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|Target Environment||Locomotion Method|
|Sensors / Input Devices||Actuators / Output Devices|
optical shaft encoders
two DC motors
|Control Method||Power Source|
|Autonomous||AC to DC converter via a tether|
|CPU Type||Operating System|
|Time to build||Cost to build|
|around 3 months||around $300|
|URL for more information|
|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.