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.     

FMS的CONWIP控制

生产存储控制是FMS设计的重要方面之一。CONWIP控制系统可以保证有效地使用昂贵的FMS设备的同时,使FMS满足顾客的需求,为此,对CONWIP控制下的FMS进行仿真,以分析不同处理时间对CONWIP控制下的FMS性能的影响。     

System identification for generic model control

System identification methods build mathematical models of dynamical systems based on observed data. The intended use of the model should always be reflected in the methods and techniques used for identification. In this paper an identification scheme is derived for the case where the model is going to be used for GMC controller design. The aim of GMC control is to make the output approach a setpoint along a given desired trajectory. This is reflected in the identification scheme which is non-standard in two ways. Firstly, the emphasis is on the output trajectories of the models, and secondly we try to make the prediction errors follow an error trajectory determined by the controller parameters. Simulation studies are included which show that the derived identification scheme performs well.     

Solution of scheduling problems of job-shop type FMS with alternative machine tools

FMS is now expected as one of the measures to cope with the recent requirements for the production. To elevate the performance of the FMS, it is necessary to establish its design methodology by which the flexibility and compatibility of the system functions can be determined. In this regard, one of the most important technical subjects is how to solve problems arising from machine breakdown to ensure optimum use of the system performance.

This paper deals with a scheduling problem of a job-shop type FMS with machine breakdown, taking into account alternative machine tools for each machining process of parts. The problem is solved by a discrete event simulation using SLAM II simulation language. Performance of the system is measured in terms of the machine utilization, mean flow time, total production, number of workpieces in-progress, and makespan.     

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.     

基于扩展随机高级判断Petri网的FMS调度和仿真

本文提出一种新的更适合FMS调度仿真的扩展随机高级E-net,简称ESHLEP-N(Extended stochastic High Level Evluation Petri Net)。以ESHLEP-N模型为基础,设计并建立了FMS调度仿真专家系统。借助于该系统提出并研究了新的旨在减少空闲(no-inputs)和阻塞的实时动态再调度规则。经过仿真,证明新规则的产率(throughput)比传统规则平均提高6.48％。本文的部分成果已经用于航空航天部159厂的高级DNC系统的设计之中。     

可重构容错多机FMS控制系统YH-MCS

本文介绍了我们设计和实现的可重构容错多机柔性制造控制系统ＹＨ—ＭＣＳ的软硬体系结构和技术特点。     

一类FMS的最佳活Petri网模型的综合

利用Petri网为一类柔性制造系统建模,并讨论避免系统死锁问题.通过Petri网模型的结构分析,证明了系统产生死锁的一个充分必要条件.给出了避免死锁的最佳控制器,它可以通过给系统的Petri网模型增加一些新的位置与相应的弧来实现.从而导出了这类制造系统的最佳活Petri网模型.     

离散系统快速递推仿真算法及其在柔性制造系统中的应用

本文对具有中央服务台形式,队列均为FCFS服务规则,不同顾客类不同路径和不同服务速率的闭网络进行了研究。文中引入多变量排队网络理论建立了一类离散事件系统仿真模型,提出一快速递推算法,该算法计算量小并应用于实际问题。     

FMS智能故障诊断专家系统的建立和开发

采用基于人工智能的故障诊断专家系统方法，附以模糊数学、神经网络、机器学习、数据库等理论，解决故障诊断中知识的合理表达，基于符号和数值的多种快速推理机制，知识的自动获取及知识库智能化管理等关键技术，建立了一个智能模糊故障诊断专家系统。     

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....     

Adaptive generic model control for a class of nonlinear time-varying processes with input time delay

In this article, an adaptive control approach––Adaptive Generic Model Control (AGMC) for a class of nonlinear time-varying processes with input time delay is proposed. First, a nonlinear state predictor (NSP) is introduced, which extends the conventional generic model control (GMC) to a class of nonlinear processes with input time delay. Then a class of nonlinear time-varying processes with input time delay is further considered. A modified strong tracking filter (MSTF) is adopted to estimate the time-varying parameters of the nonlinear processes, and the state estimates are then utilized to update the plant models used in the NSP and MSTF, this results in an adaptive generic model control scheme for a class of nonlinear time-varying processes with input time delay. A modified mathematical model of a three-tank-system is used for computer simulations, the results show that the proposed AGMC algorithm is satisfactory, and it has definite robustness against model/plant mismatch in the measurement noise.     

An extensible,generic environmental process modelling framework with an example for a watershed of a shallow lake

We present a modelling framework for the generation of environmental process models. The framework builds on the Direct Computer Mapping method with an editable, process network based expert module and interpreter. The expert interface supports mapping of objects from the GIS layers onto the prototyped state, transition and connection elements of the case specific generic process model. The developed general purpose interpreter generates the standardized declarative facts and clauses, describing the actual model with the locally executable program prototypes. This input is executed by the general kernel. The model interpreter generates also the case specific templates for the (optionally web based) user interface, while map-server utilizes the GIS shape files of expert model. The implementation supports the extension of the model with new components in space and time. The framework is illustrated by an example for the watershed of Lake Balaton.     

Developing a General Control Criterion for Complex Systems

A mathematical expression for the minimum consumption control criterion is derived. It can be used in comparative evaluation of complex systems in analysis and scheduling problems and as a general control criterion. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 183–186, September–October 2005.     

Implementing a generic component‐based framework for telecontrol applications

The rapid growth of telecontrol systems is one of the major trends in today's network‐oriented community. The implementation of generic frameworks, consisting of reusable components that can form the basis for the development of such systems, is a necessity. There is a plethora of associated applications that can be developed in a distributed environment, such as audio/video teleconferencing, groupware and collaborative computing environments, remote controlled services, etc. In this paper we design and implement a generic framework of components that can be used for the realization of telecontrol applications. This category of applications focuses primarily on the issues of managing distributed units on remote end‐systems. Such applications contain remote units and administrators that are connected and exchange data and control messages. We analyse the outlined architecture of our framework and the most important system operations. We also describe the communication protocol used in message exchanges between the constituent components. Finally, we illustrate the usefulness of our framework by presenting two applications that were created by extending the basic software infrastructure. Copyright © 2007 John Wiley & Sons, Ltd.     

小卫星对上面级定向的姿控设计与验证

本文针对小卫星对上面级的快速定向问题,设计了小卫星对上面级定向的姿控方案,设计了基于陀螺的4阶龙格库塔积分算法与递阶饱和PD控制算法,首先通过数学仿真初步验证了姿控方案、姿控算法设计的正确性。在此基础上,搭建了小卫星姿控系统半实物仿真平台,并开发了相应的仿真软件,进行了飞轮开环跟踪与飞轮闭环跟踪的小卫星姿控系统半实物仿真,进一步验证了姿控方案、姿控算法设计的正确性。最后经过飞行试验,根据实际飞行结果,证明了姿控系统设计的正确性。     

Development of an agent-based Virtual CIM architecture for small to medium manufacturers

Today's global competitions are forcing enterprises to rely on integrated manufacturing systems to satisfy constantly changing market requirements. Whereas Small to Medium Enterprises (SMEs) often feel difficult to compete with large organisations due to having insufficient resources. By integrating resources of many partners, the SMEs can form global integrated manufacturing systems in the form of Virtual CIM (VCIM) and thus achieve a competitive edge. VCIM is a concept towards integrating globally distributed manufacturing resources across enterprise boundaries. In order to implement VCIM, this research project develops an agent-based architecture to support the integration and scheduling of distributed manufacturing resources. This architecture accommodates all agents for VCIM with a three-layered structure and permits new agents to be connected with the existing structure through the Internet when and where necessary. In this architecture, many Facilitator agents coordinate activities of manufacturing resources in a parallel manner. Meanwhile, the Facilitator agents achieve proposal messages through agent negotiation based on distributed resources’ real time information and use a backward network algorithm for shortest-path to perform optimisation for resource allocation. With these approaches, an optimised production schedule has the lowest cost as the primary criteria and the shortest production time as the secondary criteria while satisfying customer required due date/time and delivering destination.     

可载人自平衡移动机器人控制系统设计

本文提出一种自平衡移动机器人。结合系统的功能要求,构建了遥控自平衡控制模式的机器人运动控制系统,提出了以PC/104工控机+数字I/O卡+电机驱动器为控制模式的嵌入式控制系统,保证了硬件系统具有良好的可扩展性、灵活性、实时性、低功耗的特点;并完成了机器人载人前进、后退,验证了设计方法的有效性。