ROS is an open-source, meta-operating system for your robot. It provides the services you would expect from an operating system, including hardware abstraction, low-level device control, implementation of commonly-used functionality, message-passing between processes, and package management.
Setup Notes - Groovy
Currently, groovy is the only (semi-)supported ROS release that has Arch packages. The core, comm, and robot variants have meta-packages that should install all the necessary packages:AUR, AUR, (TODO: robot metapackage). In addition, AUR (along with its dependencies) has a package. Beware, the dependency tree goes at least five levels deep at times. AUR handles it OK, AUR falls flat.
The packages are all available in the maintainer's github: arch-ros-stacks. Not all packages there are in a working state, so use with caution. Please, report any issues with the packages on their respective AUR pages.