Re: Consistency of fuzzy rules

From: Yaochu Jin (ftrjin@mail.ipm.net)
Date: Tue Oct 30 2001 - 09:48:53 MET

  • Next message: Martin Lefley: "Inconsistency of fuzzy rules"

    >How about these two rules:
    >
    >R1: IF obstacle is straight ahead THEN turn left
    >R2: IF obstacle is straight ahead THEN turn right
    >

    A nice counter-example. To deal with this problem, an ad-hoc defuzzification
    method has to be (and has been) developed to resolve this contradiction.
    Otherwise, a robot will hit the very obstacle using these two fuzzy rules.
    Instead developing an ad-hoc defuzzification method to resolve the
    contradiction, I would prefer remove one of the rules or revise the rules as
    follows:

    R1: IF obstacle is straight ahead AND there is no obstacle on the right,
        THEN turn right;

    R2: IF obstacle is straight ahead AND there is no obstacle on the left,
        THEN turn left;

    What happens if there are obstacles both on right and left? Make a U-turn :-)
    As a matter of fact, the following problem is still open in robot navigation as
    far as I know ( that is, the target is behind of a long flank obstacle:)

                            X (target)
                            
         ============================================== (Obstacle)
      
                                 OO (Robot)
                            
    Sincerely
    Yaochu Jin

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