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 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.     

Integrated control [production control]

In a modern manufacturing enterprise the shop floor must be an integral part of the whole organisation. The author explains how the entire production process, from material supplier to customer, must be optimised     

面向状态的车间控制策略研究

当前的生产计划和控制系统较好地解决了企业中期的物料需求计划与能力需求计划问题,而车间以下层次的生产作业计划与控制是其薄弱环节。这里通过对现代车间生产活动控制的功能、目标和现代车间制造系统基本特征的考察、分析,揭示了现代车间控制的根本矛盾,提出了面向状态的车间控制策略和方法并进行了应用研究。     

Automatic control of a One-of-a-Kind Production cell

This paper reports the outcome of a research project which aims to solve the problems in automatic control of the shop floor in One-of-a-Kind Production (OKP) through developing a prototype control system for an experimental OKP cell at the laboratory. The main problems in automatic control of the shop floor in OKP are the frequent changes of product structure or type and consequent changes of production system configuration. These changes in OKP make it necessary to have a highly flexible and robust automatic control system. To resolve the problems, a distributed control system has been developed at the CIM laboratory of the Department of Production, Aalborg University, Denmark. This control system has enough flexibility and robustness to cope with the aforementioned changes in OKP. To support the design and implementation of the control system, several concepts, algorithms and control principles, such as task logic routes, address code of production resources, automatic task decomposition algorithm, generic control modules and distributed control principles are also proposed in this paper.     

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.     

生产车间混合式控制结构模型和协商机制研究

为了提高车间控制系统的柔性、开放性和全局优化性能,在分析现有车间控制体系结构的基础上,融合Agent技术,提出了一种适应性混合式车间控制系统体系结构模型。该模型利用递阶结构将控制功能设计成系统优化Agent、单元协调Agent和单实体Agent三层结构,并允许同层Agent及上下层Agent之间的协商。为了进一步提高协商效率,集成分布式协商和全局控制,设计了基于招投标机制和示例学习方法的协商机制,详细分析了包括时间约束算法和基于示例的学习方法的协商机制核心算法。在JADE(Java Agent development framework)平台上构建了原型系统。     

Stigmergic cooperation mechanism for shop floor control system

Inspired by the collective behaviour of ant colonies, a stigmergic cooperation mechanism for shop floor control is proposed. In stigmergic shop floor control systems, one piece agent takes charges of one work piece and chooses a manufacturing resource for it in the light of pheromones stored in information environment. Piece agents also update these pheromones to guide subsequent agents routing. Experiments confirm that a stigmergic cooperation mechanism has an excellent scheduling performance in a static environment, good suitability for the stochastic machining-time problem and good adaptability to shop floor changes.     

Shop-floor control

Any company that wishes to be a world class manufacturer must first gain full control of its shop floor processes. The author tells the story of one such company. Early in 1993, Nortel Defence Systems (now Cogent), part of the global telecoms corporation Northern Telecom (Nortel), opened a new facility on a greenfield site in Newport, South Wales. The Newport facility is purpose built, and includes, among other areas, a major area for the production of specialist and complex cables, both electrical and fibre optic. Manufacturing is normally for one off items and includes prototype cables, using product and process development. Cogent Defence Systems consists of several businesses, which have extensive experience in communications for secure and harsh environments. One of Cogent's business policies is to become a world class manufacturer. `Policy' is a business requirement; its solution is strategy. The solutions determined to support this strategy are summarised. The strategy developed so far includes the implementation of shop floor control, followed by finite capacity planning and scheduling. Materials requirements, calculated to the finite capacity plan, are identified next, with the company forming closer links with suppliers. Meanwhile, continuous improvement philosophies are being put into place     

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.     

Flexible control [shop floor control]

Adaptability in shop floor control is vital as production processes constantly change and improve. The author outlines the requirements for modelling manufacturing systems using an object-event-action methodology     

MODELING AND IMPLEMENTATION OF A DISTRIBUTED SHOP FLOOR MANAGEMENT AND CONTROL SYSTEM

Adopting distributed control architecture is the important development direction for shop floor management and control system, is also the requirement of making it agile, intelligent and concurrent. Some key problems in achieving distributed control architecture are researched. An activity model of shop floor is presented as the requirement definition of the prototype system. The multi-agent based software architecture is constructed. How the core part in shop floor management and control system, production plan and scheduling is achieved. The cooperation of different agents is illustrated. Finally, the implementation of the prototype system is narrated.     

基于Flexsim仿真的FMS车间级控制系统开发

在研究车间级控制系统与仿真控制理论的基础上,构造了基于仿真的FMS车间级控制系统模型,并结合北京交通大学教学型FMS,在Flexsim中进行系统建模,完成了该FMS的车间控制系统的设计与开发,实现了仿真和实际控制逻辑的共用.     

A step towards real time [production monitoring and control system]

The Fraunhofer Institute for Information and Data Processing has developed a novel production monitoring and control system (PMC) for DaimlerChrysler Bremen for its C-type car which will begin production in 2007. Called the Provis.Agent, it is the first agent-based PMC system for distributed real-time production monitoring that allows integration with other shop floor related applications.     

面向重组的车间控制器系统

本文以车间层计划调度功能为主线，分析了引入重组思想车间控制器计划调度功能的改进，以及相应控制结构的变化，并以此为基础开发了一个面向重组的车间控制器软件系统。     

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。     

CAC-CIMS生产线控制的研究和开发

成都飞机公司计算机集成制造系统(CAC CIMS)的生产线自动化控制系统由车间控制器、单元控制器(含制造工作站模块)和DNC接口(含设备)三层递阶结构组成.单元控制器与DNC接口构成柔性分布式数控(FDNC),它与车间控制器共同构成对制造过程的滚动控制.本文以CAC CIMS中车间控制器、单元控制器和DNC接口的研究和开发为背景,着重对生产线控制的递阶结构、系统功能和运行等进行论述.     

基于多代理技术的车间计划与调度研究

对分布式车间生产计划与调度过程进行了研究,并在基于多代理（multi-agent）的车间管理控制系统中实现。     

A new method for grinder dressing fault mitigation using real-time peak detection

To facilitate the implementation of machine monitoring algorithms on the shop floor, signal processing and decision-making strategies must be developed, which account for the difficulties associated with monitoring a machine in an industrial environment. Therefore, this paper focuses on introducing a new method for dresser contact detection, which takes into account sensor and data acquisition system costs, computational limitations of an embedded detection system, and noise robustness issues associated with shop floor implementation. This paper also discusses the way in which the monitoring algorithm directly interfaces with the machine control in real time in order to ensure that system faults are avoided. Furthermore, the new algorithm is compared with more traditional methods for change detection by applying each algorithm to the signal output from a dresser horsepower sensor. In an industrial application, the new algorithm is shown to provide zero missed detections, zero false alarms, and a sufficiently fast response time.     

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.