A distributed task planning system for computer-integrated manufacturing systems

A formal mathematical framework for a distributed task planning method suitable for computerintegrated manufacturing systems is proposed. All pertinent algorithms are derived. A detailed timing analysis associated with primitive actions and activities (complex tasks) execution is presented. A formal language is designed for event tracking and error specification. Based on the derived language, an error recovery mechanism (automaton) is proposed. A case study demonstrates the applicability of the presented method with and without error occurrences.Dr Kokinaki is currently Science and Engineering Research Centre, De Montfort University, UK.     

An integrated methodology for fixture design

In this paper, a methodology to perform fixture design as an integrated aspect of process planning is proposed. A three-phase methodology for the fixture design activity has been developed. The three phases include predesign analysis (phase I), functional analysis (phase II), and productivity improvement (phase III). In phase I, the product design information is studied, and initial fixture design aspects are developed. In phase II, the clamping and location aspects of fixture design are addressed for the given initial process sequence and product design information. Phase III involves studying ways to increase the productivity including using simultaneous machining approaches, multiclustering, use of specialized jigs, etc.     

An information system for computer-integrated manufacturing systems

One of the main problems when implementing the computer-integrated manufacturing (CIM) concept concerns information integration. In order to support information integration, an information system provided with suitable data models is required. In this paper an information system is presented, which fulfils the requirements for an appropriate information management in CIM. For this purpose, an EXPRESS-oriented information system has been built on top of a commercial relational DBMS. The conceptual model of the information is built in EXPRESS and then parsed and translated to the corresponding relational constructs. A data access interface has been implemented which allows EXPRESS-oriented data manipulation. The information system was developed inside ESPRIT project No. 2202 CIM-PLATO “CIM System Planning Toolbox” to integrate the information used by the tools developed for flexible manufacturing system planning.     

Conception and Implementation of an Object Request Broker for the Integration of the Process Level in Manufacturing Systems

In order to be able to react quickly to altering production states, planning tools such as Manufacturing Resource Planning and Enterprise Resource Planning heavily rely on up to date information about the process itself. Thus, access to process level data is one of the most important issues within the production industry. However, the process level lacks support for open, connective communication systems as the number of incompatible fieldbus systems shows. Current solutions, e.g., OLE for Process Control, only focus on a unified interface to the process level, but do not allow to access the functionality of a field device directly. The approach presented in this paper introduces FIMO, the Fieldbus Messaging Object Request Broker, to be deployed in field devices and utilizing the existing fieldbus protocols. With the use of FIMO, devices connected to a fieldbus can be seamlessly integrated in the whole manufacturing hierarchy. The paper gives a brief overview of thestate of the art for accessing process level data. Then, the FIMO architecture is presented in detail including its core services and the mapping of the communication services to the underlying fieldbus system.     

Manufacturing system application of a knowledge based simulation

The flexibility in a modern manufacturing facility introduces complexity to the decision making. The requirement for a real time control mechanism results in a need for an on-line simulation system that can simulate the complicated scheduling, routing and similar decisions required by the system.

This paper describes a knowledge-based simulation and control system written in PROLOG. This system is composed of four parts: a static data base, a dynamic database, a modeling knowledge part, and a simulation driver. The simulator contains the actual control mechanism of the physical system and can be removed from the system in order to simulate it.

The manufacturing system under investigation is a combination of flexible manufacturing cells that feed an automated assembly station. The knowledge-based simulation helps to develp and understand control mechanisms for that system, which can later be implemented in the physical system as the controller.     

An object-oriented bill of materials system for dynamic product management

In this paper, the bill of materials (BOM) system is defined as the central hub of a general product data management (PDM) system that provides essential data for running a manufacturing system to produce products. Information that is relevant to products and their components is defined in the BOM. The information is critically related to data from product design, manufacturing planning, production management, procurement, inventory control, and accounting within a company. A conventional BOM structure (or product configuration), which manages data only in a stand-alone relational database management style, cannot satisfy the needs requested by all departments within a company. A BOM should relate to and communicate with other domains of the information system. In this research, a newly designed BOM system uses the object-oriented programming (OOP) concept to represent product information. The object-oriented BOM (OOBOM) system can capture and encapsulate data that will simultaneously serve the information needs of various departments. In order to manage product data dynamically, the system provides several interfaces for easy data access and manipulation. The linkage between BOM and its corresponding CAD/CAM system is enabled through the X-window manager: thus an integrated PDM environment is developed. This product management approach improves the consistency and efficiency of product data representation.     

A fuzzy reasoning based diagnosis system for X control charts

This paper describes a new diagnosis system, which is based on fuzzy reasoning to monitor the performance of a discrete manufacturing process and to justify the possible causes. The diagnosis system consists chiefly of a knowledge bank and a reasoning mechanism. The knowledge bank provides knowledge of the membership functions of unnatural symptoms that are described by Nelson's rules on X control charts and knowledge of cause-symptom relations. We develop an approach called maximal similarity method (MSM) for knowledge acquisition to construct the fuzzy cause-symptom relation matrix. Through the knowledge bank, the diagnosis system can first determine the degrees of an observation fitting each unnatural symptom. Then, using the fuzzy cause-symptom relation matrix, we can diagnose the causes of process instability. In conclusion we provide a numerical example to illustrate the system.     

交互式基于范例的推理及应用研究

1.引言近几年来,研究人员一直在致力于研究和解决基于范例推理(Case-based reasoning,CBR)的理论和应用课题,如更为有效的范例表示、索引、检索和修改方法,范例库的创建及维护方法,将CBR与其它人工智能技术集成等。一般说来,传统的CBR是以静态的方式求解问题的。范例是处于一种被动、等待被检索的状态,不能根据所要求解的问题及环境的变化,通过和用户的交互调整范例的内容、结构进行问题的求解。另一方面,在大部分传统的CBR系统中,都是要求用户一开始就要向系统输入一个所要求解的问题的完整描述,然后才开始求解。这就要求用户事先必须确定与问题求解有关的特征,并具有较为详尽的领域知识。这在实际中往往是难以做到的。再者,从应用的角度看,传     

A -based layout design for gratings allocation

In the design process of gratings, the grating layout design is the most important activity influencing manufacturing cost. In the grating layout design, the key to saving manufacturing cost is to find a design with a minimal number of cutting operations. This paper presents an application of the A^* algorithm in grating layout design. The design problem is represented as the space search problem of design alternatives. A^* explores the feasible alternatives within the space, until an optimal solution is obtained.     

An expert system for engine fault diagnosis: development and application

The mass production and wider use of automobiles and the incorporation of complex electronic technologies all indicate that the control of faults should be given an integral part of engine design and usage. Today, artificial intelligence (AI) technology is widely suggested for systematic diagnosis of faults where the amount of well-defined diagnosis knowledge is vast and the sequence of steps required to identify the fault is very long. This article describes on an expert system application for automotive engines. A new prototype named EXEDS (expert engine diagnosis system) has been developed using KnowledgePro, an expert system development tool, and run on a PC. The purpose of the prototype is to assist auto mechanics in fault diagnosis of engines by providing systematic and step-by-step analysis of failure symptoms and offering maintenance or service advice. The result of this development is expected to introduce a systematic and intelligent method in engine diagnosis and mai ntenance environments.     

Decision support and control for large-scale complex systems

The technical and social systems of the present day are ever more large, complex and complicated objects. Their models are characterized by numerous state and control variables, time delays, and different time constants. Also they show constraints in their information infrastructure and risk sensitivity aspects. Such systems are called large-scale complex systems (LSS). Hierarchical approach which has been for several decades one of the most utilized methodologies for controlling large-scale systems has evolved in recent years toward more collaborative schemes. When human intervention is necessary, decision support systems (DSS) can represent a solution. A DSS is an adaptive and evolving information system meant to implement several of the functions of a human support team that would otherwise be needed to help the decision-maker to overcome his/her limits and constraints he/she may face when approaching decision problems that count in the organization. This paper aims at reviewing several aspects concerning the utilization and technology of DSS in the context of LSS control. Particular emphasis is put on real-time DSS and multi-participant (group) DSS which support collaborative work. Several advanced solutions such as mixed knowledge systems, that combine numerical methods with AI-based tools, and the prospects of using Ambient intelligence (AmI) concepts in DSS construction are described.     

A recommender mechanism based on case-based reasoning

Case-based reasoning (CBR) algorithm is particularly suitable for solving ill-defined and unstructured decision-making problems in many different areas. The traditional CBR algorithm, however, is inappropriate to deal with complicated problems and therefore needs to be further revised. This study thus proposes a next-generation CBR (GCBR) model and algorithm. GCBR presents as a new problem-solving paradigm that is a case-based recommender mechanism for assisting decision making. GCBR can resolve decision-making problems by using hierarchical criteria architecture (HCA) problem representation which involves multiple decision objectives on each level of hierarchical, multiple-level decision criteria, thereby enables decision makers to identify problems more precisely. Additionally, the proposed GCBR can also provide decision makers with series of cases in support of these multiple decision-making stages. GCBR furthermore employs a genetic algorithm in its implementation in order to reduce the effort involved in case evaluation. This study found experimentally that using GCBR for making travel-planning recommendations involved approximately 80% effort than traditional CBR, and therefore concluded that GCBR should be the next generation of case-based reasoning algorithms and can be applied to actual case-based recommender mechanism implementation.     

Developing control and integration software for flexible manufacturing systems

The slow growth of computer-integrated manufacturing is attributed to the complexity of designing and implementing their control and integration software. This article expands on a methodology for designing and implementing this software that was introduced in [16]. The goal of this methodology is to build flexible and resuable control and integration software for computer-integrated manufacturing systems. It hinges upon the concepts of software/hardware components, their assemblages, a distributed common language environment, formal models, and generic controllers. Major sources of flexibility are obtained by decoupling process plan models from the model of the factory floor and by using a generic controller. Reusability is achieved by building selfcontained software/hardware components with general, possibly parametrized, interfaces. The interplay between simulated and actual hardware internals of software/hardware components is used as the basis of a testing strategy that performs off-line simulation followed by on-line testing.The methodology has been applied in designing and implementing the control and integration software of an actual Prismatic Machining Cell. The article also reports on the details of this implementation.The names of the authors appear in alphabetical order.     

A microcomputer-based knowledge system for CAD software selection

This paper documents a prototype knowledge system which has been developed to select the most appropriate CAD software based on the user's requirements and preferences.     

对象的类比推理研究

本文首先提出对象与对象抽象、规则序与规则映射的理论,为对象的类比推理奠定了一定的基础,在此基础上,建造了对象类比推理模型ＯＡＭ．     

A review of methods for automatic understanding of natural language mathematical problems

This article addresses the problem of understanding mathematics described in natural language. Research in this area dates back to early 1960s. Several systems have so far been proposed to involve machines to solve mathematical problems of various domains like algebra, geometry, physics, mechanics, etc. This correspondence provides a state of the art technical review of these systems and approaches proposed by different research groups. A unified architecture that has been used in most of these approaches is identified and differences among the systems are highlighted. Significant achievements of each method are pointed out. Major strengths and weaknesses of the approaches are also discussed. Finally, present efforts and future trends in this research area are presented.     

Expert system problem selection: A domain characteristics approach

The first generation of commercial expert systems based on AI technology are now available in the market place. But in the available literature, one can find hardly any material on expert system problem selection. In this paper a number of popular and successful expert systems are analyzed. Domain-dependent and domain-independent problem characteristics have been identified, based on the analysis. To test our contention that these characteristics significantly contribute to the success of expert systems, a questionnaire survey involving a number of expert system developers was conducted. Based on this, a domain characteristic approach for expert system problem selection is presented.     

PolicyUpdater: a system for dynamic access control

PolicyUpdater is a fully-implemented authorisation system that provides policy evaluations as well as dynamic policy updates. These functions are achieved by the use of a logic-based language, , to represent the underlying access control policies, constraints and update propositions. The system performs access control query evaluations and conditional policy updates by translating the language policies to a normal logic program in a form suitable for evaluation using the Stable Model semantics. In this paper, we show the underlying mechanisms that make up the PolicyUpdater system, including the theoretical foundation of its formal language, system structure, implementation issues and performance analysis.