I do not think that a sonar system will do much good trying to detect the
height of the grass. Grass is soft and would not reflect sound very well.
The blades of grass are small and widly spaced relative to the sound waves.
Using some kind of optical sensor seems more likely to work.
Why not use three optical sensor/emitter pairs located about 1 inch away
from and in between both of the front wheels just slightly above blade
height.The inside of the wheels is painted white. Two pair face out towards
the wheels the other pair gos from one to the other. Crude Diagram follows:
------ -------
| W | | W |
| H |<<<<<<<]E E[>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>]R E[>>>>>>>| H |
| E |>>>>>>>]R ________________________________ R[<<<<<<<| E |
| E | _____/ \_____ | E |
| L | _/ \_ | L |
| | / MowBot Blade Deck \ | |
| | / \ | |
To ensure complete coverage the MowBot just keeps the grass between
the center pair and no grass between eather the left or right pair.
This is kind of what I do when I mow. Have one wheel run just outside
the unmowed area. This should work well for following the cut edge
but won't do much for general navigation.
Of course we could make these for large yards. Kind of a helper MowBot
that would do the rest of the yard after the supervisor Mowbot trimed
the edges!
Ron