iRobot-My little sweeper roams around the hardwood floors, vacuuming up dust and crumbs, bumping gently into chairs and doorways. Undismayed, he nonchalantly backs up and simply pirouettes to continue in another direction. Invisible rays emanate from the two white towers, fooling him into thinking a wall is there. He makes a quarter turn and on he goes until he reaches my area rug with a dark border. He thinks it's a cliff and stops dead in his tracks. I let him think it over for a few moments and then send him back to recharge at his battery dock.