Survey of research in the design and control of automated guided vehicle systems

Automated guided vehicles (AGVs) are used for the internal and external transport of materials. Traditionally, AGVs were mostly used at manufacturing systems. Currently, AGVs are also used for repeating transportation tasks in other areas, such as warehouses, container terminals and external (underground) transportation systems. This paper discusses literature related to design and control issues of AGV systems at manufacturing, distribution, transshipment and transportation systems. It is concluded that most models can be applied for design problems at manufacturing centres. Some of these models and new models already proved to be successful in large AGV systems. In fact, new analytical and simulation models need to be developed for large AGV systems to overcome large computation times, NP-completeness, congestion, deadlocks and delays in the system and finite planning horizons. We specify more specific research perspectives in the design and control of AGV systems in distribution, transshipment and transportation systems.     

Fuzzy optimization approach to component selection of fault-tolerant software system

In developing software systems, a manager’s goal is to design software using limited resources and meet the user requirements. One of the important user requirements concerns the reliability of the software. The decision to choose the right software modules (components) becomes extremely difficult because of the number of parameters to be considered while making the decision. If suitable components are not available, then the decision process is further complicated with build versus buy decisions. In this paper, we have formulated a fuzzy multi-objective approach to optimal decision “build-or-buy” for component selection for a fault-tolerant modular software system under the consensus recovery block scheme. A joint optimization model is formulated where the two objectives are maximization of system reliability and minimization of the system cost with a constraint on delivery time. An example of developing a retail system for small-and-medium-size enterprises is used to illustrate the proposed methodology.     

Fuzzy systems based on component software

This paper describes hierarchical modeling of fuzzy logic concepts that has been used within the recently developed model of intelligent systems, called OBOA. The model is based on a multilevel, hierarchical, general object-oriented approach. Current methods and software design and development tools for intelligent systems are usually difficult to extend, and it is not easy to reuse their components in developing intelligent systems. The OBOA model tries to reduce these deficiencies. The model starts with a well-founded software engineering principle, making clear distinction between generic, low-level intelligent software components, and domain-dependent, high-level components of an intelligent system. This paper concentrates on modeling and implementation of fuzzy logic concepts within the hierarchical levels of the OBOA model. The fuzzy components described are extensible and adjustable. As an illustration of how these components are used in practice, a practical design example from the domain of medical diagnosis is shown. The paper also suggests some steps towards future design of fuzzy components and tools for intelligent systems.     

Computer-aided Modelling of Decision-support Systems

Information systems have become increasingly complex over recent years, underscoring the challenge of designing systems which will provide the different functions in an organization with the information necessary for effective decision-making. With rapidly developing computer technology, it is natural that information systems evolve in a manner which is greatly dependent on computing hardware and software. Yet, there has been little development in the techniques of systems analysis and design to handle new and less well-understood functions which are of increasing interest.This paper demonstrates an application of structural modelling concepts to decision-support system synthesis. With the aid of the computer, structural modelling serves as an effective tool for: (1) partitioning a system into a set of subsystems; (2) specifying subsystems sufficiently to permit separate testing before total system tests; (3) eliminating redundant control information flow; and (4) facilitating decision-maker and system-analyst coordination and participation in the design process.     

Robots,CAM and O.R.

Microelectronics have greatly influenced the nature of manufacturing technology and systems. New factories make growing use of microcomputers and microprocessors in robots, C.N.C. machine tools and flexible manufacturing systems. The result is an increasing trend towards fully integrated computer-based manufacturing systems. As a consequence, O.R. software has a newer, more direct role in the modern factory than ever before. Fully integrated CAM systems are implemented by multi-disciplinary teams of engineers and management scientists. The O.R. practitioner can make a major contribution, for example in layout optimisation and plant simulations.     

Long term capacity decisions in uncertain markets for advanced manufacturing systems incorporating scope economies

By examining the literature in the field of manufacturing flexibility many researchers have located several form of flexibility by distinguishing them into strategic and operational flexibility forms. Furthermore, many measures and design methods have been proposed for flexible manufacturing systems. Surely scope economies are one of the most important strategic form of flexibility in manufacturing systems and their strategic impact has been acknowledged by the very beginning of the flexible manufacturing era. However, despite several researches are available to address scope economies measurement and design methodologies, very few researches investigate their economic convenience in front of dedicated manufacturing systems depending on the competitive market conditions.This paper proposes a theoretical model whose main aim is the general understanding of the convenience conditions of scope economies-based manufacturing systems. The results of the theoretical model are very interesting, because they locate market conditions that make scope economies manufacturing systems less profitable than dedicated manufacturing ones; moreover, the proposed model sets some general criteria to guide the entrepreneur in making right investment decision regarding this kind of manufacturing investments. Such results can explain the reason of many failures of flexible manufacturing systems and it suggests the use of this kind of approach to investigate other flexibility forms of manufacturing systems. The ultimate goal of this research is the construction of a Decision Support System for supporting the entrepreneur in making decision on Advanced Manufacturing Systems investment decisions.     

Application of fuzzy compromise solution method for fit concept selection

The modern manufacturing environment is highly turbulent so as to satisfy the dynamic needs of customers’. To enable the achievement of competitiveness in this complex business environment, newer manufacturing strategies have been introduced for enabling waste elimination and enhancing flexibility and responsiveness of systems. Fit manufacturing is a competitive manufacturing paradigm which includes lean and agile systems coupled with sustainable benefits. This article presents a study in which the concept selection in fit environment was formulated as Multi Criteria Decision Making (MCDM) problem and solved using fuzzy based compromise solution method, Vlsekriterijumska Optimizacija I Kompromisno Resenje (VIKOR). The selected concept design of automotive component was subjected to implementation in the case organisation.     

Some open problems in the design and use of modern production systems

During the past two decades, manufacturing systems have moved towards automation, integration and modularity. These trends will certainly continue in the future due to the constraints of the market and to evolution of resources and worker requirements. As a consequence, the design and use of manufacturing systems are increasingly expensive. Numerous methods and tools have been developed to face up to this situation, but some complementary aids could be provided for designers and manufacturing engineers. The goal of this paper is to present important open problems whose solutions could certainly significantly improve the design and use of modern production systems.     

Metaheuristics for a Flexible Assembly System Design Problem

Flexibility has become an important priority in the formulation and implementation of manufacturing strategies. This in turn has opened up a new class of design problems for such systems. Flexible assembly systems (FAS), consisting of a variety of processors and operations, provide the opportunity for improving product manufacturing flexibility, hence gaining competitive advantages. This paper considers a particular design decision problem for FAS. A matrix-based, polynomial-time lower bound algorithm is presented. Simulated annealing and tabu search metaheuristics are formulated to address the problems. Computational experience with these metaheuristics is reported.     

SKIM: a Simulation Sketchpad for Plant Design

This paper describes the development of a simulation sketchpad for use by engineers who design quasi-continuous manufacturing plants. The concept is of a simple data-driven simulation package which is based on a very small number of building blocks and yet is powerful enough for proper use. The paper defines quasi-continuous manufacturing, discusses the ideas of the sketchpad and describes their implementation in prototype software known as SKIM. Finally, the paper reflects on the development of SKIM and suggests improvements to the prototype which have validity for data-driven software in general.     

The Role of Queueing Network Models in Performance Evaluation of Manufacturing Systems

Models of manufacturing systems are used for performance evaluation during the design stage, allowing system designers to fine tune their system before proceeding to the implementation phase. In recent years, several queueing network model implementations have been used in the performance evaluation of manufacturing systems. Although these implementations incorporate many of the recent advances in queueing theory, we find significant departures from simulation results when applied to realistic manufacturing systems, even for those within the stated domain of assumptions and limitations of these implementations. While utilization estimates are usually quite accurate, the flowtime and work in process results are not as robust.     

Bank-office Process Management in the Financial Services: a Simulation Approach Using a Model Generator

For the last ten years or so, developments in simulation software and methodology have been focused in two areas: (1) automating the model-building process; and (2) interfacing with other techniques and systems. That both academic and commercial research continues to be carried out in these areas is evidence of the continued popularity of the simulation technique. The most popular application areas where simulation modelling is used include manufacturing (engineering and process), warehousing and communications; not surprisingly, research and developments have therefore been concentrated in these areas. This paper describes the development of a simulation model generator for a different application area, that of clerical office processing of paper and documents for financial service companies. It outlines the reasons why there is a need for such a model generator and discusses the initial design requirements. The paper goes on to detail the developments and re-defined criteria required as the model generator brief changes as a result of practical applications.     

Rapid and modular prototyping-based Petri nets and distributed simulation for manufacturing systems

This paper presents an approach to simulate and implement by stepwise refinement the whole manufacturing system (MS) by means of distributed simulation. This approach is based on the use of different classes of Petri nets to model different levels of a manufacturing system. Furthermore these classes may match the abstraction levels of a high-level Petri net used to model the MS. Each level can be simulated on a processor or a cluster of processors which can communicate between themselves using a network. The main contribution is to give the opportunity to combine simulation, performance evaluation and emulation. The emulation means that a part of the system can be run in real time while the other part is simulated. Moreover based on the abstraction levels of high-level Petri nets, subsystems can be integrated step-by-step from the design stage to the implementation one, allowing inter-changeability between simulated components and real-time physical systems. This approach is achieved by defining a simulation engine which involves a local simulator, an emulator and an interface to the physical process. Criteria are defined to use an emulator or a local control software for a physical process as a logical process for the conservative distributed simulation.     

Problems of Stability of Dynamical Systems and Computer Algebra

Examples of problems of motion stability solved with the help of computer algebra systems (CAS) are presented. The authors have experience in developing and applying problem-oriented systems of symbolic computations and software packages for solving problems of dynamics of multi-body systems. The algorithms under consideration are implemented (completely or partly) with the aid of up-to-date CAS. They are intended for inclusion in the ``Stability' package of symbolic computation. Bibliography: 6 titles.     

Infinitesimal perturbation analysis for second derivative estimation and design of manufacturing flow controllers

A simulation-based numerical technique for the design of near-optimal manufacturing flow controllers for unreliable flexible manufacturing systems uses quadratic approximations of the value functions that characterize the optimal policy and employs stochastic optimization to design the key coefficients of the quadratic approximations. First and second derivative estimates that drive the optimization algorithm are obtained from a single sample path of the system via infinitesimal perturbation analysis (IPA). Extensive computational experience is reported for one, two, and three-part-type production systems. The relative performance of first-order and second-order stochastic optimization algorithms is investigated. The computational efficiency of these algorithms is finally compared to conventional controller design algorithms based on state-space discretization and successive approximation.This research was supported by the National Science Foundation, Grant No. DDM-89-14277 and DDM-9215368.     

Intermediate Generality Simulation Software for Production

Simulation has long been a valuable tool in the field of production. With the current and anticipated developments in computing equipment, there is a demand for simulation software, which can be used by managers to investigate specific classes of problems. The O.R. profession should involve itself in the identification of suitable areas and the development of appropriate software. Two such areas where simulation software is being developed are discussed: production planning in a batch environment and the investigation of advanced manufacturing systems.     

Combined DEMATEL technique with hybrid MCDM methods for creating the aspired intelligent global manufacturing & logistics systems

The concept of globalization has been prosperous in the past decades while manufacturing as well as logistics have already become one of the most significant issues in the globalization era. However, while modern globalized firms are leveraging both global manufacturing resources as well as logistics systems for pursuing higher quality, lower cost as well as product differentiation, how to evaluate, selecting an appropriate global manufacturing strategy by considering issues from both aspects of global manufacturing as well as logistics has become one of the most critical and difficult issues. Moreover, how the chosen intertwined global manufacturing as well as logistics system is to be optimized so that the aspired level of the global manufacturing system can be achieved have few been addressed. Thus, this research aims to resolve the above mentioned global manufacturing and logistics strategy selection as well as system reconfiguration issue. A Decision Making Trial and Evaluation Laboratory (DEMATEL) technique based novel multiple criteria decision making (MCDM) method with Analytic Network Process (ANP), Grey Relational Analysis (GRA) as well as VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) will be proposed for selecting and re-configuring the aspired global manufacturing and logistics system. An empirical study based on the global manufacturing and logistics system design of a semiconductor company will be provided for verifying the effectiveness of this proposed methodology.     

Architecture of manufacturing scheduling systems: Literature review and an integrated proposal

This paper deals with the development of customised and realistic manufacturing scheduling systems. More specifically, we focus onto a key element that may help driving their efficient design and implementation: i.e., the set of building blocks that should include a generic scheduling system and its interconnections, a set collectively known as the architecture of a system. To do so, we first analyse existing contributions on the topic together with papers describing different functional requirements of scheduling systems. These contributions are then discussed and classified, and a modular architecture for manufacturing scheduling systems is proposed. This proposal updates, extends and refines the well-known architecture proposed earlier by Pinedo and Yen’s [Pinedo, M.L., Yen, B.P.-C., 1997. On the design and development of object-oriented scheduling systems. Annals of Operations Research 70 (1), 359–378], and serves to integrate the different requirements identified in the literature review.     

Recent Developments in Simulation Modelling

Current trends in simulation software development are towards the automation of the modelling process. Some systems provide a method of specifying the problem so that a computer program can be automatically generated. Other systems provide a generic framework for a particular class of modelling problem that can be input as data to the system. Examples of the latter are flexible manufacturing systems simulations. Most current developments are colour-graphics-aided in one form or another. Computer advances in hardware and software are emerging through better user interfaces, more power and lower costs. The major benefit is an increasing customer involvement in the modelling process. An overview of these developments and future directions are given in this paper.