Hello,
I am facing an issue with the /scan topic and wanted to check if this could be a platform or environment problem.
I am working on the 3rd Part of the Real Robot Project (Wall Finder - Wall Follower - Odom Recorder) project. The exact same code was working fine yesterday on: Simulation, Real robot.
I ran multiple full laps successfully without changing the logic.
But today, the laser scan is not returning anything for the real robot (it is working fine in simulation though).
The /scan topic exists:
ros2 topic list | grep scan
/scan
Topic information looks normal:
ros2 topic info /scan
Type: sensor_msgs/msg/LaserScan
Publisher count: 1
Subscription count: 2
However, no data is received:
ros2 topic echo /scan
# (no output)
As a result, nodes that depend on LaserScan (e.g. wall_finder) remain stuck printing:
Waiting for scan...
What I’ve Already Checked:
- Verified QoS compatibility (RELIABLE / BEST_EFFORT on both publisher and subscribers)
- Confirmed the same behavior in:
- Simulation
- Real robot
- Restarted nodes and launch files
- No code changes between the working and failing runs
This makes it appear that the LaserScan publisher node is alive but not actively publishing data.
Is this a known issue with the real robot platform where the laser node can start without publishing data? Is there some issue ongoing with the platform?
Are there recommended steps to force a clean restart of the LaserScan publisher ?
Thanks in advance, and please let me know if additional diagnostics would be helpful.
For the Construct Staff:
I have my project presentation scheduled in approximately 3 hours.
Everything was running smoothly until today morning, and I also have recorded videos showing successful runs from earlier.
Given the circumstances, would you recommend postponing the presentation if the issue persists?
Best,
Ninad Mehta