Data processing: artificial intelligence – Fuzzy logic hardware
Patent
1996-08-09
1998-08-25
Davis, George B.
Data processing: artificial intelligence
Fuzzy logic hardware
706 5, 706900, G06F 944
Patent
active
057992916
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
On the basis of the respective specific circumstances of the control problem which is to be solved, the linguistic protocol of a fuzzy controller will generally contain rules of differing importance. This circumstance can be taken into account, for example, by each rule being provided with a scaling factor for the importance of the respective rule. This superficial solution, however, has the serious disadvantage that a corresponding arrangement requires a great deal of memory space and is thus in practice unsuited for fuzzy controller hardware with on-chip memory.
The German journal atp-Automatisierungstechnische Praxis 34 (1992), 4, pages 176 to 184, and 5, pages 239 to 246, discloses a fuzzy controller in which individual conditions in the IF part of a respective rule are linked by means of unsharp AND links in the form of a minimum linking to form an overall condition, and output values from the THEN parts of rules are linked by means of unsharp OR links in the form of a maximum linking to form an overall consequence.
German Offenlegungsschrift DE 42 25 758 A1 discloses the possibility that rule groups having important and less important rules can be formed and that the important rules can be unsharply OR linked by means of a limited sum formation and the less important rules can be unsharply OR linked by means of a maximum formation.
SUMMARY OF THE INVENTION
The object on which the invention is based is, then, to specify an arrangement in which it is ensured that at least each important (dominant) rule, whose conditional part (IF part) is satisfied, has an influence on the sharp value of the respective output variable and cannot be completely "masked out" by less important rules having possibly higher membership function values, as is the case in known fuzzy controllers, and in which particularly little memory space and control outlay is necessary.
In general terms the present invention is an arrangement for separate processing of fuzzy rules of differing importance. In a knowledge base memory, important and less important rules are stored such that they can be distinguished from one another. From a rule weighting of a respective rule and from an aggregated rule weighting of previous rules, using a unit for forming an unsharp OR link, a new aggregated rule weighting is formed. The unit for forming an unsharp OR link is a unit for forming a limited sum, if an important rule is present, and is a unit for forming a maximum, if a less important rule is present. A one input of a multiplexer is connected to the output of the unit for forming the limited sum and a zero input of the multiplexer is connected to the output of the unit for forming a maximum. A controller is provided such that, in the knowledge base memory, all the important rules in one block are addressed chronologically after the less important rules. A load input of a reverse counter is fed the number, stored in the knowledge base memory, of the important rules. The controller, after the processing of a respective rule, supplies a signal to a counting input of the reverse counter until all the important rules have been processed. The output signal of the reverse counter is OR linked bit by bit and serves as a control signal for the multiplexer. There is in each case at one input of both units the respective rule weighting and there is in each case at a further input of both units the previous aggregated rule weighting.
The advantage of the invention is in particular that, above all in the case of fuzzy controllers which are flexible in use, there results only a very slight additional cost in terms of circuitry, since in this case, in order to implement an unsharp OR link, in addition to a unit for maximum forming, provision is in any case made of at least one further unit such as, for example, a unit for forming a limited sum.
BRIEF DESCRIPTION OF THE DRAWING
The features of the present invention which are believed to be novel, are set forth with particularity in the appended claims. The invention, together w
REFERENCES:
patent: 4985824 (1991-01-01), Husseiny et al.
patent: 5031224 (1991-07-01), Mengel et al.
patent: 5077677 (1991-12-01), Murphy et al.
patent: 5109522 (1992-04-01), Lent et al.
patent: 5321491 (1994-06-01), Summers et al.
patent: 5371832 (1994-12-01), Eichfeld et al.
patent: 5546506 (1996-08-01), Araki et al.
patent: 5600757 (1997-02-01), Yamamoto et al.
Automatisierungstechnische Praxis 34 (1992) 4, Fuzzy Control--Heuristic control by means of fuzzy logic, Hans-Peter Preuss, pp. 176-184.
Automatisierungstechnische Praxis 34 (1992) 5, Fuzzy Control--Heuristic control by means of fuzzy logic, Hans-Peter Preuss, pp. 239-246.
Eichfeld Herbert
Kunemund Thomas
Davis George B.
Siemens Aktiengesellschaft
LandOfFree
Arrangement for the separate processing of fuzzy rules of differ does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Arrangement for the separate processing of fuzzy rules of differ, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Arrangement for the separate processing of fuzzy rules of differ will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-46696