# Architecture Overview

## Operation Modes

### 1. Standalone (Any Platform)

Single process, no ROS 2 required:

```bash
python standalone_simulation.py --pattern circular
```

```
┌────────────────────────────────────────┐
│      standalone_simulation.py          │
│  ┌──────────────────────────────────┐  │
│  │  PyBullet Physics + Camera       │  │
│  │  Built-in Controller             │  │
│  │  Rover Movement                  │  │
│  └──────────────────────────────────┘  │
└────────────────────────────────────────┘
```

### 2. Gazebo + ROS 2 (2 Terminals)

**Terminal 1:**
```bash
ros2 launch gazebo/launch/drone_landing.launch.py
```

**Terminal 2:**
```bash
python run_gazebo.py --pattern circular
```

```
Terminal 1                    Terminal 2
┌───────────────────┐        ┌───────────────────┐
│ Gazebo + Bridge   │◄──────►│ run_gazebo.py     │
│ (Physics)         │  ROS   │ + Controllers     │
└───────────────────┘        └───────────────────┘
```

### 3. ArduPilot SITL (2 Terminals)

**Terminal 1:**
```bash
ros2 launch ardupilot_gz_bringup iris_runway.launch.py
```

**Terminal 2:**
```bash
mavproxy.py --console --map --master=:14550
```

```
┌─────────────────────────────────────────────┐
│        Single Launch Command                │
│   (Starts SITL + Gazebo + RViz)            │
├─────────────────────────────────────────────┤
│  ArduPilot SITL ◄──► Gazebo ◄──► ROS 2     │
│       ▲                                     │
│       │ /ap/* topics                        │
│       ▼                                     │
│  MAVProxy (GCS)                            │
└─────────────────────────────────────────────┘
```

## Key Components

| Component | Description |
|-----------|-------------|
| `drone_controller.py` | Your landing algorithm |
| `gazebo_bridge.py` | Gazebo ↔ ROS bridge |
| `mavlink_bridge.py` | MAVLink commands |
| `camera_viewer.py` | Camera display |

## ROS 2 Topics

| Topic | Direction | Description |
|-------|-----------|-------------|
| `/drone/telemetry` | ← | Sensor data (JSON) |
| `/cmd_vel` | → | Velocity commands |
| `/drone/camera` | ← | Camera images |
| `/rover/telemetry` | ← | Landing pad position |

## ArduPilot Topics

| Topic | Type |
|-------|------|
| `/ap/pose/filtered` | Position |
| `/ap/twist/filtered` | Velocity |
| `/ap/imu/filtered` | IMU |
| `/ap/battery` | Battery |