It obviously has gyroscope(s), since it can't be toppled. It recovered nicely when an attempt to tip it over was made by kicking it. But I say it must be controlled to some extent because it went up the hill toward traffic on a street (how would you like to be driving along and see this thing coming out of the woods?), then turned and went back down the hill. The speed at which it moved was somehow regulated, as well as the direction.
Google "robotic pack mule" and you'll find that is, indeed tested by the military and Google owns the company developing it. It can carry 400 pounds and travel 20 miles in a day without "refueling". My quick look didn't determine what powers it.