A STEP-based manufacturing information system to share flexible manufacturing resources data

The paper describes the design and implementation of a Manufacturing Information System as a solution to share and exchange manufacturing data. The Manufacturing Information System possesses relevant features for data sharing and exchanging, that are compliant to the standard ISO 10303, known as STEP¹. It is known that manufacturing planning and execution activities require data from machine-tools, robots, ASRSs², AGVs³ and, on the other hand, computer-based applications (CAM⁴, CAPP⁵ or PAC⁶) use proprietary formats to store flexible manufacturing resources data. The way the proprietary formats are built has lead to incompatibilities and interoperability problems among the applications. It is argued that by solving these problems a qualitative functional synergy will result during manufacturing planning and execution activities. The suggested solution is using a STEP-based information system, a server and a prototype client application. These three programs are implemented in Java classes to facilitate data sharing and exchanging of flexible manufacturing resources.This revised version was published in June 2005 with corrected page numbers.     

A survey of flexible manufacturing systems

In this report, the different flexible manufacturing systems used for machining and assembling in the following countries are reviewed: the United States, Japan, the Federal Republic of Germany, the German Democratic Republic, Italy, Great Britain, Sweden, Norway, France, Czechoslovakia and Hungary.Three categories of systems discussed are (1) flexible modules and units, (2) flexible transfer lines, and (3) “unaligned” flexible systems. Within each category are several sub-groups, divided up mainly according to the conveyor system and operating mode. This classification shows the effective French position in this field.     

Applicability of expert systems to flexible manufacturing

The following report will discuss the applicability and impact of knowledge-based systems in flexible manufacturing using the Integrated Manufacturing and Assembly System at the Machine Tool Laboratory (WZL), Technical University of Aachen, as a potential application case.     

Loading tools to machines in flexible manufacturing systems

This paper presents two models for loading tools to machines in a flexible manufacturing system (FMS) environment. Heuristic algorithms associated with the models are presented and discussed. The performance of each of the proposed algorithms is evaluated by testing on two hypothetical FMSs.     

装备制造企业如何选择柔性制造策略——基于制造合格率视角

柔性制造是装备制造企业应对制造稳定性干扰、提升竞争优势的重要手段.注意到现有文献较少关注制造稳定性与制造柔性量化这一不足,分别用制造合格率和制造冗余量刻画制造稳定性和制造柔性,并在此基础上构建一个关于装备制造企业制造合格率、制造柔性以及制造利润的统一分析框架,用以考察并揭示装备制造企业柔性制造策略对其应对制造稳定性的影响.研究结果表明:柔性制造策略的开展,有助于装备制造企业提高应对环境变化的能力,保证产品质量与数量,进而促进制造利润增长;当单位制造成本较小时,制造柔性水平与制造合格率呈倒U型变化趋势;当单位制造成本较大时,制造柔性水平与制造合格率呈正相关关系;单位质检成本的提高会迫使装备制造企业降低制造柔性水平,并影响企业应对制造稳定性的能力,最终导致制造利润受损.     

基于Petri网的柔性制造系统无死锁遗传调度算法

对以最小化加工时间为目标的柔性制造系统无死锁调度问题, 提出了一种遗传调度算法. 算法考虑到同类工件具有预先确定的相同加工路径, 而各工序的处理时间与工件有关. 用Petri网对工序和资源分配进行逻辑建模,利用遗传算法, 采用工序自然编码方式, 基于系统的最佳避免死锁Petri网控制器, 检测染色体的可行性, 修复不可行染色体使其对应的调度满足资源约束和无死锁控制约束, 从而保证算法所利用的所有染色体都对应系统的可行调度. 仿真结果表明了算法的可行性和有效性.     

A decision support algorithm for flexible manufacturing systems control

An application of a modification of Petri nets to mathematical modeling of discrete production processes utilized for a simulation of the flexible manufacturing systems is presented and an algorithm for the support of decision making in the control process of such systems based on the system model analysis is created. The algorithm makes the choice of a suitable control strategy possible in such a way that it automatically generates all potentially possible control strategies, automatically chooses the really possible ones and gives to an operator the chance to choose the most suitable realizable control strategy from the technological point of view.     

Managing for flexible software manufacturing

Contrary to popular belief, the most difficult problem in software reuse is not technical; rather, it is establishing a manufacturing culture. To manufacture software systematically, managers must provide three supporting pillars: development processes, infrastructure and culture. The author discusses these three issues     

Robots in flexible manufacturing systems

The use of computer controlled manufacturing systems incorporating robots and flexible control is of paramount interest today. A number of economists have noted that strength in high technology industries such as aircraft, missiles, communications, electronic and computers, in contrast to older industries, gives the economy of any country strong long-term growth prospects.During the past two decades, the concept of a flexible, programmable automation device, which has come to be known as an “industrial robot”, has become a reality. A variety of these automation modules have been developed, offering a wide range of capabilities and application possibilities. Robots currently help weld, cast, form, assemble, machine, transfer, inspect, load and unload parts into and out of a number of differing machines and processes.The first part of this paper analyzes the significance of FMS in industries today. The second part of the paper attempts to evaluate some of the areas of savings as a result of using robots.     

A hierarchic approach to production planning and scheduling of a flexible manufacturing system

The paper deals with the problem of improving the machine utilization of a flexible manufacturing cell. Limited tool magazine space of the machines turns out to be a relevant bottleneck. A hierarchic approach for this problem is proposed. At the upper level, sets of parts that can be concurrently processed (batches) are determined. At the lower levels, batches are sequenced, linked, and scheduled. Methods taken from the literature are used for the solution of the latter subproblems, and an original mixed integer programming model is formulated to determine batches. The proposed methods are discussed on the basis of computational experience carried out on real instances.     

A methodology for economic justification of flexible manufacturing systems

This paper develops a model for the economic justification of flexible manufacturing systems. The proposed model considers the intangible and tangible benefits resulting from the implementation of advanced computer controlled manufacturing systems. The model's structure consists of a top down approach which identifies and measures the desirability of the firm's global (strategic) as well as local (tactical) objectives.     

A rule-based robot scheduling system for flexible manufacturing cells

In this research we examine a class of flexible manufacturing cells (FMC) containing a robot. The role of the robot is to load parts onto machines, to unload parts from machines, and to transport parts between machines. Since the productivity of an FMC is directly proportional to the level of productive work performed by the robot, the manner in which robots move between machines affects productivity. The problem of finding efficient robot schedules/tours is therefore one of substantial economic significance in the operation of a FMC. Unfortunately, in many practical situations it is difficult to develop efficient robot schedules given the dynamic environments in which they exist. We devise a rule-based system to assist the cell supervisor in making good decisions by dynamically coordinating the available information during the production process. The rule-based system combines an algorithmic procedure to deal with a well-structured environment and a flexible heuristic approach employed to deal with less well-structured environments. Both the algorithmic and heuristic procedures are applied separately, then together, to control the robot's movement in a simulation experiment. We show that there is a predictable tradeoff between the quality of the resulting schedule and the information contents of heuristic used.     

Control principles in flexible manufacturing

Flexible manufacturing systems present a setting in which application of control concepts can be crucial. Today, some concepts are in place where needed, some are waiting to be applied, and some are yet to be created. This paper is a status report on FMS control technology, based on ongoing work at the The Charles Stark Draper Laboratory in the development of decision support systems for FMSs.     

Group scheduling problem: Key to flexible manufacturing systems

We present an efficient heuristic algorithm for determining the sequence which minimizes the makespan of a group scheduling problem at the first level. The problem, therefore, focuses on scheduling of parts (jobs) in a part family. In the generation of partial schedules at each iteration, a job with a high mean total processing time is given a higher priority than others. An example problem, chosen from a real world application, is used to implement, the algorithmic steps. For this example, it has also been shown that the makespan determine by the proposed heuristic is smaller than that determined previously by two documented algorithms.     

A flexible coefficient smooth transition time series model

We consider a flexible smooth transition autoregressive (STAR) model with multiple regimes and multiple transition variables. This formulation can be interpreted as a time varying linear model where the coefficients are the outputs of a single hidden layer feedforward neural network. This proposal has the major advantage of nesting several nonlinear models, such as, the self-exciting threshold autoregressive (SETAR), the autoregressive neural network (AR-NN), and the logistic STAR models. Furthermore, if the neural network is interpreted as a nonparametric universal approximation to any Borel measurable function, our formulation is directly comparable to the functional coefficient autoregressive (FAR) and the single-index coefficient regression models. A model building procedure is developed based on statistical inference arguments. A Monte Carlo experiment showed that the procedure works in small samples, and its performance improves, as it should, in medium size samples. Several real examples are also addressed.     

A heuristic procedure from determining manufacturing families from design-based grouping for flexible manufacturing systems

This paper outlines an external-criterion-based procedure for clustering a set of parts into families. A design-based configuration of families is initially chosen; the procedure then reallocates the parts among families to reflect identical processing and tooling requirements. A criterion entitled “overall dissimilarity coefficient” (ODC) has been defined and employed to facilitate the transfer of parts between families, and an algorithm is developed to carry out the reallocation. A set of thirty parts has been used to illustrate the procedure.     

A constraint programming approach to tool allocation and production scheduling in flexible manufacturing systems

This paper presents a constraint programming (CP) methodology to deal with the scheduling of flexible manufacturing systems (FMSs). The proposed approach, which consists of both a model and a search strategy, handles several features found in industrial environments, such as limitations on number of tools in the system, lifetime of tools, as well as tool magazine capacity of machines. In addition, it tackles the problem in a integrated way by considering tool planning and allocation, machine assignment, part routing, and task timing decisions altogether in the approach. The formulation, which is able to take into account a variety of objective functions, has been successfully applied to the solution of test problems of various sizes and degrees of difficulty.     

A concise review of flexible manufacturing systems and FMS literature

The widespread popularity of Flexible Manufacturing Systems (FMS) has resulted in a prolific bibliography of literature describing several frameworks for analysis, planning and control of this automated mode of production. In this paper we review literature and discuss both the major characteristics of FMS and the contemporary decision support systems that have emerged to address the planning and control problems inherent in FMS.