JPH0762801B2 - Adaptive controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention is directed to a heat quantity mixing control device such as a heat exchanger, a chemical heating furnace, and a continuous annealing furnace, and water, calories, concentration, and components. The present invention relates to an adaptive control device used for the material mixture control device, etc., and particularly to an adaptive control device provided with means for optimizing the gain of feedforward control according to the environmental change of the process.

(Prior Art) In recent years, in manufacturing plants and the like, by appropriately changing the operation of the plant in accordance with changes in economic conditions, the motivation to flexibly manufacture high-quality products that are stoffless, and accordingly There is a demand for advanced feedforward control technology.

Conventionally, under such a demand, a gain adaptive (automatic correction) control device of a feedforward model applied to a heat exchanger as shown in FIG. 4 has been developed. That is, this adaptive control device is composed of a feedback control system and a feedforward control system, and the former feedback control system is
After the deviation e η is obtained from the target value SV (Ts) and the process variable PV obtained by measuring the control amount X in the comparison unit 1, the deviation e η is guided to the adjustment unit 2 to perform the velocity type PID calculation. The PID calculation output ΔCη of the adjustment unit 2 is introduced into the multiplication unit 3, where the calculation output ΔCη is multiplied by the gain kη corresponding to the magnitude of the load flow rate to perform gain scheduling. The signal obtained by this gain scheduling is introduced into the velocity type / position type signal conversion unit 5 after adding the static characteristic compensation amount in the addition unit 4 and converted into the position type signal, and then added to the addition unit 6
To the control target 7 such as a heat exchanger, and the control amount X is adjusted.

On the other hand, the feedforward control system performs gain scheduling according to the disturbance signal D (Fi) such as the load flow rate. Specifically, the output E η of the multiplication unit 10 obtained according to the magnitude of the load flow rate is guided to the gain ratio calculation unit 11, where the signal E η is multiplied by (1 / E ₀ ) to obtain the gain according to the load flow rate.・
A scheduled signal kη = Eη / E ₀ is obtained, and this is given to the multiplier 3 to automatically correct the gain of the feedforward control.

The multiplication unit 10 multiplies the disturbance signal D (Fi) by the gain coefficient kη and introduces the obtained signal Eη into the multiplication unit 12. The multiplication unit 12 multiplies the signal E η from the multiplication unit 10 by a signal of a difference between the heat exchanger outlet desired temperature set value SV (Ts) from the subtraction unit 13 and the heat exchanger inlet temperature Ti, and feedforward control is performed. Obtain the signal FFη. A static characteristic compensating means and a dynamic characteristic compensating means are provided on the output side of the multiplying section 12, and the feedforward control signal is divided into a static characteristic compensating component and a dynamic characteristic compensating component to compensate for disturbance. The static characteristic compensating means is provided with a difference calculating section 14 and a switch 15b, and the feedforward control signal FFη is exchanged with the speed type signal here and then supplied to the adding section 4 through the switch 15b. On the other hand, the operation characteristic compensation means is provided with an incomplete differentiating section 16 and a switch 15c, and the feedforward control signal FFη from the multiplying section 12 is taken out by the incomplete differentiating section 16 and the dynamic characteristic change is taken out through the switch 15c. Is given to. Then, the gain coefficient Kη of this feedforward control is determined as follows. That is, the determination of the gain coefficient Kη is performed by the subtraction unit 17 by the feedforward control signal FFη and the output signal of the velocity-position type signal exchange unit 5.
The deviation signal ΔMη with respect to MVη is acquired, and the control deviation signal eη, the static characteristic compensation component signal, and the operation characteristic compensation signal are extracted and introduced into the corresponding signal level detection units 18 to 21. The signal level detection unit 18 outputs an ON signal (H) when the deviation signal ΔMη exceeds a predetermined range, and the other signal level detection units 19 to 21 output the ON signal when the input signal is within the predetermined range. (H) is output. When the ON signals are output from all of the signal level detection units 18 to 21, the activation control signal is transmitted from the AND circuit 22 and the timer is activated.
Start up 23. The timer 23 outputs a gain correction timing signal and turns on the switch 15a after a lapse of a predetermined time after starting. When the switch 15a is turned on, the deviation signal ΔMη is introduced into the feedforward gain coefficient correction calculation unit 24 via the switch 15a, where the gain coefficient kη of the feedforward control is determined, and the gain is calculated based on this gain coefficient kη.・ Schedule.
That is, the correction calculation unit 24 corrects the reference gain coefficient k ₀ 25 using the integral of the deviation ΔMη and the coefficient k, guides the gain coefficient kη obtained to the multiplication unit 10, and the deviation signal ΔM of the subtraction unit 17
The gain coefficient of feedforward control is corrected so that η becomes zero. When correcting the gain coefficient, switch 15
Although b and 15c are in the OFF state, this is to suppress the fluctuation in the manipulated variable that occurs when the feedforward gain coefficient is corrected.

(Problems to be Solved by the Invention) However, the above-described automatic gain correction means for feedforward control is a method of determining a gain coefficient based on a stable condition by taking in a large number of operating state signals from each part of the device. Therefore, there is a problem that it is very difficult to obtain the timing according to the process state, and the accuracy of the gain coefficient is significantly deteriorated when the stability condition is loosened.

Further, this automatic gain correction means has a very complicated structure because it is provided with a large number of functions. Moreover, since many loop controllers adopt the distributed type, in this case, it is difficult to incorporate many functions because the memory capacity is restricted due to the downsizing of the entire apparatus and the sharing of functions. . If all the functions shown in FIG. 4 are included, a large amount of calculation processing and its processed data are required, so that a considerable memory capacity is required, and all the functions are included. The current situation is that it will be quite difficult.

The present invention has been made in view of the above-mentioned circumstances, and can automatically correct the gain of the control system continuously regardless of the correction timing of the gain coefficient, and has a simple configuration without affecting other functions. It is an object of the present invention to provide an adaptive control device that can be realized in a high degree of adaptive control and can flexibly respond to economic fluctuations of a plant.

[Configuration of the Invention] (Means for Solving the Problems) The adaptive control device according to the first invention adjusts the gain ratio signal that changes according to the magnitude of the feedforward control gain and the load signal of the feedback control system. A gain scheduling means for multiplying and combining the partial output signals to modify the gain, and an operation signal of a control target, the gain of which is modified by the gain scheduling means, is changed according to the feedforward control gain and the magnitude of the load signal. It is provided with a gain scheduling compensating means for dividing by the gain signal and varying the gain ratio of the gain scheduling means according to the obtained divided signal.

An adaptive control apparatus according to a second aspect of the present invention provides the means of the first aspect of the present invention with a static characteristic compensation component of a feedforward control signal based on the load signal, which is added to the adjustment unit output signal corrected by the gain scheduling means. A static characteristic compensating means for compensating the static characteristic is added, and the operation signal of the control target after compensation by the static characteristic compensating means is divided by the feedforward control signal based on the load signal, and the static signal is calculated according to the obtained division signal. The signal after the characteristic compensation is changed to perform gain scheduling.

Next, the adaptive control device according to the third invention multiplies the means of the second invention by the output of the gain scheduling compensating means and the dynamic characteristic compensation portion of the feedforward control signal based on the load signal, and multiplies this multiplied signal. An operation characteristic compensating means for adding dynamic compensation to a signal after gain compensation is added.

(Operation) Therefore, according to the first aspect of the present invention, by adopting the above-mentioned means, the gain scheduling means is used to determine the gain
Scheduling is performed, but if the feedforward control gain is not a gain that matches the load condition, a gain correction mismatch occurs. Therefore, a gain / scheduling compensating means is provided, and the output of the adjusting section is varied by using the operation signal of the controlled object after the gain / scheduling, the feedforward control gain, and the gain that changes according to the magnitude of the load signal. It is intended to compensate the gain correction mismatch caused by the feedforward control gain.

According to a second aspect of the present invention, by adopting the above means, gain scheduling is performed using the gain scheduling means based on a predetermined feedforward control gain, and the static characteristic compensation means is used to obtain the gain. The static characteristic compensation is performed by giving the static characteristic compensation amount of the feedforward control signal based on the load signal to the adjustment unit output signal corrected by the scheduling means, but the feedforward control gain is adapted to the load state. If it is not a gain, a gain correction mismatch occurs. Therefore, a gain / scheduling compensating means is provided, and the output of the adjusting section is varied by using the operation signal of the controlled object after the gain / scheduling, the feedforward control gain, and the gain that changes according to the magnitude of the load signal. Compensation of gain correction mismatch caused by the feedforward control gain Next, the third invention divides the feedforward control signal based on the load signal into a static characteristic compensation component and an operation characteristic compensation component, and particularly, For dynamic characteristic compensation, the output of the incomplete differentiator and the compensation signal of the gain scheduling compensation means are multiplied,
The obtained multiplication signal is given to the operation signal to be controlled to perform dynamic characteristic compensation.

(Embodiment) An embodiment of the first invention device will be described below with reference to FIG. In the figure, the same parts as those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

First, the feedback control system has exactly the same configuration as the conventional device except for the static characteristic compensation and dynamic characteristic compensation portions. Hereinafter, the configuration of the feedforward control system will be described exclusively. This feedforward control system comprises gain scheduling means 30 and gain scheduling compensation means 40. Gain scheduling means
The reference numeral 30 multiplies a disturbance signal D (Fi) such as a load flow rate by a feedforward control gain coefficient K predetermined by the load flowrate signal or the like, and depends on the magnitude of the load flowrate signal and the feedforward control gain coefficient K. A gain coefficient unit 31 that obtains a changing gain signal Eη, and this gain coefficient unit 31
The gain signal E η obtained in step ₁ is divided by the gain signal E η (= E ₀ ) obtained when the PID parameter of the adjusting section 2 is determined to obtain a gain ratio signal. Gain scheduling is performed by introducing and multiplying the gain ratio signal k (= Eη / E ₀ ) obtained by the gain ratio calculation unit 32 into the multiplication unit 3 together with the adjustment unit output signal.

The gain scheduling compensation means 40
The operation signal, which is the output of the velocity-position type signal exchange unit 5 whose gain is corrected by the scheduling means 30, is divided by the gain signal Eη which changes depending on the magnitude of the load flow rate signal and the feedforward control gain coefficient K, Dividing unit 41 for acquiring a compensation signal based on gain correction mismatch
And a gain unit 42 provided on the output side or the input side (not shown) of the gain ratio calculation unit 32, which multiplies with the signal kη or Eη to change the gain ratio.

Therefore, according to the configuration of the above-described embodiment, the gain scheduling according to the load flow rate is performed using the predetermined feedforward gain coefficient k, but the gain coefficient k matches the control system due to the change in the load flow rate. It disappears, and so-called gain correction causes mismatching. Therefore, the present apparatus takes in the operation signal MVn of the controlled object 7 after the gain scheduling, and the operation signal MVn
Is divided by the gain signal En to obtain a compensation signal, and then the compensation signal is multiplied by the output side or the input side of the gain ratio calculation unit 32 of the gain scheduling means 30, and the gain ratio signal is varied to obtain the gain. Compensate for correction mismatch.

The reason for compensating the mismatch of the gain correction in this way is as follows. That is, it is ideal that the operation signal MVn from the signal conversion unit 5 which is the final operation output and the gain signal En obtained by multiplying the load signal taken in as the feedforward control by the feedforward control gain match. . However, when the gain signal En is not appropriate, that is, when a deviation occurs in the gain signal En, the feedback control system gradually supplements it. However, until the feedback control system exerts a complete complementing function, the signal conversion unit 5 There is a difference between the operation signal MVn that is the output of the control signal MVn and the gain signal En, and control instability cannot be denied. Therefore,
The purpose is to obtain the compensation signal by obtaining the difference between the operation signal MVn and the gain signal En as a ratio, and to compensate the mismatch due to the gain correction.

Next, an embodiment of the second invention device will be described with reference to FIG. In this device, the feedback control system is exactly the same as the conventional device except for the dynamic characteristic compensation part. On the other hand, the feedforward control system is provided with static characteristic compensating means 50 in addition to gain scheduling means 30 and gain scheduling compensating means 40. The gain scheduling means 30 introduces a disturbance signal such as a load flow rate signal of the heat exchanger into the gain coefficient section 31, where the load flow rate signal is multiplied by the feedforward gain coefficient K to determine the magnitude of the load flow rate signal. After obtaining the gain signal E η that depends on the feedforward control gain coefficient K,
It is supplied to the gain ratio calculation unit 32. This gain ratio calculator
32 divides the gain signal E η by E ₀ (E ₀ is the magnitude of E η when the PID parameter of the adjusting unit 2 is determined), obtains the gain ratio signal k η (= E η / E ₀ ), and the multiplying unit 3 The gain correction signal is supplied to the adder unit 4 after gain scheduling is performed by multiplying the speed type output signal ΔCη of the adjusting unit 2 by the load flow rate.

Next, the static characteristic compensating means 50 introduces the output of the gain coefficient section 31 into the multiplication section 51, and outputs the gain coefficient section output and the temperature (Ts-Ti) to be heated by the heat exchanger from the subtraction section 52. The position feedforward signal FFη is multiplied to obtain the position feedforward signal FFη, which is supplied to the difference calculation unit 53. The difference calculation unit 53 obtains a velocity feedforward signal from the difference between the previous position feedforward signal and the current position feedforward signal, guides it to the addition unit 4 as a static characteristic compensation component, and feeds the velocity type feedback after the gain scheduling. Addition and synthesis with the control signal (kη ・ ΔCη
+ ΔFF η) signal is acquired.

Further, in the gain / scheduling compensating means 40, the position type feedforward control signal FFη obtained by the multiplying part 51 is introduced into the subsequent dividing part 41, and this signal FFη and the velocity type / position type signal exchanging part 5 are introduced. MVη / FFη is obtained using the operation signal MVη which is the output signal of. Then, a multiplication unit 4 is provided between the addition unit 4 and the velocity-position type signal exchange unit 5.
2 ′ is provided, the signal (MVη / FFη) obtained by the divider 41 is introduced into the multiplier 42 ′, and the output (kη · ΔCη + ΔFFη) of the adder 4 after static characteristic compensation is multiplied to correct the gain. Obtain the signal ΔMVη. That is, ΔMVη = (kη · ΔCη + ΔFFη) · (MVη / FFη) ...
(1) Then, this signal ΔMVη is the speed type-position type signal exchange section 5
Introduced into MV η = MV _n−1 + ΔMV η (2), the signal MV _n−1 is used as the operation signal for the controlled object 7.

Next, in explaining the operation of the apparatus configured as described above, in order to facilitate understanding, it will be described in relation to the conventional apparatus. The automatic gain correction of the conventional device compensates the mismatch due to the feedforward control by the feedback control so that the control output (operation signal MVη) obtained by the addition and synthesis of the feedforward control and the feedback control becomes equal to the feedforward control output FFη. The feed-forward control gain correction is performed to eliminate the feed-forward control mismatch (prediction control error). That is, when the reference value of the feedforward control output FFη is FFη ₀ , it can be expressed by FFη ₀ = K ₀ · (Ts−Ti) · Fi = K ₀ · Eη (3). If the operation signal MVη at this time is MVη ≠ FFη, it means that the feedforward control mismatch occurs. Therefore, in the subtraction unit 17, MVη and FF
If the difference from η exceeds the specified range, switch 14a
It is necessary to correct the gain coefficient K ₀ to K ₁ in the feed-forward gain coefficient correction calculation unit 24 so that MV η = FF η by closing, and therefore the gain coefficient x to be corrected needs to be obtained.

K ₁ = x · K ₀ (4) FFη = K ₁ · (Ts−Ti) · Fi = x · K ₀ · (Ts−Ti) · Fi = MVη ∴x = MVη / FFη ₀ (5) Calculated from the formula. Further, in FIG. 4, since K ₁ = K ₀ + ΔK, the gain coefficient ΔK to be corrected from this equation is
ΔK = K ₁ −K ₀ = x · K ₀ −K ₀ = K ₀ (x−1) = K ₀ {(MVη / FFη ₀ ) −1} = K ₀ · {(MVη−FFη ₀ ) / FF η ₀ } (6) Therefore, K ₁ = K ₀ + ΔK = K ₀ + K ₀ {(MV η-FF η ₀ ) / FF
η ₀ } = K ₀ · (MV η-FF η ₀ ) = K ₀ · x (7) Both of these equations (5) and (6)
= Gain correction method to satisfy FFη, and the result is exactly the same.

Further, if the disturbance signal changes after the automatic gain correction of this feedforward control, the feedforward control output FF _{n + 1} is FF _{n + 1} = K ₁ · E _{n + 1} = x · K ₀ · E _{n + It} can be understood that ₁ = x · K ₀ · Eη · (Eη _{n + 1} / Eη) = FFη · (E _{n + 1} / Eη) = MVη · (E _{n + 1} / Eη) (8). Then, after converting this equation (8) into the velocity type for static characteristic compensation, when it is calculated as the change amount ΔFFη ′ of the feedforward control output after this gain correction, ΔFFη ′ = FF _{n + 1} −FFη = FF _{n + 1} η−MVη = MVη · (E _{n + 1} / Eη) −MVη = MVη · {(E _{n + 1−} Eη) / Eη} = MVη · {(MV _{n + 1−} FFη) / FFη} = ΔFFη · MVη / FFη) (9) is obtained.

On the other hand, in the device of the present invention, the gain-corrected output k
By giving the static characteristic compensation signal ΔFFη to η · ΔCη, an operation signal MVη from the signal conversion unit 5 to the controlled object 7 is obtained, and this operation signal is divided by the feedforward control signal FFη depending on the load flow rate, and the multiplication unit 42 ' If it is given as a scheduling compensation signal to ΔFFη ′, ΔFFη ′ = ΔFFη · (MVη / FFη) (10) as ΔFFη ′, which is the static characteristic compensation amount of the feedforward control. This equation (10) provides exactly the same compensation as the above equation (9). Here, since it can be expressed as MVη = FBη + FFη (11), the equation (10) becomes ΔFFη ′ = ΔFFη · {1+ (FBη / FFη)} (12). However, FBη is a feedback control component, and FFη is a feedforward control component. That is, the change in the feedforward control output may be corrected according to the ratio of the feedback control component to the feedforward control component. This means that the present apparatus can perform feedforward control without having the timing acquisition means, the gain coefficient calculation means and the like unlike the conventional apparatus.

Therefore, according to the configuration of the above-described embodiment, after the speed-type feedback control signal and the speed-type feedforward control signal, which are gain-scheduled based on the load flow rate signal, are added and combined, the operation signal is converted into the feedforward control signal. The gain of the control system can be automatically adapted to the optimum state by multiplying the divided value and converting this signal into the position type signal to be the operation signal. Moreover, since the timing signal acquisition means and the gain coefficient correction calculation unit, which are required in the conventional apparatus, are not required, the configuration can be greatly simplified, and the automatic gain correction can be performed without affecting other functions. It can handle high levels of adaptability because it can be done at all times. In addition, since the overall structure of the device is simple, it can be distributed and arranged in the plant, the plant can be activated, and the change in productivity due to the economic fluctuation can be highly dealt with, which greatly contributes to the flexibility of the plant operation.

In the above embodiment, the configuration in which the static characteristic compensating means 50 is provided has been described, but it is also applicable to the one in which the feedforward control dynamic characteristic compensating means 60 is provided as shown in FIG. That is, an incomplete differentiator 61 is provided for dynamic characteristic compensation, the output of the incomplete differentiator 61 is multiplied by the gain / scheduling compensation signal in the multiplier 62, and this multiplication value is added by the adder.
The configuration may be such that it is guided to 63, added to the operation signal, and applied to the controlled object 7. Further, although the present apparatus has been described with respect to the gain correction of the feedforward control, it can be similarly applied to the gain correction of the feedback control. In addition, the gain scheduling function of the above embodiment is the gain ratio calculation unit 32.
According to the following relationship, kη = Eη / E ₀ = (K · D) / (K · D ₀ ) = D / D ₀ (13), the disturbance signal D from the input side of the gain coefficient unit 31 Alternatively, the disturbance signal D may be multiplied by 1 / D ₀ , and gain scheduling may be performed based on kη = D / D ₀ . Furthermore, although the gain scheduling function is described as being linearly corrected, it may be performed by using a function calculation correction or a polygonal line correction which is a non-linear correction. In addition, the present invention can be modified in various ways without departing from the scope of the invention.

[Advantages of the Invention] As described in detail above, according to the present invention, the gain of the control system can be automatically corrected continuously regardless of the gain coefficient determination timing, and the other functions are affected. It is possible to provide an adaptive control device that enables a high degree of adaptation with a simple configuration without any use and can be used flexibly according to the economic fluctuation of the plant.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an adaptive control device according to the first invention, FIG. 2 is a block diagram showing an embodiment of a second invention device, and FIG. 3 is a view showing a third invention device. FIG. 4 is a block diagram showing an embodiment, and FIG. 4 is a block diagram showing a conventional device. 1 ... Comparison unit, 2 ... Adjusting unit, 3 ... Multiplying unit, 5 ... Velocity type to position type signal converting unit, 7 ... Control object, 30 ... Gain scheduling means, 31 ... Gain coefficient unit , 32 ...
... Gain ratio calculation unit, 40 ... Gain / scheduling compensation means, 41 ... Division unit, 42, 42 '... Multiplication unit, 50 ...
Static characteristic compensation means, 51 ... Multiplying section, 52 ... Difference calculating section, 60
...... Dynamic characteristic compensation means, 61 …… Incomplete differentiation section, 62 …… Multiplication section, 63 …… Addition section.

Claims (3)

[Claims] 1. An adaptive control device for correcting a gain of feedforward control by combining a feedforward control system using a load signal with a feedback control system, wherein the gain varies according to the magnitude of the feedforward control gain and the load signal. Gain scheduling means for multiplying and combining the ratio signal with the output signal of the control section of the feedback control system to correct the gain, and the feed-forward control gain and load for the operation signal of the control object whose gain is corrected by the gain scheduling means. Divide by a gain signal that changes according to the magnitude of the signal,
A gain scheduling compensating means for varying the gain ratio of the gain scheduling means according to the obtained division signal, and adaptive control characterized by compensating a gain correction mismatch caused by the feedforward control gain. apparatus. 2. An adaptive control device for correcting the gain of feedforward control by combining a feedforward control system using a load signal with a feedback control system, wherein the gain varies according to the magnitude of the feedforward control gain and the load signal. Gain scheduling means for multiplying and combining the ratio signal with the output signal of the adjusting section of the feedback control system to adjust the gain, and feedforward control based on the load signal to the output signal of the adjusting section corrected by the gain scheduling means. A static characteristic compensating means for compensating the static characteristic by giving the static characteristic compensation component of the signal;
Gain-scheduling compensating means for dividing the operation signal to be controlled after compensation by the static characteristic compensating means by the feedforward control signal based on the load signal, and varying the signal after static characteristic compensation according to the obtained division signal. And an adaptive control device for compensating for a mismatch in gain correction caused by the feedforward control gain. 3. An adaptive control device for correcting the gain of feedforward control by combining a feedforward control system using a load signal with a feedback control system, wherein the gain changes according to the magnitude of the feedforward control gain and the load signal. Gain scheduling means for multiplying and combining the ratio signal with the output signal of the adjusting section of the feedback control system to adjust the gain, and feedforward control based on the load signal to the output signal of the adjusting section corrected by the gain scheduling means. A static characteristic compensating means for compensating the static characteristic by giving the static characteristic compensation component of the signal;
Gain-scheduling compensating means for dividing the operation signal of the control target after compensation by the static characteristic compensating means by the feedforward control signal based on the load signal, and varying the signal after static characteristic compensation according to the obtained division signal. And a dynamic characteristic compensating means for multiplying the output of the gain scheduling compensating means by the dynamic characteristic compensating amount of the feedforward control signal based on the load signal and giving the multiplied signal to the signal after gain compensation to perform the dynamic characteristic compensation. An adaptive control device, comprising: a gain correction mismatch caused by the feedforward control gain.