JP2809849B2 - 2-DOF adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to two-degree-of-freedom P1 or PID (P: proportional, I: integral, D: derivative) adjustment using a target value filter means. Related to the device,
In particular, the present invention relates to a two-degree-of-freedom adjustment device that simultaneously optimizes a suppression characteristic for disturbance to a control target and a follow-up characteristic for a change in a target value, and has a quick response to a change in a target value.

(Prior Art) A conventional target value filter type two-degree-of-freedom PI adjustment device is configured as shown in FIG. That is, the adjusting device introduces the target value SV into the target value filter means 1 and performs a calculation process for making the proportional gain two degrees of freedom, thereby performing the calculation target value SV _0.
After obtaining, seek led to this operation target value SV ₀ and the controlled variable PV from the control object 2 to the deviation operation means 3 (SV ₀ -PV) becomes operational by the deviation E. Further, the deviation E obtained by the deviation calculation means 3 is led to a PI adjustment means 4 having a transfer function of K _P {1 + 1 / (T ₁ · S)}, where a PI adjustment calculation is performed to obtain an operation signal MV. . Then, the operation signal MV and the disturbance D are added and synthesized by the adding means 5 and then applied to the control target 2 so that the calculation target value SV ₀ is controlled to be equal to the control amount PV. Note that K _P In the above equation proportional gain, T _I is the integral time, S is a Laplace operator.

Meanwhile, the target value filter means 1, multiplication means 1 ₁ for multiplying the second free cathodic coefficient proportional gain α with respect to the target value SV introduced from outside, subtracts the output of coefficient unit 1 ₁ from the target value SV subtracting means 1 _2, the subtraction means 1 _second output for time integration time constant to be first-order lag output by performing the calculation primary delay element 1 _3, the first-order lag element 1 _third output and said coefficient means It is constituted by a _first output and additive synthesis to adding means 1 ₄ like to obtain a calculation target value SV _0.

Therefore, the transfer function C _PM (S) between PV → MV and the transfer function C _SM (S) between SV → MV in the above control system are respectively C _PM (S) = − MV / PV = K _{P (1 + 1 / T I ·} S) ... (1) C SM (S) = - MV / SV = K P (α + 1 / T I · S) ... a (2). α is a coefficient of two degrees of freedom of the proportional gain (a constant that can be set between 0 and 1). Therefore, if K _P and T _I are determined so that the disturbance suppression characteristic is optimal, and then the two-degree-of-freedom coefficient α of the proportional gain is determined so that the target value tracking characteristic is optimal, the two-degree of freedom is obtained. Can be achieved.

(Problems to be Solved by the Invention) Incidentally, the target value filter type two-degree-of-freedom adjusting device as described above has an excellent feature that the disturbance suppression characteristic and the target value follow-up characteristic can be simultaneously optimized. There is a problem that it takes a long time to settle.

Considering this cause, the target value filter means 1 has at least one or two or more first-order lag elements, and when the target value SV is changed stepwise, the target of the step change is changed. This is because it takes time for the value SV to reach the final value under the influence of the first-order delay element.

Further, the effect of the first-order lag will be described with reference to the response characteristics in FIG. In other words, the third figure when the target value SV is changed stepwise in the apparatus of FIG. 4, but which is the output of the coefficient unit ₁ 1 (SV · α) is changed stepwise,
A output which subtracting unit _{1 2 {SV · (1-} α)} will be approached rises gradually under the influence of first order lag element 1 ₃ to the target value SV.

Therefore, SV = X and SV ₀ = Y, and a digital operation expression of the target value filter means 1 shown in FIG. 4 is obtained. First, the transfer function of the target filter means 1 is When this equation (3) is expressed by a differential equation, Becomes Here, for this equation (4), Substituting the relation Can be obtained. Furthermore, by transforming this equation, Can be obtained.

Now, when the target value SV is changed stepwise at the time of n = 1, since the In _{n ≧ 2 x n = x n} -1, from the response characteristic of Figure 3 is the formula (6), become that way. The (7) Delta] t is very small compared to T _I In the equation, and since (x _n -y _n-1) is small, the subsequent value of the equation is very small. Moreover, the closer the output y _n-1 approaches the input x _n , the smaller the change in Δy _n . As a result, the output y _n would take considerable long time to match the input x _n. Of course, the output y _n so has become a target value of the PI regulation means 4, the settling time it takes very long.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a two-degree-of-freedom adjusting apparatus capable of arbitrarily shortening a response time with respect to a change in a target value as compared with the related art.

[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 calculates a control target value to be introduced by the target value filter means. At least PI (P: proportional, I: integral) adjustment calculation is executed using the deviation between the calculated target value and the control amount from the control target, and an operation signal obtained by this adjustment calculation is applied to the control target 2 Means for extracting an absolute value of a difference between a control target value to be introduced to the target value filter means and a first calculation target value obtained by calculation of the target value filter means, or a difference between the two target value; A membership function that takes a value of 0 to 1 corresponding to the absolute value difference or both target value differences is set in advance, and the membership function corresponding to the absolute value or both target value differences extracted by the means is set. And the membership function output from the membership function setting means is multiplied by the difference between the two target values, and the first calculated target value is calculated using the obtained multiplication value. A calculation target value correcting means for correcting and obtaining a second calculation target value, wherein the deviation is obtained from the second calculation target value and a control amount from the control target.

(Operation) Therefore, by taking the above means, the present invention provides the absolute value of the difference between the control target value and the first calculation target value or the difference between the control target value and the first calculation target value in advance. A membership function corresponding to the difference between the two target values is determined, and after extracting these absolute values or the difference between the two target values, the membership function corresponding to the absolute value or the difference between the two target values is extracted to obtain the difference between the two target values. Is multiplied with the first calculation target value and added and synthesized with the first calculation target value to obtain the second calculation target value. Therefore, by increasing the membership function from a certain absolute value or a difference between the two target values, the response characteristic can be increased. Second, the calculation target value can be forcibly settled to the control target value.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG. 4, the same parts as those in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. Hereinafter, only different parts from the conventional apparatus will be described. That is, in this apparatus, the control target value input and adding means 1 ₄
And an absolute value means 12 provided on the output side of the subtraction means 11, so that the control target value SV and the first calculation target value SV which is the output of the target value filter means 1 are provided.
The absolute value | δ | of the difference δ from ₀ is taken out,
Also, a membership function m (δ) taking a value of 0 to 1 corresponding to the absolute value is determined in advance, and a membership function m corresponding to the absolute value | δ |
A membership function setting means 13 for outputting (δ) is provided, and a multiplication means 14 for multiplying the output δ of the subtraction means 11 by the membership function m (δ) is provided. multiplication value and the first operational target value SV ₀ and adding means 15, the second operation target value SVa by adding is provided with.

Therefore, according to the configuration of the embodiment as described above, for example, for the stepwise change of the control target value SV, the difference δ = SV between the control target value SV and the first calculation target value SV ₀ is calculated by the subtraction means 11. −SV ₀
, And sends the difference δ to the absolute value means 12 and the multiplication means 14. In the absolute value means 12, the absolute value | δ |
After that, it is introduced into the membership function setting means 13.

In the membership function setting means 13, the difference δ =
(SV-SV ₀₎ when is smaller than value that does not for example [delta] ₂ inhibits the function of the original two-degree-of-freedom of, between, for example, index until the difference [delta] ₁ to example depicted in accordance smaller the value [delta] ₂ of the difference A membership function m (δ) that functionally takes a value of 0 → 1 is output and sent to the multiplication means 14. as a result,
The multiplying means 14 outputs a multiplied value m (δ) · δ which increases at a speed higher than the speed of the gradually decreasing difference signal δ (= SV−SV ₀ ) sent from the subtracting means 11, so that the addition is performed. some point from means 15, that is to settle the control target value SV in response characteristic faster as shown in the time ta that a predetermined difference [delta] ₂ of FIG. 3 (b).

The membership function setting means 13 and the like may be realized by hardware using a resistor, a capacitor, or a semiconductor, or may be realized by software using a computer.

Next, another embodiment of the present invention will be described with reference to FIG. Also in this case, the same parts as those in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. Only different parts will be described below.

That is, this embodiment has a configuration obtained by removing the absolute value means 12 from Figure 1, the membership function setting unit 13 along with this' of the positive and negative of the difference between the control target value SV and arithmetic target value SV ₀ Membership function m (δ) separately corresponding to value
Set. Of course, this positive and negative membership function m
(Δ) can be set differently.

Next, the operation of the device configured as described above will be described. Second arithmetic target value SVa at this device is represented by _{SVa = SV 0 + m (δ} ) · (SV-SV 0) ... (8).

When the control target value SV changes stepwise, the difference δ of (SV−SV ₀ ) is large and δ ₂ ≦ δ (9). Therefore, the membership function is m (δ ) = 0
Next, the SVa = SV ₀ from the equation (8). That is, only the transfer function of the target value filter means 1 determines Is introduced to the deviation calculating means 3 as a second calculation target value. Therefore, in this case, the same response characteristics as those of the conventional device can be obtained.

Thereafter, when the difference δ obtained from the subtraction means 11 becomes smaller than δ ₂ and δ ₁ ≦ δ <δ ₂ (11), the membership function from the membership function setting means 13 ′ becomes 0 <m. (Δ) <1, and from the equation (8), SVa = SV ₀ + m (δ) × (SV−SV ₀ ) (12), and this SVa is used as the second calculation target value by the deviation calculation means 3. Sent out. Therefore, in this case, the difference δ is equal to the difference δ ₂
At this point, the response characteristic becomes faster than the conventional response characteristic as shown in FIG.
Approaching.

Further, when the difference δ obtained from the subtraction means 11 becomes smaller and the relation of 0 ≦ δ <δ ₁ (13) is satisfied, the membership function becomes m (δ) =
1 and, from the equation (8), SVa = SV (14), and the control target value SV is directly sent to the deviation calculating means 3 as the second calculation target value. As a result, the second target value forcibly becomes the control target value SV at time tb when the difference δ ₁ is reached.
Therefore, the setting can be performed in a very short time as compared with the related art.

Therefore, according to the configuration of the embodiment as described above, the first calculation target value SV ₀ of the target value filter means 1 is set to the control target value SV.
When approaching, that is, when the difference between both the target value has reached the predetermined value [delta] ₂ or less, the membership function of the second operation target value SVa from the first operation target value SV ₀ of the target value filter unit 1 employed in The control target value SV is forcibly changed to the control target value SV quickly, so that the target value follow-up time can be greatly reduced without affecting the function of two degrees of freedom, and the performance of this type of two degree of freedom adjustment device is greatly increased. Can be improved, and can be greatly contributed to improvement of plant operation characteristics by being studded throughout the plant.

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 is omitted and the value corresponding to the multiplication value is replaced with the membership function setting means. It is also possible to output from 13 and 13 ′ and add to the adding means 15. Although the PI adjustment 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 scope of the invention.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a two-degree-of-freedom adjusting apparatus that can greatly reduce the response time to a change in a target value as compared with the related art, and greatly contributes to performance improvement.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a two-degree-of-freedom adjusting device according to the present invention, FIG. 2 is a block diagram showing another embodiment of the device of the present invention, and FIG. Response characteristic diagram to target value change for comparing devices, 4th
The figure is a block diagram of the conventional device. 1 Target value filter means 2 Control object 3 Deviation calculation means 4 PI or PID adjustment means 11 Subtraction means 12 Absolute value means 13, 13 'Member Ship function setting means, 14 multiplication means, 15 addition means.

Claims (1)

(57) [Claims] 1. A target value filter means is provided, and at least PI (PI) is calculated by using a deviation between a calculation target value obtained by calculating an introduced control target value by the target value filter means and a control amount from a control target. P: proportional, I: integral) In a two-degree-of-freedom adjusting apparatus for executing an adjustment operation and applying an operation signal obtained by the adjustment operation to the controlled object, a control target value to be introduced to the target value filter means and this target Means for extracting the absolute value of the difference from the first calculation target value or the two target value differences obtained by the calculation of the value filter means, and setting a value of 0 to 1 in advance corresponding to the absolute value difference or the two target value differences. Membership function setting means for setting a membership function to be taken and outputting a membership function corresponding to the absolute value or the difference between the two target values extracted by the means; Multiplying the membership function output from the determining means by the difference between the two target values, and using the obtained multiplied value to correct the first calculation target value and extracting a second calculation target value A two-degree-of-freedom adjustment device, comprising: calculating a deviation from the second calculation target value and a control amount from the control target.