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This Markdown file contains different architecture diagrams for the project, and it should replace some outdated documentation by the previous team (CatScanner 2024-2025).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

Guide

    flowchart TD
    %%Style
        classDef A fill:green,stroke:black
        classDef D fill:grey,stroke:black

    subgraph Node_in_ROS2
        running_file_is_green.cpp:::A
        not_running_file_is_grey.py:::D
    end
    Node_in_ROS2 --publish--> topic --subscribe-->Node_in_ROS2

Green: Files that are included in CMakeList.txt.

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

Diagram

    flowchart TD

    %%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

        subgraph px4_handler
            drone_movement_node
            offboard_control
        end
    
    %%Vision package
        
        subgraph image_publisher
            image_publisher.cpp:::A
            arducam_publisher.py:::A
            video_publisher.py:::A
        end

        subgraph image_subscriber
            image_subscriber.cpp:::A
        end

        subgraph object_detection_node
            ball_detector.py:::D
            object_detector.py:::A
        end

        subgraph object_tracker_node
            object_tracker.py:::A
        end

        subgraph video_recorder
            record_video_from_rosbag.py:::D
        end

        subgraph tracked_image_publisher
            track_publisher.py:::A
        end

    %%ball_finder.py

        drone_movement_node -->/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 --> /fmu/in/offboard_control_mode

        offboard_control --> /fmu/in/trajectory_setpoint

        offboard_control --> /fmu/in/vehicle_command

        /custom_trajectory--> offboard_control

        /fmu/out/vehicle_local_position -->offboard_control

    %%image_publisher

        image_publisher --> /image_topic

    %%image_subscriber

        /image_topic --> image_subscriber

    %%object_detection_node

        /image_topic --> object_detection_node
        
        object_detection_node --> /detected_objects_topic

       object_detector.py --> /image_dimension_topic

       object_detector.py --> /detections

    %%object_tracker_node

        /detected_objects_topic --> object_tracker_node

        object_tracker_node --> /tracked_objects_topic

    %%video_recorder
        /image_topic --> video_recorder 

    %%tracked_image_publisher

        /image_topic --> tracked_image_publisher

        /tracked_objects_topic --> tracked_image_publisher

        tracked_image_publisher --> /tracked_image_topic

    %%Other components

        gazebo?((simulation_image_bridge)) --/camera--> object_detector.py

        camera((Camera)) --/dev/video0 --> image_publisher.cpp

        camera((Camera)) --/dev/video0 --> arducam_publisher.py

        web((Web)) --> video_publisher.py