Alt-BEAM Archive

Message #04961



To: beam@sgiblab.sgi.com
From: "John A. deVries II" zozzles@lanl.gov
Date: Tue, 29 Jun 1999 15:14:11 -0600
Subject: [alt-beam] Re: Bicore Feedback Experiments


At 01:44 PM 6/29/99 , Ivar Thorson wrote:

>I think that seems to be an effective use of feedback, if you ask
>me. It gets a little stuck, and it shakes faster. It gets really
>stuck, and it thrashes violently with long strides until it is free.


Ok, fine for the suspended bicore case. However, the "implex is a good
thing for a robot" was stated long before the community began using bicores
on a regular basis & I'm pretty sure that suspended bicores are (as Wilf
originally stated) Really Different than the 'everyday' nervous net.
Remember, his original conclusions were that a suspended bicore are
somewhat unlikely to get started in the first place! Nonetheless, if the
leg is REALLY stuck, mightn't the thrashing cause the robot to shake itself
to pieces??? If I were to overextend the metaphor, it reminds me of the
hunter finding nothing left in his trap but the animal's leg...

When considering the case where the outputs are buffered, I've got to ask
the question I asked before: are you using the same chip for the bicore &
the buffering inverters? Methinks that if you used something like:

>Doing similar experiments with H-Bridges for motor drivers would be
>nice, too. How much feedback to different designs provide, does a
>feedback resistor help, etc.

particularly when you use a -separate- power supply for the buffer/driver
that you'd see different results. I also have to ask another question:
did you read Wilf's report on his experiment with regard to the feedback
resistor?

In any case, a suspended bicore simply isn't the same animal as a six Nv
neuron loop, so the conclusions about the results/value of implex for one
needn't (and probably don't) apply to the other. BTW: I've stuck a very
early note from Mark to his boss about the "feedback" phenomenon under
"Golden Oldies" in the Tilden section on the Heretics site. It is a very
interesting item -- I'd like to read someone's (anyone's? Wouter?)
discussion about how high-inertia rotors make a difference.


Ah well, only experimentation will tell.

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