Roomba-style efficiency

I've always wanted a Roomba, but I've decided to spare my neighbors the daily annoyance of it's whirring, buzzing, and banging into things. Plus, the wires connecting everything in my room create a rats-nest that would certainly ensnare any hapless robot that tried to traverse them.

Their algorithm for (essentially) blindly wandering around a room and managing to cover every area has always been a mystery, and this long-exposure photo of a Roomba at work sheds no light on it.