Paul Verstraete

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 robust and efficient planning execution

This paper presents a holonic manufacturing execution system (MES) that cooperates with a planning system. This cooperation allows to combine the robustness and flexibility of the holonic MES with the optimisation performed by the planning system. The paper investigates the effect on the global performance of this cooperation for a specific manufacturing case in a series of experiments. It compares the effect of this cooperation when the planning is optimal with regard to the manufacturing case with situations where the planning system is not optimal. More precisely, it compares the performance of the HEMS in situations where the planning systems systematically misestimates the execution time of a workstation (e.g. a poorly maintained workstation or a partially operational workstation) to situations where this is not the case. The experiments are conducted under varying work loads. Also, the effort the Holonic MES puts in finding new solutions resembling the planning is varied. Finally, the paper reports the results of the experiments and draws conclusions.

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.

Emergent forecasting using a stigmergy approach in manufacturing coordination and control

This paper presents the design of new manufacturing coordination and control systems based on multi-agent technology. This design aims to cope with a dynamic environment characteristic for manufacturing systems nowadays. One important feature to handle these dynamics is having the ability to plan ahead, thus avoiding problems before they occur. Therefore, one novel characteristic of the system is the ability to perform emergent forecasting. Regarding emergent forecasting, an important issue that rises from this design is how to ensure that the forecast is reliable, and on the other hand, that the system is still fast enough to react against disturbances. This paper elaborates on the agents that form the system, and proposes a way to engineer it. Moreover, this paper also describes emergent forecasting. In addition to that, the trade off between responsiveness and forecast reliability (system nervousness issue) is also discussed in this paper, altogether with an example on the design of social acceptable behaviour that aims to handle the nervousness issue. Finally, some implementation and prototyping results are presented.

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.

E Pluribus Unum: Polyagent and Delegate MAS Architectures

For the past few years, our research groups have independently been developing systems in which a multi-agent system (typically of lightweight agents) provides some functionality in service of a higher-level system, and often of a higher-level agent in that system. This paper compares our approaches to develop a more generic architecture of which our individual approaches are special cases. We summarize our existing systems, describe this architecture and the characteristics of problems for which it is attractive, and outline an agenda for further research in this area.

Real-world production scheduling for the food industry: An integrated approach

The present paper offers an integrated approach to real-world production scheduling for the food processing industries. A manufacturing execution system is very appropriate to monitor and control the activities on the shop floor. Therefore, a specialized scheduler, which is the focus of this paper, has been developed to run at the core of such a system. The scheduler builds on the very general Resource Constrained Project Scheduling Problem with Generalized Precedence Relations. Each local decision step (e.g. choosing a route in the plant layout) is modeled as a separate module interconnected in a feedback loop. The quality of the generated schedules will guide the overall search process to continuously improve the decisions at an intermediate level by using local search strategies. Besides optimization methods, data mining techniques are applied to historical data in order to feed the scheduling process with realistic background knowledge on key performance indicators, such as processing times, setup times, breakdowns, etc. The approach leads to substantial speed and quality improvements of the scheduling process compared to the manual practice common in production companies. Moreover, our modular approach allows for further extending or improving modules separately, without interfering with other modules.

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 Holonic Chain Conveyor Control System: An Application

The control of the flow of goods through an extensive chain conveyor system is a complex task. The currently used control system (based on dispatching rules) is robust but does not take advantage of all opportunities. An alternative approach makes use of a planning algorithm to determine the routing decisions. This requires however an ad hoc algorithm and regular maintenance. The paper examines how the concepts and principles of Holonic Manufacturing Execution Systems can be used to control the product flow. This holonic multi-agent approach makes the control system adaptive and reactive and requires less maintenance. To illustrate how disturbances are handled, the holonic approach is applied to a cross-dock distribution center equipped with chain conveyors.