Combining constructive and equational geometric constraint solving techniques

In the past few years, there has been a strong trend towards developing parametric, computer aided design systems based on geometric constraint solving. An efective way to capture the design intent in these systems is to define relationships between geometric and technological variables. In general, geometric constraint solving including functional relationships requires a general approach and appropiate techniques toachieve the expected functional capabilities. This work reports on a hybrid method which combines two geometric constraint solving techniques: Constructive and equational. The hybrid solver has the capability of managing functional relationships between dimension variables and variables representing conditions external to the geometric problem. The hybrid solver is described as a rewriting system and is shown to be correct.Postprint (published version

Productivity Improvement by Using Social-Annotations about Design Intent in CAD Modelling Process

[EN] This paper focuses on the New Product Development Process (NPDP) area to contribute to increasing the productivity of CAD users by means of an improved design intent communication using a social-annotation technique. Design teams operate in a similar way to an online social network, and CAD models are not just only a 3D geometry representation, as they reflect the result of an specific modeling strategy, that usually constrains the future capability for modification and reuse of the existing 3D model. Considering this context, this work tries to assess the impact of annotations in the engineering change process in order to determine its influence in the user performance during this process. Preliminary experimental results obtained from several experiments with Spanish CAD students indicate that it is possible to reduce the time needed to perform engineering changes in existing models into a 10-20% range, if those CAD models provide annotations explaining the original design intent. © 2011 Springer-Verlag.Alducin, G.; Contero, M.; Martín Guitérrez J.; Guerra-Zubiaga, D.; Johnson, M. (2011). Productivity Improvement by Using Social-Annotations about Design Intent in CAD Modelling Process. Lecture Notes in Computer Science. 6778:153-161. doi:10.1007/978-3-642-21796-8_16S1531616778Anderl, R., Mendgen, R.: Parametric design and its impact on solid modeling applications. In: Third ACM Symposium on Solid Modelling and Applications, pp. 1–12. ACM, New York (1995)Vila, C., Contero, M., Company, P.: Extended modeling, a tool for cooperative design. In: 6th International Conference on Concurrent Enterprising, Tolouse France (2000)Anderl, R., Mendgen, R.: Analyzing and optimizing constraint-structures in complex parametric CAD models. In: Bruderlin, B., Roller, D. (eds.) Geometric Constraint Solving and Applications, pp. 58–81. Springer, Berlin (1998)Hartman, N.W.: The development of expertise in the use of constraint-based CAD tools. Eng. Design Graph. J. 68, 14–26 (2004)Rynne, A.: AC 2007-2132: Cognitive modelling strategies for optimum design intent in parametric modelling (PM). American Society for Engineering Education (2007)Guerra-Zubiaga, D.A.: A Model to enable Knowledge Maintenance: Supporting Manufacturing Decisions. VDM Verlag, Germany (2009); ISBN 978-3639209983Hartman, N.W.: Defining expertise in the use of constraint-based CAD tools by examining practicing professionals. Eng. Design Graph. J. 68, 6–15 (2005)Bhavnani, S.K., Garrett, J.H.J., Shaw, D.S.: Leading indicators of CAD experience: Paper presented at the Proceedings of Computer-Aided Architectural Design Futures CAAD Futures 1993, pp. 313–334 (1993)Johnson, M.D., Diwakaran, R.P.: Assessing the effect of incentive on computer-aided design intent. In: The ASME 2009 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference, San Diego, California, pp. 523–532 (2009)Polkinghorne, D.E.: Phenomenological research methods. In: Valle, R.S., Halling, S. (eds.) Existential-Phenomenological Perspectives in Psychology, pp. 41–60. Plenum, New York (1989)Meyer, M.A., Booker, J.M.: Eliciting and analyzing expert judgment: A practical guide. Academic Press, San Diego (1991)Reddy, J.M., Finger, S., Konda, S., Subrahmanian, E.: Design as Building and Reusing Artifact Theories: Understanding and Supporting Growth of Design Knowledge. In: The Design Productivity Debate. Springer, Heidelberg (1998)Bucciarelli, L.L.: Designing engineers. MIT Press, Cambridge (1994)May, P., Ehrlich, H.C., Steinke, T.: Mapping Sociotechnical Networks in the Making. In: Bowker, G., Star, S.L., Turner, W., Gasser, L. (eds.) Beyond the Great Divide,Technical Systems and Co-operative Work, Lawrence Erlbaum, Mahwah (1997)Bhavnani, S.K., Garrett, J.H.: Leading Indicators of CAD Experience. In: Flemming, U., Van Wyk, S. (eds.) CAAD Futures 1993, pp. 313–334. Elsevier Science Publishers, Netherlands (1993

A case study on non-parametric design method in ODM collaborative product development

Abstract: There are two distinct solid design methodologies -parametric and non-parametric approaches. In the past 20 years, most industrial CAD users have been upgrading their CAD design methods from the non-parametric approach to the parametric one. However, with the new trends of globalisation, outsourcing and collaboration, it is timely to ask whether the parametric design is still effective. In this paper, a case study based on the non-parametric CAD modelling approach with a distributed collaborative design system is presented. A real project for a typical mechatronic product is studied in depth. Based on the case study and field observations, we have found that non-parametric modelling methodology enables collaboration in several ways. Further, the non-parametric modelling methodology shows many advantages. A comparative analysis has also been carried out via matching ODM design activities to the strengths and weaknesses of the two approaches. Finally, suggestions for future research directions of collaborative design are given. Keywords: collaborative product development; parametric design; non-parametric design; feature-based design; design methodology. Reference to this paper should be made as follows: Ma, Y-S. (2005) 'A case study on non-parametric design method in ODM collaborative product development', Int

Analyzing the Effects of Incentives and Model Attributes on CAD Model Creation and Alteration

Modern computer-aided design (CAD) systems have contributed significantly towards product development cycle time reduction and product quality improvement. To enhance the performance of CAD systems engineers must be able to create CAD models of conceptual designs quickly; at the same time CAD models must be easy to alter, so as to accommodate the rapid changes that the design undergoes through the lifecycle. However, there is no agreement in the way CAD models should be created to accomplish these goals. This work attempts to assess the effects of incentives on CAD model attributes during model creation and alteration; the effects of CAD model attributes on alteration are also investigated. Its aim is to derive prescriptions based on empirical evidence to improve CAD model creation and alteration efficiency. The CAD models under study are created by three sets of participants – students from a junior level CAD course, students from a senior level CAD course and experienced engineers involved in product development activities. The participants are incentivized to create and alter CAD models of designs they are provided with. The results indicate that upon removal of incentives, engineers (both students and professionals) tend to compromise on proper modeling procedures. Experts are quicker and adhere to commonly agreed correct modeling procedures during CAD model creation and alteration than students. The results also indicate that it is beneficial for alteration to construct a model with several simple features as opposed to a few complex features and that these features be fully constrained. Maintaining the traditional feature sequence improves the perception of the model. The retention and alteration of features (as opposed to deletion) is also shown to be positively correlated with model perception ratings