Heather J Rea

Automated design knowledge capture and representation in single-user CAD environments

Current computer-aided design systems excel at recording the final design solution for an engineering problem; however, they are not as adept at capturing the individual designers rationale, knowledge or the process used during the design session. Being able to access this information will give insight into the reasons why key design decisions were made which, in turn, will support engineers who have to make revisions to the product in the future. Therefore, it would be beneficial if CAD systems were able to record design knowledge automatically. The research in this paper attempts to address this issue with a system that unobtrusively captures design processes and design knowledge by logging individual designer behaviour and system interactions while a CAD system is being used; user trials generated around 700 log files that were then analysed to extract these. In addition, various CAD system-independent representations were output to give a visual and formal representation of the processes that occurred. Overall, although carried out within a constrained design environment, this early knowledge capture work demonstrates the potential for automated knowledge capture and subsequent representations within CAD environments as well as the feasibility of design information push.

The Analysis of Design and Manufacturing Tasks Using Haptic and Immersive VR - Some Case Studies'

The use of virtual reality in interactive design and manufacture has been researched extensively but the practical application of this technology in industry is still very much in its infancy. This is surprising as one would have expected that, after some 30 years of research commercial applications of interactive design or manufacturing planning and analysis would be widespread throughout the product design domain. One of the major but less well known advantages of VR technology is that logging the user gives a great deal of rich data which can be used to automatically generate designs or manufacturing instructions, analyse design and manufacturing tasks, map engineering processes and, tentatively, acquire expert knowledge. The authors feel that the benefits of VR in these areas have not been fully disseminated to the wider industrial community and - with the advent of cheaper PC-based VR solutions - perhaps a wider appreciation of the capabilities of this type of technology may encourage companies to adopt VR solutions for some of their product design processes. With this in mind, this paper will describe in detail applications of haptics in assembly demonstrating how user task logging can lead to the analysis of design and manufacturing tasks at a level of detail not previously possible as well as giving usable engineering outputs. The haptic 3D VR study involves the use of a Phantom and 3D system to analyse and compare this technology against real-world user performance. This work demonstrates that the detailed logging of tasks in a virtual environment gives considerable potential for understanding how virtual tasks can be mapped onto their real world equivalent as well as showing how haptic process plans can be generated in a similar manner to the conduit design and assembly planning HMD VR tool reported in PART A. The paper concludes with a view as to how the authors feel that the use of VR systems in product design and manufacturing should evolve in order to enable the industrial adoption of this technology in the future.

A surface partitioning spectrum (SPS) for retrieval and indexing of 3D CAD models

Manual indexing of large databases of geometric information is costly and often impracticable. Because of this research into retrieval and indexing schemes has focused on the development of various 3D to 2D mappings that characterise a shape as a histogram with a small number of parameters. Many methods of generating such 2D signatures (i.e. histograms) have been proposed, generally based on geometric measures of say curvature or distance. However these geometric signatures lack information about topology and tend to become indistinct as the complexity of the shape increases. This work describes a new method for characterising both the geometry and topology of shapes in a single 2D graph, the surface partitioning spectrum (SPS). We evaluate the effectiveness of using the SPS with a neural network to assess the similarity of shapes within a test set.

Interpreting Three-Dimensional Shape Distributions

Abstract Effective content-based shape retrieval systems would allow engineers to search databases of three-dimensional computer-aided design (CAD) models for objects with specific geometries or features. Much of the academic work in this area has focused on the development of indexing schemes based on different types of three-dimensional to two-dimensional ‘shape functions’. Ideally, the shape function used to generate a distribution should be easy to compute and permit the discrimination of both large and small features. The work reported in this paper describes the properties of three new shape distributions based on computationally simple shape functions. The first shape function calculates the arithmetic difference between distributions derived (using the original D2 distance shape function) from both a three-dimensional model and its convex hull. The second shape function is obtained by sampling the angle between random pairs of facets on the object. The third shape function uses the surface orientation to filter the results of a distance distribution. The results reported in this paper suggest that these novel shape functions improve significantly the ability of shape distributions to discriminate between complex engineering parts.

The use of non-intrusive user logging to capture engineering rationale, knowledge and intent during the product life cycle

Within the context of life cycle engineering it is important that structured engineering information and knowledge are captured at all phases of the product life cycle for future reference. This is especially the case for long life cycle projects which see a large number of engineering decisions made at the early to mid-stages of a productpsilas life cycle that are needed to inform engineering decisions later on in the process. A key aspect of technology management will be the capturing of knowledge throughout the product life cycle. Numerous attempts have been made to apply knowledge capture techniques to formalise engineering decision rationale and processes; however, these tend to be associated with substantial overheads on the engineer and the company through cognitive process interruptions and additional costs/time. Indeed, when life cycle deadlines come closer these capturing techniques are abandoned due the need to produce a final solution. This paper describes work carried out for non-intrusively capturing and formalising product life cycle knowledge by demonstrating the automated capture of engineering processes/rationale using user logging via an immersive virtual reality system for cable harness design and assembly planning. Associated post-experimental analyses are described which demonstrate the formalisation of structured design processes and decision representations in the form of IDEF diagrams and structured engineering change information. Potential future research directions involving more thorough logging of users are also outlined.

Shapesifter: A retrieval system for databases of 3D engineering data

Large amounts of 3D data are being generated daily from increasingly diverse sources. In applications ranging from medical imaging and archival scanning of archaeological artifacts through to engineering and design, valuable geometric information is being recorded and stored. The size of these 3D databases make manual indexing time consuming, ineffective and often simply impracticable. Because of this, researchers have started to develop tools for automatically searching and organising these digital libraries of shape information. The most widespread and valuable form of 3D data are the design models created by commercial manufacturing companies. Engineering companies commonly have tens of thousands of 3D Computer‐Aided Design models stored on their computer systems. These models are used to communicate the exact shape and dimensions of components to both customers and subcontracting manufacturers. Consequently these models are of great value and importance to the companies. Currently 3D models (like engineering drawings) are indexed by alpha‐numeric ‘part numbers’ with a format unique to each company. Although this system of indexing works well in the context of ongoing maintenance and development of individual parts, it offers little scope for ‘data mining’ (i.e. exploration) of a companys inventory of designs. This paper describes an online system which allows collections of 3D models to be searched for components geometrically similar to a user‐defined target model. It is anticipated that such a system will encourage much