JPH09192716A - Looper multi-variable controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute a stable operation by using a two-input and two-output system wherein controlled variable are specified to be a tension of stock to be rolled and a quantity added a value multiplied the tension by a weight parameter to a looper angle and manipulated variable are specified to be a velocity revising command value for a main motor for rolling and a velocity command value for a looper motor. SOLUTION: Based on a model 13 of controlled system process, in a setting means 14, the objective tension value of rolling stock 1, the objective value of looper angle, variables or the like expressing the model of the controlled system process, and the quantity added the tension of rolling stock multiplied by the weight parameter to the looper angle besides the tension of rolling stock as the controlled variable are adopted, and the weight parameter values are respectively set. In an control and arithmetic unit 12, respective set variables are substituted into a control gain formula to obtain the control gain as a numerical value, the velocity correction command value for the main motor 10 for rolling and the velocity command value for the looper motor 7 are calculated using the control gain.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a looper multivariable controller for controlling the height of a looper arranged between stands of a tandem rolling mill and the tension between stands of a rolled material.

[0002]

2. Description of the Related Art Sheet thickness and sheet width are part of the evaluation criteria for final products in hot rolling and cold rolling. Among these, the automatic plate thickness control is performed on the plate thickness, and the automatic plate width control is performed on the plate width. On the other hand, the tension applied to the material being rolled affects the plate thickness and the plate width, so tension control is performed.

In particular, the rolled material in hot rolling is heated to a high temperature to reduce the deformation resistance of the rolled material. If the tension is large, the material is likely to break. If the tension is set low to prevent this breakage, there may be a tensionless state due to disturbance or erroneous setting, and if that state continues for a long time, a large loop may occur between the rolling mill stands, resulting in an accident. is there. Therefore, in the hot rolling mill, a looper device is provided in particular, the tension control is performed by this looper device, and the height of the looper is controlled from the viewpoint of improving the sheet passing property of the material.

In such a rolled material tension and looper height control device, there are interference from the rolled material tension to the looper height and interference from the looper rotation speed to the tension. For the conventional tension control, a method of controlling the rolling material tension and looper height by PID control without suppressing the interference, and a decoupling compensator for suppressing these interferences are added to the rolling material tension control. There is a non-interference control method that controls the looper height independently, or a method that regards the interference system of the looper and rolling material tension as a multivariable system and applies the optimal control theory (Linear Quadratic). ing.

[0005]

In the above-mentioned method using PID control, since there is no function of suppressing the mutual interference between the rolled material tension and the looper, the responsiveness and stability are lacking. Therefore, recently, non-interference control and optimum control are widely used.

Among these, in the decoupling control, as an example for realizing a decoupling device such as a cross controller, a transfer function of the decompensation device for decoupling is realized on a computer. . In general, this transfer function has a high order, and therefore, the adverse effect of the mismatch between the actual plant and the model may be remarkable, or the calculation accuracy on a computer may be problematic. Also, as the original function of the looper, the looper should move to suppress the fluctuation of tension and play a part of the tension control, but the looper height is controlled to be constant by decoupling, so the looper does not work sufficiently. Wasn't put to good use.

On the other hand, in the method based on the optimal control theory, the control gain can be designed so that the rolling main motor and the looper are used in cooperation as the operating end. In this optimum control, it is difficult to find the causality between the weighting matrices Q and R in the evaluation function J shown in the following equation (1) and the response of the actual process, and Q, which realizes an appropriate response of the entire control system, It is general to find R by trial and error and determine the control gain.

[0008]

[Equation 1] Here, x is the state quantity of the controlled process u: the operation amount given to the controlled process by the controller x ^T : transposition of x u ^T : transposition of u

Since trial and error are repeated in this way, much time is required for designing the control system and adjusting the plant. In addition, in the method based on this optimal control theory, since it is necessary to numerically solve the Riccati equation that cannot be solved analytically, there is a case where the general formula of the optimal control gain including variables cannot be obtained.

To use the gain table without obtaining the general formula, the gain table is prepared in advance by obtaining the control gain that matches the properties of the rolling material and the rolling conditions, and the table is referred when the control gain is used. The method is generally used. Therefore, much time and effort are required to determine, maintain, and manage the values of this gain table.

Further, it is almost impossible to describe all cases in the gain table, and under the rolling condition or the like that does not exist in the gain table, the gain must be approximated from a table similar to the rolling condition or the like. The control performance may be degraded.

On the other hand, as a variation of the optimal control theory, I
There is LQ (Inverse Linear Quadratic) control. This is a method in which it is not necessary to solve the Riccati equation while satisfying the condition of optimality, and the control gain is obtained as a mathematical expression instead of a numerical value by applying the premise of decoupling the input and output. If the control gain is obtained by a mathematical expression, the drawbacks of the method based on the above-mentioned optimal control theory are solved, but since this is premised on decoupling, the above-described decoupling control of the decoupling control that the looper function is not fully utilized. The drawbacks still remain.

In addition, the control object model of the looper control system which has been used conventionally has a degree of 5 or more, which is generally defined by the number of internal state variables, and can be used for design and adjustment even if ILQ control theory or the like is used. It had the drawback of being time consuming.

The present invention has been made in order to solve the above-mentioned problems, and a multivariable system is used as an interference system of the height of a looper arranged between stands of a tandem rolling mill and the tension between stands of a rolled material. It is an object of the present invention to provide a looper multi-variable control device that enables optimum control of the looper and the rolling material tension when controlled as.

[0015]

According to the present invention, as a model of an interference system between a looper height of a tandem rolling mill and a rolled material tension, a controlled variable is multiplied by the rolled material tension and the rolled material tension is multiplied by a weighting parameter. A two-input two-output system in which the operation amount is added to the angle, and the operation amount is the speed correction command value of the rolling main motor and the speed command value of the looper motor, and rolling material tension, looper angle, and looper motor speed are internal state variables. Among them, the one that includes at least the rolled material tension and the looper angle is used, while the setting means sets the target value of the rolled material tension, the target value of the looper height, the variable expressing the model of the process to be controlled, the rolled material tension and the looper height. When a variable for designating the response of the rolling stock, a variable for adjusting the response of the rolled material tension and the looper height, and a weight parameter are set, the control calculation means sets the setting means. Substituting the set value set in the control gain formula corresponding to the model, the control gain is obtained as a numerical value, using this control gain to calculate the speed correction command value of the rolling main electric motor and the speed command value of the looper electric motor, Add the calculated speed correction command value to the speed control system of the rolling traction motor,
The speed command value is added to the speed control system of the looper motor, which allows the Riccati equation to be numerically solved for changes in the state of the rolled material or the operating state, or to use a control gain table. In addition, since the rolling main motor and the looper motor work in cooperation to control the rolling material tension, the rolling material tension and the looper height can be optimally controlled.

When the model of the process to be controlled has the rolled material tension and the looper angle as internal state variables, the control calculation means multiplies the rolled material tension by the first feedback gain and the speed of the speed control system of the rolling traction motor. The correction amount of the correction command value is used as the correction amount for the speed correction command value of the speed control system of the rolling main motor by multiplying the looper angle by the second feedback gain, and the looper angle is multiplied by the third feedback gain as the correction amount of the looper motor. This is the correction amount for the speed command value of the speed control system.

When the model of the process to be controlled uses the rolled material tension, the looper angle and the looper motor speed as internal state variables, the control calculation means multiplies the rolled material tension by the first feedback gain and the speed of the rolling main motor. The correction amount of the speed correction command value of the control system is used, and the second feedback gain is multiplied by the looper angle to obtain the correction amount and amount of the speed command value of the speed control system of the looper motor, and the third feedback gain is added to the looper motor speed. It is multiplied by this to be the correction amount of the speed command value of the speed control system of the looper motor.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on preferred embodiments. FIG. 1 is a block diagram showing a schematic configuration of a first embodiment of the present invention together with an applicable rolling mill. In FIG. 1, the rolled material 1 is rolled in the order of an i-th stand rolling mill 2 and an (i + 1) th stand rolling mill 3. Here, when the total number of stands of the tandem rolling mill is n, n = 5 to 7 is general. A device such as a looper shown below is installed between the stands, but since it can be easily expanded to other stands by considering the state between the two stands i to i + 1, only the two stands will be considered here. Note that i is in the range of 1 ≦ i ≦ n−1.

A looper 4 is provided between the i-th stand rolling mill 2 and the (i + 1) th stand rolling mill 3. At this time, the tension of the rolled material received by the looper roll is detected by the tension detecting device 5. Further, the height of the looper converted into the angle of the looper arm is detected by the looper angle detection device 6 (hereinafter, the looper height is also referred to as the looper angle). A rotation speed detection device 8 is attached to the looper electric motor 7 that drives the looper 4, and the looper electric motor 7 is controlled by the looper electric motor speed control device 9 so as to reduce the deviation between the rotation speed of the looper electric motor and its rotation speed command value. It

On the other hand, the main machine speed control device 11 for controlling the speed of the rolling main electric motor 10 of the i-th stand (hereinafter, the rolling main electric motor is referred to as the main electric machine) has a main machine speed and a set speed set by a host computer or the like. To reduce the deviation from the speed command value corrected by the speed correction command value described later.
Controls the current of the stand main unit 10.

The speed command value of the looper electric motor 7 and the speed correction command value of the i-th stand main engine 10 described above are used as control calculation means 12
Is calculated by In this case, the model 13 of the controlled process
Based on the above, the setting means 14 sets the target value of the tension of the rolled material, the target value of the looper angle (height), the variable expressing the model of the process to be controlled, the variable for specifying the response between the inter-stand tension and the looper angle, and the stand. Variables for adjusting the response of the inter-tension and looper angle, and as the control amount, the rolled material tension is multiplied by a weighting parameter as well as the weighting parameter, and the amount is added to the looper angle. When set, the control calculation means 12 substitutes each set variable into a predetermined control gain formula to obtain the control gain as a numerical value.

FIG. 2 is a block diagram of a control system corresponding to the control system shown in FIG. 1 excluding the setting means 14. In FIG. 2, blocks 21 to 26 are processes to be controlled and correspond to elements denoted by reference numerals 1 to 11 in FIG. Among them, the main engine speed control system in FIG. 1 is not described as a block because the speed control response is sufficiently fast and is approximated by “1”. Block 21 is an influence coefficient from the main machine speed to the rolling material speed, and f represents an advanced rate. Block 22 is a tension generation gain and integrator in the tension generation process, block 23 is a feedback gain in the tension generation process, and the tension generation mechanism is modeled by blocks 22 and 23.
Block 24 is an influence coefficient from the looper rotation speed to the rolling material speed.

Further, a block 25 represents the speed control system of the looper motor by one block of the first-order lag response, and a block 26 is a transfer function from the rotation speed of the looper motor to the looper angle. The block 25 in FIG. 2 corresponds to the elements denoted by reference numerals 7, 8, and 9 in FIG.

Blocks 31 to 39 in FIG. 2 correspond to the control operation means 12 in FIG. 1, blocks 31 to 34 are integrators, and blocks 35 to 35 are blocks.
Up to 37 is a feedback controller. A block 38 is a tension control system response adjustment coefficient, and a block 39 is a looper angle control system response adjustment coefficient. In this case, the feedback controller 35 multiplies the rolled material tension by the feedback gain to obtain the correction amount of the speed correction command value of the main machine, and the feedback controller 36 multiplies the looper angle by the feedback gain to correct the speed command value of the looper motor. Then, the feedback controller 37 multiplies the looper motor speed by the feedback gain to obtain the correction amount of the speed command value of the looper motor.

Furthermore, in order to control both the looper angle and the rolled material tension in the looper height control system, the weight C ₁ in the block 40 is multiplied by the difference between the target value and the detected value of the rolled material tension to determine the looper angle target. In addition to the values, integral controllers 33 and 34
The amount of feedback to

When the controlled object process model shown in blocks 21 to 26 in FIG. 2 is written as a state equation, the following (2),
It becomes like the formula (3).

[0027]

[Equation 2] Here, “Δ” attached to the front of the symbol represents a minute change in the amount representing the symbol, and “·” attached to the symbol represents the time derivative. So, for example,

[0028]

(Equation 3) It is. Here, "t" represents time and "T" represents transposition. Vector display of state quantity x = [t _f ω θ] ^T Vector display of control amount y = [t _f θ] ^T Vector display of manipulated _variable u = [ΔV _RREF ω _REF ]
^{When the} equation of state is expressed as ^T , the following equation (4) is obtained.

[0029]

(Equation 4) Here, the dimensions of each matrix are 3 × 3 for A, 3 × 2 for B, and C.
Is 2 × 3, and these are shown in the following formula (5).

[0030]

(Equation 5) The meanings of the variables in the equation (5) representing the state equation are as follows. g _L : Gear ratio between looper and looper motor E: Young's modulus of rolled material t _f : Forward tension f: Advanced rate ω _L : Looper rotation speed F ₂ : Influence coefficient from looper rotation speed to rolling material speed K ₁₀ : Tension feedback coefficient L: Distance between stands V _R : Speed of main engine θ: Height of looper (expressed in angle) T _LS : Time constant of looper speed control system Subscript REF: Target value of the symbol.

Here, in order to control both the looper angle and the rolling material tension in the looper angle control system, the above equation (3) is modified as follows.

[0032]

(Equation 6) Here, the looper angle θ, which is one of the control amounts in the equation (3), is changed to y ₁ in the equation (7) by the equation (6). y ₁ = C ₁ t _f + θ (7) If the weight C ₁ in the equation (7) is increased, the specific gravity of the rolled material tension t _f is increased, and the rolled material tension itself is well controlled, but the looper angle θ Fluctuation increases. Further, if the weight C ₁ in the equation (7) is reduced, the specific gravity of the rolled material tension t _f is reduced, and the looper angle θ is controlled to be constant.
For example, if the weight C _{1 is set} to 0, the formula (3) known as the conventional process model is obtained.

A method of determining the control gain of blocks 31 to 37 in FIG. 2 corresponding to the control calculation means 12 of FIG. 1 will be described below. This method is basically determined using the ILQ method. The ILQ method is a solution of the LQ control problem from the viewpoint of an inverse problem. For example, the document "Generalization of the ILQ optimal servo system design method" (Takao Fujii, Taku Shimomura, Journal of the System Control Society, Vol. 1, NO. .6, 1988).

Blocks 31 to 37 are premised on decoupling the rolled material tension t _f and the looper angle y ₁ by using the model of the controlled process using the above equations (2) and (6). The control gain of can be expressed by the following equation. Block 31: K _IO 11 = −ω _TC · L / {E (1 + f)} (8) Block 32: K _IO 21 = −C ₁ · ω _TC · g _L · T _LS · (ω _HC −ω _TC ) ( 9) Block 33: K _IO 12 = 0 (10) Block 34: K _IO 22 = g _L · T _LS · ω _HC ² (11) Block 35: K _FO 11 = −L / {E (1 + f)} (12 ) Block 36: K _FO 23 = g _L · T _LS · ω _HC (13) Block 37: K _FO 22 = T _LS (14) where ω _{TC is} the cut-off frequency (rad / s) of the specified response of the tension control system. ) Ω _HC : Cutoff frequency (rad / s) of the designated response of y _{1 in} the equation (7), and designates desired values. Further, K _FO ik represents the feedback gain from the deviation between the command value and each element of the output vector to the i-th element u (i) of the input vector u, and K _IO ik represents the command value and each element of the output vector. Represents the integral gain from the deviation of to the i-th element u (i) of the input vector u. Note that K _FO 12, K _FO 13, and K _FO 21 are 0, so the description is omitted.

The control gains from Eqs. (8) to (14) are composed of variables of the target process model and mathematical expressions of response variables to be designated.

The adjustment coefficient σ ₁ is determined so that the tension control system has a desired response, and σ ₂ is determined so that the looper angle control system has a desired response. Generally, when σ ₁ and σ ₂ are set to large values, a fast response is obtained, but the main motor speed command value and the looper motor speed command value, which are manipulated variables, are also large values, so a too large value cannot be realized.
The control amount is set to two values, that is, a rolled material tension and an amount obtained by multiplying the rolled material tension by a weighting parameter and adding the looper angle.
~ The variables g _L , f, T _LS in the equation (14) are variables expressing the model of the process to be controlled, and ω _TC and ω _HC are variables for designating the response of the tension and the looper angle.
C ₁ is a weight parameter for multiplying the rolled material tension added to the looper angle as a control amount for the looper angle control,
Further, σ ₁ and σ ₂ in FIG. 2 are setting means 14 as variables for adjusting the responses of the inter-stand tension and the looper height, respectively.
Is set in the control calculation means 12. The control calculation means 12 substitutes these set values into the equations (8) to (14) and blocks.
The control gains of 31 to 37 are calculated and calculated as a numerical value together with the set values σ ₁ and σ ₂ .

Thus, according to the first embodiment, there is no need to numerically solve the Riccati equation or use a control gain table, and the main machine and the looper motor cooperate to determine the rolling material tension. Since it is controlled, the rolled material tension and the looper height can be optimally controlled.

FIG. 3 shows a second embodiment of the present invention, and is a block diagram of a control system corresponding to the control system shown in FIG. 1 except for the setting means 14. In FIG. 3, blocks 21 to 26 are processes to be controlled, and the configuration is different from that of FIG. 2 in that the speed control system of the looper motor is sufficiently fast and the block 25 is omitted. Blocks 41 to 46 in FIG. 3 correspond to the control calculation means 12 in FIG. 1, of which blocks 41 to 44 are integral controllers and blocks 45 to 46 are feedback controllers. In this case, the feedback controller 45 multiplies the rolled material tension by the feedback gain to obtain the correction amount of the speed correction command value of the main machine, and the feedback controller 46 multiplies the looper angle by the feedback gain and the correction amount of the speed correction command value of the main machine. Then, the feedback controller 47 multiplies the looper angle by the feedback gain to obtain the correction amount of the speed command value of the looper electric motor.

Blocks 21-24 and blocks in FIG.
When the process to be controlled shown in 26 is written as a state equation, the following equations (15) and (16) are obtained.

[0040]

(Equation 7) In the same manner as described above, vector display of state quantity x = [t _f θ] ^T vector display of control quantity y = [t _f θ] ^T vector display of operation quantity u = [ΔV _RREF ω _REF ]
^{When the} state equation is expressed as ^T , the following equation (17) is obtained.

[0041]

(Equation 8) Here, the dimensions of each matrix are 2 × 2 for A _{A and} 2 × 2 for B _A.
2, C _A is 2 × 2, and these are shown in the following formula (18).

[0042]

[Equation 9] Further, in order to control both the looper angle and the rolled material tension in the looper angle control system, the above equation (16) is modified as follows.

[0043]

(Equation 10) Here, the looper angle θ which is one of the control amounts in the equation (16) is changed to y ₂ in the equation (20) by the equation (19). y ₂ = C ₁ t _f + θ (20) The meaning of the weighting parameter C _{1 in} the equation (20) and the setting method thereof are as described in the first embodiment.

By using the model of the process to be controlled using the above equations (15) and (19), the rolled material tension t
The control gains of the blocks 41 to 47 can be expressed by the following equations on the assumption that _f and the looper angle y ₂ are made non-interfering. Block 41: K _IO 11 = -ω _TC (C ₁ · E · g _L · F ₂ ) / {E (1 + f)} (21) Block 42: K _IO 12 = ω _HC · g _L · F ₂ / (1 + f) ) (22) Block 43: K _IO 21 = -C ₁ · ω _TC · g _L (23) Block 44: K _IO 22 = g _L · ω _HC (24) Block 45: K _FO 11 = -L / {E (1 + f)} (25) Block 46: K _FO 12 = g _L · F ₂ / (1 + f) (26) Block 47: K _FO 22 = g _L (27) Where, ω _TC : Designated response of tension control system Cut-off frequency (rad / s) ω _HC : cut-off frequency (rad / s) of the specified response of y _{2 in} the equation (20), and each specifies a desired value. Note that K _FO 21 was 0 and was omitted.

The control gains of the above equations (21) to (27) are composed of mathematical expressions of the variables of the target process model and the variables of the designated response. Variables E, F ₂ , L, g _L ,
f is a variable expressing the model of the controlled process,
ω _TC and ω _HC are variables for designating the response of the tension and the looper angle, and C ₁ is a weight parameter for multiplying the rolled material tension added to the looper angle as a control amount for the looper angle control. σ ₁ and σ ₂ are set in the control calculation means 12 from the setting means 14 as variables for adjusting the response between the stand tension and the looper height, respectively. The control calculation means 12 substitutes these set values into the equations (21) to (27) to calculate the control gains of the blocks 41 to 47, and calculates them as numerical values together with the set values σ ₁ and σ ₂ .

Thus, also in the second embodiment, as in the first embodiment, there is no need to numerically solve the Riccati equation or use a control gain table, and the main machine and the looper motor are Since the rolled material tension is controlled in cooperation with each other, the rolled material tension and the looper height can be optimally controlled.

The "looper multi-variable control device" filed by the same applicant as the present application and disclosed as Japanese Patent Laid-Open No. 5-337529 is the above-mentioned equation (2), (3).
A, B, and C in the formula and the formula (6) are 5 × 5 and 5, respectively.
The matrix is a 5 × 2, 2 × 5 matrix, and differs from the present invention in that feedback of the main engine speed is required.

[0048]

As is apparent from the above description,
According to the present invention, when controlling the looper and the tension in the hot rolling, the controller gain is expressed by using the process variable and the variable indicating the designated response, so that it is optimal for the state of the rolled material and the operating condition. It is possible to control the looper and the tension, which contributes to stable operation. Further, according to the present invention, since it is not necessary to have the numerical value table required in the conventional method, the labor required for maintaining and managing the table can be reduced. Furthermore, by using the looper angle also for controlling the rolled material tension, it is possible to achieve better rolled material tension control performance than the method in which the rolled material tension and the looper height are made non-interfering, and stable operation is possible. Can contribute.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a first embodiment of a looper multivariable control device according to the present invention together with an applicable rolling mill.

FIG. 2 is a block diagram showing a detailed configuration of a control system of the embodiment shown in FIG.

FIG. 3 is a block diagram showing a detailed configuration of a control system of a second embodiment of a looper multivariable control device according to the present invention.

[Explanation of symbols]

 1 Rolled material 2 i-th stand rolling mill 3 i + 1-th stand rolling mill 4 Looper 5 Tension detection device 6 Looper angle detection device 7 Looper electric motor 8 Rotational speed detection device 9 Looper electric motor speed control device 10 i-th stand rolling main motor 11 Main machine speed Control device 12 Control calculation means 13 Model 14 Setting means

Claims (3)

[Claims] 1. A rolling material tension follows a target tension value by using a multi-variable system as an interfering system between a height of a looper arranged between stands of a tandem rolling mill and a rolling material tension between stands where the looper is arranged. In the looper multi-variable control device that makes the looper height follow the looper height target value, a multi-variable system of looper height and rolled material tension is modeled. A two-input two-output system in which the tension is multiplied by the weight parameter and added to the looper angle, and the manipulated variable is the rolling main motor speed correction command value and the looper motor speed command value. Of the tension, looper angle and looper motor speed, the model of the controlled process that includes at least the rolled material tension and looper angle, the target value of the rolled material tension, the target value of the looper height, and the above-mentioned control Variables that represent the model of the target process, variables that specify the response of rolled material tension and looper height, variables that adjust the response of rolled material tension and looper height, and settings that set the weight parameters, respectively. Means, and the set value set by the setting means is substituted into the control gain formula corresponding to the model of the controlled process, the control gain is obtained as a numerical value, and the speed correction of the rolling main motor is performed using this control gain. A control calculation means for calculating a command value and a speed command value of the looper electric motor; and adding the speed correction command value calculated by the control calculation means to the speed control system of the rolling main electric motor, and by the control calculation means. A looper multi-variable control device, wherein the calculated speed command value is added to a speed control system of the looper electric motor. 2. When the model of the process to be controlled uses the rolled material tension and the looper angle as internal state variables, the control calculation means multiplies the rolled material tension by a first feedback gain and the speed of the rolling main motor. It is used as the correction amount of the speed correction command value of the control system, and the looper angle is multiplied by the second feedback gain to be the correction amount of the speed correction command value of the speed control system of the rolling traction motor, and the looper angle is multiplied by the third feedback gain. The looper multivariable control device according to claim 1, wherein the looper motor speed control system has a speed command value as a correction amount. 3. When the model of the controlled object process uses rolling material tension, looper angle and looper motor speed as internal state variables, the control calculation means multiplies the rolling material tension by a first feedback gain and rolls. The correction amount of the speed correction command value of the speed control system of the main motor is used as the correction amount of the speed command value of the speed control system of the looper motor by multiplying the looper angle by the second feedback gain.
The looper multivariable control device according to claim 1, wherein the looper multivariable control device is configured to obtain a correction amount of a speed command value of a speed control system of the looper electric motor by multiplying the feedback gain by