Development of a Large Autonomous Virtual Manufacturing System on Distributed Information Network

点击翻译按钮获取中文摘要

In this study, we investigate to develop a simulation-based decision support system under computer integrated manufacturing. The activities in the factory are modeled and expressed in a "virtual manufacturing system" (VMS) which is an internal model developed in a comput system. We focused to realize an autonomously distributed VMS as a distributed simulation system in this study in accord with the following considenration : the distributed information network will become an essential infrastructure in future factories, the distributed processing is effective to attain the high speed correspondence in large scale simulation, the distributed nature of the decision making activities in an organization can be well represented and modeled by a distributed autonomous decision processes on a distributed computer system and so on.The basic requirements for the manufacturing activity model are investigated and the basic specification of a VMS is defined. Simulation software packages in the mar … More ket are evalusted from the viewpoints of appropriateness in modeling the object simulation system of this study, especially in regard of the self-containment and/or additional extensibility of communication function to develop a distributed simulation system. In this respect, we investigated the communication and synchronization methods among elemental simulation systems, each representing a shop, transporation system, storage or distribution center in a factory. Based on the preliminary research on the established synchronization mechanisms reported in the past, we proposed a new mechanism named "Time Bucket Mechanism". Single-Phased and Double-Phased methods are also proposed to improve the simulation accuracy. Depending on the simulation speed and accuracy required, we can implement the most appropriate mechanism and parameters in the VMS.Based on the above studies, a prototype VMS is developed for a hypothetical factory. The experience in developing a VMS clarified overall problems to be solved in developing a large VMS and/or to improve the modeling capability in future. Various experiments by the developed VMS are made to evaluate the performance of proposed synchronization mechanisms on the simulation speed and accuracy, demonstrating the effectiveness of the mechanisms. Less