CN100533087C - Error compensation method of high-precision pressure sensor - Google Patents

Abstract

The invention provides an error compensation model and an algorithm of a high precision pressure transducer. The invention uses an oven and a standard pressure source to collect the output data of the transducer under N temperature spots and M pressure spots to constitute an N*M matrix; a sensor output mathematical model is established, and the thermal compensation coefficients a(T), b(T), c(T) of the sensor output function, and the electrical null of the sensor under different temperatures are fit according to the collected data: U0(T)=f(T), and the parameters are written into a microprocessor; when the invention is used, the electrical null U0 of the restoration record transducer is clicked at the time point of zero pressure, and U0(T) is calculated through the information of the collected temperatures (T), and the time shift of the sensor within the use and compensation intervals is calculated out: delta=U0-U0(T); the microprocessor calculates the conditioner microprocessor output by collecting the information of the output signal (U) of the temperature transducer (T) and the pressure transducer according to the compensation formula: P=a(T)(U-delta)<2>+b(T)(U-delta)+c(T). The invention combines the design and production technologies of pressure sensors, the signal conditioning technology and the computer technology to achieve rectification of the pressure transducer in the wide temperature range. The pressure signal characteristic and effect is excellent.

Description

The error compensating method of high-precision pressure sensor

Technical field

The present invention relates to the error compensating method of high-precision pressure sensor, is the application of modern advanced signal processing technology in art of pressure sensors, helps improving the output characteristics of pressure transducer.

Technical background

Pressure transducer is a measuring element commonly used in the engineering, because the influence of temperature and manufacturing process itself, its output characteristics can be offset, and causes the inaccurate of measurement result, and main have non-linear, zero-bit and sensitivity temperature drift, three kinds of errors of zero-bit time drift.

Traditional error correcting method for pressure sensor mainly contains: modes such as connection in series-parallel resistance, thermistor network, resistance laser trimming, repairing of method transferred principle basic identical during these were several, all be to adopt analog form that accent is repaiied in the electric bridge bridge resistance of pressure transducer, to realize the unanimity of bridge resistance characteristic.This method technical maturity, but exist following deficiency: it is loaded down with trivial details 1, to repair the accent process; 2, once can only repair accent to a sensor, production efficiency is low; 3, repair the temperature adjustment district and fix, can only repair accent, repair and transfer effect to be difficult to satisfactory a certain specific warm area.4, can only once repair accent, in use, when the zero-bit time of origin drifts about, can not revise once more.

Summary of the invention

Along with application scenarios such as industry control are more and more higher to measuring accuracy and reliability requirement, modern signal conditioning technology, computer technology, mechanics of communication also are used to improve the performance of pressure transducer more and more.The present invention is exactly in conjunction with the design of pressure-sensing device and production technology, signal condition technology, computer technology, and a kind of novel high-precision pressure sensor error compensating method is provided, and has remedied above deficiency.

Technical scheme of the present invention is achieved in that a kind of error compensating method of high-precision pressure sensor, this error compensation comprise pressure sensor temperature drift compensation, nonlinear compensation and the time float compensation, the output signal of calibration sensor when zero-bit and full scale may further comprise the steps:

(1) use baking oven and standard pressure generator to gather N temperature spot, the output data of M spot pressure lower sensor constitutes N*M rank matrix;

(2) set up sensor output mathematical model P=aU ²+ bU+c, according to the output signal U and the plus-pressure value P of institute of each temperature spot lower sensor of gathering, the temperature compensation coefficient a (T) of match sensor output function, b (T), c (T) and sensor be zero-bit output U under different temperatures ₀(T)=f (T), and parameter write microprocessor;

When (3) using, clicks when zero pressure and reset, the zero-bit of record sensor is exported U ₀,, and calculate U by collecting temperature information T ₀(T), so calculate sensor use with compensator section in time drift amount Δ=U ₀-U ₀(T);

(4) microprocessor is by the output signal U of collecting temperature information T and pressure transducer, and according to the output that compensation formula calculates conditioning back microprocessor, compensation formula is as follows:

P＝a(T)(U-Δ) ²+b(T)(U-Δ)+c(T)

Wherein: P is the output of microprocessor, institute's applied pressure value;

U is the output signal of sensor under pressure P;

A (T), b (T), c (T) is the temperature compensation coefficient of sensor output function;

U ₀(T) be that sensor is in compensation zero-bit output level constantly;

U ₀The zero-bit output level of carving in use for sensor;

Δ is the time drift amount of sensor in use and compensator section.

Useful technique effect of the present invention is: 1. the sensor calibration that can realize (as-40 ℃～+ 85 ℃) in the wide warm area; 2. the pressure signal characteristic effect of microprocessor output is splendid; 3. compensation way is simple, can proofread and correct sensor in real time by human-computer interaction interface.

Description of drawings

Fig. 1 is the synoptic diagram of error compensating method in compensation process of high-precision pressure sensor of the present invention;

Fig. 2 is the error compensating method synoptic diagram in use of high-precision pressure sensor of the present invention.

Embodiment

That realizes that this invention needs disposes computing machine, microprocessor, pressure transducer, temperature sensor, standard pressure generator and baking oven.Established standards pressure source and baking oven, the output information of gathering pressure transducer and temperature sensor constitutes N*M rank matrix, utilizes mathematics manipulation software MATLAB that data are handled in computing machine, calculates the parameter of compensation and is written in the microprocessor.

(1) below in conjunction with Fig. 1 the specific implementation of the present invention at compensation process is described:

The error compensating method of high-precision pressure sensor, this error compensation comprise pressure sensor temperature drift compensation, nonlinear compensation and the time float compensation, the output signal of calibration sensor when zero-bit and full scale, performing step is as follows:

1. use baking oven and standard pressure generator to gather N temperature spot, the output data of M spot pressure lower sensor constitutes N*M rank matrix;

Table 1: the original sampling data matrix (unit: mv) of sensor

2. use the MATLAB mathematical software to carry out data processing, obtain pressure transducer error compensation parameter:

(1) under each temperature spot, signal of sensor U and the plus-pressure value P of institute are carried out quadratic fit, P=aU ²+ bU+c gets penalty coefficient a, b, and c:

For example sensor is at-40 ℃, and the original output signal of sensor is during 0:10:100Kpa:

-4.20

10.60

25.69

40.57

55.44

70.30

85.12

99.90

114.64

129.35

144.03

Polyfit (U, P, 2) obtains in the use MATLAB curve fitting tool box:

P＝0.00005020249076U ²+0.66726311312795U+2.84690180116907

A=0.00005020249076 then, b=0.66726311312795, c=2.84690180116907.

In like manner can obtain the penalty coefficient a of other temperature spots, b, c:

a＝[0.00005020249076 0.00004886931202 0.00004760437299 0.00004695455956

0.00004599382927 0.00004676468308 0.00004341306162 0.00004307419716

0.00004532477475 0.00004171712066 0.00004437022972 0.00003314121405

0.00003148611899 0.00003141718418 -0.00000294240081 0.00002587112156

0.00002780947200 0.00002031863796]；

b＝[0.66726311312795 0.67688788229000 0.68626404709359 0.69503760748426

0.70360959850094 0.71208167609031 0.72148147475641 0.73021524486702

0.73883160408613 0.75621768858100 0.77268929925359 0.79167076852924

0.80893296324179 0.82639243718168 0.84620196129366 0.85938501191458

0.87782815901665 0.88695508606735]；

c＝[2.84690180116907 2.42115171922496 2.04420055831314 1.71706228748298

1.42273730821736 1.15926621355972 0.89450566144025 0.65148659984389

0.44742988476994 0.10814541049880 -0.15925923462867 -0.34707444538728

-0.47032044667003 -0.53619482236170 -0.45213754309480 -0.33776088557796

-0.19122032311449 -0.14693094145804]；

(2) in-40 ℃～+ 85 ℃ warm area scopes with penalty coefficient a, b, c fit to the quadratic function of temperature information, polyfit (T, a, 2:

a＝1.0e-004*(-0.00000374525545*T ²-0.00252780686988*T+0.41701845002545)；

b＝-0.00000027526204*T ²+0.00176333916650*T+0.73887048302399；

c＝0.00040424920254*T ²-0.04067961162223*T+0.47905726271458.

(3) pressure signal of compensation back microprocessor output:

P＝aU ²+bU+c

(4) effect that the checking compensation reaches on non-match temperature spot, gathered the original signal of sensor respectively-27.5 ℃ ,-12.5 ℃ and 25 ℃ sensor outputs:

Bring temperature information T and signal of sensor U into compensation formula, the pressure signal of microprocessor output is as follows:

From the data of checking as can be seen, having incorporated pressure signal that the microprocessor of temperature information and sensor voltage output information exports, compare the precision that reaches with standard pressure generator be 0.05%, and compensation effect is splendid.

(5) compensation of floating during transducer zeroing

By the five equilibrium temperature range, utilize the standardization polynomial method that the zero-bit of sensor is fitted to the function of temperature information, concrete operations are as follows:

The zero-bit of sensor under different temperatures is output as:

T/℃	-40	-30	-20	-10	0	10	20	30	40	50	60	70	80	85
															U 0(T)	-4.20	-2.97	-2.01	-1.22	-0.60	-0.13	0.24	0.47	0.60	0.67	0.52	0.42	0.25	0.20

For reducing the inversion operation amount of matrix, the spy is divided into temperature in-40～0 ℃ and 0～85 ℃ of two interval, and the function that utilizes the standardization polynomial method to simulate is located 0 ℃ of temperature breakpoint continuously.Draw the polynomial expression best results that five temperature spot quartern temperature ranges simulate by checking in addition.

Concrete method is achieved as follows in warm area-40～0 ℃:

A＝[1 1 1 1

2 2^2 2^3 2^4

3 3^2 3^3 3^4

4 4^2 4^3 4^4]

B＝inv(A)*[-0.62-1.41-2.37-3.60]′

C＝B.*[(-10)^-1(-10)^-2(-10)^-3(-10)^-4]

Obtain fitting coefficient: C=0.05100000000000

-0.00130833333333

-0.00002500000000

-0.00000041666667

Write out the function of sensor zero point output and temperature:

U ₀(T)＝-0.60+0.05100000000000 T-0.00130833333333 T ²-0.00002500000000 T ³-0.00000041666667 T ⁴

With T=[-40-30-20-100] bring into and verify that fitting effect gets:

-4.20000000852800 -2.97000000269700 -2.01000000053200

-1.22000000003300 -0.60000000000000

Can see with original data quite approachingly, satisfy the requirement do high-precision pressure sensor.

Can obtain the function of 0～85 ℃ of sensor zero point output of warm area and temperature equally:

U ₀(T)＝-0.60+0.05204166666667T-0.00040937500000T ²-0.00000572916667T ³+0.00000005468750T ⁴

During use, reset by click, note the zero-bit output U of sensor at zero pressure ₀Then the drift value of sensor in compensation and usage time interval is: Δ=U ₀-U ₀(T)

The pressure signal output function of the microprocessor that has floated when (5) having compensated transducer zeroing is:

P＝a(T)(U-Δ) ²+b(T)(U-Δ)+c(T)

(2) in conjunction with Fig. 2 the present invention's operating process in use is described: at first reset the zero-bit output U of record sensor in the zero pressure click ₀, and collecting temperature information T, calculate the drift value Δ of sensor in compensation and usage time interval according to formula.When exerting pressure, microprocessor calculates the applied pressure P of institute by the output signal U (being output voltage signal) and the temperature information T of pick-up transducers.

Claims (1)

1, a kind of error compensating method of high-precision pressure sensor, it is characterized in that, this error compensation comprise pressure sensor temperature drift compensation, nonlinear compensation and the time float compensation, the output signal of calibration sensor when zero-bit and full scale, this method performing step is as follows:

(1) use baking oven and standard pressure generator to gather N temperature spot, the output data of M spot pressure lower sensor constitutes N*M rank matrix;

(2) set up sensor output mathematical model P=aU ²+ bU+c, according to the output signal U and the plus-pressure value P of institute of each temperature spot lower sensor of gathering, the temperature compensation coefficient a (T) of match sensor output function, b (T), c (T) and sensor be zero-bit output U under different temperatures ₀(T)=f (T), and parameter write microprocessor;

When (3) using, clicks when zero pressure and reset, the zero-bit of record sensor is exported U ₀, by collecting temperature information T and calculate U ₀(T), so calculate sensor use with compensator section in time drift amount Δ=U ₀-U ₀(T);

(4) microprocessor is by the output signal U of collecting temperature information T and pressure transducer, and according to the output that compensation formula calculates conditioning back microprocessor, compensation formula is as follows:

P＝a(T)(U-Δ) ²+b(T)(U-Δ)+c(T)

Wherein: P is the output of microprocessor, institute's applied pressure value;

U is the output signal of sensor under pressure P;

A (T), b (T), c (T) is the temperature compensation coefficient of sensor output function;

U ₀(T) be that sensor is in compensation zero-bit output level constantly;

U ₀The zero-bit output level of carving in use for sensor;

Δ is the time drift amount of sensor in use and compensator section.

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