JPH0871627A - Controller - Google Patents

Abstract

PURPOSE: To obtain such controller for a continuous rolling mill which maintains a control system always stably and realize a looper control able to respond in high speed regardless of changes in the dynamic characteristics of a rolling process. CONSTITUTION: The controller 0 is structured such that the position of a looper 3 is detected which imparts tension to a rolling stock 2 to be rolled by roller stands 1, 1 arranged in tandem, and that a continuous rolling mill is controlled by a control system which corrects the roller speed of the stands 1, 1 on the basis of the detected data. In this case, the controller is also provided with a parameter estimation device 7a, which operates the attenuation coefficient of the transfer function of the control system based on the detected data of the looper position, and an interpolative PI controller 7b which sets the control gain of the control system based on the computed attenuation coefficient and the maximum and minimum values of a prestored attenuation coefficient. With this structure, a looper control is realized which always stably maintains the control system and which enables a high speed responsiveness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller of a feedback control system for controlling height and position, for example, a controller for controlling the looper height for controlling tension between stands and looper position of rolled material in a continuous rolling mill. It is about.

[0002]

2. Description of the Related Art A control device of a feedback control system for controlling height and position is applied to a wide range of fields. For example, in a continuous rolling mill as shown in FIG. 17, the tension of the material to be rolled between the stands has a great influence on the product, strip thickness, strip width, and strip shape accuracy. Constant control is required. For this reason,
A looper is installed between each stand. The looper moves and absorbs momentary tension fluctuations, but the tension in a steady state is determined by the looper height (looper angle). Therefore, how to control the looper height near the set position under rolling disturbance is an important issue. FIG. 18 shows a control device 0'of a conventional continuous rolling mill. In FIG. 18, each stand 1,
An appropriate torque is applied to the looper 3 by the looper motor 4 so that the tension of the material to be rolled 2 between 1 becomes an appropriate value. The looper height is based on the deviation between the looper position detected by the looper angle detector 5 and the looper set position set by the looper position setter 6, and the PI controller 7b 'in the looper position controller 7'rolls the adjacent stand. Controlled to modify speed. That is, P
A signal is sent to the speed controller 9 of the mill motor 8 by the I controller 7b 'so that the position of the looper 3 can be stably returned to and held at the set position via the length of the material 2 to be rolled between the stands 1 and 1. Feedback control is implemented in. A block diagram of this control system is shown in FIG. Many control devices of a feedback control system that control the height and position have the same configuration.

[0003]

The conventional controller 0'of the continuous rolling mill as described above has the following problems. The response characteristics of a looper system can be generally expressed by its frequency characteristics, but under actual operating conditions, that is, under various rolling materials and rolling conditions that change during rolling,
The frequency characteristics of the looper system are fluctuating. For example, the gain peak value at the resonance frequency of the looper system fluctuates due to the characteristics of the rolled material, and the gain at high frequencies increases due to the effect of observation noise. PI in conventional device 0 '
In control, the feedback gain due to the proportional action element (P) and the integral action element (I) is controlled by the control system (looper height system).
It was a constant value over the entire frequency range, without taking into account the fluctuations in the frequency characteristics of. Therefore, the looper height may become unstable when the frequency characteristics of the control system fluctuate. This problem is common to all feedback control system control devices that have the same configuration and control the height and position. The first, second, and third inventions, in order to solve the problems in the prior art, improve the control device so that the fluctuation of the frequency characteristics of the control system is particularly large. By considering the variation of parameters such as damping coefficient that affects stability, the response characteristics are good,
Further, it is an object (first object) to provide a control device capable of realizing height and position control such as looper height and the like, which is also excellent in stability. Further, the fourth invention is a control capable of realizing height and position control such as looper height having good response characteristics and excellent stability by automatically adjusting the control gain in accordance with fluctuations in frequency characteristics. The purpose is to provide a device (second purpose). On the other hand, in the control gain tuning of conventional equipment, the focus was on lowering the gain because of fear of trouble (unstable phenomenon). For this reason, quick response may be sacrificed in exchange for ensuring stability. A fifth aspect of the invention can realize height and position control with good response characteristics and excellent stability by automatically adjusting the control gain including the increase thereof within a range where stability can be ensured. The purpose (third purpose) is to provide a control device.

[0004]

In order to achieve the above first object, the first invention is to detect the position of a looper which gives a tension to a material to be rolled by a roller stand arranged in tandem, In a controller of a continuous rolling mill equipped with a control system for correcting the roller speed of the stand based on the detected data, a transfer function of the control system of the control system is calculated based on the correction amount of the roller speed and the detected data of the looper position. And a control gain setting means for setting the control gain of the control system based on the damping coefficient calculated by the calculating means and the maximum and minimum values of the damping coefficient stored in advance. It is configured as a control device for a continuous rolling mill. Further, it is a control device for a continuous rolling mill, wherein the transfer function has a second-order lag element and a dead time element. Furthermore, the control gain of the control system is a control device for a continuous rolling mill having proportional operation elements and integral operation elements. Further, it is a control device for a continuous rolling mill that uses the recursive least squares method for the calculation of the damping coefficient by the calculation means. A second aspect of the present invention includes a control system that detects the position of the looper that applies tension to the material to be rolled by a tandem-arranged roller stand and corrects the roller speed of the stand based on the detected data. In a control device for a continuous rolling mill, a first stability calculation means for calculating stability of the looper position based on the detection data of the looper position, a correction amount of the roller speed and detection data of the looper position. First parameter calculating means for calculating the damping coefficient of the transfer function of the control system based on the above, and the first parameter calculating means for calculating the damping coefficient of the control system when the stability calculated by the first stability calculating means exceeds a threshold value. A first control gain for setting the control gain of the control system based on the damping coefficient calculated by the parameter calculating means and the correspondence relationship between the damping coefficient and the control gain stored in advance. A control device for the continuous rolling mill, characterized by comprising; and a constant section.

Further, it is a controller for a continuous rolling mill, wherein the transfer function comprises a second-order lag element and a dead time element.
Furthermore, the control gain of the control system is a control device for a continuous rolling mill having proportional operation elements and integral operation elements. Further, it is a controller for a continuous rolling mill that uses the recursive least squares method for calculating the damping coefficient by the first parameter calculating means. A third aspect of the invention is calculated by the second parameter calculating means for calculating the parameter of the transfer function of the control system including the controlled object based on the input / output data for the controlled object, and the second parameter calculating means. A second setting of the control gain of the control system based on the correspondence relationship between the parameter and the previously stored parameter and the control gain
Control gain setting means. In order to achieve the above-mentioned second object, a fourth invention is to detect the position of a looper which gives a tension to a material to be rolled by a roller stand arranged in tandem, and based on the detected data, the roller of the stand is detected. In a controller of a continuous rolling mill having a control system for correcting the speed, second stability calculation means for calculating the stability of the looper position based on the detection data of the looper position, and the correction amount of the roller speed. And the stability calculated by the second stability calculation means exceeds the threshold value, and the third parameter calculation means calculates the parameter of the transfer function of the control system based on the detection data of the looper position. At this time, the control gain of the control system is set online based on the dynamic characteristic of the transfer function using the parameter calculated by the third parameter calculating means. And it is configured as a control device of a continuous rolling mill, characterized by comprising; and a third control gain setting means.

Further, it is a control device for a continuous rolling mill in which the dynamic characteristic of the transfer function is composed of a second-order lag element and a dead time element. Furthermore, the control gain of the control system is a control device for a continuous rolling mill having proportional operation elements and integral operation elements. Further, the control system is a control device for a continuous rolling mill in which the control system is an IP control system. Further, it is a controller for a continuous rolling mill that uses the recursive least squares method for calculating the parameters of the transfer function by the third parameter calculating means. Further, it is a controller for a continuous rolling mill that uses a partial model matching method for setting the control gain by the third control gain setting means. In order to achieve the third object, a fifth invention is a fourth parameter calculating means for calculating a parameter of a transfer function of a control system including the controlled object based on input / output data for the controlled object, and the fourth invention. Fourth control gain setting means for setting the control gain of the control system by performing interpolation calculation based on the parameter calculated by the parameter calculating means of No. 4 and the correspondence relationship between the parameter stored in advance and the control gain. An interpolation frequency calculation means for calculating the frequency of interpolation calculation due to occurrence of hunting in the control system when the control gain is set by the fourth control gain setting means, and an interpolation calculation frequency calculated by the interpolation frequency calculation means In accordance with the above, it is configured as a control device including a correspondence relationship changing means for changing the correspondence relationship between the parameter and the control gain. . Furthermore,
When the frequency of the interpolation calculation calculated by the interpolation frequency calculation means is smaller than a predetermined upper limit value, the control gain is set large, and when the frequency is larger than the predetermined lower limit value, the control gain is set small. The control device sets the control gain by the fourth control gain setting means. Further, the control device stores in advance a correspondence relationship between the parameter and the control gain in a memory for each type of the controlled object.

[0007]

According to the first aspect of the present invention, the control system for detecting the position of the looper which gives tension to the material to be rolled by the roller stand arranged in tandem and correcting the roller speed of the stand based on the detected data. Thus, when controlling the continuous rolling mill, the damping coefficient of the transfer function of the control system is detected by the computing means based on the correction amount of the roller speed and the detection data of the looper position. The control gain of the control system is set by the control gain setting means based on the damping coefficient calculated by the calculating means and the maximum and minimum values of the damping coefficient stored in advance. in this way,
Of the fluctuations in the frequency characteristics of the control system, the fluctuations are particularly large,
By considering the variation of the damping coefficient that affects the stable control of the control system, it is possible to realize the looper height control with good response characteristics and excellent stability. According to the second aspect of the invention, the position of the looper that applies the tension to the material to be rolled is detected by the roller stands arranged in tandem, and the control is performed by the control system that corrects the roller speed of the stand based on the detected data. When controlling the rolling mill, the stability of the looper position is calculated by the first stability calculating means based on the detection data of the looper position. The damping coefficient of the transfer function of the control system is calculated by the first parameter calculating means based on the correction amount of the roller speed and the detection data of the looper position. The first
When the stability calculated by the stability calculating means exceeds the threshold value, the damping coefficient calculated by the first parameter calculating means and the correspondence relationship between the damping coefficient stored in advance and the control gain. Based on the above, the control gain of the control system is set by the first control gain setting means. still,
When the stability calculated by the first stability calculating means does not exceed the threshold value, the control gain stored in advance is set by the first control gain setting means. In this way, when the stability of the control system collapses due to the variation of the frequency characteristic of the control system, the response characteristic is improved by considering the variation of the damping coefficient that affects the stability of the control system.
Further, it is possible to realize the looper height control which is excellent in stability.

According to the third invention, the parameter of the transfer function of the control system including the control target is calculated by the second parameter calculating means based on the input / output data for the control target. The control gain of the control system is set by the second control gain setting means based on the parameter calculated by the second parameter calculating means and the correspondence relationship between the parameter and the control gain stored in advance. In this way, among the fluctuations in the frequency characteristics of the control system, the fluctuation is particularly large, and by considering the fluctuations in the parameters that affect the stability of the control system, the response characteristics are good and the stability is excellent. Control of the pod position can be realized. Fourth
According to the invention, the continuous rolling mill is controlled by a control system that detects the position of the looper that gives tension to the material to be rolled by the roller stand arranged in tandem and corrects the roller speed of the stand based on the detected data. When performing the control of 1, the stability of the looper position is calculated by the second stability calculating means based on the detection data of the looper position. The parameter of the transfer function of the control system is detected by the third parameter calculating means based on the correction amount of the roller speed and the detection data of the looper position. When the stability calculated by the second stability calculation means exceeds a threshold value, based on the dynamic characteristic of the transfer function using the parameter calculated by the third parameter calculation means, The control gain of the control system is set online by the third control gain setting means. In addition, the first
When the stability calculated by the stability calculating means of 1 does not exceed the threshold value, the control gain stored in advance is equal to the first control gain.
It is set by the control gain setting means.

As described above, by automatically adjusting the control gain in accordance with the variation of the frequency characteristic, it is possible to realize the control of the height and the position such as the looper height having the excellent response characteristic and the excellent stability. According to the fifth aspect of the present invention, the parameter of the transfer function of the control system including the control target is calculated by the fourth parameter calculation means based on the input / output data for the control target. The control gain of the control system is set to the fourth control gain setting means by performing interpolation calculation based on the parameter calculated by the fourth parameter calculation means and the correspondence relationship between the parameter and the control gain stored in advance. Set by. The interpolation frequency calculation means calculates the frequency of the interpolation calculation due to the occurrence of hunting of the control gain when the control gain is set by the fourth control gain setting means. The correspondence relationship changing means changes the correspondence relationship between the parameter and the control gain according to the frequency of the interpolation calculation calculated by the interpolation frequency calculating means. In this way, by automatically adjusting the control gain including the increase within the range where stability can be secured, the response characteristics are good,
Further, it is possible to realize the control of the height and the position which are excellent in stability.

[0010]

Embodiments of the present invention will be described with reference to the accompanying drawings.
Examples will be described to provide an understanding of the present invention. In addition,
The following example is an example embodying the present invention.
It does not limit the technical scope of the. here,
FIG. 1 is a block diagram of a first embodiment of the invention (first embodiment).
FIG. 2 is a schematic diagram showing a schematic configuration of the control device 0 of the continuous rolling mill.
Explanatory diagram showing the input-output relationship to the looper position control device 7,
3 is the control performance of each looper angle by the control devices 0'and 0
4 is a comparative diagram showing the first embodiment of the second invention (second embodiment).
Control device 0 of continuous rolling mill according to example)_xThe schematic configuration of
5 is a schematic diagram, and FIG. 5 is a looper position control device 7._xInput / output function to
FIG. 6 is an explanatory view showing a control unit, and FIG._xBy each
A comparative diagram showing the control performance of the looper angle, and FIG. 7 is a third invention.
Outline of control device 10 according to one embodiment (third embodiment)
FIG. 8 is a schematic diagram showing the structure of an embodiment of the fourth invention (fourth embodiment).
Control device 0 of the continuous rolling mill according to_ySchematic configuration of
9 is a schematic diagram showing the looper position control device 7_yIn and out of
FIG. 10 is an explanatory diagram showing the force relationship, and FIG. 10 is a block of the IP control system.
Diagram, Fig. 11 shows controller 0_yFlow chart showing the operation procedure by
-Fig. 12, Fig. 12 shows control devices 0'and 0 _yBy each looper angle
FIG. 13 is a comparison diagram showing the control performance of the degree, FIG.
A schematic configuration of the control device 20 according to the embodiment (fifth embodiment) will be described.
Schematic diagram shown in FIG. 14, FIG. 14 is an explanatory diagram showing an example of hunting, and FIG.
5 is an explanatory diagram showing the effect of the interpolation control, and FIG. 16 is a modified example.
It is explanatory drawing which shows the interpolation method of the parameter. Incidentally, before
One of the control devices 0'of the conventional continuous rolling mill shown in FIG.
Elements common to the schematic diagram showing the schematic configuration in the example are the same
Use one code.

<First Invention> As shown in FIG. 1, a controller 0 of a continuous rolling mill according to an embodiment (first embodiment) of the first invention comprises roll stands 1, 1 arranged in tandem. The looper angle detector 5 detects the position of the looper 3 which gives a tension to the material 2 to be rolled by the miller speed controller 9 and outputs a signal for correcting the roller speed of the stands 1 and 1 to the mill motor speed controller 9 based on the detected data. It is the same as the conventional example in that it has a control system for emitting the light. However, in the first embodiment, a parameter estimating device 7a (corresponding to a calculating means) for calculating the damping coefficient of the transfer function of the control system based on the correction amount of the roller speed and the detection data of the looper position is used. ，
An interpolation type PI controller 7b (corresponding to a control gain setting means) that sets the control gain of the controller based on the attenuation coefficient calculated by the parameter estimation device 7a and the maximum and minimum values of the attenuation coefficient stored in advance. It is different from the conventional example in that it is equipped with. FIG. 2 is a block diagram showing a partial configuration of the first embodiment, and shows the flow of control signals for controlling the looper position to the set position.

The operation of the device 0 of the first embodiment and its basic principle will be described below with reference to FIGS. FIG.
In the above, the looper motor 4 applies an appropriate torque to the looper 3 so that the tension of the rolled material 2 between the stands 1 and 1 becomes an appropriate value. The looper height is based on the deviation between the looper position detected by the looper angle detector 5 and the looper setting position set by the looper position setting device 6, and the parameter estimation device 7a and the interpolation PI controller 7b in the looper position control device 7 are used. Is controlled to correct the rolling speed (corresponding to the roller speed) of the adjacent stand. Here, the parameter estimating device 7a and the interpolation type PI controller 7b which are the features of the first invention will be described in detail. [Parameter Estimator 7a] In the parameter estimator 7a, the damping coefficient is calculated from the online data of the speed correction amount of the mill motor 8 and the looper angle using the recursive least squares method. For example, in the case of a steel hot-finish rolling mill, the above control system (looper height system) is 2
It is known that it can be modeled by the transfer function of next delay + dead time. The well-known ARMA analysis is used for this analysis.

Here, the ARMA analysis refers to the following method (see “System Identification” by Setsuo Sagara et al., Japan Society of Instrument and Control Engineers). That is, the control object is expressed by the form as the following _{equation, y (k) + a 1} y (k-1) + ... + a n y (k-n) = b 1 u (k-1) + ... + b m u (k-m) + e (k) coefficients a _1, is that the model identification method of calculating the minimum square method ~a _n, b ₁ ~b _m. However, y (•) is an output, u (•) is an input, e (•) is white noise, k is the number of steps, and n and m are arbitrary natural numbers.

In order to perform this analysis, first, the three parameters represented by the following equation obtained by discretizing the transfer function are estimated, and then the damping coefficient is calculated using the estimated values.

[Equation 1]

[Equation 2] Here, p1, p2, p3 are parameters to be estimated, y
[•] is the looper angle, u [•] is the mill motor speed correction amount, k is the number of steps, L is the dead time, T is the sampling interval, {•} is the Gauss symbol, and ζ is the damping coefficient. Before the material to be rolled 2 reaches the continuous rolling mill, the variation range of the damping coefficient is grasped by the parameter estimating device 7a in advance, and the proportional operation elements of the control system when the damping coefficient takes the maximum and minimum values and The gain of the integral action element is calculated and stored in a memory (not shown).

[Interpolation type PI controller 7b] Proportional operating element and integral operation corresponding to the damping coefficient calculated by the parameter estimating device 7a during rolling and the maximum and minimum values of the damping coefficient previously stored in the memory. The gains of the proportional operation element and the integral operation element used for control are calculated based on the element gains, and the speed correction amount of the mill motor 8 necessary for the looper 3 to reach the set position is calculated. The gains of the proportional operation element and the integral operation element corresponding to the maximum damping coefficient are Kpmax and Kimax, and the gains of the proportional operation element and the integral operation element corresponding to the minimum damping coefficient are Kpmin, Kimin and the attenuation coefficient, respectively. Letting the maximum value be ζmax, the minimum value ζmin, and the estimated value of the damping coefficient be ζest, the transfer function of the interpolation type PI controller 7b is expressed by the following equation.

(Equation 3) A correction signal is sent to the speed controller 9 of the mill motor 8 by the interpolation PI controller 7b, and the position of the looper 3 is stably returned to the set position via the length of the material 2 to be rolled between the stands 1 and 1. Feedback control is carried out so as to hold it. The following is the result of simulation performed using the device 1 of the first embodiment described above.

FIG. 3 is a simulation result assuming a continuous hot rolling mill for steel. (A), (b) in the figure
Is due to the conventional controller 0 ', but (c),
(D) shows the control performance by the device 0 of the first embodiment. As described above, in the first embodiment, it is understood that the control performance excellent in stability and responsiveness is maintained even if the characteristics of the control system are changed as compared with the conventional example. As a result, according to the first embodiment, there is provided a controller for a continuous rolling mill capable of realizing looper control capable of always maintaining a stable control system and responding at high speed regardless of changes in dynamic characteristics of the rolling process. Therefore, product quality and yield can be further improved.

<Second Invention> In the first embodiment described above, it is conceivable that the estimation accuracy of the damping coefficient is affected by insufficient power of the input / output signal to / from the looper position control device 7 in a stable rolling state. The second invention (and a fourth invention described later) was developed to eliminate this effect, and the second invention will be described below. As shown in FIG. 4, a controller 0 for a continuous rolling mill according to an embodiment (second embodiment) of the second invention.
_x is the position of the looper 3 that applies tension to the material 2 to be rolled that is rolled by the roller stands 1 and 1 arranged in tandem, detected by the looper angle detector 5, and the rollers of the stands 1 and 1 are detected based on this detection data. This is the same as the conventional example in that it has a control system for issuing a signal for correcting the speed to the speed controller 9 of the mill motor 8. However, in the second embodiment, the stability calculator 7a _x (corresponding to the first stability calculator) for calculating the stability of the looper position based on the detected data of the looper position, and the roller speed Parameter estimating device 7b for calculating the damping coefficient of the transfer function of the control system on the basis of the correction amount of P and the detection data of the looper position.
_x (corresponding to the first parameter calculation means), the damping coefficient calculated by the parameter estimation device 7b _x when the stability calculated by the stability calculation device 7a _x exceeds a threshold value, and An interpolation type PI controller 7c for setting the control gain of the control system based on a table of a plurality of control gains corresponding to a plurality of stored damping coefficients (corresponding to the correspondence relationship between the damping coefficient and the control gain).
_x (corresponding to the first control gain setting means) is different from the conventional example.

FIG. 5 is a block diagram showing a partial configuration of the second embodiment, showing the flow of control signals for controlling the looper position to the set position. Hereinafter, the second embodiment device 0
The operation of _x and its basic principle will be described with reference to FIGS. In FIG. 4, an appropriate torque is applied to the looper 3 by the looper motor 4 so that the tension of the rolled material 2 between the stands 1 and 1 becomes an appropriate value. Looper height, and the looper position detected by the looper angle detector 5, on the basis of a deviation between the looper setting position set by the looper locator 6, stability calculation device 7a _x at looper position controller 7 _x, parameter The estimation device 7b _x and the interpolating PI controller 7c _x are controlled to correct the rolling speed (corresponding to the roller speed) of the adjacent stand. Here, the stability calculation device 7a _x , the parameter estimation device 7b _x, and the interpolation type PI, which are the features of the second invention,
The controller 7c _x will be described in detail.

[Stability Calculator 7a _x ] The stability calculator 7a _x calculates the stability of the looper angle (corresponding to the looper position) using the following equation.

[Equation 4] Here, J [•] is the stability of the looper angle, y [•] is the looper angle, k is the number of steps, λ is the forgetting coefficient, and ‖ · ‖ is the absolute value. This index corresponds to the integral of the magnitude of acceleration of the looper angle. The reason for using the acceleration information in this way is to ignore only the bias and the gradual trend from the variation of the looper angle and extract only the oscillating component. If the calculation result of the stability calculation device 7a _x is smaller than the threshold value, the control system is considered to be stable, and a static control gain stored in advance is set. The control gain of the control system is dynamically set based on the damping coefficient calculated by the estimation device 7b _x and the table of the plurality of control gains corresponding to the plurality of damping coefficients stored in advance.

[Parameter Estimator 7b _x ] The parameter estimator 7b _x calculates the damping coefficient from the speed correction amount of the mill motor 8 and the online data of the looper angle by using the recursive least squares method. For example, in the case of a hot finishing mill for iron and steel, it has been known from analysis of actual machine data that the control system (looper height system) can be modeled by a transfer function of second-order lag + dead time. For this analysis, the AR
MA analysis is used. For this reason, first, three parameters represented by the following equation obtained by discretizing the transfer function are estimated, and then the damping coefficient is calculated using the estimated values.

(Equation 5)

(Equation 6)

Where p ₁ , p ₂ and p ₃ are parameters to be estimated y [•] is the looper angle, u [•] is the mill motor speed correction amount, k is the number of steps, L is dead time, and T is sampling. Interval, {•} is Gaussian symbol, and ζ is damping coefficient. Before the rolled material 2 reaches the continuous rolling mill, the variation range of the damping coefficient is grasped by the parameter estimation device 7b _x in advance, and the control is performed when the damping coefficient takes several values within the variation range. The control gains of the proportional action element and the integral action element of the system are calculated and stored as a table in a memory (not shown). [Interpolation type PI controller 7c _x ] If the stability calculated by the stability calculating device 7a _x during rolling is less than a threshold value, control of static proportional motion elements and integral motion elements stored in advance The gain is used for control to calculate the speed correction amount of the mill motor 8 required so that the position of the looper 3 becomes the set position. If the stability is equal to or higher than the threshold value, the damping coefficient calculated by the parameter meter estimation device 7b _x and the control gains of the proportional operation element and the integral operation element of the table stored in the memory in advance are set. Based on this, the operations of the proportional action element and the integral action element used for control are calculated by linear interpolation, and the speed correction amount of the mill motor 8 necessary to bring the position of the looper 3 to the set position is calculated. A correction signal is sent to the speed controller 9 of the mill motor 8 by the interpolation type PI controller 7c _x , and the position of the looper 3 is stably set to the set position via the length of the rolled material 2 between the stands 1 and 1. Feedback control is performed so as to maintain the return.

The following is the result of a simulation performed using the apparatus 0 _x of the second embodiment as described above. FIG. 6 shows simulation results assuming a steel hot-finishing continuous rolling mill. In FIG, (b), (d) are those of the conventional control device 0 'indicates the (a), (c) the control performance of the second embodiment device 0 _x. As described above, in the second embodiment, it is understood that the control performance excellent in stability and responsiveness is maintained even if the characteristics of the control system are changed as compared with the conventional example. That is, in the second embodiment, the stability is calculated and the control method is switched according to the stability.
It is possible to avoid destabilization due to inaccuracy of damping coefficient that occurs during stable rolling of input and output signals (in stable rolling, accurate parameter estimation may not be possible due to insufficient signal power), and multiple dampings can be avoided. Control gain can be set finely by having a gain table corresponding to the coefficients. As a result, according to the second embodiment, there is provided a controller for a continuous rolling mill capable of always maintaining a stable control system and realizing looper control capable of high-speed response regardless of changes in dynamic characteristics of the rolling process. The quality and yield of products can be further improved.

<Third invention> Although the first and second embodiments are examples of the control device for the continuous rolling mill, the feedback control device for controlling the height and the position has the same structure. Many take. The third invention is made about such a control device, and the third invention will be described below. As shown in FIG. 7, a control device 10 according to an embodiment (third embodiment) of the third invention includes a parameter estimation device 12 (second device) for calculating a parameter of a transfer function of a control system including a controlled object 11. Of the control system), a parameter calculated by the parameter estimation device 12, and a table representing a correspondence relationship between a parameter such as an attenuation coefficient and a control gain, which is stored in advance. Interpolation type PI to set the gain
Controller 13 (corresponding to second control gain setting means)
It is composed of The operation and the basic principle of the third embodiment apparatus 10 of the first, is the same as the second embodiment device 0,0 _x. Therefore, according to the third embodiment, the fluctuation is particularly large among the fluctuations of the frequency characteristic of the control system,
By considering the fluctuation of the parameters that affect the stability of the control system, it is possible to realize the control of the height and position such as the looper height, which has good response characteristics and excellent stability.

<Fourth Invention> In each of the first to third embodiments, a so-called interpolation control for setting a control gain is performed by linearly interpolating a plurality of pre-stored attenuation coefficients. . On the other hand, in the fourth invention, the control gain is set by applying the well-known adaptive control technique. The fourth invention will be described below. As shown in FIG. 8, the controller 0 _y of the continuous rolling mill according to one embodiment (fourth embodiment) of the fourth aspect of the invention comprises roller stands 1, 1 arranged in tandem.
The looper angle detector 5 detects the position of the looper 3 that applies a tension to the material 2 to be rolled by, and the speed controller of the mill motor 8 outputs a signal for correcting the roller speed of the stands 1 and 1 based on the detected data. This is the same as the conventional example in that it has a control system originating from No. 9. However, in the fourth embodiment, the stability calculator 7a for calculating the stability of the looper position based on the detection data of the looper position.
A parameter estimating device 7b _y (third part) which calculates a parameter of the transfer function of the control system based on _y (corresponding to second stability calculating means), the correction amount of the roller speed, and the detection data of the looper position. Equivalent to the parameter calculation means of
And when the stability calculated by the stability calculating device 7a _x exceeds a threshold value, the parameter estimating device 7
and an adaptive controller 7c _y (corresponding to a third control gain setting means) for setting the control gain of the control system online on the basis of the dynamic characteristic of the transfer function using the parameter calculated by b _y . The point is different from the conventional example.
Furthermore, a so-called partial model matching method may be used to set the control gain, which is also different from the conventional example.

FIG. 9 is a block diagram showing a partial configuration of the fourth embodiment, showing the flow of control signals for controlling the looper position to the set position. Hereinafter, the device 0 of the fourth embodiment
The operation of _y and its basic principle will be described with reference to FIGS. In FIG. 8, an appropriate torque is applied to the looper 3 by the looper motor 4 so that the tension of the rolled material 2 between the stands 1 and 1 has an appropriate value. The looper height is based on the deviation between the looper position detected by the looper angle detector 5 and the looper set position set by the looper position setter 6, and the stability calculation device 7a _y and parameter estimation in the looper position control device 7 _y are performed. The device 7b _y and the adaptive controller 7c _y are controlled to correct the rolling speed (corresponding to the roller speed) of the adjacent stand.
Here, the stability calculation device 7a, which is a feature of the fourth invention,
_y, the parameter estimation device 7b _y and adaptive controller 7
_cy will be described in detail.

[Stability Calculator 7a _y ] The stability calculator 7a _y calculates the stability of the looper angle (corresponding to the looper position) using the following equation.

(Equation 7) Here, J [•] is the stability of the looper angle, y [•] is the looper angle, k is the number of steps, and λ is the forgetting function ‖ · ‖ is an absolute value. This index corresponds to the integral of the magnitude of acceleration of the looper angle. The use of acceleration information in this way is
This is because bias and gentle trends are ignored in the variation of the looper angle, and only oscillatory components are extracted.
If the calculation result of the stability calculation device 7a _y is smaller than the threshold value, the control system is considered to be stable, and a static control gain stored in advance is set.
The control gain of the control system is dynamically set based on the transfer function calculated by the parameter estimation device 7b _y . That is, the stability calculation device 7a _y performs the same operation as the stability calculation device 7a _x in the second embodiment.

[Parameter Estimator 7b _y ] The parameter estimator 7b _y uses the recursive least squares method to determine the parameters of the transfer function between these data from the speed correction amount of the mill motor 8 and the online data of the looper angle. Calculate For example, in the case of a hot finishing mill for iron and steel, it has been found from analysis of actual machine data that the control system (looper height system) can be modeled by a transfer function of second-order delay + dead time, and the dead time is constant. Therefore, the damping coefficient, the resonance frequency, and the steady gain, which are the parameters of the second-order lag part, are estimated. This analysis also uses the AR
MA analysis is used. Therefore, we first estimate the three parameters expressed by the following equation, which are obtained by discretizing the transfer function,
Then, using these estimated values, the damping coefficient, resonance frequency, and steady gain are calculated.

[Equation 8]

[Equation 9]

[0028]

[Equation 10]

[Equation 11] Here, p1, p2, p3 are parameters to be estimated, y
[•] is the looper angle, u [•] is the mill motor speed correction amount, k is the number of steps, L is the dead time, T is the sampling interval, {•} is the Gauss symbol, ζ is the damping coefficient, and w _n is the resonance frequency. , K ₁ are stationary gains. [Adaptive controller 7c _y ] If the stability calculated by the stability calculating device 7a _y during rolling is less than a threshold value, control gains of static proportional action elements and integral elements stored in advance are controlled. Is used to calculate the speed correction amount of the mill motor 8 required so that the position of the looper 3 becomes the set position. Moreover, the stability parameters and proportional action elements and integrated operation of the I-P controller is determined using known partial model matching method of the transfer function calculated by said parameter estimating unit 7b _y if more threshold The control gain of the element is used for control, and the speed correction amount of the mill motor 8 required to bring the position of the looper 3 to the set position is calculated.

Here, the partial model matching method means the following method (see Toshiyuki Kitamori, "Design of control system", published by Ohmsha). (1) When the controlled object is represented by the impulse response moment series, the low-order moments play a dominant role in determining the shape of the response curve. (2) If the reciprocal of the transfer function of the controlled object is Maclaurin expanded around the operator S = 0 and expressed by the following equation, all the information included in the moment up to the i-th order is included in the parameters C ₀ , ... C _i .

[Equation 12] (3) The partial model matching method uses the above properties,
The parameters C ₀ , ... C _i of the target control system are matched with desired values (for example, {1, 1, 0.5, 0.15, ...} are said to be desirable). In other words, it is to adjust only the low-order moment to a desired value. (4) According to this partial model matching method, since the knowledge of the controlled object is not used completely, the modeling may fail, but the control gain does not depend on the order of the controlled object. It can be calculated analytically.

The structure of the adaptive controller 7c _y is always as shown in FIG. 10, and only the control gain changes. The adaptive controller 7c _y by the corrected signal to the speed controller 9 of the mill motor 8 is sent, the position of the looper 3 via the length of the rolled material 2 between each stand 1, 1 return held stably to its set position Feedback control is carried out so as to The flow of this operation is shown in FIG. FIG. 12 shows the result of simulation performed using the device 0 _y of the fourth embodiment as described above. FIG. 12 is a simulation result assuming a steel hot finishing continuous rolling mill. In the figure, (a) shows the control performance by the conventional control device 0 ', while (b) shows the control performance by the fourth embodiment device _0y . As described above, in the fourth embodiment, it can be seen that the control performance excellent in stability and responsiveness is maintained even if the characteristics of the control system fluctuate as compared with the conventional example.

That is, in the fourth embodiment, since the stability is calculated and the control method is switched according to the stability, the accuracy of the parameter of the transfer function that occurs in the stable rolling of the input / output signal (stable rolling is stable). However, instability due to inaccurate parameter estimation may not be possible due to insufficient signal power). This point is similar to the second embodiment. In addition, when the stability of the control system is deteriorated due to the fluctuation of the frequency characteristic of the control system, the response function is excellent and the looper height is also excellent by the dynamic consideration of the transfer function of the control system. Control can be realized. as a result,
According to the fourth embodiment, there is provided a control device for a continuous rolling mill capable of always maintaining a stable control system and realizing looper control capable of high-speed response regardless of changes in dynamic characteristics of a rolling process. The product quality and yield can be further improved. <Fifth Invention> In the first to third embodiments, interpolation control is used, and in the fourth embodiment, adaptive control is used. Among them, adaptive control is premised on accurately grasping the system characteristics online, but when online is difficult, control performance deteriorates rather. Therefore, in such cases, interpolation is required. Control is preferable.

That is, the interpolation control is intended to be implemented simply at the expense of theoretical perfection. However,
The "sacrifice of theoretical perfection" is practically acceptable. Normally, this interpolation control is based on the premise that the standard gain of control is given in advance. However, considering the characteristic changes of the controlled object, the control gain must be adjusted periodically. The fifth invention was made by paying attention to this point, and the fifth invention will be described below. As shown in FIG. 13, the control device 20 according to one embodiment (fifth embodiment) of the fifth invention is controlled by a control target 21.
A parameter estimating device 22 (corresponding to a fourth parameter calculating means) for calculating a parameter of a transfer function of a control system including the controlled object 21 based on the input / output data to and the parameter calculated by the parameter estimating device 22. , An interpolation type PI controller 23 that sets the control gain of the control system by performing an interpolating operation based on a table representing the correspondence relationship between the parameters stored in advance and the control gain (corresponding to a fourth control gain setting means) An interpolation frequency calculation device 24 (corresponding to interpolation frequency calculation means) for calculating the frequency of interpolation calculation due to hunting of the control system when setting the control gain by the interpolation PI controller 23; and the interpolation frequency calculation device. A table for changing the stored contents of the table according to the frequency of the interpolation calculation calculated by 24. Is constructed from a storage content changing device 25 (corresponding to the correspondence changing means).

The operation of the device of the fifth embodiment and its basic principle will be described in detail below. Although the control of the continuous rolling mill is described here as an example, as described above, the fifth embodiment apparatus is a feedback control system controller that controls the height and position, except for control of the continuous rolling mill. It is also applicable to. Generally, the control gain of the PI controller is
(1) Higher is preferable from the viewpoint of quick response.
(2) When the control gain is increased, the stability is lost.
It is necessary to make a decision in consideration of two competing criteria. It is difficult to determine the control gain of the looper position control system even if one coil, which is the material to be rolled, is rolled.
Material properties, environmental conditions (plate temperature, plate composition, rolling speed, etc.)
That is, the characteristics of the process vary. Therefore, during rolling, the control gain of the controller becomes relatively high, and the control system of the looper position suddenly becomes unstable, and the looper begins to behave in an oscillatory manner called hunting as shown in FIG. 14 (a). Sometimes. Due to the occurrence of this hunting, the parameter estimation value also changes as shown in FIG. J in the figure is the stability of the equation (4),
p ₁ , p ₂ and p ₃ are the estimation parameters of the equations (1) and (5). When such an unstable phenomenon occurs, the control gain of the controller is generally lowered. However, such a gain adjustment is performed only in the direction of lowering the control gain, so that the control gain is decreasing as a whole, which causes a problem that the quick response is deteriorated.

Here, the following two points are indispensable for proper newning of the control gain. (1) Accurate model of target process (2) Norm for gain norm The following method has been conventionally used as a gain tuning method. (1) As a gain adjustment reference, a preferable reference model is set in advance (for example, pole position). (2) The model of the controlled object is identified online, and the parameters of the control system are adjusted so that the control system matches the reference model (for example, the poles are located at predetermined positions). Practically, such a method has the following problems. (1) In order to identify the model of the target process, it is necessary to input a signal containing a sufficient number of frequencies with sufficient power to the control system (sufficient rich condition). However, in actual operation, the steady ric
It is not possible to obtain an input signal such as h and input it for identification. This is because it becomes a disturbance of the operation. Therefore,
It is difficult to always secure an accurate process model.

(2) The disturbance applied to the control system also becomes a disturbance for system identification. There is also a trade-off between stability of system identification and quick response, which creates a new adjustment problem in addition to adjusting the control gain. (3) In the transient state of system identification, the control gain also changes transiently, but it is difficult to ensure the stability in such a transient state. This is because the transient state is a disturbance to the operation. (4) Depending on how to select the reference model, the order of the controller becomes high, design and adjustment become difficult, and it becomes difficult to secure stability in calculation. For example, a richer input signal is required, and it becomes vulnerable to disturbance. In consideration of these problems, the interpolation control as in the first to third embodiments is a method that balances the ease of realization and the adaptive function. Here, (1) Representative control parameters are prepared in advance as a table for a plurality of situations. (2) Judge which of the situations in the above table the current situation is similar to, and select appropriate control parameters. Alternatively, a plurality of control parameters are interpolated according to the degree of similarity.

Therefore, these methods have the following advantages. (1) It is possible to prevent the control parameter from being excessively disturbed by the system identification error (determined only within the range of the control parameter prepared in advance). (2) Since not all the parameters of the target model are identified, the number of variables to be identified is reduced, and thus the estimation accuracy and estimation stability are improved. However, the problems are: (3) Transient state (while control parameters are changing)
The characteristics of the control system as a whole are not constant. However,
This problem is not so important because the transient state is short in time. Further, the effect of the above-mentioned interpolation control is that "the control gain is automatically weakened and hunting is suppressed in the initial stage where hunting occurs". The effect is shown in FIG. In the interpolation PI control, as shown in FIG. 15A, since hunting is almost suppressed in the initial stage, human eyes hardly notice hunting. On the other hand, in the conventional PI control, large hunting is seen as shown in FIG.

The feature of the fifth invention is that the gain is increased based on the above-mentioned interpolation control in order to improve such a gain adjusting method for decreasing the gain. The outline of the fifth invention can be intuitively explained as follows. (1) If the control gain is too high and hunting occurs, the interpolation control operates and holds it down, so the control gain can be increased with confidence. (2) However, the reason why the interpolation control frequently operates is that the control gain is too high. (3) Therefore, for each steel type (for example, the coils are classified by finish thickness, width, and strength), how often the interpolation control is operated is monitored. (4) If the operation frequency is lower than the predetermined threshold value at the present moment, the control gain is increased at a certain ratio. On the contrary, if the operation frequency is higher than the predetermined threshold value, the control gain is lowered at a certain frequency. Here, it is assumed that the transfer function of the controller is given by Kp (1+ (1 / Ti) (1 / s)) (PI control). Where Kp, Ti
Is a control parameter. The gain tuning here is determined by multiplying Kp by certain constants g and h.

(1) Now, it is assumed that the reference gains (gains normally used) Kp and Ti for each steel type are given. (2) It is also assumed that g = 1.05 h = 1 / g. (3) Let r be the operation frequency of the interpolation operation in the past one month (parameter x1). The value of this operation frequency r is automatically calculated. At this time, control gain is tuned by the following logic. (1) If the operation frequency r is 5% or less (parameter X2), the reference gain Kp is multiplied by a constant g. (2) If the operation frequency r is 10% or more (parameter X3), the reference gain Kp is multiplied by a constant h. Such tuning is performed once a week (parameter X4). Here, the following parameters shall be adjusted by the user according to the situation. (1) Constants g and h for increasing control gain / phenomenon (2) Parameter X1 for determining the range of data for calculating the operation of interpolation control (3) Increasing control gain, actuation frequency r that triggers the phenomenon Threshold parameters X2, X3 (4) Parameter X4 that determines the adjustment interval

As described above, according to the fifth embodiment, by automatically adjusting the control gain including the increase thereof within the range where the stability can be secured, the response characteristic is excellent and the stability is excellent. It is possible to realize height and position control. <Modification> In each of the first, second, third and fifth embodiments described above, a PI type controller is used as the base controller, but a PID type controller may be used instead. Hereinafter, such a modified example will be briefly described. Now, assume that the transfer function of the controller is given by Kp (1+ (1 / Ti) (1 / s) + Tds) (PID control). Where Kp is P
ID gain, Ti is an integration time constant, Td is a differential time constant, and a plurality of sets of them are prepared. For example, here
Prepare a pair. Set 1: PS1 = (Kp ¹ , Ti ¹ , Td ¹ ) Set 2: PS2 = (Kp ² , Ti ² , Td ² ) Of these, Set 1 (PS1) is the control gain that is normally used, and Set 2 (PS2 ) Is P in set 1 (PS1)
50% less ID gain (Kp ² = 0.5K
p ¹ ).

When hunting occurs, the control gain may be switched from set 1 (PS1) to set 2 (PS2). The interpolation control may be performed as follows. At this time, the PID gain is given by the following equation. Kp ^ = (1-γ) Kp 1 + γKp 2, represents a transition degree of the (0 <γ <1) ... (8) Here, Kp ^ interpolation calculation value of the PID gain, gamma normal state and hunting state It is a parameter. In the first, second, third and fifth embodiments, the control parameter is determined based on the system identification result, but it is not always necessary to determine this parameter γ. For example, this parameter γ can also be determined based on the stability J of the equation (4). That is, as shown in FIG. 16, the parameter γ is determined for the value of the stability J,
As a result, the PID gain can be interpolated using the equation (8). As described above, in any of the embodiments, regardless of the change in the dynamic characteristics of the control system, the control system can always be kept stable, and the height and position control capable of high-speed response can be realized.

[0041]

Since the control devices according to the first to fifth aspects of the invention are configured as described above, they are always stable regardless of changes in the dynamic characteristics of the control system. In addition, it is possible to realize height and position control that enables high-speed response.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a control device 0 of a continuous rolling mill according to an embodiment (first embodiment) of the first invention.

FIG. 2 is an explanatory diagram showing an input / output relationship with a looper position control device 7.

FIG. 3 is a comparative diagram showing the control performance of each looper angle by the control devices 0 ′ and 0.

FIG. 4 is a schematic diagram showing a schematic configuration of a control device 0 _x of a continuous rolling mill according to an embodiment (second embodiment) of the second invention.

FIG. 5 is an explanatory diagram showing an input / output relationship with a looper position control device 7 _x .

[6] The control unit 0 'and comparative diagram showing the control performance of each looper angle by 0 _x.

FIG. 7 is a schematic diagram showing a schematic configuration of a control device 10 according to an embodiment (third embodiment) of the third invention.

FIG. 8 is a schematic diagram showing a schematic configuration of a control device 0 _y of a continuous rolling mill according to an embodiment (fourth embodiment) of the fourth invention.

FIG. 9 is an explanatory diagram showing an input / output relationship with the looper position control device 7 _y .

FIG. 10 is a block diagram of an IP control system.

FIG. 11 is a flowchart showing an operation procedure by the control device 0 _y .

FIG. 12 is a comparative diagram showing the control performance of each looper angle by the control devices 0 ′ and 0 _y .

FIG. 13 is a schematic diagram showing a schematic configuration of a control device 20 according to an embodiment (fifth embodiment) of the fifth invention.

FIG. 14 is an explanatory diagram showing an example of hunting.

FIG. 15 is an explanatory diagram showing the effect of interpolation control.

FIG. 16 is an explanatory diagram showing a parameter interpolation method in a modified example.

FIG. 17 is a schematic configuration diagram of a looper facility.

FIG. 18 is a schematic diagram showing a schematic configuration of an example of a control device 0 ′ of a conventional continuous rolling mill.

FIG. 19 is a block diagram of a PI controller.

[Explanation of symbols]

0 ... Control device for continuous rolling mill according to the first invention 1 ... Roll stand 2 ... Rolled material 3 ... Looper 7a ... Parameter estimation device (corresponding to calculation means) 7b ... Interpolation type PI controller (corresponding to control gain setting means) ) 0 _x ... controller 7a _x ... stability arithmetic unit continuous rolling mill according to a second aspect of the present invention (corresponding to a first stable calculating means) 7b _x ... parameter estimation device (corresponding to a first parameter calculating means) 7c _x ... Interpolation type PI controller (corresponding to first control gain setting means) _0x ... Controller for continuous rolling mill according to the second invention 7a _x ... Stability calculation device (corresponding to first stability calculation means) ) 7b _x ... parameter estimation device (corresponding to a first parameter calculation means) 7c _x ... interpolative PI controller (corresponding to a first control gain setting means) 10 ... control device 11 ... control pairs of the third invention 12 ... parameter estimation device (second corresponds to the parameter calculation means) 13 ... interpolative PI controller (corresponding to the second control gain setting means) 0 _y ... fourth control apparatus 1 ... roll continuous rolling mill according to the invention stand 2 ... the rolled material 3 ... looper 7a _y ... stability processing unit (second corresponds to stability computing means) 7b _y ... parameter estimation device (corresponding to the third parameter arithmetic unit) 7c _y ... interpolative PI controller (Corresponding to third control gain setting means) 20 ... Control device according to fifth invention 21 ... Control object 22 ... Parameter estimating device (corresponding to fourth parameter calculating means) 23 ... Interpolation type PI controller (fourth) Control gain setting means) 24 ... Interpolation frequency calculation device (corresponding to interpolation frequency calculation means) 25 ... Table storage content changing device (corresponding to correspondence relationship changing means)

Claims (18)

[Claims] 1. A continuous rolling system provided with a control system for detecting the position of a looper which applies a tension to a material to be rolled by a roller stand arranged in tandem, and correcting the roller speed of the stand based on the detected data. A controller of the machine, computing means for computing the damping coefficient of the transfer function of the control system based on the correction amount of the roller speed and the detection data of the looper position; and the damping coefficient calculated by the computing means, A control device for a continuous rolling mill, comprising: control gain setting means for setting a control gain of the control system based on a maximum value and a minimum value of a damping coefficient stored in advance. 2. The control device for a continuous rolling mill according to claim 1, wherein the transfer function comprises a second-order lag element and a dead time element. 3. The control device for a continuous rolling mill according to claim 1, wherein the control gain of the control system includes a proportional operation element and an integral operation element. 4. The control device for a continuous rolling mill according to claim 1, wherein a recursive least squares method is used for calculating the damping coefficient by the calculating means. 5. Continuous rolling provided with a control system for detecting the position of a looper which gives a tension to a material to be rolled by a roller stand arranged in tandem, and correcting the roller speed of the stand based on the detected data. In a controller of the machine, based on first stability calculation means for calculating stability of the looper position based on the detection data of the looper position, correction amount of the roller speed and detection data of the looper position. A first parameter calculating means for calculating a damping coefficient of a transfer function of the control system; and a stability calculated by the first stability calculating means exceeding a threshold value,
A first setting of the control gain of the control system based on the damping coefficient calculated by the first parameter calculating means and the correspondence relationship between the damping coefficient and the control gain stored in advance.
A control device for a continuous rolling mill, comprising: 6. The control device for a continuous rolling mill according to claim 5, wherein the transfer function includes a second-order lag element and a dead time element. 7. The control device for a continuous rolling mill according to claim 5, wherein the control gain of the control system includes a proportional operation element and an integral operation element. 8. A recursive least squares method is used for calculating the damping coefficient by the first parameter calculating means.
A control device for a continuous rolling mill according to any one of 1. 9. A second parameter calculating means for calculating a parameter of a transfer function of a control system including the controlled object based on input / output data for the controlled object, and a parameter calculated by the second parameter calculating means. A control device comprising: a second control gain setting means for setting a control gain of the control system based on a correspondence relationship between a parameter and a control gain stored in advance. 10. Continuous rolling provided with a control system for detecting the position of a looper which gives a tension to a material to be rolled by a roller stand arranged in tandem and correcting the roller speed of the stand based on the detected data. Second stability calculation means for calculating stability of the looper position based on the detection data of the looper position,
Third parameter calculating means for calculating the parameter of the transfer function of the control system based on the correction amount of the roller speed and the detected data of the looper position, and the stability calculated by the second stability calculating means. Third control gain for setting the control gain of the control system online based on the dynamic characteristics of the transfer function using the parameter calculated by the third parameter calculation means when the value exceeds the threshold value. A control device for a continuous rolling mill, comprising: setting means. 11. The control device for a continuous rolling mill according to claim 10, wherein the dynamic characteristic of the transfer function includes a second-order lag element and a dead time element. 12. The control device for a continuous rolling mill according to claim 10, wherein the control gain of the control system includes a proportional operation element and an integral operation element. 13. The control device for a continuous rolling mill according to claim 10, wherein the control system is an IP control system. 14. The control device for a continuous rolling mill according to claim 10, wherein a recursive least squares method is used for the calculation of the transfer function parameter by the third parameter calculation means. 15. The control device for a continuous rolling mill according to claim 10, wherein a partial model matching method is used for setting the control gain by the third control gain setting means. 16. A fourth parameter calculating means for calculating a parameter of a transfer function of a control system including the controlled object based on input / output data for the controlled object, and a parameter calculated by the fourth parameter calculating means. , A fourth control gain setting means for setting a control gain of the control system by performing an interpolating operation based on a correspondence relationship between a parameter stored in advance and a control gain, and control by the fourth control gain setting means Correspondence between the parameter and the control gain in accordance with the interpolation frequency calculation means for calculating the frequency of the interpolation calculation due to the occurrence of hunting in the control system when setting the gain, and the frequency of the interpolation calculation calculated by the interpolation frequency calculation means. A control device comprising: correspondence changing means for changing a relationship. 17. The control gain is increased when the frequency of the interpolation calculation calculated by the interpolation frequency calculation means is smaller than a predetermined upper limit value, and the control gain is decreased when the frequency is larger than a predetermined lower limit value. 17. The control device according to claim 16, wherein the control gain is set by the fourth control gain setting means as described above. 18. The control device according to claim 16, wherein the correspondence relationship between the parameter and the control gain is stored in advance in a memory for each type of the controlled object.