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Automotive Industry

Digital mock-up grows up: digital mock-up tools sit nicely between heavy-weight, complex CAD systems and lightweight CAD viewers. Every automotive enterprise should have one of these tools. And in time, will have one

Automotive Design & Production, June, 2007 by Lawrence S. Gould

"If computer-aided design [CAD] wasn't so hard to use, took so much space, and sucked so much compute power, you wouldn't need DMU because you could use CAD. But, you can't, so that's why there's DMU," sums up Charles Foundyller, CEO of the research firm Daratech Inc. (Cambridge, MA; www.daratech.com), speaking of the relevance of digital mock-up (DMU). Simply put, DMU is the computerized version, the 3D visualization, of parts and assemblies. DMU tools let users visualize, animate, dimension, manipulate, explode, fly through, cut away, and check the clearance and interference of part and assembly designs. And so much more.

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With this functionality come changes. One of the more important changes, says John MacKrell, senior consultant at the Ann Arbor-based research firm CIMdata (www.cimdata.com), has been in moving "DMU out of the CAD environment, making it available to users who do not have a CAD system. This decoupling allows us to do a couple of really neat things." First, whole new classes of users--non-CAD users--now have access to DMU capabilities. Second, it speeds design analysis. "Sometimes it's good enough just to assign constraints and play with the model completely CAD-neutral environment without having real, honest-to-God analysis going on in the background." Third, decoupling lets users apply DMU capabilities to part and assembly files created by different people on different systems--in a single environment, namely DMU. It also opens DMU to a wide variety of enterprise systems.

Collaboration comes to CAD

This reach-out-and-touch-someone or-something capability of DMU is well-incorporated in Seemage, the DMU tool from Seemage, Inc. (Newton, MA; www.seemage.com). Seemage is based on extensible Markup Language (XML). Everything associated with a part or subassembly (including assembly trees, geometry, part names and layers, and product lifecycle management [PLM] attributes) are extracted automatically from native CAD files and converted to the XML Seemage format. (Contrast this with carrying the whole parametric, feature, history-based view of a 3D world.) Seemage displays are a hybrid representation that mixes tessellated and exact data. Because it's all based on XML, which is fundamentally simple text, Seemage can automatically compress native 3D CAD models up to 99%. Because of that, explains Jean-Jacques Grimaud, vice president of business development for Seemage, the DMU tool can "probably view up to 100,000 to 200,000 parts [at one time]. We work comfortably with 30,000 to 40,000 parts on a desktop."

These lightweight XML-based files, continues Alex Neihaus, Seemage's director of marketing, "are infinitely malleable in the hands of whomever is trying to produce some documentation." This is because XML is designed for interchange and is easily understood and programmed. Users can, for instance, combine the XML-based 3D data with other part data from other systems, such as enterprise resource planning (ERP), to create documentation beyond that required by engineering, such as marketing brochures, parts catalogs, maintenance procedures, and engineering change documents.

Seemage Sync fully associates the XML data in Seemage with enterprise systems. This way, changes in metadata, geometry, tree structure, bills of material (BOM), or manufacturing information will automatically be updated in the mockup and other Seemage outputs. (This associativity is bidirectional; changes resulting from using Seemage can be reflected back into, for example, core CAD files.) With Seemage Sync, users can create interactive parts catalogs and BOMs, for example, that can be exported in HTML, PDF, and other document formats.

This associativity puts a different slant on engineering management. Explains Neihaus, "XML permits a level of decentralization without chaos because you can give non-technical people 'point tools' to solve immediate and pressing problems. Then, because there's this XML infrastructure under it, you can later integrate those tools in almost any way." Case in point: Conventional PLM systems are engineering--and server-based; their focus is from engineering out to the rest of the enterprise. Seemage, on the other hand, can be deployed on a desktop first, then later integrated with PLM. "Our secret sauce is being able to do both--be deployed 'in either direction,' either as a desktop application or integrated to back-end systems--and end up with a high-fidelity, high-quality, easy-to-use collaborative tool."

DMU for electronics

DMU is not just for visualizing mechanical systems. The electronic design automation (EDA) version of AutoVue from Cimmetry Systems Corp. (Montreal, QC, Canada; www.cimmetry.com) combines mechanical parts with electronic components. Among other functions, AutoVue EDA can check violations on printed circuit boards (PCBs), such as pad/trace/component clearances, drill hole sizes, via counts, short circuits, unrouted and empty nets, and unconnected pins by setting multiple tolerances/constraints. The detected violations can be exported for collaboration with other design systems and groups. Better yet, AutoVue can trace the path of a net or signal up and downstream from a specific component on a PCB, as well as through various PCB layers and across multiple schematic pages. This way, engineers can do things like signal matching, visualize what electrical components are supposed to do, and confirm a signal out to something is going to activate a physical action, such as solenoid.

Automotive Industry

Digital mock-up grows up: digital mock-up tools sit nicely between heavy-weight, complex CAD systems and lightweight CAD viewers. Every automotive enterprise should have one of these tools. And in time, will have one

Automotive Design & Production, June, 2007 by Lawrence S. Gould

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