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Why robot_model use urdf not just using universal CAD extension file?

asked 2011-07-20 04:12:55 -0500

sam gravatar image

updated 2014-01-28 17:10:04 -0500

ngrennan gravatar image

Because translate from CAD file to urdf will lead to a lot of steps or problems.

I have occurred some.

I am afraid of that maybe also cause some precisions problems during translation.

Is there any way just read the file from Inventor,Solidworks,Proe...?

Or is it possible in the future?

Thank you~

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answered 2011-07-20 04:23:37 -0500

dornhege gravatar image

URDF contains more information that CAD files, i.e. it is more universal. You can, however, use models imported from CAD programs in the URDF.

Extra things that are handled are e.g. kinematics, joint limits (those might be in CAD programs), extensions for simulation, collision models.

Also a URDF is very small to read if you don't care about the CAD models.

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What you mean is URDF contain all the information of CAD files,and also contain with other features that CAD files don't concern? And is there any possible lose from transfer CAD files to URDF?
sam gravatar image sam  ( 2011-07-20 04:31:25 -0500 )edit
I'd say it depends on the format. Regarding your question the word "Unified" is the most important from the URDF. You can attach meshes (i.e. CAD models) to the URDF, but information like materials, screw threads, etc. will be lost.
dornhege gravatar image dornhege  ( 2011-07-20 04:36:18 -0500 )edit
And........if URDF is more universal,why CAD software couldn't export to that extension? Is URDF a different type of purpose,so CAD software just ignore that?
sam gravatar image sam  ( 2011-07-20 04:39:32 -0500 )edit
So information like materials, screw threads, and etc are not important with gazebo,right?
sam gravatar image sam  ( 2011-07-20 04:42:16 -0500 )edit
I think theoretically CAD software could export URDF, but it is not widely used enough to be on their radar. Plus its not just one piece of CAD software.
David Lu gravatar image David Lu  ( 2011-07-20 05:07:28 -0500 )edit

answered 2011-07-20 04:51:57 -0500

David Lu gravatar image

The simmechanics to urdf tool is one way to get data from CAD programs to ROS.

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Asked: 2011-07-20 04:12:55 -0500

Seen: 1,768 times

Last updated: Jul 20 '11