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Manufacturing

Siemens PLM Charts New Course

30 Apr, 2008 By: Jeffrey Rowe

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New Synchronous Technology will bring non-parametric, non-history-based modeling to NX, Solid Edge.

Last week, Siemens PLM Software announced a new approach to CAD software that it calls the biggest MCAD breakthrough in a decade: Synchronous Technology, a form of non-history-based design. That's a pretty heady claim, and one that won't get real support until the company discloses details about the new methodology in May. The announcement was more a teaser than a demonstration, but nonetheless, the concept and its implications were intriguing. (For an overview of the Siemens announcement last week, refer to "Siemens Breaks Free from History," by Cadalyst's Kenneth Wong.)

Synchronous Technology will be integrated into the next versions of Siemens NX and Solid Edge, shipping sometime this summer. With this move, Siemens PLM Software is the latest MCAD company to jump on the bandwagon purporting the advantages of non-history-based design.

Mechanical CAD 101
Before we examine Synchronous Technology, I'd like to take a brief look at the MCAD technology that preceded it: direct modeling -- or really, direct model editing. Here, modeling is free of history as parametric constraints. Direct modeling has been offered in other CAD applications for a few years, including IronCAD, SpaceClaim, and those from Kubotek (formerly Cadkey) and CoCreate (now part of PTC) -- as well as UGS (now Siemens PLM Software) with NX 5, which, interestingly, offers both history-based and non-history-based design approaches.

History-based parametric modelers -- such as SolidWorks, PTC's Pro/ENGINEER, and Autodesk Inventor -- have dominated the MCAD market since the late 1980s. This methodology creates and maintains a record of how a part model is built, using a history tree to track and replay 2D profiles and modeling steps for generating and modifying 3D geometry. When parameters in a model are changed and the model is regenerated, the CAD application repeats the operations from its history, using the new parameters, to create a new part model. The main drawback is that each step in the history depends on the profile and modeling step that came before it. The more complex the model, the more complex the history -- and the more complex editing becomes.

As a result, as noted previously, an increasing number of parametric modeling developers in the past couple of years have hopped on the non-history-based bandwagon. A non-history-based approach lets you make changes late in the design process, unbound by the constraints and complications that a history tree can impose. A non-history-based system can make data import easier because you don't have to worry about computational overhead and the burden of dealing with a history tree from a different system. 3D model data can be imported from just about any source for editing without the need for a translator/converter -- a major bonus in a multi-CAD environment.

Some users accustomed to working with parametric, history-based systems might be uncomfortable with the absence of the history at first. However, I think that many users will appreciate the shorter learning curve and the faster changes that can be made to a design when you don't have to deal with its history.

This brings us to the fact that in some cases, parametric modeling -- history based or not -- is not necessarily the best choice. A history-free architecture means you can more easily change the 3D model without knowing how the design was originally created. You need not understand a design's constraints, parametrics, or history-based feature tree if you want to change or reuse data. You can import and use geometry directly, as though it were virtually native data, and without conversion or translation. This is what makes the new Synchronous Technology unique. And as far as I know, it is the first-ever non-parametric, non-history-based MCAD solution.

Details Sketchy
After Siemens PLM Software announced Synchronous Technology, I followed up with the company and asked if this was an extension of the non-history-based design methods that were introduced in NX 5. Paul Brown, director of NX marketing, said, "Synchronous Technology extends the concepts of direct modeling interaction (in the next versions of both NX and Solid Edge), while now operating in a non-history-based environment, plus adding constraint-driven techniques.

"Synchronous technology significantly expands on what we began in NX 5 by adding a new ability to infer the intent behind the geometry. Geometric conditions such as tangency, coaxial, coplanar are all inferred and, if desired, maintained during the editing of the design.

"In addition to this, synchronous technology introduces new approaches to editing the geometry, such as dimension-driven editing and section-based editing. Dimension-driven edits add intelligence exactly where needed on the model, adding 3D dimensions to the design that can drive geometric changes and form the basis of adding logic to a nonparametric design if required. Section-based editing increases the flexibility a designer has, allowing a 2D cross-section generated through the design on the fly to drive changes in the design."

I also asked if Synchronous Technology could be toggled on and off, depending on whether a user wants or does not want to employ it, thereby increasing the systems' versatility. Dora Smith, director of PR for Siemens PLM Software, said the company could not respond at this time because the answer gets into how the technology will be implemented in each product, which won't be rolled out until the May 20 launch of NX 6 and Solid Edge with Synchronous Technology.

The synchronous in Synchronous Technology comes into play because the new technology intends to synchronize engineering relationships, features, and parameters via a more direct model creation and editing paradigm. Another way to look at this is that Synchronous Technology will synchronize feature recognition and constraint solving with geometry and topology. Although NX has had direct editing capabilities, Synchronous Technology will sit on top of that, apply constraints, and impart design intent -- taking it to the next level.

Synchronous Technology can be applied to portions of models or entire models and will let you import features, such as bosses, from other MCAD systems, such as Pro/ENGINEER and CATIA. Relationships and constraints of these imported features are inferred by Synchronous Technology and can be treated as if originally created in NX. This is a new twist on feature recognition because, according to the company, any boundary representation (b-rep) data that can be extracted can be used with Synchronous Technology. This could prove to be the most valuable benefit of Synchronous Technology for most users -- making it easier to function in multi-CAD environments.

Looking Ahead
Synchronous Technology sounds promising, but does it mean that history-based, parametric modeling will go away? No. A history-free design approach can provide some surprising benefits, but the history-based, parametric paradigm will not disappear. However, the non-history-based paradigm does work especially well with pure geometry. Maybe a better way to go is "parametrics on demand," in which that approach would be available to the user if needed, but it remains to be seen if that's the route Siemens PLM Software will take with the next versions of NX and Solid Edge.

Many of us realize the benefits of history-based methods, but they aren't best for every job, and a growing number of vendors are thinking along the same lines.