Re: [mowbot] Motors arrive

Byron A Jeff (byron nospam at
Mon, 3 Mar 1997 09:39:31 -0500 (EST)

> The gearmotors I ordered from All Electronics finally arrived. As
> advertised they draw about 600ma without load and appear to have
> excellent torque. I am having the wheel couplers and mounting plates
> made by a small parts manufacturer and they should be ready in about a
> week.
> When the parts are ready I will post some pictures of how they go
> together. The scheme removes all the weight loading from the motor and
> drives the wheels through some sealed bearings.
> In a few weeks I won't have any excuses for sitting on my arse :-D

I was going to come in a post this morning too. It has been raining like
crazy here in Atlanta and there have been record highs (80 degrees!). Little
tuffs of grass are starting to pop up! Sigh!

Anyway just to re-interate my agenda in priority order:

1) Mobile platform than can move in a straigt line at up to 25o incline.
2) Cutting tool that reasonably cuts grass.
3) Everything else (edge detection, low power go home and feed circuit, auto
grass cutting)

A couple of weeks ago I was intently examining a childs 16 inch real bike
wheel. It seemd to be real easy to mount, uses a standard bike chain
(obviously) and seemed really sturdy. Does anyone have any comments on the
possibility of driving a pair of wheels with gearmotors such as above. Of
course the gearing for bike wheel are such that they only drive in one
direction, the other causes braking. However it seems to me that steering
can be accomplished by stopping one wheel and driving the other, which would
effectively spin the bot around the braked wheel.

Here's a couple of really crufty ASCII pictures to illustrate:

Top view

- ************* -
- * C * -
- * * -
- * * -
- * M M * -
- * * -
- * * -
- * C * -
- ************* -

^ ^ ^
| | |
Wheel Body Wheel

Where the C's are a couple of castor wheels that spin freely so that the Body
will remain off the ground.

Back View

- -
- -
- -
- -
- -
- g g -
- c c -
- c c -
- c c -
- G G -
- G MM MM G -
- G=MM MM=G -
- G MM MM G -
- G***********************G -
- CC -
- CC -
- -

M - Motors and motor mounts
G - Gear connected to motor to drive wheels
g - Gear connected to wheel
c - Chain to connect the two sets of gears
C - Castor wheels. Could have 4 set in corners too.
* - Body

You get the basic idea. I figure if the body is wide enough that it'll be
difficult to tip it. I have it low to the ground to keep the Center of
Gravity Low.

This isn't real well thought out. I'm not a mechanical type guy. I mostly
do computers and electronics. But if I can put together a platform that can
wander around in my yard then I'm moving a lot closer to a MowBot.

Any updates on cutting technology? Anyone consider simply using a real
lawn mower attached to a base such as above. Real lawn mowers definitely
have the correct cutting technology, they just don't have the correct
platform for autonomous (sp) motion.

Comments and criticisms welcome. Put it right back here on the mailing list
so we can bounce it around.

BAJ (the clueless yet eager one)