I am thinking of launching a project of a DIY lawn mower robot like http://www.youtube.com/watch?v=HgUxh44jGbs
The downside of existing solutions is that it requires you to define/surround the yard with a cable to prevent the mower from escaping the area.
My idea would be having a couple of RF antenna poles and a multi-channel receiver on the mower which reads the phase shift of those antennas for position calculation.
Accuracy would need to be about 2-3 inches in a normal-sized lawn yard.
Is there any existing project that include position detection already (without GPS with its rough resolution)?
Your feedback would be very much appreciated.