Navigator

Navigator is a simple, end-to-end, and open-source autonomous driving framework.

Why Navigator?

Despite major advances in autonomous driving research, there has yet to exist a single framework that is both simple and extensible, all while being public and transparent.

Navigator is our answer to this delimma. It’s built on standard technologies, is kept as simple as possible, and its modular design makes adding new features straightforward.

System requirements

Docker
CARLA 0.9.13 for simulated testing (optional)
For best results, a dedicated GPU with at least 6 GB of memory, ideally 8 GB
x86_64 CPU
About 20 GB of disk space

Installation

Note: Lines with “$” are on host, while lines with “#” are within the container.

Install Docker.

Nova Members: Docker is already installed on the Quad.
Choose a number between 0-100 and use this for your user-wide ROS_DOMAIN_ID environment variable. Add the following line to your .bashrc file
```
export ROS_DOMAIN_ID=57
```
Clone our repository (checkout the dev branch if you plan to do development, or main if you want the most recently release)
```
$ git clone -b dev git@github.com:Nova-UTD/navigator.git
$ cd navigator
```
Any contributor: If simply running the stack is the goal, then checking out dev or main can make sense. If you aim to contribute, you should create your own fork of the dev branch and check that repository out instead. More details about contributing can be found here.
Build our Docker container. The sequence of commands used to build the container is given in the Dockerfile file and the build and run parameters are specified in the docker-compose.yml file.
```
$ docker compose build navigator
```
Nova Members: A Docker image for Navigator already exists on the Quad, so there is no need to rebuild it (unless you’ve changed it!). Other Users: Some customization of the docker-compose.yml file may be needed to link it up with your installation of Carla. You should be able to build the image without doing that first.
Run the Docker image. Here we are specifically launching the container so it is configured to run with the CARLA simulator:
```
$ docker compose run navigator_carla
```
Now that you’re in the container, build the navigator ROS workspace:
```
# colcon build --symlink-install
```
That’s it!
Note that if you’ve build the workspace outside the container or want to start with a fresh build, you can delete the build, install, and log directories and call colcon build with the following extra flag:
```
# rm -r -f build
# rm -r -f install
# colcon build --symlink-install --cmake-clean-cache
```

CARLA Simulator

Make sure you’ve installed Navigator using the steps above.
On the host, start CARLA: ./CarlaUE4.sh See the CARLA docs for more info. Note that CARLA runs natively on the host, while Navigator and the CARLA-ROS2 bridge run in (separate) containers. Currently it is standard for Carla to output the following, which looks a bit like an error, but is fine:
```
chmod: changing permissions of '/home/share/carla/CarlaUE4/Binaries/Linux/CarlaUE4-Linux-Shipping': Operation not permitted
4.26.2-0+++UE4+Release-4.26 522 0
Disabling core dumps.
```
Nova Members: On the Quad, CARLA is installed at /home/share/carla/, so you can add an alias to the .bashrc file with the line alias runcarla="/home/share/carla/CarlaUE4.sh". The preferred way to interact with the simulator is to run it offline and also on a unique port. You can add the following lines to your .bashrc file to make this the default (notice that this uses your ROS_DOMAIN_ID to make the port unique):
```
export CARLA_PORT=$(($ROS_DOMAIN_ID+2000))
alias runcarla="/home/share/carla/CarlaUE4.sh -carla-rpc-port=$CARLA_PORT -RenderOffScreen"
```

CARLA-ROS2 Bridge

The current CARLA-ROS2 bridge, that allows ROS to communicate with the CARLA simulator is compatible with ROS2 Foxy, not the ROS2 Humble we use for Navigator. We use a second Docker container to run the CARLA-ROS2 bridge.

The docker files and ROS packages that act as the interface between Navigator and CARLA are located in the carla_interface repository. Clone this repository using a new terminal window:
```
$ git clone -b dev git@github.com:Nova-UTD/carla_interface.git
$ cd carla_interface
```
Similar to Navigator, the Dockerfile and docker-compose.yml files in the repository let you build the image:
```
$ docker compose build carla_bridge
```
Nova Members: The Quad should already have an image for this Docker container built.
Run the Docker container:
```
$ docker compose run carla_bridge
```
The entrypoint.sh script (in the /docker directory) sources ROS2 (Foxy) and sets environment variables needed for the bridge.

Launching a Demo

Launching a demo requires three terminal windows. Recall $ are commands run on the host and # are commands run in a container.

In the first terminal window, launch Carla using runcarla (assumes you set up the alias described above).
In the second terminal window, run the CARLA-ROS2 bridge container (should be in the carla_interface respository root directory) and then launch the carla interface nodes:
```
$ docker compose run carla_interface
# ros2 launch launch.carla_interface.py
```
In the third terminal window, run the Navigator container (should be in the navigator respository root directory) and then launch the Navigator stack:
```
$ docker compose run navigator_carla
# ros2 launch launch.carla.py
```
Note: The node definitions for the Navigator launch script are located in the file launch_node_definitions.py.

Real-world use

To run in the real-world, you’ll need to provide your own LiDAR stream, map data, and throttle/brake/steering interface. We provide our own interface, for use with our specific hardware, as an example.