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Changelog

All notable changes to the Smart Drone System project.

[0.1.0] - 2026-08-21

What Was Built

A multi-node drone simulation system on Fedora 44 with ROS 2 Lyrical demonstrating:

  • 5 Python nodes communicating over topics, services, and actions
  • Custom message/service/action definitions (drone_interfaces package)
  • Simulated sensor data, state machine, waypoint navigation, CLI command tool
  • Full integration verified: sensors -> state machine -> controller -> ground station

Architecture

sensor_node ──/drone/sensors──► state_machine_node
                                  ──/drone/state──► ground_station_node
command_node ──takeoff/land──► state_machine_node
             ──goto──────────► controller_node ──/drone/cmd_waypoint──► (action)

Key Decisions

  • All Python: C++ compilation failed due to missing transitive include directories in Lyrical COPR packages (type_description_interfaces, etc.). Converted state_machine_node from C++ to Python to unblock progress.
  • ament_python for drone_system: Used setup.py with entry_points instead of CMake. drone_interfaces remains ament_cmake (CMake is required for rosidl code generation).
  • Wrapper scripts: Created shell wrappers in install/<pkg>/lib/<pkg>/ to make ros2 run work (see Core Issues below).

Core Issues & Solutions

1. ament_target_dependencies does not exist in Lyrical

The ament_cmake package in this Lyrical build removed ament_target_dependencies(). Any CMakeLists.txt using it fails at configure time.

Solution: Use target_link_libraries() or avoid C++ entirely. All drone_system nodes are Python.

2. C++ compilation fails - missing transitive includes

COPR packages don't export transitive include paths for interfaces like type_description_interfaces, unique_identifier_msgs, etc. This means any C++ node that depends on custom messages won't compile.

Solution: Rewrote state_machine_node in Python. No C++ code remains in drone_system.

3. ros2 run drone_system <node> - "No executable found"

The ament_python package is not available in the Lyrical COPR. Without it, colcon build for ament_python packages does not create the lib/<package_name>/ directory that ros2 run searches for executables.

Solution: Created build.sh which generates shell wrapper scripts:

#!/bin/bash
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
exec python3 "$SCRIPT_DIR/../python3.14/site-packages/drone_system/<node>.py" "$@"

These wrappers are placed in install/drone_system/lib/drone_system/ where ros2 run expects them.

Limitation: Wrappers are lost on each colcon build. Must run build.sh or manually recreate them after building.

4. ros2 launch not available

The ros2 launch extension is not included in the Lyrical ros2cli package. Running ros2 launch gives:

error: argument Call `ros2 <command> -h` for more detailed usage.:
invalid choice: 'launch'

Solution: Run nodes individually in separate terminals. Launch files are included for reference and future use when the extension becomes available.

5. self.get_logger().warn() API change

In Lyrical, RcutilsLogger.warn() was removed. Must use self.get_logger().warning() instead.

Solution: Replaced all .warn( calls with .warning( in state_machine_node.py.

File Structure

src/
├── drone_interfaces/          # Custom .msg, .srv, .action (ament_cmake)
│   ├── msg/SensorData.msg
│   ├── msg/DroneState.msg
│   ├── srv/Takeoff.srv
│   ├── srv/Land.srv
│   ├── srv/EmergencyStop.srv
│   └── action/GoToWaypoint.action
└── drone_system/              # All nodes (ament_python)
    ├── drone_system/
    │   ├── sensor_node.py
    │   ├── state_machine_node.py
    │   ├── controller_node.py
    │   ├── ground_station_node.py
    │   └── command_node.py
    ├── launch/                # Launch files (for future use)
    ├── config/params.yaml
    ├── setup.py
    └── package.xml

Build & Run

# Build
source /opt/ros/lyrical/setup.bash
colcon build --packages-select drone_interfaces
source install/setup.bash
colcon build --packages-select drone_system
source install/setup.bash

# Create ros2 run wrappers (required after each build)
./build.sh

# Run nodes
ros2 run drone_system sensor_node
ros2 run drone_system state_machine_node
ros2 run drone_system controller_node
ros2 run drone_system ground_station_node
ros2 run drone_system command_node takeoff 10.0

Dependencies

sudo dnf install ros-lyrical-ros-desktop
sudo dnf install ros-lyrical-rosidl-default-generators ros-lyrical-rosidl-default-runtime