CN105527056A - Temperature reference-based pressure compensation calibration method - Google Patents

Abstract

The invention relates to the field of precision calibration and temperature compensation for pressure acquisition instruments, and particularly relates to a temperature reference-based pressure compensation calibration method. The method comprises the following steps: a temperature range is divided according to the temperature of an electronic device using environment and a digital quantity at the output end of an AD conversion circuit; pressure calibration points are determined in an equal division method, a pressure range is divided, and the change quantity between adjacent pressure calibration points is calculated; and a temperature change correction value is calculated, and compensation calibration is carried out on the temperature. Through using the method of the invention, through calibration of a short time, the purpose of realizing target measurement precision by an overall instrument temperature range is achieved, a large quantity of production time and production cost are saved, and a high-precision instrument product can be produced by using a low-cost sensor and a low-cost electronic device.

Description

A kind of pressure compensation calibration steps based on temperature reference

Technical field

The present invention relates to the calibration of pressure acquisition class accuracy of instrument and temperature compensation field, specifically a kind of pressure compensation calibration steps based on temperature reference.

Background technology

In data acquisition application, collecting actual physical amount is accurately a highly difficult problem, and we are by the summary of practical problems, the analysis of data, and our method of successive optimization, makes collection result more and more close to actual value.

For the collection of pressure data, be usually made up of two parts, electron device part and Sensor section.Sensor section realizes the conversion of physical signalling to electric signal, and electron device part realizes the conversion of analog quantity to digital quantity.But this two parts device all can change along with the change of environment temperature, causes image data to occur deviation.

Traditional method all will carry out the temperature compensation of hardware to two parts, but, no matter be sensor or electron device, in the middle of the process of hardware implementing temperature compensation, realize that difficulty is large, later stage adjustment difficulty, and cost cost be high.

Summary of the invention

For the deficiencies in the prior art, the present invention, by summarizing to the data in R&D process, proposes a kind of simple and practical compensation calculation method, through simply demarcating, in conjunction with computing method herein, can realize eliminating error, obtaining the object of aimed at precision.

The technical scheme that the present invention is adopted for achieving the above object is: a kind of pressure compensation calibration steps based on temperature reference, comprises the following steps:

Step 1: according to the temperature of electron device environment for use and the digital quantity of A/D convertor circuit output terminal, divides temperature range;

Step 2: by halving method determination pressure calibration point, segmentation pressure range, and calculate the variable quantity between adjacent pressure calibration point;

Step 3: accounting temperature change modified value, compensates calibration to pressure.

The partition process of described temperature range is:

$\frac{|D_{\mathrm{Pa}}-D_{\mathrm{Pb}}|}{2}\≤D_F*d_{\mathrm{pre}}$

Wherein: D _pafor the demarcation digital quantity of temperature spot a under pressure P condition; D _pbfor the demarcation digital quantity of temperature spot b under pressure P condition; D _ffor the full scale digital quantity under normal temperature condition; d _prefor accuracy of instrument; P is pressure range maximum of points; A, b are adjacent temperature spot under uniform pressure.

The computation process of described pressure range is:

$\frac{D_{\mathrm{Ta}}-D_{\mathrm{Tb}}}{2}\≤D_F*d_{\mathrm{pre}}$

Wherein: D _tafor temperature T condition presses down the demarcation digital quantity of force a; D _tb-temperature T condition presses down the demarcation digital quantity of force b; D _ffor the full scale digital quantity under normal temperature condition; d _prefor accuracy of instrument; T is Instrument use ambient boundary temperature spot; A, b are adjacent spot pressure at identical temperature.

The computation process of the variable quantity between described adjacent pressure calibration point is:

${\mathrm{\δ}}_{(n-1,n)}=\frac{P_n-P_{n-1}}{D_n-D_{n-1}}$

Wherein: δ _{(n-1, n)}for under a certain temperature spot, the variable quantity between adjacent pressure calibration point; P _nfor the higher value of nominal pressure value, P _n-1for the smaller value of nominal pressure value; D _nfor demarcating the higher value of digital quantity, D _n-1for demarcating the smaller value of digital quantity.

The computation process of described temperature variation modified value is:

$d_n=\frac{D_t-D_{t-1}}{{\mathrm{\Δ}}_t}$

Wherein: d _nfor under uniform pressure, between different temperatures value, the digital quantity variable quantity of same temperature change; D _tfor the demarcation digital quantity at larger temperature spot place, D _t-1for the demarcation digital quantity at less temperature spot place; Δ _tfor the difference of temperature variation.

The present invention has following beneficial effect and advantage:

By using method as herein described, through the demarcation of short time, just can reach the object of instrument total temperature scope realize target measuring accuracy, a large amount of production times and production cost can be saved like this.Also can use sensor and the electron device of lower cost, produce the instrument product of degree of precision.

Accompanying drawing explanation

Fig. 1 is method step process flow diagram of the present invention;

Fig. 2 is tensimeter real time data production process figure of the present invention;

Fig. 3 is that temperature of the present invention divides schematic diagram;

Fig. 4 is pressure calibration of the present invention some schematic diagram;

Fig. 5 is the nominal data curve synoptic diagram under different temperatures of the present invention.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in further detail.

Be illustrated in figure 2 tensimeter real time data production process figure, first clear and definite designed manometric range ability is wanted to be how many (as 0-6MPa), then will the output signal range (as: 0-80mV) of corresponding institute's employing sensor, the simulating signal (as 0-0.8VDC) after amplifying (as: 10 times) will be input to A/D convertor circuit.The collection terminal of A/D convertor circuit will obtain the digital quantity signal (as: 0-40000) of a fixed range.In the Real-time Collection process of force value, only need can calculate current force value according to gathered digital quantity.Computing formula is as follows:

$P_C=\frac{P_H-P_L}{D_H-D_L}(D_C-D_L)+P_L$

Wherein:

P _c-current pressure values, D _c-current the digital quantity collected;

P _hthe force value that-nominal data height point is corresponding, P _lthe force value that-nominal data low spot is corresponding;

D _hthe digital quantity that-nominal pressure height point is corresponding, D _lthe digital quantity that-nominal pressure low spot is corresponding.

Be illustrated in figure 1 method step process flow diagram of the present invention, this method realizes temperature compensation and the error concealment of pressure acquisition mainly through three steps.

The first step: the division realizing temperature spot.

Be illustrated in figure 3 temperature and divide schematic diagram.

The division of temperature should follow certain principle.Mainly see the hardware temperatures compensation range that selected pressure transducer carries out in process of production, the interval of the temperature spot selected within the scope of hardware compensating can be wider, and in uncompensated temperature range, the temperature interval of selection wants narrower.Select the size at interval, can be adjusted by sensor and the test data of circuit board and the precision of designed instrument.According to the environment for use temperature (as:-40 ~+85 DEG C) of designed instrument, test respectively at high and minimum boundary temperature point, read the digital quantity of AD output terminal, its maximum deviation should follow following formula:

$\frac{|D_{\mathrm{Pa}}-D_{\mathrm{Pb}}|}{2}\≤D_F*d_{\mathrm{pre}}$

Wherein:

D _pathe demarcation digital quantity of temperature spot a under-pressure P condition;

D _pbthe demarcation digital quantity of temperature spot b under-pressure P condition;

D _funder-normal temperature 25 DEG C of conditions, full scale digital quantity, d _pre-accuracy of instrument.

Note: P is pressure range maximum of points (as: 0 ~ 6MPa gets 6MPa), and a, b are adjacent temperature spot under uniform pressure.

For the sensor of MPM281 model, sensor own temperature compensation range is-10 DEG C ~ 80 DEG C, and technical target of the product is-40 DEG C ~ 85 DEG C.Aimed at precision is 0.5 grade, can select+70 DEG C ,+25 DEG C ,-15 DEG C ,-25 DEG C ,-35 DEG C as the temperature spot demarcated.

Second step: the selection of pressure calibration point and the determination of variable quantity.

The selection of pressure calibration point adopts halving method, gradually decile, finally determines the quantity of Along ent.First select range smallest point, range mid point, range maximum of points totally 3 points, measure the value of the digital quantity of its AD output terminal respectively, then bring formula below into:

$\frac{D_{\mathrm{Ta}}-D_{\mathrm{Tb}}}{2}\≤D_F*d_{\mathrm{pre}}$

Wherein:

D _ta-temperature T condition presses down the demarcation digital quantity of force a;

D _tb-temperature T condition presses down the demarcation digital quantity of force b;

D _funder-normal temperature (25 DEG C) condition, full scale digital quantity, d _pre-accuracy of instrument.

Note: T is Instrument use ambient boundary temperature spot (as:-40 ~+85 DEG C, gets-40 DEG C ,+85 DEG C), and a, b are adjacent spot pressure at identical temperature.

Be illustrated in figure 4 pressure calibration point schematic diagram.

For 0 ~ 6MPa range, the design objective of 0.5 grade, 0MPa, 1.5MPa, 3MPa, 4.5MPa, 6MPa can be selected as pressure calibration point.Variable quantity between every two calibration points can obtain with formula below:

${\mathrm{\δ}}_{(n-1,n)}=\frac{P_n-P_{n-1}}{D_n-D_{n-1}}$

Wherein:

δ _{(n-1, n)}for under a certain temperature spot, the variable quantity between two pressure calibration points;

P _nfor the higher value of nominal pressure value, P _n-1for the smaller value of nominal pressure value;

D _nfor demarcating the higher value of digital quantity, D _n-1for demarcating the smaller value of digital quantity.

3rd step: the compensation realizing temperature.

Be illustrated in figure 5 the nominal data curve synoptic diagram under different temperatures, at fixing temperature spot, the collection result of force value is an approximate straight line.Under the collection result of different temperature spots is described in the same coordinate system, not ideal parallelism line, but form similar trumpet type.At the pressure cut-point place chosen respectively as two reference point calculated, the ratio of its difference and temperature is as the modified value of temperature variation.

Between two calibration curves, under uniform pressure, the every changes delta of temperature _t(such as 1 DEG C), the computing formula of demarcating the variable quantity of digital quantity is:

$d_n=\frac{D_t-D_{t-1}}{{\mathrm{\Δ}}_t}$

Wherein:

D _nfor under uniform pressure, Δ between different temperatures value _tthe digital quantity variable quantity of (such as 1 DEG C);

D _tfor the demarcation digital quantity at larger temperature spot place, D _t-1for the demarcation digital quantity at less temperature spot place;

Δ _tfor the difference of temperature variation.

By using method as herein described, through the demarcation of short time, just can reach the object of instrument total temperature scope realize target measuring accuracy, a large amount of production times and production cost can be saved like this.Also can use sensor and the electron device of lower cost, produce the instrument product of degree of precision.

Claims (5)

1., based on a pressure compensation calibration steps for temperature reference, it is characterized in that: comprise the following steps:

Step 1: according to the temperature of electron device environment for use and the digital quantity of A/D convertor circuit output terminal, divides temperature range;

Step 2: by halving method determination pressure calibration point, segmentation pressure range, and calculate the variable quantity between adjacent pressure calibration point;

Step 3: accounting temperature change modified value, compensates calibration to pressure.

2. the pressure compensation calibration steps based on temperature reference according to claim 1, is characterized in that: the partition process of described temperature range is:

$\frac{|D_{\mathrm{Pa}}-D_{\mathrm{Pb}}|}{2}\≤D_F*d_{\mathrm{pre}}$

Wherein: D _pafor the demarcation digital quantity of temperature spot a under pressure P condition; D _pbfor the demarcation digital quantity of temperature spot b under pressure P condition; D _ffor the full scale digital quantity under normal temperature condition; d _prefor accuracy of instrument; P is pressure range maximum of points; A, b are adjacent temperature spot under uniform pressure.

3. the pressure compensation calibration steps based on temperature reference according to claim 1, is characterized in that: the computation process of described pressure range is:

$\frac{D_{\mathrm{Ta}}-D_{\mathrm{Tb}}}{2}\≤D_F*d_{\mathrm{pre}}$

Wherein: D _tafor temperature T condition presses down the demarcation digital quantity of force a; D _tb-temperature T condition presses down the demarcation digital quantity of force b; D _ffor the full scale digital quantity under normal temperature condition; d _prefor accuracy of instrument; T is Instrument use ambient boundary temperature spot; A, b are adjacent spot pressure at identical temperature.

4. the pressure compensation calibration steps based on temperature reference according to claim 1, is characterized in that: the computation process of the variable quantity between described adjacent pressure calibration point is:

${\mathrm{\δ}}_{(n-1,n)}=\frac{P_n-P_{n-1}}{D_n-D_{n-1}}$

Wherein: δ _{(n-1, n)}for under a certain temperature spot, the variable quantity between adjacent pressure calibration point; P _nfor the higher value of nominal pressure value, P _n-1for the smaller value of nominal pressure value; D _nfor demarcating the higher value of digital quantity, D _n-1for demarcating the smaller value of digital quantity.

5. the pressure compensation calibration steps based on temperature reference according to claim 1, is characterized in that: the computation process of described temperature variation modified value is:

$d_n=\frac{D_t-D_{t-1}}{{\mathrm{\Δ}}_t}$

Wherein: d _nfor under uniform pressure, between different temperatures value, the digital quantity variable quantity of same temperature change; D _tfor the demarcation digital quantity at larger temperature spot place, D _t-1for the demarcation digital quantity at less temperature spot place; Δ _tfor the difference of temperature variation.