120 lines
6.1 KiB
Markdown
120 lines
6.1 KiB
Markdown
# Architecture Overview
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GPS-denied drone landing simulation with camera vision.
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## System Diagram
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```
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┌─────────────────────────────────────────────────────────────────────────┐
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│ Simulation System │
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├─────────────────────────────────────────────────────────────────────────┤
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│ │
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│ ┌──────────────────┐ ┌──────────────────────────┐ │
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│ │ simulation_host │◄── UDP:5555 ──────►│ ros_bridge.py │ │
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│ │ (PyBullet) │ │ (UDP ↔ ROS Bridge) │ │
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│ └──────────────────┘ └────────────┬─────────────┘ │
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│ OR │ │
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│ ┌──────────────────┐ ┌────────────┴─────────────┐ │
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│ │ Gazebo │◄── ROS Topics ────►│ gazebo_bridge.py │ │
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│ │ (Ignition) │ │ (Gazebo ↔ ROS Bridge) │ │
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│ └──────────────────┘ └────────────┬─────────────┘ │
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│ │ │
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│ ┌────────────▼─────────────┐ │
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│ │ controllers.py │ │
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│ │ ┌─────────────────────┐ │ │
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│ │ │ DroneController │ │ │
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│ │ │ RoverController │ │ │
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│ │ └─────────────────────┘ │ │
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│ └──────────────────────────┘ │
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└─────────────────────────────────────────────────────────────────────────┘
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```
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## Components
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### Simulators
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| Component | Description |
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|-----------|-------------|
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| **PyBullet** (`simulation_host.py`) | Standalone physics, UDP networking, camera rendering |
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| **Gazebo** | Full robotics simulator, native ROS 2 integration, camera sensor |
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### Bridges
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| Component | Description |
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|-----------|-------------|
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| **ros_bridge.py** | Connects PyBullet ↔ ROS 2 via UDP |
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| **gazebo_bridge.py** | Connects Gazebo ↔ ROS 2, provides same interface |
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### Controllers
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| Component | Description |
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|-----------|-------------|
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| **controllers.py** | Runs drone + rover controllers together |
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| **drone_controller.py** | GPS-denied landing logic |
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| **rover_controller.py** | Moving landing pad patterns |
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## ROS Topics
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| Topic | Type | Publisher | Subscriber |
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|-------|------|-----------|------------|
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| `/cmd_vel` | `Twist` | DroneController | Bridge |
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| `/drone/telemetry` | `String` | Bridge | DroneController |
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| `/rover/telemetry` | `String` | RoverController | DroneController |
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| `/rover/cmd_vel` | `Twist` | RoverController | (internal) |
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| `/rover/position` | `Point` | RoverController | (debug) |
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## GPS-Denied Sensor Flow
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```
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Simulator Bridge DroneController
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│ │ │
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│ Render Camera │ │
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│ Compute Physics │ │
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│──────────────────────►│ │
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│ │ │
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│ │ GPS-Denied Sensors: │
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│ │ - IMU │
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│ │ - Altimeter │
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│ │ - Velocity │
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│ │ - Camera Image (JPEG) │
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│ │ - Landing Pad Detection │
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│ │─────────────────────────►│
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│ │ │
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│ │ /cmd_vel │
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│◄──────────────────────│◄─────────────────────────│
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```
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## Camera System
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Both simulators provide a downward-facing camera:
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| Property | Value |
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|----------|-------|
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| Resolution | 320 x 240 |
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| FOV | 60 degrees |
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| Format | Base64 JPEG |
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| Update Rate | ~5 Hz |
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| Direction | Downward |
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## Data Flow
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### PyBullet Mode
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```
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DroneController → /cmd_vel → ros_bridge → UDP:5555 → simulation_host
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simulation_host → UDP:5556 → ros_bridge → /drone/telemetry → DroneController
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```
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### Gazebo Mode
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```
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DroneController → /cmd_vel → gazebo_bridge → /drone/cmd_vel → Gazebo
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Gazebo → /model/drone/odometry → gazebo_bridge → /drone/telemetry → DroneController
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Gazebo → /drone/camera → gazebo_bridge → (encoded in telemetry)
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```
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## UDP Protocol
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| Port | Direction | Content |
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|------|-----------|---------|
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| 5555 | Bridge → Simulator | Command JSON |
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| 5556 | Simulator → Bridge | Telemetry JSON (includes camera image) |
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