Issue with Creo Assembly Import: Control Point Misalignment Due to Translation Offset in Simscape

I'm importing a PTC Creo assembly into Simscape to model dynamic motion. In Creo, I defined a control point that I want to use to drive the position of the entire assembly. This point is defined relative to a fixed reference point.

To enable this in Simscape, I created a dummy block in Creo and added a planar connection so that Simscape would generate a Planar Joint at the control point. The import completes successfully, and the model shows up in Simscape with the correct structure.

There's a problem: the control point appears at the reference point location instead of where it should be. I found that I can fix this manually by going into the Transform block associated with the dummy component and changing the Translation setting from TranslationCartesianOffset to TranslationNone(Picture below) Once I do this, the control point moves to the correct position.

My question: Why does the control point default to the reference point location in Simscape, and is there a way to automatically preserve the offset during the import process?

Answer 1

[Jacob Mathew]

Hey @Shumirai,

I tried replicating this behavior using the Import a CAD Assembly Model example. You can open this example by running the command below:

openExample("sm/ImportedCADModelExample");

When running the example to import the Robot CAD Assembly using the smimport function, it uses a Rigid Transform block as you have shown. Here too, the block parameters of Rigid Transform show that under the Translation section, the Method is set to Cartesian and the corresponding Offset is the value smiData.RigidTransform(25).translation

However, if I double click and add the block manually, it defaults to None for the Translation Method property. This is in correspondence with the documentation as well, where None is the default value for the Translation Method Property. You can reference it below:

https://in.mathworks.com/help/releases/R2024b/sm/ref/rigidtransform.html#mw_0ae4a5b6-3b22-4f46-8cdc-9a176dd7a9e9

It looks like when the CAD file being imported has specific metadata related to Translation and Rotation, MATLAB auto populates the necessary parameters with those values.