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Using slam_gmapping for an extern simulator

asked 2015-06-12 02:16:08 -0500

GG31 gravatar image

Hi,

I have my own simulator and I would like to use slam_gmapping package. I understood that I have to publish to two topics /scan and /tf. I understood the data sent to /scan, but /tf is a transformation, I understood how tf works with the ros tutorial but what data, transformation are expected ? a frame_id and a child_frame_id are requiered for each message. How can I decide which frame I need ? How to build the tree ? I saw that may be a basic tree is map -> odom -> base_link but which correspond to what ? I tried to publish to /scan and /tf but the gmapping doesn't initialize at all and answers me with a warning : I tried to figure it out, but I am a little desperate now. What did I miss ?

Thank you,

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answered 2015-06-16 02:05:23 -0500

GG31 gravatar image

To answer to myself, slam_gmapping works with the clock, that means you have to publish to /clock, if not, nothing happens. Now, /tf of /map->/odom publishes 000 and 0001 for the rotation, but when I use slam_gmapping, it publishes nan values only. I think it is related to the first frame who has nan values : update ld=-nan ad=nan Laser Pose= -nan -nan -nan But I don't know why. What is ld? Laser Pose? How can I change this values?

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You do not have to publish the clock! This is supposed to be the real time of the system and only published by simulation.

dornhege gravatar image dornhege  ( 2015-06-16 03:28:06 -0500 )edit
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answered 2015-06-16 03:30:20 -0500

dornhege gravatar image

You need to provide the /odom -> /base_link transformation, which has to correspond to your robot's odometry. You never want to send /tf message directly. Use a TfBroadcaster instead.

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Thank you for your answer, but in this case, there is no initialization of slam node at all and answers this warning : [ WARN] [1434521368.489624858]: MessageFilter [target=odom ]: Dropped 100.00% of messages so far. Please turn the [ros.gmapping.message_notifier] rosconsole logger to DEBUG for more

GG31 gravatar image GG31  ( 2015-06-17 01:12:32 -0500 )edit

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Asked: 2015-06-12 02:16:08 -0500

Seen: 68 times

Last updated: Jun 16 '15