Manufacturing cost modelling for concurrent product development

This research work aims to develop an intelligent knowledge-based system that accomplishes an environment to assist inexperienced users to estimate the manufacturing cost modelling of a product at the conceptual design stage of the product life cycle. Therefore, a quicker response to customers’ expectations is generated. This paper discusses the development process of the proposed system for cost modelling of machining processes. It embodies a CAD solid modelling system, user interface, material selection, process/machine selection, and cost estimation techniques. The main function of the system, besides estimating the product cost, is to generate initial process planning includes generation and selection of machining processes, their sequence and their machining parameters. Therefore, the developed system differs from conventional product cost estimating systems, in that it is structured to support concurrent engineering. Manufacturing knowledge is represented by hybrid knowledge representation techniques, such as production rules, frames and object oriented. To handle the uncertainty in cost estimation model that cannot be addressed by traditional analytical methods, a fuzzy logic-based knowledge representation is implemented in the developed system. Based on the analysis of product life cycle, the estimated cost included material, processing, machine set-up and non-productive costs. A case study is discussed and demonstrated to validate the proposed system.     

A concurrent engineering constraint-based system

This research article demonstrates the use of constraint networks for modelling the knowledge which is necessary for concurrent product and process design. A knowledge-based constraint network system has been developed to maintain design consistency and to support the selection of appropriate manufacturing processes according to pre-defined constraints. A number of constraints related to existing manufacturing facilities and expertise are formulated and modelled using the rules of the knowledge-based toolkit. These constraints are implemented to identify the appropriate machining processes and to show the feasibility of a product's design as it progresses and before making the final prototype. The combination of design and manufacturing constraints enables designers to examine whether the designed part can be manufactured with the available manufacturing facilities.     

Extraction of geometric characteristics for manufacturability assessment

One of the advantages of feature-based design is that it provides data which are defined as parameters of features in readily available forms for tasks from design through manufacturing. It can thus facilitate the integration of CAD and CAM. However, not all design features are features required in down stream applications and not all parameters or data can be predefined in the features. One of the significant examples is property that is formed by feature interactions. For example, the interaction of a positive feature and a negative feature induces a wall thickness change that might cause defects in a part. Therefore, the identification of the wall thickness change by detecting the feature interaction is required in the moldability assessment.The work presented in this paper deals with the extraction of geometric characteristics in feature-based design for manufacturability assessment. We focus on the manufacturability assessment of discrete parts with emphasis on a net shape process—injection molding. The definition, derivation and representation of the spatial relationships between features are described. The geometric characteristics formed by feature interactions are generalized as significant items, such as “depth”, “thickness”, “height” etc. based on the generalization of feature shapes. Reasoning on feature interactions and extraction of geometric characteristics is treated as a refinement procedure. High-level spatial relationships—“is_in”, “adjacent_to” and “coplanar” as well as their geometric details are first derived. The significant items formed from feature interactions are then computed based on the detailed spatial relationships. This work was implemented in a computer-aided concurrent product and process development environment to support molding product design assessment.     

An implementation of the object-oriented concurrent programming language SINA

SINA is an object-oriented language for distributed and concurrent programming. The primary focus of this paper is on the object-oriented concurrent programming mechanisms of SINA and their implementation. This paper presents the SINA constructs for concurrent programming and inter-object communication, some illustrative examples and a message-based implementation model for SINA that we have used in our current implementation.     

An object-oriented simulation-optimization interface

Progress in the field of structural optimization naturally leads to an increasing number of structural models and optimization algorithms that need to be considered for design. Software architecture is of central importance in the ability to account for the complex links tying new structural models and optimizers. An object-oriented programming pattern for interfacing simulation and optimization codes is described in this article. The concepts of optimization variable, criteria, optimizers and simulation environment are the building blocks of the pattern. The resulting interface is logical, flexible and extensive. It encompasses constrained single or multiple objective formulations with continuous, discrete or mixed design variables. Applications are given for composite laminate design.     

The distributed programming language SR—Mechanisms,design and implementation

SR is a new language for programming software containing many processes that execute in parallel. The language allows an entire software system that controls a potentially large collection of processors to be programmed as an integrated set of software modules. The key language mechanisms are resources, operations and input statements. The language supports separate compilation, type abstraction, and dynamic communication links; it also contains novel treatments of arrays and procedures. This paper gives an overview of the language mechanisms, discusses some of the major design decisions and describes one implementation.     

Automated object-oriented reusable component identification

An automated tool to assist in the understanding of legacy code can be useful both in the areas of software reuse and software maintenance. Most previous work in this area has concentrated on functionally-oriented code. Whereas object-oriented code has been shown to be inherently more reusable than functionally-oriented code, in many cases the eventual reuse of the object-oriented code was not considered during development. This paper describes an approach that makes preparing existing object-oriented code for reuse easier and more quantifiable. This problem includes two primary sub-problems: understanding the function of components, and applying an appropriate set of metrics to the components to quantify reusability.The research described in this paper addresses an approach to the automated understanding of object-oriented code. A knowledge-based system that implements the approach is described. This paper also briefly discusses the formulation of reusability metrics for object-oriented code.     

Environment for rapidly creating interactive design tools

The Garnet toolkit was specifically designed to make highly interactive graphical programs easier to design and implement. Visual, interactive, user-interface design tools clearly fall into this category. At this point, we have used the Garnet toolkit to create three different interactive design tools: Gilt, a simple interface builder for laying out widgets; Lapidary, a sophisticated design tool for constructing application-specific graphics and custom widgets; and C32, a spreadsheet interface to constraints. The features of the Garnet toolkit that made these easier to create include use of a prototype-instance object system instead of the usual class-instance model, integration of constraints with the object system, graphics model that supports automatic graphical update and saving to disk of on-screen objects, separation of specifying the graphics of objects from their behavior, automatic layout of graphical objects in a variety of styles, and a widget set that supports such commonly used operations as selection, moving and growing objects, and displaying and setting their properties.     

A decision-making framework model for design and manufacturing of mechanical transmission system development

Knowledge-based systems are proving to be a powerful tool with great potential for developing intelligent design support environments to improve quality of products and reduce product development costs by eliminating or minimizing many of the trial-and-error iterations involved in product development. This article describes an approach towards the development of intelligent design support environments for mechanical transmission systems, along with implementation details of a distributed knowledge-based gearing design and manufacturing system that is deployed over the Internet. The system embodies the various tasks of the design process, with modules that address: performance evaluation, process optimization, manufacturability analysis, and provides reasoning and decision-making capabilities for reducing the time between gear tooth creation, detailed design and final production. This methodology is highly desirable in that it is able to simulate real working conditions, evaluate and optimize the design effectively, prevent designers from time-consuming iterations and reduce long and expensive test phases.     

A PDES/STEP-based model and system for concurrent integrated design and assembly planning

Product data exchange and interfacing between different CAD/CAM systems are of great importance to the development of concurrent integrated design environments and computer integrated manufacturing systems. This paper presents a STEP-based method and system for concurrent integrated design and assembly planning. An integrated object model for mechanical systems and assemblies is first defined by a hierarchy of structure, geometry and feature. The structure is represented as a component-connector or joint multi-level graph with both hierarchical functional and assembly relations. These hierarchical relation models are then used for uniformly describing their causal relations both for assembly level and feature based single part level. The generic product assembly model is organized according to STEP, using mostly the entities of integrated resources and partly self-defined entities, which are necessary for design and assembly planning. Based on the generic product assembly model, STEP-based strategies and agent concepts are used for agent-based concurrent integration of design and assembly planning. A prototype system, consisting of a CAD system, a product modeling system, an assembly planning system, and an assembly evaluation system is developed, in which product data can be exchanged between these subsystems. Details about the implementation of the system are addressed. The integrated design and assembly planning system can support the introduction of a new product. The results of assembly planning are feedback to the stage of assembly design to improve on the design. A case study is carried out for assembly-oriented design of a gearbox, to illustrate the proposed approach and to validate the developed system.     

An interpretation of typed OOP in a language with state

In this paper we give semantics toLoop, an expressive typed object-oriented programming language with updatable instance variables.Loop has a rich type system that allows for the typing of methods operating over an open-ended self type. We prove the type system given is sound;i.e., well-typed programs do not experience message not understood errors. The semantics ofLoop is given by a translation into a state-based language,Soop, that contains reference cells, records, and a form of F-bounded polymorphic type.Partially supported by NSF grant CCR-9109070Partially supported by AFOSR grant F49620-93-1-0169     

Paradigm shift: unified and associative feature-based concurrent and collaborative engineering

With widely used concurrent and collaborative engineering technologies, the validity and consistency of product information become important. In order to establish the state of the art, this paper reviews emerging concurrent and collaborative engineering approaches and emphasizes on the integration of different application systems across product life cycle management (PLM) stages. It is revealed that checking product information validity is difficult for the current computer-aided systems because engineering intent is at best partially represented in product models. It is also not easy to maintain the consistency among related product models because information associations are not established. The purpose of this review is to identify and analyze research issues with respect to information integration and sharing for future concurrent and collaborative engineering. A new paradigm of research from the angle of feature unification and association for product modeling and manufacturing is subsequently proposed.     

基于特征和知识的注塑模CAD/CAE集成化研究

重点讨论了利用特征造型技术和人工智能技术进行CAD／CAE集成的方法,并对系统集成的关键技术进行了研究。在对产品建模过程中,针对问题的不同特点采用不同的方法对知识进行提取和推理,最终目的是提高注塑模设计的自动化程度,实现设计－分析的自适应。     

The concept and implementation of skeletal plans

A new method for automated planning, refinement of skeletal plans, has been developed for the problem of experiment design in the domain of molecular biology. The method resulted from a study of the problem-solving behavior of scientists which showed that design usually consisted of look-up of abstracted plans followed by hierarchical plan-step refinement. The skeletal plan method has been implemented through two generations of problem-solving systems, the second generation involving a synthesis with the metaplanning approach of Stefik.     

From patterns to frameworks to parallel programs

Object-oriented programming, design patterns, and frameworks are abstraction techniques that have been used to reduce the complexity of sequential programming. This paper describes our approach of applying these three techniques to the more difficult parallel programming domain. The Parallel Design Patterns (PDP) process, the basis of the CO₂P₃S parallel programming system, combines these techniques in a layered development model. The result is a new approach to parallel programming that addresses correctness and openness in a unique way. At the topmost development layer, a customized framework is generated from a design pattern specification of the parallel structure of the program. This framework encapsulates all of the structural details of the pattern, including communication and synchronization, to prevent programmer errors and ensure correctness. Lower layers are used only for performance tuning to make the code as efficient as necessary. This paper describes CO₂P₃S, based on the PDP process, and demonstrates it using an example application. We also provide results from a usability study of CO₂P₃S.     

Issues in the design of a parallel object-oriented language

This paper discusses the considerations that have played a role in the design of the language POOL2. This language integrates the structuring techniques of object-oriented programming with mechanisms for expressing parallelism. We introduce the basic principles of object-oriented programming and its significance for program development methodologies. Several approaches for integrating objects and parallelism are compared and arguments for the choices made in POOL2 are presented. We also explain why inheritance is not yet included in POOL2. A brief overview of the research in formal aspects of POOL is given. Finally we indicate some directions for future developments.     

A software framework for data analysis

The open-source Java software framework JStatCom is presented which supports the development of rich desktop clients for data analysis in a rather general way. The concept is to solve all recurring tasks with the help of reusable components and to enable rapid application development by adopting a standards based approach which is readily supported by existing programming tools. Furthermore, JStatCom allows to call external procedures from within Java that are written in other languages, for example Gauss, Ox or Matlab. This way it is possible to reuse an already existing code base for numerical routines written in domain-specific programming languages and to link them with the Java world. A reference application for JStatCom is the econometric software package JMulTi, which will shortly be introduced.