# Drone Landing Simulation (GPS-Denied)

A GPS-denied drone landing simulation using relative sensors (IMU, altimeter, camera, landing pad detection) with **PyBullet** and **Gazebo** simulators.

## Quick Start

```bash
# Install (Ubuntu)
./setup/install_ubuntu.sh
source activate.sh

# Run PyBullet simulation
python simulation_host.py      # Terminal 1: Simulator
python ros_bridge.py           # Terminal 2: ROS bridge
python controllers.py          # Terminal 3: Drone + Rover controllers

# With moving rover
python controllers.py --pattern circular --speed 0.3
```

## Architecture

```
┌─────────────────────────────────────────────────────────────────────────┐
│  ┌──────────────────┐                    ┌──────────────────────────┐   │
│  │ simulation_host  │◄── UDP:5555 ──────►│    ros_bridge.py         │   │
│  │   (PyBullet)     │                    └────────────┬─────────────┘   │
│  └──────────────────┘                                 │                 │
│          OR                                           │                 │
│  ┌──────────────────┐                    ┌────────────┴─────────────┐   │
│  │     Gazebo       │◄── ROS Topics ────►│    gazebo_bridge.py      │   │
│  └──────────────────┘                    └────────────┬─────────────┘   │
│                                                       │                 │
│                                          ┌────────────▼─────────────┐   │
│                                          │    controllers.py        │   │
│                                          │  ┌─────────────────────┐ │   │
│                                          │  │  DroneController    │ │   │
│                                          │  │  RoverController    │ │   │
│                                          │  └─────────────────────┘ │   │
│                                          └──────────────────────────┘   │
└─────────────────────────────────────────────────────────────────────────┘
```

## Files

| File | Description |
|------|-------------|
| `simulation_host.py` | PyBullet physics simulator |
| `ros_bridge.py` | UDP ↔ ROS 2 bridge |
| `gazebo_bridge.py` | Gazebo ↔ ROS 2 bridge |
| `controllers.py` | **Runs drone + rover together** |
| `drone_controller.py` | Drone landing logic (edit this) |
| `rover_controller.py` | Moving landing pad |

## Controller Options

```bash
python controllers.py --help

Options:
  --pattern, -p   Rover pattern: stationary, linear, circular, random, square
  --speed, -s     Rover speed in m/s (default: 0.5)
  --amplitude, -a Rover amplitude in meters (default: 2.0)
```

## GPS-Denied Sensors

The drone has no GPS. Available sensors:

| Sensor | Data |
|--------|------|
| **IMU** | Orientation, angular velocity |
| **Altimeter** | Altitude, vertical velocity |
| **Velocity** | Estimated horizontal velocity |
| **Camera** | 320x240 downward-facing image (base64 JPEG) |
| **Landing Pad** | Relative position when visible (may be null) |

## Documentation

| Document | Description |
|----------|-------------|
| [Installation](docs/installation.md) | Setup for Ubuntu, macOS, Windows |
| [Architecture](docs/architecture.md) | System components and data flow |
| [Protocol](docs/protocol.md) | Sensor data formats |
| [Drone Guide](docs/drone_guide.md) | How to implement landing logic |
| [Rover Controller](docs/rover_controller.md) | Movement patterns |
| [PyBullet](docs/pybullet.md) | PyBullet-specific setup |
| [Gazebo](docs/gazebo.md) | Gazebo-specific setup |

## Getting Started

1. Read [docs/drone_guide.md](docs/drone_guide.md)
2. Edit `drone_controller.py`
3. Implement `calculate_landing_maneuver()`
4. Run: `python controllers.py --pattern stationary`
5. Increase difficulty: `python controllers.py --pattern circular`