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Gmapping Error : No map received [closed]

asked 2018-10-28 13:28:43 -0500

jawsqb gravatar image

updated 2018-10-29 09:00:22 -0500

Hey!

I am attempting to implement gmapping into my gazebo rover simulation.

I am receiving laserscan data fine , however when starting gmapping node I am not getting any map building in rviz. I am also getting an additional warning : "No map received"

My tf tree seems fine at: map > odom > base_link > ...

I am new to ROS, I believe there might be an issue with the transforms?

Here are pictures of my system:

https://imgur.com/a/ddZSjhl

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Closed for the following reason the question is answered, right answer was accepted by allenh1
close date 2018-10-31 15:51:58.700826

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This is not enough information to help you. Please provide details on where the warning is coming from (I'm guessing rviz?), as well as the output of rosrun tf view_frames (or equivalent).

mgruhler gravatar imagemgruhler ( 2018-10-29 02:11:40 -0500 )edit
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Not a whole lot of info in the question. You say you are "receiving laserscan data fine", so I would start there. With all your nodes running do rostopic info /your_laserscan_data_topic. If the mapping node is not listed as a subscriber you need to remap the topic in the mapping launch file.

Reamees gravatar imageReamees ( 2018-10-29 02:32:32 -0500 )edit

I am very sorry for low detail, the website wasn't letting me post pictures due to being a new account.

https://imgur.com/a/ddZSjhl

I have attached pictures of issue as well as the rostopic info ...

I do seem to have my gmapping node subscribing to laser scan.

thank you!!

jawsqb gravatar imagejawsqb ( 2018-10-29 08:56:13 -0500 )edit
1

most of the interesting output in the images (except of the rviz image) is just terminal output. You coudl have copy'n'pasted that into your question (obviously, formatting it as code with the button showing 010101)

mgruhler gravatar imagemgruhler ( 2018-10-29 10:52:08 -0500 )edit

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answered 2018-10-29 10:51:10 -0500

mgruhler gravatar image

Judging from the images you posted, gmapping is subscribing to /dd_robot/laser/scan.

BUT there is no publisher on this topic. Thus gmapping does not get a scan. Doublecheck what you subscribe to in rviz to actually get the scan.

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Thank you!! I reevaluated my gmapping launch file, and my hokuyo laser gazebo plugin.

Turns out the gazebo plugin was publishing to robot/laser/scan while my gmapping was subscribing to dd_robot/laser/scan.

jawsqb gravatar imagejawsqb ( 2018-10-30 12:43:40 -0500 )edit
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answered 2018-10-29 14:54:36 -0500

Reamees gravatar image

updated 2018-10-29 14:59:13 -0500

Ros deffinetly has a bit of a learning curve and it might be confusing what would be useful info for debugging and what info would be neccasary to help you solve your issue. The problem you are having is not being very familiar with the tools within ros.

There are recources like https://answers.ros.org/questions/ask/ for info about how to go about asking questions here. There are also resources a bit of googling away, one example, that go a bit more in depth about debugging nodes.

It's also handy to keep some form of a ROS cheat sheet around until you feel more comfortable around ROS, something like this for example.


As for the current question it is not quite possible to determine the problem from the info in the pictures. rostopic info /dd_robot/laser/scan output gives you a hint. The topic is being subscribed to by gmapping, but there are no publishers to the topic. You need to remap the gmapping topic to subscribe to whatever is publishing the the laser scan data you are visualizing in rviz.

http://wiki.ros.org/Remapping%20Arguments

http://wiki.ros.org/Remapping%20Arguments

roswtf, rosnode list, rosnode info your_node, rostopic list, rostopic info your_topic, rosrun rqt_graph rqt_graph are just a few of the commands that should help you trace the problem down deep enought so that people can help you better.

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Thank so much for the resources provided!! I will certainly keep them handy. Thanks again for understanding for me being new.

I will definitely keep in mind on providing more concrete information next time!

jawsqb gravatar imagejawsqb ( 2018-10-30 12:39:36 -0500 )edit
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answered 2018-10-30 12:43:52 -0500

jawsqb gravatar image

Turns out the gazebo plugin was publishing to robot/laser/scan while my gmapping was subscribing to dd_robot/laser/scan.

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Asked: 2018-10-28 13:28:43 -0500

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Last updated: Oct 30 '18