Perhaps stated more accurately as: Choose when to milk themselves. A robot does the actual act of milking. With context of robotics already setup, I made assumptions based on that when making that statement. If I said that around farmers, they'd know exactly what I was talking about. I guess that goes back to being able to speak the language of the people you are interacting with.

But if you're looking for more general information: http://en.wikipedia.org/wiki/Automatic_milking