Re: [mowbot] drive and chassis design

robin nospam at
Fri, 25 Oct 1996 20:48:10 +0100

DON AUTRY <Don.L.Autry nospam at> wrote:
> ... A tracked system
> would be great for me as I have that ditch to contend with, and I may have
> to build a tracked bot for it, but I have not been able to come up with a
> way to mow close to a edge with a tracked system.
One way would be the soultion used by the Koala robot (see the web page
link I posted very recently)---in its guise as a vacuum cleaner, it has
the sucking attachment on an arm in front that it can swing to and fro in
a very fluid and controlled way. I don't know how many joints it has,
but from the short mpeg animation it looks as if it has two, so it can
easily get it in to corners.

> The chassis could be anything, but I believe a design which is simple to
> build is ideal.

> A dome shape would be perfect as it would be self righting
> if mowbot should flip, but these shapes are hard to build unless you are
> handy with fibreglass.
Aargh! That's quite a feat. The centre of gravity would have to be
really low to make that trick work, and if it was that low, I can't
imagine mowbot could flip without outside intervention.

Clear plasic domes are available quite cheaply from Edmund Scientific
(whose catalogue is full of wonderful things incidentally).

> Another good material for the enclosure would of course be platic, but I
> have never seen a place where you can just buy sheets of it cheap.
I got mine in a place that cuts melanine and such things for fitted
kitchens. Because I bought off-cuts it was very cheap.

> Another idea I had for a cheap, easy way to make the blade decks was to
> get two melamite, (cheap plastic) salad bowls about 7-8 inches diameter.
> Cut about 1/2 inch of one edge each, and join them. drill a hole in the
> center for blade drive shafts, use two pluming grommets on each side
> of the bowl on the drive shaft, and mount a pully on the back, and
> blades in the bowl. voila, cheap weatherproof blade decks. Now you only
> need to cut round holes in your bottom sheeting material and glue them
> in.
I like this idea. If we had something a bit bigger, perhaps we could get
away with just one. How about the sort of bowl one might put in a sink?
That's about 0.4m (15 in) across and they come in round and oblong
flavours. Inverted, such a bowl would make a splendid weatherproof roof.
We would still need to seal the bottom, but that would be an easier
problem since it could just be a plain sheet of aluminium or perspex
or whatever cut slightly smaller than the bowl so it fitted inside:

# #<--plastic bowl
# works #
# ------------<#---sheet metal base
## ##


Copyright (C) 1996 R.M.O'Leary <robin nospam at>  All rights reserved.
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