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Required tf Transforms in gmapping

asked 2011-07-30 02:42:04 -0500

sam gravatar image

updated 2011-07-30 12:45:50 -0500

tfoote gravatar image

In gmapping documents http://www.ros.org/wiki/gmapping , and in 5.1.5,5.1.6 says that base_link → odom, and map → odom.

I have try to use map → odom → base_link → base_laser.

  1. I don't know "base_link → odom" is right or "odom → base_link" is right? Why?

  2. What's the transform formula between odom and base_link?

  3. Can I output the transform data(map→odom) from gmapping?

Thank you~

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answered 2011-07-30 07:30:21 -0500

dornhege gravatar image
  1. odom -> base_link. You are building a tree starting from a fixed frame and going down the attached things.

  2. What do you mean with formula? It should be the robot's motion estimation.

  3. Do you mean output for debugging or generate? For the former use tf_echo (or display in rviz), for the latter: Yes, that's what it's supposed to do.

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Why my gmapping node doesn't require /odom? Doesn't Gmapping need to know the position of robot or laser range finder?
sam gravatar image sam  ( 2011-07-31 20:15:47 -0500 )edit
I haven't written the package, but I would say that it gets the data from the odom->base_link transform and the motion model is "hardcoded" as gmapping params (instead of using the covariance).
dornhege gravatar image dornhege  ( 2011-08-01 00:15:16 -0500 )edit

What could be the reasons of empty map.pgm although it's size is 15.3 MB. Now laser messages are properly published and the tf tree looks ok. But no transform from [/GrndTruth] to frame[/map] and no transform from [/base_GrndTruth to frame[/map]. You can view in details http://answers.ros.org/question/94671/error-in-creating-2d-global-map-of-the-environment/

RB gravatar image RB  ( 2013-11-13 18:49:44 -0500 )edit

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Asked: 2011-07-30 02:42:04 -0500

Seen: 1,410 times

Last updated: Jul 30 '11