[mowbot] Ken Reed's LawnBot

Dave Everett (deverett nospam at vir.idx.com.au)
Sun, 20 Jul 1997 21:06:46 +1000

After reading Ken's description about his robot I started thinking about
the possible problems of uncut grass detection.

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

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

Dave Everett.