Voxellayer/Obstaclelayer does'nt subscribe to right topic

[NachtaktiverHalbaffe]

Please provide the following information: OS: Ubuntu 22.04 (Docker) ROS Distro: Humble Built from source or installed: Installed Package version: 1.0.3-1jammy.20230722.003833

Expected behaviour With provided configuration file the voxellayer/obstaclelayer are detecting and showing obstacles in costmaps

Actual behaviour Voxellayer (and also obstacle layer) not subscribing to right scan topic and thus not showing obstacles in costmaps. In Rviz2 its suggesting to add a /< namespace >/localcostmap/scan topic to visualization which seems very suspicious. This topic doesnt appear with my workaround when everything works as expected. I think the layers trying to subscribe to this topic to where clearly no publisher exists

To Reproduce Provide the steps to reproduce:

• Start navigation2 (occurs in both cases when running with and without namespace) with launch files and configuartion parameters provided by turtlebot_navigation package
• Wait until everything is running
• Inspect Costmap and which nodes are subscribed to corresponding scan topic => Costmaps arent subscribed to corresponding scan topic

My workaround I changed the topics of the data sources to "absolut" topics instead of ""relative" ones. A fellow student had also this issue with another turtlebot with stock trutlebot humble software (no namespacing) and this fix also helped. I provide the updated part of the config below:

local_costmap:
  local_costmap:
    ros__parameters:
      update_frequency: 5.0
      publish_frequency: 2.0
      global_frame: odom
      robot_base_frame: base_link
      use_sim_time: false
      rolling_window: true
      width: 3
      height: 3
      resolution: 0.06
      robot_radius: 0.15
      plugins: [static_layer, voxel_layer, inflation_layer]
      inflation_layer:
        plugin: nav2_costmap_2d::InflationLayer
        cost_scaling_factor: 4.0
        inflation_radius: 0.2
      voxel_layer:
        plugin: nav2_costmap_2d::VoxelLayer
        enabled: true
        publish_voxel_map: true
        origin_z: 0.0
        z_resolution: 0.05
        z_voxels: 16
        max_obstacle_height: 2.0
        mark_threshold: 0
        observation_sources: scan
        scan:
          # original: topic: scan, not working
          topic: /<namespace>/scan # working
          max_obstacle_height: 2.0
          clearing: true
          marking: true
          data_type: LaserScan
          raytrace_max_range: 3.0
          raytrace_min_range: 0.0
          obstacle_max_range: 2.5
          obstacle_min_range: 0.0
      static_layer:
        plugin: nav2_costmap_2d::StaticLayer
        map_subscribe_transient_local: true
        map_topic: /map
      always_send_full_costmap: true

I think the voxel layer isn't appending the prefixes right to the topics if using "relative" topics. Could be a nav2 issue, but I want to start reporting in this place in case you spot anything different before reporting to the nav2 project

[hilary-luo]

@NachtaktiverHalbaffe Thank you for bringing this up, I think I see your point and will look into this.

[NachtaktiverHalbaffe]

Great, keep me up to date if the have to forward the issue into the Nav2 project if its a pure Nav2-issue

Also forgot to mention that my fellow student runs it on bare metal (but also humble versions, not iron) instead of Docker, so it isnt a platform issue

[hilary-luo]

@NachtaktiverHalbaffe I have entered a ticket with Nav2 to clarify how namespacing should be handled / remapped. The content of the ticket refers to the other clearpath repos but the solution will be applied to turtlebot4 as well. Please follow along here https://github.com/ros-planning/navigation2/issues/3772

[NachtaktiverHalbaffe]

I have jumped into the github issue and also provided the things I found out during futher debugging and problem solving. Meanwhile the workaround is to specify absolute topics or use rewrittenyaml in the launchfile there these topics are rewritten to the right absolut ones