Multi-Robot Navigation with EasyNav

This HowTo demonstrates how to run multiple EasyNav robots simultaneously in a shared simulation. Each robot operates independently using its own namespaced set of nodes, topics, and frames.

Overview 

Multi-robot navigation with EasyNav is straightforward, but it requires discipline when naming topics and managing TF frames. This tutorial explains how to set up multiple robots safely without topic or TF conflicts.

—

Setup 

Before starting, make sure you have followed the installation instructions in Build & Install. Then ensure that your workspace includes at least:

EasyNavigation
easynav_plugins
easynav_playground_kobuki
easynav_indoor_testcase

and that everything builds correctly:

cd ~/ros/ros2/easynav_ws
colcon build --symlink-install
source install/setup.bash

—

1. Topic Naming and TF Management (Plugin developers)

### Fully-qualified topic names

Each plugin should publish topics under its fully qualified name, which includes the node and plugin names. This prevents collisions when several robots run the same plugins.

Example (in C++):

path_pub_ = node->create_publisher<nav_msgs::msg::Path>(
  node->get_fully_qualified_name() + std::string("/") + plugin_name + "/path",
  10);

This ensures topics look like:

/r1/controller_node/simple/path /r2/controller_node/simple/path

instead of clashing on /path.

—

### TF topic remapping

Each robot typically has its own TF tree. To isolate TF data, remap the global TF topics (/tf and /tf_static) to relative ones, so they are automatically namespaced:

-r /tf:=tf -r /tf_static:=tf_static

This yields separate TF topics for each robot:

/r1/tf and /r1/tf_static /r2/tf and /r2/tf_static

Note

Do not apply this remap if both robots are designed to share the same TF tree (which is rare).

—

### Namespaced frames

If you configure a TF prefix for each system node (e.g., tf_prefix: r1), then all frames will include this prefix:

r1/map, r1/odom, r1/base_link, etc.

Example configuration snippet:

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

—

2. Launching in Simulation 

### Step 1 — Start the simulator with two robots

The multi-robot launch file spawns two Kobuki robots within the same Gazebo world:

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, adjust the command accordingly.

—

### Step 2 — Start EasyNav for each robot

Run the EasyNav system for each robot in separate terminals. Each instance uses the same parameter file but with its own namespace and TF remapping.

Terminal 1 (robot r1):

ros2 run easynav_system system_main \
  --ros-args \
  --params-file ~/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 ~/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

—

### Step 3 — Launch RViz for each robot

Open one RViz window per robot namespace to visualize each navigation stack independently:

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

You can now send 2D Goal Poses independently in each RViz instance.

—

3. Example Parameters 

Below is a complete example parameter file for two robots. Each section is namespaced (r1/..., r2/...), so the same plugins can operate without topic or TF collisions.

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

# Robot 2 (r2) - identical configuration with different initial pose and TF prefix

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

—

Tips & Gotchas 

Namespaces everywhere: Verify all relative topics (e.g., scan_raw) are correctly resolved under each robot namespace (/r1/scan_raw, /r2/scan_raw).
Avoid over-remapping: Only remap /tf and /tf_static to relative topics when each robot manages its own TF tree.
Frame references: With tf_prefix set, refer to frames as r1/base_link, r1/odom, etc.
ROS Domain IDs: If you want isolation or multiple networks, assign different ROS_DOMAIN_ID per fleet. Otherwise, keep the same domain for shared visualization.

—

With this setup, each robot runs a full EasyNav navigation stack under its own namespace, enabling coordinated multi-robot simulation in Gazebo and RViz.

Multi-Robot Navigation with EasyNav

Overview

Setup