Fuzzy inference device

• US 5,280,566 A
• Filed: 03/13/1991
• Issued: 01/18/1994
• Est. Priority Date: 03/15/1990
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Nakamura, Kazuo
• Primary Examiner(s): MacDonald, Allen R.
• Application Number:
  US07/669,131
• Time in Patent Office: 1,042 Days
• Field of Search: 395/3, 395/61, 395/900, 395/51
• US Class Current: 706/52
• CPC Class Codes: G06N 5/048 Fuzzy inferencing
• CPC Class Codes: G06N 7/026 Development tools for entering the parameters of a fuzzy system
• CPC Class Codes: Y10S 706/90 Fuzzy logic

Abstract

A fuzzy inference method which improves reliability of an inference result by obtaining a variance which is a statistical value. The variance considers not only the value of a membership function derived from performing maximum operation (logical AND) but also a position of the function. These values are added and, according to this result, any inconsistency in fuzzy rules is detected.

Claims

1. Apparatus for performing fuzzy inference, comprising:

means for processing an antecedent to obtain a plurality of first membership functions forming a consequent in accordance with a plurality of fuzzy rules;

means for processing said consequent to obtain a second membership function by selecting a greater one of each of said plurality of first membership functions obtained by the processing of said antecedent;

means for supplying an output in accordance with said second membership function;

means for obtaining a variance in accordance with the second membership function; and

means for evaluating a reliability of said output in accordance with said variance.

2. The apparatus for performing fuzzy inference of claim 1 wherein said means for obtaining a variance comprises means for calculating a quadratic variance.

3. The apparatus for performing fuzzy inference of claim 1 wherein said means for obtaining a variance comprises means for selectively adding and subtracting product terms including means for (i) multiplying a series of consequent values by respective corresponding values of said second membership function to supply said product terms, and (ii) selectively adding and subtracting said product terms to supply said sum of products.

4. An apparatus for performing fuzzy inference, comprising:

means for processing a value of an antecedent to obtain a plurality of first membership functions forming a consequent in accordance with a plurality of fuzzy rules;

combining means for processing said consequent to obtain a second membership function by selecting a greater one of each of said plurality of first membership functions obtained by the processing of said antecedent;

means for supplying an output in accordance with said second membership function;

means for obtaining a variance in accordance with the second membership functions; and

validity checking means for evaluating a reliability of output in accordance with said variance, wherein

said means for processing a value of an antecedent to obtain a plurality of first membership functions includes a memory for storing said plurality of first membership functions.