Analogical inference method and apparatus for a control system

• US 4,777,585 A
• Filed: 02/03/1986
• Issued: 10/11/1988
• Est. Priority Date: 02/06/1985
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kokawa, Masasumi, Sasaki, Ryoichi, Onari, Mikihiko
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): MACDONALD, ALLEN R
• Application Number:
  US06/825,599
• Time in Patent Office: 981 Days
• Field of Search: 364/164, 364/184, 364/513
• US Class Current: 706/52
• CPC Class Codes: G05B 13/0275 using fuzzy logic only
• CPC Class Codes: Y10S 706/90 Fuzzy logic
• CPC Class Codes: Y10S 706/903 Control
• CPC Class Codes: Y10S 706/905 Vehicle or aerospace

Abstract

An analogical inference apparatus for control system is disclosed in which, in order to be able to generate a control signal to a system, which is to be controlled, even when conditions to be premised are unknown, the degree of similarity between the detected control signal from a sensor incorporated in the system and one of the predetermined control conditions stored in a memory is estimated by estimation means, and then a control value is inferred in accordance with the result of the estimation.

Claims

1. An analogical inference apparatus for a control system comprising:

detection means for detecting a present control condition;

storage means for storing a plurality of predetermined control conditions in the form of IF-conditions forming a part of an IF-THEN rule;

comparing means for comparing a detected control condition with said plurality of predetermined control conditions read out from said storage means to correlate said detected control condition with said predetermined control conditions and select a predetermined control condition related to said detected control condition;

estimation means for estimating the degree of similarity between said detected control condition and a predetermined control condition selected by said comparing means; and

analogical inference means for determining a control value, by analogical inference, on the basis of the estimated degree of similarity determined by said estimation means.

2. An anlogical inference apparatus for a control system according to claim 1, further comprising modifying means for modifying said control value in accordance with the estimated degree of similarity determined by said analogical inference means.

3. An apparatus according to claim 1, wherein said analogical inference means includes means for storing control rules, and inference control means for calculating control values by using a stored control rule and said degree of similarity.

4. An apparatus according to claim 3, wherein said control rules are expressed in a rule format.

5. An apparatus according to claim 3, wherein said analogical inference means includes correction means for correcting said control value in accordance with said degree of similarity.

6. An apparatus according to claim 1, wherein said analogical inference means includes fuzzy control means for determining said control value by a fuzzy control technique when said detected control condition and said predetermined control condition are equal and outputting said control value.

7. An apparatus according to claim 1, wherein said estimation means comprises for calculating the degree of similarity by using overlap of a concept structure for defining a control condition.

8. An analogical inference apparatus for a control system comprising:

detection means for detecting the control condition at a current time;

first storing means for storing known control conditions which are provided beforehand;

comparing means for comparing a detected control condition with a known control condition to examine whether the detected control conditon agrees with the known control condition and for outputting an agreement signal or non-agreement signal depending on the result of said comparing;

estimation means responsive to receipt of said non-agreement signal for estimating a degree of similarity between said detected control condition and said known control condition;

second storing menas for storing control rules;

analogical inference means for analogically inferring a control value by using an estimated degree of similarity and a control rule which is selected by using the estimated degree of similarity and determining the control value; and

fuzzy control means for determining a control value by a fuzzy control technique using said agreement signal and a control rule selected in accordance with said agreement signal.

9. An analogical inference method for a control system comprising the steps of:

storing in a storage device predetermined control conditons forming part of IF-THEN rules;

comparing the detected control condition with predetermined control conditions read out from said storage device to check whether or not said detected control condition agrees with any of said predetermined control condition;

estimating the degree of similarity between said detected control condition and a selected predetermined control conditon when no predetermined control condition exactly corresponds to said detected control condition; and

determining a control value, by analogical inference. on the basis of the estimated degree of similarity.

10. A method according to claim 9, wherein said determining by analogical inference includes the steps of storing control rules in a storage device, and calculating control values by using a stored control rule and said estimated degree of similarity.

11. A method according to claim 10, wherein said control rule is expressed in a rule form.

12. A method according to claim 10, wherein said analogical inference step includes the step of correcting said control value in accordance with said estimated degree of similarity.

13. A method according to claim 9, wherein said analogical inference step includes the step of determining said control value by a fuzzy control technique when said detected control conditon and said predetermined control conditon are equal and outputting said control value.

14. A method according to claim 9, wherein said estimating step comprises the step of calculating the degree of similarity by using overlap of a concept structure for defining a control condition.

15. An analogical inference method method for a control system comprising the steps of:

detecting a control condition at current time;

storing known control conditions which are provided beforehand in a storage device;

comparing the detected control condition with a known control condition obtained from said storage device to examine whether the detected control condition agrees with the known control condition and for outputting an agreement signal or a non-agreement signal depending on the result of said comparing;

receiving said non-agreement signal and estimating a degree of similarity between said detected control condition and said known control condition;

storing control rule in a storage device;

analigically inferring a control value by using an estimated degree of similarity and a control rule which is selected by using the estimated degree of similarity and determining the control value; and

determining the control value by a fuzzy control technique using said agreement signal and a control rule selected in accordance with said agreement signal.