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Why does robot_state_publisher skip publishing fixed joints

asked 2011-10-25 11:15:31 -0500

When attempting to do transforms on a kinematic model managed by robot_state_publisher I've noticed that fixed joints do not get published along with the tf data produced by publishTransforms.

This causes problems in anything relying on the transform chain like, among other things, rviz.

Why does this happen?

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answered 2011-10-25 11:15:50 -0500

updated 2011-12-12 07:03:55 -0500

It turns out as of Electric, the semantics of publishTransforms have changed and there is a separate call to publish fixed joints/transforms:

  • publishFixedTransforms

Change happened here: https://kforge.ros.org/robotmodel/robot_model/rev/5a3604a9031f

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This allows you to not publish the fixed transforms as fast as the dynamic ones, saving bandwidth.
tfoote gravatar image tfoote  ( 2011-12-12 06:31:31 -0500 )edit
That makes sense, but the semantics seem to have changed from diamondback to electric with no change in signature/warning. That would cause silent failure in code written to the old semantics. Not sure if it makes sense to file a ticket now, as any fix would cause a second semantic change. Opinion?
Asomerville gravatar image Asomerville  ( 2011-12-12 06:53:26 -0500 )edit
When you use the robot state publisher as a ROS node, the functionality should not have changed, and all old code should still work. If you are using the internal API of the state publisher, then this is indeed a breaking change.
Wim gravatar image Wim  ( 2011-12-12 09:16:25 -0500 )edit
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I got the impression from the wiki/tutorial that library was meant for end users/counts a public API. Not so?
Asomerville gravatar image Asomerville  ( 2011-12-12 09:35:47 -0500 )edit

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Asked: 2011-10-25 11:15:31 -0500

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Last updated: Mar 28 '12