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

在本研究中，我们探讨了计算机集成制造下基于仿真的决策支持系统的开发。虚拟制造系统（VMS）是在计算机系统中开发的一个内部模型。在本研究中，我们重点实现自主分布式VMS作为分布式仿真系统，主要考虑如下几点：分布式信息网络将成为未来工厂必不可少的基础设施，分布式处理可以有效地实现大规模仿真中的高速通信，分布式计算机系统上的分布式自治决策过程可以很好地表示和建模组织中决策活动的分布式性质等。研究了制造活动模型的基本要求，定义了制造活动模型的基本规范。从建模本研究对象仿真系统的适宜性角度，特别是考虑到开发分布式仿真系统所需的自包容和/或通信功能的额外可扩展性，对市场上的仿真软件包进行了评价。在这方面，我们研究了元素模拟系统之间的通信和同步方法，每个模拟系统代表工厂中的商店、运输系统、存储或配送中心。在对已有的同步机制进行初步研究的基础上，提出了一种新的同步机制——“时间桶机制”。为了提高仿真精度，还提出了单相法和双相法。根据所需的仿真速度和精度，我们可以在VMS中实现最合适的机制和参数。在上述研究的基础上，针对一个假想的工厂开发了一个原型VMS。开发VMS的经验阐明了在开发大型VMS和/或在将来提高建模能力时需要解决的总体问题。在开发的VMS上进行了各种实验，以评估所提出的同步机制在仿真速度和精度方面的性能，证明了该机制的有效性。少

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