Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2001-10-01
2004-08-24
Gandhi, Jayprakash N. (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S105000, C700S183000, C345S960000
Reexamination Certificate
active
06782305
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to sharing files amongst many users and more specifically to sharing geometric information and maintaining parametric consistency among elements in different software applications in a collaborative environment.
BACKGROUND OF THE INVENTION
As is known in the art, there is a trend in the development of products having multiple components or subsystems to outsource the complete design of a component or an entire subsystem. In such a product development effort, therefore, different companies are designing different components or subsystems which must eventually be mechanically mated as assemblies to provide the final product.
As is also known, a product development effort typically requires multiple re-designs of each component prior to selecting a final product design. In the case where two or more components must be mated together, a mechanical or geometric change to one of the components may affect the ability of that component to mate with the other components. It may be necessary to change the other components so that all of the components are mechanically compatible. Thus, in this instance, a change to the geometry of one component can cause other components to change. This raises the problem of sharing design information between the different companies designing each of the components.
As is also known, design companies (referred to herein as suppliers since they are supplying a design) typically utilize Computer Aided Design (CAD), Computer Aided Manufacturing (CAM), Computer Aided Engineering (CAE), etc. software applications. When designing components and/or subsystems. Different companies often have different types of CAD, CAM, CAE and such applications are typically not compatible i.e. it is not possible to directly share parametrically editable data between the different software applications at the different companies and other software applications. Thus, when multiple companies are designing different components or subsystems, it can become relatively difficult, time consuming and burdensome to share information and maintain consistency during a re-design process.
Within large organizations such as automobile manufacturers, for example, a common approach for resolving interoperability issues has been to standardize the design process on a single CAD package. This makes it easier to share native CAD models with dedicated CAM and CAE packages. Assembly modeling is homogenous, since all the parts are coming in the same CAD format, and thus parametric control on the parts can be maintained within the assembly model. However, this strategy also has negative consequences. From a supplier viewpoint, it may require the adoption of new tools that may not best suit their design needs, and they are required to reveal native models to other suppliers or the Original Equipment Manufacturer (OEM), such native models may contain design history that may be proprietary to the supplier. From the OEM viewpoint, flexible competition amongst potential suppliers is restricted to those using the standardized tool set.
An alternative strategy relies upon the exchange of component and subsystem geometry between organizations through the use of neutral files. Initial Graphics Exchange Specification (IGES) is a neutral file format originated by the National Institute of Standards and Technology (NIST) and adopted by the American National Standards Institute (ANSI) to facilitate transfer of geometric data. In practice, IGES has become the standard in CAD/CAM data exchange in the U.S.
The International Organization for Standardization (ISO) has developed its own neutral file format commonly known as STEP (Standard for the Exchange of Product Model Data, standard number ISO-10303-21). The standard itself is more than a geometric description format, attempting to incorporate a complete definition of the physical and functional characteristics of a product across its entire life cycle, including design, manufacture and support. Application Protocols (APs) define subsets of the STEP standard. The AP most relevant to geometry (AP
203
) is recognized by most major CAD and CAM systems, and is compatible with the Product Data Management (PDM) standards. Although parametric relations are not defined within AP
203
, data translation tends to be more robust and require less rework than IGES files. STEP is now used internationally, particularly in the aerospace and defense sectors.
STEP and IGES are the most robust and accepted standards for transferring geometry between CAD systems. AutoCAD's DXF (Data exchange Format) files have limited application and are not recognized as an official standard. VRML (Virtual Reality Modeling Language) is useful for visualization, but is not commonly used for importing geometry back into CAD systems. Similarly, STL (Standard Triangulated Language) files are appropriate for providing data to rapid prototyping devices, but do convert well between CAD systems. Although neutral files are not perfect, their relatively high level of functionality, ease of use, and acceptance by industry make them desirable as a means of transferring geometry between software applications, and in particular between CAD systems.
However, in a collaborative environment, the use of neutral files raises some issues related to content mapping, and to consistency maintenance of collections of elements. Content mapping is about associating the right low-level parametric geometric information within the neutral file, to the hi-level information as needed to maintain parametric consistency within the application or applications which uses the neutral file as a source of geometry. E.g. map the machined surface as represented within a CAM application to a specific surface stored in the neutral file. E.g. in assembly modeling, map the surfaces as defined in an assembly relation (e,g, a mating) to the right entities in the neutral file, or that the diameter of a bolt should match the diameter of a hole. Unless some automatic semantic interpretation capabilities are implemented within the application, content mapping is usually performed manually.
Consistency maintenance is about making sure that all the participants see an updated copy of the neutral file any time a change in the original native geometry has occurred. Geometry modifications can be classified as parametric changes to the model dimensions, or as changes to the model topology. Neither one is currently supported by any neutral file format. Changes to the topology (e.g. add/remove features) constitute a very hard problem for information sharing, and neutral file-based approaches are no exception to this.
Parametric changes are readily handled as long as they do not imply content re-mapping. Unfortunately, neutral file formats do not currently support parametric geometry, thus a new neutral representation is generated each time a parametric change occurs in the source geometry.
Manual generation and dissemination of updated neutral files is a viable option only for collaborative activities where geometric modifications are rare and easy-to-track events. Unfortunately this is not the case for most collaborative activities, thus the process needs to be automated to achieve a robust consistency control. Furthermore, the classical software architecture involving geometric information exchanges via neutral files allows only for parametric modifications driven by the original application that generated the geometric model. This unidirectional control flow is too limited for most collaborative environments: the capability of driving parametric geometry might be regarded as a valuable feature for the client applications that access the geometry through neutral files.
These considerations can be reformulated from the H-CAD (heterogenous CAD) viewpoint. Consider a heterogeneous assembly model built up from parts coming via neutral files created by different CAD applications. The proper mappings have been established to associate the assembly relations to the entities imported via neut
Liteplo William
Wallace David
Daly, Crowley & Mofford LLP
Gandhi Jayprakash N.
Massachusetts Institute of Technology
LandOfFree
Method of geometric information sharing and parametric... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of geometric information sharing and parametric..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of geometric information sharing and parametric... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3305541