Hi - I don't know if this is the right forum area, but, I was looking for a simple little robot that will change to a random direction if it hits a wall, and also, will remove itself from spaces if it goes under a couch or anything too low. As close to the size of a 9-volt as possible (of course, bigger is OK, but to give you an idea that I'm not trying to make something huge!). Also, it should be somewhat cat-proof and self-right. Ideas? Or, can I just go buy this somewhere?