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map frame and odom frame are not in one point, if i fix one frame the other keep moving

asked 2021-02-28 14:12:29 -0600

Momit gravatar image

hello everyone , I am trying to make my own robot by modifying summit_xl robot. when i launch tf in rviz map frame and odom frame are not in one point, if i fix one frame the other keep moving. I don't know what is the problem :(

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answered 2021-03-01 08:17:01 -0600

updated 2021-03-01 08:20:17 -0600

How is the transformation build up?

Most of the time the map->odom transform is build by SLAM or pure Localization. This is most likely the cause for your movement.

Why should both frames even be fixed? This would imply that you 100% trust your odometry source. This is almost never the case other than in perfect simulation, since you will have things like wheel slip on your robot that will have an impact on your odometry.

That said, if you trust your odometry then there is either no need for the map or for the odom frame you can just publish your map on odom or your odom data straight to map.

This answers is purely based on guesses on your system. If you want precise information you'll need to supply more information about it, maybe a picture of your tf_tree and a tf_graph so we know what exactly is going on.

Btw. The odometry frame is a continuous frame, where as the map frame is a discrete frame, meaning the transform between map and odom gets calculated in increments and the transform will jump often. As with most questions about TF i recommend REP 105 this is a strict definition how the tf tree is supposed to be set up.

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Thanks for your answer, yes the transform was published by slam gmapping. The problem was the transform was both published by gmapping and amcl, and don't know why they were publishing different transform. As I am launching both amcl and gmapping same time by launch file so the problem was happening. Launching only gmapping solved the problem for now :)

BTW can I add you on any social media like Facebook, Instagram or discord?

Momit gravatar image Momit  ( 2021-03-01 11:05:02 -0600 )edit

No problem. I'd rather not share my private accounts here. If you want you can share your discord name and handle and i'll add you, although i can't promise that i can help you with everything.

Tristan9497 gravatar image Tristan9497  ( 2021-03-01 12:24:43 -0600 )edit

Did you find any solution ?

tomkimsour gravatar image tomkimsour  ( 2021-05-18 01:41:07 -0600 )edit

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Asked: 2021-02-28 14:12:29 -0600

Seen: 1,559 times

Last updated: Mar 01 '21