No laser scan received amcl localization

Course Support ROS Navigation In 5 Days
1

I am working on the course project for navigation in 5 days, section II localization.
When launching the launch file I get the error No laser scan received. Verify that data is being published on the /scan topic.
When I check rostopic echo /scan it does return anything,
rostopic info /tf returns
Publishers:

  • /amcl (http://3_xterm:33481/)

Subscribers:

  • /amcl (http://3_xterm:33481/)
2

Are you running the right simulation with a laser scan?

If so, check for the right scan topic. It’s not necessarily /scan.

rostopic list
3

I checked and /scan is running

4

What does rostopic info /scan say and can you paste the output of rostopic list here?

5

Ok, so rostopic info says:
Type: sensor_msgs/LaserScan

Publishers: None

Subscribers:

  • /amcl (http://2_xterm:41975/)

and rostopic list:
/amcl/parameter_descriptions
/amcl/parameter_updates
/amcl_pose
/diagnostics
/initialpose
/map
/map_metadata
/particlecloud
/rosout
/rosout_agg
/scan
/tf
/tf_static

6

Okay, so nothing is publishing to the /scan topic, that’s why you are getting that error. It’s the simulation (Gazebo) that publishes to it. Also, I see no Gazebo topics in the rostopic list, so the simulation is not running.

Have you started the simulation? You should have the following running in another terminal or have the launch file for your localization package start it automatically.

roslaunch realrobotlab main.launch
7

Thank you so much for your help. Starting the main.launch file solved the problem.

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