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EP0337423A2
Expired / Lapsed
EP
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Process control method and control system
Assignee: Hitachi Ltd
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Filing: 1989-04-12
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Granted: —
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Expires: 2009-04-12
Abstract
Abstract The feature of this invention is that in the various process control systems of plant the actions of the process are grasped as a qualitative model to which the fuzzy theory is applied to infer and control. The process control system chiefly comprises differentiation means (2) for determining the amounts of displacement of different process amounts with respect to time, qualitative fuzzy inference means (3) for making inference of qualitative process actions, and centroid arithmetic means (4) for converting the qualitative values of the inferred control target process amounts into the amount of control by a constant amount. The conventional linear control and fuzzy control system have a difficulty in the control of the process of which the local factors are suddenly changed to greatly affect the actions of the process. This invention is able to satisfactorily follow this sudden change and thus make high-precision control.
Inventors
- 👤 Haruki Inoue
- 👤 Motohisa Funabashi
- 👤 Masakazu Yahiro
- 👤 Fumiki Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 23:20
CPC Classifications
G; G06; G06N; G06N7/00; G06N7/02; G06N7/04; G05; G05B; G05B13/00; G05B13/02; G05B13/0265; G05B13/0275; Y; Y10; Y10S; Y10S706/00; Y10S706/90; Y10S706/902; Y10S706/903; Y10S706/906
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
133 words
A process control method capable of expressing the actions of a process by a qualitative differential equation, comprising the steps of: qualitatively evaluating different kinds of process information or change of information with respect to time resulting from differentiating said different kinds of process information in evaluation stages from appropriate values of membership function which are previously obtained by evaluating each kind of said information as fuzzy amount; qualitatively inferring future qualitative evaluation appropriate value set of control target process information by experiential rules on the basis of qualitative evaluation value set of appropriate values in each of said evaluation stages; and determining process control amounts from said inferred qualitative evaluation appropriate value set and said membership function of said control target process information previously evaluated as fuzzy amount by constant amount conversion.
Claim 2
Dependent Claim
133 words
A process control method capable of expressing the actions of a process by a qualitative differential equation, comprising the steps of: qualitatively evaluating different kinds of process information or change of information with respect to time resulting from differentiating said different kinds of process information in evaluation stages from appropriate values of membership function which are previously obtained by evaluating each kind of said information as fuzzy amount; qualitatively inferring future qualitative evaluation appropriate value set of control target process information by experiential rules on the basis of qualitative evaluation value set of appropriate values in each of said evaluation stages; and determining process control amounts from said inferred qualitative evaluation appropriate value set and said membership function of said control target process information previously evaluated as fuzzy amount by constant amount conversion.
Claim 3
Dependent Claim
164 words
A process control system comprising: differentiation means (2) which receives different kinds of process information and calculate amounts of change thereof with respect to time; qualitative evaluation means for evaluating said process information and/or said amounts of change of said process information with respect to time by a membership function previously evaluated by a fuzzy amount; qualitative inference means (3) for inferring qualitative evaluation value set of said control target process information after unit time by experiential rules on the basis of combinations of appropriate values in each of evaluation stages which are determined by said qualitative evaluation means; centroid arithmetic means (4) which receives said qualitative evaluation appropriate value set inferred by said qualitative inference means (3) and determines said amount of control of control target process information by centroid arithmetic processing (4) of said membership function predetermined for said target process information; and output means (5) for supplying said amount of control determined by said centroid arithmetic means (4) to a process.
Claim 4
Dependent Claim
164 words
A process control system comprising: differentiation means (2) which receives different kinds of process information and calculate amounts of change thereof with respect to time; qualitative evaluation means for evaluating said process information and/or said amounts of change of said process information with respect to time by a membership function previously evaluated by a fuzzy amount; qualitative inference means (3) for inferring qualitative evaluation value set of said control target process information after unit time by experiential rules on the basis of combinations of appropriate values in each of evaluation stages which are determined by said qualitative evaluation means; centroid arithmetic means (4) which receives said qualitative evaluation appropriate value set inferred by said qualitative inference means (3) and determines said amount of control of control target process information by centroid arithmetic processing (4) of said membership function predetermined for said target process information; and output means (5) for supplying said amount of control determined by said centroid arithmetic means (4) to a process.
Claim 5
Dependent Claim
50 words
A process control system according to Claim 2, wherein said differentiation means (2) has a plurality of differentiation units (21, 22, ... 2n) and memories (201, 202, ... 20n) for storing previously differentiated values connected in cascade and produces arbitrary-order amount of change of process amount with respect to time.
Claim 6
Dependent Claim
82 words
A process control system according to Claim 2, wherein said qualitative inference means (3) has a qualitative logic product inference unit (9) which assigns qualitative logic product rules made by experiential knowledge to said combinations of said appropriate values in each of said evaluation stages which are obtained by qualitatively evaluating said different kinds of process information or said amount of change of said process information with respect to time, and infers qualitative product evaluation set of said control target process information.
Claim 7
Dependent Claim
82 words
A process control system according to Claim 2, wherein said qualitative inference means (3) has a qualitative logic sum inference unit (10) which assigns qualitative logic sum rules obtained by experiential knowledge to said combinations of said appropriate values in each of said evaluation stages which are obtained by qualitatively evaluating said different kinds of process information or said amount of change of said process information with respect to time and infers qualitative sum evaluation set of said control target process information.
Claim 8
Dependent Claim
109 words
A process control system according to Claim 2, wherein when said qualitative values of said control target process amount are determined by the qualitative logic sum of said different kinds of process amount or the differentiated values thereof and the qualitative logic product thereof, said qualitative inference means (3) includes a qualitative logic product inference unit (9) which assigns qualitative logic product rules obtained to experiential rules, and a qualitative logic sum inference unit (10) which assigns qualitative logic sum rules to said experiential rule, and combines the qualitative product inference and the qualitative sum inference to thereby infer a qualitative evaluation set of said control target process information.
Claim 9
Dependent Claim
169 words
A process control system comprising: process input means (1) for receiving different kinds of information; differentiation means (2) for calculating amounts of change of said received process information with respect to time; qualitative evaluation inference means (3) for receiving said calculated different kinds of process information and inferring qualitative evaluation appropriate value set of control target process information; centroid arithmetic means (4) for receiving said qualitative evaluation appropriate value set inferred by said qualitative evaluation inference means (3) and determining said amount of control of said control target process information; process output means (5) for supplying said amount of control determined by said centroid arithmetic means (4) to a process; and feed-back identification means (20) provided between said centroid arithmetic means (4) and said process output means (5) so as to make repetitive processing of changing the amount of control until said control target process information enters within the allowable range of control target values and of feeding said amount of control back to said process input means (1).
Claim 10
Dependent Claim
169 words
A process control system comprising: process input means (1) for receiving different kinds of information; differentiation means (2) for calculating amounts of change of said received process information with respect to time; qualitative evaluation inference means (3) for receiving said calculated different kinds of process information and inferring qualitative evaluation appropriate value set of control target process information; centroid arithmetic means (4) for receiving said qualitative evaluation appropriate value set inferred by said qualitative evaluation inference means (3) and determining said amount of control of said control target process information; process output means (5) for supplying said amount of control determined by said centroid arithmetic means (4) to a process; and feed-back identification means (20) provided between said centroid arithmetic means (4) and said process output means (5) so as to make repetitive processing of changing the amount of control until said control target process information enters within the allowable range of control target values and of feeding said amount of control back to said process input means (1).
References Cited (Backward Citations)
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