Elma Beaucoups by Dave Benz

Tons of pictures, circuit schematics, history & info at:
http://members.aol.com/benzsaw

Current Specs & Info:
   An "art robot", Elma Beaucoups was designed to be an autonomous phototaxic 
robot arm. For portability, I wanted all necessary electonics to be mounted 
on the arm (instead of tethering the thing to a PC.)

   Elma's brain is a Basic Stamp 2 (BS2.) Elma is also equipped with a dual 
H-Bridge to drive the motors, and an IR remote system which operates using 
Dial Tone Multi-Frequency tones to transfer information. Elma talks to the 
world via beeps through a simple amplifier circuit & speaker. To increase the 
number of I/O pins available, Elma is equipped with a parallel-in serial-out 
8 bit shift register.

   The flower mounted on the light sensor array is a piece of origami. 
Without it Elma looks kind of strange. 

   One gear head DC motor drives the shoulder via a drive chain system, which 
provides further reduction. The elbow is driven with a DC motor using a worm 
gear drive train scavenged from a defunct VCR.

   Elma Beaucoups can operate autonomously using photoresistors to display 
phototaxic behaviors. The robot has two degrees of freedom. An optical shaft 
encoder is used to determine shoulder position and a bend sensor provides 
elbow position. Since both encoders are absolute, no limiting switches have 
been installed.

   The IR remote cato drive the elbow & shoulder continuously via remote 
control.

   Since it was my first robot I guess I had to do everything the hard way. 
Elma was built from scratch. A lot of people talk about not wanting to 
redesign the wheel, and while I can see the rationale, I wanted to really 
learn the nuts and bolts of robotics. Looking back on it, life would have 
been a lot easier using servos, and sometimes I regret not using them. At the 
same time, though, shaft encoders are really neato.

   Elma is tethered to a 9 volt AC to DC converter. Some of the electronics 
and the motors run at 9 volts. Everything else runs at 5 volts, which is 
supplied by the BS2.

The Name:
   Elma Beaucoups is a flower at heart, and a machine in body. The name came 
after I spent 2 months calling Elma "the elbow" which turned to "EL BO" and 
later, after being jokingly prodded by most of my friends about how it was my 
new girlfriend (and was going to keep me warm at night,) the name changed a 
lot. A few examples: "Eliza Bonita," "Ellie Bowler." The name that stuck was 
finally "Elma Beaucoups," which translates from French to "Lots and lots of 
Elma."
   Oui! Oui! Oui!

Major Problems Encountered:

   Connections seem to be the woe of all roboticists, and my experience was 
no different. After suffering bug after bug after bug, I finally had to 
resort to crimping and carefully soldering all my wire-to-connector joints.

   As of this writing, my other biggest problem is sensor oversensitivity 
combined with motor overshoot, which has forced me to use rather low 
resolution on the encoders and strange oversampling and overcompensation 
routines in my software. I'm still working on using PWM & velocity control to 
slow Elma down gracefully when approaching the end of a movement.

   Time to build: So far around 3 months, working whenever I get a chance.

   Cost: Not counting man-hours, probably around $300 for everything 
currently installed. Tool purchases and R&D costs are probably significantly 
higher than that.

   Other important information: If you have ever dreamed of creating a robot 
I would very stongly encourage you to start today. It is a great learning 
experience, and a lot of fun. While it is really cool and challenging to 
build something you can direct via remote control, it's pretty wacky to see 
something you built make decisions and move on its own. Even though I had a 
vision of what it would be like, when Elma finally became autonomous it 
really freaked me out somehow.

   It's like being Dr. Frankenstein. Oh! And your friends will enjoy playing 
with it.

   Future Directions: Besides tiny system upgrades and improvements, I am 
considering motion detection and other sensor arrays for Elma Beaucoups. I 
also have ideas for two other robots now.
 
    Please find attached a photo of my robot to go with my Robot Menu 
submission. Thank you for providing this wonderful service.

    If I need to submit using the form, please inform me & I will try from my 
work account.


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