also be physically apart. In order to be able to interact and synchronize while meeting stringent timing requirements, real-time industrial communication protocols must be employed, so that a timely communication occurs.

DRES Requirements:  Flexibility/reconfigurability/agility: future manufacturing and industrial processes will exhibit much higher degrees of physical reconfigurability in order to accommodate frequent changes in product mix and volume, as well as due to frequent introduction of new product types and manufacturing technology. In addition, rapid reconfiguration will be used much more frequently to recover from machine and process faults with minimal loss of production. In all these cases, the control system (hardware and software) must be quickly reconfigured, and for the most part automatically so, in order not to become a bottleneck to agility.  Modularity: in order to support the above-mentioned requirements of adaptability, DRES must be constructed in a modular way. Modularity also affects serviceability and recyclability in terms of disassembly, separation, repair, and reprocessing.

DRES Requirements:  Openness: a system is defined as open when the implementations of its components conform to an (non- proprietary) interface specification such that upgrading and customization of the system as well as integration of new components is possible.  Location transparency: communication among different nodes should use names that are not dependent on user’s or resource’s location. This becomes particularly important when mobile devices/equipment, such as AGVs, are used.  Autonomous behaviour: a key issue in intelligent manufacturing systems is the capability of manufacturing devices in autonomously making decisions and local data process capabilities.  Security: embedded computing systems need to access, store, manipulate, or communicate sensitive information and frequently need to operate in physically insecure environments.

Three types of reconfiguration :  Simple reconfiguration which utilizes the IEC model to avoid software coupling issues during reconfiguration.  Dynamic reconfiguration which utilizes techniques to properly synchronize software during reconfiguration.  Intelligent reconfiguration which exploits multi-agent techniques to allow the system to reconfigure automatically in response to change.

Comparison between conventional PLC systems and Real-time Distributed Control in reconfiguration  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.  On the other hand, in Real-time Distributed Control there is no need to be offline to edit the control software and we may commit the changes online, so there will be no instability in the running system.  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

Case study  Disadvantage of PLC :

Simple fault make a big disturbance - Most of Iran gas distribution stations establish many years ago. So control systems based on a PLC. In this system there is just one protocol for all the fire detectors in station’s site. When they send a pulse to central processor, without any delay all the station should be shot down. And all the gas which is stay in the stations pipes should vent to air. Then after solving the problem system run again - Sometimes fault cause by reflect of sun ray to one of fire detectors which is install in control room. - PLC have several disadvantages, same as centralize control which is limited us for agility condition possessing the fault in exact location and real time solution and non-reconfiguration in real time which means you should shot down the system then make yours changes.

- You can find the exact location of fire. - You can solve the disturbance in real time case - Control system make a smart unit so it can recognize when it should be shut down. In holonic manufacturing system

References  Design and implementation of a real-time holonic control system for manufacturing Xiaokun Zhang *, Sivaram Balasubramanian,Robert W. Brennan, Douglas H. Norrie Department of Mechanical and Manufacturing Engineering, University of Calgary,2500 University Drive, Calgary, AL, Canada T2N 1N4  Distributed real-time embedded systems: Recent advances, future trends and their impact on manufacturing plant control Carlos Eduardo Pereira *, Luigi Carro Electrical Engineering Department, Universidade Federal do Rio Grande do Sul (UFRGS), Brazil Received 15 December 2006; accepted 16 February 2007  Holonic Manufacturing Systems: Some Scenarios and Issues Martyn Fletcher Agent Oriented Software Ltd, Mill Lane, Cambridge, CB2 1RX, United  A Case Study on Migration from IEC PLC to IEC Function Block Control William Wenbin Dai, Valeriy Vyatkin, Department of Electrical and Computer Engineering University of Auckland, Auckland, New