When I was about 15, I 'modified' my Dad's lawn mower to mow by itself. It was a lot simpler than RC. Just one motor which drove the wheels and another driving four cams, two at either end. I had a pair of rollers one in front and one behind the mower. When a roller dropped off the edge of the grass, it stopped the wheels then turned the turned the cams a few revolution. Each revolution, the cams lift the mower and move it sideways a few inches. The drive motor then reverses and runs until it repeats the sequence on the other side. It had no intelligence, just a couple of timers and did an OK job!

Unfortunately my dad didn't really see it as the cool thing I saw - more me tinkering with HIS mower! He (in a somewhat angry manor) suggested that the junk be removed as he enjoyed mowing the lawn! Now somewhat older than he was then - I can see the cathartic nature of mowing and would probably be similarly displeased! (though - as a die hard techie, I doubt I could stop myself smiling and helping to 'improve' it!). Dad was no Techie!

The Cams were driven by an car electric window motor & box IIRC - and the drive from a kids electric ride on tractor which I procured from somewhere!