JP2785320B2 - Expert system knowledge base management system. - Google Patents

Description

Description: BACKGROUND OF THE INVENTION A. Field of the Invention The present invention relates to an expert system, and more particularly, to an apparatus for managing inference data in a knowledge base.

B. Summary of the Invention In the expert system having the knowledge of the frame expression, the present invention stores a past value and a present value in a slot type of a frame and stores a statistic operation value using these values. By providing a time variable type, the data that changes with time can be managed by obtaining the characteristics of the time change for the slot name from the current value and the past value.

C. Prior Art The expert system is configured as shown in FIG. Knowledge of experts in each field (K
E) organizes and stores it in the knowledge base 1, and the inference engine 2 obtains an answer to the question from the user by inference using the knowledge of the knowledge base 1.

The inference engine 2 uses a description language such as LISP or PROLOG, and performs a priori inference while securing data of a knowledge base area, rules, facts, and the like necessary for a work process in a work environment (WM) 3. In addition, the knowledge base 1 is used to store the knowledge by using the man-machine interface of the knowledge base editor 4 and the debugger 5, and has an explanation function 6 with the user to accept a question intention and display an inference procedure.

The knowledge expression of the knowledge base 1 includes a production rule expression in the form of IF <condition part> THEN <conclusion part>, and a frame expression which expresses an abstract concept and an entity as a frame in a hierarchical network. A production system and a frame system that perform inference based on the above, and a hybrid system using both of them are known.

The knowledge rule based on the frame representation is such that a frame corresponding to a higher concept among frames is a class frame, a frame corresponding to a lower concept is an instance frame, and each frame has an attribute name (slot) and a description (value) indicating the attribute. , Value), and procedural knowledge (method) are described. For inference, a correct slot value is determined by inheritance (inheritance) for transferring a slot value from an upper frame to a lower frame.

D. Problems to be Solved by the Invention In a conventional expert system, the knowledge of a knowledge base adopts a data format and a knowledge expression according to the application field of the system. Here, in the frame format data, when new data is substituted for the slot value, the old slot value described so far is discarded, and the new data is replaced with the slot value. For this reason, a problem has arisen in which it is not possible to make inferences with reference to past values of slot values.

For example, when employing an expert system for monitoring and control found in plants and power systems, the retention and operation of time-series data occupies an important position in expressing knowledge, but in conventional knowledge management methods it changes over time. Inference using data and, consequently, monitoring control are not possible.

An object of the present invention is to provide a management device that manages data that changes with time and that can handle the data sufficiently efficiently.

E. Means and Actions for Solving the Problems In order to achieve the above object, the present invention provides a knowledge base represented by a frame as a knowledge representation and an inference that executes inference while securing areas, rules, and the like of the knowledge base. In an expert system having an engine, a frame in which a time variable type is provided in a slot type, and a buffer for holding a start cycle, a buffer size, and a current position of the buffer in order to manage a time variable of the time variable type frame Management information, statistic management information in which a statistic calculation permission flag and sample size information are written,
A current value slot into which a written value is substituted by the inference engine, and a plurality of time variable frames into which respective statistic values and attributes are written; and the past data values, attributes and time written into predetermined positions A buffer having a plurality of areas, referring to the statistics management information of the time variable frame, calculating the statistics while referring to the past data in the buffer when calculation is permitted, and determining a predetermined slot of the time variable frame. And a time variable management mechanism for writing calculation results to
The present value and the past value are stored in a slot type that changes with time, and a statistic is obtained as needed, so that inference can be performed by referring to the past value of the slot value.
In addition, the slot type setting ensures compatibility with the conventional frame system and facilitates handling.

F. Embodiment FIG. 1 is a time management configuration diagram showing an embodiment of the present invention. The frame 11 of the knowledge base 1 is provided with a time variable as a slot type in addition to the conventional frame format and its data storage function, and the concept of the time variable is added. The time variable frame 12 stores management information on the time variable added to each frame 11. Among the management information, the buffer management information stores a cycle in which the time variable management mechanism 14 described later is activated, the capacity of the buffer 13, the current position of the buffer 13, and the like. Information such as a predetermined statistics calculation permission flag and a sample size is written in the statistics management information. In the current value slot, a current value written by the inference engine 2 is placed, and an attribute handled by a conventional inference system, such as a certainty factor or a time tag, is added to the value.

In the statistics slot, various statistical calculation results having a time variable are stored, and specifically, the following values are stored.

(A) MAX [ΔT ₁ , ΔT ₂ ]: The maximum value in the data from _one minute before ΔT to _two minutes before ΔT.

(B) MIN [ΔT ₁ , ΔT ₂ ]: The minimum value in the data from _one minute before ΔT to _two minutes before ΔT.

(C) AVERAGE [ΔT ₁ , ΔT ₂ ]: average value in data.

(D) SUM [ΔT ₁ , ΔT ₂ ]: summation amount.

(E) RATE [ΔT, ΔS]: change amount during ΔS minutes before ΔT minutes in the past.

(F) In addition to the statistics described above, data such as the maximum value and minimum value of the change amount, the presence or absence of overshoot, the presence or absence of undershoot, and the presence or absence of a transient change are stored.

Next, in the buffer 13, the value of the event and the time of the event for various statistical calculations are written in time series together with the attribute by the time variable management mechanism 14. This buffer 13 has a circular structure, and when data is written to the end of the buffer 13, the value of the _first buffer 131 is updated at the next write.

The time variable management mechanism 14 is activated at regular intervals, and transfers the values and attributes in the current value slot of the time variable frame 12 to a predetermined position in the buffer 13 with reference to the buffer management information. At this time, the current position of the buffer is advanced by one and the buffer management information is updated, and at the same time, the time is transferred to the time item of the buffer 13 and the time is written. In addition, time variable management mechanism
14 refers to the statistics management information of the time variable frame 12,
If the calculation permission flag of the statistic K is YES, the statistic K is obtained by referring to the past data in the buffer 13, and the statistic K
Write the calculation result to the slot.

With the above configuration, the inference engine 2
When writing a value to the eleventh slot, if the slot type is a time variable, substitute the current value slot of the referenced time variable frame. Then, the current value slot value is transferred to the last slot of the buffer 13 at regular time intervals by the time variable management mechanism 14. Thereby, the buffer 13 and the current value slot of the time variable frame 12 are given, and the buffer management information is also updated. Further, for the statistic slot for which a flag is set from the statistic management information, the calculation of the statistic K is performed using the past data and the current value data of the buffer 13, and
The result is written to the statistics slot K.

Here, when referring to the value written in the buffer 13, since the buffer 13 is a data record collected discretely, the time of the statistical amount calculation request often does not match the time of the buffer. . At this time, the time variable management mechanism 14
Predicts the value of the requested time by interpolation with reference to a buffer slot value near the requested time.

Therefore, the present invention can be applied to an expert system for monitoring and control, and can manage data that changes with time, such as a change in water level. From this data, predictive control of monitoring and control of abnormality can be ensured. . In addition, knowledge base management can be performed so that statistics can be selected and the buffer is formed in a circular structure while efficiently maintaining the consistency with the conventional frame surface system.

G. Effects of the Invention As described above, according to the present invention, the time variable type is provided in the slot of the frame, and the current value and the past value and the statistic calculated using these are stored as the time variable frame. Therefore, there is an effect that the management of data that changes with time and the application to a supervisory control system or the like are facilitated while obtaining the consistency with the conventional frame.

[Brief description of the drawings]

FIG. 1 is a time management configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a basic configuration diagram of the expert system. 1 ... knowledge base, 2 ... inference engine, 11 ... frame, 12 ... time variable frame, 13 ... buffer, 14 ...
Time variable management mechanism.

Claims (1)

(57) [Claims] 1. An expert system having a knowledge base expressed as a frame as a knowledge expression and an inference engine for executing inference while securing an area and rules of the knowledge base, wherein a time variable type is provided in a slot type. In order to manage the frame and the time variable of this time variable type frame,
The buffer management information in which the start cycle, the buffer size and the current position of the buffer are held, the statistics management permission flag and the statistics management information in which the sample size information is written, and the value written by the inference engine are substituted. A plurality of time variable frames in which current value slots and respective statistic values and attributes are written; a buffer having a plurality of regions in which the past data values, attributes, and times are respectively written in predetermined positions; Time variable management which refers to the statistics management information of the time variable frame, calculates the statistics while referring to the past data in the buffer when calculation is permitted, and writes the calculation result in a predetermined slot of the time variable frame. A knowledge base management apparatus for an expert system, comprising: a mechanism;