[URDF files] Covariance in joint definition and/or metadata

asked 2018-04-06 02:20:17 -0500

Arv gravatar image

Hello everyone,

I have a question about the .urdf file format. Is it possible to associate a covariance matrix to a joint transform (more specifically a 6x6 matrix).

After searching I didn't found something like this, but in this case is it possible to associate general metadata to a joint ? (or for that matter any way of putting metadata in a .urdf readable by the urdfdom parser ?).

I am using urdfdom to parse the files in a c++ environment.

Best Regards.

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You can add arbitrary XML to urdfs, but I don't believe the parser will map those to C++ objects (it can't really at the moment, it doesn't have a type for it). Retrieving that info would then be done by using a plain XML parser and feeding it robot_description.

gvdhoorn gravatar image gvdhoorn  ( 2018-04-06 02:29:05 -0500 )edit

As to covariances: no, there is no support for that right now in urdf. It's not one of the standardised elements.

I assume you are feeding the (parsed) urdf to a solver of some kind? TF does not support the concept of uncertainty right now. There are some pkgs that add this, ..

gvdhoorn gravatar image gvdhoorn  ( 2018-04-06 02:30:32 -0500 )edit

.. like uncertain_tf, but this is not uniformly supported by other urdf consumers.

gvdhoorn gravatar image gvdhoorn  ( 2018-04-06 02:30:51 -0500 )edit