多重入生产线的CONWIP投放方法研究

CONWIP（Constant Work in Process）是一种基于拉式（pull）控制物料投放的方法。最初应用于Flow Shop式生产系统,通过限制半成品数量以控制生产线运作提供可靠的制造周期。然而,原始的CONWIP方法不能适应半导体这类同一加工站多重人的生产系统。该文根据半导体生产线多重人的特性,提出与多重人瓶颈相结合的CONWIP投放方法,不仅控制生产线中的半成品数量,并且结合了TOC（Theory of Constraints）思想,从而提高生产线的性能。最后,通过一些仿真证明了方法的有效性。     

串行饱和生产线模糊控制方法的研究

生产存储控制的任务是按时完成生产计划的前提下,控制生产节奏,尽量降低不必要的库存.为了在保持生产线最大通过率的前提下,达到平均在制品量最少的目的,采用模糊控制技术,对串行饱和生产线进行物料准入控制.在对物料准入控制问题进行简单描述的基础上,详细介绍了模糊控制器的设计.通过实例仿真与CONWIP控制进行了对比,结果表明采用模糊控制可以取得令人满意的效果.     

FMS的实时调度与控制方法研究

本文以 CIMS 中的基本单元 FMS 为对象,从离散事件动态系统角度出发,研究了 FMS 的实时调度与控制.首先,从递阶控制角度出发讨论了 FMS 的调度与控制,把一般的 FMS 的调度与控制系统划分成三层:调度层、事件轨迹控制层和单元逻辑控制层,提出了 FMS 调度与控制的一体化结构——调度驱动监控结构.在此基础上,建立了 FMS 基于 Petri 网的调度驱动监控的形式化理论.     

基于Petri网的柔性制造系统作业调度研究与实现

选择面向对象的有色Petri网对FMS进行建模,研究FMS调度控制问题.本文针对柔性制造系统的特点,采用面向对象的着色Petri网建立了由工件、机床、运送和仓贮对象等组成的模型.模型是一个包括加工系统、物流系统、管理系统在内的一个完整的FMS模型.该模型由于采用了面向对象技术,具有可移植性、可扩展性的特点,并且易于用软件去实现,本文使用"映射"法,把库所映射为软件数据、变迁映射为程序函数和方法、子系统映射为软件系统基本类,从而把FMS Petri网模型转化为FMS控制管理软件程序.本文采用简易的工艺文件数据,对FMS控制管理软件运行进行了测试.通过对测试结果的分析,验证了本文所建立的FMS物流系统模型和设计的FMS柔性生产线控制管理软件的正确性和有效性.     

供应链存储系统无线射频识别使能的定量在制品法控制策略仿真

无线射频识别(radio frequency identification,RFID)技术的出现为库存控制策略的创新提供了一条有效的途径.本文利用RFID技术,将原有单个制造系统的流通卡系统推广到供应链的多级库存网络中,设计了RFID使能的电子流通卡系统.基于电子流通卡,实现了RFID使能的定量在制品法(constant work-in-process,CONWIP)控制策略;并建立了CONWIP控制策略的分销网络模型.为比较和验证CONWIP控制策略性能,开发了三级分销网络仿真系统,使用该系统,将其与RFID使能的(r,Q)策略进行比较,验证了CONWIP策略在一定条件下,能够有效降低存储成本、提高服务水平.     

PROFIBUS在数控车间FMS控制中的应用

群控（DNC）是柔性制造系统（FMS）控制的一个重要组成部分,本文介绍了基于Profibus现场总线网的数控车间FMS控制系统的组成原理,信息模型,实现方法。DNC实施方案,给出了该系统的结构与特点,较详细地说明了MIS软件功能。该方案适合各种FMS系统中的DNC控制,并有利于FMS系统的扩展。     

PROFIBUS在数控车间FMS控制中的应用

群控(DNC)是柔性制造系统(FMS)控制的一个重要组成部分．本文介绍了基于Profibus现场总线网的数控车间FMS控制系统的组成原理，信息模型，实现方法。DNC实施方案，给出了该系统的结构与特点，较洋细地说明了MIS软件功能。该方案适合各种FMS系统中的DNC控制。并有利于FMS系统的扩展。     

一种改进型遗传算法在FMS刀具调度中的应用

在柔性制造系统（FMS）中,刀具调度问题关系着刀具的利用率和整个FMS的生产效率,如何对众多刀具进行合理的调度已成为当前FMS中的一项关键技术。在对遗传算法进行改进的基础上建立了在有限刀具资源约束下的FMS刀具调度优化模型,得出针对刀具交换次数的目标函数,通过比较与实验验证了这种算法的有效性和优越性。     

基于ARINC429和TCP/IP的FMS仿真通信平台设计与实现

针对目前飞行管理系统(FMS)仿真通信通用性和重构性差的问题,研究了采用ARINCA29总线结合TCP/IP协议构建FMS仿真通信平台的方法,通过定义FMS仿真概念模型并设计数据结构、数据交互函数和平台控制界面,给出了一种满足FMS仿真要求的通信平台的实现方法,最后对通信平台进行性能测试,验证了平台具备可靠性和实时性....     

基于EHLEP-N模型的FMS实时调度和控制

本文提出一种新的更适合柔性制造系统(FMS)建模的扩展高级E-Net,简称EHLEP-N (Extended High Level Evaluation Petri Net).将EHLEP-N与专家系统技术相结合,使 EHLEP-N对FMS更具有描述性,推理和决策能力.以EHLEP-N为FMS的建模工具,设 计并建立FMS实时调度控制专家系统.借助于该系统,提出并研究新的旨在减少空闲(noinputs) 和消除阻塞的实时动态再调度规则.加工实验结果表明:1)该系统满足实时性和调 度控制功能的要求;2)新规则的产率(throughputs)比传统规则平均提高7％.     

A CONWIP model for FMS control

Production inventory control is one of the most important aspects of a flexible manufacturing system (FMS) design. CONstant Work In Process (CONWIP), which is a hybrid of push-and-pull type systems, offers an alternative to effective utilization of the expensive FMS equipment while still meeting customer requirements. In the selection of an FMS control method, material handling often becomes one of the capacity constraints which forms the basis of various research interests. In this paper, a structure-based model for a CONWIP-controlled FMS is proposed, and within it, the node type characteristics concept is used to describe the constraints in FMS. Furthermore, simulation is used to determine the card number based on the structure-based model. The simulation results demonstrate that the model is suitable for the design and operation of FMS. The model can be used as a manufacturing execution system of enterprise resources planning. An architecture for this integrated design based on Internet/Intranet systems is also proposed.     

A performance comparison between Kanban and CONWIP controlled assembly systems

There exists controversy on the superiority of logistics control systems. Kanban and CONWIP systems are focused on and analyzed in this paper. CONWIP is a well-known production control system, and some papers have shown it has better performance than the Kanban system. Our research shows that the Kanban is more flexible for the assembly system under concern with respect to a given objective than the CONWIP. In some cases, if the number of kanbans at each manufacturing/assembling station is optimally set, Kanban system outperforms CONWIP with a lower average WIP and the same level of throughput. That is, the distribution of kanbans can be an important design parameter of the system. We also propose two different policies to release cards in a CONWIP controlled assembly system, followed by their comparison results.     

Developing a framework for performance analysis of a production process controlled by Kanban and CONWIP

In this paper, we develop a framework for comparing pull production control systems, which defines and contains of activity interaction diagram and critical circuit. Kanban and CONWIP control systems are focused on and analyzed. We show that, for a production process controlled by Kanban or CONWIP, the critical circuit determines performance measures, such as the system throughput. Initial inventories as well as card distribution are important parameters that decide the critical circuit, and hence influence the system performance. In addition, by means of our proposed framework, we provide comparative results between Kanban and CONWIP control systems in tree-shaped production processes and serial production lines as sample applications of the framework. The results show that determining the certain superior production control system depends on the system parameters, such as the process structure, initial values and processing times.     

CONWIP based control of a lamp assembly production line

Efficient and effective production control systems are very important for manufacturing plants. CONWIP, one of these production control systems, has a high potential of becoming the best one available because it suits a variety of production environments and is easy to implement. In the following paper, we compare the single-loop and multi-loop CONWIP production control systems for an actual lamp assembly production line producing different kinds of products with discrete distribution processing time and demand. A model is formulated with respect to total cost and service level. A novel rule-based genetic algorithm (GA) approach is proposed for the multi-loop CONWIP system to find the optimum parameter setting. The results have shown that the single-loop CONWIP production control system is more efficient than the multi-loop system. It can greatly decrease the total cost and the WIP (Work-In-Process) with zero shortage probability.     

An object-oriented model for FMS control

The flexible manufacturing system (FMS) is a distributed network of heterogeneous programmable manufacturing machinery, such as assembly lines and numerically controlled machines. Despite these interconnected, programmable hardware elements, the success of building a truly flexible manufacturing system has been limited so far, owing to the lack of flexibility in its control software layer. In integrating heterogeneous machinery, many existing FMS control software systems depend structurally on specific machinery and job-scheduling strategies, and thus it is difficult to incorporate new developments in FMS organization and operational requirements. In searching for an open architecture for the FMS control software system, this paper presents an object-oriented FMS data model. Among others, it represents each physical cluster of related machinery (called a flexible manufacturing cell) as an object. To facilitate the integration of heterogeneous physical cells, such cell objects share a common protocol of interacting with the main control process through inheritance from the abstract cell class. Other related physical and abstract entities in FMS are also modelled as objects, with their similarity and difference captured in inheritance hierarchies. To verify the proposed approach experimentally, a prototype FMS control software system named FREE (FMS Runtime Executive Environment) has been implemented on top of a commercial object-oriented database system.     

基于遗传算法和排队网的串联CONWIP系统流通卡数的确定方法

在CONWIP(constant work in process)系统中,流通卡数是系统有效运行的关键因 素.文中针对串联CONWIP系统,提出了非线性整数规划模型和排队网模型相结合的问题描述 模型,以及遗传算法与排队网络分析相结合的问题求解算法.实例仿真验证了该方法的有效性.     

An Iterative Synthesis Approach to Petri Net-Based Deadlock Prevention Policy for Flexible Manufacturing Systems

This paper proposes an iterative synthesis approach to Petri net (PN)-based deadlock prevention policy for flexible manufacturing systems (FMS). Given the PN model (PNM) of an FMS prone to deadlock, the goal is to synthesize a live controlled PNM. Its use for FMS control guarantees its deadlock-free operation and high performance in terms of resource utilization and system throughput. The proposed method is an iterative approach. At each iteration, a first-met bad marking is singled out from the reachability graph of a given PNM. The objective is to prevent this marking from being reached via a place invariant of the PN. A well-established invariant-based control method is used to derive a control place. This process is carried out until the net model becomes live. The proposed method is generally applicable, easy to use, effective, and straightforward although its off-line computation is of exponential complexity. Two FMS are used to show its effectiveness and applicability     

多阶段CONWIP 系统流通卡分布的确定方法

在ＣＯＮＷＩＰ系统中,流通卡分布是系统有效运行的关键因素。针对多阶段ＣＯＮＷＩＰ系统,提出了基于遗传算法和仿真的流通卡分布的确定方法。研究实例表明,基于遗传算法获得的结果是合理的,并且节约了计算时间。