Seminar: Multi-agent systems applied in manufacturing

Thu, 10/12/2009 - 11:00 - 12:00

Title: Multi-agent systems applied in manufacturing

Speaker: Marius Sutu

Abstract: Placed in a wide research context, namely the use of agents and agent oriented techniques in manufacturing, the thesis aimed first to explore the link between artificial intelligence (agents) and flexible manufacturing systems. Further investigation pointed to holonic manufacturing systems, as a new ground for agent applications, providing support for defining semi-heterarchic organizations. A holon is the fundamental part of a holonic system, and conceptually a holon is an entity that is a whole in its context but also a part of a bigger scale system in a wider context. The general model for a holonic system is a level-based enterprise organization scheme, where inclusion relations are established vertically between entities on different levels, and collaboration relations are established horizontally within same level. What holons bring into the picture is the auto-organization concept, allowing the system to reshape itself if a change of goals or a faulty device would require it, so the manufacturing environment is still able to deliver. The main proprieties of a holonic system that make this possible are the recursive structure and the holonic concatenation, allowing a higher level holon to be composed from several other holons forming a holarchy.

From the implementation point of view, the most used holonic system architecture is PROSA, which defines three basic types of holons from a functional point of view: the resource, the product and the order. What all these holons have in common is the software agent implementing the decisional part, and the communication interface to the executive part. As the holonic manufacturing system is inherently distributed regarding both the execution devices and their legacy control software, implementing the communication interfaces to link agents to them is the most challenging part. The communication mechanism based on these interfaces has to allow also the holonic concatenation, which implies a communication from one agent to a holarchy. Thus, a CORBA based distributed communication middleware is considered, which makes possible the use of a trader service to implement auction-based coordination systems (Contract .NET and its derivates). Also using the CORBA remote method invocations opens the road for the design of a service oriented architecture (SOA) for inter-level communication in the holonic system. The CORBA event service and using specific event channels allows state change and diagnosis information to be transparently delivered from a holon’s execution part to its control unit while preserving the SOA inherited loose coupling.

The last point of view regards increasing a manufacturing environment’s performance, which in the case of using holonic architectures will require specific techniques for evaluating a holonic manufacturing system, and inherently for evaluating the multi-agent system forming its decisional backend. One solution to achieve an evaluation and benchmark algorithm could be changing the viewpoint from the agents when observing the multi-agent system and look at them in a global action space. Narrowing action chains which lead to satisfying a goal would allow defining workflows and Petri-nets could be a solution in representing and analyzing them.

Seminario del Departamento
Edificio Ada Byron, María de Luna 1 Zaragoza