>c. Is there a simpler way?
>
>David
Yes, there is a simpler way, David. LOSE the precision control, and don't
worry about trying to precisely position your mower 4" from the last cut.
Your mower will wander all over the place even if it is trying to go
straight. The easy answer - let it wander. Come up with a scheme
(barriers, buried wires, whatever) that keeps your mower in the yard, and
just mow randomly.
Sometimes it will re-cut an area, sometimes not. So what? Drink lemonade
while watching it mow. The simplest scheme is just a barrier (even a row of
stakes will do) all the way around the yard. Sense them with bump sensors.
You can add wheel sensors if you have any bid holes, ditches, etc., but if
you have a simple yard, just let the thing wander around like a goat.
(GOAT stands for Grass Omnivorous All Terrain Robot. That's the name of my
project.)