JP2980409B2 - Operating end characteristic correction method and process control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of correcting characteristics of an operating terminal used in a process control system having an operating terminal for controlling various control objects, and a process control apparatus for executing the method . In particular, the present invention relates to a method and a process control device for correcting an operation end characteristic in which characteristic correction of an operation end is improved.

[0002]

2. Description of the Related Art Generally, the characteristics of an operating end of a valve or the like are as follows.
The composite characteristic of the operating end characteristic and the process characteristic is selected so as to be linear. However, since a product having an arbitrary operating end specific characteristic cannot be manufactured, the synthetic characteristic is inevitably nonlinear. Therefore, in such a control system, correction of an operation end characteristic is performed using an operation signal in order to linearize a synthesis characteristic, that is, a process gain.

FIG. 2 is a block diagram of a conventional flow control system employing such an operation end characteristic correction method. That is, the flow control system guides the detected flow rate PV detected by the flow rate detector 1 to the speed-shaped adjustment calculation unit 2 and executes a PI or PID calculation based on a deviation between the target flow rate SV and the detected flow rate PV. Then, the obtained adjustment signal △ MV ₁ is introduced into the multiplication unit 3. The multiplication unit 3, to the adjustment signal △ MV _1, previous operation output signal sent from the characteristic correction coefficient converter 4 M
After multiplying by the correction coefficient k converted based on V _n-1 to obtain a correction adjustment signal △ MV, the speed-position type signal converter 5
Lead to. Here, the signal conversion unit 5 outputs the previous operation output signal M
The current position type operation output signal MVn is obtained by adding the correction adjustment signal △ MV to V _n−1 , and the obtained current operation output signal M
In this method, the control valve 6 is operated using Vn.

[0004]

However, in the control system as described above, after the correction coefficient k is obtained using the previous operation output signal MVn _-1 , this correction coefficient k and the output of the adjustment operation unit 2 are obtained. since in a manner to multiply the door, or Hen' the magnitude of the velocity-type regulating signal on the way, or when the operation end characteristic curve has changed greatly within a section, the characteristic correction over the entire current adjustment signal proper And the accuracy of the characteristic correction is greatly deteriorated.

Hereinafter, the reason why the characteristic correction cannot be properly performed will be specifically described with reference to an operation end characteristic curve shown in FIG. Now, the operating end characteristic curve changes in each of the sections A, B, and C. For example, y = (1/2) x in section A, y = 2x in section B, and y = (1/2) x in section C. This indicates a change in the characteristic.

Therefore, the section A of the characteristic curve (y = (1 /
2)) The previous operation output signal MV at point (a)
If the time adjustment signal △ MV ₁ regulatory calculating unit 2 from _n-1 must be moved to a point B section (b),
Since in the prior art are corrected adjusted signal △ MV ₁ by using the correction coefficient k obtained from the characteristics of y = (1/2) x A-section, moved to MV _ng of point (c) shown in FIG. ,
The operation output signal MV _n to the target would be greatly different from, can not be performed properly characteristic correction.

[0007] The present invention focus on the operation terminal characteristics over the whole area of which has been made in view of the above circumstances, adjustment signal △ MV ₁
Operation ends characteristic correction side to implement a high characteristic correction accuracy Te Align
It is intended to provide a method and a process control device .

[0008]

According to a first aspect of the present invention, there is provided a speed-type adjustment calculating unit based on a deviation between a target value and a control amount from a control target. Or PI
Run the D regulation computation takes the operation output signal by performing characteristic correction on the obtained that adjustment signal by the operation, the operation ends characteristic correction method for a relationship between the operation output signal and the control amount linearly , along with obtaining this characteristic before correction operation signal by adding the current adjustment signal operation signal before correction that is obtained by inverse transformation from the previous operation output signal and Ru obtained from the velocity type regulation computing section This is an operation end characteristic correction method for obtaining a current operation output signal by performing a characteristic correction on the operation signal before the current characteristic correction. Claim 2
Is based on the deviation between the target value and the controlled variable from the controlled object.
Execute PI or PID adjustment calculation in speed type adjustment calculation unit
Then, characteristic adjustment is performed on the adjustment signal obtained by this calculation.
To extract the operation output signal for operating the operation end
Inverse conversion from the previous operation output signal
The characteristic correction inverse conversion means to extract the operation signal before correction
And the correction to an adjustment signal from the speed-type adjustment calculation unit.
Add the previous operation signal to obtain the current operation signal before the characteristic correction.
And the operation signal before the characteristic correction this time.
Characteristic correction conversion to obtain the current operation output signal by applying the characteristic correction
Means and the current operation obtained from this characteristic correction conversion means
From the output signal and the previous operation output signal, the current speed
Difference calculating means for extracting the adjustment signal;
Add the current speed type control signal to the previous operation output signal
To extract the position type operation output signal,
Signal type conversion means for operating the operating end using
A process control device characterized in that the process control device is characterized by:

[0009]

Therefore, according to the first aspect of the present invention , by taking the above means, after obtaining the operation signal before correction by inverting the previous operation output signal, the operation signal before correction is obtained. If the current adjustment signal is added to the operation signal before the current characteristic correction corresponding to the point (b) in the characteristic curve, the operation signal before the current characteristic correction is corrected. Can be matched to the operation end characteristics over the entire region, and proper characteristic correction can be executed. Also,
The invention of claim 2 is achieved by taking the above measures.
In addition to having the same operation as the first aspect of the present invention,
Performs characteristic correction on the speed type adjustment signal of the adjustment calculation unit,
Finally, the position type operation output signal is output by the position type signal conversion means.
To apply to the speed type controller with high convenience.
Control and safety can be secured.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method and the process control apparatus according to the present invention will be described below with reference to FIG. FIG.
In FIG. 2, the same parts as those in FIG. 2 showing the conventional control system are denoted by the same reference numerals, and detailed description thereof will be omitted. Hereinafter, an improved part (illustrated dotted frame) will be described.

That is, in this embodiment, in addition to the characteristic correction inverse conversion means 11 which takes in the previous operation output signal MV _{n -1} and obtains the operation signal MV _1n-1 before correction by inverse conversion, this inverse conversion means 11 operation signal MV before correction that is obtained by
_1n-1 to the adjustment signal {M} sent from the adjustment arithmetic unit 2.
Retrieve the operation signal MV _1n of Prior to this characteristic correction by adding the V ₁
And adding means 12 to issue Ri, operation signal before this characteristic correction M
A characteristic correction conversion means 13 to obtain the current corrected operating signal M _n performs characteristic correction conversion on the V _1n is provided.
Note that the inverse of the previous operation output signal MV _n-1
The reason for obtaining the operation signal MV _1n-1 before correction is
It is necessary to recognize the position of the operation output signal of
That's because. A linear equation with a simple characteristic curve of the operating end (valve)
(Line) is not necessary, but can be understood from the example shown in FIG.
In the case of characteristics that change depending on the position of the operation end,
If the position of the operation output signal of
The position of the PID adjustment signal to be corrected
You will not be able to know exactly what you are doing. That is, the operation output signal
Is located at the point (a) in FIG.
If it is possible, a complement corresponding to the next adjustment output signal △ MV ₁
Although the speed-type operation signal △ MV after the right is obtained, the point
If (a) cannot be grasped, the characteristics of section A
And output △ MVg,
Sex correction cannot be performed. Therefore, the previous operation output signal M
The operation signal MV _1n-1 before the correction is obtained by taking in the V _n-1 and performing inverse conversion.
Is what you get.

[0012] 14 is a differential operation circuit, which is a difference signal between the corrected operation signal Mn and the previous operation output signal MVn-1 of this obtained by characteristic correction conversion means 13, i.e. <br/> This time after obtaining a velocity form regulatory signals .DELTA.MV, the velocity type - it is to obtain a current position type operation output signal at position type signal converting means 15.

Therefore, according to the above-described embodiment,
If the previous operation output signal M
V_n-1Is inversely transformed to obtain the operation signal MV1n-1 before correction.
(Point (a) in FIG. 3), the operation signal MV before this correction
_1n-1To the adding means 12, where the uncorrected data shown in FIG.
Operation signal MV_1n-1(Point (a)) is the adjustment calculation section
2 This time adjustment signal @MV sent from₁Add
Thus, the adjustment signal MV before the current characteristic correction is performed._1n(FIG. 3
Points (c)). That is, MV_1n= MV_1n-1+ △ MV₁  The operation signal MV before the current characteristic correction by the calculation_1nGet
You.

Thereafter, the current operation signal MV before the characteristic correction is performed.
_1n the lead to characteristic correction conversion means 13, wherein the inherent characteristic correction, i.e. by performing the characteristic change amount of the characteristic correction in this adjustment signal △ MV within ₁ obtains the current correction operation signal M _n.
Then, after subtracting the operation output signal MVn _-1 after the previous characteristic correction from the current correction operation signal _Mn to obtain the adjustment signal △ MV after the current characteristic correction, the speed type-position type signal conversion means 5 in addition an adjustment signal △ MV after characteristic correction to the operation output signal MV _n-1 after the last characteristic correction give this position type operation output signal MV _n by using the position type operation output signal MV _n The control valve 6 is operated.

Therefore, according to the embodiment described above, FIG.
MV from point 3 (a)₁When there is a change
In the prior art, the variable coefficient of the section A (y = 1/2) is used.
The operation output signal MV_ngIs the point (c)
Become. That is, the operation output signal MV_ngIs MV_ng= MV_n-1+ △ MV_g  However, in the case of the method of the present invention, the inversely converted signal MV having the characteristic
_1n-1And @MV₁Correction conversion using the signal obtained by adding
MV_n= MV_n-1+ △ MV An operation output signal at point (b) is obtained, and an adjustment signal
Performs characteristic correction reliably even if there is a characteristic change within the range of
it can.

The present invention is not limited to the above embodiment. For example, by adding the speed type-position type signal conversion function to the adding unit 12, the difference calculation unit 14 and the speed type-position type signal conversion unit 5 are deleted from FIG.
A simple configuration such that n = MVn can be adopted ( claim 1). That is, the current correction operation signal Mn is
Operate the control valve 6 with the position type operation output signal MVn at the final stage
Is what you do. However, in this case, there are difficulties due to the bumplessness at the time of changing the characteristic curve, the consistency of the speed-position-type signal conversion unit 5 and the upper and lower limits of the final operation output signal MVn, and the like. May need. In addition, the present invention can be implemented with various modifications without departing from the scope of the invention.

[0017]

As described above, according to the present invention, it is possible to match the operating end characteristics over the entire adjustment range of the adjustment signal, and to perform highly accurate characteristic correction.
An operation end characteristic correction method can be provided. In addition , speed shape adjustment performance
Performs characteristic correction on the speed control signal of the
As a position type operation output signal by the position type signal conversion means
This makes it possible to apply the technology to
A process control device that can ensure the integrity can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an operation end characteristic correction method according to the present invention.
FIG.

FIG. 2 is a configuration diagram of a flow control system for explaining a conventional method .

[3] Conventional characteristic correction and shows a characteristic correction curve example compares explain the characteristics correction according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flow detector, 2 ... PI or PID adjustment calculation part, 5
... speed-position type signal converter, 6 ... control valve, 11 ... characteristic correction inverse conversion means, 12 ... addition means, 13 ... characteristic correction conversion means, 14 ... difference conversion means.

Claims (2)

(57) [Claims] 1. A running deviation PI or PID adjustment operation at a velocity type adjusting operation unit based on the control amount from the target value and the controlled object, subjected to a characteristic correction with respect to the adjustment signal that is obtained by the calculation taking out an operation output signal Te, the operation ends characteristic correction method for a relationship between the operation output signal and the control amount linearly, the speed and the operation signal before correction that is obtained by inverse transformation from the previous operation output signal with obtaining the operation signal before this characteristic correction by adding the current adjustment signal Ru obtained from the shape adjusting operation section, characteristic correction alms to this operation output to the current characteristic before correction operation signal A method for correcting operating end characteristics, comprising obtaining a signal. 2. A deviation between a target value and a control amount from a control target.
PI or PID adjustment performance in speed type adjustment calculation unit based on
Calculation, and adjust signal obtained by this operation
Performs characteristic correction and obtains operation output signals for operating the operation terminals.
Output from the process control device
Characteristic correction to extract the operation signal before correction by inverse conversion
Inverting means and an adjustment signal from the speed-type adjustment calculation unit
The operation signal before the correction is added to the current operation signal before the characteristic correction.
Addition means for obtaining the operation signal and the operation before this characteristic correction
The characteristic of obtaining the current operation output signal by performing characteristic correction on the signal
Correction conversion means, and the current value obtained from the characteristic correction conversion means.
From the previous operation output signal and the previous operation output signal
A difference calculating means for taking out the velocity type adjustment signal, the difference Starring
The current speed type adjustment signal of the
Signal in addition to the signal,
Position type signal converter that operates the operation terminal using the operation output signal
And a step .