A Comparison of Two Collision Detection Libraries in a Haptic Simulation Environment

Modeling the interaction between dynamic objects in a haptically enabled virtual environment requires high-speed collision detection. We present an independent comparison of two publicly available collision detection libraries, V-Clip and SWIFT++, as they perform in our assembly and disassembly simulation. Three assembly sequences, differing only by the complexity of the objects involved, are tested and compared based on speed of execution. In the process, some potentially limiting factors experienced while using these libraries are exposed.

Internet Design Studio

In most instances engineering design courses are offered during the senior year of the undergraduate curriculum. These senior level design courses allow the students to apply different engineering concepts to design a product, with the expectation of preparing engineering students for a distributed and global workplace. Another possible alternative is to provide a simulated education environment where students can design products in a distributed and collaborative environment. The use of Internet in education has opened the possibility to explore and adopt new approaches to teach distributed collaborative engineering design and analysis. The Internet Design Studio, presented in this paper, tries to fulfill this need. In the Internet Design Studio each student is provided with a virtual design studio space for each project. The design studio spaces can be imagined as a virtual space containing design tools, applications, software and theoretical materials that facilitates students to design and perform analysis. Conceptually, a student enters the studio space and grabs appropriate tools to perform different design tasks. The design tools in the Internet Design Studio are web-based and support collaborations by allowing multiple users to view, discuss, create and utilize same models of the product to perform analysis. In this paper the framework of the Internet Design Studio is presented. The applicability of the framework is demonstrated through the use of several multi-designer collaborative design tools.

STEP, XML, and UML: Complementary Technologies

One important aspect of product lifecycle management (PLM) is the computer-sensible representation of product information. Over the past fifteen years or so, several languages and technologies have emerged that vary in their emphasis and applicability for such usage. ISO 10303, informally known as the Standard for the Exchange of Product Model Data (STEP), contains the high-quality product information models needed for electronic business solutions based on the Extensible Markup Language (XML). However, traditional STEP-based model information is represented using languages that are unfamiliar to most application developers. This paper discusses efforts underway to make STEP information models available in universal formats familiar to most business application developers: specifically XML and the Unified Modeling Language™ (UML®). We also present a vision and roadmap for future STEP integration with XML and UML to enable enhanced PLM interoperability.

Design and Deformation of CAD Surface Models With Haptics

With traditional two-dimensional based interfaces, many CAD surface models, such as automobile bodies and ship hulls, are difficult to design and edit due to their 3D nature. This paper discusses the haptic-based deformation for the design of CAD surface models. With haptic devices (force feedback interfaces) designers can, in virtual space, touch a native B-rep CAD model, and use their tactile senses to manipulate it by pushing, pulling and dragging its surfaces in a natural 3D environment. The paper presents shape control functions. By using the shape functions, designers can directly manipulate and deform a selected region of a surface to the desired shape, and generate complex geometry with simple operations. Force feedback gives designers the greatest flexibility for the design of complex surfaces.

First Steps Towards an All Embracing Relations-Based Modeling

The focus in computer-aided design is shifting from geometric aspects to functional aspects and from the detail design to a multi-aspect conceptual design. As a consequence, new concepts are emerging and being tested, for instance, for comprehensive geometric and functional modeling in conceptual design. This paper introduces a new approach, which has been called relations-based design. Relations are existential, manifestation and behavioral associations, dependencies and interactions between human, artifacts and environments. Nucleus is introduced as a generic modeling entity, which includes two regions of one or two objects that are interconnected by a system of relations in a particular situation. A design concept (or an artifact) is conceived as a purposeful composition of specific instances of nuclei. The nucleus can be instantiated at multiple levels such as entity, component, subassembly and assembly. A set of relations has been predefined to express qualitative and quantitative associations, dependencies and interactions between objects in a parameterized form on these levels. As a modeling entity, the nucleus offers many advantages in multi-aspect conceptual modeling by integrating incomplete and uncertain geometric, structural, physical and behavioral modeling. The paper introduces the foundational theories, the most important mathematical definitions, and the concept of information management. Finally, it points at some advantages of relations based modeling in the context of application cases comparing it with the physical modeling offered in a commercial system.

Modeling and Representation of Manufacturing Knowledge for DFM Systems

The manufacturing knowledge today spans a vast spectrum, from manufacturing process capability/constraint, precedence, algorithms/heuristics of performing feature recognition, process planning and manufacturing time/cost estimation, to Design for Manufacturing (DfM) tactics and strategies. In this paper, different types of manufacturing knowledge have been identified and the ways to represent and apply them are described. An information model is developed as the backbone to integrate other existing tools into the framework. A computational framework is presented to help the manufacturing knowledge engineers formulize their knowledge and store it into the computer, and help the designers systematically analyze the manufacturability of the design.

A Visualization-Based Approach to Engineering Kinematics Using Cognitive Models

Visualization and spatial reasoning are integral to developing an understanding of contemporary sciences. They form the basis for understanding a wide variety of topics across science, mathematics and engineering, including molecular structures, topologies, motion and forces, and manufacturing processes. Within engineering, it can be argued that challenging and time consuming topics such as kinematics can be better taught by faculty, and hence better understood and appreciated by students, by advancing our understanding of human visualization and spatial reasoning and using this knowledge to develop computer-based visualization instruction in ways that maximize their effectiveness. The achievement of such a goal will require importing proven extant theories from other fields such as psychology, education, engineering and computer science. This paper presents the results of one such effort for teaching engineering kinematics. The motivation for this work can be found in cognitive science literature, where motion comprehension has been identified and studied as a mental task. Accordingly, a major task in doing this work involved the study of cognitive models of motion comprehension, and identifying key stages present in them. Mapping such key stages in motion comprehension on to kinematics domain, this paper presents the framework for the visual comprehension based pedagogical approach to kinematics. A web-based gear-trains tutor has been developed to demonstrate this concept. Results from the tests on a controlled population of engineering students are presented and the efficacy of a visual comprehension based approach as an instructional tool is discussed.

Direct Manipulation of Feature Models in Web-Based Collaborative Design

Providing advanced 3D interactive facilities to users of a client-server collaborative modeling system presents a great challenge when thin clients are involved, mainly due to their lack of both a full-fledged CAD model and adequate modeling and solving functionalities. This paper presents a new approach that provides a convenient representation of feature model data suitable for direct manipulation of feature models at such clients. In particular, feature handles are proposed to support interactive feature editing. This approach combines all advantages of a thin client approach with the sort of 3D direct manipulation facilities usually only found in powerful standalone CAD systems.

N-Rep: A Neutral Feature Representation to Support Feature Mapping and Data Exchange Across Applications

The proliferation of different feature based systems has made feature data exchange an important issue. Unlike geometry data exchange, where different representations use the same fundamental concepts; the most popular being B-Rep and CSG [Shah et al. 88], different feature representation schemes use different concepts to represent features corresponding to the application and domain. Therefore, feature data transfer between applications not only involves transfer of instance data but also transformation of feature concepts. This paper presents N-Rep, an application independent declarative language, for feature definition that includes topology, topological relationships, geometry, geometric relationships, parameters and parametric relationships. N-Rep has been designed to serve three roles, viz., (a) to generate feature recognition algorithms for recognizing features from geometry, (b) to generate feature producing procedures to be used in design by feature approaches, and (c) to serve as a neutral feature data exchange medium between representations.

Knowledge Management and Support Environment in Early Phases of Design Process

Most of the time, starting new design projects based on innovative product concepts is a strategic but complicated process. Individual initiatives and the development of new ideas take place within conflicting contexts combining technical, economical and social aspects. During theses phases actors have to formalize new ideas, to exchange them and to collaborate to promote them. Traditional tools do not support such activities. We propose in this paper a new approach dedicated to the product development process from the early phases to the embodiment design phases. Metamodeling techniques and new tools (ID2 - Innovation Development and Diffusion - and CE - Constraint Explorer -) are proposed in order to support those phases ensuring the collaboration and the interaction between design actors, the knowledge and information management, the development of innovative ideas, and the improvement of embodiment design solutions. More over we propose to link our tools to a PLM environment to improve the sharing and the management of information, documents and design solutions in order to foster collaboration. The main objective of our implementation is to foster innovation during design process by improving sharing and reuse of innovative ideas and allowing the organization to identify rapidly best consensus for design solutions.