Jan Van Belle

A tabu search approach to the truck scheduling problem with multiple docks and time windows

While organizing the cross-docking operations, cross-dock managers are confronted with many decision problems. One of these problems is the truck scheduling problem. This paper presents a truck scheduling problem that is concerned with both inbound and outbound trucks at multiple dock doors. The objective is to minimize the total travel time and the total tardiness. The truck scheduling problem under study is described in detail and a mathematical model of the problem is provided which can be solved to optimality with a mixed integer programming solver, at the expense of a high computation time. Next, a tabu search approach is presented. Experimental results on new benchmark instances indicate that the proposed tabu search is able to find good quality results in a short time period, thus offering potential for integration in cross-docking decision support systems.

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.

An Approach for the Integration of a Scheduling System and a Multi-Agent Manufacturing Execution System. Towards a Collaborative Framework.

Abstract The paper presents advances in the development of a collaborative framework between a centralized scheduling system (SS) and a decentralized manufacturing execution system (MES). The SS is based on constraint programming (CP) technology, while the MES implements the PROSA reference architecture and applies the delegate multi-agent system pattern (D-MAS). The CP scheduling system generates a good quality global schedule, which in turn is executed by the MES. The framework is intended to develop capabilities to collaborate at runtime, exploiting the benefits of each specialized technology. Moreover, this work aims to show the impact on the execution process performance when an unexpected disruptive event occurs and turns the on-going schedule - as it was originally provided by the SS - into an infeasible one. The experimental results have shown a trade-off between efficiency and stability measures.

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.

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.

From Intelligent Agents to Intelligent Beings

This paper puts forward a novel concept: the intelligent being. Intelligent agents emphasize action and decision-making, which is strongly reflected in the results of agent research. However, real-world applications require much more than decision-making and the intelligent being addresses a crucial part of this: reflecting reality into the agent world. Importantly, reflecting some part of reality offers significant benefits for software developers. Indeed, properly designed intelligent beings inherit the coherency and consistency of the corresponding reality. This allows the development of systems with unprecedented complexity and size. This paper discusses the novel concept and its implications for software development. Importantly, the intelligent agents themselves may be considered as part of the corresponding reality, resulting in short-term forecasting services.

Incorporating trust in networked production systems

This paper presents a decision-making pattern that uses trust mechanisms. It comprises an expectation module that performs two functions. First, it infers—based on past performance—how information is to be understood (e.g. consider the expected outcome of a promise to deliver tomorrow, morgen, mañana or domani). Second, it infers—based on past performance—the uncertainty on the expected behavior. This pattern makes a key contribution by enabling cooperation in large systems of systems without requiring conventional integration, which typically results in rigidity and monolithic system designs. It contributes to the development of holonic systems or nearly decomposable systems that deliver most of the advantages of integration without the disadvantages.

Cooperation between a Holonic Logistics Execution System and a Vehicle Routing Scheduling System

The organization of the logistic operations in a cross-dock is complex. Cross-dock managers can be supported in this task by a logistics execution system (LES). A holonic LES uses a self-organizing and decentralized approach to control the cross-docking operations. Based on multi-agent technology, this approach aims to improve the robustness against disturbances. A drawback of this approach is however that this decentralized LES has no complete view on the system, in contrast to a centralized scheduling system. This paper presents the cooperation between a holonic LES and a vehicle routing scheduling system in order to combine the benefits of both systems. The holonic LES can benefit from the provided schedule to improve the global performance, while allowing the schedule to be executed, compensating for small deviations and possible simplifications. The results of some preliminary simulation experiments indicate that this cooperation can be realized and improves the global performance.

PROSA and delegate MAS in robotics

This paper discusses the application of the PROSA reference architecture [1] and its delegate multi-agent system coordination mechanism or D-MAS [2], [3] to robotic applications, particularly to the coordination of multiple mobile robots. Originally, PROSA and D-MAS have been developed for the manufacturing executions system or MES domain [4]. The application of PROSA to robotics is a generalization: PROSA has been elaborated but was never in need of modification. This reference architecture is applied to multiple application domains and differences are confined to its elaboration, specialization and instantiation. Likewise, the delegate MAS mechanism was reused across application domains. As a side effect, this facilitates the seamless integration of manufacturing execution systems and the coordination of mobile robots if they are PROSA and D-MAS implementations. This paper first presents the mapping of PROSA onto robotics. Next, it discusses how this technology from the MES domain enhances performance in mobile robot applications.