Assessment of manufacturing systems reconfiguration smoothness

The effect of the configuration selection on the smoothness and easiness of manufacturing systems reconfiguration process cannot be neglected, especially when dealing with reconfigurable manufacturing systems (RMS). The term “reconfiguration smoothness” is introduced in this paper to address this issue. In order to evaluate the level of reconfiguration smoothness (RS), a metric was developed to provide a relative measure of the expected cost, time, and effort required to convert from one configuration to another. This metric is composed of three components representing different levels of reconfiguration, namely; market-level reconfiguration smoothness (TRS), system-level reconfiguration smoothness (SRS), and machine-level reconfiguration smoothness (MRS). Rules are introduced to guide the development of execution plans for system-level reconfiguration, which we call “reconfiguration planning”. These plans help reduce the physical effort of reconfiguring the system. A case study is presented to demonstrate the use of the developed metric followed by sensitivity analysis to show the effect of changing different metric parameters. The results show how the developed metric provides a powerful relative assessment tool for the transitional smoothness between a current configuration and a number of candidate feasible configurations for the next period. This can affect the configuration selection decisions at the beginning of each configuration period.     

可重构单元模块化及其结合面动特性的研究

通过对可重构制造系统(RMS)关键技术的研究，分析讨论了单元模块化对RMS的重要意义，指出了模块化设计在具体实现过程中存在的问题。给出了可重构制造单元模块的定义以及阐明了最小运动模块的具体划分。为管理、配置模块，给出了模块的组合数学模型，这有助于模块分类、排列以及组合。根据模块组合数学模型，总结出可重构单元模块接口即结合面的特点。运用分形技术，对模块结合面接触刚度的研究，得到了重构后结合面表面粗糙度与分形维数的关系原型以及接触刚度，为研究模块重构后形成的装备的动态特性、精度以及可靠性奠定基础。     

可重组制造系统

可重组制造系统是一种能够快速响应新的生产环境的新型制造系统，在快速响应市场变化和个性化生产方面具有重要的意义。阐述了可重组制造系统的发展历史、概念、分类、重组特性及其特点，评述了目前可重组制造系统的研究现状，讨论了可重组制造系统的关键技术，并提出了可重组制造系统应用研究的发展方向。     

可重构制造系统理论研究

在已有定义基础上给出了可重构制造系统(RMS)的定义,分析了RMS与刚性制造系统(DMS)、柔性制造系统(FMS)的区别。建立了RMS的结构和组成、类别及理论体系,将RMS基础理论概括为系统随机建模、布局规划与优化、构件集成整合、构形原理、可诊断性测度和经济可承受性评估6个方面,并提出了RMS使能技术。     

面向多品种变批量的可重构制造系统的设计方法研究

可重构制造系统的设计目标是要确定各种零件的生产周期、各种零件之间的生产顺序与加工各种零件所用的组态。建立了各生产周期成本模型、重构成本模型与全生产周期成本模型。由各种零件的批量确定加工各种零件的标准生产周期，分析系统成本冗余，得到了多组偏差生产周期，求出了各种生产周期下各种零件之间所有生产排序的K-优组态路径。通过比较所求得的组态路径，可以获得一条最优与多条次优组态路径。用案例验证了所提出的方法。     

Configuration Selection for Reconfigurable Manufacturing Systems by Means of Characteristic State Space

The configuration selection for reconfigurable manufacturing systems(RMS) have been tackled in a number of studies by using analytical or simulation models. The simulation models are usually based on fewer assumptions than the analytical models and therefore are more wildly used in modeling complex RMS. But in the absence of an efficient gradient analysis method of the objective function, it is time-consuming in solving large-scale problems by using a simulation model coupled with a meta-heuristics algorithm. In this paper, a new approach by means of characteristic state space is presented to improve the efficiency of the configuration selection for an RMS. First, a characteristic state equation is set up to represent the input and the output resources of each basic activity in an RMS. A production process model in terms of matrix equations is established by iterating the equations of basic activities according to the resource flows. This model introduces the production process into a characteristic state space for further analysis. Second, the properties of the characteristic state space are presented. On the basis of these properties, the configuration selection in an RMS is considered as a path-planning problem, and the gradient of the objective function is computed. Modified simulated annealing(SA) is also presented, in which neighborhood generation is guided by the gradient to accelerate convergence and reduce the run time of the optimization procedure. Finally, several case studies on the configuration selection for some actual reconfigurable assembly job-shops are presented and compared to the classical SA. The comparison shows relatively positive results. This study provides a more efficient configuration selection approach by using the gradient of the objective function and presents the relevant theories on which it is based.     

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.     

一种面向对象Petri网的构造及应用研究

将 Petri网理论与面向对象技术结合 ,并借鉴客户机 /服务器模式 ,着色 Petri网中的一些概念 ,提出了一种新的面向对象 Petri网。文中详细论述了这种面向对象 Petri网的结构 ,形式定义 ,运行规则 ,并给出了这种面向对象Petri网应用于制造系统中的一个建模实例     

Modeling and controling the FMS of a welding robot

For complex welding, Petri net (PN) theory is adopted to model a welding flexible manufacturing system (WFMS) in this paper. When the model called the multi timed color Petri net (MTCPN) was designed, a professional simulation software package was used to test it theoretically. Then, a scheduling method was devised to optimize the conflicting information in the model. A welding experiment based on the model is carried out. The results of the welding experiment and the model simulation show that the modeling method is correct and feasible. This research presents a new way to optimize a WFMS and it develops the application area of PN theory.     

可重组制造系统组态模型及其实现技术

分析了可重组制造系统(reconfigurable manufacturing system,RMS)的特性及其对组态的影响,提出了可重组制造系统的基于全生命周期的组态模型。在实现技术方面,首先运用图论的方法探讨了组态计划问题,分别给出了3个层次的计划模型及解答,然后根据组态模型的功能要求提出了组态平台的基本结构,最后通过工程实例验证了该模型及其实现技术的适用性。     

基于多Agent的可重构制造系统故障诊断模型

可重构制造系统对故障诊断有更高的要求。提出了一种基于多Agent的可重构制造系统故障诊断模型,模型为3层结构,从下向上分别为监测Agent层、诊断Agent层和管理Agent层,分析了模型的故障诊断机理,讨论了模型中Agent间的通信与协作。最后例子表明了可重构制造系统重构前后,该模型均能有效完成故障诊断。     

Effect of reconfiguration costs on planning for capacity scalability in reconfigurable manufacturing systems

In a globally competitive market for products, manufacturers are faced with an increasing need to improve their flexibility, reliability, and responsiveness to meet the demands of their customers. Reconfigurable manufacturing systems (RMS) have become an important manufacturing paradigm, because they broadly encompass the ability to react efficiently to this environment by providing the exact capacity and functionality needed when needed. This paper studies how such new systems can manage their capacity scalability planning in a cost effective manner. An approach for modeling capacity scalability planning is proposed. The development of the model is based on set theory and the regeneration point theorem which is mapped to the reconfigurable manufacturing paradigm as the capacity scalability points of that system. The cost function of the model incorporates both the physical capacity cost based on capacity size and costs associated with the reconfiguration process which referred to as the scalability penalty cost and scalability effort cost. A dynamic programming (DP) approach is manipulated for the development of optimal capacity scalability plans. The effect of the reconfiguration costs on the capacity scalability planning horizon and overall cost is investigated. The results showed the relation between deciding on the optimal capacity scalability planning horizon and the different reconfiguration costs. Results also highlighted the fact that decreasing costs of reconfiguration will lead to cost effective implementation of reconfigurable manufacturing systems.     

基于ECA规则的适应性工作流技术研究

工作流管理系统能够给企业的业务运行提供有力支持。但是，目前的工作流管理系统对过程模型的表达过分简化，影响了它在实际应用中的效果。为了提高工作流管理系统的适应性，文中形式化地定义了适合于工作流的ECA规则。在此基础上提出了基于ECA规则的工作流模型，并将该模型与基于Petri网和基于UML活动图的工作流模型进行了比较。提出了一种基于事件表达式重写策略的事件检测方法，以提高工作流引擎的执行效率。最后，介绍了一个基于ECA规则的工作流技术的应用系统。     

Petri网在基于规则系统一致性问题检查中的应用

基于规则系统是目前应用较为广泛的一类专家系统,但它的知识库不易维护。本文针对基于规则系统的一致性问题,应用图形化建模工具Ｐｅｔｒｉ网的可达性概念和状态方程分析方法,提出了基于Ｐｅｔｒｉ网的一致性检查方法。文中首先对规则的三种Ｐｅｔｒｉ网表示模型进行了比较,并在含约束Ｐｅｔｒｉ网模型基础上,提出了一致性检验的命题方法,最后以实例说明该方法的实现步骤。当规则库较大时,相应的Ｐｅｔｒｉ网模型可能也会很庞     

Construction and performance analysis of a Petri net model based on a functional model in a CIM system

The so-called functional models, such as IDEF0, are useful tools for describing, designing and analysing the functional aspects of a complex manufacturing system, for example a CIM (computer integrated manufacturing) System. Though it involves considerable time and cost to build a sound functional model, the model usually cannot be used directly in further systems analysis procedures, such as quantitative performance analyses, due to its informal nature. To overcome this problem, we suggest a Petri net based procedure. First, we build a Petri net model from the IDEF0 and IDEF3 models, both of which are functional modelling tools widely used in real applications. Then, employing steady-state analysis for the Petri net, we propose a method to obtain performance measures such as the production rate. Since the analytical ability of a Petri net diminishes with increasing manufacturing system size, we develop a technique to aggregate and consolidate the Petri net to alleviate this problem that is associated with increasing complexity. An example problem is included to show the viability of our method for constructing a Petri net from a functional model and to evaluate the performance of the Petri net in an analytic manner.     

可重构数字式机电测控试验平台的研制

提出采用可重构制造思想来研制数字式机电测控试验平台 ,介绍了试验平台的系统结构、功能和基本原理 ,按照可重构制造原理对试验平台的软、硬件模块进行了划分 ,对可重构制造系统理论在试验平台中的应用作了分析和探讨。     

基于扩展随机Petri网的可重组制造系统建模与分析方法

可重组制造系统(Reconfigurable manufacturing system,RMS)可根据市场变化进行组态调整和组元升级,系统的建模与分析方法必须能适应上述特点。提出基于扩展随机Petri网(Extended stochastic Petri nets,ESPN)的模块化建模方法,将RMS不同的加工资源对应于相应的ESPN基本模块,并通过过渡变迁合成ESPN模型,该模型能适应任意分布的制造系统,可更加精确地反映生产过程。在此基础上采用基于行为表达式的分析方法,得到系统性能指标,该分析方法可不必画出可达图而直接得到系统性能关系函数,使分析过程更加直观、简洁。可重组电动机生产线的实例证明了该建模与分析方法的有效性。     

Graph theory-based approach to optimize single-product flow-line configurations of RMS

Generating economical and distinctive configurations for a given demand period is an important optimization problem for reconfigurable manufacturing systems (RMS) at both initial design and reconfiguration stages. This paper presents a graph model to optimize capital cost of singe-product flow-line (SPFL) configurations of RMS. The parameters of the SPFL configuration include number of workstations, number and type of machines and assigned operations for each workstation. The full topological sorting and graph augmentation procedures are developed to derive a combined machine graph from the operation precedence graph of a specific product. Then a two-phase optimization approach is proposed. In the first phase, the optimal and K-1 suboptimal configurations are generated by solving a constrained K-shortest paths problem on the machine graph. In the second phase, a dissimilarity index is introduced to measure the dissimilarity between every pair of found configurations. Subsequently p distinctive ones out of K configurations are obtained using the algorithms for p-dispersion problem. Case studies illustrate the effectiveness of our approach and show some superiority of our approach compared to existing approaches. Computational experience shows that the approach is fit for small-to-medium size problems of configuration generation. The approach is also applied to optimizing SPFL in mechanical production.     

基于柔性制造系统的Petri网模型简化规则

为解决Petri网模型中的状态爆炸问题，提出了一种将简化规则应用到Petri网模型中的方法。该方法通过库所和变迁的合并与消除，来达到简化模型的目的。以柔性制造系统的加工站为例，建立加工站的Petri网模型，将简化规则应用到改进的加工站模型中。为了说明简化网保持了原网的外部功能，利用基于时序Petri网的时态逻辑规则进行了证明。结果显示，简化网在保持功能性的基础上，提高了验证和分析的效率。     

可重构制造系统工艺路线与系统布局设计研究

为使可重构制造系统的重构过程更加快速有效,提出了一种工艺路线和系统布局设计的方法.首先,基于图论构建了可重构制造系统工艺路线的有向网络模型,并采用Dijkstra算法和双向扫视算法,进行最优工艺路线和备选工艺路线的选择;然后,以工艺路线为基础,依据排队论中的相关理论,对制造系统的布局进行优化设计,以获得可重构制造系统布局方案.实例表明,该设计能够适应可重构制造系统快速多变的特征,提高对制造系统已有资源的利用率.