# ArduPilot GPS-Denied Simulation

Realistic flight controller simulation with your drone logic.

## Quick Start (2 Terminals)

**Terminal 1 - Gazebo:**
```bash
./scripts/run_ardupilot_sim.sh runway
# Options: runway, warehouse, zephyr
```

**Terminal 2 - Controller + SITL:**
```bash
./scripts/run_ardupilot_controller.sh
```

## How It Works

The `run_ardupilot_controller.sh` script starts ArduPilot SITL in the background and connects your controller to it via MAVLink.

```
┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│ Gazebo          │◄───►│ ArduPilot SITL  │◄───►│ run_ardupilot.py│
│ (Physics)       │JSON │ (Hidden)        │MAV  │ (Your Logic)    │
└─────────────────┘     └─────────────────┘     └─────────────────┘
                                                        │
                                                        ▼
                                               drone_controller.py
```

## Manual Mode (Debugging)

If you need to debug with MAVProxy console (3 Terminals):

**Terminal 1:**
```bash
./scripts/run_ardupilot_sim.sh runway
```

**Terminal 2:**
```bash
sim_vehicle.py -v ArduCopter -f gazebo-iris --model JSON --console
```

**Terminal 3:**
```bash
# Debug commands in MAVProxy:
param set ARMING_CHECK 0
mode guided
arm throttle force
```

## Installation

```bash
./setup/install_ardupilot.sh
source ~/.bashrc
```

## Configuration

Your `drone_controller.py` receives telemetry and returns control inputs.

The simulation translates your inputs:
- `thrust` → Vertical velocity
- `pitch/roll` → Horizontal velocity
- `yaw` → Yaw rate

## Troubleshooting

### "SITL failed to start"
Check if `sim_vehicle.py` is in your PATH:
```bash
export PATH=$PATH:~/ardupilot/Tools/autotest
```

### Drone drift
ArduPilot in GUIDED mode requires good position estimation. Without GPS, it relies on optical flow or visual odometry (not yet implemented in default setup). The drone might drift if relying only on IMU.

### "No JSON sensor message"
Ensure Gazebo (Terminal 1) is running before starting the controller.

## Visualizing Camera

```bash
python camera_viewer.py --topic /drone/camera
```
(Requires bridging the topic if using ROS 2 bridge)