Indoor / GPS-denied robots (LiDAR ICP odometry)¶

For robots operating indoors, underground, or anywhere GPS isn't available. FusionCore runs fine without GPS: it starts at the origin and builds a local odometry frame from IMU + LiDAR ICP alone.

Common setups this covers¶

Indoor mobile robots (warehouses, offices, labs)
Robots with a LiDAR running KISS-ICP or rtabmap icp_odometry
Robots where wheel odometry is unreliable or unavailable
OAK-D camera + Velodyne/RPLiDAR + any ground robot

Quick start¶

ros2 launch fusioncore_ros fusioncore.launch.py \
  fusioncore_config:=$(ros2 pkg prefix fusioncore_ros)/share/fusioncore_ros/config/icp_indoor.yaml \
  --ros-args \
  -r /odom/wheels:=/kiss/odometry

Replace /kiss/odometry with whatever your ICP pipeline publishes:

ICP pipeline	Default topic
KISS-ICP	`/kiss/odometry`
rtabmap `icp_odometry`	`/icp_odom`
cartographer	`/tracked_pose` (pose only: needs twist wrapper)

FusionCore treats LiDAR ICP odometry exactly like wheel odometry: same outlier gate, same adaptive noise, same ZUPT logic. The only difference is the noise values: ICP is more accurate than wheels so icp_indoor.yaml uses tighter defaults (encoder.vel_noise: 0.02 instead of 0.05).

If you also have wheel odometry¶

If your wheel odom is reliable, use it as primary and add ICP as a second cross-check via encoder2.topic:

# in icp_indoor.yaml
encoder2.topic: "/kiss/odometry"

Then launch without the remap: FusionCore subscribes to /odom/wheels natively and picks up ICP as a second velocity source.

SLAM integration (slam_toolbox, RTABMAP)¶

FusionCore and your SLAM system divide the TF tree cleanly:

map → odom        ← your SLAM system (slam_toolbox, RTABMAP)
odom → base_link  ← FusionCore

They don't conflict. Just launch both:

# Terminal 1: FusionCore
ros2 launch fusioncore_ros fusioncore.launch.py \
  fusioncore_config:=icp_indoor.yaml \
  --ros-args -r /odom/wheels:=/kiss/odometry

# Terminal 2: slam_toolbox
ros2 launch slam_toolbox online_async_launch.py

# or RTABMAP
ros2 launch rtabmap_slam rtabmap.launch.py

Nav2 reads from /fusion/odom as usual.

IMU topic remaps¶

Most drivers publish at /imu/data already and need no remap. Exceptions:

Driver	Topic	Remap needed
OAK-D (depthai-ros)	`/imu`	`-r /imu/data:=/imu`
Realsense D435i	`/camera/imu`	`-r /imu/data:=/camera/imu`
Most others	`/imu/data`	none

Also set imu.frame_id in your config if your driver doesn't fill in header.frame_id:

imu.frame_id: "oak_imu_frame"      # OAK-D
imu.frame_id: "camera_imu_optical_frame"  # Realsense

One thing to get right: startup bias init¶

Without GPS corrections, IMU bias matters more indoors. Add this to your config:

init.stationary_window: 2.0

This collects 2 seconds of stationary IMU data at startup to estimate bias before the filter starts. Reduces startup drift from ~10 cm to under 1 cm. Robot must be stationary for the first 2 seconds after launch: it falls back automatically if it detects movement.

The icp_indoor.yaml config has this enabled by default.