From: rshepard@salmo.appl-ecosys.com   
      
   On 2004-04-14, Luko  wrote:   
      
   > my question is very simple:   
   > where and why not use fuzzy?   
      
   Luca,   
      
     Your question looks 'very simple' to you -- because you know exactly what   
   you mean. However, when you look at the range of answers it is clear that   
   words mean different things to different people. The very first response was   
   based on one person's interpretation of what you meant, and off went the   
   discussion into Bill Siler's fur-lined chamber pot.   
      
     This thread is a perfect illustration of when fuzzy logic is appropriate.   
   Any time you have inherent imprecision or required a graduated degree of   
   response to changing situations fuzzy system models are appropriate.   
      
     Disclaimer: I am NOT an engineer, I work with the natural world, not the   
   human-built world. So, I do not design controllers. However, I suspect that   
   if image stabilization systems and automatic train systems could have been   
   built without fuzzy logic controllers we would have seen them on the market   
   many years earlier.   
      
     But, let me try to provide some food for thought. Consider your computer.   
   It is either on or off (unless you run Microsoft in which case there's no   
   telling in what state it might be). This is not an application for a fuzzy   
   logic controller. The power is either full on or full off.   
      
     On the other hand, consider the temperature thermostat in your house. You   
   set the desired temperature for 20C. How far below 20C should the   
   temperature fall before your controller turns on the furnace? Does the   
   furnace run full-blast immediately? How much higher than 20C should the   
   temperature be before you turn off the furnace? You can design an embedded   
   controller with fixed thresholds, but you'll need a lot of them to keep both   
   men and women comfortable in your house.   
      
     With a fuzzy logic system in your thermostat it can respond to rules such   
   as:   
   	IF the temperature is slightly below 20C   
   		THEN turn on furnace part way and increase fan speed.   
      
   You can make up the rest of the rules.   
      
     I agree with Earl and Bill that this is another silly question. If you've   
   read all the books and still don't understand what you've read, then you're   
   playing in the wrong sandbox. Get an Etch-A-Sketch(R) as a portable computer   
   and seek another subject to learn.   
      
   Rich   
      
   --   
   Dr. Richard B. Shepard, President   
   Applied Ecosystem Services, Inc. (TM)   
      
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)