JPH04117501A - Fuzzy combination type 2-freedom degree controller - Google Patents

Abstract

PURPOSE:To shorten the response time by converting the difference of membership function corresponding to the absolute value its difference into a signal of difference. CONSTITUTION:The difference delta = SV - SV0 is obtained by a subtractor means 11 between the control target value SV and the arithmetic target value SV0 against the stepped change of the value SV. Then the difference delta is sent to an absolute value means 12 and a multiplier means 14. Consequently, the means 14 outputs the multiplication value m(delta).delta which is increased at the velocity higher than a difference signal delta(= SV - SV0) that is received from the means 11 and gradually reduced. Therefore the response characteristic is speeded up by an adder means 15 at a certain time point, i.e., with a pre scribed difference delta2. Then the response time can be set the value SV.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention provides a two-degree-of-freedom PI or PID (P: proportional, I: integral) using a target value filter means.

D = Differential) related to the adjustment device, in particular, fuzzy combination type two-degree-of-freedom adjustment that simultaneously optimizes the suppression characteristics against disturbances to the controlled object and the follow-up characteristics against changes in the target value, while providing coordination with changes in the target value. Regarding equipment.

(Prior Art) A conventional target value filter type two-degree-of-freedom PI adjustment device is constructed as shown in FIG. That is, this adjustment device introduces the target value Sv into the target value filter means 1, performs arithmetic processing to make the proportional gain two degrees of freedom, and obtains the calculated target value Sv.
After obtaining Vo, this calculation target value Svo and the controlled object 2
(sv,
-pv) to find the deviation E. Furthermore, the deviation E obtained by the deviation calculating means 3 is K, +1-1/(TI
・S)) is guided to the Plj1 node means 4 having a transfer function, where PI adjustment calculation is performed to obtain the operation signal MV. Then, the operation signal MV and the disturbance are added and combined by the addition means 5, and then applied to the controlled object 2, thereby controlling the calculated target value 5vo - the control amount Pv. In the above equation, is the proportional gain, TI is the integration time, and S is the Laplace operator.

On the other hand, the target value filter means 1 has a coefficient means 1 for multiplying the target value SV introduced from the outside by a two-degree-of-freedom coefficient α of a proportional gain.
．． subtracting means 12 for subtracting the output of the subtracting means 12, a first-order lag element 19 that performs a first-order lag calculation using the integration time as a time constant on the output of the subtracting means 12, and outputting the result, a first-order lag element 19 for outputting the result of the first-order lag calculation using the integration time as a time constant;
and the coefficient means 1. It is constituted by adding means 14 and the like to obtain the calculation target value Svo by adding and synthesizing the outputs of the calculation target value Svo.

Therefore, in the control system as described above, the transfer function CPM(S) between P→MV and the transfer function C between S V and M V
SM(S) is CPM(S) −MV/PV−KP(1+1/T+−9
) ... (1) C5M(S) -MV/5V
−Kp(α+1/T1·S) (2). α is a two-degree-of-freedom coefficient (a constant that can be set between 0 and 1) for the proportional gain. Therefore, by determining ,T, so as to optimize the disturbance suppression characteristic, and then determining the coefficient α for increasing the proportional gain to 2 degrees of freedom so as to optimize the target value tracking characteristic, 2 degrees of freedom can be achieved. It can be achieved.

(Problem to be Solved by the Invention) By the way, the target value filter type two-degree-of-freedom adjustment device as described above has an excellent feature of being able to simultaneously optimize the disturbance suppression characteristic and the target value tracking characteristic. There is a problem that takes a long time to settle down.

Therefore, when considering the cause of this, it is found that the target value filter means 1 has at least one stage or two or more first-order delay elements, and when the target value Sv is changed in a stepwise manner, the target value of the step change is This is because it takes time for the value Sv to reach the final value due to the influence of the first-order lag element.

Furthermore, the influence of the first-order delay will be explained from the response characteristics shown in FIG. That is, FIG. 3 shows that when the target value Sv is changed stepwise in the apparatus of FIG. 4, the coefficient means 11
Only the output of (SM・α) changes stepwise, but the output of the subtraction means 1□ (SV・(1−α)) gradually increases due to the influence of the first-order lag element 13. As a result, the target value Sv approaches the target value Sv.

Assuming 5v-x%5VO-y, a digital calculation formula for the target value filter means 1 shown in FIG. 4 is obtained. First of all,
The transfer function of the target filter means 1 is as follows, and this (3)
Expressing the expression as a differential equation, it becomes. Here, by substituting the relational expression into this expression, we can obtain.

moreover, Transform this formula and, can be obtained.

7～ At point 1, the target value SV is When it changes to a dip shape, X if n≧2.

Therefore, the response characteristic in FIG. 3 is expressed by the above equation. In this equation (7), Δt is very small compared to TI, and (xa-yゎ-1) is also small, so the value in the latter stage of the opening equation becomes very small. Furthermore, the closer the output y, , I is to the input x, , the smaller the change in Δy. As a result, it will take a considerable amount of time for the output yfi to match the input X4. Of course,
Since this output y6 is the target value of the PI adjustment means 4, it takes a very long time to settle.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a fuzzy combination type two-degree-of-freedom adjustment device that can significantly and optionally shorten the response time to changes in target values compared to conventional methods. do.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention is provided with a target value filter means, and a target value obtained from the target value filter means side and a control from the controlled object. In a two-degree-of-freedom adjustment device that executes at least a PI adjustment calculation using the deviation from the amount and applies the obtained operation signal to the controlled object, the control target value introduced into the target value filter means and the target value filter A means for extracting the absolute value of the difference or a difference from the calculated target value obtained by the calculation of the means, and a fuzzy coefficient setting means for outputting a predetermined membership function in response to the absolute value or difference obtained by the means. This membership function is used to control the calculation target value to obtain the PI adjustment target value.

(Function) Therefore, by taking the above-described measures, the present invention predetermines the membership function corresponding to the absolute value or difference, and calculates the absolute value or difference of the difference between the control target value and the calculation target value. After taking out the signal, the membership function corresponding to the absolute value or difference is multiplied by the difference signal and added to the calculation target value to obtain the target value for PI adjustment. By increasing the response speed by thickening the membership function, the PI adjustment target value can be forcibly set to the control target value.

(Example) Hereinafter, an example of the present invention will be described with reference to FIG. In this figure, parts that are the same as those in FIG. 4 are given the same reference numerals, and a detailed explanation thereof will be omitted, and hereinafter, only the parts that are different from the conventional device will be described. That is,
In this device, a subtraction means 11 is provided between the control target value input terminal and the output terminal of the addition means 14, and an absolute value means 12 is provided on the output side of this subtraction means 11, and the control target value SV and the target value are Calculated target value S which is the output of filter means 1
The structure is such that the absolute value 1δ1 of the difference δ from vo is taken out, and a membership function m(δ) that takes a value from O to 1 is determined in advance in correspondence with the absolute value, and is obtained from the absolute value means 12. A fuzzy coefficient setting means 13 is provided for outputting a membership function m(δ) corresponding to the absolute value 1δ1, and a multiplication means 14 is provided for multiplying the output δ of the subtraction means 11 by the membership function m(δ). In addition, an addition means 15 is provided which adds the multiplication value obtained by the multiplication means 14 and the calculation target value SVo to obtain a PI adjustment target value SVa.

Therefore, according to the configuration of the embodiment as described above, for example, in response to a step-like change in the control target value Sv, the subtraction means
The difference between the control target value SV and the calculated target value SVO is δ-5V-
After determining 3VO, the difference δ is sent to the absolute value means 12 and the multiplication means 14.

After the absolute value means 12 calculates the absolute value 1δ1 of the difference δ, it is introduced into the fuzzy coefficient setting means 13.

In this fuzzy coefficient setting means 13, the difference δ-(sv
-sv. ) becomes smaller than a value that does not impede the original two-degree-of-freedom function, for example, δ2, and as the value of the difference δ2 decreases, for example, the difference δ shown in the figure changes exponentially from O to 1. Membership function m that takes a value
(δ) and sends it to the multiplication means 14. the result,
Since the multiplication means 14 outputs the multiplication value m(δ)·δ which increases at a faster speed than the speed of the gradually decreasing difference signal δ(-SVSVo) sent from the subtraction means 11, From the adding means 15 at a certain point in time.

In other words, from the time ta when the predetermined difference δ2 is reached, (b) in FIG.
As shown in , the response characteristic becomes faster and settles to the control target value S■.

Note that the fuzzy coefficient setting means 13 and the like may be realized by hardware using resistors, capacitors, and semiconductors, or may be realized by software using a computer.

Next, another embodiment of the present invention will be described with reference to FIG. In this case as well, the same parts as in FIG. 4 are given the same reference numerals, and detailed explanation thereof will be omitted, and only the different parts will be explained below.

That is, this embodiment has a configuration in which the absolute value means 12 is removed from FIG. The membership function m(
δ). Of course, this positive and negative membership function m(δ) can be set differently.

Next, the operation of the apparatus configured as above will be explained. The target value SVa for PI adjustment in this device is SV a −S Vo 1 m (δ) (SV-8
Vo)... (8) It is expressed as follows.

Now, when the control target value SV changes stepwise, the difference δ between (SV-8Vo) is large and δ2≦δ
...Since the relationship is as shown in (9), the membership function is m(δ)−〇, and the above (8
) from the equation, S V a = S V o. In other words,
is determined only by the transfer function of the target value filter means 1, and is introduced into the deviation calculation means 3 as a target value for PI adjustment. Therefore, in this case, exactly the same response characteristics as the conventional device can be obtained.

Thereafter, when the difference δ obtained from the subtraction means 11 becomes smaller than δ2 and the relationship δ1≦δ×δ2 (11) is established, the membership function from the fuzzy coefficient setting means 13' becomes 0 m(δ ) is 1, and from the above equation (8), S V a −S V0+m (δ)x(SV 5V
o)...(12) This SVa is sent to the deviation calculating means 3 as a target value for PI adjustment. Therefore, in this case, the difference δ is the difference δ
When it becomes smaller than 2, the response characteristic becomes faster than the conventional response characteristic as shown in (b) of FIG. 3, and it approaches the control target value Sv.

Furthermore, when the difference δ obtained from the subtraction means 11 becomes smaller and the relationship becomes 0≦δ×δ1 (13), the membership function becomes m(δ)−1, and from the above equation (8), , 5Va-8V
-(14), and the control target value Sv is directly sent to the deviation calculation means 3 as the PI adjustment target value.

As a result, the target value for PI adjustment becomes the difference δ, the time tb
Since the control target value S is forcibly set to the control target value S■, it can be settled in a much shorter time than in the past.

Therefore, according to the configuration of the embodiment as described above, when the calculated target value Svo of the target value filter means 1 approaches the control target value Sv, that is, when the difference between both target values becomes equal to or less than the predetermined value 62, Since the PI adjustment target value SVa is forcibly and quickly transferred from the calculated target value Svo of the target value filter means 1 to the control target value SV using the membership function, it does not affect the function of two degrees of freedom. The target value follow-up time can be greatly shortened, the performance of this type of two-degree-of-freedom adjustment device can be greatly improved, and by being scattered throughout the plant, it can greatly contribute to improving the plant operating characteristics.

In the above embodiment, the multiplication value of the output of the subtraction means 11 and the membership function is supplied to the addition means 15, but for example, the multiplication means 14 may be omitted and a value corresponding to the multiplication value may be supplied to the fuzzy coefficient setting means 13. .13' and added to the adding means 15. Also, PI style ji
Although the i5 calculation has been described, it goes without saying that the same can be applied to the PID adjustment calculation. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] As explained above, the present invention provides a fuzzy combination type two-degree-of-freedom adjustment device that can significantly shorten the response time to changes in target values compared to the conventional method and greatly contributes to improved performance. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the fuzzy combination type two-degree-of-freedom adjustment device according to the present invention, FIG. 2 is a block diagram showing another embodiment of the device of the present invention, and FIG. 3 is a conventional device. FIG. 4 is a block configuration diagram of the conventional device. DESCRIPTION OF SYMBOLS 1...Target value filter means, 2...Controlled object, 3.
... Deviation calculating means, 4... PI or PID adjusting means, 11... Subtracting means, 12... Absolute value means, 13.
13'... Fuzzy coefficient setting means, 14... Multiplication means, 5... Addition means.

Claims (1)

[Claims] Target value filter means is provided, and at least PI (P: proportional, I: integral) adjustment is performed using the deviation between the target value obtained from the target value filter means and the controlled amount from the controlled object. In a two-degree-of-freedom adjustment device that executes a calculation and applies the obtained operation signal to the controlled object, the control target value introduced into the target value filter means, the calculated target value obtained by the calculation of this target value filter means, and and fuzzy coefficient setting means for outputting a predetermined membership function corresponding to the absolute value or difference extracted by this means, and the said calculation is performed using this membership function. A fuzzy combinational two-degree-of-freedom adjustment device characterized by controlling a target value to obtain the target value for PI adjustment.