JPH0635508A - Fuzzy controller - Google Patents

Abstract

PURPOSE:To provide a fuzzy controller which can fetch a phenomenon that continues for a long period. CONSTITUTION:An input processing part 1 compares various input signals received from a process controlled system with the set value and output the deviation of these signals. Then a correcting part 22 detects a case where certain condition lasts for a fixed period or longer for the input signals. A fuzzy controller consists of both parts 1 and 22 and a fuzzy control part which performs a fuzzy operation based on the deviation signal given from the part 1 and the 'IF-THEN rule' and outputs a control signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuzzy control device for performing a fuzzy operation on a deviation between an input signal given from a process control object and an internal set value and outputting a control signal to the process control object. , To improve its controllability.

[0002]

2. Description of the Related Art A fuzzy controller used in the field of process control generally receives input signals e ₁ and e ₂ (temperature signal, pressure signal, etc.) of various sensors, etc., which are subject to process control, and inputs fuzzy operation thereto. Control signal u to the actuator or the like installed in the process control target.
Is adopted. In particular, the control rule "IF THEN rule" is generally used as the fuzzy operation. That is, when the input signal e ₁ is negative and the input signal e ₂ is positive, the output control signal u is slightly increased (Δy) from the current value y.
IF THEN rule ")," IF e ₁ > 0, e ₂
<0 THEN u = y + Δy ”is used to obtain the control signal u. Then, assuming all cases, such a control rule is assembled and fuzzy control is constructed. The control device has the above-described control rules in a table form and can output the control signal most suitable for various input signals.

In the above fuzzy control device, for example, the difference Δ between the current input sample value PV _k and the previous input sample value PV _k−1 from the process control target.
PV _k = PV _k −PV _k−1 is adopted, or the second-order difference value Δ ² PV _k is also referred to by referring to the previous difference ΔPV _k−1.
= ΔPV _k −ΔPV _k−1 is generally used. Especially, when the control cycle is short, instantaneous data can be taken in to obtain an optimum control signal, so that extremely accurate control can be performed. It can be carried out.

[0004]

Generally, in such fuzzy control, when performing control over a relatively long period (several days), the input sample value of the current day and the input sample value of the previous day are compared. The control operation is executed so as to obtain the difference. However, in the case of a special process control target, there are some cases in which the above-mentioned control rule cannot be exercised unless an input signal that continues for a long period of hours or days is acquired. When dealing with a controlled object, it was necessary to specially create a program that matched the controlled object and install this program outside the control device to deal with it. As described above, the fuzzy control device that exercises the control rule every short time has a problem that it cannot take in the continuous phenomenon for a long time. An object of the present invention is to solve the above problems, and an object thereof is to realize a fuzzy control device that can match any control target.

[0005]

SUMMARY OF THE INVENTION The present invention which achieves such an object is provided with an input processing unit which receives various input signals from a process control target, compares them with a set value, and outputs a deviation thereof.
Based on the deviation signal given from the input processing unit, "IF
A fuzzy control device including a fuzzy control unit that performs a fuzzy operation according to a "THEN rule" and outputs a control signal, wherein a correction unit that detects a case in which a certain condition of the input signal continues for a certain period or more is provided. Is a fuzzy control device.

[0006]

The fuzzy control device of the present invention executes the operation related to the fuzzy control and outputs the control signal when the input signal input to the device continues for a certain period of time, that is, a certain condition continuously. obtain.

[0007]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a conceptual diagram of the configuration of a fuzzy control apparatus of the present invention. The inventive apparatus is composed of two large blocks, an input processing section 1 and a fuzzy operation processing section 2, and further a compensating section 3 for generating an output signal. Equipped with.

The input processing unit 1 receives an input sample value PV _n (k) from a process control target (not shown) and a set value signal S.
This block receives V _n (k) and performs the next calculation. still,
The integer n is the number of input signals given from the process control target. For example, in this embodiment, n = 16 (16 points).
It is assumed that 16 different signals can be input. The type of calculation is the previous input sample value PV for the current input sample value PV _n (k) of interest.
_n (k-1) difference ΔPV _n (k) with _{= PV n (k) -PV n} (k-1), 2 -order difference delta ² PV _n with the last differential ΔPV _n (k-1) ( k) ＝
ΔPV _n (k) -ΔPV _n (k-1), deviation DV _n (k) = PV _n (k)-
SV _n (k), deviation difference ΔDV _n (k) = DV _n (k) −DV _n (k-
1), the second-order difference Δ using the previous difference ΔV _n (k-1)
² DV _n (k) = ΔDV _n (k) −ΔDV _n (k-1) etc. are calculated. Actually, only the values used for the fuzzy control are calculated without performing all the above calculations.

The fuzzy operation processing unit 2 performs a fuzzy operation on an n-point (16-point) signal supplied from the input processing unit 1, and the input sample value PV.
_n (k) is always taken in, and it is judged whether or not this input sample value PV _n (k) satisfies certain conditions, and the correction unit 22 that holds this value, counts minutes, hours, days, periods, etc. This block is provided with a clock unit 23. Here, the above-mentioned constant condition is such a condition that the input sample value PV _n (k) is compared with the previous input sample value PV _n (k-1) and the difference is within a certain range. Therefore, the correction unit 22 always makes such a condition conformance determination of the input sample value. The clock unit 23 also has a timer-like function, and outputs an alarm output to the correction unit 22 when a certain period of time and a certain number of days are counted.

The compensating unit 3 has a function of receiving the correction signal from the correction unit 22, multiplying the correction signal by a gain G _m , and adding (or subtracting) the bias B _m , if necessary, and using a switch. The control signal MV _m (k) is output by overriding the correction signal by SW. Where m
Is the number of control signals to be given to the process control target, and can be output to, for example, 4 points (m = 1, 2, 3, 4). That is, this fuzzy control device can obtain input signals from up to 16 points of the process control object, perform fuzzy calculation, and give control signals to up to 4 points of the process control object. The compensator 3 may output the increment ΔMV _m (k) with respect to the control signal MV _m (k).

Next, FIG. 2 shows an example of control rules set in the apparatus of the present invention having such a configuration. A feature of the control rule set in the device of the present invention is that a condition that a certain fixed condition (conditions 1, 2 and 3 in the example of FIG. 2) continues for a long time is incorporated as a precondition. For example, in the control rule 1, the condition PV ₁ (process amount such as temperature and flow rate) exceeds the value 140 from 8th to 12th.
Based on the precondition that it is continuous for a day, control is performed to decrease the process control output MV ₁ by ΔMV ₁ = −0.1. And when programming, "
IF 8 <DD <12, PV ₁ > 140 THEN Δ
MV ₁ = -0.1 "(DD is the number of days) it describes as.
Rule 2 is similarly described with similar control. The rule 2 is 10 when the condition PV ₁ exceeds the value 140.
Based on the precondition that it is 12 consecutive days from the day, the control is to decrease the process control output MV ₁ by ΔMV ₁ = −0.2.
10 <DD <12, PV ₁ > 140 THEN ΔMV
₁ = -0.1 "(DD is the number of days). The same applies to the following process conditions PV ₂ , PV ₃ , PV ₃ ,
Depending on the number of days the PV _4, PV _5, PV ₆ is continuous, varying the increment .DELTA.MV ₁ control output MV _1.

The operation of the apparatus of the present invention shown in FIG. 1 constructed as above will be described. Normally, in the input processing unit 1, the deviation DV _n (k) = PV _n (k) −SV _n (k) of the input signal PV _n (k) from the preset setting value SV _n (k). )
And the fuzzy operation unit 2 in the fuzzy operation processing unit 2
Send to 1. The fuzzy calculation unit 21 performs a fuzzy control calculation according to the set control rule, and sends the control output to the compensation unit 3. On the other hand, the correction unit 22 incorporates the value PV _n (k) and the value DV _n (k) from the input processing unit 1 and incorporates the number-of-days information from the clock unit 23,
The management of the number of days, which is a part of the preconditions, is performed, and when the preconditions in the control rule as described above (the number of days defined and the predetermined conditions continue) are satisfied, a correction signal is sent to the compensating unit 3.
In the compensator 3, if necessary, the proportional gain G is added to the correction signal.
multiplied by _m, adds the bias B _m. Further, when the correction signal of the correction unit 22 is overridden by the control signal from the fuzzy calculation unit 21, the control signal is added via the switch means SW. In this way, the compensator 3 outputs the control signal MV.
_m (k) or its increment MV _m (k) is output.

As described above, it is possible to realize the fuzzy control of the process amount that normally handles instantaneous changes, and to continuously maintain the same state for many days, which has been supported by external software until now, and then fuzzy. Fuzzy control that outputs a signal can also be realized.

[0014]

As described above, according to the present invention,
In a single fuzzy controller, fuzzy control can be realized for both a short-term phenomenon and a long-term phenomenon.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of the configuration of a fuzzy control device embodying the present invention.

FIG. 2 is a diagram showing an example of a control rule set in the device of the present invention.

[Explanation of symbols]

 1 Input Processing Section 2 Fuzzy Calculation Processing Section 21 Fuzzy Calculation Section 22 Correction Section 23 Clock Section 3 Compensation Section

Claims (1)

[Claims] 1. An input processing unit which receives various input signals from a process control target, compares the input signals with a set value, and outputs a deviation thereof.
Based on the deviation signal given from the input processing unit, "IF
A fuzzy control device including a fuzzy control unit that performs a fuzzy operation according to a "THEN rule" and outputs a control signal, wherein a correction unit that detects a case in which a certain condition of the input signal continues for a certain period or more is provided. Fuzzy control device.