RDC_Simulation/docs/architecture.md

Architecture Overview

Modes

1. Standalone (1 Terminal)

python standalone_simulation.py --pattern circular

┌────────────────────────────────────────┐
│      standalone_simulation.py          │
│  PyBullet + Controllers + Camera       │
└────────────────────────────────────────┘

2. Gazebo + ROS 2 (2 Terminals)

Terminal 1                    Terminal 2
┌───────────────────┐        ┌───────────────────┐
│ Gazebo + Bridge   │◄──────►│ run_gazebo.py     │
└───────────────────┘  ROS   └───────────────────┘

3. ArduPilot (2 Terminals)

Terminal 1                    Terminal 2
┌───────────────────┐        ┌────────────────────────────┐
│ Gazebo +          │◄──────►│ run_ardupilot_controller.sh│
│ ArduPilot Plugin  │  JSON  │ ┌──────────────────┐       │
└───────────────────┘        │ │ ArduPilot SITL   │       │
                             │ └─────────┬────────┘       │
                             │           │ MAVLink        │
                             │ ┌─────────▼────────┐       │
                             │ │ run_ardupilot.py │       │
                             │ └──────────────────┘       │
                             └────────────────────────────┘

Data Flow

Standalone

Controller → PyBullet → Telemetry → Controller

Gazebo

Controller → /cmd_vel → Gazebo → /odometry → Controller

ArduPilot

Gazebo ◄─── JSON ───► SITL ◄─── MAVLink ───► Controller

Key Files

File	Purpose
drone_controller.py	Your landing algorithm (used in ALL modes)
run_ardupilot.py	MAVLink interface for ArduPilot
run_gazebo.py	ROS 2 interface for Gazebo
standalone_simulation.py	PyBullet simulation engine
config.py	Shared configuration

GPS-Denied Sensors

The controller receives this standardized telemetry structure in all modes:

telemetry = {
    "altimeter": {
        "altitude": float,           # Meters
        "vertical_velocity": float   # m/s (positive = up)
    },
    "velocity": {                    # Body or Local frame
        "x": float,
        "y": float,
        "z": float
    },
    "imu": {
        "orientation": {
            "roll": float,
            "pitch": float,
            "yaw": float
        }
    },
    "landing_pad": {                 # If visible (None otherwise)
        "relative_x": float,
        "relative_y": float,
        "distance": float
    }
}