[mowbot] mowbot itenary - my plan (sorry for length)

DON AUTRY (Don.L.Autry nospam at msfc.nasa.gov)
07 Oct 1996 09:06:21 -0500

My bots name: Baa-Bylon 1,2,...

My yard:
105'w x 400' which yields right at 1 acre. 3/4 of it mown, 1/4 wood
Very complicated. fencing diragram below - not to scale

. .
. .
. .
| Heavy Woods |
|_________ * ___________| * yes, that is a hole in the fence,
but it is
| | woods, not mowbots concern.

| 1 | 1 decaying barn
| | (need matches)
| |
| used to have bio goat |
| | |
| | |
| G G
| 2 | | 2. old well house
| | | (need dynamite)
| Fred's yard | garden |
| | |
| 3 3 | | 3. metal storage sheds
| | |
| | |
| | |
| | |
| 4 | | 4. Fred's house
| | | (need new dog)
| | |
|G_______________| |
| house | |
| | 5 | 5. Satellite Dish
| | |
| | 6 | 6. AC UNIT

G = Gate

There are also numerous trees in Fred's yard and the bio goats area.
Goes from open to woods real quick.

The garden area is mostly open with a couple small trees and
sometimes a garden. I separated it from Fred's yard when he ate the
AC unit. Don't suggest taking fence down. It cost me $500 bucks to
replace the condensor.

There are also raised beds scatteered thru out surrounded by landscape

Also may get another bio goat for the woods. They are great for
controlling poison ivy and honeysuckle.

Additionally across the front and next to the street is a 4' deep
ditch that runs across the front of the property. The incline is
steep as the county really fouled it up with their backhoes 2 years

Mowbot Shape:

/ | \
| | |
| | |
| | |


The pointy front will move pinecones and small sticks out of
the way. The front can be tapered from tip to top to facilitate
getting under low branches etc. Actually a cow catcher type
attatchment will work as well, but solid less likely to tangle.


a little over 1 foot wide to give a a 12" or so cutting width.
Size will actually be determined by motor strength and costs etc.
Also how long motors can run, battery size, etc. See a twin blade
arrangement powered by one motor.

Cutting Rate:

I Made the following objectives: Cut yard once a week.
With the biobot method I can actually get by with every other
week, but aren't we striving for manicured?

Given rainy seasons beginning of spring and fall I figured I can
count on at least 3 good days of weather to mow.

Accepting posts here that say you have a 2:1 charge to work rate,
That gives 1 day of actual mowing. This is really very restictive.
Rains tend to come and go. Wet in morning or afternoon, Dry at other
times of day. But I like to be mean in my
specs. I also doubt the 2:1 ratio. Think it might be more like

Figuring that a 12" actual cutting radius can be achieved, +
on blade width for overlapping runs.

400' x 100' = 40000 square feet.
divide by 24hours/60minutes/60secs i got around a half a cubic
foot per second.

Especially since I only have 3/4 acre to mow.


Weed Terminator blades. These are small 3" long nylon plastic
blades which are advertised on TV here in the states. They replace
that stupid weed eater line that constantly breaks and will not
feed properly with any product that is on the market. They are
also available at lowes and maybe home depot. I bought the unit
for my weedeater to cut the ditch cause that nospam at #$%%#$$ line always
breaks and misfeeds. They are very durable and last for a few
mowings but do suffer when you are beating the edges against the
metal drainage pipe under the drive, or the house, fence, etc.
I think they would last a whole season in a mowbot. Blades can be
bought for only a couple bucks. They work centrifically so if
they hit something they bounce back away from it. might break
bare skin, but when I hit my leg, wearing pants, It hurt like
hell but did not cut a gash in me or cut the pants. This only
happened once and the eater was not at full speed. It was also


Electric of course.

Don't want no robot with compustibles running around the place.

Don't want neighbors to hate me when it decides to mow at 2:00 am.

Don't want to be woken at 2:00 am by mower, or before 2:00 pm
on a weekend when hung over and/or snuggling with some honey.

A gasoline robot is like owning a pit bull instead of a Fred.
A lawsuit waiting to happen.

It is supposed to work without my help! I don't want to run to
the store for no damn gas.

6 or 12 volt systems for 2 reasons.
Very standard to find motors etc.
Can use car or motorcycle battery for testing

Will go to better and more expensive battery later as I don't
want acid leaking when mowbot flips in the ditch.

Design and Testing Stages: ( the nitty gritty )

Baa-Bylon 1
Run around in Fred's enclosed fenced area at random
cutting grass and tormenting fred, or being tormented by
fred. Only sensors needed
will be like that dumb little tank I had as a kid that bumped
into walls and turned around.

Released by hitting on switch, chased down and turned off
and put up. Or allow to run down.

Test motor strength, durability, battery life, etc.
Simple 1" pvc frame with optional 1/4" plywood body, and lawn
mower wheels.

Determine and get right motors, blade configuration, size, etc.

Release thru ditch and watch it flip. Find out power needs, sizes of
wheels, frame proportions, etc. to avoid flips. Won't need blades
for this. Just drive mechanism
and pvc framing. Won't even need body for this part.

A amusing little toy for research purposes.

Baa-Bylon 2

New Frame, Cheap, maybe same type construction, but must be
water resistant.
By now I should have a good idea of final size and configuration.

Transplant Brain. A 386 perhaps as that would be easy for me.
Big Step for me, I know nothing about micro controllers,
electronics, or which end of the soldering iron gets hot.
I am a programmer not a injuneer. Actually I have soldered
rca connectors for wiring. My mother had to show me how
though. That's why I like the idea of a PC on wheels. I understand it
and it seems as cheap as some of the boards I have seen ready made.

Build chargeing station.


Will seek food when needed.

Add a wash hands before dinner logic. Build cleaning
station wich sprays water for 1 - 2 minutes while bot spins.
Fred leaves lots of interesting little presents for the
bot to find. Not to mention F.O.C. (Flying Organic Crud)
Need to keep bot and station clean.

Add I. R. detection of mowed vs. unmowed to start actually
follow edge of mowed area. I actually understood you guys
on this area, I have a mouse that works like this.

Add blade cutoff if area traversed needs no mowing. Save power.

Add run, wash up and hide from weather. Moisture detection sensor.
This may actually not be necessary with a manicured lawn and a
Waterproof bot.

Baa-Bylon 3

Final Body (I hope). Angle Iron Frame, Sheet Metal or plastic covering.
Completely Waterproof. Personnally I like platic covering.

Add obstacle detection before bumps (No use in it beating its
brains out)

Add cat whiskers and/or spring wheels.

program hugging behavior to follow fences, trees, sheds, etc. using
whiskers and/or wheels.

Add counters to drive mechanism for measuring purposes.

Add mapping program to map and remember environment and know where
it has been, and where it hasn't been. Also learns
where it can't go, like in a storage shed.
(ain't you put enough damn dents in that thing yet?)

Add detection for no cross lines, like the garden. Perhaps buried
wire? or IR beam.
(oh no, not the tomatoes again)

Add sensors for blade deflection and hook to speed control to insure
even mowing.

Hey, It almost looks like it knows what it is doing. Dump That
damn weedeater.

Baa-Bylon 4
Put final batteries in. Don't want acid to get on works when it
flips in ditch. And it will I know.

Add tilt and precipace sensors to avoid ditch completely.

Add ultra sound, and color detection for pavement rejection
and to avoid gravel, except driveway traversal (Need a bridge).
(Honestly officer, I don't know how that orange relfective stripe got
painted on the edge of the road right in front of my house.)

Add code to stay out of front yard except when I should be

Add ability to change zones by itself.
(I sure am sick of moving that thing around by now.)

HMM. any idea how to build a gate that mowbot can go thru and
Fred can not?

Baa-Bylon 5

Mow that damn ditch. And stay out of the street.

Now I will be really happy.
Mowbot is essentially complete.

Anything beyond this point is extra gravy and doesn't figure into
original budget of 500 - 600 bucks, but if I have got here
with < $1000 U.S., I will be more than ecstatic.

Baa-Bylon 6, 7, etc. (Just some possibilities, some are a little

If cutting capacity allows, run across asshole's yard next door
and mow the yard a couple houses away. He has serious cancer
problems and can't mow it himself. This is the county though
so all the neighbors around here seem to take care of it for him.

RF transmitter - for locating stolen unit.

commuication with base station (home PC) thru RF transmitter.
That little onboard map sure would be nice for landscape

call base if stuck or flipped in ditch
(Help, I've fallen and can't get up)

check with base every so often and report okay.
Base would call me if he disapppears.

cooperation thru base station if more than one unit becomes

connect to alarm system if lifted.

Release from limitation to stay out of front unless I am home.

pick up trash in ditch and dispose of it.

pick up pine cones and sticks and put somewhere.

Recognition of Pets, me, and intruders.
(real world limitation would make the little girl next door
show up as a pet, that is acceptable. Don't want mowbot
messing with neighbors pets or little kids. Perhaps he
could know me by a ring or something.)

quick cam photos of intruders
Send photos to base.

bitch at intruders.

respond to call to arms from base station detection of perimeter

water spray of intruders, fred.
reload water and pressure chamber at charge station.

Feed Fred.
(Fred - "Is he gonna feed me or spray me?")

Recognition of UPS. meter readers, and salesmen.
Recognition could be programmed by the behavior of the
intruder. Where they go, etc.
(Electric Guy "If that damn thing sprays me one more time!
I'm gonna...")

call me on intruders (base station would actually do this).

call cops on intruders.
(wonder If there is a way to detect a strobe light from a
emergency vehicle?)

capacitive discharge to shock anyone or fred messing with it.
Them little handheld tazers are awful cheap now.

attack and shock intruders. Maybe a goat head with metal horns.

tazer that burgler's butt when he is half in the window.
( I need a volunteer to test this, any takers? )

Occasionally go into berserker mode and attack the asshole next
door in his own yard.
( Gee, I wonder how that happened? ;) )

the list goes on and on.

Final Notes and Questions.

Well, I have now proposed a agenda. Of course it is a little rough
and I apologize for the length. I believe it addresses the type of
concerns and the general things
we need to deal with in a logical order. It also won't cost a
fortune since many
of the materials in early stages are so cheap. At least it is a
agenda that will
work for me. I am willing to share anything I learn from these
experiments of course,
after all, I will actually be siphoning much more knowledge from

Does anyone out there have some motors or batteries or other things
collecting dust
for testing? I have many things, and don't mind buying some, but
don't want to be
eaten up buying and testing motors and batteries to determine the
requirements we
will need. You injuneers may be able to supposedly calculate it,
but that is all
mumbo jumbo to me. I am limited to trial and error. That could get
expensive. This is where I need your help. HELP!

Now for some Questions: (Putting on flame retardent suit, some are
probably stupid but all of them are real.)

Will ultrasonic transducers upset a dog's ears? I would hate
for Fred to start
howling every time mowbot goes to work. He hates cop cars.
The electric guys here also carry a ultrasonic do hicky
that keeps dogs at
bay. Will that thing blow mowbots mind?

Will sensors go straight into 386 type boards i/o ports, or
will I need something.
If so, what, and how much?

Ideas for dog proof, but mowbot accessible gate?

Do buried wire lines require power?, if so how much?, can they
work DC for backup?
How expensive is this stuff?, That damn dog fence cost more
than mowbots budget.

How can 2 PC's communicate by RF. Any off the shelf type of
stuff? I know there
is a standard for I.R., but there are many trees, sheds, etc
in this yard.

Could a sensor be built cheaply to detect a strobe light like a
cop car. Program - Shut down stupid, your about to get shot.
Or I am lieing half dead inside with a heart attack, let them in
you fool.

Is there anyone out there willing to show me how to build
circuits in a way that a idiot like me can understand?
I don't speak squiggly lines like yall do.
I make the average radio shack employee look smart when it
comes to electronics. (but not by much)

A final statement:

Forgive the line wraps, lots of editing. kept it at 80 cols
but if line got shortened I did not reformat it. Used
notepad to keep it simple ascii. Lets all do the same.
Never upload a .doc, this causes word to do its 30
minute load up here at nasa. any attachments should be
named .txt. avoid attatchments as much as possible as
well. This I hope does not show up as one. Some of you
guys have email that comes to me as attachment unnamed1.
It is a pain to click thru the hoops to open these at
nasa. Also, if your gonna respond to the group, don't
also respond to the individual. This is wasteful.

Thanks in advance to any positive statements or answers, as
for flames, well I got my asbestos suit on so fire away.