JPS62162102A - Optimum parameter searching device - Google Patents

Abstract

PURPOSE:To reduce the number of times of searching to find the optimum parameter and heighten accuracy of searching by providing an evaluation function arithmetic means, an automatic searching pitch setting means and an optimum parameter value arithmetic means. CONSTITUTION:Control deflection 5 is inputted to an evaluation function value computing element 6 and an evaluation function value (y) for a parameter (x) is obtained. An automatic direction of increase and decrease of parameter and pitch setting circuit 12 finds searching pitch DELTAx of this time from parameter (x) found last time and the time before that and corresponding (y) and outputs it to an optimum parameter value calculating circuit 9. The optimum parameter value calculating circuit 9 finds the optimum parameter (x) at the automatically set searching pitch, and the optimum parameter (x) thus found is indicated in a parameter indicator 10. Thus, a regulating worker can regulate the parameter 11 of a PID regulator 1 based on the indication of the parameter indicator 10.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to: 1. For example, optimal control parameters such as the parameters of a PID controller, such as proportional gain, reset rate, and differential time, are searched with a small number of searches and with high accuracy. This invention relates to an optimal parameter search device.

[Conventional technology]

Various devices have been proposed in the past for determining optimal control parameters of a control system from an evaluation function and performing optimization tests.

FIG. 3 shows the configuration of a conventional optimal parameter search device.

In the figure, reference numeral 1 denotes a PID adjuster, which controls the controlled object 2 by setting control parameters searched for by a method described later. The output of the controlled object 2 is subtracted from the target value 3 by the subtracter 4, and is inputted to the PID controller 1 as the control Il deviation 5.

The optimal parameter search is performed as follows.

First, from the control deviation 5, the evaluation function value calculator 6 calculates the evaluation function @
Find y and set the parameter x1 at that time as the initial value. Next, the parameter
A search for the optimal parameter X is performed. FIG. 4 shows the state of this search. In the figure, ◯ indicates a case where the search is performed at a constant pitch, and ◯ indicates a case where the search is performed at a constant ratio.

[Problem that the invention seeks to solve]

As is clear from FIG. 4, the search using a constant pitch has the drawback that it takes many times to reach the minimum value of the evaluation function, that is, the optimum parameter, and the search time becomes long. On the other hand, the search using a constant ratio depends on the value of the ratio, but if the ratio is large, the number of times it takes to pass the minimum value of the evaluation function is small, but the pitch near the minimum value becomes rough, and the minimum (direct parameter) There is a drawback that the search accuracy for X decreases.Furthermore, if the ratio is made smaller, the search accuracy for the parameter X increases, but the number of times it takes to reach the minimum value increases, resulting in a longer search time.

The present invention has been made based on such problems, and an object of the present invention is to provide an optimal parameter search device that requires fewer searches until the optimal parameter is searched and has good search accuracy.

[Means for solving problems]

In the present invention, R
In the general parameter search system, an evaluation function calculation means for calculating an evaluation function from the search parameters, and a search pitch automatic setting means for automatically setting the next search pitch from the evaluation function obtained by the evaluation function calculation means and the search parameters. and an optimum parameter value calculation means for sequentially calculating the evaluation function using the search pitch set by the search pitch automatic setting means to obtain the optimum parameter value.

[Effect]

When the search parameter is x and the evaluation function is y, the search pitch automatic setting means uses the 2
A straight line connecting the x and y coordinates of the points and a predetermined yi parallel to the X axis
The next search pitch Δx is determined from the intersection with the reference line having l. Then, when this search pitch Δx is determined twice, the y value of the next reference line is set to 1/n (n>
1) and then repeat this to find the x and y coordinates. If the two search pitches Δx found on the same reference line
When the search pitch ΔX obtained after the search pitch Δxtfi obtained earlier is smaller than the search pitch ΔX obtained after the search pitch Δxtfi, the previously obtained Find the current X value based on the straight line connecting the coordinates of .

Next, the optimum parameter value calculation means sets the reference line to the arithmetic average value of the previous and two previous reference lines, calculates the X value in the same manner, and outputs the obtained X value as the optimum parameter.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an R-parameter searching device according to this embodiment.

The aforementioned control aS difference 5 is input to the evaluation function value calculator 6, where the evaluation function value y for the parameter X is determined. The automatic parameter increase/decrease direction and pitch setting circuit 12 determines the current search pitch Δx from the parameter The R-optimal parameter value calculation circuit 9 calculates the optimum parameter X using the search pitch set by vJ. The determined R-suitable parameter X is displayed on the parameter display 10. As a result, the adjuster can adjust the parameters 11 of the PID controller 1 based on the display on the parameter display 10.

Next, a method for determining search bits and a method for searching for optimal parameters, which are the gist of this embodiment, will be explained.

FIG. 2 is a diagram showing the relationship between parameter X and evaluation function y. first. Find the evaluation function y1 for the parameter x1, then increase the parameter X a little to x2, and then
The evaluation function y2 for 2 is determined. As a result, two points ■ and ■ are found.

Next, find the intersection between the extension of the straight line connecting these ■ and ■ and the reference line indicated by y=ya. In addition, ya −yl
/n, and is set to n=2 in this embodiment. Let the X coordinate of the intersection of both lines be x3, and find ya from this x3. Next, these x3. Point ■ and point ■ found from ya
Find the next parameter x4 from the intersection of the extension line of the straight line connecting them and the reference line y=ya, find y4 from x4, and find the point ■
get. At this time, two search pitches Δx2 (-x3-x2) with the same reference line y=ya.

Since Δx3 (=x4-x3) has been found, the reference line is next changed to y=yb (-Va/n). Similarly, find x5 from the intersection of the extension of the straight line connecting points ■ and ■ and the reference line y=yb, find y5 from this x5, and point ■
get. Furthermore, x6 is obtained from the intersection of the extension line of the straight line connecting points ■ and ■ and the reference line y=yb, and from this x6, yc
Find the point ■ by 1q. Similarly, the reference line y=yc (-
Find the points ■ and ■ from Vb/n) and set the reference line y=yd (
=yc/'n) to find ■ and @l.

However, when it comes to finding ■, the search pitch Δx8
(=x9−x8) is the search pitch Δx 9 (
= x 1o −x 9 ), indicating that the minimum value is close. Therefore, in this case, xlO is not adopted as is, but a certain ratio restriction is added. Here, m=1.1, and a value obtained by multiplying ×9 by 1.1 is adopted as xlo. In addition, if xlo decreases with respect to x9, the value obtained by multiplying x9 by 1/1.1 is
It may be adopted as lo.

In this way, if the second search pitch width obtained from the same reference line exceeds that of the first search, the following standard 1y=ye
is the arithmetic mean of yc and yd, that is, Ve = (yc
+yd), /2, and find xll from the intersection of the extension of the straight line connecting ■ and [stock] and the above reference line. The obtained xll is then output to the parameter display 10 as the optimal parameter. Optimal control parameters are thus provided to the PID regulator 1. Good control is provided.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide an optimal parameter search device that can reduce the number of searches required to search for an optimal parameter and has good search accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an optimal parameter search device according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining the operation of the device and shows the relationship between the search parameter X and the evaluation function y. Figure 3 shows the conventional optimal parameter search S;!
FIG. 4 is a block diagram showing the configuration of the device, and is a diagram for explaining the operation of the device, and is a diagram showing the relationship between the search parameter X and the evaluation function y. 1...PID controller, 3...Target value, 4...Subtractor, 5...Control deviation. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 2 Figure 4

Claims (1)

[Claims] An optimal parameter search device that searches for optimal control parameters for a control system includes an evaluation function calculating means for calculating an evaluation function from the search parameters, and calculating the next search pitch from the evaluation function obtained by the evaluation function calculating means and the search parameters. The apparatus includes an automatic search pitch setting means for automatically setting the search pitch, and an optimum parameter value calculation means for sequentially calculating the evaluation function at the search pitch set by the search pitch automatic setting means to obtain the optimum parameter value, When the function is y, find the next search pitch Δx from the intersection of the straight line connecting the x and y coordinates of the two points obtained in the previous and two previous times and the reference line with a predetermined y value parallel to the x axis. , Once this search pitch Δx has been found twice, change the next reference line to 1/n (n>1) of the previous reference line, repeat this to find the x, y coordinates, and calculate 2 using the same reference line. When the search pitch Δx obtained earlier is smaller than the search pitch Δx obtained later among the search pitches Δx, the x value obtained earlier is multiplied by m and the x, y coordinates are calculated again. , find the current x value based on the straight line connecting this and the coordinates before the previous time,
Next, the reference line is set to the arithmetic average value of the previous and two previous reference lines, the x value is obtained in the same way, and the obtained x value is output as the optimal parameter. Parameter search device.