switch like this, but not the second one, so I desold-ered the pot from one of its left-right joysticks (
channel 3, I think) and replaced it with a small DPST switch,
mounted to the front of the transmitter.
If you connected everything correctly, you should
be cutting grass right now.
V Operation To operate the Lawnbot400, turn on the transmitter and flip the power switch on the bot. The Arduino breakout board should power up and the Neutral indicator lights on the R/C control should come on. These LEDs, connected to Arduino digital pins 12 and 13, indicate when the signal is in the neutral range. If they aren’t lit, adjust the trim on the transmitter until they are.
Time to crank up the lawn mower engine, and
remember to prime the bulb. Flip the switch for the
fail-safe channel on the transmitter, and the motor
controller should power on, along with the cooling
fan. Now all you have to do is drive.
Photograph by Robert Rausch (V)
The Lawnbot400 will scoot across the yard at
5mph–10mph, which may be faster than optimal for
mowing the grass. Proper cutting speed depends on
the power of the lawn mower engine and the condition of the grass. If you use the cheapest mower
available (like me), the engine will bog down if the
grass is too tall or wet. But if you mow before it gets
too tall, you should be able to go as fast as you want.
With a little practice, you’ll learn to adjust the speed
based on the sound of the engine and how hard it’s
working. At worst, the mower dies and you drive the
bot back over to you to restart it.
My fears about the bot’s ability to pull itself up a
large hill were put to rest when I took it to a friend’s
property and watched it devour ¼ acre of woods
with no problems. I was further convinced when
it carried me (155lbs) across the yard and up a hill at
a reasonable speed, without a hitch.
How about adding ultrasonic sensors, wireless cameras, and an XBee wireless link? I got an ArduPilot
with GPS for Christmas, so we’ll see what happens
there. I also plan to connect an electric motor to
the lawn mower drive shaft to charge the batteries,
which will also act as an onboard electric starter for
the engine in case it dies during operation.
To automate the process, I’d start by mowing the
grass with the R/C remote while using a GPS logger
to record its movements. Then the ArduPilot would
guide the Lawnbot through the recorded GPS path,
using sensors to keep it from hitting anything the
GPS didn’t catch. Of course, I’d be inside, watching
via camera while enjoying a cold beverage.
Find parts lists, schematics, code, and videos of
the Lawnbot400 at
J.D. Warren is a 27-year-old apartment manager and
electronics hobbyist from Pinson, Ala., who spends most of
his free time with his wife and three kitties or tinkering in