JPH03202902A - Controller for two degrees of freedom - Google Patents

Abstract

PURPOSE:To generate a derivative action as a whole and to set P and D into two degrees of freedom by combining a PI adjustment means and a target value filter means having two primary delay elements in the P(proportion)/I (integration)/D(derivative) adjustment device of a two degrees of freedom-form. CONSTITUTION:The target value filter means 10 has a coefficient multiplication means 11 multiplying the targe value SV by the two degrees of freedom coeffi cient of a proportional gain Kp and the two degrees of freedom coefficient of derivative time, and a derivative term sharing means sharing the derivative term of the tartget value SV and a controlled variable PV by subtracting the controlled variable being the object of control from the output of the coefficient multiplication means 11 and setting it to pass through the primary delay elements. Thus, time elements can be reduced and D can be made into two degrees of freedom.

Description

Detailed Description of the Invention [Objective of the Invention (Industrial Application Field) The present invention relates to a two-degree-of-freedom P (proportional) I (integral) D (differential) adjusting device, and particularly relates to a P1m node means and a P1m node means. The present invention relates to a two-degree-of-freedom adjustment device that generates a differential operation as a whole by combining target value filter means having two first-order lag elements, and realizes two degrees of freedom in P and D.

(Prior Art) PI or PID regulators have been widely used in all industrial fields since the beginning of process control, and it has become impossible to do without PID regulators in the instrumentation field.

Various adjustment methods have been proposed in the past, and in the current 71: digital adjustment calculation method has been adopted in place of the analog method, but the throne of the PID adjustment device has not changed in the slightest, and it is important for plant operation. It forms the basis of control.

The basic formula of such a PID, clause 1, is expressed as follows. However, MV (s) is the operation signal, E (s)
is the deviation, Kr is the proportional gain, TI is the integral time, To is the differential time, S is the Laplace operator, and (1/η) is the differential gain. This equation (1) defines the deviation signal E (s) as PID,
This is an 11-section calculation and is called deviation PID adjustment.

Usually, the PID used professionally; i13 clause calculation method is:
The target value SV often changes in steps due to high-mix, low-volume production and a wide range of user requests. In this case, if the D (differential) operation is working, the deviation E (s) will expand, and the PID will increase accordingly. Operation signal M which is the adjustment calculation output
V(s) causes a sudden change. As a result, the process value (measured value)
Perform a differential operation on Pv only. The so-called "measured value differential preceding type PIDJ!J clause method" is adopted.

This measured value differential leading form p r D: J3ffi method is
In order to prevent steep fluctuations in deviations and their expansion, this is a method in which a differential term is applied only to the process value PV to focus the fluctuations in the target value, and can be expressed by the calculation formula (2) below. .

However, in the above formula, P V (s) is a process value.

However, the PID adjustment described above is a PID with one degree of freedom.
This is called an adjustment calculation method and is a so-called one-degree-of-freedom method in which only one set of PID parameters can be set, and it is naturally impossible to optimize both the disturbance suppression characteristic and the target value tracking characteristic at the same time.

Generally, in a control system using PI or PID control, it is necessary to satisfy both the disturbance suppression characteristics and the target value tracking characteristics. The former disturbance suppression characteristic is how to optimally suppress the influence of disturbance when the disturbance changes, and the latter target value tracking characteristic is how the process value optimally follows the target value when the target value is changed. This shows whether the In a normal PI or PID control system, the PI or PID parameter value that optimally suppresses the influence of disturbance changes and the PI or PID parameter value that optimally follows target value changes are significantly different, and the characteristics of both are very different. l1i
l n! 7 cannot be optimized, and there is a trade-off between them. In other words, if the PID parameter value is set to optimally suppress the influence of disturbance changes, the target value tracking characteristic will become oscillatory, and conversely, if the PID parameter value is set to optimally follow the target value change, the disturbance will be suppressed. The characteristics become very weak.

Therefore, in this type of PID adjustment device, it has been desired to develop a technology that simultaneously optimizes the disturbance suppression characteristics and the target value tracking characteristics.

On the other hand, in 1963, I5sac, M.

Two degrees of freedom PI or PID algorithm (TwODcgrccs P 1 (or P I D ) A IgorlLha 2 or less, 2 DO
The basic concept of FPID (collectively referred to as FPID) was announced, and in recent years, 2DOF PID has been developed in Japan based on the above basic concept, and is greatly contributing to the advancement of plant operation control.

FIG. 6 is a diagram showing a block configuration of a conventional 2DOF PI adjustment device. This device is a measurement value differential leading type PI
This configuration has a target value filter means H(s) added to the input end of the D adjustment device. This target value filter means H(s)1
is a lead/lag element 1□ that leads or lags the target value SV, a serially connected incomplete differential element 12.13 that delays the differential operation with respect to the target value SV, and the lead/lag element $1. The output Svo from the target value filter means H(S)1 is sent to the deviation calculation means 2 of the measured value differential type PID. supply

This measurement') JA value differential leading type PID is calculated by the deviation calculating means 2.
The output SV of the target value filter means H(s)1.

After finding the deviation E between and the controlled variable PV from the controlled object 3,
This deviation E is introduced into the nonlinear means 4, and here the insensitivity jl
) processing, deviation squaring processing, directionality processing, and other non-linear processing, and is guided to the PI adjustment means 5, where the PI adjustment calculation on the first stage side of the equation (2) is performed. Then, this PI adjustment calculation means 5
The PI adjustment calculation output obtained in is supplied to the subtracting means 6.

In addition, the control amount Pv from the controlled object 3 is determined by the incomplete differential element 7.
Here, an incomplete differential operation is performed on the latter side of the equation (2), and the obtained incomplete differential operation output is introduced into the subtracting means 6. A so-called differential bypass is performed. This subtraction means 6
Then, the incomplete differential calculation output is calculated from the PI adjustment calculation output, and the obtained signal is led to the addition means 8 as the operation signal MV, where it is added and combined with the disturbance signal and applied to the controlled object 3. , target value 5Vo-control fiPV.

Therefore, according to the above configuration, the disturbance suppression control algorithm Co(s) is expressed as follows, while the anti-disturbance control algorithm C5(s)
) is represented by . In this equation, α is a two-degree-of-freedom coefficient for the proportional gain, and γ0 is a two-degree-of-freedom coefficient for the integral time. Based on the above equation (3), T+ and To are set to optimize the disturbance suppression characteristic. After determining, the two-degree-of-freedom coefficients α and γ that optimize the target value tracking characteristic are further determined based on the above equation (4). , it is possible to achieve two degrees of freedom.

(Problems to be Solved by the Invention) However, although the 2DOF PI adjustment device described above has various features, it also has the following defects.

■ Originally two degrees of freedom coefficients α and γ. must have a relationship with each other, but in the conventional control method, α and γ must have a relationship with each other, as shown in equation (4). are completely independent, so when the two-degree-of-freedom coefficient α of the proportional gain is changed, γ is changed separately accordingly. It also takes a lot of time to make adjustments.

■Also, in this type of instrumentation plant, tens to thousands of control loops are often used, and each of these control loops has four time elements ( Lead/lag element 11. Imperfect differentiator 1□
, 1. ．． 7), the cost becomes very high, the load on the entire system increases, and there are problems in that it is not possible to achieve high-speed data processing and low-capacity data processing.

(2) Furthermore, in actual plant control, nonlinear processing is often performed on deviations, but this nonlinear processing cannot be easily, accurately, and freely created.

In other words, in actual plant control, the controlled object 3
Depending on the characteristics of px:Ar
A nonlinear means 4 is provided on the input side of the t1 means 5, and nonlinear processing such as insensitivity 1), squared deviation, directionality, and gap is used for the deviation signal E, but the incomplete differential element 7 is Since it is bypassed to the output side of the tuning ff1f-stage 5, it is not subject to nonlinear processing, and therefore nonlinear processing cannot be performed accurately, resulting in a problem of reduced controllability.

In particular, in the future, plant operation control systems will increasingly be required to have higher precision, faster response, optimization, and safety, and in order to fully meet these demands, fundamental PID, which is often used in plants, is required. 2 DOF PID
Therefore, it is necessary to eliminate the above-mentioned defects.

The present invention has been made in view of the above-mentioned circumstances, and when the two-degree-of-freedom coefficient α of the proportional gain is changed, the gain of the differential term can also be changed automatically, and the load can be reduced using fewer time elements. An object of the present invention is to provide a two-degree-of-freedom adjustment device that enables high-speed processing.

Furthermore, another object of the present invention is to provide a two-degree-of-freedom adjustment device that can accurately, easily, and freely perform nonlinear processing including differential operation to improve controllability.

[Structure of the invention] (Means for solving the problem) In order to solve the above problem, the invention corresponding to claim 1 has the following features:
P(
In the adjustment device in which a proportional) and I (integral) adjustment means performs a P1 adjustment calculation, and a disturbance signal is added to an operation signal that is the obtained adjustment calculation output and applied to the controlled object, the target value filter means a coefficient multiplier for multiplying the target value by a two-degree-of-freedom coefficient for the proportional gain and a two-degree-of-freedom coefficient for the differential time, and subtracting the controlled variable of the controlled object from the output of the coefficient multiplier and passing it through a first-order lag element. By this, the configuration is provided with a differential term sharing means for sharing the differential term of the target value and the control amount, and realizes two degrees of freedom of the differential characteristic 181.

Next, the invention corresponding to claim 2 is the invention corresponding to claim 1, further comprising: gain coefficient multiplication means for multiplying the target value by a two-degree-of-freedom coefficient of the proportional gain; and gain coefficient multiplication means from the target value. 1 to the subtracted output obtained by subtracting the output of
Added two-degree-of-freedom means for proportional gain consisting of a first first-order lag element that provides a second-order lag, and means for adding the output of the first first-order lag element to the output of the gain coefficient multiplication means. It is.

Furthermore, the invention corresponding to claim 3 provides a nonlinear means between the deviation calculation means and the P I :14111 means when the differential term of the control aX is taken into the target value filter means,
This configuration also performs nonlinear processing on differential components.

(Function) Therefore, in the invention of claim 112, by taking the above measures, the lead/lag element and the differential time for making the proportional gain in the target value filter means have two degrees of freedom. All incomplete differential elements for obtaining degrees of freedom are decomposed into static elements proportional to human power and dynamic elements that change with a first-order lag in relation to human power, and the first 2 first-order delay elements are provided, and the differential term of the target value and control amount is set as the first-order delay element. shared by the second first-order lag element, 1,
While sharing the target value and the first-order delay of the gain h1 change of the controlled variable at the time of iJ, two degrees of freedom of P and D are realized with a simple configuration.

Furthermore, in the invention of claim 3, not only the differential term of the target value but also the differential term of the control [1] is taken into the target value filter means and passed through the first-order lag element, so that the nonlinear processing by the differential operation can be appropriately performed. It is something to do.

(:, ljk example) Hereinafter, a major example of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of a 2DOF PID adjustment device of the present invention. In this device, the same parts as those in FIG. 6 are given the same reference numeral 7:), and detailed explanation will be omitted. This 2DOF PID adjustment device includes a target value filter means 1o that receives the target value SV and performs arithmetic processing to obtain a proportional gain and two degrees of freedom regarding the differential time TO.
After receiving the target value filter output Svo obtained from the target value filter means 20 and the control amount Pv, the deviation calculation means 2 calculates the deviation E-3Vo-PV, and then calculates the deviation E by the non-linear means 4 as necessary. A PI algorithm execution section performs nonlinear processing and guides it to the PI adjustment means 5, and performs a PI adjustment calculation here to obtain the operation signal MV, and an addition means 8 adds the operation signal MV obtained by this PI algorithm execution section. Adding the disturbance signal and applying it to the controlled object 3,
5v-svo-pv.

The target value filter means 10 realizes two degrees of freedom for the proportional gain and two degrees of freedom for the differentiation time, and when achieving these two degrees of freedom, the differentiation of the incomplete differentiator 7 that takes a conventional bypass configuration is achieved. The term is taken into the target value filter means 10, and the controlled variable.

Differential of target value, proportional gain of target value, 1 of differential time
In order to realize the practical use of "second delay, etc.", the following configuration was adopted.

First, a two-degree-of-freedom configuration of the proportional gain will be described. l
:I has a gain coefficient multiplication means 11 which multiplies the standard value SV by a proportional gain 2 liberalization coefficient α, and the output obtained by multiplying the coefficient α here is sent to the addition means 12 and the subtraction means 13. This subtraction means 13 subtracts the output α·SV of the gain coefficient multiplication means 11 from the target value SV, and the obtained subtraction output is obtained by subtracting means 14, first-order lag element 15 and addition means 16.
The output of the adding means 16 is added and synthesized by the adding means 12 to the output of the gain coefficient multiplication means 11, thereby realizing two degrees of freedom of the proportional gain.

Next, a configuration in which the differential time is given a 2a degree of freedom will be described. front 6
The gain coefficient multiplication output of the self-gain coefficient multiplication means 11 is guided to the interval coefficient multiplication means 17, which is configured by setting a two-degree-of-freedom coefficient γ of the differential time, and here, the gain coefficient multiplication output is multiplied by the two-degree-of-freedom coefficient γ of the differential time. γ is multiplied, and the obtained output of the time coefficient multiplication means 17 is introduced into the subtraction means 18. This subtraction means 1
In step 8, the control 14 P V of the controlled object 3 is subtracted from the output of the time coefficient multiplication means 17 and then introduced into the division means 19.

The output of one dividing means is branched into two, one of which is directly introduced into the subtracting means 20, and the other is sent to the subtracting means 21 via the first-order delay element 21, where it is sent to the subtracting means 21 from the previous dividing means 19.
The output of the first-order lag element 21 is subtracted from the output of . Then, the subtracted output of the subtracting means 20 is branched into two branches, one of which is input directly to the adding means 16, and the other is subtracted by the subtracting means 14 and then guided to the adding means 16 via the first-order delay element 15.

Here, the output of the first-order lag element 15 and the output of the subtracting means 20 are added and combined, and this summed value is finally added to the output of the gain coefficient multiplication means 11 in the adding means 12 to obtain a target value. Filter output SV.

is obtained and introduced into the deviation calculation means 2.

Next, the reason why the configuration of the target value filter means 10 as described above is adopted will be explained. When the lead/lag element 11 (FIG. 2a) shown in FIG. 6, which is a conventional example, is equivalently converted, it has a configuration as shown in FIG. 2(b). That is, the lead/lag element II is expressed as (1+α·T1·s)/(1,+T+·S), but this equation can be replaced as in equation (5).

(5) Therefore, if this equation (5) is expressed as an equivalent functional block, it becomes as shown in FIG. 2(b).

Next, the incomplete differential element 13 shown in Fig. 6 (Fig. 3 a)
is expressed as (T I ·s)/(1+T+ ·S), but when this formula is transformed, it becomes...(7). Therefore, if this equation is expressed as a functional block, it will become as shown in FIG. 4(b).

Therefore, when the functional blocks shown in FIGS. 2 to 4 are applied to the target value filter means 10, the configuration shown in FIG. 1 is obtained, and the disturbance control algorithm Co(s
) becomes . Therefore, if this equation is expressed as a functional block, it will be as shown in FIG. 3(b). Therefore, as is clear from FIGS. 2 and 3, the primary lag element 15 can be shared.

Next, the incomplete differential element 7 shown in fiI6 (Figure 4a)
is expressed as (To-s)/(1+η・TD-8),
This incomplete differential requires: A7 is transformed, and on the other hand, the target value control algorithm C5v(S) is: As a result, as is clear from these equations (8) and (9), when the two-degree-of-freedom coefficient α of the proportional gain is changed, the proportional gain of the disturbance control algorithm remains unchanged, The proportional gain relative to the target value can be changed by 1...α, and on the other hand, when the two-degree-of-freedom coefficient γ of the differential time is changed, the differential time of the disturbance control algorithm remains the same, but only the differential time relative to the target value is changed. In other words, it is possible to realize complete two degrees of freedom for P and D.

Therefore, according to the embodiment described above, the target value and the controlled variable are passed through the dividing means 19 and the first-order delay means 21 to share the differential term of the target value and the controlled variable, and the conventional lead/lag element is 1 and incomplete differential element 1. By sharing the first-order delay in the first-order delay element 15, the conventional four
It is possible to reduce the time element of pI to 2, which is half of that, which reduces costs, reduces the load on the control system, increases speed, and reduces capacity, and also reduces the number of time elements. It is possible to achieve complete two degrees of freedom for P and D while reducing the amount by half.

Further, since the two-degree-of-freedom coefficient α of the proportional gain and the two-degree-of-freedom coefficient γ of the differential time are set independently, the work of setting the coefficients is very easy.

Furthermore, when the two-degree-of-freedom coefficient α of the proportional gain is changed, the gain of the differential term is also automatically corrected as shown in equation (9), making adjustment of the coefficient very simple.

Furthermore, by removing the conventional incomplete differential element 7 that was bypassed after the PI# node means and taking the differential term of the controlled variable into the target value filter means 10, the differential component can be accurately nonlinearly processed. I can do it.

Therefore, the device of the present invention can completely transition to the era of two degrees of freedom, and can make a significant contribution to various industrial fields.

In the above embodiment, the output of the gain coefficient multiplication means 11 is multiplied by the two-degree-of-freedom coefficient γ of the differential time, but for example, as shown in FIG. A configuration in which the two-degree-of-freedom coefficient γ is directly multiplied may also be used. Therefore, according to such a configuration, the equation corresponding to the above equation (8) is exactly the same, and the equation corresponding to equation (9) is as follows. When changing the coefficient α,
The difference is that the gain of the differential term is no longer automatically corrected.

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 the following various effects.

First, in the invention of claim 1, it is possible to obtain the phase ratio of the differential term between the target value and the controlled amount, thereby reducing the time element and realizing two degrees of freedom in D. .

Next, in the invention of claim 2, not only the differential term between the target value and the controlled variable is shared, but also the first-order lag of the conventional lead/lag element and the incomplete differential element is shared by the first-order lag element. I can do it,
As a result, it is possible to reduce the time factor by half, reduce costs, reduce the load, and speed up processing, and moreover, it is possible to achieve complete two degrees of freedom in P and D. Furthermore, by changing the two-degree-of-freedom coefficient of the proportional gain, the gain of the differential term can be automatically corrected, and the :J8 adjustment of the coefficient can be simplified.

Furthermore, the invention according to claim 3 can perform nonlinear processing not only for P■ but also for D, and can sufficiently deal with various types of control.

[Brief explanation of drawings]

1 to 4 are shown to explain an embodiment of a two-degree-of-freedom adjusting device according to the present invention, and FIG. 1 is a functional block diagram of the two-degree-of-freedom adjusting device, and FIG. FIG. 5 is a functional block diagram showing an equivalent replacement of time elements, FIG. 5 is a functional block diagram of a target value filter means showing a modification of the device of the present invention, and FIG. 6 is a functional block diagram of a conventional device. 2...8 stages of deviation operators, 3...Controlled object, 4...
Nonlinear means, 5... PI adjustment means, 8... Adding means, 10... Target value filtering means, 11... Gain coefficient multiplication means, 12.16... Adding means, 13, 14,
18.20... Subtraction means, 15... First-order lag element,
17.17a... Intercostal coefficient multiplication means, one... Division means, 21... First-order lag element. Figure 2

Claims (3)

[Claims] (1) The P (proportional) and I (integral) adjusting means performs PI adjustment calculation in response to the deviation between the target value filter output obtained through the target value filter means and the controlled variable of the controlled object, and the target value is obtained. In the adjustment device that applies an operation signal that is an adjustment calculation output to the controlled object, the target value filter means multiplies the target value by a two-degree-of-freedom coefficient of a proportional gain and a two-degree-of-freedom coefficient of a differential time. a coefficient multiplication means, and subtracting the control amount of the controlled object from the output of the coefficient multiplication means;
A two-degree-of-freedom adjustment device characterized by comprising a differential term sharing means for sharing a differential term of a target value and a controlled variable by passing a second delay element, thereby achieving two degrees of freedom in differential time. (2) The P (proportional) and I (integral) adjustment means performs PI adjustment calculations in response to the deviation between the target value filter output obtained through the target value filter means and the controlled variable of the controlled object. In the adjustment device that applies an operation signal that is an adjustment calculation output to the controlled object, the target value filter means includes: a gain coefficient multiplier that multiplies the target value by a two-degree-of-freedom coefficient of a proportional gain; a first first-order lag element that provides a first-order lag to the subtracted output obtained by subtracting the output of the gain coefficient multiplication means; an output of the first first-order lag element is set as an output of the gain coefficient multiplication means; a proportional gain two-degree-of-freedom means having a means for adding; a coefficient multiplication means for multiplying the target value by a two-degree-of-freedom coefficient for the proportional gain and a two-degree-of-freedom coefficient for the differential time; an output of the coefficient multiplication means; means for converting the output obtained by subtracting the control amount of the controlled object from the second first-order lag element and the second first-order lag element into two degrees of freedom for differential time. A two-degree-of-freedom adjustment device characterized by: (3) The P (proportional) and I (integral) adjustment means performs PI adjustment calculations in response to the deviation between the target value filter output obtained through the target value filter means and the controlled variable of the controlled object. In the adjustment device that applies an operation signal that is an adjustment calculation output to the controlled object, the target value filter means multiplies the target value by a two-degree-of-freedom coefficient of a proportional gain and a two-degree-of-freedom coefficient of a differential time. It has a coefficient multiplication means and a differential term sharing means for sharing the differential term of the target value and the controlled quantity by subtracting the controlled quantity of the controlled object from the output of the coefficient multiplication means and passing it through a first-order lag element. and a two-degree-of-freedom adjustment characterized in that nonlinear means is provided for performing nonlinear processing on the deviation when at least a differential term of the controlled variable is taken into the target value filter means and introducing it into the P and I adjustment means. Device.