ROS bridge installation
- Bridge installation
- a) using apt repository
- b) using source repository
- Run the ROS bridge
- Setting CARLA
The ROS bridge enables two-way communication between ROS and CARLA. The information from the CARLA server is translated to ROS topics. In the same way, the messages sent between nodes in ROS get translated to commands to be applied in CARLA.
- ROS Kinetic/Melodic. Install ROS Melodic, for Ubuntu 18.04, or Kinetic, for Ubuntu 16.04. ROS packages may be required, depending on the user needs. rviz to visualize ROS data.
- CARLA 0.9.7 or later. Previous versions are not compatible with the ROS bridge. Follow the quick start installation or make the build for the corresponding platform.
Make sure that both CARLA and ROS work properly before continuing with the installation.
a) Using apt repository
Add the apt repository.
- Bridge for ROS Melodic.
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 81061A1A042F527D && sudo add-apt-repository "deb [arch=amd64 trusted=yes] http://dist.carla.org/carla-ros-bridge-melodic/ bionic main"
- Bridge for ROS Kinetic.
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 9BE2A0CDC0161D6C && sudo add-apt-repository "deb [arch=amd64 trusted=yes] http://dist.carla.org/carla-ros-bridge-kinetic xenial main"
Install the ROS bridge.
sudo apt update && sudo apt install carla-ros-bridge-<melodic or kinetic>
b) Using source repository
A catkin workspace is needed to use the ROS bridge. It should be cloned and built in there. The following code creates a new workspace, and clones the repository in there.
#setup folder structure mkdir -p ~/carla-ros-bridge/catkin_ws/src cd ~/carla-ros-bridge git clone https://github.com/carla-simulator/ros-bridge.git cd ros-bridge git submodule update --init cd ../catkin_ws/src ln -s ../../ros-bridge source /opt/ros/kinetic/setup.bash #Watch out, this sets ROS Kinetic. cd .. #install required ros-dependencies rosdep update rosdep install --from-paths src --ignore-src -r #build catkin_make
Run the ROS bridge
1) Run CARLA. The way to do so depends on the CARLA installation.
- Quick start/release package.
- apt installation.
- Build installation.
2) Add the source path. The source path for the workspace has to be added, so that the ROS bridge can be used from a terminal.
- Source for apt ROS bridge.
source /opt/carla-ros-bridge/<melodic or kinetic>/setup.bash
- Source for ROS bridge repository download.
The source path can be set permanently, but it will cause conflict when working with another workspace.
3) Start the ROS bridge. Use any of the different launch files available to check the installation. Here are some suggestions.
# Option 1: start the ros bridge roslaunch carla_ros_bridge carla_ros_bridge.launch # Option 2: start the ros bridge together with RVIZ roslaunch carla_ros_bridge carla_ros_bridge_with_rviz.launch # Option 3: start the ros bridge together with an example ego vehicle roslaunch carla_ros_bridge carla_ros_bridge_with_example_ego_vehicle.launch
The path to CARLA Python is missing. The apt installation does this automatically, but it may be missing for other installations. Execute the following command with the complete path to the .egg file (included). Use the one supported by the Python version installed.
ImportError: no module named CARLA
Note: .egg files may be either in `/PythonAPI/` or `/PythonAPI/dist/` depending on the CARLA installation.
Import CARLA from Python and wait for a sucess message to check the installation.
python -c 'import carla;print("Success")'
To modify the way CARLA works along with the ROS bridge, edit
- Host/port. Network settings to connect to CARLA using a Python client.
- Synchronous mode.
- If false (default). Data is published on every
- If true The bridge waits for all the sensor messages expected before the next tick. This might slow down the overall simulation but ensures reproducible results.
- If false (default). Data is published on every
- Wait for vehicle command. In synchronous mode, pauses the tick until a vehicle control is completed.
- Simulation time-step. Simulation time (delta seconds) between simulation steps. It must be lower than 0.1. Take a look at the documentation to learn more about this.
- Role names for the Ego vehicles. Role names to identify ego vehicles. These will be controllable from ROS and thus, relevant topics will be created.
In synchronous mode only the ros-bridge is allowed to tick. Other clients must passively wait.
To control the step update when in synchronous mode, use the following topic. The message contains a constant named
command that allows to Pause/Play the simulation, and execute a single step.
The Control rqt plugin launches a new window with a simple interface. It is used to manage the steps and publish in the corresponding topic. Simply run the following when CARLA in synchronous mode.
rqt --standalone rqt_carla_control