This project shows how to develop and run your own V2X (Vehicle-to-Everything) application on the cube-its in a ROS 2 (Robot Operating System) environment.
ROS 2 is known as an advanced middleware for creating software for self-driving robots and even autonomous vehicles. It has a decentralized setup with nodes handling specific tasks, such as processing data from a single sensor etc. Since we will be working with ROS, it makes sense to get familiar with the environment and features of ROS.
The cube-its is a collection of software tools, ROS 2 nodes and components and that provide functionalities for V2X (Vehicle-to-Everything) services, including facilities like CAMs (Cooperative Awareness Messages), DENMs (Decentralized Environmental Notification Messages), CPMs (Connection Protection Messages) and more. Additionally, cube-its can serve as a platform for development, deployment and operation of ITS applications and beyond.
- CUBE EVK running the cube-its framework
The sample application features a simple ROS 2 node named cam_listener as shown in figure 1. This node listens for received CAMs transmitted through the designated published topic "/vanetza/cam_received" by cube-its. The cube-its framework handles the publication of received CAM data, while the cam_listener node is configured to subscribe to this specific topic. This configuration enables the cam_listener node to efficiently receive and process the CAM data, showcasing a fundamental aspect of the project's functionality.
The cam_listener node operates within a Docker container, similar to the cube-its. Both are functioning within a ROS 2 environment and share the same domain, facilitating the ability of ROS 2 nodes to discover each other.
By default ROS_LOCALHOST_ONLY is set to 1, which means that cube-its, its topics, services, and actions will not be visible to other ROS 2 environments on the local network. By setting ROS_LOCALHOST_ONLY=0 enables cam_listener and cube_its to discover each other, if they share the same domain (default: ROS_DOMAIN_ID=42). You can simply disable the localhost only setting by typing in a terminal:
export ROS_LOCALHOST_ONLY=0
In other words, they are part of the same ROS 2 environment, and the cam_listener node can now access to all services and topics of the cube-its.
In the same way, it's possible to set the domain to a different value:
export ROS_DOMAIN_ID=45
More information about domain ID can be found here: https://docs.ros.org/en/humble/Concepts/Intermediate/About-Domain-ID.html
You likely already have open the devcontainer project with VSCode (Visual Studio Code). If you are not familiar with developing inside a container, check the following link https://code.visualstudio.com/docs/devcontainers/containers before you start.
Navigate to the root of the workspace, dev_ws:
cd dev_ws
Build application by:
colcon build --packages-select v2x_apps
Still in the same terminal, source the setup files:
source install/setup.bash
Now run the cam_listener node:
ros2 run v2x_apps cam_listener
The node is running correctly when you see the following terminal output:
[INFO] [1706013094.349399714] [cam_listener]: Node "cam_listener" started
The cam_listener is now waiting for a received CAM message by cube-its. When cube-its starts receiving CAMs, cam_listener will output on terminal:
[INFO] [1706013095.341824275] [cam_listener]: Received CAM from Station Id: 84281098
[INFO] [1706013096.345854233] [cam_listener]: Received CAM from Station Id: 84281098
[INFO] [1706013097.345731609] [cam_listener]: Received CAM from Station Id: 84281098
[INFO] [1706013098.345113236] [cam_listener]: Received CAM from Station Id: 84281098
[INFO] [1706013099.344528362] [cam_listener]: Received CAM from Station Id: 84281098