Friday, October 17, 2008

Synchronous Technology and My First Impressions

I finally got my hands on NX6 and have been able to try this so-called breakthrough in CAD technology that Siemens calls Synchronous Technology.

I first got myself back up to speed by using NX6 in its default history-based mode. And as with any history-based modeling system, it is a painful process making sure that the tree is structured properly and constrained in a useful and predictable way. And as usual once you do have a nice model created that behaves the way you want, you feel gratified. Kind of like when I solved the Rubix Cube for the first time. Highly constrained and structured models certainly have their place in product development, but conceptual design is not one of those places. And just hope that you do not have a sudden change come to you once you have this nice and highly constrained model completed.

With NX6, like many other history-based systems you do have the option to perform direct edits on geometry. This capability is provided to allow you to accommodate small unforeseen changes that may come at you without having to mess with the tree or parameters. Unfortunately these direct edits are captured in the tree so that the next time you have to regenerate the model, the changes are not lost. The end result is an even more complex and volatile tree.

So to work around all the usual issues of using a history-based system for concept design, rapid design cycles, interoperability, and so on, Siemens has introduced Synchronous Technology, which will save us all from this misery.

Siemens has claimed to introduce the next breakthrough in 3D CAD with what they are calling “Synchronous Technology”. The demos that are out there look reasonable good, as any demo should. The use model looks nice and the graphical interaction and feedback appears to be very nice.

On the contrary though, what Siemens has introduced, was in reality introduced 10 years ago when Hewlett Packard first imbedded the synchronous parametric solver from D-Cube into their product – SolidDesigner. Since then the product was moved out of HP into CoCreate, and is now part of the PTC product line. The product is now called PTC CoCreate Modeling. Siemens’ Synchronous Technology is simply a combination of history-free modeling with the D-Cube synchronous parametric solver. Exactly the same as what HP did in the late 90’s. The D-Cube solver delivers synchronous solutions to geometrical relationships like dimensional parameters, coplanar faces, concentric faces, tangent faces, parallel faces, perpendicular faces, symmetry and coincidence. This capability allows an explicit – or “history-free” modeling system to apply needed relationships/parameters to 3D points, edges, faces, features, parts and assemblies. The relationships are solved synchronously and simultaneously. It is a mature and robust technology.

There are so many terms that we are hearing and using in so many different ways, that it causes much confusion. I think marketing departments purposely try to do this to keep us in the dark. The term “parametric modeling” usually refers to history-based modeling. The problem with using this term to describe history based modeling, is that it implies that explicit modeling can’t be parametric, which is completely untrue. Fully constrained models and assemblies in a history-free environment is possible. The difference between managing parameters in a history tree versus a history-free environment is that with the history tree, parameters are solved linearly as the tree is regenerated. In a history-free environment the parameters are solved simultaneously or “synchronously”.

Another term that gets abused is “direct editing”. In most cases this describes the capability to make direct edits to geometry while in a history-based environment, as discussed above. These direct edits are capture in the history tree. They must be maintained in the tree otherwise a model regeneration would remove the edits. Don’t confuse “direct editing” with explicit modeling. They are two different things. Explicit modeling is simply modeling without a parent-child relationship (history tree).

I am a long time user of CoCreate Modeling and am now getting some good experience with ST (although no formal training). Explicit modeling requires much intelligence in the modeling system to manage connectivity with the model (topology). It can be very complex. CoCreate has spent many years on this technology to ensure that results of edits are intuitive and expected and that the model remains a solid. CoCreate is very robust and easily handles complex topology changes in the model. It also properly manages adjacent faces, blends and chamfers, even on imported geometry. On the other hand ST is VERY immature in this area. Very rarely are edits that require topology changes successful. It has no concept of recognizing blends and chamfers. It does understand tangency, coplanar, parallel and similar conditions, but again rarely does that deliver the required results. It does recognize bosses and pockets, but has a lot of limitations even with this.

ST simply does not provide enough capabilities (yet) to justify sacrificing your history tree. Just use the direct edits that are already available.

For companies that can use the flexibility that comes from explicit modeling, CoCreate is still the best choice. The choice should not be based on user preference either. The parent/child relationship is not optional with history-based modeling and it has huge impact on process. I can’t tell you how many companies I have visited over the years that have developed huge manuals to define modeling standards for their users to follow in order to structure history trees in ways that will allow for team design, leverage and reuse and predictability in the model. For some companies this is required. For others, once they understand explicit modeling, they will realize what a waste of time and effort managing a history tree is.

I am currently going through a comparison of ST with CoCreate and will post my results when complete.


Franco Folini said...

Great post. Finally someone that knows the difference between solving constraints in parallel (long time ago it was called variational approach, explored by the MIT professor D.C. Gossard).

Burhop said...

Hi Paul,

You said, "I am currently going through a comparison of ST with CoCreate".

Its probably worth pointing out the "Sychronous Technology" is a core technology not unlike D-cubed or Parasolid.

It sounds like you are really comparing NX6's "Design Freedom" to CoCreate.


P.S. I'm a product manager for Siemens. The postings on this site are my own and don’t necessarily represent Siemens PLM Software’s positions, strategies or opinions.

Paul Hamilton said...


I am using NX6 and under Insert/ Synchronous Technology/ I have selected History-Free Mode. At the top of the Part Navigator it says "History-Free Mode".

I think I read an article in CAD Insider a while ago that refered to some comments from Dan Staples about the use of D-Cube and Parasolids to make up what Siemens refers to as Synchronous Technology. The article was titled "Solid Edge Ready For Take Off".

Correct me if this is wrong, and thanks for the comments.


Burhop said...

No, you are correct.

I was just thinking it is hard to compare technologies to CAD systems. ST is really a technology used by both NX6 and Solid Edge ST and I don't know that either exposes all of ST.

Philippe said...

Hello Paul,

Really interesting. You seem to have a good know how of the market, but what do you think of SpaceClaim.
I use it and it's an unbelievable product with a very clear interface.
But it should be interesting to have your feedback on it please.

Paul Hamilton said...

Hello Philippe,

You can read my first review of Spaceclaim in a later article on this blog. I actually wrote that about a year ago. I haven't used it too much since then. I do like the user interaction, use methods and UI. They have done a great job with that.
They do have some of the usual issues with managing complex geometry and topology though.
I just posted a comment about some work I did with Spaceclaim last night on Check it out. In general I was a bit disapointed with what I found.
It all goes back to face selection capabilities, transformation methods and predictable results.

rahul said...

Hi Paul,
It's strange that I thought exactly the opposite of what u have put down on working with Cocreate and Solid Edge ST. For me, solidedge ST managed recognition quite well while cocreate faced problems on many imported models.
( though I must admit i have used both only for evaluation and am not an expert)

Paul Hamilton said...

It is good to hear your perspective as it sounds like you have equal experience with both, although it may be limited. Due to my long experience with CoCreate, I probably automatically know my way around, where as with ST I am still leraning.
With ST, it does seems to recogonize blends on import automatically. With CoCreate you have to specifically tell it to recogonize blends. It seems that you would always want blends recogonized so I like that ST does that. Although I am not sure how robust the recogonition is.

It would be interested to know what kind of problems you saw with CoCreate.

Thanks for the comment.