MIVAS: A Multi-Modal Immersive Virtual Assembly System

Evaluation and planning of assembly processes in virtual environments have become an active research area in engineering community. However, planning of complex assemblies in virtual environments, especially large-scale virtual environments, is still hindered by limitations like unnatural user interaction, insufficient frame rates, and deficiencies in processing of assembly constraints. In this paper, we present MIVAS, a Multi-modal Immersive Virtual Assembly System. By viewing the virtual assembly system as a finite state machine, we incorporate tracked devices, force feedback dataglove, voice commands, human sounds, fully immersive 4-sided CAVE, together with optimization techniques for both complex assembly models and assembly operations to provide for engineers an intuitive and natural way of assembly evaluation and planning. Testing scenarios on disassembling different components of an intelligent hydraulic excavator are described. Special attention is paid upon such technical issues as interface between CAD packages and the CAVE virtual environment, natural and intuitive user interaction including realistic virtual hand interaction and force feedback, intelligent navigation for assembly operations, and real-time display of complex assemblies.

Automation of Process Planning for Rough Boring of Turned Components With Arbitrary Internal Geometry From a Semi-Finished Stock

This paper describes a novel method for automated process planning for rough boring of turned components with arbitrary internal geometry from a semi-finished stock. Earlier work has been reported on process planning for boring of components with monotonic internal geometry made from bar stock. This paper addresses the more general problem of process planning of parts with non-monotonic internal feature list from arbitrary given initial geometry, i.e., from a casting or from a semi-finished stock. With the algorithms developed, we are able to achieve full automation of all aspects of the process plan, including operations sequencing, parameter selection, NC code generation, etc. Thus, it becomes possible to go from design to NC code in a fully automated fashion. In the present work we focus on a tightly defined part family, which results in very simple but robust automation algorithms. This is in contrast to much of the reported work on automated process planning, which generally targets broad part families, leading to complex algorithms that fall short of complete design-to-NC automation.

Using Spreadsheet Modules to Augment Tolerance Dimensioning

This paper presents an easy-to-use spreadsheet module in Microsoft Excel to handle the implementation of the ANSI standards for tolerance fits for shafts and collars. The module makes use of drop-down menus and an embedded Visual Basic numerical algorithm to locate the correct tolerance ranges for a shaft and collar combination for the entire range of tolerances handled by the tables published in the ANSI standard. This module allows the quick implementation of designs and features a process that is less subject to errors associated with the traditional method of reading of the tolerance tables and transferring this information manually. The method is particularly helpful to students and inexperienced designers who first encounter the need to utilize tolerances in engineering designs. The paper presents an example application to illustrate the overall utility of the module.

Metamodel Defined Multidimensional Embedded Sequential Sampling Criteria

Collecting data to characterize an unknown space presents a series of challenges. Where in the space should data be collected? What regions are more valuable than others to sample? When have sufficient samples been acquired to characterize the space with some level of confidence? Sequential sampling techniques offer an approach to answering these questions by intelligently sampling an unknown space. Sampling decisions are made with criteria intended to preferentially search the space for desirable features. However, N-dimensional applications need efficient and effective criteria. This paper discusses the evolution of several such criteria based on an understanding of the behaviors of existing criteria, and desired criteria properties. The resulting criteria are evaluated with a variety of planar functions, and preliminary results for higher dimensional applications are also presented. In addition, a set of convergence criteria, intended to evaluate the effectiveness of further sampling are implemented. Using these sampling criteria, an effective metamodel representation of the unknown space can be generated at reasonable sampling costs. Furthermore, the use of convergence criteria allows conclusions to be drawn about the level of confidence in the metamodel, and forms the basis for evaluating the adequacy of the original sampling budget.

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.