Robotics can have such distractions! My major project is
still to build 3 identical robots who's ultimate task is to
cooperatively collect and sort colored M&M candies, peanut
M&M's specifically. Thus I'll be able to state that I eat
the labors of my robots! Also along the way, design these
robots are do other interesting things such as compete in
the Trinity fire fighting contest. However my efforts have
been slowed a bit by a I/O board design that proved to have
a great deal of noise on it and cross talk on the serial
Then to soothe my great disappointment (it was a heck of a
lot of work!) I bought a little toy walking robot bug. My
thoughts were ``this looks like a nice quick weekend
project!''. How wrong I was.
The toy bot in question was the model I.B.34 Insecto-Bot. A
little fellow so ugly it has to be cute. I mistakenly
assumed this toy would use two motors on cams to move the
legs and thus allow a fairly simple brain transplant to more
intelligently control them. Unfortunately it turned out to
only have one motor. True to classic cheap toys (it after
all, only cost $15) it used a blizzard of gears and a
cleaver set of gears that engaged when the motor reversed.
Thus it could walk forward quite well and very badly turn
left only. Thus to make the little guy move I bought three
$20 mini servo motors.
I now have new respect of Dremel style motor tools! I've
done a tremendous amount of surgery on the little beast, and
I must say its coming out very nicely. Two big problems
were of course coming up with motor mounts and connecting
rods and cranks to the legs. The second big problem, the
The most evident of the modifications, the original battery
compartment only had 3 AAA batteries. For my application I
needed to have two independent batteries. This is due to a
walking robot having to do a lot more movement with the
motors. That uses a lot more draw current, and generates
more noise. A wheeled bot, with careful design can get along
just fine with one battery pack. Also I needed four batters
for each pack because the rechargeables have a lower
voltage. Thus the need to stuff EIGHT batteries where only
three had lived before! Lots of careful mototool work and
cleaver hinge design latter, they fit. Though he now has a
bit of a beer belly.
Next I have yet to build is the PC boards to control the
little guy. One thing I decided early on was I wanted him
to do something more interesting than the usual run around
and avoid bumping into things. I found a little recording
module at Radio Shack. It can record up to 20 seconds. The
thought is to have the bot walk up to something and attempt
to circumnavigate it. Then conclude the shape of it, and
vocally announce it. I'll give it a simple vocabulary of
words and have the processor start the play back and blank
the audio for only the words needed. This will make for a
stilted speech, but should be useful.
The sound module itself didn't produce enough volume to be
heard well but very close up. I happened to have a little 1
watt amplifier kit I had never assembled. It works well
with the output from the recorder. And as luck would have
it the little speaker in the toy robot (he originally made
random sounds)is just the right eight ohms the amp needed.
Now the little bot can down right shout!
I hope to have the electronics done in the next few weeks,
in-between the usual work on the other robots. Presently my
CNC is cutting out a sensor array board for the more complex
The sensor array board idea uses IR and ultra sonic. The
ultra sonic section is a Devantech SRF04. Latter designs I
hope to build my own ultra sonic hardware directly into the
board. The IR section is the new idea. It uses 4 IR
sensors and 3 IR LED's Using hardware PWM to adjust the
brightness of the LED's. The twin IR sets are pointed 45
degrees from the board, producing a large field of view.
The upper IR's are sensitive at 38khz and the lower set at
56.9Khz. One IR LED is centered between the IR sensor sets
with the other IR LED's flanking either side of the IR
sensors. With this setup it is possible to see seven
possible angle hits. Along with the crude changing of light
level I hope to use in software, a system where the number
of pulses returned verses transmitted is also used to give a
ruff calculation of distance. I realize it will be very
crud and heavily influenced by the color of objects but
should still be useful. If the idea works I'll use a
simpler one frequency, IR only setup for the walker.
I hope all of this isn't interpreted a crowing. I like to
hear and hope to hear more about what others are doing, and
hope my writing is also interesting.