Conference Paper

Simulation assisted match-up rescheduling of flexible production systems subject to execution exceptions

DOI: 10.1145/1351542.1351866 Conference: Proceedings of the Winter Simulation Conference, WSC 2007, Washington, DC, USA, December 9-12, 2007
Source: DBLP


An immense amount of research work has been done in the areas of scheduling and re-scheduling of various types of manufacturing systems. In this paper we present a simula- tion assisted approach to rescheduling complex production system configurations subject to execution exceptions. Is- sues like how to bring the deviation of a schedule due to exceptions back to its original trajectory and how to do this in real-time without affecting co-ordination problems on the shop floor are addressed. Our results show that combin- ing simulation and optimization for rescheduling indeed helps to achieve both these objectives and that this ap- proach proves to be promising to help reduce chaos in to- day's dynamic manufacturing environments.

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Available from: Wilhelm Dangelmaier
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    • "Besides, global competitors keep competing for introducing new products which effects on shortening the product life cycle. The implications of this situation are the diversity of environments within which the production planning and control system must operate have increased and will continue to do so [1]. In other word the scheduling become more sophisticated and even worst the planned production schedules often become ineffective in actual execution on the shop floor due to barely foreseen disturbance. "
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    ABSTRACT: Increased demand for customised products, sophisticated scheduling requirements caused by shorter product life cycle and hardly foreseeable disturbances have created a new challenge for the manufacturing industry. Planned production schedules often become ineffective in actual execution on the shop floor. If forecasts become less and less accurate, support for continuous changes is helpful. Given the high degree of automation in manufacturing systems, automatic control systems have become central to shop floors’ responsiveness. However, their state-of-the-art architectures are unable to cope with the challenge successfully. Improvements in information and communication technology makes the integration of simulation and control system more promising. The paper proposes an approach for supporting changes of routing strategy in an automated material flow system by utilising the integration. The approach includes (re-)planning of the automated material flow system, commissioning its logic control and controlling the material flow.
    Full-text · Article · Dec 2013
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    ABSTRACT: In a rapidly changing environment, good coordination of production and logistics at an operational level is required to handle rapidly evolving technology, frequently changing customer demand and satisfaction, and remain competitive. The job shop scheduling and the material flow control are two important factors influencing productivity and cost-controlling activities in any manufacturing system. The job shop scheduling is known as a non-deterministic polynomial-time hard problem itself, without considering the transportation or material flow of the system. Finding optimal solutions, however, requires an enormous computational effort, which becomes critical for large problems, particularly in situations where frequent changes in the environment occur. The material flow control system has to ensure the schedule has been met. But the planned production schedules often become ineffective when being executed on the shop floor. Given the high degree of automation in material flow systems, automated control systems have to support continuous changes. Although these two problems are strongly connected and solving one significantly impacts the performance of the other, so far these problems are solved independently. The complexity of the scheduling problem is increased when the material flow control is involved since not only a proper schedule must be created but an appropriate material flow needs to be provided. Due to this challenge, this dissertation has been designed to bridge the gap by initiating an approach for integrating predictive-reactive job shop scheduling with Programmable Logics Controlled (PLC) material flow. The objective is to develop an integrated control system that supports changes of routing strategy and schedule due to unexpected events. Features offered by state of the art material flow simulation software such as Open Platform Communications (OPC) interfaces and genetic algorithms have given the opportunity to realise this approach. By utilising the material flow simulation software, the integrated control system, which consists of a system model, a control model and a schedule generator, has been developed and realised. Through combinations of these system components, the OPC connection with the physical system enables the integrated control system to be used for generating schedules, analysing the physical system through simulation and controlling the material flow system. The concept can be applied for planning and operational purposes. As verification and validation, a demonstration prototype of integrated control system has been developed and applied in an industrial environment. The exemplary implementations prove not only that the planning and operation of material flow system is systematic, but it provides better outcomes, and significantly rescheduling and reconfiguration of the integrated control system can be performed with minimal effort.
    Full-text · Thesis · Sep 2013