I know the ones your asking about. They are actually sweepers and not vacuums. These are the little round units that run around by themselves. They work pretty good, but on carpet you will need to run the vacuum on occasion as stated above because it just sweeps.
Many years ago a company made a vacuum cleaner that used the air blowing out to make the little round machine float on a cushion of air, like hovering. That company was named Hoover, they sold so many all vacuum cleaning machines became known a Hoovers. Actually they worked fairly well.
Vacuum cleaners are also known as hoovers. The US call the action vacuuming and The UK hoovering.
