JPH07311601A - Two-degree-of-freedom pid adjusting device - Google Patents

Abstract

PURPOSE:To quicken target value response without influence upon disturbance suppression characteristics. CONSTITUTION:The adjusting device which performs PID adjustment arithmetic by using a target value SV and the feedback controlled variable PV of a controlled system 1 and then adds a disturbance element D to the operation output MV obtained by the arithmetic and applies the result to the controlled system is provided with a target value response improving means 6 which has a response improvement coefficient gamma on the output line of the target value and a controlled variable filter 2 for a leading and a delay element having a leading and a delay time proportional to the integration time of PI adjustment arithmetic provided to the feedback line is separated into a dynamic characteristic transfer function means 11 and a static characteristic transfer function means 12. A subtracting means 13 which subtracts the output of the target value response improving means from the feedback controlled variable is provided and the output of this subtracting means is inputted to the dynamic characteristic transfer function means to make target value response characteristic fast.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-degree-of-freedom PID adjusting device for optimizing both target value tracking characteristics and disturbance suppression characteristics, and particularly to a two-degree-of-freedom PID for realizing speed-up of target value tracking characteristics. Regarding the adjusting device.

[0002]

2. Description of the Related Art This type of PID (P: proportional, I: integral,
D: Differential) regulators have been widely used in all industrial fields since the history of control, and PI can be used in any control system.
It is becoming impossible without the D adjustment device. Thus, the adjusting device which is frequently used cannot optimize the target value tracking characteristic and the disturbance suppressing characteristic, which are its basic functions, at the same time, and these two functions are in a trade-off relationship.

From the standpoint of satisfying both of these functions, a target value filter type two-degree-of-freedom PID adjusting device in which a compensating element is inserted in the target value, and a control amount filter for advancing / delaying elements in the feedback line of the control amount are provided. A loop compensation type two-degree-of-freedom PID adjusting device incorporating the compensating element has been developed.

In particular, the latter loop compensation type two-degree-of-freedom PID
The adjusting device inserts a control amount filter of a lead / lag element whose lead / lag time is a time proportional to the integration time of the PI adjustment calculation into the feedback line of the control amount, and simultaneously sets the target value tracking characteristic and the disturbance suppression characteristic. It is optimized and is said to have better controllability than the target value filter type.

Hereinafter, a conventional loop-compensated two-degree-of-freedom PID
The adjusting device will be described with reference to FIG. In the figure, 51 is a controlled object, 52 is a controlled variable filter inserted in the controlled variable feedback loop of the controlled object 51, and its typical transfer function F (s) is F (s) = (1 + αβT _I・ S) / (1 + βT _I・ s) ・ ・ ・ (1) However, α: 0 to 3, β: 0 to 1, T _I : integration time, s: Laplace operator. 53 is the target value SV
deviation E between (s) and output Y ₀ (s) of controlled variable filter 52
(s) is a deviation calculating means, 54 is a PI adjusting means for executing a PI calculation so that the deviation E (s) is zero, and its transfer function C (s) is C (s) = K _p {1 + 1 / (T _I · s)} (2) K _p is a proportional gain and T _I is an integration time. 55 is a disturbance D on the output MV (s) of the PI adjusting means 54.
It is an adding means for adding (s) and applying it to the controlled object 51.

The compensation element of the control amount filter 52 as described above is used because the input and the output are equal in the steady state.
If the initial value of the output response when the unit step signal is input is α and the attenuation characteristic is β, these α and β can be set independently of each other. By the way, when the response formula of the control amount Y (s) of the feedback control system shown in FIG.

[0007]

[Equation 1] Can be expressed as Furthermore, in order to investigate the operation of the response formula in detail, C (s) = K _p {1 + 1 / (T _I · s)}, F (s) = (1
By substituting the relationship of + αβT _I · s) / (1 + βT _I · s),

[0008]

[Equation 2] become that way. Therefore, from the above equation, the two degrees of freedom can be realized by adjusting the parameters α and β, and the optimum values thereof are α = 2.5 and β = 0.54.

Therefore, although the feedback control system shown in FIG. 6 achieves two degrees of freedom from the response equation (4), it still has improved controllability when the limit of controllability is considered to be extremely high. There is room to do it. That is, the adjustment operation of the part related to the response of the target value SV (s) of the equation (4), that is, the numerator part of the first term is only the PI operation,
This is because if the differential (D) operation can be performed here, the response characteristic of tracking the target value can be speeded up without affecting the disturbance suppression characteristic shown in the second term of the equation (4).

[0010]

Therefore, as is apparent from the above description, the loop compensation type two-degree-of-freedom PID adjusting device, which is the basic technology of the control system, has a substantial response characteristic due to the two-degree-of-freedom. Can be improved.

However, considering that 90% or more of the above adjusting devices are used in the plant control system, it is necessary to further improve the controllability, and the flexibility and the quality are high. It will also be useful for the production of control devices. Therefore, further improvement in control performance is required for this type of adjusting device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a two-degree-of-freedom PID adjusting device for speeding up the control response characteristic according to the change of the target value.
Another object of the present invention is to provide a two-degree-of-freedom PID adjusting device that improves the target value tracking characteristic without affecting the disturbance suppression characteristic while maintaining the conventional loop-compensation type two-degree-of-freedom control. It is in.

[0013]

In order to solve the above-mentioned problems, the invention corresponding to claim 1 is such that the target value and the feedback control amount of the controlled object are advanced / extended with a time proportional to the integration time of the PI adjustment calculation. PI or P based on the deviation from the adjustment control amount obtained through the control amount filter of the delay element
A target value response improving means for executing an ID adjustment calculation, adding a disturbance element to an operation output obtained by this calculation, and applying the result to a controlled object, the target value response improving means for multiplying the target value by a response improvement coefficient, and outputting the result. It is a subtracting means for subtracting the output of the target value response improving means from the feedback control amount and outputting it, and a two-degree-of-freedom PID adjusting device for inputting the signal obtained from the subtracting means to the control amount filter.

Next, the invention according to claim 2 is for adjusting the feedback control amount of the target value and the controlled object, which is obtained through a control amount filter of lead / lag elements having a time proportional to the integration time of the PI adjustment calculation. A static characteristic transfer function means and a dynamic characteristic transfer function means are provided in an adjusting device that executes a PI or PID adjustment calculation based on a deviation from a control amount and adds a disturbance element to an operation output obtained by this calculation and applies the result to a control target. And a control amount filter, a target value response improving means for multiplying the target value by a response improving coefficient and outputting the result, and a control value filter for subtracting the output of the target value response improving means from the feedback control amount. And a subtraction means for inputting to the characteristic transfer function means, and by varying the response improvement coefficient, a proportional gain and a derivative of the response characteristic with respect to the change of the target value. A two-degree-of-freedom PID adjustment device for varying the in.

The dynamic characteristic transfer function means of the controlled variable filter is (1) {(1 + αβT _I · s) / (1 + βT _I ·
s)}-1 (2) (α-1) βT _I · s / (1 + βT _I · s) (3) (α-1) {1-1 / (1 + βT _I · s)} It has a function. However, in the above equation, α and β are two-degree-of-freedom parameters, T _I is an integration time, and s is a Laplace operator.

[0016]

Therefore, according to the inventions corresponding to claims 1 and 2, when the target value changes, the signal obtained by multiplying the changed target value by the variable response improvement coefficient is obtained by taking the above means. This is introduced into the control amount filter of the advance / delay element that makes the time proportional to the integration time of the PI adjustment calculation the advance / delay time. This control amount filter is separated into a dynamic characteristic transfer function means and a static characteristic transfer function means, and after subtracting the multiplication signal from the feedback control amount of the controlled object, it is introduced into the dynamic characteristic transfer function means, and the dynamic characteristic transfer function means. If the output of the function means and the output of the static characteristic transfer function means are added and introduced into the deviation calculating means of the control system, only the proportional gain and the differential gain of the response characteristic with respect to the change of the target value change, and the disturbance It is possible to speed up the target value response while the suppression characteristic remains unchanged.

Furthermore, the invention corresponding to claim 3 is the dynamic characteristic transfer function means described in the invention corresponding to claim 2, wherein (1) {(1 + αβT _I · s) / (1 + βT _I ·
s)}-1 (2) (α-1) βT _I · s / (1 + βT _I · s) (3) (α−1) {1-1 / (1 + βT _I · s)} If it is used, the differential operation can be utilized for the change of the target value without affecting the disturbance suppression characteristic and the response characteristic of the target value tracking can be improved only by using the coefficient multiplication function and the addition / subtraction function. .

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a two-degree-of-freedom PID according to the present invention.
It is a block diagram which shows the 1st Example of an adjustment device, Comprising: It is one structural example of invention corresponding to Claims 1 and 2. FIG.

In FIG. 1, reference numeral 1 denotes a controlled object such as various plants and control systems, and a controlled variable filter 2 is provided in the feedback line of the controlled variable PV (s) obtained from the controlled object 1. The adjustment control amount Y ₀₁ (s) after passing through the amount filter 2 is sent to the deviation calculating means 3. The deviation calculating means 3 obtains a deviation E (s) between the target value SV (s) and the adjustment control amount Y ₀₁ (s) and introduces it into the PI adjusting means 4. In the PI adjusting means 4, the PI adjusting operation is executed so that the deviation E (s) becomes zero to obtain the operation output MV (s). Reference numeral 5 is an addition means for adding the disturbance D (s) to the operation output MV (s) and applying it to the controlled object 1.

Further, a target value response improving means 6 having a variable response improving coefficient γ on the output line of the target value SV (s).
Is connected, and the output of the target value response improving means 6 is introduced to the input side of the controlled variable filter 2.

The controlled variable filter 2 advances / decreases a time proportional to the integration time of the PI adjustment calculation as a advance / delay time.
Although it is composed of a delay element, it is separated into a dynamic characteristic transfer function means 11 and a static characteristic transfer function means 12 in order to have a differential operation function, while the control obtained from the controlled object 1 is provided on the input side of the dynamic characteristic transfer function means 11. A subtracting means 13 for subtracting the output of the target value response improving means 6 from the quantity PV (s) is provided, and the output of the dynamic characteristic transfer function means 11 and the output of the static characteristic transfer function means 12 are added to adjust the control amount for adjustment. The configuration is such that an adding means 14 for determining Y ₀₁ (s) and introducing it into the deviation calculating means 3 is provided.

Therefore, according to the configuration of the above embodiment, the controlled variable PV (s) obtained from the controlled object 1 is introduced into the control filter 2, but is branched into two at the input side of this control filter 2. On the other hand, on the one branch side, the controlled variable PV (s) is guided to the addition means 14 through the static characteristic transfer function means 12 having the transfer function "1", and on the other branched side, the controlled variable PV (s) and the target value SV. Signal γ · SV obtained by multiplying (s) by the response improvement coefficient γ
(s) and are introduced into the subtraction means 13, where the subtraction operation signal {PV (s) -γ · SV (s)} is taken out and the transfer function F
(s) -1 is introduced into the adding means 14 through the dynamic characteristic transfer function means 11. In the adding means 14, the output of the dynamic characteristic transfer function means 11 and the output of the static characteristic transfer function means 12 are added and synthesized, and the adjustment control amount Y ₀₁ (s) is taken out and introduced into the deviation calculating means 3.

[0023] The deviation calculating means 3, the target value SV (s) and adjusting the control amount Y ₀₁ (s) deviation between the E (s) = SV (s ) -Y 01
(s) is calculated, and the obtained deviation E (s) is transferred to the transfer function C (s) =
PI with Kp {1 + 1 / (T _I · s) (Kp: proportional gain, T _I : integration time, s: Laplace operator)
It is applied to the adjusting means 4, and here the operation output MV (s) is taken out by the PI adjusting operation. Furthermore, this operation output MV
(s) is added and combined with the disturbance D (s) by the adding means 5 and applied to the controlled object 1, so that the deviation becomes zero, that is, the target value SV (s) = the control amount for adjustment Y ₀₁ (s). To control.

Therefore, according to the above apparatus, when the target value SV (s) changes stepwise as shown in FIG. 2A, the response improvement coefficient γ of the target value response improving means 6 is 0 to 0. If it is set between 1, the target value response improving means 6
Then, a signal as shown in FIG. 7B is output from the same, and when this signal passes through the subtracting means 13 and the dynamic characteristic transfer function means 11, a differential component showing a falling in the negative direction appears as shown in FIG. It is introduced into the deviation calculating means 3 through the adding means 14. Since the output of the dynamic characteristic transfer function means 11 is introduced into the deviation calculating means 3, it is inverted as shown in FIG. 6 (d), and the target value SV (s) is further added to this output, so that FIG. ), The output of the dynamic characteristic transfer function means 11 is superimposed on the target value SV (s), and it becomes possible to take out a deviation that sharply decreases at a so-called large rise, which has no influence on the disturbance suppression characteristic. It is possible to speed up the response characteristic of following the target value.

Next, FIG. 3 is a constitutional view showing a second embodiment of the two-degree-of-freedom PID adjusting device, which is an example of constitution of the invention corresponding to claim 3. In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

In this embodiment, the controlled variable filter 2 shown in FIG. 1 is embodied, and the integration time T of the PI adjusting means 4 is set.
Transfer function F (s) with lead / lag time proportional to _I ,
That is, by subtracting the output of the subtraction means 13 from the transfer function unit 21 having F (s) = (1 + αβT _I · s) / (1 + βT _I · s) (5) and the output of this transfer function unit 21 {(1 + αβT _I · s) / (1 + βT _I · s) −1} = F (s) −1 (6) The dynamic characteristic transfer function means 11A including the subtracting means 22 for outputting a signal is further provided. In this configuration, the transfer function of the static characteristic transfer function means 12 is "1".

Further, FIG. 4 is a constitutional view showing a third embodiment of the two-degree-of-freedom PID adjusting device, which is one constitutional example of the invention corresponding to claim 3. In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

In this embodiment, when the transfer function of the dynamic characteristic transfer function means 11A shown in FIG. 3 is modified, {F (s) -1} = {(1 + αβT _I · s) / (1 + βT _I · s) −1 } = {(Α-1) βT _I · s} / (1 + βT _I · s) (7) Therefore, it can be realized by using the transfer function of the equation (7) for the dynamic characteristic transfer function means 22 of the controlled variable filter 2.

Further, FIG. 5 is a constitutional view showing a fourth embodiment of the two-degree-of-freedom PID adjusting device, which is one constitutional example of the invention corresponding to claim 3. In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

In this embodiment, when the transfer function {F (s) -1} of the dynamic characteristic transfer function means 22 of FIG. 4 is modified, {F (s) -1} = (α-1) {1-1 / (1 + βT _I · s)} (8)

Therefore, the transfer function of the equation (8) can be used for the dynamic characteristic transfer function means 31 of the controlled variable filter 2. Next, in order to clarify the effect of the device of the present invention,
First, when the response expression of the control amount in FIG. 1 is obtained,

[0032]

[Equation 3] It is represented by.

Therefore, this equation (9) and the conventional device (3) are used.
Comparing with the equation, in the above equation (9), a portion related to the response improvement coefficient γ is added to the term of the response to the target value SV (s) in the first term of the response equation. When = 0, the configuration is the same as that of the conventional device, and γ =
By varying the value from 0 or more (excluding 0) to 1, the response characteristic of the target value SV (s) can be speeded up.

Further, since it becomes clear when the transfer function of the controlled variable filter 2 is expressed by a specific mathematical expression, the response expression is obtained in this case. In the examples of FIGS. 3 to 5, the transfer function F (s) of the controlled variable filter 2 is F (s) = (1 + αβT
_I · s) / (1 + βT _I · s), which is a modification of only the equation of the dynamic characteristic transfer function means. Therefore, the response formulas in FIGS. 3 to 5 are exactly the same, and the easiness of understanding the formula and the difficulty level of the formula are different when the device is realized. That is, the response expressions of FIGS. 3 to 5 are

[0035]

[Equation 4] Can be expressed as

Therefore, comparing equation (10) representing the control response of the device of the present invention with equation (4) representing the control response of the conventional device, the first term representing the control response to the change of the target value SV (s). The term relating to the response improvement coefficient γ of the numerator of is added. Therefore, if γ = 0 in the equation (10), it becomes exactly the same as the equation (4). On the other hand, when γ = 0 or more (excluding 0) to 1 in the equation (10), the numerator of the first item of the equation (10) is observed, and a differential action is added as the proportional gain increases. As a result, the differential gain becomes large, and the control response speed accompanying a change in the target value can be improved to the limit.

Therefore, according to the device of the present invention, the control amount filter 2 of the advance / delay element in which the time proportional to the integration time inserted in the feedback line of the control amount is the advance / delay time is used as the static characteristic transfer function means. 12 and the dynamic characteristic transfer function means 11, 11A, 21, 31 are separated, and the target value SV (s) is obtained from the control amount PV (s) which is an input signal of the dynamic characteristic transfer function means 11, 11A, 21, 31. If the configuration is such that the signal proportional to is subtracted, the original differential configuration is not provided,
By combining the PI adjusting means 4 and the controlled variable filter 2,
It is possible to achieve a complete two-degree-of-freedom of the PID3 term that can generate a differential operation and speed up the response to the change of the target value to the limit, and further improve the characteristics as compared with the conventional two-degree-of-freedom PID.

Further, there are few additional functions for this improvement, there is no addition of a temporal element that increases the load of the adjustment calculation, and it can be achieved only by adding the coefficient multiplication operation and the addition / subtraction operation, which is widely used industrially. This is a great advantage.

In the above embodiment, the dynamic characteristic transfer function shown in FIG. 1 is expanded to the three concrete examples shown in FIGS. 3 to 5, but from the same point of view, it is expanded to other transfer function formulas to have a concrete structure. It is also possible to do so. In addition, the present invention can be modified in various ways without departing from the scope of the invention.

[0040]

As described above, according to the present invention, the proportional gain and the differential gain of the response characteristic can be changed with respect to the change of the target value, and the response of the target value can be made quick without affecting the disturbance suppression characteristic. Can be achieved. Moreover, the control performance can be enhanced with a simple configuration.

[Brief description of drawings]

1 is a two-degree-of-freedom P that is an invention corresponding to claims 1 and 2;
The block diagram which shows one Example of an ID adjustment device.

FIG. 2 is a timing chart showing operation waveforms of a main part of the device of the present invention.

FIG. 3 is a two-degree-of-freedom PID that is an invention corresponding to claim 3;
The block diagram which shows one Example of an adjustment device.

FIG. 4 is a two-degree-of-freedom PID that is an invention corresponding to claim 3;
The block diagram which shows the other Example of an adjustment device.

FIG. 5 is a configuration diagram showing another embodiment of a two-degree-of-freedom PID adjustment device that is the invention according to claim 3;

FIG. 6 is a configuration diagram of a conventional two-degree-of-freedom PID adjustment device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Control object, 2 ... Control amount filter, 3 ... Deviation calculating means, 4 ... PI adjusting means, 11, 11A, 21, 31 ... Dynamic characteristic transfer function means, 12 ... Static characteristic transfer function means, 13 ...
Subtracting means, 14 ... Addition means.

Claims (3)

[Claims] 1. A PI or PI based on a deviation between a target value and a feedback control amount of a controlled object with an adjustment control amount obtained through a control amount filter of a lead / lag element having a time proportional to an integration time of PI adjustment calculation. A target value response improving means for executing a PID adjustment calculation, adding a disturbance element to an operation output obtained by this calculation, and applying the result to a controlled object; Subtraction means for subtracting and outputting the output of the target value response improving means from the feedback control amount,
A two-degree-of-freedom PID adjusting device characterized in that a signal obtained from the subtracting means is input to the controlled variable filter. 2. A PI or a control value based on the deviation between the target value and the feedback control amount of the controlled object, which is obtained through a control amount filter of lead / lag elements having a time proportional to the integration time of the PI adjustment calculation. In a control device for executing a PID adjustment calculation and applying a disturbance element to the operation output obtained by this calculation and applying it to a control target, a control amount filter formed by separating static characteristic transfer function means and dynamic characteristic transfer function means. , A target value response improving means for multiplying the output of the target value by a response improving coefficient and outputting the result, and a subtraction for subtracting the output of the target value response improving means from the feedback control amount and inputting it to the dynamic characteristic transfer function means Means for changing the response improvement coefficient to change the proportional gain and the differential gain of the response characteristic with respect to the change of the target value. 2 DOF PID adjustment device according to symptoms. 3. The two-degree-of-freedom PID adjusting device according to claim 2, wherein the dynamic characteristic transfer function means of the controlled variable filter has one of the following transfer functions. (1) {(1 + αβT _I・ s) / (1 + βT _I・ s
s)}-1 (2) (α-1) βT _I · s / (1 + βT _I · s) (3) (α-1) {1-1 / (1 + βT _I · s)} where α in the above equation , Β are two-degree-of-freedom parameters,
T _I is the integration time and s is the Laplace operator.