Alt-BEAM Archive
Message #03876
To: beam@sgiblab.sgi.com
From: Jean auBois aubois@trail.com
Date: Fri, 28 May 1999 11:38:50 -0600
Subject: [alt-beam] Re: Unicore (was: PBS special- Poppers)
At 07:22 PM 5/27/99 , Jason - wrote:
>>Hi. I believe you are talking about the beamant 6.6 it is driven by
Mark's unicore design. He isn't releasing any details yet
He 'released' handouts about the unicore design at the Telluride
Neuromorphic Workshop a Long Time Ago. If the following description is
even close to being accurate, the technology is covered by Mark Tilden's
patent.
Look at the advanced Nv network portion of the BEAM Tek site, particularly
the "phototropic" stuff (geez -- do you know how LONG ago I wrote that
article??? It was the result of Mark explaining this beast to me.) It
describes the basic idea of using two IR sensors and two resistors as a
predictable differential light-sensitive element. Take that, add two of
the inverters from a '240 and a couple of capacitors and you've got the
visual bicore.
Embed that into another bicore which, for the sake of argument, you call
the central oscillator. This means that you need two coupling resistors
between the bicores, two more of the inverters from the '240 and a couple
more capacitors.
Use two more of the inverters from the '240 and add a resistor and
capacitor each to make two Nv neurons; connect their inputs to the outputs
of the central oscillator. Connect the outputs of these Nv neurons to one
end, each, of two motors.
Make a couple of 'tactile' sensors. Use the final two inverters of the
'240, two more resistors, and two more capacitors to make two Nu neurons.
Connect the tactile sensors to the inputs of the Nu neurons; connect the
outputs of the Nu neurons to the other ends, each, of the two motors.
Note: the '240 has to be able to source/sink enough current to run the motors.
You now have a unicore beamant, more-or-less. Note: you still have to
figure out the values of: 2 resistors in the light-sensitive bridge, visual
bicore capacitor values, coupling resistor values, central oscillator
capacitor values, Nv resistor and capacitor values, and Nu resistor and
capacitor values. You'll also have to figure out how to hook up the light
sensitive bridge to the visual bicore (i.e. which sensor affects which
phase), how to hook up the visual bicore to the central oscillator, how to
hook up the Nv neurons to the motors and likewise the Nu neurons. By "how
to hook up" I mean whether or not the connections are "straight" or
"crossed". Generally speaking, a wide range of behaviors can be achieved
by varying the resistor values and the hookup topology.
I don't have a clue how to deal with the power supply -- Dennison's got
something, doesn't he? Of course, you could always use a rechargeable coin
cell.
In normal operation, the two motors alternate continuously as long as there
is enough power (unlike a photopopper where one motor might get power
several times in a row.) The device obviously steers away from the side
where the motor stays on longest (in other words, although they alternate,
the duration of each side depends on the bicores.)
The Nv and Nu neurons form XOR drivers. When a tactile sensor is
activated, its corresponding Nu neuron triggers for some pre-determined
amount of time. When it is triggered, the 'meaning' of the Nv signal for
that motor is inverted which produces the "reverse" behavior.
Or something like that. This is probably a rather faulty description.
Your mileage may vary. Perhaps Rigter or Wouter or Chiu or Dennison or
someone can digest this and explain it better.
---------------------------------------------------------------
jab
Do you have a BEAM question? Try one of the following sites -- they really
help!
BEAM Robotics Tek FAQ http://people.ne.mediaone.net/bushbo/beam/FAQ.html
BEAM Mailing List Archive http://www.egroups.com/list/alt-beam/
BEAM Online http://www.beam-online.com/
Chiu-Yuan's BEAM Page http://www.geocities.com/SouthBeach/6897/
BEAM Heretics http://www.serve.com/heretics/
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