Fundamental technology for RFID-based supervisory control of shop floor production system

To improve the leanness of shop floor production system, supervisory control of its production process should be accurate enough so that the state of every product can be tracked in time and its operation can be scheduled correctly. For this purpose, radio frequency identification (RFID) technology can be used to acquire accurate production data. This paper reports our research on the fundamental technology for RFID-based supervisory control of shop floor production system, in which production state data are acquired by RFID tags and readers, data communication is realized by programmable logic controller and industrial field bus technology, production process control is implemented by the host computer and material handling devices, and the supervisory control software is developed based on multithread technology. The details of these fundamental technologies have not been reported in existing literatures. A prototype of RFID-based supervisory control system is developed for an experimental manufacturing cell, and some experiments were done to verify the feasibility of these technologies.     

A Cascading Auction Protocol as a Framework for Integrating Process Planning and Heterarchical Shop Floor Control

A new contract net-style auction protocol is proposed as a framework for integrating process planning and shop floor control in heterarchical manufacturing systems. Process planning is partitioned into on-line and off-line activities; off-line process planning decisions are represented in a graph format and used as input for on-line process planning activities performed by machine controllers. Triggered by the opening round of an auction, the final on-line stages of process planning are dovetailed with the resource allocation process in the shop floor control system. The auction process allows final process planning decisions to be based on timely information, relying on the distribution of static process planning information rather than the distribution of a model of dynamic shop floor status and allowing a controller to identify all the primary and secondary resources and operations that must be provided for the incremental processing of a part.     

敏捷化车间制造执行系统研究

车间生产管理及运行的敏捷化是实施CIMS及敏捷制造战略的重要环节。制造执行系统（MES）是实现车间生产敏捷化的基本途径，MES的敏捷性体现为其性能上的快速响应和结构上的快速重组。采用MAS理论与方法研究MES的体系结构，并设计了Agent的统一结构形式以及各Agent之间的协作机制；开发了一个基于MAS的敏捷化MES原型系统，并阐述了其工作流程。     

Applying an Integrated Analysis Method to Develop a Shop Floor Control System

The fundamental concept of computer integrated manufacturing is to integrate the information flow, material flow and control flow of the whole manufacturing enterprise. One major task, which might be required during the integration process, is to model the related enterprise activities. Currently, the most common method of modelling automatic manufacturing systems is to describe the system from organisational, functional, information or process points of view. Many tools or methods have been developed to support those modelling processes. However, most of those methodologies are focused only on one viewpoint. There is very little connection among various viewpoints. Therefore, gaps might exist among those models which may need extra work to bridge them while implementing the developed model. In this research, an ARIS^™ based framework to assist shop floor controller development is proposed. The major merit of using ARIS is that an integrated model containing the organisation, function, information and process entities of the shop floor can be achieved. In addition, a set of rules was developed to transfer the logic of this integrated model to the control codes of the controller during the implementation stage. The main objective of this framework is to reduce the gaps among various models and hence to shorten the system modelling and development time.     

离散制造企业EAI架构

通过对IT系统在离散制造企业中应用情况的分析，构建了离散制造企业信息集成系统模型，以此为基础规划了一种企业应用集成（EAI）架构。该架构应用XML Schema为离散制造企业建立了一种信息元数据描述模型，以保证信息集成系统中数据的唯一性、一致性和准确性；通过引入扩展的高级事务模型并结合消息机制解决了企业长制造周期与业务过程管理的矛盾，提高了企业业务处理的速度和可靠性。以一个实例描述了该架构的实现过程。     

Advanced RFID application for a mixed-product assembly line

Due to its scale, complexity, and uncertainty of the processes, the management and control of automotive manufacturing systems have been very challenging. With the recent application of new technologies such as radio frequency identification (RFID) to manufacturing process, real-time information has become available in manufacturing systems through IT infrastructures. It is expected that RFID-based real-time information will increase timeliness and efficiency in decision making and drastically reduce uncertainty. That, in turn, will enhance both productivity and quality. This paper presents an advanced RFID application for automotive assembly processes, specifically, dynamic material dispatching (e.g., auto assembly parts). The application is uniquely advanced in that it integrates RFID technology with a real-time decision support system to ensure the accurate and efficient delivery of auto parts to mixed-product assembly lines. In this application, we have described the problem as a mixed-integer programming model, proposed a heuristic algorithm that incorporates the available RFID information, and assessed the value of RFID through a scenario-based analysis. We hope this paper may help contribute to a virtuous cycle of RFID innovation and applications in the manufacturing sector.     

A Prototype Genetic Algorithm-Enhanced Multi-Objective Scheduler for Manufacturing Systems

This paper describes the development of a prototype genetic algorithm-enhanced multi-objective scheduler for manufacturing systems. A framework of the prototype scheduler is proposed which accepts data input from a database or file and outputs a near-optimal schedule. A scheduling toolbox with scheduling models for job shop, flow shop and cellular manufacturing, forms part of the prototype scheduler, and the schedule builder transforms the near-optimal solution into a valid shop floor schedule. The prototype system was validated for various cases, with and without constraints and multiple objective functions, (makespan and tardiness), enforced simultaneously with constraints. In the first case, the schedule generated was comparable to those obtained by other researchers. The prototype system was also tested for its ability to handle dynamic scheduling, e.g. a rush order. The results showed that all the job orders could be rescheduled within the original makespan, even though the order of one of the jobs was doubled.     

An ISA-95-based manufacturing intelligence system in support of lean initiatives

Increasingly, lean manufacturing is being applied by leading manufacturers throughout the world. As continuous improvement cycles of many lean initiatives focus on cost control and improving quality of product, turbulence in world markets demand more agility and responsiveness without compromising cost and quality. In order to attain more agility, information and communication technologies are utilized by many manufacturers, both at shop floor systems and enterprise resource planning (ERP) layer. This increasing trend created a disconnect that presents an opportunity for manufacturing intelligence (MI) systems. Bridging this gap, MI can enhance responsiveness by providing visibility into operations and improve quality by tracking long-term data, hence support the continuous improvement philosophy of lean manufacturing. This paper presents an ISA-95-based MI framework that can support lean manufacturing by contextualizing low-level shop floor data using production operation information from ERP systems. Processed data is presented on dashboards via Key Performance Indicators, which managers can use to determine appropriate action for their lean initiatives, timely and effectively.     

Hybrid shop floor control system for Computer Integrated Manufacturing (CIM)

A shop floor can be considered as an important level to develop Computer Integrated Manufacturing system (CIMs). However, a shop floor is a dynamic environment where unexpected events continuously occur, and impose changes to the planned activities. To deal with this problem, a shop floor should adopt an appropriate control system that is responsible for the coordination and control of the manufacturing physical flow and information flow. In this paper, a hybrid control system is described with a shop floor activity methodology called Multi-Layered Task Initiation Diagram (MTD). The architecture of the control model contains three levels: i.e., the shop floor controller (SFC), the intelligent agent controller (IAC) and the equipment controller (EC). The methodology behind the development of the control system is an intelligent multi-agent paradigm that enables the shop floor control system to be an independent, an autonomous, and distributed system, and to achieve an adaptability to change of the manufacturing environment.     

A formal model for incorporating shop floor controls into plant information systems

The high cost and long development cycle of shop floor controls (SFC) have prevented many small, medium, and even large-size manufacturers from deploying plant-wide, real-time information systems. In order to stay competitive in a make-to-order business model, such systems are essential. In addressing the obstacles to such systems, this article proposes a formal method that ensures that a built SFC can be applicable to a plant-wide, real- time information system. By taking advantage of both the linear growth of the complexity function in a structured adaptive supervisory control model, and the real-time responses of a virtual production line based e-Manufacturing system, a formal method for creating an integration-ready structured adaptive supervisory control model (iSASC) for a discrete manufacturing system is introduced. An iSASC-based SFC prototype system was successfully tested and evaluated in an industrial site.     

A Multi-Agent-Based Agile Shop Floor Control System

The ability of an enterprise to deliver new products quickly and efficiently to market is often the chief determinant of competitive success. The shop floor control system must be an open dynamic system with the capability of adapting and accepting radical unpredictable changes in its structures and industrial practices. This paper presents a new architecture for an agile shop floor control system. The architecture is based on the methodology of multi-agent systems in distributed artificial intelligence (DAI). The multi-agent system has some common characteristics such as: distribution, autonomy, interaction, and openness, which are helpful for transferring traditional architecture to a distributed, cooperative architecture for a shop floor control system. A bidding method based on the required production cost and processing time is also proposed. Using a distributed object-oriented technique, a CORBA-based multi-agent framework for an agile shop floor control system is constructed to integrate all the activity of the shop floor into a distributed intelligent open environment. To implement the framework, a coordination model between agents and behavioural models of some representative agents are established.     

基于工作流的制造企业应用集成框架研究

在阐述工作流定义、工作流管理系统的组成和应用的基础上 ,分析研究企业应用集成中的工作流关键技术 ,总结目前工作流建模、工作流分析、工作流执行和工作流互操作技术存在的不足 ,提出基于工作流的制造企业应用集成框架结构。这种基于工作流的制造企业应用集成既能有效实现PDM、ERP、SCM、CRM之间跨越时空、地域和供应链的信息集成 ,又能在人和应用间实现有效协同 ,最终实现系统的全局优化发展     

A blackboard-based process planning system for the surface mount manufacture of PCBs

This paper describes a real-time computer-aided process planning (CAPP) system for printed circuit board (PCB) assembly using surface mount technology. The prototype, dynamic, realtime CAPP system described uses a blackboard to integrate multiple knowledge sources (knowledge bases) in implementing the process planning procedure. The CAPP system is implemented using the expert system environment (ESE) and structured query language (SQL). The system uses two subsystems (knowledge bases). They are a planning subsystem which performs the static process planning task and a dynamic information processing subsystem which considers the real-time changes on the shop floor and routes the PCB assembly flow. The integrated system developed generates process plans that can be implemented in real time. The use of the blackboard concept for CAPP architecture is unique and well suited for this task.     

APPLICATION OF IMPROVED PRODUCTION ACTIVITY CONTROL ARCHITECTURE FOR SHOP FLOOR INFORMATION SYSTEM IN DIGITAL MANUFACTURING

Shop floor control (SFC) is responsible for the coordination and control of the manufacturing physical and information flow within the shop floor in the manufacturing system. Weaknesses of the production activity control (PAC) architecture of the shop floor are addressed by the Maglica's new system architecture. This architecture gives rise to unlimited number of movers and producers thus evolving more complex but decentralized architecture. Beijing Institute of Technology - production activity control (BIT-PAC) architecture introduces an idea of sub-producers and sub-movers thus reducing the complexity of the architecture. All the equipments including sub-producers and sub-movers are considered to be passive in the proposed shop floor information system. The dissemination of information from sub-producers and sub-movers is done manually through a PC. Proposed BIT-PAC SFC architecture facilitates the information flow from shop floor to the other area of the organization. Effective use of internet information services (IIS) and SQL2000 is done along with the ASP.NET technology to implement the application logic. Applicability of the software based on BIT-PAC architecture is checked by running application software on a network PC that supports the dynamic flow of information from sub-producers and sub-movers to the other parts of the organization. Use of software is also shown at the end for BIT training workshop thus supporting the use of SFC architecture for similar kind of environments.     

基于多Agent和动态逻辑制造单元的车间控制系统研究

根据敏捷化生产的要求，分析车间控制系统的多Agent层次结构，提出动态逻辑制造单元的概念，用于组织车间制造系统资源，实现在动态多变的环境中车间制造系统快速重组，动态重构的能力，研究在动态逻辑制造单元的组织形式下，面向订单的生产调度的实现方法，并给出了车间多Agent系统的软件体系结构。     

RFID-based colored Petri net applied for quality monitoring in manufacturing system

Product quality is difficult to be traced and monitored in the distributed manufacturing network. This paper proposes and develops a new RFID-based CPN modeling method where the colored tokens are evolved to color-tagged tokens carrying the product information of real-time status. With this new real-time modeling method, the performance of manufacturing systems such as yield rate and throughput can be realized. In this paper, a case study has been conducted to examine the feasibility and effectiveness of the proposed method. The simulation results show that the new modeling method is able to complete the preliminary real-time quality status analysis of a manufacturing system so as to handle dynamic and stochastic manufacturing network effectively and enable decision making for process improvement.     

A collaborative manufacturing execution platform for space product development

Space product development enterprise has the feature of single piece or small batch productions, in which the product manufacturing process changes frequently, key components need process preparation, and production scheduling problem is often complicated. According to the development process of space products, a collaborative platform under network-based manufacturing environment for space products development is proposed in this paper. The main structure of the platform and the cooperation process between each application modules are proposed. Moreover, a kind of dynamic job shop scheduling algorithm is presented. The algorithm is used to realize rapid response and adjust manufacturing plan when production or process plan has changed. Finally, a prototype system that supports space product manufacturing process management is developed and a case study is presented to demonstrate the efficiency of proposed algorithm.     

基于数字孪生的复杂产品离散装配车间动态调度

面向多品种变批量生产的复杂产品离散装配车间是典型的复杂制造系统,其运行过程呈现高复杂性、强动态性和不确定性因素多等特征,为实现复杂产品离散装配车间的动态调度,提出一种基于数字孪生的复杂产品离散装配车间动态调度方法,通过物理空间和虚拟空间之间的数据交互进行更精确的动态调度.构建了基于数字孪生的复杂产品离散装配车间调度框架...     

基于实例推理的实时CAPP系统研究

现代生产不仅要求工艺设计系统能够快速响应产品的变化 ,而且要求所编制的工艺规程实用可行。本文开发了一种基于实例推理的实时CAPP系统 ,通过实例推理技术表示以往的工艺规程 ,同时考虑车间的加工能力 ,并将加工后零件的误差信息即时反馈回系统 ,从而快速、实时地生成符合生产要求的工艺规程。由于成功与失败的设计实例都被存入实例库中 ,系统实现了自学习功能 ,推理能力得到不断增强 ,最后通过回转类零件工艺设计实例验证了该系统的有效性     

基于MES的生产车间管理信息系统

针对制造企业在实施生产管理信息化过程中存在的问题,提出以制造执行系统(MES)为核心的三层结构———企业资源计划(ERP) /制造执行系统(MES) /过程控制系统(PCS)的生产管理信息化的实施方案,用于解决生产与计划相互脱节的难题,实现了车间的现场调度、生产过程控制、在线质量控制,以及对生产过程中“非常规信息”的控制与管理,加强了制造计划的可执行性。