JPS63313224A - Rule setting system for fuzzy control - Google Patents

Abstract

PURPOSE:To simply execute a definition of a function by dividing a membership function for defining a fuzzy set into plural sections, and setting a partial membership function at every section and synthesizing these functions. CONSTITUTION:A device for a rule setting system is constituted of a storage device 1 for holding a rule group consisting of a membership function and an estimation rule, a display device 2, an input device (mouse) 3, a temporary storage device 4, and an arithmetic unit 5. In this state, the membership function is divided into plural sections, a partial membership function is set at every section, and these partial membership functions are synthesized, by which a desired membership function is constituted. In this case, setting of the partial function in every section is executed by selecting it from a prescribed candidate, based on the value of a range being desirable as the form of an instructed fundamental function and the function value of some point in a defined area. Also, at the time of setting, the estimation rule related thereto is displayed.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a rule setting method suitable for a control system in which human knowledge and experience are expressed in rules and used for control by a computer. .

[Conventional technology]

In fuzzy control systems that quantify human state recognition using fuzzy sets and use it for control, human experience is expressed by rules consisting of membership functions and estimation rules. The estimation rule here is expressed, for example, in the form of "If XXX (precondition part), . . . do (command part)." Further, in the precondition section, a proposition such as, for example, "r temperature is high" is written, and the meaning of the proposition is defined by the membership function.

Conventionally, the above membership function has been defined independently of the estimation rule, and its setting is described in, for example, Japanese Patent Laid-Open No. 60-20
As seen in Japanese Patent No. 4002, a method of defining a basic function such as a normal distribution, a triangle, a trapezoid, etc. prepared in advance was selected and inputting several numerical values defining the function was used. The fuzzy control is detailed in the September 16, 1985 issue of the magazine "Nikkei Computer", pages 47 and 65.

(Problems to be Solved by the Invention) In the above-mentioned prior art, the shape of the basic function used to define the membership function is defined in advance, so knowledge about the basic function is required, and the membership function that can be defined In addition, since human thoughts are expressed using basic functions prepared in advance, it is a heavy burden on humans, and it is difficult to set rules that have the desired meaning.

Furthermore, when creating a membership function, the relationship between the fuzzy set defined by the membership function and the fuzzy estimation rule using this is important, but conventionally it has not been possible to refer to these at the same time.

An object of the present invention is to provide a rule setting method that expresses human thoughts as rules as they are and can be easily defined.

Means for Solving Problem C] To achieve the above object, the present invention divides a membership function that defines a fuzzy set into a plurality of intervals, sets partial membership functions for each interval, and The desired membership function is constructed by composing the partial membership functions of .

In this case, the setting of the partial membership function for each interval is
Based on the shape of the specified basic function and the range of values desired as the membership function value at a certain point within the domain, multiple partial membership function candidates passing through the above range connected to already defined adjacent intervals are generated. This is done by selecting from among them. Also, when setting a membership function, the estimation rules related to this are displayed.

[Effect]

According to the present invention, since one membership function is obtained by combining a plurality of partial membership functions, it is possible to set a membership function that is close to the image that a person imagines in his or her head. In addition, since the setting of each partial membership function is performed by selecting from partial membership function candidates displayed in advance on the display screen, the rule creator must be aware of the mathematical meaning and expression method of the basic function. This eliminates the need to do so, reducing the burden on rule creators. Furthermore, since the membership functions and related fuzzy estimation rules are displayed on the same screen, the rule creator can always pay close attention to the fuzzy estimation rules and membership functions, and can save their brain. It becomes possible to set appropriate rules that match the situation being considered.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of the display screen of the display device 2 and the human-powered device 3. In FIG. 201 is a membership function display screen that defines the selected proposition; 202 is a fuzzy estimation rule related to fate displayed on membership function display screen 201; 205 is a membership display screen that displays partial membership function candidates that pass through the range set by the rule creator. Also, 210
Finish setting the membership function and mnemonic! ! 211 is the section selection area selected when the section in which the partial membership function is defined is specified; 212 is the membership function display screen 20
1. A range selection area selected when a change in function value at a certain point within the domain of the membership function above is instructed; 2.
13 is an adoption selection area selected when adoption of a partial membership function is instructed from among a plurality of partial membership functions on the membership function candidate display screen 205; 2001.13;
2002 is a function selection area used when a basic function prepared in advance is selected.

For example, in the function 1 selection area 2001, a > O1 initial parameter is a = 2500
.

b=100), and the function 2 selection area 2002 is assigned (however, a>O1 initial parameter is a=100°b=100). The input table N3 is a mouse 3 whose movement moves the arrow on the display screen.
03, and a button 304 which, when pressed, selects an instruction on the display device 2.

FIG. 2 shows a block diagram of a device implementing the rule setting scheme according to the invention. In the figure, 1 is a storage device for holding a group of rules each consisting of a membership function and an estimation rule, 2 is a display device for displaying the rules,
3 is an input device for instructing function selection, etc. (in this embodiment, input using a mouse is considered); 4 is a temporary storage device for holding information during membership function setting; 5
is an arithmetic device that performs various operations such as creating a membership function based on points input from the input device 2.

FIG. 3 shows an example of the storage contents of the -order storage device W4. The domain of one membership function is set to be divided into a maximum of N sections, and the -order storage device 4 has each section 41. Basic function number 4 that defines a partial membership function for
2 and a parameter 43 that defines the shape of its basic function.

FIG. 4 is a diagram showing the relationship between the conceptual membership function that the operator is trying to obtain and the created membership function. In the figure, 50 is a membership function drawn in the mind of the rule creator, and 51 is a membership function created using this method.

FIG. 5 shows an example of a processing procedure by the arithmetic device 5 that implements the rule setting method according to the present invention. In the present invention, first, using the mouse 303, move the arrow on the display device 2 to the position of the desired proposition in the proposition list display screen 200, and select the domain related to the designated fate by picking the button 304. etc. (process 600). If the selected proposition has already been defined in the membership function (601), it is written out from the storage device 1 to the primary storage device 48 and displayed on the membership function display screen 201 (60
2). On the other hand, if the membership function is undefined, the interval for setting the partial membership function is taken as a preparation for the entire domain Cxs*XI (603). For example, for a proposition such as "The temperature is high, If the domain (0,100) is read in the process 600, this is set as an interval.If there is a fuzzy estimation rule related to the selected proposition (604), all the corresponding fuzzy estimation rules are related estimation. It is displayed on the rule display screen 202 (605).

Note that if there is no fuzzy estimation rule regarding the proposition specified in process 604, nothing is displayed.

After that, it waits for input from the rule creator to set the membership function (606), reads to which region the coordinate value picked by the rule creator belongs,
Select the next instruction (60)).

When either function selection area 2000 or 2001 is picked, either basic function 1 or basic function 2 is selected (608). A standard membership function is displayed on the membership function display screen 201 using the initial parameters prepared in advance for the selected basic function (609
), for example, among the basic functions 1.2 mentioned above, basic function 2
Assuming that is selected, the trajectory of will be displayed in the interval (0,100).

When the range selection area 212 is checked in step 606, the instruction "range" is selected, and as shown in FIG.
y) (yo<y) and set the range for changing the membership function value at X' to [yo.

yzl (810). In the arithmetic unit 5, the range [yo
After dividing t yzl into m equal parts, take the current function value at the boundary point of one section by changing parameters a and b,
And the function value at Xl is membership function candidate 1
For example, if the division is divided into four equal parts as shown in FIG. 2, five partial membership function candidates can be obtained on the membership function candidate group display screen 20.
5 (612), calculate partial membership functions based on the picked coordinates on the locus drawn by the partial membership function candidates (613), and display them on the membership display screen 201 (614). .

Further, when the section selection area 211 is picked in process 606, the instruction "section" is selected, and the next two picked points (
xo, 0)-(xz, 0) (xo<xz) is read and set as an interval (xo, xz) (615).

At that time, if the old section and the new section overlap, the old section and the new section are changed so that they do not overlap (616).

In other words, the old section is [0,fool and the new section is [68,
OOO], the old interval is changed to [0,68].

Similarly, when the adoption selection area 213 is picked in process 606, the interval, basic function number, and parameters that define the partial membership function being displayed on the membership function display screen 201 are written to the primary storage device 4 (617). , otherwise, wait for loading again.

When these processes are completed, the process waits until the next instruction is input (618), and if an area other than the end selection area 210 is picked, processes 607 to 618 are repeated.

Now, assume that the rule creator performs the above processing while assuming the membership function 50 of FIG. 4, and defines the function as follows.

At this time, the -order storage device 4 stores the membership function f (x
) is stored in a format such as 51 in FIG.

When the instruction “End” is selected by picking the end selection area 210 (618), the domain (x S ?X!>
The section written in the second storage device 4 is compared to see if there is an undefined section (619).

If there is an undefined section, it displays a message (620), waits for rereading (606), performs the subsequent processing, and resets the membership function. If there is no undefined interval,
- Next, write all the information in the storage device 4 to the storage device 1 (621), and end.

According to the embodiments described above, it is possible to create and change membership functions simply by inputting from the mouse 3, and it is possible to create human-friendly rules.

Note that as an input means, for example, a keyboard, a light pen, etc. may be used in addition to the mouse, and a function written by hand using OCR or the like may be read and set as the initial input of the membership function.

(Effects of the Invention) As is clear from the above description, according to the present invention, membership functions can be set with simple inputs such as selecting a few points and basic functions, etc. knowledge is not required, and the number of rule creators can be expanded.In addition, each membership function is composed of a composite function of partial membership functions, and each partial membership function is a composite function of multiple partial membership functions. Since the membership functions are set by selecting from the following, it is possible for the rule creator to create a membership function that is close to the image he or she has in mind.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a display screen and a human-powered device, FIG. 2 is a block diagram showing the configuration of a device implementing the present invention, and FIG. 3 is an example of data stored in the primary storage device 4. Figure 4 is a diagram showing a function between the membership function 50 in the mind of the rule creator and the membership function 51 actually set, and Figure 5 shows an example of a processing procedure for realizing the present invention. It is a flowchart. DESCRIPTION OF SYMBOLS 1...Storage device, 2...Display device, 3...Input device, 4...-Storage device, 5... Arithmetic device.

Claims (1)

[Claims] 1. Divide the domain of each membership function applied to fuzzy control into multiple intervals, and interactively select the partial membership function for each interval from among multiple partial membership function candidates prepared in advance. A rule setting for fuzzy control characterized in that the fuzzy estimation rules related to the membership function are displayed on the display screen at the time when the membership function is set. method.