Real-time software methodologies: Are they suitable for developing Manufacturing control software?

Computer-Integrated Manufacturing (CIM) systems may be classified as real-time systems. Hence, the applicability of methodologies that are developed for specifying, designing, implementing, testing, and evolving real-time software is investigated in this article.The paper highlights the activities of the software development process. Among these activities, a great emphasis is placed on automating the software requirements specification activity, and a set of formal models and languages for specifying these requirements is presented. Moreover, a synopsis of the real-time software methodologies that have been implemented by the academic and industrial communities is presented together with a critique of the strengths and weaknesses of these methodologies.The possible use of the real-time methodologies in developing the control software of efficient and dependable manufacturing systems is explored. In these systems, efficiency is achieved by increasing the level of concurrency of the operations of a plan, and by scheduling the execution of these operations with the intent of maximizing the utilization of the devices of their systems. On the other hand, dependability requires monitoring the operations of these systems. This monitoring activity facilitates the detection of faults that may occur when executing the scheduled operations of a plan, recovering from these faults, and, whenever feasible, resuming the original schedule of the system.The paper concludes that the set of surveyed methodologies may be used to develop the real-time control software of efficient and dependable manufacturing systems. However, an integrated approach to planning, scheduling, and monitoring the operations of these systems will significantly enhance their utility, and no such approach is supported by any of these methodologies.     

机器人制造陶瓷原型系统的研究

提出了采用工业机器人快速制造陶瓷熔射原型的方法。利用建立的数字化检测平台,测试机器人的点位置重复精度、直线轨迹位置精度和轨迹重复精度,找到其精度特性;建立NC代码与机器人代码的转换公式,得到了生成合适的机器人铣削路径代码的算法和CAM软件;根据机器人的精度特性和合适的加工路径,实际加工了用于熔射制模的陶瓷型熔射原型,验证了机器人制造系统的可行性。     

Crops: Implementation of a knowledge-based system to plan and monitor the production of a flexible line

CROPS (Coherent Rules for On-line Production Scheduling) is a general system aimed to plan and to control a flexible manufacturing system. The CROPS system receives production orders on a time-scale of one or two weeks from a medium-range planning (MRP) system. The planning and scheduling of those orders are made using a hierarchical temporal network that allows the easy use of rules which represent expert knowledge and common-sense reasoning. Furthermore, the hierarchical temporal network is flexible enough to take into account unavoidable perturbations occurring during plan execution without the need to replan all operations every time a perturbation occurs. Once the operations are planned, the control system transforms them into orders that are sent to the workshop (or to a simulator). With the help of rules, the control system monitors and diagnoses the execution of the orders using a model that maintains a continuous image of the workshop.     

基于语义的虚拟企业制造服务建模技术研究

为了实现协同制造环境下虚拟企业制造服务的自动发现、合成和执行,提出了一种基于语义的制造服务模型,从制造服务的资源构成视图、基本信息视图、功能视图、服务质量视图、访问视图和状态视图对制造服务进行了建模,并采用形式化语言对制造服务模型加以规范化的描述。在此基础上,采用扩展的Web服务本体描述语言对制造服务进行了建模实现。最后,基于网状中心城市区域网络化制造专业平台,开发了面向协同制造的虚拟企业制造服务管理原型系统,并验证了该原型系统的可行性。     

基于多Agent的分布式制造执行系统的建模

采用UML技术，提出了一种开放式、模块化、分布式、可配置、可集成和可维护的基于多Agent的制造执行系统(MES)模型。分析了制造系统中的制造执行系统域，提出了基于多Agent的MES模型并详细分析了该模型的MES的功能实现，最后给出了正在实施的MES系统框架。该MES系统能够容易地与企业资源计划(ERP)、车间控制系统(FCS)及其他制造系统相集成。     

Assessing the structural complexity of manufacturing systems configurations

Modern manufacturing systems are increasingly required to be flexible and adaptable to changing market demands, which adds to their structural and operational complexity. One of the major challenges at the early design stages is to select a manufacturing system configuration that both satisfies the production functional requirements and is easy to operate and manage. A new metric for assessing the structural complexity of manufacturing system configurations is presented in this paper. The proposed complexity metric incorporates the quantity of information using an entropy approach. It accounts for the complexity inherent in the various modules in the manufacturing system through the use of an index derived from a newly developed manufacturing systems classification code. The code captures the effect of various component types and technologies used in a manufacturing system on the system’s structural complexity. The presented metric would be helpful in selecting the least complex manufacturing system configuration that meets the requirements. An engine cylinder head production system is used to illustrate the application of the proposed methodology in comparing feasible but different manufacturing system configurations capable of producing the cylinder head based on their structurally inherent complexity.     

Multiple-Objective Scheduling for the Hierarchical Control of Flexible Manufacturing Systems

This paper presents a hierarchical approach to scheduling flexible manufacturing systems (FMSs) that pursues multiple performance objectives and considers the process flexibility of incorporating alternative process plans and resources for the required operations. The scheduling problem is solved at two levels: the shop level and the manufacturing system level. The shop level controller employs a combined priority index developed in this research to rank shop production orders in meeting multiple scheduling objectives. To overcome dimensional complexity and keep a low level of work-in-process inventory, the shop controller first selects up to three production orders with the highest ranking as candidates and generates all possible release sequences for them, with or without multitasking. These sequences are conveyed to the manufacturing system controller, who then performs detailed scheduling of the machines in the FMS using a fixed priority heuristic for routing parts of multiple types while considering alternative process plans and resources for the operations. The FMS controller provides feedback to the shop controller with a set of suggested detailed schedules and projected order completion times. On receiving these results, the shop controller further evaluates each candidate schedule using a multiple-objective function and selects the best schedule for execution. This allows multiple performance objectives of an FMS to be achieved by the integrated hierarchical scheduling approach.     

A distributed knowledge-based approach to flexible automation: The contract net framework

This article applied distributed artificial intelligence to the real-time planning and control of flexible manufacturing systems (FMS) consisting of asynchronous manufacturing cells. A knowledge-based approach is used to determine the course of action, resource sharing, and processor assignments. Within each cell there is an embedded automatic planning system that executes dynamic scheduling and supervises manufacturing operations. Because of the decentralized control, real-time task assignments are carried out by a negotiation process among cell hosts. The negotiation process is modeled by augmented Petri nets —the combination of production rules and Petri nets—and is excuted by a distributed, rule-based algorithm.     

机电系统的概率行为树建模及可靠性评价

直接利用模型检测工具提供的形式化语言对系统进行形式化建模直观性较差、建模难度大，因此利用概率行为树对机电系统进行形式化建模，并通过概率模型检测对机电系统进行可靠性评价。对机电系统功能执行过程中功能载体的状态及其变迁进行了研究。基于概率行为树的语义和句法，提出了机电系统状态变迁过程的概率行为树建模方法，开发了建模支持工具。利用该建模工具可实现机电系统的概率行为树建模并能将其转换为基于PRISM语言的形式化模型。基于机电系统的潜在故障，用连续随机逻辑对机电系统可靠性评价指标进行形式化规约。基于概率行为树模型和可靠性评价指标的形式化规约，利用模型检测工具PRISM实现了对机电系统的可靠性评价。该方法比直接使用形式化语言建模更直观、易于理解和掌握。     

A model management systems approach to manufacturing systems design

Manufacturing systems design involves the solution of a complex series of interrelated problems. This complexity will increase in the future as manufacturing practices change to meet increased global competition. Research within manufacturing systems design has mainly been focused on finding improved models for solving particular problems, or extending existing modeling techniques. This has resulted in numerous modeling tools being available to support manufacturing systems design. However, little research work has been carried out into consolidating the existing theories and models. As a result, a large body of this work has not been applied in industry.Model management has evolved as a research area which investigates methods for storing, modifying, and manipulating models. This article describes a prototype model management system for manufacturing systems design. The objective here is not to develop another decision support system for manufacturing design, but to illustrate, through the development of a prototype system, a number of key ideas of how concepts from the area of model management systems can be used to support manufacturing systems design. The prototype model management system utilizes the structured modeling framework and uses an extended version of the structured modeling language. An important aspect of the prototype model management system is the incorporation of the model development task, thus allowing the system to be easily updated and adapted. The prototype system was evaluated using a range of queueing network models for manufacturing systems design.     

RDCAPP: A real-time dynamic CAPP system for an FMS

Computer-aided process planning (CAPP) systems need to consider the uncertain nature of the shop-floor prior to the identification of job routes and processing sequences. This paper describes the design and development of a prototype, real-time dynamic CAPP (RDCAPP) system for a multimachining-centre flexible manufacturing system (FMS). Concepts relevant to this research include CAPP, profile input using group technology (GT), artificial-intelligence-based expert systems, and FMSs.RDCAPP considers facility characteristics, machine capacity and the current shop-floor conditions prior to developing a process plan Input to the system is through a GT code and additional auxiliary interactive inputs. RDCAPP uses uncertainty management techniques to keep track of and adapt to changes in shop-floor status. The paper discusses the architecture of RDCAPP in detail. The system was tested rigorously and its outputs validated. Ideas for future research are presented.     

利用Inventor二次开发研究拆卸约束自动生成方法

通过研究标准连接件对拆卸约束的影响,提出基于连接件知识的规则推理方法,并将其与现有的几何推理方法相集成,实现了对拆卸约束的自动生成。应用设计零件特征数据处理、零件接触约束生成、基于连接件知识推理的优先约束生成、基于几何推理优先约束的生成及拆卸约束图形处理五个主要系统模块,在Autodesk Inventor的二次开发平台上,应用VB.NET开发了产品拆卸约束自动生成的原型系统,并经实例验证,说明应用该系统自动生成拆卸约束是有效可行的。     

面向复杂产品的协同制造执行平台框架及运作流程研究

为了有效地提高面向复杂产品的车间协同制造执行能力,在分析当前研究应用现状的基础上,提出了一种面向复杂产品的协同制造执行平台框架。在此基础上对面向复杂产品的协同制造执行平台运作流程进行研究,并进行原型系统开发和应用。     

基于面向服务架构的企业间业务协同服务平台及技术研究

借鉴面向服务的架构、业务流程管理和语义Web服务等相关的标准和技术,讨论了面向服务架构的结构、服务类型划分、服务总线,然后利用现有的服务中间件,建立基于面向服务架构的企业间业务协同服务平台.平台采用基于面向服务架构的业务流程管理框架,分离核心业务逻辑和流程控制逻辑,采用面向语义的流程服务模型,构建Web服务的执行环境,以提高业务服务和流程服务的动态发现和建模能力,最后给出了原型.     

基于XML的自适应网络化制造资源管理系统

先进制造模式的应用以及先进制造技术的发展 ,特别是面向企业和产品的、设计与管理相结合的现代CAPP的提出 ,对制造资源的管理提出了更高的要求。本文结合企业级 CAPP系统 THWeb CAPP的研究和实践 ,借助自适应思想和 XML 理念 ,定义制造资源的 XML 应用— MRXML,进而建立自适应的制造资源数据结构模型及基于它的网络化制造资源管理系统原型 ,最后指出该系统的优缺点。     

智能重构制造控制系统集成框架

为提高制造控制系统的智能重构能力,扩展了IEC 61499基本功能块模型,提出了知识功能块新概念,并将其作为功能单元构建了智能重构制造控制系统集成框架.在阐述了智能重构与智能控制并行执行过程的基础上,提出了基于Web Services面向服务的制造控制系统软件体系结构,并采用统一化建模语言建模语言进行了系统设计.通过一个原型系统运行实例,验证了IEC 61499功能块标准、Web服务中间件和面向服务哲理在实现智能重构制造控制系统方面的有效性.     

面向数据流嵌入式系统的并发设计方法

嵌入式系统复杂度的不断提高和设计周期的不断缩短,需要更快速、有效的设计方法.基于动态数据流图模型技术和面向部件的实现结构,本文描述了一种适用于面向数据流领域嵌入式系统的并发设计方法,这种设计方法在保持一致性的前提下,将一个嵌入式系统的设计过程分解成一系列相互独立的设计项目,由此,使得设计工作可并发进行.此外,软硬件部件和数据通路实现代码框架的自动生成,不但能显著加速设计过程,而且确保了目标系统的可集成性.     

An Object-Oriented Approach to an Agile Manufacturing Control System Design

Modern manufacturing control systems must respond quickly to continuous change in an agile manufacturing environment. With traditional manufacturing control system programming, it is time-consuming to make changes as a result of separate databases for the programmable logic controller (PLC), man–machine interface (MMI), and supervisory control and data acquisition (SCADA) packages. To resolve this, an object-oriented model of the control system using the unified modelling language (UML) is proposed, which then provides control and diagnostic code, enabling the network architecture, data mapping and control and diagnostic system to be designed within a single tool. The model is defined in accordance with the virtual machine concept which decomposes the complex machine into smaller elements. Based on the virtual machine concept, the model consists of the conceptual (or normal perception for the system) and control view (the control perception of a control engineer). A case study demonstrates the concept with both control and diagnostic code consistently derived from a single model.     

AEOS生产制造体系的建设研究

本文以我国航空发动机自主研制为背景,对标国际航空发动机制造体系及标准,探索我国航空发动机AEOS生产制造体系的建设,围绕需求和管理目标,构建总体框架,建立生产制造体系,提高生产运营管理的规范性,实现基于流程和信息化管理方式转变,优化生产组织方式,强化生产保障能力,提高生产执行力,逐步实现生产运营的精益化转型。提升我国航空发动机零部件的制造能力,为我国航空发动机的快速发展奠定基础。