RKO-LIO

Robust LiDAR-Inertial Odometry Without Sensor-Specific Modelling

Four different platforms, four different environments, one odometry system

Quick Start

Following is for the python version, see ROS for that.

Assuming you have a rosbag (ros1/ros2) which contains a TF tree, you can run RKO-LIO through

pip install "rko_lio[all]"
# or
pip install rko_lio rosbags "rerun-sdk>=0.31"
# data path should be a directory with *.bag files (ROS1) or a metadata.yaml (ROS2)
rko_lio -v /path/to/data

Why pip install those three packages?

• rko_lio -> the odometry package
• rosbags -> required for the rosbag dataloader. Both ros1 and ros2 bags are supported!
• rerun-sdk -> required for the optional visualizer (-v flag)

pip install "rko_lio[all]" fetches the other optional dependencies as well.

Check further options for the CLI through rko_lio --help.

To dump a default config you can edit and pass with --config, run rko_lio --dump_config.

More details are available in the Python docs.

Extrinsics and convention

Please note that the system needs the extrinsic to be specified between IMU and LiDAR. Either your data includes this in some format, and then the dataloaders try to automatically read it, or otherwise you can specify it in a config file (required if it’s missing in the data). Pass the config file with

rko_lio --config config_file.yaml

This file needs two keys: extrinsic_imu2base_quat_xyzw_xyz and extrinsic_lidar2base_quat_xyzw_xyz, which must each be a list. For example: [0,0,0,1,0,0,0] for identity. Both keys are required.

Throughout this package, I refer to transformations using transform_<from-frame>2<to-frame>. By this, I mean a transformation that converts a vector expressed in the <from-frame> coordinate system to the <to-frame> coordinate system. Mathematically, this translates to:

The superscript on the vector indicates the frame in which the vector is expressed, and $^{ \mathrm{to} }\mathbf{T}_{\mathrm{from}}$ corresponds to transform_<from-frame>_to_<to-frame>.

ROS

Supported distros: Humble, Jazzy, Kilted, Rolling.

sudo apt install ros-$ROS_DISTRO-rko-lio

Or if you’d like to build from source, clone the repo into your colcon workspace and

rosdep install --from-paths src --ignore-src -r -y
colcon build --packages-select rko_lio  # --symlink-install --event-handlers console_direct+

In case you cannot system install the necessary dependencies through rosdep, you can also build the dependencies while building RKO-LIO

colcon build --packages-select rko_lio --cmake-args -DRKO_LIO_FETCH_CONTENT_DEPS=ON

A launch file is provided:

ros2 launch rko_lio odometry.launch.py imu_topic:=<topic> lidar_topic:=<topic> base_frame:=base_link

The three parameters imu_topic, lidar_topic, and base_frame are the minimum you need to specify for the launch file. You can specify them and other options all at once in a config file passed with config_file:=file.yaml.

Check further launch configuration options through ros2 launch rko_lio odometry.launch.py -s

More details are available in the ROS docs.

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