Software architecture diagram

This Markdown file contains different architecture diagrams for the project, and it should replace some outdated documentation by the previous team (CatScanner 2024-2025). Currently, we use Markdown Preview Mermaid Support by Matt Bierner to simplify the creation process. After installing the extension, the diagram will be shown in the preview.

If you cannot install the extension for some reason, you can download another Mermaid-compatible extension and modify the code manually to match the format.

If you are new to Mermaid and want to get familiar with it, please check the Youtube video by PetterTech, Youtube video by Red Gregory, or The official documentation by mermaid.js.org.

Changelog

Date	Changes
2026-01-09	Add ROS2 node architecture diagram

1. Relationship between different ROS2 nodes

Green: Files that are included in CMakeList.txt.

Gray: Files that are not compiled in CMakeList.txt (legacy code, testing, debug, etc).

Diagram

    flowchart TB
    %%Style for color
        %% Activated
        classDef A fill:green,stroke:black

        %% Deactivated
        classDef D fill:grey,stroke:black

    %%PX4_handler
        subgraph drone_movement_node
            ball_finder.py:::A
        end

        subgraph offboard_control
            offboard_control.cpp:::A
        end

    %%Vision package

        subgraph argus-kitten
            isaac_ros_argus_camera_mono:::A
        end

        subgraph object_detection_node
            object_detector.py:::A
        end

    %%ball_finder.py

        drone_movement_node --movement commands -->/custom_trajectory

        drone_movement_node -->/fmu/in/vehicle_command

        /fmu/out/vehicle_local_position --> drone_movement_node

        /detections --> drone_movement_node

    %%offboard_control.cpp

        offboard_control --enable offboard mode --> /fmu/in/offboard_control_mode

        offboard_control --movement commands --> /fmu/in/trajectory_setpoint

        /custom_trajectory--> offboard_control

        /fmu/out/vehicle_local_position -->offboard_control

    %%argus-kitten

        argus-kitten --video feed --> /argus/left/image_raw

    %%object_detection_node

        /argus/left/image_raw --> object_detection_node

       object_detector.py --detected objects --> /detections

    %% Point odometry
        subgraph point_odometry
            point_odometry.cpp:::A
        end

        /detections --> point_odometry
        /fmu/out/vehicle_odometry --> point_odometry
        point_odometry --> /fmu/in/vehicle_visual_odometry

    %%Stereo camera
        subgraph stereo_node
            stereo_publisher.cpp:::A
        end

        subgraph stereo_topics["Stereo Topics"]
            topics["
                /left/image_rect
                /left/camera_info
                /right/image_rect
                /right/camera_info
                /imu
                /tf_static
            "]
        end
        stereo_publisher.cpp --camera feed --> stereo_topics

    %%VSLAM
        subgraph visual_slam_node
            isaac_ros_visual_slam:::A
        end
        stereo_topics --> isaac_ros_visual_slam
        isaac_ros_visual_slam --pose estimates --> /visual_slam/tracking/odometry
        /visual_slam/tracking/odometry --vslam_message_transform.cpp --> /fmu/in/vehicle_visual_odometry
        /fmu/in/vehicle_visual_odometry --> ekf2

    %%Cameras
        camera((Downward Camera)) --/dev/video0 --> isaac_ros_argus_camera_mono

        stereo_camera((OAK-D Pro Stereo Camera)) --/dev/bus/usb --> stereo_publisher.cpp

    %% Flight control / PX4
        subgraph flight_controller_inputs["Flight Controller Inputs"]
            IMU
            Barometer
            Magnetometer
        end
        px4(("Flight Controller (PX4)")) --measured data --> flight_controller_inputs
        flight_controller_inputs --> ekf2[EKF2]:::A
        ekf2 --position estimates --> /fmu/out/vehicle_local_position
        /fmu/in/offboard_control_mode --> px4
        /fmu/in/trajectory_setpoint --> px4
        /fmu/in/vehicle_command --> px4