Workspace Setup

Create the Structure

$ mkdir -p ~/fav/ros2/src
$ mkdir -p ~/fav/ros2_underlay/src

In ROS, we put the code we write (or use) in so-called “workspaces”. We can have multiple workspaces and can either use them in combination by “overlaying” the workspaces. Or we can have them as completely independent setups and use only a certain selection of them at a time.

For this class, we use the two workspaces ros2 and ros2_underlay. As the name suggests, we use ros2 as an overlay to ros2_underlay. Of course there is a reasoning behind this.

ros2_underlay: We use this workspace for code/packages we want or have to build from source. However, these packages we do not modify regularly or work with at all. Outsourcing these packages into a separate workspace speeds up the compilation time of our actual development workspace.
ros2: This is our development workspace. We put all the packages/code developed during this class here.

1. “ros2_underlay” workspace

We will first setup the ros2_underlay workspace. The setup includes three steps:

downloading the code of the packages we want from e.g. github
building the code
sourcing the workspace, so that the built packages can be found by your machine and executed

Populate the “ros2_underlay” workspace

Let’s download the relevant packages

$ cd ~/fav/ros2_underlay/src \
&& git clone --recursive --branch fav-23/24 https://github.com/HippoCampusRobotics/hippo_core.git \
&& git clone --branch fav-23/24 https://github.com/HippoCampusRobotics/hippo_simulation.git

$ cd ~/fav/ros2_underlay/src \
&& git clone https://github.com/PX4/px4_msgs.git && \
cd px4_msgs && \
git checkout 8a7f3da

Build the “ros2_underlay” workspace

Create an alias for the build command for convenience

$ echo "alias build_underlay=\"env -i HOME=\$HOME USER=\$USER TERM=xterm-256color zsh -l -c 'source /opt/ros/iron/setup.zsh && cd \$HOME/fav/ros2_underlay && colcon build'\"" >> ~/.zshrc
$ source ~/.zshrc

Make sure dependencies are installed

$ cd ~/fav/ros2_underlay \
&& source /opt/ros/iron/setup.zsh \
&& rosdep install --from-paths src -y --ignore-src

Build the workspace (this may take some time!):

$ build_underlay

Note that by executing the defined alias, you do not have to be inside the respective workspace directory to build. Very convenient!

Source the “ros2_underlay” workspace

$ echo 'source "$HOME/fav/ros2_underlay/install/setup.zsh"' >> ~/.zshrc && \
source ~/.zshrc

2. “ros2” workspace

Now on to our development workspace. You will later on fill this workspace with your own packages. Exciting!

Populate “ros2” workspace

$ cd ~/fav/ros2/src \
&& git clone https://github.com/FormulasAndVehicles/fav.git

Build “ros2” workspace

Create an alias for the build command for convenience

$ echo "alias build_ros=\"env -i HOME=\$HOME USER=\$USER TERM=xterm-256color zsh -l -c 'source \$HOME/fav/ros2_underlay/install/setup.zsh && cd \$HOME/fav/ros2 && colcon build --symlink-install --cmake-args -DCMAKE_EXPORT_COMPILE_COMMANDS=ON'\"" >> ~/.zshrc
$ source ~/.zshrc

Make sure dependencies are installed

$ cd ~/fav/ros2 \
&& rosdep install --from-paths src -y --ignore-src

Build the workspace (this may take some time!):

$ build_ros

Source “ros2” workspace

$ echo 'source "$HOME/fav/ros2/install/local_setup.zsh"' >> ~/.zshrc \
&& . ~/.zshrc

Check `.zshrc` file

Note

The mysterious .zshrc file is used to set environment variables. Everyone sometimes makes typos or errors while adding stuff to this .zshrc file. You might open a new terminal and get an error as follows on the top:

bash: /...[file path+name]: no such file or directory

In case you echo (aka write) a wrong line into the .zshrc file, you can delete this line by opening the file in your favorite text editor. For example, using gedit as text editor:

$ gedit ~/.zshrc

The file should open in a new window. The command echo adds lines to the end of the file. Therefore, scroll to the bottom and find what you’ve added. Delete the lines that cause errors and save the changes.

Open the .zshrc file, for example using gedit as text editor:

$ gedit ~/.zshrc

Your ~/.zshrc should look like this this for the last lines:

...

source /opt/ros/iron/setup.zsh
alias build_underlay="env -i HOME=$HOME USER=$USER TERM=xterm-256color zsh -l -c 'source /opt/ros/iron/setup.zsh && cd $HOME/fav/ros2_underlay && colcon build'"
source "$HOME/fav/ros2_underlay/install/setup.zsh"
alias build_ros="env -i HOME=$HOME USER=$USER TERM=xterm-256color zsh -l -c 'source $HOME/fav/ros2_underlay/install/setup.zsh && cd $HOME/ros2 && colcon build --symlink-install --cmake-args -DCMAKE_EXPORT_COMPILE_COMMANDS=ON'"
source "$HOME/fav/ros2/install/local_setup.zsh"

Final Check

Are we sure that everything is prepared correctly? Let’s check it!

$ ros2 launch fav simulation.launch.py vehicle_name:=bluerov00

If a window similar to the following opens, we are on the right track

If things do not work out as you hoped, please read the terminal output carefully and check for errors. If you cannot figure out the problem yourself, send a copy of the complete output to your favourite research associate. Preferably via Slack. And use the code-block function there (Ctrl + Alt + Shift + C). This really helps us to help you!