JPH09184861A - Method and apparatus for detecting changing amount - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold a changing amount for a sampling period which is obtained by sampling measuring values related to a measuring object. SOLUTION: Signals to be measured are sequentially sampled by a sample hold circuit 10 for every sampling cycle and sampling values are stored. The deviation of the stored sampling value from a signal to be measured and input afterwards is integrated at an integrator 14. Immediately before an integration value of the integrator 14 is reset, the integration value of the integrator 14 is stored in a sample hold circuit, 18, and held during a next sampling cycle. The integration value is divided by a dividing circuit 20. A changing amount of the measuring value in the sampling cycle is detected by the dividing circuit 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a change amount detecting method and device, and more particularly, to a method in which the degree of change of a measured value obtained from a measurement target such as a process amount such as water level and water pressure or a state quantity of a plant is extremely gentle. Even in such a case, the present invention relates to a change amount detection method and apparatus suitable for accurately detecting the change amount.

[0002]

2. Description of the Related Art As a method of detecting the amount of change in a measurement value obtained by measuring a measurement target such as a process amount, for example,
The one described in JP-A-60-24428 is known. In this method, the measured quantity is sampled and detected at predetermined time intervals, the detected value is stored, and the stored value is compared with the measured quantity thereafter, and the difference between the two within the sampling cycle is integrated during the sampling cycle. Then
The amount of change in the measured amount is detected based on the magnitude of the integrated value. According to this method, it is possible to intermittently detect the amount of change in the measured value (measured amount) during the sampling period for each sampling period.

[0003]

However, in the conventional detection method, the amount of change in the measurement value obtained by measuring the measurement target is an intermittent value detected at each sampling cycle. However, even if is used, it is not possible to accurately control a controlled object controlled by an analog amount. That is,
In a control system that controls a controlled object according to continuous changes in the analog amount, even if the amount of change that is detected intermittently is used, the controlled object can be controlled only when synchronized with the sampling timing. Absent.

Further, in the conventional detection method, since the sampling period (integration period) is fixed, even if the amount of change in the measured value during the sampling period is small, if the accumulated change amount is insufficient, the resolution will be insufficient, Further, when the amount of change in the measured value is large, the amount of change is limited within a range that does not exceed the required capacity of the integrator, so that it becomes impossible to detect the measured value with high accuracy.

It is an object of the present invention to provide a change amount detecting method and apparatus capable of holding a change amount of a measured value obtained from a measurement object for at least a sampling period.

[0006]

In order to achieve the above-mentioned object, the present invention sequentially samples a signal under measurement indicating a measurement value of a measurement object every predetermined period, and obtains a sampling value obtained by this sampling. Sequentially store this value, compare the stored value with the signal under test that is input after that, integrate the deviation between the two within the sampling period, store this integrated value for the next sampling period, and A change amount detecting method for detecting the change amount of the measured value during the sampling period may be adopted.

When the change amount detection method is adopted, the integrated value is stored for the next sampling period, the stored integrated value is divided by the sampling period, and the change amount of the measured value between the sampling periods is detected from the divided value. You can also do it.

Furthermore, after the integrated value is stored for the next sampling period, the stored integrated value is divided by the sampling period, the divided value is divided by the sampling period, and the unit of the measured value from the divided value to the sampling period. It is also possible to detect the amount of change per unit time.

The sampling cycle can be set to any cycle.

According to the present invention, a sampling means for inputting a measured signal indicating a measured value of a measuring object and sequentially sampling the inputted measured signal at predetermined intervals, and a sampling value obtained by sampling of the sampling means are sequentially sampled. Sampling value storage means to be stored, an integrated value for sequentially comparing the stored value of the sampling value storage means and the measured signal input after the measured signal corresponding to this stored value, and integrating the deviation between the two within a sampling period. Means, integrated value storage means for storing the integrated value of the integrating means for the next sampling cycle, and change amount detection means for detecting the amount of change in the measured value during the sampling cycle from the integrated value stored in the integrated value storage means. This is a configuration of a change amount detection device including the.

When constructing the variation detecting device, the following components may be added to the components of the variation detecting device.

(1) A division means for dividing the integrated value stored in the integrated value storage means by the sampling cycle, and a change amount detecting means for calculating the change amount of the measured value from the division value of the division means during the sampling cycle. ing.

(2) Division means for dividing the integral value stored in the integral value storage means by the sampling period, and auxiliary division means for dividing the division value of the division means by the sampling period,
And a change amount detecting means for detecting a change amount of the measured value per unit time during the sampling period from the divided value of the auxiliary divided value.

(3) Sampling cycle setting means for setting the sampling cycle to an arbitrary cycle is provided.

According to the above-mentioned means, the sampling values obtained by sampling the signal under measurement are sequentially stored, and the stored value is compared with the signal under measurement input thereafter, and both are stored in the sampling cycle. Deviation is integrated, the integrated value is stored for the next sampling period, and the amount of change in the measured value between the sampling periods is detected from the stored integrated value. , Without synchronizing to the sampling period,
It can be used for a control signal of an analog control system. Further, by adjusting the sampling cycle to an optimum sampling cycle in accordance with the response of the controlled object, for example, the response of the application process, it is possible to detect the accurate change amount.
Furthermore, after dividing the integrated value by the sampling period, by dividing this divided value by the sampling period, the change amount of the measured value per unit time between the sampling periods,
That is, the rate of change can be detected. This rate of change indicates the slope of the function when the signal under measurement is expressed by a linear function, and therefore a predicted value that is predicted to change the signal under measurement can be obtained from this rate of change.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a change amount detecting device showing an embodiment of the present invention.

In FIG. 1, the change amount detecting device includes a sample hold circuit 10, a subtraction circuit 12, an integrator 14, an amplifier 16, a sample hold circuit 18, a division circuit 20, an amplifier 22, a division circuit 24, and a timing pulse generation circuit 26.
The sample-hold circuit 10 is connected to the input terminal 28, and the divider circuit 24 is connected to the output terminal 30.
It is connected to the.

A measured value obtained by measuring an object to be measured, for example, a measured signal relating to the water level, water pressure, temperature, pressure, voltage, current or the like of a thermal power plant is input to the input terminal 28. ing. The sample-hold circuit 10 receives the signal under measurement input to the input terminal 28 and the timing pulse 100 output from the timing pulse generation circuit 26, and as shown in FIGS. In response to, the signal under measurement is sampled at every predetermined sampling period, the sampling value (analog value) obtained by sampling is stored in the analog memory for the sampling period, and the stored sampling value is output to the subtraction circuit 12. It is supposed to do. That is, the sample hold circuit 10 constitutes a sampling means and a sampling value storage means.

The subtraction circuit 12 includes an inverter 32 and a resistor 3
4 and 36, the output of the sample hold circuit 10 is inverted by the inverter 32, the inverted signal is output to the integrator 14 via the resistor 34, and the signal under measurement from the input terminal 28 is output. The output is provided to the integrator 14 via the resistor 36. That is, the subtraction circuit 12 constitutes a deviation calculation means for calculating the deviation between the sampling value stored in the sample hold circuit 10 and the signal under measurement input to the input terminal 28 thereafter. The integrator 14 is an analog switch 38, a resistor 4
0, a capacitor 42, and an operational amplifier 44. The capacitor 42 is connected between the input and output of the operational amplifier 44, and the analog switch 38 and the resistor 40 are connected in parallel to the capacitor 42. The timing pulse generating circuit 2 is connected to the analog switch 38.
The timing pulse 102 is input from 6. As shown in FIGS. 2 (a) and 2 (e), the integrator 14 operates when the analog switch 38 is off, and the subtraction circuit 12
Is integrated, and the integrated signal is output to the sample hold circuit 18 via the operational amplifier 16. The integrated value integrated by the integrator 14 is
Analog switch 38 by timing pulse 102
It is supposed to be reset when is turned on. That is, the integrator 14 and the subtraction circuit 12 are configured as an integration unit that sequentially compares the sampled value stored in the sample hold circuit 10 and the signal under measurement input thereafter and integrates the deviation between the two within the sampling period. Has been done. The signal related to the integrated value obtained by the integrator 14 is amplified by the operational amplifier 16 by a proportional multiple and adjusted within the output range, and then the sample-hold circuit 1 is operated.
8 is input.

The sample and hold circuit 18 is shown in FIG.
As shown in (b) and (c), in response to the timing pulse 104 from the timing pulse generation circuit 26, a signal immediately before the integrator 14 is reset among the output signals of the operational amplifier 16 is sampled and It is configured as an integral value storage means for storing the sampling value in the analog memory during the next sampling period. For example, when the integrated value in the sampling cycle Δt0 is S1, the integrated value S1 is stored in the sample hold circuit 18 during the sampling cycle Δt1. Then, the integrated value stored in the sample hold circuit 18 is input to the division circuit 20 by a voltage signal.

The division circuit 20 is provided with a variable resistor 46 and a fixed resistor 48, the variable resistor 46 and the fixed resistor 48 are connected in series with each other, and the variable resistor 46 and the fixed resistor 48 make it possible. It is configured as a dividing unit that divides the output voltage of the sample hold circuit 18 and outputs the divided signal to the dividing circuit 24 via the amplifier 22. The variable resistor 46 is adapted to interlock with the variable resistor 50 of the timing pulse generating circuit 26, and when the resistance value of the variable resistor 46 is adjusted to a larger value (when the arrow moves downward). ), The sampling cycle is set to be large, and conversely, the sampling cycle is set to be small when the resistance value is adjusted to a small value. Then, by dividing the output of the sample hold circuit 18 by the divider circuit 20, the amount of change in the measured value during the sampling period can be obtained.

For example, as shown in FIG. 3, when the signal under measurement is represented by the function y = axt, the integral value S of the integrator 14 has a triangular area whose base is the sampling period Δt and whose variation ε is the height. Will be equivalent to. Therefore, the change amount ε is expressed by the following equation (1).

Change amount ε = 2 × S / Δt Here, ε = change amount S = integral value by the integrator 14 Δt = sampling period.

Next, the rate of change a can be calculated as shown in the following equation by further dividing the change amount ε by the sampling cycle by the division circuit 24.

Change rate a = ε / Δt = 2 × S / (Δt squared) The division circuit 24 includes a variable resistor 52 and a fixed resistor 54. The variable resistor 52 and the fixed resistor 54 are connected to each other. Are connected in series with each other. The division circuit 24 is configured as an auxiliary division unit that divides the output voltage of the amplifier 22 by the variable resistor 52 and the fixed resistor 54 and outputs the voltage obtained by the division as a signal indicating the change rate a. There is.

The output of the division circuit 24 indicates the amount of change in the measured value per unit time during the sampling period by dividing the amount of change ε by the sampling period Δt. Since the rate of change a corresponds to the slope of the function y shown in FIG. 3, it is possible to predict the changing value of the signal under measurement y from this value. Since the amplifier 22 having a gain of 1 is inserted between the division circuits 20 and 24, the mutual influence of the division circuits 20 and 24 is amplified (gain = 1).
Can be removed by 22. Also, the division circuit 24
Similarly to the variable resistor 46, the variable resistor 52 of FIG.
The sampling cycle of the division circuit 24 is arbitrarily set according to the resistance value of the variable resistor 50.

The timing pulse generating circuit 26 is constituted by a circuit element as shown in FIG. 4, for example, as a sampling period setting means.

The timing pulse generating circuit 26 includes a resistor R
1 to R10, capacitors C1 to C5, Zener diodes Z1 and Z2, diodes D1, amplifiers 56 and 58, a NOT gate circuit 60, NAND gate circuits 62 and 64, a NOT gate circuit 66, and NAND gate circuits 68 to 76. From the amplifier 58, as shown in FIG.
5, a triangular wave signal is output, and the amplifier 56 outputs a square wave signal, as shown in FIG. 5B. Further, from the diode D1, the signal shown in FIG.
The signal shown in FIG.
From the NAND gate circuit 62 shown in FIG.
From the NAND gate circuit 64 shown in FIG.
The timing pulse 104 shown in (g), the signal shown in FIG. 5 (h) from the resistor R10, the signal shown in FIG. 5 (i) from the NAND gate circuit 68, and the signal shown in FIG. 5 (j) from the NAND gate circuit 72. The timing pulse 100 shown in FIG. 5 and the timing pulse 102 shown in FIG. 5J are output from the NAND gate circuit 76, respectively. The pulse width of the timing pulses 100 to 104, that is, the sampling cycle is set arbitrarily by the resistance value of the variable resistor 50.

In the above structure, as shown in FIG. 2, when the signal under measurement is input to the input terminal 28, the sample and hold circuit 10 samples the signal under measurement at time t0 and holds the sampling value. , The sampling value is stored as 0 in this case. The stored sampling value is input to the integrator 14 via the subtraction circuit 12. Then, during the sampling period Δt0, the integrator 14 sequentially integrates the deviation between the stored sampling value and the signal under measurement input thereafter.
The integrated value S1 obtained by the integrator 14 is reset in synchronization with the timing pulse 102 at time t1, but the integrated value S1 immediately before resetting is the timing pulse 10.
The data is stored in the sample hold circuit 18 in synchronization with the signal No.
The integrated value S1 stored in the sample hold circuit 18 is held for the sampling period Δt1 and is divided by the dividing circuit 20 by the sampling period according to the equation (1). The divided value (ε1 = 2 × S1 / Δt1) is held for the sampling period Δt1 as the amount of change ε1 of the measured value in the sampling period Δt0.

Next, when the signal under measurement is sampled at time t1, the sampling value e1 is stored, and the deviation between the sampling value e1 and the signal under measurement is measured during the sampling period Δt1 (the value of the signal under measurement is e1). (While changing to ~ e2), they are sequentially integrated. Then, the integrated value S immediately before time t2
2 is stored in the sample hold circuit 18, and the stored integrated value S2 is sampled by the division circuit 20 in the sampling cycle Δ.
It is divided by t1 and this divided value (ε2 = 2 × S2 / Δt
2) is held as the amount of change ε2 of the measured value in the sampling period Δt1 during the sampling period Δt2.

As described above, in this embodiment, the instantaneous values (sampling values: e0, e1, e2,
..) deviation (e1-e0, e2-e1) is not used as the amount of change, but the deviation between the sampling value of the signal under measurement and the signal under measurement obtained thereafter is integrated for each sampling cycle. Since the change amount is detected based on the integrated value, the change amount of the measured value can be detected with high accuracy without being affected by noise even if the change of the signal under measurement is gradual. In addition, for each sampling cycle, the deviation between the sampled value of the signal under measurement and the signal under measurement obtained after that is integrated, the integrated value is divided by the sampling cycle, and this divided value is retained for the next sampling cycle. Therefore, even when the change amounts ε1, ε2, ... Are used as control signals of the analog control system, the change amounts can be used at arbitrary timings without synchronizing with the sampling cycle.

Further, in this embodiment, the change amount ε1,
Since .epsilon.2, ... Is further divided by the sampling period to obtain the change rate, the value of the signal under measurement can be predicted from this change rate.

Further, in this embodiment, the sampling period is arbitrarily set by the variable resistors 46, 50 and 52, so that the arbitrary sampling period can be set according to the response of the controlled object. For example,
Even if the signal under measurement is a signal relating to voltage, current, temperature, etc., the sampling cycle can be arbitrarily set according to the response of the signal under measurement.

Further, in the present embodiment, when the full scale of the change of the signal under measurement (hereinafter referred to as FS) is used, the detectable range between sampling cycles is ± 1%.
F. It is set as the change of S. The magnitude of the output signal of the change amount detecting device is + 1% F.S. When the change amount of S is 100%, the output becomes 100%, and -1% F.S. When the amount of change in S is 0%, the output is 0%, and the output of the amount of change during that time exhibits linear characteristics. Specifically, regarding the output of the change amount detection device, the detectable range is ± 1 during the sampling period.
% F. It is the same as the change in S, but 1% F.S. When the output changed to S / 6s, the output was 100%, and the output was 0% at -1% / 6s. Good results were obtained.

In the above embodiment, the division circuits 20, 2
4 is configured by using a variable resistor and a fixed resistor to divide the input signal. However, when the divided voltage signal from the resistor affects the amount of change or the rate of change, The accuracy can be further improved by obtaining the change amount and change rate of the digital amount of the output using the A / D converter and the digital processing device.

[0037]

As described above, according to the present invention,
The measured signal is sampled at each sampling cycle and the sampling value is stored.The sampled value and the measured signal input after that are compared to integrate the deviation between the two within the sampling cycle. Since the stored integral value is stored for each sampling period and the stored integrated value is divided by the sampling period, and the amount of change in the measured value between the sampling periods is detected from this divided value, the detected amount of change can be analogized at any timing. It can be used for a control signal of a control system such as a control system. Further, since the sampling cycle is set to an arbitrary cycle, the sampling cycle can be set according to the magnitude of the response delay of the measurement target, and the versatility can be improved.

Furthermore, the amount of change in the measured value per unit time during the sampling period can be held during the sampling period, and the amount of change per unit time can be used as the change rate to determine the future value of the signal under measurement. Can be predicted.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a change amount detection device showing an embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of each part of the apparatus shown in FIG.

FIG. 3 is a characteristic diagram for explaining a method of calculating a change rate by a divider circuit.

FIG. 4 is a circuit configuration diagram of a timing pulse generation circuit.

5 is a waveform diagram for explaining the operation of the timing pulse generation circuit shown in FIG.

[Explanation of symbols]

 10 sample and hold circuit 12 subtraction circuit 14 integrator 18 sample and hold circuit 20, 24 division circuit 26 timing pulse generation circuit

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shunji Mori 1-15-25 Higashi-Kanazawa-cho, Hitachi City, Ibaraki Prefecture Hitachi Electric Systems Co., Ltd. (72) Inventor Yuji Yamazawa 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Ltd., Hitachi, Ltd. (72) Koji Ono, Koji Ono, 500, Mt. Sanyu, Uchihara-cho, Higashi-Ibaraki-gun, Ibaraki Prefecture, Hitachi, Ltd., Hitachi Naka Electronics Co., Ltd. (72) Takanori Ito, Ibaraki-gun, Ibaraki Prefecture 500 Mt. Haramachi Sanyu Translated Mountain Inside Hitachi Naka Electronics Co., Ltd.

Claims (8)

[Claims] 1. A measured signal indicating a measured value of an object to be measured is sequentially sampled at predetermined intervals, sampling values obtained by the sampling are sequentially stored, and the stored value and the measured signal input thereafter are stored. A change amount detection method in which the deviations of the two in the sampling cycle are integrated by sequentially comparing and, the integrated value is stored for the next sampling cycle, and the amount of change in the measured value between the sampling cycles is detected from the stored integrated value. . 2. A measured signal indicating a measured value of a measuring object is sequentially sampled at predetermined intervals, the sampling values obtained by the sampling are sequentially stored, and the stored value and the measured signal input thereafter are stored. And are sequentially compared to integrate the deviation between the two within the sampling cycle, the integrated value is stored for the next sampling cycle, the stored integrated value is divided by the sampling cycle, and the measured value during the sampling cycle is calculated from the divided value. Amount detection method for detecting the amount of change in the. 3. A measured signal indicating a measured value of a measuring object is sequentially sampled at predetermined intervals, the sampling values obtained by this sampling are sequentially stored, and the stored value and the measured signal input thereafter are stored. And are sequentially compared to integrate both deviations within the sampling cycle, the integrated value is stored for the next sampling cycle, the stored integrated value is divided by the sampling cycle, and the divided value is divided by the sampling cycle. A change amount detecting method for detecting the change amount of the measured value per unit time during the sampling period from the divided value. 4. The variation detecting method according to claim 1, 2 or 3, wherein the sampling period is set to an arbitrary period. 5. Sampling means for inputting a signal under measurement indicating a measurement value of a measurement object and sequentially sampling the input signal under measurement, and sampling values obtained by sampling by the sampling means are sequentially stored. Sampling value storage means, and integration means for sequentially comparing the stored value of the sampling value storage means and the measured signal input after the measured signal corresponding to this stored value, and integrating the deviation between the two within a sampling period. An integration value storage means for storing the integration value of the integration means for the next sampling period, and a change amount detection means for detecting the change amount of the measured value during the sampling period from the integration value stored in the integration value storage means. Change detecting device. 6. Sampling means for inputting a measured signal indicating a measured value of a measuring object and sequentially sampling the input measured signal at predetermined intervals, and sequentially storing sampling values obtained by sampling of the sampling means. Sampling value storage means, and integration means for sequentially comparing the stored value of the sampling value storage means and the measured signal input after the measured signal corresponding to this stored value, and integrating the deviation between the two within a sampling period. , An integrated value storage means for storing the integrated value of the integrating means for the next sampling period, a division means for dividing the integrated value stored in the integrated value storage means by the sampling cycle, and a division value from the division value of the dividing means between the sampling cycles. A change amount detecting device comprising a change amount detecting means for detecting a change amount of a measured value. 7. Sampling means for inputting a measured signal indicating a measured value of a measuring object and sequentially sampling the input measured signal at predetermined intervals, and sequentially storing sampling values obtained by sampling of the sampling means. Sampling value storage means, and integration means for sequentially comparing the stored value of the sampling value storage means and the measured signal input after the measured signal corresponding to this stored value, and integrating the deviation between the two within a sampling period. , An integral value storing means for storing the integrated value of the integrating means for the next sampling period, a dividing means for dividing the integrated value stored in the integral value storing means by the sampling period, and a divided value of the dividing means for dividing by the sampling period. Auxiliary division means to be used and the measured value per unit time from the division value of the auxiliary division means to the sampling period. A change amount detecting device comprising a change amount detecting means for detecting a change amount. 8. A sampling cycle setting means for setting a sampling cycle to an arbitrary cycle.
Alternatively, the change amount detecting device described in 7.