Is there a way to subscribe to tf data?

asked 2011-10-27 03:05:20 -0500

sebsch
780 ●13 ●14 ●17

updated 2011-10-27 03:12:41 -0500

Up to now, I have used tf as described in the tutorial Writing a tf listener: Whenever I need some positions transformed, I just use lookupTransform.

I am considering using tf data to control a robot and would like the robot to react whenever new tf information becomes available, i.e. subscribe to tf data. Is this possible at all?

The only possible way I see at the moment is having a polling loop as shown in the tutorial. This is bad because it introduces latency (especially if I choose a low rate) and wastes cpu time (especially if I choose a high rate).

Is there really no different option?

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I'm interested in this as well. So far I used a workaround - publishing a on dummy topic every time I publish a new tf. Then I subscribe to the dummy topic and use it as a trigger to lookup the tf.

Ivan Dryanovski ( 2011-10-27 03:17:07 -0500 )edit

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answered 2011-10-27 03:43:21 -0500

AHornung

5904 ●43 ●74 ●102 http://www.informatik....

There is a topic "/tf" where tf information is published on as type tf/tfMessage (which contains the actual transforms). Why not subscribe to that? All tf information will be published on that topic however, so you may have to inspect the messages and only trigger your control on the right transforms.