A Method To Improve Matching Process by Shape Characteristics in Parametric Systems

10 pagesInternational audienceIn current parametric systems, the persistent naming issue (based on edge mappings of intersecting surfaces) is not as fully supported as it should be. Unpredictability and ambiguity of models often happen during design reevaluation within systems. This reference deficiency is widely treated in the literature, especially about non-planar entities during design construction. Although related works ensure the uniqueness of the references to topological entities, they often neglect the shape characteristics of surfaces and give results different from those expected during design reevaluation. We propose in this paper a method to add some additional information about surfaces to improve such works. We compute those information by decomposing surfaces according to hump(s) and/or hollow(s). More precisely, our method use local extremums and inflexion curves to obtain one hump or hollow per sub-surface. The existing matching processes replace every surface with their corresponding subsurfaces, leading to the right edge mappings

Document-Driven Design for Distributed CAD Services in Service-Oriented Architecture

Current computer-aided design (CAD) systems only support interactive geometry generation, which is not ideal for distributed engineering services in enterprise-to-enterprise collaboration with a generic thin-client service-oriented architecture. This paper proposes a new feature-based modeling mechanism—document-driven design—to enable batch mode geometry construction for distributed CAD systems. A semantic feature model is developed to represent informative and communicative design intent. Feature semantics is explicitly captured as a trinary relation, which provides good extensibility and prevents semantics loss. Data interoperability between domains is enhanced by schema mapping and multiresolution semantics. This mechanism aims to enable asynchronous communication in distributed CAD environments with ease of design alternative evaluation and reuse, reduced human errors, and improved system throughput and utilization

Constraint-Enabled Design Information Representation for Mechanical Products Over the Internet

Global economy has made manufacturing industry become more distributed than ever before. Product design requires more involvement from various technical disciplines at different locations. In such a geographically and temporally distributed environment, efficient and effective collaboration on design is vital to maintain product quality and organizational competency. Interoperability of design information is one of major barriers for collaborative design. Current standard CAD data formats do not support design collaboration effectively in terms of design information and knowledge capturing, exchange, and integration within the design cycle. Multidisciplinary design constraints cannot be represented and transferred among different groups, and design information cannot be integrated efficiently within a distributed environment. Uncertainty of specification cannot be modeled at early design stages, while constraints for optimization are not embedded in design data. In this work, a design information model, Universal Linkage model, is developed to represent design related information for mechanical products in a distributed form. It incorporates geometric and non-geometric constraints with traditional geometry and topology elements, thus allows more design knowledge sharing in collaborative design. Segments of design data are linked and integrated into a complete product model, thus support lean design information capturing, storage, and query. The model is represented by Directed Hyper Graph and Product Markup Language to preserve extensibility and openness. Incorporating robustness consideration, an Interval Geometric Modeling scheme is presented, in which numerical parameters are represented by interval values. This scheme is able to capture uncertainty and inexactness of design and reduces the chances of conflict in constraint imposition. It provides a unified constraint representation for the process of conceptual design, detailed design, and design optimization. Corresponding interval constraint solving methods are studied

Parametric CAD modeling: An analysis of strategies for design reusability

CAD model quality in parametric design scenarios largely determines the level of flexibility and adaptability of a 3D model (how easy it is to alter the geometry) as well as its reusability (the ability to use existing geometry in other contexts and applications). In the context of mechanical CAD systems, the nature of the feature-based parametric modeling paradigm, which is based on parent-child interdependencies between features, allows a wide selection of approaches for creating a specific model. Despite the virtually unlimited range of possible strategies for modeling a part, only a small number of them can guarantee an appropriate internal structure which results in a truly reusable CAD model. In this paper, we present an analysis of formal CAD modeling strategies and best practices for history-based parametric design: Delphi's horizontal modeling, explicit reference modeling, and resilient modeling. Aspects considered in our study include the rationale to avoid the creation of unnecessary feature interdependencies, the sequence and selection criteria for those features, and the effects of parent/child relations on model alteration. We provide a comparative evaluation of these strategies in the form of a series of experiments using three industrial CAD models with different levels of complexity. We analyze the internal structure of the models and compare their robustness and flexibility when the geometry is modified. The results reveal significant advantages of formal modeling methodologies, particularly resilient techniques, over non-structured approaches as well as the unexpected problems of the horizontal strategy in numerous modeling situations. (C)2016 Elsevier Ltd. All rights reserved.Camba, JD.; Contero, M.; Company, P. (2016). Parametric CAD modeling: An analysis of strategies for design reusability. Computer-Aided Design. 74:18-31. doi:10.1016/j.cad.2016.01.003S18317

A Generic Parametric Modeling Engine Targeted Towards Multidisciplinary Design: Goals and Concepts

This paper presents the design concept of a generic parametric modeling engine that is completely decoupled from geometry generation. Driven by requirements extracted from preliminary multidisciplinary airplane design, the presented software architecture provides a platform that enables an interplay of different modeling and simulation tools on the one hand, and their efficient execution in a parametric tree on the other hand. An integrated plugin system allows users to define custom plugins exposing arbitrary types and functions. All geometric functionality is provided via plugins, decoupling it entirely from the parametric engine. First, we specify the goals that the software framework needs to fulfill, elaborating on the requirements encountered in early aircraft design. Then, we describe the software architecture and its modules, realized as a C++ library. As such, the software is a back-end that can be used by third party developers to create user-friendly and interoperable tools. The core of the framework is a parametric engine called grunk with its integrated plugin system and serialization functionality. The key feature of grunk is the possibility for users to define custom types in plugins and their use in the parametric tree. Geometric modeling functionalities are provided through the plugins grocc and geo: the first integrating OpenCascade Technology's functionalities and the latter extending it. A major feature on the geometry side is the provision of derivatives through algorithmic differentiation, making the framework particularly suitable for gradient-based optimization applications. Finally, we demonstrate the use of the software via examples and show the results

A simplified software architecture for self-updating Building Information Models (BIM)

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 61-63).Building Information Modeling (BIM) is an emerging software technology that is revolutionizing the architecture, engineering, and construction (A/E/C) industry. BIM technology employs "object-based 3D models-containing the physical and functional characteristics of a facility-that serve as a repository for lifecycle information in an open, interoperable format" [1]. The major difference between BIM and Computer-Aided Design/Drafting (CADD) is that the former includes geometry and a plethora of building information while the latter includes only geometry. BIM utilization in the AEC industry has increased due to 1) BIM tools increasing productivity in design tasks; 2) the increasing number of private and government agencies that have instituted BIM requirements; 3) the pervasive use of computer analysis and simulations models; 4) the benefits of BIM as lifecycle management tool. Current literature shows trends of a transition from a "passive"-static model-based-approach to an "active"-dynamic model-based-approach. The active approach requires the integration of BIM with sensors to create "self-updating" building models. Previous research introduces the concept of a self-updating building model ([2], [31, [41). These systems involve complex software architecture and may perpetuate the problem of software interoperability. This thesis explores the following question: May a similar system be created to synthesize dynamic sensor data while improving upon previous research and simplifying the software architecture? The author describes a prototype system, called LiveBuild, which integrates commercial BIM software with other off-the-shelf software components to create a self-updating building model. LiveBuild is the first self-updating building model that operates as an extension to existing commercial BIM software. Therefore, the transition from static to active building models is as simple as installing a plug-in. LiveBuild may serve as the basis for future research in self-updating building by providing simplified system that is well integrated with state-of-the art commercial design software. Likewise, the prototype is applicable for professional practice by allowing firms to use their existing BIM software to perform "pilot projects" with self-updating technology. The current prototype supports an interface with single commercial BIM software (Autodesk Revit 2009) product however future prototypes may extend both the functions and interfaces for other BIM software.by Pierre Fuller.S.M

Probabilistic uncertainty in an interoperable framework

This thesis provides an interoperable language for quantifying uncertainty using probability theory. A general introduction to interoperability and uncertainty is given, with particular emphasis on the geospatial domain. Existing interoperable standards used within the geospatial sciences are reviewed, including Geography Markup Language (GML), Observations and Measurements (O&M) and the Web Processing Service (WPS) specifications. The importance of uncertainty in geospatial data is identified and probability theory is examined as a mechanism for quantifying these uncertainties. The Uncertainty Markup Language (UncertML) is presented as a solution to the lack of an interoperable standard for quantifying uncertainty. UncertML is capable of describing uncertainty using statistics, probability distributions or a series of realisations. The capabilities of UncertML are demonstrated through a series of XML examples. This thesis then provides a series of example use cases where UncertML is integrated with existing standards in a variety of applications. The Sensor Observation Service - a service for querying and retrieving sensor-observed data - is extended to provide a standardised method for quantifying the inherent uncertainties in sensor observations. The INTAMAP project demonstrates how UncertML can be used to aid uncertainty propagation using a WPS by allowing UncertML as input and output data. The flexibility of UncertML is demonstrated with an extension to the GML geometry schemas to allow positional uncertainty to be quantified. Further applications and developments of UncertML are discussed