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Nav2 Integration

FusionCore is a drop-in odometry source for Nav2. It publishes everything Nav2 needs out of the box.

FusionCore output Nav2 uses it for
/fusion/odom Set as odom_topic in nav2_params.yaml
odom → base_link TF Costmaps and planners read this directly
/fusion/pose AMCL initial pose, slam_toolbox pose input
/diagnostics Nav2-compatible format

Outdoor GPS navigation (the main path)

One command starts the entire stack: FusionCore + Nav2, lifecycle managed automatically:

ros2 launch fusioncore_ros fusioncore_nav2.launch.py \
  fusioncore_config:=/path/to/your_robot.yaml

The bundled nav2_params.yaml is pre-wired to /fusion/odom and configured for outdoor GPS navigation: NavFn planner with allow_unknown: true, Regulated Pure Pursuit controller, no AMCL, no static map required.

With an environment preset:

ros2 launch fusioncore_ros fusioncore_nav2.launch.py \
  fusioncore_config:=your_robot.yaml \
  env_config:=$(ros2 pkg prefix fusioncore_ros)/share/fusioncore_ros/config/env_urban.yaml

With your own nav2_params.yaml:

ros2 launch fusioncore_ros fusioncore_nav2.launch.py \
  fusioncore_config:=your_robot.yaml \
  nav2_params:=/path/to/your_nav2_params.yaml

GPS waypoint navigation

Once FusionCore has a GPS fix, the fromLL service converts lat/lon to the local map frame for Nav2:

ros2 service call /fromLL fusioncore_ros/srv/FromLL \
  "{ll_point: {latitude: 43.2557, longitude: -79.8711, altitude: 0.0}}"

What the launch file does under the hood

The lifecycle timing is important. fusioncore_nav2.launch.py:

  1. Starts fusioncore_node as a lifecycle node
  2. Waits 2 seconds, sends configure
  3. On configuring → inactive, immediately sends activate
  4. Waits 5 seconds after activation, then starts Nav2

This 5-second delay guarantees odom → base_link TF is publishing before Nav2's costmaps initialize. Without it, Nav2 fails silently at startup.

Updating an existing nav2_params.yaml

If you have your own Nav2 config, find every odom_topic and update it:

# before
bt_navigator:
  ros__parameters:
    odom_topic: /odometry/filtered

velocity_smoother:
  ros__parameters:
    odom_topic: /odometry/filtered

# after
bt_navigator:
  ros__parameters:
    odom_topic: /fusion/odom

velocity_smoother:
  ros__parameters:
    odom_topic: /fusion/odom

Also remove AMCL if you had it. FusionCore publishes the map → odom TF directly via GPS. Running AMCL alongside it will cause TF conflicts.

Indoor navigation (no GPS)

FusionCore works without GPS. Set reference.use_first_fix: false in your config, and the filter starts at the origin on IMU + wheel odometry alone.

For indoor navigation with a map, run slam_toolbox or AMCL alongside FusionCore. FusionCore handles odom → base_link. Your SLAM system handles map → odom.

# FusionCore for odometry
ros2 launch fusioncore_ros fusioncore.launch.py \
  fusioncore_config:=your_robot.yaml

# slam_toolbox for map → odom
ros2 launch slam_toolbox online_async_launch.py

Coming from robot_localization

See the Migration Guide for a complete parameter mapping and step-by-step instructions.