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PROSA, a reference architecture for holonic manufacturing systems. the key to support evolution and reconfiguration. dr. ir. Jo Wyns KULeuven / RealSoftware PMA KULeuven Jo.Wyns@advalvas.be http://www.mech.kuleuven.ac.be/~jwyns. Manufacturing control. logistical planning
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PROSA, a reference architecturefor holonic manufacturing systems the key to support evolution and reconfiguration dr. ir. Jo Wyns KULeuven / RealSoftware PMA KULeuven Jo.Wyns@advalvas.be http://www.mech.kuleuven.ac.be/~jwyns
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 Reference architecture System architecture Manufacturing control system style, types of components and interactions blueprint, components, interactions HW/SW, implementation What reduce development time, increase quality, unif. terminology abstraction, communication, indicate vital components execute Goal building style, construction elements, ... plans, sketches, specifications building Analogy
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
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
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
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
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
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)
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