Velodyne sees obstacles when there are none

[Rodolfo]

I'm using the Ros2 launch file for vlp16 on the robot, without the rtabmapviz portion. The point cloud treatment and odometry seems very good. This robot has Jammy and Humble and Nav2. The robot is beginning to do waypoint following and driving on his own. However, sometimes the Nav2 program is making black dots, as obstacles, appear where there were none on the map provided. The map area was clean white. The floor is carpet, and apparently the laser is seeing something? It's a Velodyne puck, and I understand only one scan laser is in use in Nav2, of the 16 in the unit. Is there a setting I can adjust to stop the mapping/navigation from finding and developing these obstacles in robot's way? Can I set rtabmap to do localization only? Or is it a Nav2 routine that makes new obstacles in the map?

[matlabbe]

Do you have screenshots or a database to share? The rtabmap's VLP16 launch file is doing 6DOF lidar SLAM, but no occupancy grid is produced (RGBD/CreateOccupancyGrid=false). You may set RGBD/CreateOccupancyGrid=true, though more tuning about Grid parameters would be required for your case. You may try to compare with this ros1 example with husky, which I show a robot setup with VLP16: follow this example minus RGBD camera and wheel odom guess.

If you didn't set RGBD/CreateOccupancyGrid=true, you may have started another SLAM with nav2, which is the one you are seeing creating the occupancy grid.

It is possible to set rtabmap in localization mode only (Mem/IncrementalMemory=false, and remove '-d'), however you need also a camera so that rtabmap can globally localize in the map (without camera, a workaround would be to send a initial pose topic to rtabmap).

For rtabmap and nav2 integration, you may look at those examples: https://github.com/introlab/rtabmap_ros/tree/ros2/rtabmap_demos/launch

cheers,
Mathieu

[Rodolfo]

I am using Slam Toolbox with Rviz on the laptop when mapping.

When doing localization, I start the whole nav2 stack (on the laptop) but haven't seen Slam toolbox come up.

Setting the initial pose with Rviz is no problem, I usually do that anyway.

You gave me several things to work with; thanks, I'll see what I can do!