Hi all - a mate of mine down the road has one of the self do it all mowers.  When I went to his place I said what is that giant cockroach on your lawn?  It is my lawn mower.  There is a wire barrier around the lawn and when the mower gets to it, it reverses and goes in another direction.  Disadvantage though, it doesn't have a catcher.  My dearly departed Dad wanted to invent a self-drive mower that was attached to a rope attached to a stake.  As the mower drove it would, like the legendary Haggis Bird, travel in ever decreasing circles until it disappeared up its own clack.
 
 Bob