Orca4

Orca4 is a set of ROS2 packages that provide basic AUV (Autonomous Underwater Vehicle) functionality for the BlueRobotics BlueROV2.

Orca4 uses ArduSub as the flight controller and mavros as the GCS.

Orca4 runs in Gazebo Harmonic using the standard buoyancy, hydrodynamics and thruster plugins. The connection between ArduSub and Gazebo is provided by ardupilot_gazebo.

Sensors

The BlueROV2 provides the following interesting sensors: * An external barometer provides depth * An IMU provides attitude

Orca4 adds a simulated down-facing stereo camera and ORB_SLAM2 to generate a 3D pose as long as the camera has a good view of the seafloor. The pose is sent to ArduSub and fused with the other sensor information.

If there is no view of the seafloor a synthetic pose is generated based on the last good pose and a simple motion model.

See orca_base for details.

Navigation

Orca4 uses the Navigation2 framework for mission planning and navigation. Several simple Nav2 plugins are provided to work in a 3D environment: * straightlineplanner3d * purepursuit3d * progresschecker3d * goalchecker_3d

See orca_nav2 for details.

Installation

See the Dockerfile for installation details.

Install these packages: * ROS2 Humble * Gazebo Harmonic * ros_gz for Humble + Harmonic (ros-humble-gzharmonic) * ArduSub

Build ArduSub for SITL: ~~~ cd ~/ardupilot ./waf configure --board sitl ./waf sub ~~~

Populate the workspace: ~~~ mkdir -p ~/colconws/src cd colconws/src git clone https://github.com/clydemcqueen/orca4 vcs import < orca4/workspace.repos ~~~

Get dependencies: ~~~ rosdep update rosdep install -y --from-paths . --ignore-src ~~~

MAVROS depends on GeographicLib, and GeographicLib needs some datasets: ~~~ wget https://raw.githubusercontent.com/mavlink/mavros/master/mavros/scripts/installgeographiclibdatasets.sh chmod a+x installgeographiclibdatasets.sh sudo ./installgeographiclibdatasets.sh ~~~

Build the workspace: ~~~ cd ~/colcon_ws colcon build ~~~

Simulation

In a terminal run: ~~~ source src/orca4/setup.bash ros2 launch orcabringup simlaunch.py ~~~

This will bring up all of the components, including the Gazebo UI. The surface of the water is at Z=0 and the sub will be sitting at the surface. The world contains a sandy seafloor 10 meters below the surface.

You should see ArduSub establish a connection to the ardupilotgazebo plugin: ~~~ [ardusub-2] JSON received: [ardusub-2] timestamp [ardusub-2] imu: gyro [ardusub-2] imu: accelbody [ardusub-2] position [ardusub-2] quaternion [ardusub-2] velocity ~~~

At this point SLAM is not running because the seafloor is too far away, but the sub can still move using dead-reckoning. The base_controller node will send default camera poses to ArduSub to warm up the EKF and the manager node will request attitude information at 20Hz. Initialization completes when there is a good pose from the EKF:

~~~ [mavrosnode-8] [INFO] [mavros.imu/handleattitudequaternion]: IMU: Attitude quaternion IMU detected! [manager-9] [INFO] [manager/operator()]: EKF is running [base_controller-10] [INFO] [basecontroller/changestate]: EKF is running, state => RUNNOMAP [base_controller-10] [INFO] [basecontroller/UnderwaterMotion]: initialize odometry to {{-2.52304e-05, -3.28182e-05, -0.228547}, {0, 0, -5.00936e-05}} ~~~

Execute a mission in a second terminal: ~~~ source src/orca4/setup.bash ros2 run orcabringup missionrunner.py ~~~

The default mission will dive to -7m and move in a large rectangle. At -6m the cameras will pick up a view of the seafloor at and ORBSLAM2 will start: ~~~ [orbslam2rosstereo-13] New map created with 571 points [basecontroller-10] [INFO] [basecontroller/changestate]: map created, state => RUNLOCALIZED ~~~

You should notice a loop closure sometime during the 2nd run around the rectangle. The adjustment is very small.

~~~ [orbslam2rosstereo-13] Loop detected! [orbslam2rosstereo-13] Local Mapping STOP [orbslam2rosstereo-13] Local Mapping RELEASE [orbslam2rosstereo-13] Starting Global Bundle Adjustment [orbslam2rosstereo-13] Global Bundle Adjustment finished [orbslam2rosstereo-13] Updating map ... [orbslam2rosstereo-13] Local Mapping STOP [orbslam2rosstereo-13] Local Mapping RELEASE [orbslam2ros_stereo-13] Map updated! ~~~

Packages

• orca_base Base controller, localization, frames
• orca_bringup Launch files
• orca_description SDF files
• orca_msgs Custom messages
• orca_nav2 Nav2 plugins
• orca_shared Dynamics model, shared utilities