JP3318649B2 - Measurement data processing apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measurement data processing device and method, and more particularly, to a control device such as a temperature controller or a temperature indicator, for example, a temperature input for outputting a converted temperature corresponding to a measurement voltage input from a temperature sensor. The present invention relates to a measurement data processing device as a unit and an improvement of a measurement data processing method used therein.

[0002]

2. Description of the Related Art Conventionally, as a measurement data processing apparatus of this type, for example, a measurement voltage E at equal voltage intervals from a thermocouple is used.
(N), E (n + 1), E (n + 2)... Corresponding to the temperatures T (n), T (n + 1), T (n + 2). ) Means the measurement voltages E (n), E (n + 1), E (n + 2) before and after ...
, A so-called linear approximation method is used. Symbol n is the number of measurement points in the measurement range of the thermocouple.

That is, as shown in FIG. 6, when a change in temperature (vertical axis) with respect to a measured voltage (horizontal axis) of a K-type thermocouple changes as a curve (solid line), the measured voltages E (n) and E (n)
Temperature T for any measured voltage E (i) during (n + 1)
(I) ′ is approximately calculated by the following equation (1) from a straight line approximating a curve like a one-dot chain line. T (i) ′ = [T (n + 1) −T (n)] / [E (n + 1) −E (n)] × [E (i) −E (n)] + T (n) (1)

In this linear approximation method, the same measurement voltages as the previously stored measurement voltages E (n), E (n + 1) and E (n + 2) can be measured accurately, but the measurement voltages E (n) and E (n)
The temperature corresponding to an arbitrary measurement voltage around (n + 1) and E (n + 2) is measured although an error [T (i) ′ − T (i)] occurs between the calculated approximate temperature and the true temperature. It is considered that the error decreases as the voltage interval decreases. That is, if a large number of relationship data between the measured voltage and the temperature are stored, the error can be reduced to a level that does not cause any problem.

[0005]

However, the measurement data processing device using the linear approximation method has the following problems. In other words, in recent control devices, many types of thermocouples and resistance temperature detectors are configured to be exchangeable and connectable, and even if the user exchanges and connects these temperature sensors, there is a tendency to respond. Since each temperature sensor has different measurement voltage and temperature relation data, the measurement voltage and temperature relation data for each temperature sensor is stored in advance, and one-touch switching operation is performed by the installed software etc. according to the exchange connection of the temperature sensor. It was configured to be possible.

However, in such a measurement data processing apparatus, when a large number of related data for each temperature sensor is stored, an enormous amount of storage capacity is required. In practice, for example, a K-type thermocouple is used as an example. In this case, 1500 μV (approximately 40
℃) The temperature data is stored at relatively coarse intervals
It was necessary to limit the number of stored relation data between the measured voltage and the temperature. Therefore, the measurement voltages E (n), E
(N + 1), E (n + 2) ...
Any other measurement voltage E (i) has a disadvantage that a non-negligible error easily occurs between the converted temperature T (i) ′ and the true temperature T (i).

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional drawback, and is intended to provide a high-precision method capable of minimizing a measurement value error corresponding to an arbitrary measurement voltage without increasing the number of measurement voltages to be measured in advance. It is an object of the present invention to provide a measurement data processing device and method.

[0008]

In order to solve such a problem, a measurement data processing apparatus according to the present invention comprises a measuring means for measuring a voltage of a measured value which changes in a curve according to a change of a control amount. A data storage means for storing in advance the corresponding data of the measured voltage at each interval and the corresponding value corresponding thereto; a section between adjacent measured voltages at equal intervals as one section, and an arbitrary measured voltage from the measuring means as an interval; When the measured voltages at both ends of the section including the section and the section continuous to the section are connected by a straight line on the curve, a converted value T (i) ′ on a straight line corresponding to the arbitrary measured voltage, The conversion value T (n + 1) ′ on the straight line corresponding to the measured voltage in the middle of the two sections and the difference Tz between the conversion value on the curve are calculated from the corresponding data, and the conversion value T (i on the straight line is calculated. ) 'Is corrected by an error Δt, The intermediate measurement voltage of the two sections with a quadratic function curve with the zero point of the XY axis, converted value on the straight line corresponding to an arbitrary measurement voltage T (i) 'and Part 2
A quadratic function curve calculating means for calculating the error ΔT from the value on the quadratic function curve from the difference Tz.

Further, according to the measurement data processing method of the present invention, a voltage value of a measured value which changes in a curve according to a change of a control amount is measured, and data corresponding to a converted value corresponding to the measured voltage at regular intervals are measured. Is stored in advance, the interval between adjacent measured voltages at equal intervals is defined as one section, and the measured voltages at both ends of a section including an arbitrary measured voltage measured and a section following the section are defined as the above. When connected by a straight line on a curve, the converted value T (i) ′ on the straight line corresponding to an arbitrary measured voltage
And the difference Tz between the converted value T (n + 1) ′ on the straight line corresponding to the measured voltage in the middle of the two sections and the converted value on the curve are calculated from the stored correspondence data. Using a quadratic function curve in which the voltage is a zero point on the XY axes, the converted value T (i) ′ on the straight line corresponding to an arbitrary measured voltage
Is calculated from the difference Tz, and the conversion value T (i) ′ on the straight line is calculated as the error Δ
It is characterized in that a correction operation is performed using t.

[0010]

In the measurement data processing apparatus according to the present invention having such a means, the two-section broken line calculating means determines whether an arbitrary measurement voltage input from the measurement means is divided into a section including the measurement voltage and two sections adjacent thereto. Assuming a straight line based on the measured voltages at both ends, a converted value T (i) ′ on the straight line corresponding to an arbitrary measured voltage and a converted value T (n + 1) ′ on a straight line corresponding to a measured voltage in the middle of two sections. And the difference Tz between the above and the converted value on the curve.

Then, the quadratic function curve calculating means uses a quadratic function curve with the measured voltage in the middle of the two sections as a zero point on the XY axes to calculate a converted value T corresponding to an arbitrary measured voltage.
(I) 'calculates an error ΔT between the value on the quadratic function curve from the difference Tz, and furthermore, the two-section broken line calculating means calculates a converted value T (i)' corresponding to the arbitrary measured voltage by an error. The output is corrected by ΔT.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The measurement data processing method according to the present invention will be described in the measurement data processing device. FIG. 1 is a block diagram showing one embodiment of a measurement data processing device according to the present invention. In FIG. 1, a measuring means 1 amplifies a DC measurement voltage corresponding to a control amount by a temperature sensor (not shown), for example, a thermocouple or a resistance temperature detector, or converts the voltage into a digital amount by A / D conversion and performs measurement described later. It is a known device that outputs the voltage E (i), and is connected to the two-section broken line calculation means 3 and the quadratic function curve calculation means 5.

As shown in FIG. 2, the data storage means 7 measures the measured voltages E (n), E (n + 1), E (n + 1), which are measured in advance at a constant voltage interval (EM), as shown in FIG.
E (n + 2) ... and the corresponding temperature (converted value) T
A plurality of conversion tables of (n), T (n + 1), T (n + 2)... Are stored as corresponding data tables. Note that the solid line in FIG. 2 is a temperature curve with respect to the measured voltage.

In addition, the data storage means 7 stores E (n + 1) and E (n + 1) between adjacent measurement voltages E (n) and E (n + 1).
(N + 2)... Are defined as one section, and two sections are measured in accordance with an instruction from the two-section broken line calculating means 3, including a section including an arbitrary measurement voltage E (i) and a continuous section adjacent thereto. Voltages E (n), E (n + 1), E (n + 2) ...
And the corresponding temperatures T (n), T (n + 1), T (n
+2)... To the two-section broken line calculating means 3.

The two-section broken line calculating means 3 calculates the measurement voltages E (n), E (n + 1), E (n) for an arbitrary measurement voltage E (i) for an interval including the arbitrary measurement voltage E and for two intervals adjacent thereto.
+2)... And corresponding temperatures T (n) and T (n +
1), T (n + 2)... Are input from the data storage means 7, and a straight line connecting the measured voltages E (n) and E (n + 2) at both ends of the two sections is defined as It has the functions assumed above.

The two-section broken line calculating means 3 calculates a temperature T on a straight line corresponding to the measured voltage E (n + 1) which is an intermediate point of the two sections.
(N + 1) ′ and the temperature T corresponding to the measured voltage E (n + 1)
(N + 1) and any measured voltage E (i)
A function of calculating a temperature T (i) ′ on a straight line corresponding to the above equation, adding an error ΔT described later to the temperature T (i) ′, correcting the temperature, and outputting a measured temperature T (i) with respect to E (i). have.

The quadratic function curve calculating means 5 receives the measured voltage E from the data storage means 7 via the two-section broken line calculating means 3.
(N), E (n + 1), E (n + 1), E (n + 2) ...
... and the corresponding temperatures T (n), T (n + 1), T
(N + 2)..., And as shown in FIG.
The curve between (n) and E (n + 2) is replaced by a quadratic function curve with the measured voltage E (n + 1) in the middle of the two sections as the zero point on the XY axis, It has a function of calculating the difference ΔT between the temperature T (i) ′ and the value on the quadratic function curve and outputting the calculated difference ΔT to the two-section broken line calculating means 3.

The two-section broken line calculating means 3 adds and corrects an error ΔT to a temperature T (i) ′ on a straight line corresponding to an arbitrary measured voltage E (i), and calculates a measured temperature T (E) for E (i).
(I) is output approximately.

Next, the measurement data processing method of the present invention will be described with reference to FIGS. In FIG. 2, measured voltages E (n) and E (n + 1)
The temperature T (i) for any measured voltage E (i) between
As shown in the following (a) to (f), it can be obtained approximately with high accuracy.

(A) First, the section n including the measured voltage E (i) is calculated by the following section (2) by the two-section broken line calculating means 3,
The measured voltages E (n), E (n + 1), E (n + 2)... And the corresponding temperatures T (n), T (n + 1), T (n +
2) ... are taken into the two-section broken line calculating means 3. n = [E (i) −E (0)] / EM (2) [where E (0) is the initial fixed voltage when n = 0, and EM is the equal voltage width of the section. ]

(B) Next, the two-section broken-line calculating means 3 measures the measured voltages E (n) and E in two sections as shown in FIG.
A straight line connecting (n + 2) is assumed on the curve, and a temperature T (n + 1) ′ on the straight line with respect to the measured voltage E (n + 1), which is an intermediate point of the straight line, is obtained, and the temperature T with respect to the measured voltage E (n + 1) is obtained. The difference Tz between (n + 1) and the temperature T (n + 1) ′ is calculated from the following equation (3). Tz = T (n + 1) ′ − T (n + 1) = [T (n + 2) −T (n)] / [E (n + 2) −E (n)] × [E (n + 1) −E (n)] + T (N) -T (n + 1) (3)

(C) Further, the quadratic function curve calculating means 5 measures the measured voltages E (n) and E (n +
The curve portion between 2) is replaced with a quadratic function f (x) as shown in FIG. 3 by the following equation (4) using the difference Tz and the voltage interval EM. f (x) = (Tz / EM ² ) X ² (4)

(D) Further, the value is substituted into the quadratic function of the equation (4) by the quadratic function curve calculating means, and the difference ΔT between the difference Tz and the quadratic function curve is obtained. This is shown by equation (5). ΔT = Tz− (Tz / EM ² ) [E (i) −E (n) −EM] ² (5)

(E) Next, a value T (i) ′ obtained by linearly approximating the measured voltage E (i) with a dashed line is obtained from the following equation (6). T (i) ′ = {[T (n + 2) −T (n)] / [E (n + 2) −E (n)]} × [E (i) −E (n)] + T (n) (6) )

(F) Then, by subtracting ΔT from T (i) ′ using the following equation (7) in the two-section broken line calculating means 3, the calculated T (i) can be approximately calculated. T (i) = T (i) ′ − ΔT (7)

As described above, according to the present invention, with respect to the measurement voltage that changes in a curve, adjacent measurement voltages E at equal intervals are used.
(N) and E (n + 1), E (n + 1) and E (n + 2)
... Are defined as one section, and a section including an arbitrary measurement voltage E (i) and measurement voltages at both ends of two consecutive sections are connected by a straight line, and correspond to an arbitrary measurement voltage E (i). The temperature T (i) ′ on the straight line and the difference Tz between the temperature T (n + 1) ′ on the straight line corresponding to the intermediate point E (n + 1) of the two sections and the temperature T (n + 1) on the curve are calculated. And a temperature T corresponding to an arbitrary measured voltage E (i) using a quadratic function curve in which an intermediate point E (n + 1) of the two sections is set to a zero point on the XY axis.
(I) The error ΔT between '′ and the value on the quadratic function curve
z, the temperature T (i) ′ with respect to the voltage E (i)
And the error ΔT is added and corrected and output as the temperature T (i) with respect to E (i).
A highly accurate conversion temperature T (i) is obtained with respect to (i).

In addition, the above-described equations (1) to (7) are stored in advance, and the measured voltages E at regular intervals as in the prior art are measured.
(N), E (n + 1), E (n + 1), E (n + 2) ...
Can be used for highly accurate correction, so that it is not necessary to measure and store the measurement voltage at narrow measurement intervals, and the storage capacity can be saved even if the measurement accuracy is higher than before.

FIG. 4 shows the K-type thermocouple from 0 to 130.
This is a comparison of the measurement accuracy when measuring in the range of 2.9 ° C. with an equal-interval voltage of every 1500 μV (about 40 ° C.) to the conventional example. The horizontal axis shows the measurement temperature, and the vertical axis shows the measurement error with respect to the true value.
0.1 ° C. is indicated. In FIG. 4, the solid line is a measurement error according to the present application, and the dotted line is a measurement error according to the conventional example. Both the solid line and the dotted line have an error of 0 at regular intervals, and the point is a data portion storing voltage versus temperature data. It is.

According to FIG. 4, the dotted line of the conventional example has a large error as a whole, and especially at the lower and upper parts of the measurement range.
In some cases, the measurement error is very large and exceeds ± 0.1 ° C. On the other hand, in the present application, although a relatively large error occurs in the lower part of the measurement range, it can be seen that the measurement data can be processed with a relatively small error as a whole.

FIG. 5 is a graph showing the T-type thermocouple in the range of 0 to 4;
The measurement accuracy when the measurement is performed at an equal interval voltage of 1500 μV (approximately 40 ° C.) in the range of 02 ° C. is compared with the conventional example, and similarly, the error is suppressed to be smaller than the conventional example. I understand.

[0031]

As described above, the measurement data processing apparatus according to the present invention comprises a measuring means for measuring the voltage of a measured value which changes in a curve, and the correspondence between the measured voltage at equal intervals and the corresponding converted value. A data storage means for storing data in advance, and an interval between adjacent measurement voltages at equal intervals are defined as one section, and a section including an arbitrary measurement voltage and two sections continuous with the measurement voltage at both ends are plotted on the curve. Is connected by a straight line, the converted value T (i) ′ on the straight line corresponding to the arbitrary measured voltage, and 2
Conversion value T (n on a straight line corresponding to the measured voltage in the middle of the section
+1) ′ and the difference Tz between the conversion value on the curve and the conversion value T on the straight line.
(I) Two-section broken line calculating means for correcting '′ with an error Δt, and the above-mentioned straight line corresponding to an arbitrary measured voltage using a quadratic function curve in which a measured voltage in the middle of the two sections is set to a zero point on the XY axis. And a quadratic function curve calculating means for calculating the error ΔT between the above converted value T (i) ′ and the value on the quadratic function curve from the difference Tz. Further, in the measurement data processing method of the present invention, for the measurement voltage that changes in a curve,
Data corresponding to the conversion values corresponding to each equal interval is stored in advance, and each interval between adjacent measurement voltages at each equal interval is defined as one section, and both ends of a section including an arbitrary measurement voltage and two sections continuous with this section Are connected by a straight line, the converted value on the straight line corresponding to an arbitrary measured voltage, the converted value T (n + 1) ′ on the straight line corresponding to the midpoint of the two sections, and the converted value T on the curve
The difference Tz from (n + 1) is calculated from the stored correspondence data, and a quadratic function curve in which the midpoint of the two sections is the zero point on the XY axis is used. An error ΔT is calculated from the difference Tz, the converted value T (i) ′ is corrected by the error ΔT, and is output as a converted value T (i) for an arbitrary measured voltage. for that reason,
The measurement value error corresponding to an arbitrary measurement voltage can be reduced, and the number of stored measurement voltages to be measured in advance does not increase. Therefore, even if the function is increased as in a recent control device, and a large number of thermocouples and resistance temperature detectors are configured to be exchangeable and connectable, and the switching operation can be performed with one touch by the installed software or the like, the measurement of the present invention can be performed. If a data processing device is used, it is possible to measure with the same or higher accuracy as before without increasing the storage capacity, and it is possible to cope with miniaturization and high accuracy of the control device,
The storage capacity can be used for data other than measurement data,
Other functions can be enhanced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a measurement data processing device according to the present invention.

FIG. 2 shows a measured voltage and a converted value (temperature) for explaining the operation of the measured data processing apparatus of FIG. 1 and the method according to the present invention.
FIG. 4 is a characteristic diagram showing the relationship of FIG.

FIG. 3 is a diagram for explaining a quadratic function curve in the measurement data processing device and method according to the present invention.

FIG. 4 is a diagram showing a measurement error by a measurement data processing apparatus and method of the present invention together with a conventional example.

FIG. 5 is another diagram showing a measurement error by the measurement data processing apparatus and method of the present invention together with a conventional example.

FIG. 6 is a diagram illustrating a method of converting a measured voltage by a conventional measurement data processing device into a corresponding converted value (temperature).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measurement means 3 2-section broken line calculation means 5 Quadratic function curve calculation means 7 Data storage means

Claims (2)

(57) [Claims] 1. A measuring means for measuring a voltage of a measured value which changes in a curve according to a change of a control amount, and a data storing means for storing in advance corresponding data of conversion values corresponding to the measured voltage at regular intervals. The interval between the adjacent measurement voltages at equal intervals is defined as one section, and the measurement voltages at both ends of a section including an arbitrary measurement voltage from the measurement means and a section following the section are defined on the curve. , A conversion value T (i) ′ on the straight line corresponding to the arbitrary measurement voltage and a conversion value T (n + n) on the straight line corresponding to the measurement voltage in the middle of the two sections.
1) a two-segment broken line calculating means for calculating a difference Tz between the converted value on the curve and the converted value on the curve from the corresponding data, and correcting the converted value T (i) 'on the straight line with an error Δt; Using a quadratic function curve in which the measured voltage in the middle of the section is the zero point on the XY axes, the converted value T (i) ′ on the straight line corresponding to the arbitrary measured voltage and the quadratic function curve To calculate the error ΔT from the value of
A measurement data processing device comprising: a quadratic function curve calculating means. 2. A voltage measurement is performed on a measured value that changes in a curve according to a change in a control amount, data corresponding to a converted value corresponding to the measured voltage at equal intervals is stored in advance, and adjacent data at equal intervals are stored. The interval between the matched measurement voltages is defined as one section, and when the measurement voltages at both ends of a section including an arbitrary measurement voltage measured and a section continuous with the measurement voltage are connected by a straight line on the curve, the arbitrary , The conversion value T (n + 1) ′ on the straight line corresponding to the measured voltage in the middle of the two sections, and the conversion value on the curve. From the stored correspondence data, and using a quadratic function curve with the measured voltage in the middle of the two sections as a zero point on the XY axes, using the quadratic function curve corresponding to the arbitrary measured voltage The error ΔT between the converted value T (i) ′ and the value on the quadratic function curve is Calculated from the difference Tz, which correction operation using the error Δt of the straight line of the conversion value T (i) ', the measurement data processing method characterized by.