JPH038886A - Method for controlling profile of thickness - Google Patents

Abstract

PURPOSE:To decrease the unevenness of thickness of a sheet in a short time by controlling slice bolts using a fuzzy rule to operate the objective slice bolt and each two slice bolts at both sides of the objective bolt in respective specific directions. CONSTITUTION:The output of a process 10 is inputted to a deviation operating block 11 and the control signal to operate a slice bolt is calculated by applying a fuzzy rule to the control deviation and its variation with time. The control signal is applied to a slice bolt in the process 10. The opening of a slice lip at the position of the operating slice bolt and the openings of two adjacent bolts are operated in the same directions and the openings of the slice lip at the position of the slice bolt adjacent to the objective bolt but one in the opposite direction.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a control method for controlling the thickness profile of a sheet, and is particularly suitable for use in controlling the basis weight profile in the width direction of a paper machine. The present invention relates to a thickness profile control method.

<Prior art> Figure 10 shows an overview of a paper machine. In this figure, pulp, which is a raw material, is discharged into a wire bart 2 through a gap in a slicing lip 1 and made into a sheet, and the absolute dry basis weight profile of this sheeted paper is measured by an absolutely dry basis weight sensor 3.
Detected in The detected absolute dry basis weights x1 to XN are input to the control unit 4 to calculate control amounts u1 to uH, and the slice bolts 5 are controlled by the control amounts u1 to IJH to determine the gap profile of the slice lip 1. adjusted,
The amount of pulp discharged is controlled. In this way, the absolute dry basis weight profile of the paper is controlled to a predetermined value.

In such a control method, the following relationship exists between the control amount vector U output by the control section 4 and the bone dry basis weight vector X detected by the bone dry basis weight sensor 3.

w = A u+ A is an interference matrix, related to the transfer function of the control unit 4,
When the slice bolt 5 is moved, not only the opening degree of the slice lip directly below it but also the opening degree of the surrounding area changes, so the interference matrix A is not zero only for the diagonal elements and the elements around them, and also for the diagonal elements. becomes a symmetric banded diagonal matrix. 1st
Figure 1 (A) shows an example of a typical band diagonal matrix.

For such a process, a distribution coefficient matrix M is used to eliminate the interference of the slice bolt 5. That is, if the variation in the controlled amount is ΔU, and the difference from the target value of the absolute dry basis weight sensor 3 is ΔX, then Δu = Gc (s) MΔ
l Go: The distribution matrix M should ideally be the interference matrix A so that it becomes the transfer function of the control unit 4.
Use the inverse matrix of Fig. 11 (B) shows the distribution matrix M derived from the interference matrix shown as (A>), and Fig. 12 shows the interference pattern. If the difference in length) is negative, the position of the slice bolt 'I! a.

It becomes clear that the slice lips ``al'' and ``al'' on both sides of ``a'''' should be operated in opposite directions, and that ``a2'' on both sides of ``al'' should be operated in the same direction as ao.

In recent years, fuzzy control based on fuzzy theory has gradually come into use in process control. Since the basic principles of control are considered to remain the same in fuzzy control, it is thought that this can be achieved by converting the method described above into fuzzy rules.

<Problems to be solved by the invention> However, it has become clear that appropriate control cannot be achieved even if the concept of the conventional control method is converted into fuzzy rules as is. Figure 13 shows the simulation results when the conventional control method is made into rules as is, that is, when control is performed using the interference pattern shown in Figure 12.The horizontal axis is time, and the vertical axis is the standard for thickness variation. It is a deviation.

As is clear from this, it was found that the variation in thickness increased with the passage of time, making it impossible to properly control it.

<Object of the Invention> An object of the present invention is to provide a thickness profile control method that can appropriately control the thickness profile by fuzzy control.

Means for Solving the Problems> In order to solve the above problems, the present invention applies a fuzzy rule to the control deviation and its time change to obtain the operation amount of the slice bolt, and also determines the position of the slice bolt to be operated. The opening degree of the slice lip and the opening degrees of the slice lips on both sides thereof are operated in the same direction, and the opening degrees of the slice lips at the slice bolt positions on both sides thereof are operated in the opposite direction.

Effect> By optimizing the control direction of the opening degree of the slice lip, stable control can be executed in a short time.

<Embodiment> The present invention is a thickness profile control method using fuzzy control. FIG. 1 shows the configuration of an apparatus for implementing the thickness profile control method of the present invention. In FIG. 1, 10 is a process, which includes the paper machine described in FIG. 8. The output of this process, that is, the measured value of the absolute dry basis weight in the width direction of the paper, is input to the deviation calculation block 11,
The deviation from the separately input set value is calculated. 12 is a fuzzy controller group, one to one for the slice bolt
Multiple fuzzy controllers 121 to 12n compatible with
is included. The inference status of the fuzzy controller group 12 is displayed on the inference status display section 13, and the control parameter changing section 14 gives control parameters and calculates the operation amount for operating the slice bolt. This manipulated variable is applied to the slice bolt within the process 10. Second
The figure shows the correspondence between the deviation calculated by the open base calculation block 11 and the fuzzy controllers 121 to 12n.

The bone dry basis weight is detected at a plurality of positions corresponding to each slice bolt, and a deviation is calculated for each of the plurality of measured values. To each fuzzy controller of the fuzzy controller group 12, the deviation corresponding to the surrounding position considered by the position is also input simultaneously.6For example, the fuzzy controller 121 that calculates the operation amount of the slice bolt 1 has slice bolts i-2 to Five deviations corresponding to 1-t-2 are input. An appropriate value for the number of input deviations is selected depending on the interference width of the process.

Figure 3 (A>) shows an interference pattern to explain this control method. i-2 to i+2 are the positions of the slice bolts. (B) is the basis weight profile, and the arrow in (C) is the control deviation. is the direction in which the slice bolt is operated when The slice bolts on both sides of the target slice bolt are operated in the opposite direction.In other words, the opening degree of the slice lip at the position of the slice bolt of interest and the slice bolts on both sides of the target slice bolt changes in the same direction. The opening degree of the slice lip at the slice bolt position changes in the opposite direction.

Next, a fuzzy rule for performing this operation will be explained. The control rule for the control deviation e is as follows.

■If the control deviation e・ is negative Raise slice bolt 1-2 slightly.

■If the control deviation e is negative Lower slice bolt 1-1 slightly.

■If the control deviation e is negative Lower the slice bolt l.

■If the control deviation e・ is negative Slightly lower slice bolt i+1.

■If the control surface difference e+ is negative Slightly raise slice bolt i+2.

If this rule is rewritten as a rule for sliced bolt i, it will be as follows.

■If the control deviation e1-2 is negative, raise the slice bolt i a little.

■If control deviation ei-1 is negative, lower slice bolt 1 a little.

■If the control deviation e is negative Lower slice bolt i.

■If the control deviation e'+ is negative, lower slice bolt 1 a little.

■If the control surface difference ei+2 is negative, raise the slice bolt i a little.

However, the control deviation e, ~e, are each sly +-2
++2 There are values for Subolt i-2 to i+2. Since this rule is a static rule, a dynamic rule related to temporal changes in control deviation is added. That is, as shown in FIG. 4, the control deviation is classified based on whether the control deviation at time -1 is positive or negative, and it is further classified according to whether the control deviation increases or decreases from time -1 to time k. Now, assuming an input/output relationship in which increasing the slice bolt increases the control amount (thickness), the following dynamic rule is derived.

■If e is negative and Δe is negative, lower the slice bolt l.

■If e is negative and Δe is positive, lower the slice bolt l slightly.

■If e is positive and Δe is negative, raise slice bolt i a little.

■If e is positive and Δe is positive, raise the slice bolt i.

However, Δe is the difference between the control deviation e at time k and the control deviation at time −1. If we summarize the rules of 0 or more, we can derive the following 20 rules. 6 (1) If e
If is negative and Δe1-2 is negative, increase the slice bolt i by +-2.

(2) If e, is negative and Δei-2 is positive, -
2 Slightly raise the slice bolt l.

(3) If e, is positive and Δei-2 is negative, -
2 Lower the slice bolt i a little.

(4) If e, is positive and Δe1-2 is positive, +
-2 Lower slice bolt 1.

(5) If ei-1 is negative and Δei-1 is negative, lower the slice bolt i.

(6) If e, is negative and Δei-1 is positive, -
1 Lower the slice bolt i a little.

(7) If e・ is positive and Δei−1 is negative, −
1 Slightly raise slice bolt 1.

(8) If e, is positive and Δei-1 is positive, -
1 Raise slice bolt 1.

(9) If e・ is negative and Δe・ is negative, lower slice bolt 1.

(10) If e・ is negative and ΔJ is positive, lower slice bolt 1 a little.

(11) If e is positive and Δe・ is negative, raise the slice bolt l slightly.

(12) If e is positive and Δe is positive, then 1 Raise the slice bolt i.

(13) If e・ is negative and Δei+1 is negative, lower the slice bolt I by 1+1.

(14) If e, is negative and Δ”i+1 is positive, then 1+1 lower the slice bolt 1 a little.

(15) If e, is positive and Δe1+1 is negative, raise the 1+1 slice bolt i a little.

(16) If e is positive and Δei+1 is positive, increase the slice bolt i by 1+1.

(17) If e・ is negative and Δe1,2 is negative, increase the slice bolt i by 1+2.

(18) If e is negative and Δei+2 is positive, 1÷2 raise the slice bolt l a little.

(19) If ei+2 is positive or Δei+2 is negative, lower the slice bolt i a little.

(20) If ei+2 is positive and Δci+2 is positive, lower the slice bolt i.

When these rules are rewritten according to the fuzzy rules, the following rules are finally derived.

f e , iS posttrve andΔe
, is Po5itiv++2
++2e then Δu
, is NegatiVe bigf e -i
S Negative and Δe, is Po5i
tiv++2
1+2a then Δu = is Po5
itive+te, ts PO31tiVe
andΔe, is Ne0ativ++2
1+2e
then Δu, is Negativeif
e, is Negative andΔe,
iS Nl3(latiV1÷2
1+2e then Δu
, is PO31tiVe bi(]if e
-is Po5itive and Δe, is
Po5itiv++1
ule then Δu −is Po5it
ive bigrt e -is Negative
andΔe, is Po5itiv++j
++1e the
n Δu , is Ne0atie+f e ,
is Po5itive and Δe −is N
e0ativ+41
1+1e then Δu-is Po5
Itive f e ・is Neaative an
dΔe, is Ne0ativ++1
1+1e the
n Δu −is Negative bigf
e is Po5itive and Δe,
is Po5ative then A u -is
Po5itive bigif e, is Neg
active and Δe, is Po5it
ivethenΔu, is Negative
eif e ・is Po5itive and Δ
e, rs Ne0atiBethen Δu
-is Po5it,ivef e is N
egative and Δe, ts Neg
active then Δu His NegatiV
e biQif e, is Po5itiv
e and Δe, is Po5itiv+
-11-1 e then Δu ils Po5itive b
igif e = is Negative a
nd A e -is Po5itiv+-1+-1 e then Δu, is Negative
ef e -is Po5itive and Δe
, is NegatiVl-11-1 e then Δu, is Po5iti
vefe, is Negattve an
d Δe , is Ne0atie+−11-1 e then Δu , is Negative
bigif e, is Po5itive
and Δe, is Po5itiv+-2
1-2 o then Δu−, is Neqativebi
gif e, is Negative
and Δe ・is Po5itiv+ −
2+ −2 e then Δu ・is Po5it
ivef e-is Po5itiv6and
Δe −is Ne(lat!V+−2+−2 e than Δu , is NegatiVe
It is negative and
Δe, is Ne(]atiV+-2+-
2 e then Δu ・ is Po5itiv
e bigIn addition, raising the slice bolt l is Δu,
1sPo3itive big, slightly raising the slice bolt i is Δu, is Po5ative, slightly lowering the slice bolt is Δu, is Ne0ati
Lower slice holt 1 to e is A u -is N
I am replacing it with egatrve big. Further, Δu + is the amount of change in the opening degree of the slice lip.

Next, examples of other rules will be explained based on FIG. This rule states that the dynamic change in control deviation is zero and the control deviation ek at a point in time is large in the positive direction, small in the positive direction, zero,
Large in the negative direction, small in the negative direction (A), the control deviation eh at the time is zero and its dynamic change is large in the positive direction, small in the positive direction, zero, small in the negative direction, large in the negative direction This is a case where nine cases (B) are adopted as the antecedent part of the rule. The following 45 control rules are used at this time. (1) to (9) are related to positions 1+2, (
10) to (18) are related to position i+1, (19)
~(27) is related to position i, (28) ~(36)
is related to position i-1, and (37) to (45) are related to position i-2. In addition, the control deviation is eo, its dynamic change is Ae −, Po5itive srgal
The set representing l is PS, the set representing Po5itive big is Pa, the set representing negative small is NS, the set representing negative big is NB, the set representing zero is 20, and the correction value of the opening degree of the slice lip is ΔU. represent.

(1) If e, i! i 20 a "ld Δ
e-1sPB1+2
1÷2then Δu, 1sNB (2) if e, is 20and Ae, 1s
PS++2 +
+2then ΔuisNs f3) if e-is ZOand Δe, 1
sZO++2 +
+2then Δu-isZO (4) if els 20and AeisNS
1+2 1÷2the
n Au・1sPs (5) if e i+2 then (6) if e i+2 then (7) + f e + + 2 hen (8) i ' e i+ 2 hen (9) if ”i+2 then (10) if e , +1 then (tl) if ei+1 then (12) ' f e i+ 1 hen (13) i f e H+ 1 hen (14) if e H+ 1 hen s20and Δe:+2 ΔU ・ +s PB sPBand Δei+2 Au , 1sNB SPSand Δe+2 ΔU・+s NS sNsand Δei+2 ΔU・+s PS SNBand Δei+2 Δu−isPB is 20 and Δe−is1+1 ΔU・+s NB is 20 and Ae・IS÷1 Δu−isNs is 70 and Ae, isI+1 Au, 1s20s 10 and Ae , is1+1 ΔU ・is PS is 10 and Δe−is1+1 Δu' iS Pa (15) if e , is PB and Δeis
Z01+11÷1 then Au 11sNB (16) if e -is PS and Δe, 1
s201+1 1+jt
hen Δu, 1sNs (17)if e, is NS and A
e, is 701÷11+1 then Au, 1sPS f18) if e 1s NB and Δe,
isl.

1+1 1+1then
Δu-isPB 119) l f e + i S 20 andΔ
eisPBthen Au-isPB (20) if e, is 10 and Δe, 1
sPsthen Δu, 1sPS (21)if e, is 10 andΔe i
I S 10then Δu, 1sZO (22)if e, is 20 and A
e, is N5then Δu, 1sNs (23) if e His 20 and Δe +
i S N Bthen Au 1sNB (24) l f e + i S P B a n
dΔe + i S 7' 0then Au
1sPB (25) if e iS PS and A
e, 1sZO1 then Au, 1sPs (26)if e・is NS and
Ae, 1s20then Δu-isNs (27) if e, is NB and Δ
e-is20then Au・1SNB (28) if e i-1i SI Oan
dΔei−1)iSPBthen Au 1s
NB (29) if e is 70 and
Ae, 1sPS+-11-1 then Au, 1sNs (30)if e, is 70 and
Ae, 1s20+-1+-1 then Δu, 1s20 (31) if e, is '10 and A
e, 1sNs+-11-1 then Δu-iSPS (32) if e, is 20 and Ae,
1sNB-1+-1 then Δu-isPB (33) if e, is Pa and Δe,
1s20+-1 +-1th
en Δu-isNB (34) if e, is PS
and Δ e , 1s20+-11-1 then Au isNs (35)if e H-1 then (3G) ' f e 1-i hen (37) if e i-2 hen (38) if ei-2 then ( 39) + f e r -2 hen (' O) + f e + -2 hen (1)if e,.

then (42)! f ei-2 then (43) + f e i-2 hen (44) i f e + -2 hens NS and Δe-1sZO-1 Δu, 1sPS S NB and Ae-is 10-1 Δu, 1sPB S 10 and Δe= l5PB-2 Δu, 1sNB 1 S 70 and A e H-2i S P S
Δu, 1sNs number is 70 and A e -is 10-
2 Δu 1s20 is 20 and Δe-15M5+-2 Δu, 1sPs is 20 and Δe-1sNB+-2 Δu, 1sPB is PB and Δe-1sZO+-2 Δu-isNB s PS and Ae ・ 1s Z0-
2 ΔU ・+s 83 s NS and Ae, isi! 0
-2 Δu-isPS (45) l f e H-2i S N Ba
ndΔe−1s70−2 then Δu, 1sPB FIG. 6 shows an example of the membership function.

(A) is a function related to the control deviation e, (B) is a function related to the change Δe in the control ζ expansion difference, and (C) is the correction value Δu.
It is a function related to =. NB, 113.20, PS,
Omit the description.

Fig. 7 shows the control procedure. First, the control deviation of the position of each slice bolt and the time difference of the control deviation are calculated based on the measured value of basis weight. 6 Next, inference is made based on the fuzzy rules mentioned above. Execute it, calculate the change in slice lip, calculate the operation amount of each Swiss bolt from this, and output it. Further, the inference status of an arbitrary slice bolt is displayed on the inference status display section 13. Furthermore, the operator observes the inference situation and changes the control parameters as appropriate when necessary. This operation is repeated at an arbitrary period. FIG. 8 shows an example of the screen displayed on the inference status display section 13. This allows the operator to understand whether the inference is being performed correctly and to change the control parameters as necessary. I can do it.

FIG. 9 shows an example of the control results. The horizontal axis is time and the vertical axis is the standard deviation of thickness variation, which corresponds to FIG. 13. As can be seen from this figure, the variation in thickness becomes small in a short time, indicating that control is being performed properly.

Although this embodiment describes profile control of the absolute dry basis weight of paper, it can also be applied to profile control of the thickness of plastic films and iron plates.

<Effects of the Invention> As explained above in Maki based on the embodiments, in this invention, the opening degree of the slice lip at the slice bolt of interest and the positions on both sides thereof is controlled in the same direction, and A fuzzy rule was set to control the opening degree at the slice bolt position in the opposite direction.

Therefore, there is an effect that thickness variations are reduced in a short time and good control can be achieved.

[Brief explanation of drawings]

1 and 2 implement the thickness profile control method according to the invention! 3 is a characteristic curve diagram showing the interference pattern, FIGS. 4 and 5 are diagrams showing how the control deviation changes over time, and FIG. 6 is an example of the membership function. Fig. 7 is a flowchart showing the control procedure, Fig. 8 is a display example of the inference situation, Fig. 9 is a characteristic curve diagram showing the control results, Fig. 10 is a diagram showing an overview of the paper machine, Fig. 11
The figures are examples of interference matrices and distribution matrices, FIG. 12 is an example of interference patterns, and FIG. 13 is a characteristic curve diagram showing control results in a conventional control method. 10... Process, 11... Open radical operation block, 1
2... Fuzzy controller group, 13... Inference status display section, 14... Control parameter changing section. Fig. f Fig. Fig. Fig. -1 - One-shout closure Fig. 5 (A) (8) Shuen Fig. Fig. δ Fig. Fig. Fig. 5 → Gin close

Claims (1)

[Scope of Claim] A thickness profile control method applied to an apparatus for discharging raw material from a slicing lip to form a sheet by changing the profile of the gap by a plurality of slicing bolts, the method comprising: The amount of operation to be operated is determined by applying fuzzy rules to the control deviation, which is the difference between the measured thickness value and the set value, and its time change, and the slice lip at the position of the slice bolt to be operated and the positions on both sides thereof. A thickness profile control method characterized by controlling the opening degrees of the slice lips in the same direction, and further controlling the opening degrees of the slice lips at the slice bolt positions on both sides in the opposite direction.