For several reasons, socketcan bridge/interface pkgs were directly included in the repo.
They shouldn't be there, although there were reasons to be there.
Can just be installed with sudo apt install ros-melodic-socketcan-bridge
OR, if properly specified in the package.xml (of robot_control), just use rosdep install.
http://docs.ros.org/independent/api/rosdep/html/
(This is the (if done right) easy way to install all dependencies for a project, as they'll already be up-to-date (I hope I hope) in each package's package.xml file; furthermore, it shouldn't compile if it doesn't have the minimum packages installed).
For several reasons, socketcan bridge/interface pkgs were directly included in the repo. They shouldn't be there, although there were reasons to be there. Can just be installed with sudo apt install ros-melodic-socketcan-bridge OR, if properly specified in the package.xml (of robot_control), just use rosdep install. http://docs.ros.org/independent/api/rosdep/html/ (This is the (if done right) easy way to install all dependencies for a project, as they'll already be up-to-date (I hope I hope) in each package's package.xml file; furthermore, it shouldn't compile if it doesn't have the minimum packages installed).