Contour curve reconstruction from cloud data for rapid prototyping

In this study, a method for generation of sectional contour curves directly from cloud point data is given. This method computes contour curves for rapid prototyping model generation via adaptive slicing, data points reducing and B-spline curve fitting. In this approach, first a cloud point data set is segmented along the component building direction to a number of layers. The points are projected to the mid-plane of the layer to form a 2-dimensional (2D) band of scattered points. These points are then utilized to construct a boundary curve. A number of points are picked up along the band and a B-spline curve is fitted. Then points are selected on the B-spline curve based on its discrete curvature. These are the points used as centers for generation of circles with a user-define radius to capture a piece of the scattered band. The geometric center of the points lying within these circles is treated as a control point for a B-spline curve fitting that represents a boundary contour curve. The advantage of this method is simplicity and insensitivity to common small inaccuracies. Two experimental results are included to demonstrate the effectiveness and applicability of the proposed method.     

Modelling cloud data using an adaptive slicing approach

In reverse engineering, the conventional surface modelling from point cloud data is time-consuming and requires expert modelling skills. One of the innovative modelling methods is to directly slice the point cloud along a direction and generate a layer-based model, which can be used directly for fabrication using rapid prototyping (RP) techniques. However, the main challenge is that the thickness of each layer must be carefully controlled so that each layer will yield the same shape error, which is within the given tolerance bound. In this paper, an adaptive slicing method for modelling point cloud data is presented. It seeks to generate a direct RP model with minimum number of layers based on a given shape error. The method employs an iterative approach to find the maximum allowable thickness for each layer. Issues including multiple loop segmentation in layers, profile curve generation, and data filtering, are discussed. The efficacy of the algorithm is demonstrated by case studies.     

Rapid prototyping technology: applications and benefits for rapid product development

In recent years, rapid prototyping technology (RPT) has been implemented in many spheres of industry, particularly in the area of product development. Existing processes provide the capability to rapidly produce a tangible solid part, directly from three dimensional CAD data from a range of materials such as photocurable resin, powders and paper. This paper gives an overview of the growth and trend of the technology, areas of applications and its significant benefits to manufacturing industries.     

On the development of a haptic system for rapid product development

This paper presents a system development that extends haptic modeling to a number of key aspects in product development. Since haptic modeling has been developed based on physical laws, it is anticipated that a natural link between the virtual world and practical applications can be established based on haptic interaction. In the proposed system, a haptic device is used as the central mechanism for reverse engineering, shape modeling, real time mechanical property analysis, machining tool path planning and coordinate measuring machine (CMM) tolerance inspection path planning. With all these features in a single haptic system, it is possible to construct a three dimensional part by either haptic shape modeling or reverse engineering, then performing real-time mechanical property analysis in which the stiffness of a part can be felt and intuitively evaluated by the user, or generating collision free cutter tool path and CMM tolerance inspection path. Due to the force feed back in all of the above activities, the product development process is more intuitive, efficient and user-friendly. A prototype system has been developed to demonstrate the proposed capabilities.     

STL rapid prototyping bio-CAD model for CT medical image segmentation

This paper presents a simple process to construct 3D rapid prototyping (RP) physical models for computer tomography (CT) medical images segmentation. The use of stereolithography (STL) triangular meshes as a basis for RP construction facilitates the simplification of the process of converting CT images to an RP model. This is achieved by constructing the STL triangular meshes directly from data points without having to draw the curve model first. The grey prediction algorithm is used to sort contour point data in each layer of the medical image. The contour difference detection operation is used to sequence the points for each layer. The 3D STL meshes are then constructed by this proposed layer-by-layer sequence meshes algorithm to build the STL file. Once this STL file is saved, a 3D physical model of the medical image can be fabricated by RP manufacturing, and its virtual reality model can also be presented for visualization. CT images of a human skull and femur bone were used as the case studies for the construction of the 3D solid model with medical images. The STL models generated using this new methodology were compared to commercial computer-aided design (CAD) models. The results of this comparative analysis show that this new methodology is statistically comparable to that of the CAD software. The results of this research are therefore clinically reliable in reconstructing 3D bio-CAD models for CT medical images.     

Development of a rapid prototyping design advice system

This paper describes the initial development of a computer based Rapid Prototyping Design Advice System. The system is intended to assist the designer or project manager, particularly those in small and medium sized companies, in planning the prototyping stage of product development. It provides the user with an efficient and user friendly development aid which uses information obtained from the user and Computer Aided Design data to recommend suitable rapid prototyping solutions.     

Model-driven rapid prototyping with programmed graph transformations

Modern software systems are constantly increasing in complexity and supporting the rapid prototyping of such systems has become crucial to check the feasibility of extensions and optimizations, thereby reducing risks and, consequently, the cost of development. As modern software systems are also expected to be reused, extended, and adapted over a much longer lifetime than ever before, ensuring the maintainability of such systems is equally gaining relevance.In this paper, we present the development, optimization and maintenance of MoSo-PoLiTe, a framework for Software Product Line (SPL) testing, as a novel case study for rapid prototyping via metamodelling and programmed graph transformations.The first part of the case study evaluates the use of programmed graph transformations for optimizing an existing, hand-written system (MoSo-PoLiTe) via rapid prototyping of various strategies. In the second part, we present a complete re-engineering of the hand-written system with programmed graph transformations and provide a critical comparison of both implementations.Our results and conclusions indicate that metamodelling and programmed graph transformation are not only suitable techniques for rapid prototyping, but also lead to more maintainable systems.     

Surface roughness visualisation for rapid prototyping models

When considering the use of rapid prototyping (RP), there are many questions a designer might ask. One such question is “what build orientation should be used to minimise the adverse effects of surface roughness?” At present, this decision is often made in an intuitive way or sometimes overlooked completely. This paper describes a methodology and software implementation that provides the designer with a computer graphics based visualisation of RP model surface roughness. This enables the build orientation to be determined as a result of increased designer knowledge. The surface roughness values were obtained through an extensive empirical investigation of several RP techniques. These are used as the database for a visualisation algorithm that represents varying surface roughness of the RP model as colour shading within a CAD image. The nature of the empirical measurements is analysed and the functionality of the software algorithm is described. Examples are given that demonstrate the use and benefits of the methodology. Finally, conclusions are drawn as to the significance of the work and future research directions are outlined.     

STL file generation from measured point data by segmentation and Delaunay triangulation

For the generation of the models in RP, a laser scanner is currently used a lot due to the fast measuring speed and high precision. Direct generation of STL file from the scanned data has a great advantage in that it can reduce the time and error in modeling process. The reduction of the number of point data is important while generating STL file directly from the measured point data with maintaining their precision.A new approach is addressed to reduce the amount of data by segmentation and Delaunay triangulation. Basic experiments are performed to apply the algorithm developed to real models. Different results are incurred by user-defined criteria, and some dominant output characteristics according to the user input are reviewed and analyzed. The program developed in the research generates an STL files efficiently with automated data reduction. Several criteria are specified in order to maintain the characteristics of the feature and satisfy the needs in real workshops.     

Adaptive tool-path generation of rapid prototyping for complex product models

Rapid prototyping (RP) provides an effective method for model verification and product development collaboration. A challenging research issue in RP is how to shorten the build time and improve the surface accuracy especially for complex product models. In this paper, systematic adaptive algorithms and strategies have been developed to address the challenge. A slicing algorithm has been first developed for directly slicing a Computer-Aided Design (CAD) model as a number of RP layers. Closed Non-Uniform Rational B-Spline (NURBS) curves have been introduced to represent the contours of the layers to maintain the surface accuracy of the CAD model. Based on it, a mixed and adaptive tool-path generation algorithm, which is aimed to optimize both the surface quality and fabrication efficiency in RP, has been then developed. The algorithm can generate contour tool-paths for the boundary of each RP sliced layer to reduce the surface errors of the model, and zigzag tool-paths for the internal area of the layer to speed up fabrication. In addition, based on developed build time analysis mathematical models, adaptive strategies have been devised to generate variable speeds for contour tool-paths to address the geometric characteristics in each layer to reduce build time, and to identify the best slope degree of zigzag tool-paths to further minimize the build time. In the end, case studies of complex product models have been used to validate and showcase the performance of the developed algorithms in terms of processing effectiveness and surface accuracy.     

Progress towards an international standard for data transfer in rapid prototyping and layered manufacturing

This paper discusses the informational requirements of rapid prototyping and layered manufacturing (RPLM). The study is motivated by the recent decision to embark on the development of a new Application Protocol for the international standard ISO 10303, specifically to handle layered manufacturing information.

The most common industrial use of RPLM today is for rapid prototyping, but a wider view of it as a flexible fabrication technology is taken here, to allow for future developments. Its use in building functional metallic parts under computer control has already been demonstrated, and commercial RPLM machines for building production parts are already being marketed.

The paper includes a survey of current and proposed data formats for communication between the various stages of the RPLM process. In comparing them, particular attention is given to the issue of extensibility to meet future needs. In this last respect, special emphasis is given to materials-related and other non-geometric information needed for fabricating multi-material objects and objects with graded material properties.     

NURBS-based adaptive slicing for efficient rapid prototyping

This paper presents slicing algorithms for efficient model prototyping. The algorithms directly operate upon a non-uniform rational B-spline surface model. An adaptive slicing algorithm is developed to obtain an accurate and smooth part surface. A selective hatching strategy is employed to further reduce the build time by solidifying the kernel regions of a part with the maximum allowable thick layers while solidifying the skin areas with adaptive thin layers to obtain the required surface accuracy. In addition, it provides a generalization to the containment problem with mixed tolerances for slicing a part. The article also developed a direct method for computing skin contours for all tolerance requirements. Some case studies are presented to illustrate the developed algorithms and the selective hatching and adaptive slicing strategy. The developed algorithms have been implemented and tested on a fused deposition modeling rapid prototyping machine. Both the implementation and test results are discussed in the paper.     

Wiki-based rapid prototyping for teaching-material design in e-Learning grids

Grid computing environments with abundant resources can support innovative e-Learning applications, and are promising platforms for e-Learning. To support individualized and adaptive learning, teachers are encouraged to develop various teaching materials according to different requirements. However, traditional methodologies for designing teaching materials are time-consuming. To speed up the development process of teaching materials, our idea is to use a rapid prototyping approach which is based on automatic draft generation and Wiki-based revision. This paper presents the approach named WARP (Wiki-based Authoring by Rapid Prototyping), which is composed of five phases: (1) requirement verification, (2) query expansion, (3) teaching-material retrieval, (4) draft generation and (5) Wiki-based revision. A prototype system was implemented in grid environments. The evaluation was conducted using a two-group t-test design. Experimental results indicate that teaching materials can be rapidly generated with the proposed approach.     

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.     

Tool-path generation from measured data

Presented in the paper is a procedure through which 3-axis NC tool-paths (for roughing and finishing) can be directly generated from measured data (a set of point sequence curves). The rough machining is performed by machining volumes of material in a slice-by-slice manner. To generate the roughing tool-path, it is essential to extract the machining regions (contour curves and their inclusion relationships) from each slice. For the machining region extraction, we employ the boundary extraction algorithm suggested by Park and Choi (Comput.-Aided Des. 33 (2001) 571). By making use of the boundary extraction algorithm, it is possible to extract the machining regions with O(n) time complexity, where n is the number of runs. The finishing tool-path can be obtained by defining a series of curves on the CL (cutter location) surface. However, calculating the CL-surface of the measured data involves time-consuming computations, such as swept volume modeling of an inverse tool and Boolean operations between polygonal volumes. To avoid these computational difficulties, we develop an algorithm to calculate the finishing tool-path based on well-known 2D geometric algorithms, such as 2D curve offsetting and polygonal chain intersection algorithms.     

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.     

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.     

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.     

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.     

A framework for rapid computational prototyping of manufacturing entities

A framework for enhancement of conceptual tools for rapid computational prototyping of manufacturing entities is presented. A typical manufacturing entity (i.e. manufacturing system and/or individual part) is hierarchically represented in a computer and coupled with applications by dividing its information content into three computational elements: data, drawing and user interface. The information content is divided in this way because each of the above elements has a sufficiently distinct requirement for an efficient computer implementation. Although independent advances have taken place in computer data representation by highly efficient and focused data structures, in drawing representation by sophisticated computer graphics, as well as in user interface by a variety of interface media, these advances cannot be directly utilized in the design of a manufacturing entity unless they are efficiently integrated by relatively small programming effort as is deseribed in this rapid prototyping framework. The framework is implemented in object-oriented programming. A breadth of application areas for the framework is illustrated, and specific details are illustrated with reference to depth in one application area.