IR pairs, like those used in the LawnRanger, could become clogged or
blocked by loose grass blades or mud. Ken says he has also tried mechanical
detectors.
Anyway I finally decided to read the Solar Mower patent that I put on the
website some months ago and discovered that the inventor used the strain on
the cutting mechanism to detect uncut grass. Ken's robot has 2 cutting hubs
so that provides even more feedback. My own design will probably
incorporate 3 hubs.
Using a simple current measurement from the cutting motors should be all
that's required, one current value for no load , another higher value for
uncut grass.
The other advantage is it simplifies the design by utilising an existing
mechanism as part of the sensory system.
As soon as possible I will perform some experiments and add them to the
website.
Dave Everett.