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Why transform has to be broadcasted periodically?

asked 2016-05-26 06:09:05 -0500

Kay Park gravatar image

Hello,

Nowadays I am trying to build a mobile robot with several sensors, and be curious about using relative positions of sensors in ROS.

In several tutorials, every transform(in my case, sensors) must be broadcasted periodically even if they are static in the whole robot configuration; Assuming that the base link and the relative position of sensors will not be changed.

Is there any specific reasons to this? I couldn't find any documents or explanation to this. I think it is kinda waste of resources.

Thank you in advance.

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answered 2016-05-26 06:39:13 -0500

updated 2016-05-26 09:13:24 -0500

NEngelhard gravatar image

In the original tf implementation you are correct; even transforms that don't change over time need to be constantly re-broadcast. This does indeed waste bandwidth and can lead to unnecessary exceptions being thrown. This was just a design oversight that was addressed with the release of tf2. tf2 introduces the tf_static topic to fix exactly the issue you are describing. Many of the tutorials on the wiki are still using the tf API and functionality, and should likely be updated (remember, it is a wiki that supports community editing).

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Thanks a lot for your detailed answer, appreciate it. :)

Kay Park gravatar image Kay Park  ( 2016-05-26 06:44:41 -0500 )edit

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Asked: 2016-05-26 06:04:00 -0500

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Last updated: May 26 '16