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ediebur@rcn.com
science forum beginner
Joined: 06 Jul 2006
Posts: 1
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 Posted: Thu Jul 06, 2006 11:43 am Post subject:
What happened to fuzzy set theory
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Fuzzy set theory was quite popular in the sense that it captured the
popular imagination. I think Japan even built a microprocessor based on
it. What happened? |
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C6L1V@shaw.ca
science forum Guru
Joined: 23 May 2005
Posts: 628
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| Posted: Thu Jul 06, 2006 2:21 pm Post subject:
Re: What happened to fuzzy set theory
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ediebur@rcn.com wrote:
| Quote: | Fuzzy set theory was quite popular in the sense that it captured the
popular imagination. I think Japan even built a microprocessor based on
it. What happened?
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It exploded, It is applied in many areas such as camera focussing,
controllers of all types, etc. Just do a simple Google search to see
the vast variety of applications that have been suggested or
implemented already. Having said that, I must admit that I am still a
skeptic. At a conference, I once discussed with a control systems
expert the reason why fuzzy controllers are used and sometimes have
performance that exceeds that of ordinary controllers. His claim (and I
have no independent verification of this) is that fuzzy controllers
tend to monitor the system very closely---more closely that typical
classical controllers---and so use better estimates of the "state".
Their use of better information results in better performance, or so he
said.
R.G. Vickson |
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Proginoskes
science forum Guru
Joined: 29 Apr 2005
Posts: 2593
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| Posted: Thu Jul 06, 2006 10:36 pm Post subject:
Re: What happened to fuzzy set theory
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C6L1V@shaw.ca wrote:
| Quote: | ediebur@rcn.com wrote:
Fuzzy set theory was quite popular in the sense that it captured the
popular imagination. I think Japan even built a microprocessor based on
it. What happened?
It exploded, It is applied in many areas such as camera focussing,
controllers of all types, etc. Just do a simple Google search to see
the vast variety of applications that have been suggested or
implemented already. Having said that, I must admit that I am still a
skeptic. At a conference, I once discussed with a control systems
expert the reason why fuzzy controllers are used and sometimes have
performance that exceeds that of ordinary controllers. His claim (and I
have no independent verification of this) is that fuzzy controllers
tend to monitor the system very closely---more closely that typical
classical controllers---and so use better estimates of the "state".
Their use of better information results in better performance, or so he
said.
|
The only problem is that, in order to get something that works in the
physical realm, you need to assign specific values to some fuzzy
concepts. (A concept called "defuzzification".)
Fuzzy logic may be the best way to find these values, but in the end,
we're back at deterministic algorithms.
--- Christopher Heckman |
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Han de Bruijn
science forum Guru
Joined: 18 May 2005
Posts: 1285
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| Posted: Fri Jul 07, 2006 7:17 am Post subject:
Re: What happened to fuzzy set theory
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Proginoskes wrote:
| Quote: | The only problem is that, in order to get something that works in the
physical realm, you need to assign specific values to some fuzzy
concepts. (A concept called "defuzzification".)
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So what?
| Quote: | Fuzzy logic may be the best way to find these values, but in the end,
we're back at deterministic algorithms.
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Fuzzy logic _is_ deterministic. The difference with common logic is that
its values are not restricted to 0 xor 1 but assume anything in between:
http://en.wikipedia.org/wiki/Fuzzy_set
Han de Bruijn |
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user
science forum beginner
Joined: 07 Jul 2006
Posts: 1
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| Posted: Fri Jul 07, 2006 2:38 pm Post subject:
Re: What happened to fuzzy set theory
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If somebody is interested in the relation between fuzzy sets theory and
fuzzy sets then that is a good source of information:
http://andrzej.pownuk.com/fuzzy.htm
ediebur@rcn.com napisal(a):
| Quote: | Fuzzy set theory was quite popular in the sense that it captured the
popular imagination. I think Japan even built a microprocessor based on
it. What happened? |
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user
science forum beginner
Joined: 07 Jul 2006
Posts: 1
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| Posted: Fri Jul 07, 2006 2:43 pm Post subject:
Re: What happened to fuzzy set theory
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Of course I should write "fuzzy sets" and "probability".
Sorry for the mistake.
user napisal(a):
| Quote: | If somebody is interested in the relation between fuzzy sets theory and
fuzzy sets then that is a good source of information:
http://andrzej.pownuk.com/fuzzy.htm
ediebur@rcn.com napisal(a):
Fuzzy set theory was quite popular in the sense that it captured the
popular imagination. I think Japan even built a microprocessor based on
it. What happened? |
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Toni Lassila
science forum Guru Wannabe
Joined: 04 May 2005
Posts: 135
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| Posted: Fri Jul 07, 2006 3:44 pm Post subject:
Re: What happened to fuzzy set theory
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On 6 Jul 2006 15:36:27 -0700, "Proginoskes" <CCHeckman@gmail.com>
wrote:
| Quote: | C6L1V@shaw.ca wrote:
ediebur@rcn.com wrote:
Fuzzy set theory was quite popular in the sense that it captured the
popular imagination. I think Japan even built a microprocessor based on
it. What happened?
It exploded, It is applied in many areas such as camera focussing,
controllers of all types, etc. Just do a simple Google search to see
the vast variety of applications that have been suggested or
implemented already. Having said that, I must admit that I am still a
skeptic. At a conference, I once discussed with a control systems
expert the reason why fuzzy controllers are used and sometimes have
performance that exceeds that of ordinary controllers. His claim (and I
have no independent verification of this) is that fuzzy controllers
tend to monitor the system very closely---more closely that typical
classical controllers---and so use better estimates of the "state".
Their use of better information results in better performance, or so he
said.
The only problem is that, in order to get something that works in the
physical realm, you need to assign specific values to some fuzzy
concepts. (A concept called "defuzzification".)
|
Where is the problem? If you design a fuzzy PI controller for a crisp
system then the end result will be equivalent to a conventional PI
controller. It is when the model is imprecise, overly complicated, or
non-existant when the fuzzy controllers stand out from the rest.
I'm not sure that fuzzy controllers beat conventional controllers in
comparison because they "monitor the system very closely", but rather
because they're often compared to linear controllers only. Since the
fuzzy controller is non-linear, it is not surprising that it can in
many cases give better results.
| Quote: | Fuzzy logic may be the best way to find these values, but in the end,
we're back at deterministic algorithms.
|
As mentioned, fuzzy controllers are deterministic. But it seems the
field is somewhat ripe with extraordinary claims as to what model-free
controllers can accomplish. I'd certainly take some things with a
grain of salt. Sort of like with genetic algorithms. |
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Proginoskes
science forum Guru
Joined: 29 Apr 2005
Posts: 2593
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| Posted: Fri Jul 07, 2006 11:20 pm Post subject:
Re: What happened to fuzzy set theory
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Proginoskes wrote:
| Quote: | C6L1V@shaw.ca wrote:
ediebur@rcn.com wrote:
Fuzzy set theory was quite popular in the sense that it captured the
popular imagination. I think Japan even built a microprocessor based on
it. What happened?
It exploded, It is applied in many areas such as camera focussing,
controllers of all types, etc. Just do a simple Google search to see
the vast variety of applications that have been suggested or
implemented already. Having said that, I must admit that I am still a
skeptic. At a conference, I once discussed with a control systems
expert the reason why fuzzy controllers are used and sometimes have
performance that exceeds that of ordinary controllers. His claim (and I
have no independent verification of this) is that fuzzy controllers
tend to monitor the system very closely---more closely that typical
classical controllers---and so use better estimates of the "state".
Their use of better information results in better performance, or so he
said.
The only problem is that, in order to get something that works in the
physical realm, you need to assign specific values to some fuzzy
concepts. (A concept called "defuzzification".)
Fuzzy logic may be the best way to find these values, but in the end,
we're back at deterministic algorithms.
|
As a couple of posters have pointed out, "deterministic" is the wrong
word above. I should have said something like "traditional logic"
instead.
Also, the above represent opinions formed only from reading Bart
Kosko's _Fuzzy Thinking_. He didn't seem to really "sell" me on the
idea of fuzzy logic in that book.
--- Christopher Heckman |
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