Bart Saint Germain

On the design of emergent systems: an investigation of integration and interoperability issues

Abstract Many useful manmade systems in this world are extremely complex; a typical example is a large infrastructure. No design team ever invents these artifacts because they are too complex. These artifacts are made by combining existing elements (legacy) and by building new subsystems without explicit and comprehensive up-front coordination. To a large extent, these complex systems emerge and evolve. Experience shows that designers frequently fail to develop artifacts that, when combined, facilitate the emergence of effective and efficient systems. This paper formally elaborates the mechanism behind this phenomenon, and proposes principles for the design of components for emergent systems. The above insights were gained during the development of research prototypes for multi-agent manufacturing control; manufacturing systems are notorious for experiencing integration and interoperability problems as described above. Consequently, the design principles are discussed and illustrated on the design of multi-agent manufacturing control systems but also on work by others. Finally, although this paper mainly discusses the above in a generic fashion, and although the generic statements hold in an application-independent manner, it is important to appreciate that the applicability of the above insights and principles has significant limitations, which are discussed in the paper.

Self-organising in multi-agent coordination and control using stigmergy

In order to cope with todays dynamic environment, the described manufacturing control system is designed as a self-organising multi-agent system. The design of this novel system implements the PROSA reference architecture [1]. Coordination among agents is done indirectly through a pheromone-based dissipative field as is done by social insects in coordinating their behaviour. In this case, our agents act as social insects interpreting the pheromones put by the others in the environment. This control system is built from the basic elements of any manufacturing controller, namely products, resources and orders. However, the overall control system is constructed not only from those basic elements but also employing the appropriate interaction patterns among the agents who represent them. For coordination purposes, the agents send out a kind of mobile agents - artificial ants - to lay down information on the environment. In our case, where fulfilling the manufacturing orders is the main concern, there are at least 3 types of ant in this system: (1) feasibility ants - to propagate information concerning the feasible finishing routes; (2) exploring ants - to explore the feasible routes; and (3) intention ants - to propagate the route preferences. The overall mechanism enables the system to exhibit a self-organising behaviour.

Emergent short-term forecasting through ant colony engineering in coordination and control systems

Abstract This manuscript presents a design for the emergent generation of short-term forecasts in multi-agent coordination and control systems. Food foraging behavior in ant colonies constitutes the main inspiration for the design. A key advantage is the limited exposure of the software agents in the coordination and control system. Each agent corresponds to a counterpart in the underlying system and can be developed and maintained exclusively based on knowledge about its counterpart. This approach to make non-local information available without exposing the software agents beyond their local scope is the research contribution and focus of the discussion in this paper. The research team applies this design to multi-agent manufacturing control systems and to supply network coordination systems, but its intrinsic applicability is broader.

Towards the design of autonomic nervousness handling in holonic manufacturing execution systems

Manufacturing control systems that are built along the holonic manufacturing execution systems (HMES) approach, are able to generate short-term forecasts (resource loads and order routings). However, the reliability of these forecasts has to be balanced against the reactivity of the system in coping with the changes and disturbances that happen in the manufacturing environment. These phenomena are captured in so-called system nervousness issues. This paper discusses the system nervousness issues and how to handle them.

MAS coordination and control based on stigmergy

This paper discusses a multi-agent coordination and control system. The system implements the PROSA architecture [12] and uses a specialized approach to stigmergy. This approach is discussed in relation to more commonplace designs based, for instance, on negotiation protocols. Next, the discussion focuses on the commonalities and differences between the source of inspiration for the system design - food foraging in ant colonies - and the resulting coordination control system itself. In particular, the discussion reveals that the multi-agent coordination and control system is based on deeper insights rather than a superficial translation of the biological example.

A benchmarking service for the manufacturing control research community

This paper presents the development—by the IMS Network of Excellence (cf. http://www. ims-noe.org)—of a web-based benchmarking service for manufacturing control systems. The paper first discusses the rationale behind this development. Next, the architecture and usage of the benchmarking service is presented and illustrated. Finally, the paper addresses the current status of the benchmarking service.

Multi-Agent Manufacturing Control: An Industrial Case Study

Abstract The paper discusses the development of a multi-agent manufacturing control system for an industrial application. This multi-agent system follows the PROSA reference architecture and applies ail ant colony design (stigmergy) to provide coordination and emergent forecasting services. The paper first presents the experimental set-up: • The properties of this shop and its particular challenges to control systems • The emulation of an existing production shop in industry • The multi-agent system connected to this emulation Next, the paper discusses the real-time aspect of the emulation. Third, the multiagent control system is presented. Filially, the paper discusses the browser to analyze the results generated during simulation runs

A Collaborative Framework between a Scheduling System and a Holonic Manufacturing Execution System

This paper presents developments on a collaborative framework between a centralized manufacturing scheduling system (SS) and a decentralized manufacturing execution system (MES). The paper intends to integrate such systems with the aim of reducing the existing gap between detailed manufacturing scheduling systems and lower level systems, like MESs. Moreover, the framework exploits the benefits of each specialized technology and complements their capabilities in order to collaborate at runtime. The SS is based on constraint programming (CP) technology, while the holonic MES or HMES implements the PROSA reference architecture and applies the delegate multi-agent system pattern (D-MAS). The scheduling system generates a good quality schedule, which execution is performed by the HMES. In turn, the HMES requires services from the SS in order to update the schedule. The paper also shows the impact that disruptive events have on the execution performance. Experimental results have shown a trade-off between efficiency and stability metrics.

A Service-Oriented Approach for Holonic Manufacturing Control and Beyond

The Holonic Manufacturing Execution System (HMES), developed at K.U.Leuven, utilizes a service-oriented approach to control manufacturing operations in real time. This chapter first explains how manufacturing control emerges from interaction between intelligent products and intelligent resources. Services play a key role in this interaction and form a decoupling point between the generic control system and application-specific elements. To illustrate that this service-oriented approach allows applying the same concepts and principles to various domains, several applications in manufacturing, open-air engineering, robotics and logistics are described. Finally, the chapter describes how supporting services, such as maintenance, can be seamlessly integrated with the core activities of the system.

Intelligent Products in the Supply Chain Are Merging Logistic and Manufacturing Operations

Abstract The control of a supply chain becomes more and more complex. The actions and operations of the different parties need to be coordinated in order to control the supply chain in an efficient way. The concept of ‘Intelligent Product’ can play an important role in this challenge. The intelligent product searches actively for the needed services offered by (intelligent) resources. The Holonic Manufacturing Execution System developed at K.U.Leuven makes use of this concept to control the internal logistics of a manufacturing system. Because of the active role of the intelligent products, the HMES is scalable and can coordinate beyond organizational boundaries. The paper explains the intelligent product concept and indicates the advantages of this approach by describing how a cross-dock can be controlled and integration with the inbound and outbound vehicles can be achieved.