Thread Subject:

Fuzzy Logic Toolbox Rules

I'm trying to use the fuzzy logic toolbox and my fuzzy system has 24 inputs.

I'm running into a bit of confusion when it comes to me creating the rules list now for the addrule function. My rules are actually quite simple. I have two specific cases, and one else case. However, it appears to me that there is no way to write the else case?

This becomes a bit daunting in that for 24 inputs, I'm going to have to write out every single combination of membership functions for these 24 inputs. Which is a huge, huge number. (i.e. Millions of lines of rules)

Surely there is a more sane way to implement the rules list in the fuzzy logic toolbox? Can any one point me in the right direction for this? I tried looking at the parsrule function, but I can only seem to get it to add one rule. Any subsequent rule I add seems to overwrite the first one? But even then, would this give me the ability to have a generic single line else type of rule? (Would A or B or C or D, etc work?)

Any thoughts are greatly appreciated...

Hi Ashley,
It seems like you should be able to define your rules with addrule function. Do you really have millions of rules for your 24 input variables? Can't you write a script that will generate the rule matrix for you if you have just a few rules as you say?

Also, you should be able to describe the "else" rule, using "not" operation.

For example, for a simple case with 2 inputs and 1 output, where each input has 3 membership functions, and output has 2 MFs let's say the rules are:
if (input 1 is MF1) and (input 2 is MF1) then (output is MF1),
else (Output is MF2).

else rule means:
if (input 1 is not MF1) or (input 2 is not MF2) then (output is MF2)

You can do that with this matrix:
[ 1 1 1 1 1;
-1 -1 2 1 2];

HTH.
Arkadiy




"Ashley Ee" <ee.ashley@gmail.com> wrote in message <hf794j$dfl$1@fred.mathworks.com>...
> I'm trying to use the fuzzy logic toolbox and my fuzzy system has 24 inputs.
>
> I'm running into a bit of confusion when it comes to me creating the rules list now for the addrule function. My rules are actually quite simple. I have two specific cases, and one else case. However, it appears to me that there is no way to write the else case?
>
> This becomes a bit daunting in that for 24 inputs, I'm going to have to write out every single combination of membership functions for these 24 inputs. Which is a huge, huge number. (i.e. Millions of lines of rules)
>
> Surely there is a more sane way to implement the rules list in the fuzzy logic toolbox? Can any one point me in the right direction for this? I tried looking at the parsrule function, but I can only seem to get it to add one rule. Any subsequent rule I add seems to overwrite the first one? But even then, would this give me the ability to have a generic single line else type of rule? (Would A or B or C or D, etc work?)
>
> Any thoughts are greatly appreciated...