160 lines
4.0 KiB
Markdown
160 lines
4.0 KiB
Markdown
# Gazebo Simulation Guide
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Running the GPS-denied drone simulation with Gazebo Ignition Fortress on Linux/WSL2.
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## Quick Start (Two Terminals)
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**Terminal 1 - Launch Gazebo + Bridge:**
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```bash
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source activate.sh
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ros2 launch gazebo/launch/drone_landing.launch.py
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```
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**Terminal 2 - Run Controllers:**
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```bash
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source activate.sh
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python run_gazebo.py --pattern circular --speed 0.3
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```
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Both the drone AND rover will move!
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## Command Options
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```bash
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python run_gazebo.py --help
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Options:
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--pattern stationary, linear, circular, square, random
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--speed, -s Rover speed in m/s (default: 0.5)
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--amplitude, -a Movement amplitude (default: 2.0)
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--no-rover Disable rover controller
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```
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## How It Works
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1. **Gazebo** runs the physics simulation with:
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- Drone with `VelocityControl` plugin (responds to `/drone/cmd_vel`)
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- Rover with `VelocityControl` plugin (responds to `/rover/cmd_vel`)
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2. **ros_gz_bridge** connects Gazebo topics to ROS 2
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3. **run_gazebo.py** starts:
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- `GazeboBridge` - converts ROS topics to telemetry format
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- `DroneController` - your landing algorithm
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- `RoverController` - moves the landing pad
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## GPS-Denied Sensors
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The `GazeboBridge` provides the same sensor interface as PyBullet:
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| Sensor | Source |
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|--------|--------|
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| IMU | Gazebo odometry orientation |
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| Altimeter | Gazebo Z position |
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| Velocity | Gazebo twist |
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| Camera | Gazebo camera sensor (if enabled) |
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| Landing Pad | Computed from relative position |
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## Topics
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### ROS 2 Topics (your code uses these)
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| Topic | Type | Direction |
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|-------|------|-----------|
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| `/cmd_vel` | `Twist` | Input (from DroneController) |
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| `/drone/telemetry` | `String` | Output (to DroneController) |
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| `/rover/telemetry` | `String` | Output (rover position) |
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### Gazebo Topics (bridged automatically)
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| Topic | Type | Description |
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|-------|------|-------------|
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| `/drone/cmd_vel` | `Twist` | Drone velocity commands |
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| `/rover/cmd_vel` | `Twist` | Rover velocity commands |
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| `/model/drone/odometry` | `Odometry` | Drone state |
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| `/drone/imu` | `IMU` | IMU sensor data |
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| `/clock` | `Clock` | Simulation time |
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## Headless Mode (WSL2 / No GPU)
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Run Gazebo without GUI:
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```bash
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# Server mode only
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ign gazebo -s gazebo/worlds/drone_landing.sdf
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```
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Then run the bridge manually:
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```bash
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ros2 run ros_gz_bridge parameter_bridge \
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/drone/cmd_vel@geometry_msgs/msg/Twist]ignition.msgs.Twist \
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/rover/cmd_vel@geometry_msgs/msg/Twist]ignition.msgs.Twist \
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/model/drone/odometry@nav_msgs/msg/Odometry[ignition.msgs.Odometry
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```
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## World File Details
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The world file `gazebo/worlds/drone_landing.sdf` includes:
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- **Drone** at (0, 0, 2) with:
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- `VelocityControl` plugin for movement
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- `OdometryPublisher` plugin for telemetry
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- IMU sensor
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- **Landing Pad (Rover)** at (0, 0, 0.15) with:
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- `VelocityControl` plugin for movement
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- Visual H marker
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## Troubleshooting
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### Drone falls immediately
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The drone should hover with the controller running. If it falls:
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1. Check that `run_gazebo.py` is running
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2. Verify the bridge shows "Passing message from ROS"
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3. Check `/drone/cmd_vel` topic: `ros2 topic echo /drone/cmd_vel`
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### Rover doesn't move
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1. Check that `/rover/cmd_vel` is bridged
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2. Verify RoverController is publishing: `ros2 topic echo /rover/cmd_vel`
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### Model not found
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Set the model path:
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```bash
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export GZ_SIM_RESOURCE_PATH=$PWD/gazebo/models:$GZ_SIM_RESOURCE_PATH
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export IGN_GAZEBO_RESOURCE_PATH=$PWD/gazebo/models:$IGN_GAZEBO_RESOURCE_PATH
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```
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### "Cannot connect to display" (WSL2)
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Use headless mode:
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```bash
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ign gazebo -s gazebo/worlds/drone_landing.sdf
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```
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Or ensure WSLg is working:
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```bash
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export DISPLAY=:0
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```
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### Plugin not found
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For Ignition Fortress, plugins use `libignition-gazebo-*-system.so` naming.
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Check available plugins:
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```bash
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ls /usr/lib/x86_64-linux-gnu/ign-gazebo-6/plugins/
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```
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## Launch File Options
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```bash
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ros2 launch gazebo/launch/drone_landing.launch.py use_sim_time:=true
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```
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| Argument | Default | Description |
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|----------|---------|-------------|
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| `use_sim_time` | `true` | Use Gazebo clock |
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