# fuzzy logic, Gatherings

**URL:** http://discourse.iapct.org/t/fuzzy-logic-gatherings/13860
**Category:** CSG1992
**Created:** [March 4, 1992, 6:51pm UTC](http://discourse.iapct.org/t/fuzzy-logic-gatherings/13860 "1992-03-04T18:51:36Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![marken\_aero.org](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/m/67e7ee/32.png) [@marken\_aero.org](http://discourse.iapct.org/u/marken_aero.org)
#### Post date: [March 4, 1992, 6:51pm UTC](http://discourse.iapct.org/t/fuzzy-logic-gatherings/13860/1 "1992-03-04T18:51:36Z")

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[From Rick Marken (920304)]

Bruce Nevin (Wed 92014 10:35:52) says:

> To point this up, the box on p. 38 of the article describes Takeshi  
> Yamakawa's fuzzy controller and its solution of the "inverted pendulum  
> control problem."

> Can we show how HPCT maintains the virtual equivalents of fuzzy sets and  
> does the equivalent of fuzzy inference for this sort of control?

I think the best comment on this fuzzy control stuff was made about a  
year ago when the fuzzy "inverted pendulum controller" was posted to  
csgnet. This program was huge (in source) -- many megabytes. Bill  
Powers (in a matter of hours) posted an inverted pendulum controller  
based on good old fashioned control theory. It was maybe twenty lines  
of code, most of which handled the physics. My opinion -- fuzzy logic  
is a solution looking for a problem. The problems that it has been  
applied to already have better solutions. But fuzzy logic is trendy  
science -- so that's where the bucks go.

I think you are right -- people seem to want to deal with the world at  
the principle level or higher. I see this here at Aerospace where there  
is an unbelievable reverence for "expert systems" -- and this is  
coming from engineers, many of whom have been trained in control theory.  
I think they are so used to dealing with control problems verbally -- like  
"That voltage there is decreasing TOO QUICKLY. We better switch to SIDE B"--  
that they don't notice that they are just controlling quantitative variables  
(keep the rate of dischage = x). It's a very interesting phenomenon, this  
regression to symbol manipulation by quantitatively trained people. I  
think it speaks to how deeply imbued we all are with stimulus-response  
preconceptions about behavior.

To Bill Powers: You may have done this before but I would appreciate it  
if you could post a simple diagram of the "persons" in the Gatherings  
program. I want to write a program that demonstrates (on an individual  
basis) some of the points you make with the gatherings program -- i.e.  
behaviors like "circles of people" and "backtracking" are just observed  
side effects of each person's efforts to control peceptions like  
proximity, speed, etc. So what are the controlled variables in the  
Gatherings program and how are they related? I think I remember  
that one was "proximity" and the other is "speed" -- is that right?  
Are they controlled independently? Thanks for the info.

Regards

Rick

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> Richard S. Marken USMail: 10459 Holman Ave  
> The Aerospace Corporation Los Angeles, CA 90024  
> Internet:marken@aerospace.aero.org  
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