Here is a photo of a self vacuum:
https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQseXEStA1UJ40xYB35UTh...Here is a video as well. (it is long you dont need to see the whole thing just watch a little of how it moves)
https://www.youtube.com/watch?v=6tlFbSp5d0c