# Re: Fuzzy Login and Traffic Light

From: Fractal A. (fractala@yahoo.com)
Date: Wed Oct 10 2001 - 23:49:43 MET DST

• Next message: masoud nikravesh: "BISC: Lotfi A. Zadeh"

Hi,

This is a diagram of an intersection with arrows in 4 lanes to show the
direction that the traffic flows in the lanes. There is a conventional
numbering from 1 to 8 for this that I do not recall, so I used letters to label
the lanes. I hope that you can read the diagram and that the mailer doesn't
skew it.

| | |
| | |
| |/|\|
| | |
| A | B |
------------ ------------
<---H C
- - - - - - - - - - - -
G D--->
------------ ------------
| F | E |
| | |
|\|/| |
| | |
| | |

So, if AB FE have low speed & low density, you want the light to stay green?
What if CD GH have high density & high speed and AB FE have low density & low
speed? Would you still want AB FE to stay green?

You use a basic membership diagram--fit your curve of motion to it. Assign
values according to what you want to happen at different speeds and densities.
You may want to try a trapezoidal or triangular function. The triangular one
is easier than the trapezoidal one. When you are at the top of the triangle,
the light is always green is one way to do it. The other way might be to flip
the values so that 1 is at the base of the triangle and 0 is at the tip of the
triangle. Sorry if this makes no sense. I hope that it helps you some. There
are a bunch of sources out there about membership diagrams and defuzzification
and such. I usually read them before I try and do anything with it. A simple
google search for fuzzy & defuzzification & fuzzy membership & things like that
will get you headed in the right direction.

Peace & Good Wishes on your Project!

Fractal A.

--- afshin akbari <afshin.akbari@sympatico.ca> wrote:
> All,
>
> I am trying to simulate an intersection using matlab.
>
> We are trying to graph a green light duration as the result of
> speed and density. One of the outputs is given to be Green Light
> "Constant ON".
>
> My question is, how do we define or assign a numerical value for > constant
on?
>
> if speed is slow and density is low then Green Light is constant ON
>
> any hint is greatly appreciated.
>
> aa-

=====
Fractal A. fractala@yahoo.com

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