Fix simulation errors

[Uyên Lê Thị Thu]

I'm a new user of Linorbot2. I've just started scanning maps but I'm encountering the problem shown in the image. Could you please take the time to help me fix this error? Thank you very much.

Sincerely,
from Vietnam

[Pito Salas]

What is the problem you are seeing? The colored lines show where the simulated lidar is hitting walls. The reason they are floating in the air is that the distance you have in your urdf between the “floor” and the lidar is too large. Is that it?

Best,

Pito

Boston Robot Hackers &&
Comp. Sci Faculty, Brandeis University (Emeritus)

> On May 30, 2026, at 4:49 PM, Uyên Lê Thị Thu <uyen....@gmail.com> wrote:
>
> I'm a new user of Linorbot2. I've just started scanning maps but I'm encountering the problem shown in the image. Could you please take the time to help me fix this error? Thank you very much.
>
> Sincerely,
> from Vietnam
>

> <5a648253b462353c6c73.jpg>
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> <5a648253b462353c6c73.jpg>

[Kim Olesen]

Laser looks like lidar is rotated 180 degrees. Find your urdf file, set the yaw in laser pose to 3.14159. run colcon build again and source..

To view this discussion visit https://groups.google.com/d/msgid/linorobot/64576768-1002-40FF-BEAA-08D0C6CC2DFA%40gmail.com.

[Paul Bouchier]

If you want to post your issue in Issues or Discussions in the Linorobot repo at https://github.com/linorobot/linorobot2 we can have a more detailed discussion. There's documentation on how to launch simulation at the web page here: https://linorobot.github.io/linorobot2

You should have launched it with 

ros2 launch linorobot2_gazebo gazebo.launch.py spawn_x:=0.5

To me, it looks like you may have driven the robot into one of those pillars in turtlebot_world and it lost odometry localization.

But I'd need to know how you launched it and what you did to get it in that state.

Paul

To view this discussion visit https://groups.google.com/d/msgid/linorobot/CABfcQv_J%2B%2BzKf1LMWLvjJXkJXosium7Zb6ManRZjq-RaCPu1Wg%40mail.gmail.com.

[Pito Salas]

Just going back to the OP: what exact problem were you seeing that you were concerned about? What looks wrong?

Best,

Pito

Boston Robot Hackers &&
Comp. Sci Faculty, Brandeis University (Emeritus)

> To view this discussion visit https://groups.google.com/d/msgid/linorobot/CABfe6oRtTuqpOpqqmuhZzo_9_bANO%3DmAsh%2B9kxg-Drt2Ocg_TA%40mail.gmail.com.

[Charles de Montaigu]

Four months ago Juan Miguel removed the default x spawn value. LinoRobot is spawn inside the center pillar of the turtleBot3 World.

Paul's ROS2 launch parameter should do the trick. we probably need to update the Readme section Simulated Robot - ReadMe specifying the difference spawn location based on World selection ?

As well, I keep the sequence order of the terminal when launching (i.e TerminalStart Gazebo) simulation with 2 Terminals otherwise i see weird stuff in terminal 2 Navigation output log.

Looking at the Readme for the Simulation section Terminal 2

Terminal 2:Run SLAM or navigation (same commands as physical robot, add sim:=true):

# Slam

ros2 launch linorobot2_navigation slam.launch.py sim:=true
# Navigation
ros2 launch linorobot2_navigation navigation.launch.py map:=<path_to_map>/<map_name>.yaml sim:=true

As mentioned we need this thread content to be in the Discussion Section of the Linorobot2 github and reference back with a link to this email. As well, Add both output logs as attachments to the discussion entry item for proper subsequent debugging.

Thanks,

Charles

To view this discussion visit https://groups.google.com/d/msgid/linorobot/CABfe6oRtTuqpOpqqmuhZzo_9_bANO%3DmAsh%2B9kxg-Drt2Ocg_TA%40mail.gmail.com.