ROS bridge for CARLA simulator

This ROS package aims at providing a simple ROS bridge for CARLA simulator.

Important Note: This documentation is for CARLA versions newer than 0.9.4.

Features

• Cameras (depth, segmentation, rgb) support
• Transform publications
• Manual control using ackermann msg
• Handle ROS dependencies
• Marker/bounding box messages for cars/pedestrian
• Lidar sensor support
• Rosbag in the bridge (in order to avoid rosbag record -a small time errors)
• Add traffic light support

Setup

Create a catkin workspace and install carla_ros_bridge package

#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 catkin_ws/src
ln -s ../../ros-bridge
source /opt/ros/kinetic/setup.bash
cd ..

#install required ros-dependencies
rosdep update
rosdep install --from-paths src --ignore-src -r

#build
catkin_make

For more information about configuring a ROS environment see http://wiki.ros.org/ROS/Tutorials/InstallingandConfiguringROSEnvironment

Start the ROS bridge

First run the simulator (see carla documentation: http://carla.readthedocs.io/en/latest/)

./CarlaUE4.sh -windowed -ResX=320 -ResY=240 -benchmark -fps=10

Wait for the message:

Waiting for the client to connect...

Then start the ros bridge (choose one option):

export PYTHONPATH=$PYTHONPATH:<path/to/carla/>/PythonAPI/<your_egg_file>
source ~/carla-ros-bridge/catkin_ws/devel/setup.bash

# 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

You can setup the ros bridge configuration carla_ros_bridge/config/settings.yaml.

As we have not spawned any vehicle and have not added any sensors in our carla world there would not be any stream of data yet.

You can make use of the CARLA Python API script manual_control.py.

cd <path/to/carla/>
python manual_control.py --rolename=ego_vehicle

This spawns a carla client with role_name='ego_vehicle'. If the rolename is within the list specified by ROS parameter /carla/ego_vehicle/rolename, the client is interpreted as an controllable ego vehicle and all relevant ROS topics are created.

To simulate traffic, you can spawn automatically moving vehicles by using spawn_npc.py from CARLA Python API.

Available ROS Topics

Ego Vehicle

Odometry

Topic	Type
/carla/<ROLE NAME>/odometry	nav_msgs.Odometry

Sensors

The ego vehicle sensors are provided via topics with prefix /carla/ego_vehicle/<sensor_topic>

Currently the following sensors are supported:

Camera

Topic	Type
/carla/<ROLE NAME>/camera/rgb/<SENSOR ROLE NAME>/image_color	sensor_msgs.Image
/carla/<ROLE NAME>/camera/rgb/<SENSOR ROLE NAME>/camera_info	sensor_msgs.CameraInfo

Lidar

Topic	Type
/carla/<ROLE NAME>/lidar/<SENSOR ROLE NAME>/point_cloud	sensor_msgs.PointCloud2

GNSS

Topic	Type
/carla/<ROLE NAME>/gnss/front/gnss	sensor_msgs.NavSatFix

Collision Sensor

Topic	Type
/carla/<ROLE NAME>/collision	carla_ros_bridge_msgs.CarlaCollisionEvent

Lane Invasion Sensor

Topic	Type
/carla/<ROLE NAME>/lane_invasion	carla_ros_bridge_msgs.CarlaLaneInvasionEvent

Control

Topic	Type
/carla/<ROLE NAME>/vehicle_control_cmd (subscriber)	carla_ros_bridge_msgs.CarlaEgoVehicleControl
/carla/<ROLE NAME>/vehicle_status	carla_ros_bridge_msgs.CarlaEgoVehicleStatus
/carla/<ROLE NAME>/vehicle_info	carla_ros_bridge_msgs.CarlaEgoVehicleInfo

You can stear the ego vehicle from the commandline by publishing to the topic /carla/<ROLE NAME>/vehicle_control_cmd.

Examples for a ego vehicle with role_name 'ego_vehicle':

Max forward throttle:

 rostopic pub /carla/ego_vehicle/vehicle_control_cmd carla_ros_bridge/CarlaEgoVehicleControl "{throttle: 1.0, steer: 0.0}" -r 10

Max forward throttle with max steering to the right:

 rostopic pub /carla/ego_vehicle/vehicle_control_cmd carla_ros_bridge/CarlaEgoVehicleControl "{throttle: 1.0, steer: 1.0}" -r 10

The current status of the vehicle can be received via topic /carla/<ROLE NAME>/vehicle_status. Static information about the vehicle can be received via /carla/<ROLE NAME>/vehicle_info

Carla Ackermann Control

In certain cases, the Carla Control Command is not ideal to connect to an AD stack. Therefore a ROS-based node carla_ackermann_control is provided which reads AckermannDrive messages. You can find further documentation here.

Other Topics

Object information of other vehicles

Topic	Type
/carla/objects	derived_object_msgs.String

Object information of all vehicles, except the ego-vehicle(s) is published.

Map

Topic	Type
/carla/map	std_msgs.String

The OPEN Drive map description is published.

Example Ego Vehicle

An example Carla Client to spawn and control an ego vehicle is available. You can find further documentation here.

Waypoint calculation

To make use of the Carla waypoint calculation a ROS Node is available to get waypoints. You can find further documentation here.

ROSBAG recording (not yet tested)

The carla_ros_bridge could also be used to record all published topics into a rosbag:

roslaunch carla_ros_bridge client_with_rviz.launch rosbag_fname:=/tmp/save_session.bag

This command will create a rosbag /tmp/save_session.bag

You can of course also use rosbag record to do the same, but using the ros_bridge to do the recording you have the guarentee that all the message are saved without small desynchronization that could occurs when using rosbag record in an other process.

Troubleshooting

ImportError: No module named carla

You're missing Carla Python. Please execute:

export PYTHONPATH=$PYTHONPATH:<path/to/carla/>/PythonAPI/<your_egg_file>

Please note that you have to put in the complete path to the egg-file including the egg-file itself. Please use the one, that is supported by your Python version. Depending on the type of CARLA (pre-build, or build from source), the egg files are typically located either directly in the PythonAPI folder or in PythonAPI/dist.

Check the installation is successfull by trying to import carla from python:

python -c 'import carla;print("Success")'

You should see the Success message without any errors.