PROSA, a reference architecturefor holonic manufacturing systems

dr. ir. Jo Wyns KULeuven / RealSoftware

PMA KULeuven

Jo.Wyns@advalvas.be

http://www.mech.kuleuven.ac.be/~jwyns

the key to support evolution and reconfiguration

Manufacturing control

• logistical planning

• technological planning, late design decisions

• resource allocation

• downloading of NC-programs

• tracking of materials, tools, people, ...

• etc.

=> but broad in space and time

Problem statement

• Disturbances– machine break-down

– rush order

– missing tools

– missing materials

– absenteism

– etc.

• On-line manufacturing control algorithm

• Changes– new technology

– new markets

– new products

– new organisational structures

– etc.

• Manufacturing control system architecture

Reference architecture

Manufacturingcontrol system

System architecture

Referencearchitecture

HW/SW,implementation

blueprint,components,interactions

style, types of components andinteractions

executeabstraction, communication, indicate vital components

reduce development time, increase quality,unif. terminology

buildingplans, sketches, specifications

building style, constructionelements, ...

Wha

tG

oal

Ana

logy

Hierarchical control (ex.)

Heterarchical control (ex.)

Hierarchical vs. heterarchical control

• Every child node has only 1 parent.

• Master - Slave

• Low Adaptability

• Low support for Evolution

• => for large systems

• => not for dynamic systems(changes/disturbances)

• Distributed

• No supervisory control

• Negociation

• No global optimisation

• => for homogeneous systems

• => not for large systems

Holonic manufacturing systems (HMS)

Manufacturing holon

Holon• whole, autonomy• part, co-operation

Stability• decoupling• self-similar

PROSA: basic holons

Basic holons

Holonic Manufacturing System

Order holon

0..*

0..*

Product holon

0..*

1..*

10..*

Resource holon

0..*

1..*1..*

0..*

1..*

0..*

0..*

0..*

0..*

1..*

0..*

1..*

Process knowledgeProcess execution knowledge

Production knowledge

1..*

0..*

10..*

1..*

0..*

Aggregation

• hiding details in aggregated structures

• open-ended at top and bottom

• multiple aggregations (not tree-shaped)

• not static, may change dynamically

• resource, product, order aggregations

Aggregation

Resource holon

0..*0..* 0..*0..* 0..*0..*Equipment holon Shop holon

0..*0..*

Workstation holon0..*0..* 0..*0..* Factory holon

0..*0..*

0..*0..*

0..*0..*

0..*0..*

0..*0..*

0..*0..*

Specialisation

• Different types of resources: – Processing resources, workstations, – Transport resources, transport system– ...

• Different types of orders and products:– Stock orders, customer orders– Different product families

Specialisation

Resource holon

Shop holon Workstation holonEquipment holon

Assembly shop Milling shop

CMM station Milling station Assembly station

Robot NC-machine Conveyor

Staff holons

• Basic holons + aggregation + specialisation– only heterarchical control

(aggregation contains no control functionality)– distributed system

• But ...– centralised problem solving is sometimes easier

(e.g. scheduling)– hierarchical structures in factories

Staff holons

• Expert gives advise to the basic holons

• Holonisch manufacturing system– distributed system:

robust and adaptable– ability for centralised functions

• Behaviour: hierarchical, heterarchical, and mengvormen zijn mogelijk

Staff holons (3)

0..*

1..*

announce work-to-do

0..*

Order holon

provide order schedule

0..1

announce capacity

0..*

Resource holon

0..*

1..*

Process execution knowledge

provide resource schedule

0..1

Scheduler holon

0..*

0..1

0..*

0..1

Flexible assembly system

• Apply PROSA to real machines (robots & PLC)

• Switch between real machines and simulation (virtual factory)

• Logistical decisions– replaceable dynamic market mechanism– reactive centralised scheduler and

schedule execution

Flexible assembly system

Example

Horizontal self-similarity

• Specialisation uses inheritance (OO)

• All kind of resource holons share common interface and behaviour; idem for order holons and product holons

• => Special cases/types can be handles similar to nominal ones

• e.g. rush order; first-of order; high volume vs. high quality product;

Vertical self-similarity

• Holarchy is a resource holon on itself;resource holon can internally be a holarchy

• Homogeneity in internal functioning of holarchies

• Resource holon is independent of holarchy to which it belongs

• e.g. belong to multiple holarchies at the same time (human)

Self-similarity (3)

0..*0..*

0..*0..*

0..*

0..*

Order holon

0..*0..*

0..*0..*

0..*

Resource holon

0..*0..*

0..*

0..* 1..*

Product holon

0..*0..*

0..*

1..*

Conclusion

• PROSA: Product-Resource-Order-Staff Architecture– necessary basic holons– optional staff holons – generalisation of hierarchical and

heterarchical architectures– software framework

Conclusion

• Evolution & reconfiguration– decoupling of control algorithm from system

architecture– decoupling of logistical and technological

aspects– self-similarity

More details on PROSA

• Van Brussel, H., J. Wyns, P. Valckenaers, L. Bongaerts, P. Peeters, (1998) Reference Architecture for Holonic Manufacturing Systems: PROSA, Computers In Industry, Special Issue on Intelligent Manufacturing Systems, Vol. 37, No. 3, pp. 255 – 276.

• Wyns, J. (1999), Reference architecture for holonic manufacturing systems - The key to support evolution and reconfiguration, Ph.D. thesis, ISBN 90-5682-164-4, K.U.Leuven.

• http://www.mech.kuleuven.ac.be/pma/research/hms

• http://www.mech.kuleuven.ac.be/~jwyns

Integration with scheduling

• Planning = advise: – what, when, how?– not: invent standard for planning advise– but: design pattern for integration

• Solution: multiple decision taking algorithms + one selection algorithm in order holons

Integration with scheduling

theOrder : Order

theRAAlgorithm : RAAlgorithmtheRASelectionAlgorithm :

RASelectionAlgorithm

selectedRATask suggestedRATask3: getSuggestion(possibleResource[])

4: select(suggestedRATask[])

aScheduler : Staff systemConfigurator : Staff

1: setRASelectionAlgorithm(RASelectionAlgorithm)

2: addRAAlgorithm(RAAlgorithm)

Man-machine interface