EasyNav Stack Tutorials

Multi-robot with EasyNav

Multi-robot navigation with EasyNav is straightforward, but it requires discipline from plugin developers when naming topics and frames. In particular:

Always publish topics with fully-qualified names, prefixed by the node FQN and plugin name. This prevents collisions between robots that run the same plugins. For example:
```
path_pub_ = node->create_publisher<nav_msgs::msg::Path>(
  node->get_fully_qualified_name() + std::string("/") + plugin_name + "/path",
  10);
```
TF management is critical:
1. Each robot typically owns its own TF topics. With namespacing, that means you want /r1/tf and /r1/tf_static for robot 1, /r2/tf and /r2/tf_static for robot 2, etc. To achieve this, remap the global TF topics to relative ones (so they get namespaced): -r /tf:=tf -r /tf_static:=tf_static. Do not apply this remap if both robots are designed to share the same TF tree (uncommon).
2. Namespaced frame IDs: if you set a TF prefix in EasyNav (e.g., tf_prefix: r1), frames will be published as r1/map, r1/odom, r1/base_link, etc. Configure this in the EasyNav system node parameters:
```
r1/system_node:
  ros__parameters:
    use_sim_time: true
    use_real_time: true
    position_tolerance: 0.1
    angle_tolerance: 0.05
    tf_prefix: r1
```

Launching in Simulation

Start the simulator with two robots

ros2 launch easynav_playground_kobuki playground_multirobot_kobuki.launch.py do_tf_remapping:=true gui:=false

Note

If your launch file uses a different name, adapt the command accordingly.

Start EasyNav for each robot in a separate terminal, using the same parameter file but different namespaces and TF remaps:

# Terminal 1 (robot r1)
ros2 run easynav_system system_main \
  --ros-args \
  --params-file /home/fmrico/ros/ros2/easynav_ws/src/easynav_indoor_testcase/robots_params/costmap_multirobot.params.yaml \
  -r __ns:=r1 \
  -r /tf:=tf -r /tf_static:=tf_static

# Terminal 2 (robot r2)
ros2 run easynav_system system_main \
  --ros-args \
  --params-file /home/fmrico/ros/ros2/easynav_ws/src/easynav_indoor_testcase/robots_params/costmap_multirobot.params.yaml \
  -r __ns:=r2 \
  -r /tf:=tf -r /tf_static:=tf_static

Example Parameters

Below is an example parameter file for two robots. Each section is namespaced (r1/..., r2/...), so the same plugins can run without topic or TF collisions. Notice the TF prefix under each system_node and the filter plugins under the maps manager (correct plugin names).

r1/controller_node:
  ros__parameters:
    use_sim_time: true
    controller_types: [simple]
    simple:
      rt_freq: 30.0
      plugin: easynav_simple_controller/SimpleController
      max_linear_speed: 1.0
      max_angular_speed: 1.5
      look_ahead_dist: 0.2
      k_rot: 0.7

r1/localizer_node:
  ros__parameters:
    use_sim_time: true
    localizer_types: [costmap]
    costmap:
      rt_freq: 50.0
      freq: 5.0
      reseed_freq: 1.0
      plugin: easynav_costmap_localizer/AMCLLocalizer
      num_particles: 100
      noise_translation: 0.05
      noise_rotation: 0.1
      noise_translation_to_rotation: 0.1
      initial_pose:
        x: 0.0
        y: 0.0
        yaw: 0.0
        std_dev_xy: 0.1
        std_dev_yaw: 0.01

r1/maps_manager_node:
  ros__parameters:
    use_sim_time: true
    map_types: [costmap]
    costmap:
      freq: 10.0
      plugin: easynav_costmap_maps_manager/CostmapMapsManager
      package: easynav_indoor_testcase
      map_path_file: maps/home2.yaml
      filters: [obstacles, inflation]
      obstacles:
        plugin: easynav_costmap_maps_manager/ObstacleFilter
      inflation:
        plugin: easynav_costmap_maps_manager/InflationFilter
        inflation_radius: 1.3
        cost_scaling_factor: 3.0

r1/planner_node:
  ros__parameters:
    use_sim_time: true
    planner_types: [simple]
    simple:
      freq: 0.5
      plugin: easynav_costmap_planner/CostmapPlanner
      cost_factor: 10.0

r1/sensors_node:
  ros__parameters:
    use_sim_time: true
    forget_time: 0.5
    sensors: [laser1]
    perception_default_frame: odom
    laser1:
      topic: scan_raw
      type: sensor_msgs/msg/LaserScan
      group: points
    camera1:
      topic: rgbd_camera/points
      type: sensor_msgs/msg/PointCloud2
      group: points

r1/system_node:
  ros__parameters:
    use_sim_time: true
    use_real_time: true
    position_tolerance: 0.1
    angle_tolerance: 0.05
    tf_prefix: r1

r2/controller_node:
  ros__parameters:
    use_sim_time: true
    controller_types: [simple]
    simple:
      rt_freq: 30.0
      plugin: easynav_simple_controller/SimpleController
      max_linear_speed: 1.0
      max_angular_speed: 1.5
      look_ahead_dist: 0.2
      k_rot: 0.7

r2/localizer_node:
  ros__parameters:
    use_sim_time: true
    localizer_types: [costmap]
    costmap:
      rt_freq: 50.0
      freq: 5.0
      reseed_freq: 1.0
      plugin: easynav_costmap_localizer/AMCLLocalizer
      num_particles: 100
      noise_translation: 0.05
      noise_rotation: 0.1
      noise_translation_to_rotation: 0.1
      initial_pose:
        x: 2.0
        y: 1.0
        yaw: 0.0
        std_dev_xy: 0.1
        std_dev_yaw: 0.01

r2/maps_manager_node:
  ros__parameters:
    use_sim_time: true
    map_types: [costmap]
    costmap:
      freq: 10.0
      plugin: easynav_costmap_maps_manager/CostmapMapsManager
      package: easynav_indoor_testcase
      map_path_file: maps/home2.yaml
      filters: [obstacles, inflation]
      obstacles:
        plugin: easynav_costmap_maps_manager/ObstacleFilter
      inflation:
        plugin: easynav_costmap_maps_manager/InflationFilter
        inflation_radius: 1.3
        cost_scaling_factor: 3.0

r2/planner_node:
  ros__parameters:
    use_sim_time: true
    planner_types: [simple]
    simple:
      freq: 0.5
      plugin: easynav_costmap_planner/CostmapPlanner
      cost_factor: 10.0

r2/sensors_node:
  ros__parameters:
    use_sim_time: true
    forget_time: 0.5
    sensors: [laser1]
    perception_default_frame: odom
    laser1:
      topic: scan_raw
      type: sensor_msgs/msg/LaserScan
      group: points
    camera1:
      topic: rgbd_camera/points
      type: sensor_msgs/msg/PointCloud2
      group: points

r2/system_node:
  ros__parameters:
    use_sim_time: true
    use_real_time: true
    position_tolerance: 0.1
    angle_tolerance: 0.05
    tf_prefix: r2

Launch two RViz instances, one per namespace

ros2 launch easynav_playground_kobuki rviz_namespaced.launch.py \
  namespace:=r1 use_sim_time:=true \
  rviz_config_file:=/home/fmrico/ros/ros2/easynav_ws/src/easynav_playground_kobuki/rviz/nav2_namespaced_view.rviz

ros2 launch easynav_playground_kobuki rviz_namespaced.launch.py \
  namespace:=r2 use_sim_time:=true \
  rviz_config_file:=/home/fmrico/ros/ros2/easynav_ws/src/easynav_playground_kobuki/rviz/nav2_namespaced_view.rviz

Tips & Gotchas

Namespaces everywhere: ensure all relative topics in your parameters (e.g., scan_raw) are resolved under each robot namespace (e.g., /r1/scan_raw).
Do not over-remap: only remap /tf and /tf_static to relative topic names if each robot maintains its own TF tree.
Frames: with tf_prefix set, refer to frames as r1/base_link, r1/odom, etc.
Discovery: if you have separate networks or want isolation, consider different ROS_DOMAIN_ID per fleet. Otherwise, keep the same domain to allow shared visualization.