Integrated reverse engineering and rapid prototyping

Reverse engineering is a methodology for constructing CAD models of physical parts by digitizing an existing part, creating a computer model and then using it to manufacture the component. When a digitized part is to be manufactured by means of rapid prototyping machines such as stereolithography apparatus (SLA) and selective laser sintering equipments (SLS), etc., it is not necessary to construct the CAD model of a digitized part. This will be described by the proposed novel method which can construct STL file (the de facto file format for rapid prototyping machines) directly from digitized part data. Further more, the STL file can even be constructed in a way that significant data reduction can be achieved at the users' discretion.     

Knowledge-based system for rapid prototyping

In recent years it has been noticed that rapid prototyping produces better software products. Research on combining Artificial Intelligence and software engineering has also been conducted for a number of years. A knowledge-based system for rapid prototyping is presented. In the system, the Frame-and-Rule Oriented Requirements Language and a methodology are developed to provide an integrated means of prototyping throughoyt the software life cycle. The particular application domain to be modelled is represented in terms of objects and activities. FRORL, which uses the concept of frames and production systems, describes the problem domain's objects and activities in a natural way. With the support of a knowledge base, a software prototype can be rapidly developed using FRORL. The system has been implemented using Prolog on a VAX-11/780 computer.     

An integrated manufacturing system for rapid tooling based on rapid prototyping

To reduce the time and cost of moulds fabrication, a novel integrated developing and manufacturing system of rapid tooling (RT) based on rapid prototyping (RP) is proposed. The architecture of system which consists of four building blocks: digital prototype, virtual prototype (VP), physical prototype and RT system, is presented. A digital prototype can be established by 3D CAD software packages or reveres engineering technique. A VP is employed to guide in optimization of the mould design and manufacturing process planning. A physical prototype, which is built using RP technology, generally serves as a pattern for producing RT. By integrating these building blocks closely, the system can aid effectively in mould design, analysis, prototyping, simulating, and manufacturing process development. Three typical cases are discussed in detail to illustrate the application of the system. It has been shown from a number of case studies that the system has a high potential to reduce further the cycle and cost of die development while minimizing error introduction. As a result, the integrated system provides a feasible and useful tool for companies to speed up their product development.     

Expert system-based selection of the preferred direction of build for rapid prototyping processes

Current commercial rapid prototyping technologies are based on a layered additive process to build parts. The layer-based process results in a stairstepping effect, which can be apparent on curved and sloped surfaces. The selection of the build orientation, whether based on experience, trial and error, or not even considered, is one critical factor that affects the quality of the surface finish. Furthermore, it influences other important aspects, such as the build time and the amount of support structure needed. The authors propose an expert system tool that considers the various parameters that affect the production of the prototype and interacts with the user to recommend the best direction to build. The recommendation is based both on the user's input and on a decision matrix based on the result of interviews with experts, which is implemented within the expert system. If an optimal orientation is not possible, the tool helps the user to select an acceptable build direction. The expert system can also draw attention to issues such as trapped volumes, which can be detrimental to the build process. It helps to reduce the design time, to automate the build process and to minimize the cost of the prototype. The results of this work form a base for ongoing research to complete a tool that considers all major issues for a preferred orientation.     

Interfacing geometric model data with rapid prototyping systems

The direct slicing of CAD models created in CADDS V to generate geometric data for rapid prototyping using fused feposition modeling technique (FDM) is presented in this paper. The report file from an explicit model is accessed for obtaining model data. Algorithms have been developed for determining the volumes of model material as well as support materials. New algorithms have been developed for filling the sheet solid. A simulation module has been developed to verify whether the filling is correctly done. Example of a model is manufactured using this approach is also presented in this paper.     

基于构件技术的快速样机原型的软件框架

以自主研发的HLRESP（honeycomb-like rapid embedded system platform）快速样机系统为基础,提出一种基于构件技术地快速样机原型的软件框架。该软件系统以Eclipse开放平台为基础,并采纳了角色的概念,使之能够支持一定程度上的多人协作开发任务。提出了板级IP（BLIP）的概念,使其在软件系统中的管理方式与FPGA内的IP管理方式一致,简化了软件设计工作。对于IP库的管理,使用了XML（extensible markup language）表示IP（intellectual property）,结合CVS版本控制系统,使得用户能够方便地从IP构件库中获得、配置并集成IP。     

直接金属快速成形中的变形测量系统研制

为了对直接金属快速成形中零件的变形规律进行研究,研制了一个变形测量系统。采用了电感调频式位移传感器,可对零件的变形进行在线或离线测量。通过消息传递机制实现了工作台运动进程与变形数据采集进程之间的通信。采集的数据根据不同分析需求进行输出,可以方便地对零件的变形进行分析研究。     

Concurrent intelligent rapid prototyping environment

Rapid prototyping technology enables rapid production of complex objects directly from a computer-aided design model without involving any tooling or conventional part programming. This has created a new set of problems associated with part design, process planning, support design and value engineering analysis of rapid prototyping parts. In this paper, a methodology for resolving these problems is described, which uses concurrent engineering, distributed blackboard, value engineering, knowledge-based and feature-based technologies. The functionality, design methodology and knowledge representation techniques of a concurrent intelligent rapid prototyping system for stereolithography form the main focus of this paper.     

An adaptive process planning approach of rapid prototyping and manufacturing

This paper presents an adaptive approach to improve the process planning of Rapid Prototyping/Manufacturing (RP/M) for complex product models such as biomedical models. Non-Uniform Rational B-Spline (NURBS)-based curves were introduced to represent the boundary contours of the sliced layers in RP/M to maintain the geometrical accuracy of the original models. A mixed tool-path generation algorithm was then developed to generate contour tool-paths along the boundary and offset curves of each sliced layer to preserve geometrical accuracy, and zigzag tool-paths for the internal area of the layer to simplify computing processes and speed up fabrication. In addition, based on the developed build time and geometrical accuracy analysis models, adaptive algorithms were designed to generate an adaptive speed of the RP/M nozzle/print head for the contour tool-paths to address the geometrical characteristics of each layer, and to identify the best slope degree of the zigzag tool-paths towards achieving the minimum build time. Five case studies of complex biomedical models were used to verify and demonstrate the improved performance of the approach in terms of processing effectiveness and geometrical accuracy.     

A virtual prototyping system for rapid product development

This paper describes a virtual prototyping (VP) system that integrates virtual reality with rapid prototyping (RP) to create virtual or digital prototypes to facilitate product development. The proposed VP system incorporates two new simulation methodologies, namely the dexel-based and the layer-based fabrication approaches, to simulate the powder-based and the laminated sheet-based RP processes, respectively. The dexel-based approach deposits arrays of solid strips to form a layer, while the layer-based approach directly forms a complete layer by extruding the slice contours. The layer is subsequently stacked up to fabricate a virtual prototype. The simulation approaches resemble the physical fabrication processes of most RP systems, and are therefore capable of accurately representing the geometrical characteristics of prototypes. In addition to numerical quantification of the simulation results, the system also provides stereoscopic visualisation of the product design and its prototype for detailed analyses. Indeed, the original product design may be superimposed on its virtual prototype, so that areas with dimensional errors beyond design limits may be clearly highlighted to facilitate point-to-point analysis of the surface texture and the dimensional accuracy of the prototype. Hence, the key control parameters of an RP process, such as part orientation, layer thickness and hatch space, may be effectively tuned up for optimal fabrication of physical prototypes in subsequent product development. Furthermore, the virtual prototypes can be transmitted via the Internet to customers to facilitate global manufacturing. As a result, both the lead-time and the product development costs can be significantly reduced.     

面向领域的简化的快速需求分析方法

简化的面向领域的快速原型法，面向特定领域，根据数据库应用的特点，将需求分析分为两个阶段，采用建立某个特殊领域的需求分析的参考原型集的方法，简化了作为需求分析工具的系统原型的建设，这些面向特定领域的参考原型能够协助设计人员在需求分析阶段更好地完成需求采集工作，同时它们又是可进化的原型，经过反复修改使用，其表达能力将不断增强，将有效地节省同类系统开发的时间和费用，降低系统开发的风险。在这些简易、快速的原型基础上进行需求分析，大大地提高了需求分析的效率和准确性。     

面向快速制造扫描分区的凹多边形凸分解算法

提出了一个面向快速成型扫描路径规划的凹多边形凸分解算法。首先应用所提出的基于正负法搜索凹点对应的可见点的新算法来找出凹点的可见点串,然后结合所提出的适用于快速制造中扫描分区的剖分准则,利用权函数选择最佳剖分点,并合理使用辅助点,保证了剖分所得凸多边形的形态质量。该算法作为快速成形选区环形扫描路径规划软件的底层算法,在对待扫描的层面轮廓进行分区时得到了应用。     

PProto: An environment for prototyping parallel programs

This paper describes Parallel Proto (PProto), an integrated environment for constructing prototypes of parallel programs. Using functional and performance modeling of dataflow specifications, PProto assists in analysis of high-level software and hardware architectural tradeoffs. Facilities provided by PProto include a visual language and an editor for describing hierarchical dataflow graphs, a resource modeling tool for creating parallel architectures, mechanisms for mapping software components to hardware components, an interactive simulator for prototype interpretation, and a reuse capability. The simulator contains components for instrumenting, animating, debugging, and displaying results of functional and performance models. The Pproto environment is built on top of a substrate for managing user interfaces and database objects to provide consistent views of design objects across system tools.     

基于图像分析的快速成型预热优化方法*

针对激光快速成型预热工艺粉层温度检测与控制的难题,提出一种基于图像分析的快速成型预热优化方法。该方法使用VB编程及二次开发技术,利用Windows的应用程序编程接口函数,对粉层图像进行在线分析处理,析出图像的灰度直方图及预热效果指标。将当前粉层的预热效果指标与标准值进行比较,基于比较结果对预热工艺参数进行实时反馈控制。根据移动热源和固定热源给出了两种不同预热方式下的实现算法。该方法在软/硬件实现方面采用模块化设计,可嵌入已有的快速成型设备及控制程序中。实例分析结果表明,使用该方法进行预热优化控制,可提高成     

快速成型系统中自适应的直接切片算法的研究

为了解决CAD模型转换成STL模型时出现误差、均匀切片时加工时间和表面质量难以协调的问题,提出了自适应的直接切片算法.该算法调用商用软件中切片函数对模型直接切片,切片厚度选择采用自适应切片方法.首先求出能够表示模型垂直方向轮廓变化情况的参考曲线,然后在切片时根据参考曲线上各点处切线确定在该处的切片厚度.使用该算法避免了用三角面片逼近CAD模型时的误差,而且根据参考曲线上点的切线决定切片的厚度,不需要试切,在保证模型表面精度的同时提高了成型效率.     

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.     

A hardware-in-the-loop dynamics simulator for motorcycle rapid controller prototyping

The purpose of this research is to develop an innovative hardware-in-the-loop simulator for the purpose of motorcycle power train rapid controller prototyping. Proposed control algorithms can be validated using the developed setup. Such an in-lab validation saves time and development cost and thus is preferable during power train controller development process. The developed simulator includes an engine, a transmission, and a rear wheel from a real motorcycle. A powder brake is rigidly coupled to the rear wheel for road loading generation. A central computer is used to control the operation of the system and the measurement of system dynamics variables. An xPC system is also integrated in the system to provide the feasibility of power train control algorithm rapid prototyping. Comparison between field tests and simulation results show that the simulator can be used to evaluate the performance of different control algorithms for controller rapid prototyping in the laboratory. An example of power train control algorithm development featuring engine fuel injection control using the above rapid prototyping setup is also described.     

Reported effects of rapid prototyping on industrial software quality

Empirical data are required to determine the effect of rapid prototyping on software quality. We examine 34 published and unpublished case studies of the use of rapid prototyping in real-world software development. We identify common observations, unique events, and opinions. We develop guidelines to help software developers use rapid prototyping to maximize product quality and avoid common pitfalls.A protion of the results in this paper were reported in a previous paper entitled Rapid Prototyping and Software Quality: Lessons From Industry, that was presented at the 1991Pacific Northwest Software Quality Conference, Portland, Oregon, 1991.     

Hybrid rapid prototyping system using machining and deposition

Many rapid prototyping (RP) systems are commercially available, and others are introduced daily. RP has proven to be an effective tool for dramatically reducing the time and expense involved in the realization of a new products and for overcoming the bottlenecks of existing manufacturing processes. However, its fields of application are currently saturated, and the emphasis has moved towards using RP for short-run manufacture. The current need is for a technique that will produce finished parts of the required quality in the shortest possible time, and which meet this need, the focus now falls on improvements in production speed, accuracy, variety of materials, and cost. For these practical reasons, we concentrated on a new form of hybrid-RP system, which performs both deposition and machining in a single station. Our proposed system meets the requirements of material deposition (RP) and material removal (CNC) at the process planning and manufacturing level. We believe that this new production system, which incorporates a combined RP concept, offers an optimum manufacturing solution by adopting the advantages of the RP and CNC systems. In this paper, we describe the system architecture and the fabrication process in detail and present the framework of the process planning system and the concepts of the geometric algorithms involved in developing such an environment.     

A versatile virtual prototyping system for rapid product development

This paper presents a versatile virtual prototyping (VP) system for digital fabrication of multi-material prototypes to facilitate rapid product development. The VP system comprises a suite of software packages for multi-material layered manufacturing (MMLM) processes, including multi-toolpath planning, build-time estimation and accuracy analysis, integrated with semi-immersive desktop-based and full-immersive CAVE-based virtual reality (VR) technology. Such versatility makes the VP system adaptable to suit specific cost and functionality requirements of various applications.

The desktop-based VR system creates a semi-immersive environment for stereoscopic visualisation and quality analysis of a product design. It is relatively cost-effective and easy to operate, but its users may be distracted by environmental disturbances that could possibly diminish their efficiency of product design evaluation and improvement. To alleviate disturbance problems, the CAVE-based VR system provides an enclosed room-like environment that blocks out most disturbances, making it possible for a design team to fully concentrate and collaborate on their product design work.

The VP system enhances collaboration and communication of a design team working on product development. It provides simulation techniques to analyse and improve the design of a product and its fabrication processes. Through simulations, assessment and modification of a product design can be iterated without much worry about the manufacturing and material costs of prototypes. Hence, key factors such as product shape, manufacturability, and durability that affect the profitability of manufactured products are optimised quickly. Moreover, the resulting product design can be sent via the Internet to customers for comments or marketing purposes. The VP system therefore facilitates advanced product design and helps reduce development time and cost considerably.