Alt-BEAM Archive
Message #05503
To: beam@sgiblab.sgi.com
From: Bruce Robinson Bruce_Robinson@bc.sympatico.ca
Date: Sat, 31 Jul 1999 13:44:09 -0700
Subject: [alt-beam] Re: BEAM and CPU's
Ian Bernstein wrote:
>
> ... It also seems that as soon as you want to add multiple sensors and
> give the bot more gaits the circuit just grows dramatically and becomes
> very complex.
True ... but you might be able to simplify the complexity by looking at
human motor skills.
At the lowest level, we use the same motor neurons and feedback sensors
(proprioceptors) to control all our physical skills. When we learn new
skills, at first the brain tries to control all the muscles
individually. That's why people are often awkward and clumsy when
learning new tasks -- their brains get overloaded managing low-level
actions. But when a task is performed often enough (approximately 50
times or so), intermediate neurons are permanently programmed to
co-ordinate muscle groups (Central Pattern Generators). Then the brain
has only to send a few signals to the intermediate neurons, which in
turn take care of co-ordinating very skilled tasks.
Assuming we builders bypass the motor-learning process and just build
the intermediate circuits, there's a couple of routes we could take.
One BEAM equivalent would be to use a set of independent Nv networks to
perform individual tasks; connect neurons from the different nets to
individual motor inputs by using AND or NAND gates, and only operate one
Nv net at a time. You could, for example, use one Nv net for a simple
walking gait, a second for a running gait, and a third (on a complex
'bot) to walk backwards. This would be a very good method when you
wanted to change the sequence that various motors operated in.
A second BEAM equivalent would be to use completely different resistor
values on the Nv neurons. Each set would be connected to a common
terminal point via diodes. Setting a terminal point to ground would
activate the set of resistors attached to it. Setting the terminal point
to Vcc would inactivate the resistors. This would be a good method when
you wanted to use the same sequence to operate motors, but vary the
timing.
Both these methods add to the complexity and parts count. The big plus
is that they allow different functions to be individually fine-tuned.
This idea can be carried to a higher level. Say I have separate Nv nets
to walk forward, back up, turn quickly left, and run forward. Now I can
create a higher level Nv sequence that in turn triggers the "back up"
net, the "turn left" net, and the "run forward" net. So if my
hypothetical 'bot senses a dangerous situation, it can activate the
higher level loop that will cause it to back away, turn, and run in the
direction it came from.
Sounds good in theory -- will it work? I dunno. I'm going to find out,
but probably not before Christmas. Wouldn't it be easier to program a
CPU? Probably. Would making a CPU 'bot be as much fun? Nope, not for me
.
> I'm up to the challenge and just wanted to see what you guys thought
> before I start. Also how many motors should I use, 4?
Go for three -- two for the legs, one for the waist. Then we can compare
results .
Regards,
Bruce
5504 Sat, 31 Jul 1999 14:15:56 -0700 (PDT) [alt-beam] Re: Fwd: Symets, Web page and BEAM vs. Computers beam@sgiblab.sgi.com "Travis D." but in the case of BEAM, the 'programming' is
basically the layout of the electronics. change the
layout, get different behaviors. Granted, you can't
make the complex occurances of computers, but take
into account the shere #'s of components in computers.
Currently, BEAM robots are simplistic, but who knows
what the future holds...some day, complex behaviors
(life-like) may require computer-like layouts....
just some food for thought
--- Ian Bernstein wrote:
>
> ---------------- Begin Forwarded Message
> ----------------
> Date: 07/31 9:23 AM
> Received: 07/31 9:59 AM
> From: Noam Rudnick, rudnick1@cwix.com
> To: synet@beam-online.com
>
> Hi,
> > BEAM vs. The computer----
> > I was just giving this some thought and I just
> wanted to see what you
> > guys thought.... BEAM stuff is.... What? Any robot
> that doesn't use a
> > cpu? A robot that fits into the "BEAM"? It seems
> only bots that use
> > Tilden's circuits are 'BEAM' robots????? I mean if
> I came up with a
> > really cool circuit and bot nobody here would call
> it a 'BEAM' robot?
> > Why? Am I wrong here? And.... BEAM robots are made
> of transistors. Cpu's
> > are made up of transistors. Whats the difference?
> Other than that a cpu
> > could be called just a really complex 'BEAM'
> circuit that has memory and
> > you can 'program' it.
>
> I like to think that there is an important
> difference between beam and
> traditional cpu based robots. CPUs carry out a
> predetermined program over
> and over again, and operate in a very unnatural way.
> They go through a
> routine which can easily be mapped out in the form
> of a flowchart. BEAM
> robots on the other hand rely on idependant, yet
> closely related
> reflexes.
> Although the end effect might turn out to be quite
> similar, the scond
> method will tend to be less complex, faster, yet
> much more complicated to
> reprogram. From my knowledge, the second method
> also appears to mimic
> biology much more closely. We also must ask
> ourselves if we really care
> *how* robots think as long as the output is the
> same.
>
> Just my opinions,
> Noam Rudnick
>
> P.S. Since for some reason I am unable to send mail
> to the list, I would
> appreciate it if you could forward it. Also please
> make a note that all
> responses should be CCed to my personal account as
> well as the list.
>
> Thanks
>
> ----------------- End Forwarded Message
> -----------------
>
>
>
*-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-*
> Ian Bernstein "aka - Synet" The
> Master Builder
>
> E-Mail - Ian@beam-online.com
> BEAM Online - http://www.beam-online.com
> Quote - "Programming today is a race between
> software engineers
> striving to build bigger and better idiot-proof
> programs, and the
> Universe trying to produce bigger and better idiots.
> So far, the Universe
> is winning."
> - Rich Cook
>
>
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