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.
ROS Lunar is available in AUR packages and seems to be working quite nicely although it lacks some simulators of theAUR package, the AUR is complete and seems to have everything functional.
Kinetic packages on the AUR are a work in progress. There are some issues regarding opencv3 that have not been fully resolved yet. That said, installing a metapackage such as AUR or AUR should bring in all required dependencies (see  for the correct order).
Packages are being added on an as-needed basis. Please send package requests to <aur AT seangreenslade DOT com>, and post any issues with the current packages in their respective AUR comments section.
Configure the build tool
Note that catkin uses python2, and therefore catkin_make may fail unless it it explicitly pointed to the python2 install. To do so, add the following alias to your .bashrc (or equivalent):
alias catkin_make="catkin_make -DPYTHON_EXECUTABLE=/usr/bin/python2 -DPYTHON_INCLUDE_DIR=/usr/include/python2.7 -DPYTHON_LIBRARY=/usr/lib/libpython2.7.so"
When you update a library that ROS depends on (e.g. Boost), all packages that link to it must be rebuilt. Most AUR helpers will not detect this situation. The following script will generate a list of all packages that are linked to missing so files:
(Note that the script requiresto be installed.)