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SLAM gmapping, what rotates/ transforms the map?

asked 2012-06-19 08:35:52 -0500

IFLORbot gravatar image

updated 2014-01-28 17:12:43 -0500

ngrennan gravatar image

Basically, I'm implementing a grid of RFID tags on the floor. The Turtlebot drives over each during mapping and assigns each a location based on base_footprint. HOWEVER, the SLAM gmapping algorithm sometimes updates the Map and rotates it, making my tags now in the wrong location. I was wondering what transform causes this rotation so I can apply the same function to my list of tags, hopefully updating them as well. It's not necessarily a problem, as once the map is actually built, I can run over the out of place tags again and update them, but I would like to not have to do this.

I'm running electric.


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Thanks dornhege. That's the answer I was looking for (the second one, I had my points in the /map frame). I didn't think there would be an easy solution, like applying the same update to my tag list that was applied to the map. I'll look into graph mapping.

IFLORbot gravatar image IFLORbot  ( 2012-06-20 03:23:23 -0500 )edit

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answered 2012-06-19 23:47:49 -0500

dornhege gravatar image

First, your tags should be positioned in the /map frame. Then at least the current position should always match. Maybe that is what your were looking for.

For earlier positions this can also work, but gmapping does not only transform the map, but actually might update the whole map to a new (better matching) one that can be distorted from a previous map arbitrarily. Depending on how stable gmapping works in your environment, you might be out of luck for a simple solution.

In that case, you can either try to recognize the relative position in the map environment or you need to switch to something like graph mapping and attach your tags to nodes in the graph.

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Asked: 2012-06-19 08:35:52 -0500

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Last updated: Jun 19 '12