CN114323134A - Temperature and pressure composite sensor and correction resolving method - Google Patents
Temperature and pressure composite sensor and correction resolving method Download PDFInfo
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- CN114323134A CN114323134A CN202111615536.0A CN202111615536A CN114323134A CN 114323134 A CN114323134 A CN 114323134A CN 202111615536 A CN202111615536 A CN 202111615536A CN 114323134 A CN114323134 A CN 114323134A
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Abstract
The invention belongs to the field of airborne sensors, and relates to a temperature and pressure composite sensor and a correction resolving method. The temperature and pressure composite probe comprises a pressure sensitive element and a temperature sensitive element, the temperature and pressure composite probe detects the temperature and the pressure of a measured medium, the resolving unit demodulates, compensates the temperature and corrects the output of the pressure sensitive element and the temperature sensitive element in a nonlinear mode respectively to obtain the pressure P and the temperature T, and the pressure P and the temperature T are converted and output in a CAN mode through the output unit. The temperature and pressure composite sensor integrates temperature and pressure signal detection, conversion, conditioning and correction resolving, and realizes higher integration level. The correction method of the temperature measurement part of the sensor can be expanded to a wider temperature range, and the temperature measurement precision of the wide temperature range is improved. The resolving process of the temperature and pressure composite sensor does not need very dense temperature points and pressure points, and the demodulation efficiency is improved.
Description
Technical Field
The invention belongs to the field of airborne sensors, and relates to a temperature and pressure composite sensor and a correction resolving method.
Background
In the field of airplane environmental control systems and the like, temperature and pressure signals are often required to be measured simultaneously. The existing temperature and pressure composite sensor mostly adopts the method of converting pressure and temperature signals into measurable analog electric signals to realize the measurement of temperature and pressure.
For example, in utility model publication No. CN 214251100U, a temperature and pressure integrated sensor is disclosed. The base of the sensor is provided with a thermal probe and a pressure core body, and the temperature is detected through the thermal probe; the pressure detection is realized by converting the pressure core body into a voltage signal through a conversion circuit. The temperature and pressure composite sensor in the form needs to be resolved through a lookup table for a rear-end control system, so that the difficulty of the rear-end system is increased, and the flexible interaction of upper and lower systems is not facilitated.
As disclosed in the utility model with publication number CN 210242865U, the temperature and pressure integrated transmitter adopts the structure that the pressure sensor and the temperature sensor contained in the transmitter are amplified by the pressure amplifying circuit and the temperature amplifying circuit respectively to realize the measurement of pressure and temperature. When the temperature-pressure composite sensor in the form is measured in a temperature range of (-55-125) DEG C, the linearity is poor, and the accuracy of less than 1% is difficult to achieve.
Disclosure of Invention
The invention aims to provide a temperature-pressure composite sensor, which improves the linearity of wide temperature zone measurement, reduces errors and increases the flexibility of interaction with a back-end system.
The technical solution of the invention is as follows:
a temperature and pressure composite sensor comprises a resolving unit, a temperature and pressure composite probe and an output unit; the temperature and pressure composite probe comprises a pressure sensitive element and a temperature sensitive element, the temperature and pressure composite probe detects the temperature and the pressure of a measured medium, the resolving unit demodulates, compensates the temperature and corrects the output of the pressure sensitive element and the temperature sensitive element in a nonlinear mode respectively to obtain the pressure P and the temperature T, and the pressure P and the temperature T are converted and output in a CAN mode through the output unit.
The calculating unit mainly comprises a temperature pre-conditioning module, a pressure pre-conditioning module, a correction calculating module and the like. The temperature pre-conditioning module is mainly used for amplifying the temperature conversion signal, so that the output voltage corresponding to the lower temperature limit and the upper temperature limit of the temperature conversion signal meets the preset requirement.
The pressure pre-conditioning module is mainly used for amplifying the pressure conversion signal to enable the full-scale output voltage to meet a preset value, and adjusting the zero voltage to enable the full-scale output voltage to meet the preset value.
The correction calculation module is used for calculating the temperature according to the preprocessed temperature voltage signal and acquiring, temperature compensating, nonlinear correcting and calculating the preprocessed pressure voltage signal.
The temperature in the calculating unit is calculated by pre-calibrating the relationship between temperature and voltage, and the temperature correction and the nonlinear correction related to the pressure calculation are respectively performed by calibrating the relationship between the pressure and the temperature variation and the relationship between the pressure and the characterization voltage.
The temperature and pressure composite probe is mainly composed of a temperature sensitive element, a pressure sensitive element and a packaging shell. The temperature sensitive element is used for converting the temperature of the measured medium into a measurable resistance signal.
The pressure sensitive element converts the measured medium pressure into a voltage signal under the electric excitation.
The packaging shell provides a transmission channel for measured temperature and pressure signals and has a protection effect on internal temperature sensitive elements and pressure sensitive elements.
And the output unit sends out the resolved temperature and voltage information in a CAN bus form.
A correction calculation method for a temperature-pressure composite sensor comprises the following steps:
(1) obtaining a reference temperature T1Voltage U characterizing the temperature signalt1And a voltage U characterizing the first pressure point P1 at this temperaturep1，t1Voltage U representing second pressure point P2p2，t1Voltage U representing third pressure point P3p3，t1And voltage U representing the pressure at full scalefso,t1。
(2) Obtaining a second temperature point T2Voltage U characterizing the temperature signalt2And a voltage U characterizing the first pressure point at this temperaturep1，t2Voltage U representing the third pressure pointp3，t2And voltage U representing the pressure at full scalefso,t2。
(3) A third temperature point T is obtained3Voltage U characterizing the temperature signalt3And a voltage U characterizing the first pressure point at this temperaturep1，t3Voltage U representing the third pressure pointp3，t3And voltage U representing the pressure at full scalefso,t3。
(4) A fourth temperature point T is obtained4Voltage U characterizing the temperature signalt4。
(5) Obtaining the temperature T and the characterization voltage U according to the parameters measured in the stepstThe relationship between:
T＝f(Ut)
wherein T ∈ { T }1，T2，T3，T4}；Ut∈{Ut1，Ut2，Ut3，Ut4}。
(6) Obtaining a first pressure P1 characterization voltage U according to the parameters measured in the stepsp1，tRelationship with temperature T:
Up1，t＝fp1(T)
wherein, Up1，t∈{Up1，t1，Up1，t2，Up1，t3}；T∈{T1，T2，T3}。
(7) Obtaining full-scale representation voltage U according to the parameters measured in the stepsfsoRelationship with temperature T:
Ufso，t＝ffso(T)
wherein, Ufso，t∈{(Up3，t1-Up1，t1)，(Up3，t2-Up1，t2)，(Up3，t3-Up1，t3)}；
T∈{T1，T2，T3}。
(8) Establishing a temperature compensation model:
Vi＝mt*Up，t+nt
wherein Vi is the ideal voltage value of the pressure after temperature compensation, Up，tCharacterization of the voltage value, m, for pressuretIs the first order coefficient of the temperature compensation model, ntIs Up，tIs an ideal voltage value at 0, and mt、ntAre all temperature dependent.
(9) Establishing non-linearitiesAnd (3) correcting the model: p ═ f (V)i)。
Wherein P is { P1, P1, P3}
Vi∈{V1，V2,V3},V1，V2,V3The temperature compensation voltage values of the pressures P1, P1 and P3 are respectively.
(10) And the temperature T and the pressure P with small errors are obtained through calculation of the model and are output through an output unit.
The invention has the advantages that: the temperature and pressure composite sensor has the functions of temperature compensation and nonlinear correction, the output precision of the sensor CAN be further improved, the precision CAN be improved to 0.5% when the temperature range is measured at (-55-125) DEG C, the output of the temperature and pressure composite sensor adopts a CAN bus form, a plurality of sensors CAN be simultaneously mounted, the problems of complex wiring of a plurality of traditional analog output sensors and mutual interference among wire harnesses are avoided, and the reliability and the flexibility of system interaction are improved.
The temperature and pressure composite sensor integrates temperature and pressure signal detection, conversion, conditioning and correction resolving, and realizes higher integration level. The correction method of the temperature measurement part of the sensor can be expanded to a wider temperature range, and the temperature measurement precision of the wide temperature range is improved. The resolving process of the temperature and pressure composite sensor does not need very dense temperature points and pressure points, and the demodulation efficiency is improved.
Drawings
Fig. 1 is a schematic view showing the composition of a thermo-compression composite sensor according to the present invention.
Detailed Description
The invention provides a temperature and pressure composite sensor and a correction resolving method, which are characterized in that the temperature and nonlinear correction functions are added on the basis of the traditional demodulation mode, and then the corrected temperature and pressure are output through a CAN bus.
The temperature and pressure sensor comprises a calculation unit, a temperature and pressure composite probe and an output unit. The temperature and pressure probe is used for realizing the conversion of the measured medium temperature and pressure signals to the resistance signal RT、RPThe conversion of (1). Pair of solution units RT、RPConditioned and amplified to a temperature dependent voltage signal URFirst electricity related to pressureA voltage signal U1. And further, the voltage signal is acquired, temperature compensation and nonlinear correction are carried out according to a correction formula obtained by calibration in advance, and then the voltage signal is sent to an output unit to output a pressure signal and a temperature signal in a CAN format.
The calculating unit mainly comprises a temperature pre-conditioning module, a pressure pre-conditioning module, a correction calculating module and the like.
The temperature pre-conditioning module applies excitation to the temperature resistance signal for conversion and amplifies the temperature resistance signal by a preset gain to obtain a temperature voltage signal UR。
The pressure preconditioning module applies excitation to the pressure resistance signal to convert the pressure resistance signal to obtain a voltage signal, and amplifies the voltage signal to obtain a pressure representation voltage value UP。
The correction resolving module obtains temperature and voltage U according to pre-calibrationRThe temperature is calculated by the following equation.
The correction calculation module obtains a full-scale temperature compensation ideal voltage value V according to a relationship between the temperature and the full-scale voltage obtained by pre-calibrationfsoObtaining the ideal voltage value V of the zero temperature compensation according to the relation between the temperature and the zero voltage obtained by calibration in advanceoffThen according to the pressure under the reference temperature and the full-range voltage Ufso,t1Zero voltage Up1，t1Voltage U at intermediate pressurep2，t1The relationship between them is compensated for non-linearity.
Wherein the correction solving steps are as follows:
(1) the temperature points needed by temperature signal correction and pressure signal correction are determined, and are usually selected within the working temperature range of the sensor according to the temperature points needed by the compensation model, and the more the temperature points are usually selected, the more accurate the temperature compensation model is, but the more complex the calculation process is. In this embodiment, four temperature points T are selected1、T2、T3、T4. Wherein T is1～T3For correction of pressure signals, T1～T4For temperature signal correction. For convenience of operation, T1The temperature is 20 ℃ at room temperature, T2 is-55 ℃ at the lower limit of the working temperature range, and T3 is HThe lower end of the temperature range was 125 ℃ and T4 was 70 ℃.
(2) Determining the number of pressure points needed by pressure correction, wherein the selection of the pressure points for temperature compensation needs to compensate the zero point and the sensitivity, i.e. 2 pressure points, and in order to improve the accuracy of the non-linear correction, three pressure points P are selected in the embodiment1，P2，P3Wherein P1 is the pressure at the middle point of the measured pressure range of 1MPa, P2Zero point pressure was 0 MPa. P3The full point pressure was 2 MPa.
(3) Measuring the amplified voltage U of the temperature sensitive element at 20 deg.Ct1Respectively measuring the pressure-sensitive elements after amplification at P1、P2、P3Output voltage U under pressurep1，t1、Up2，t1、Up3，t1. And calculating the full-scale voltage U at 20 DEG Cfso,t1。
(4) Measuring the amplified voltage U of the temperature sensitive element at-55 deg.Ct2Respectively measuring the voltage U of the pressure sensitive element amplified under the pressure of P1p1，t2Amplified voltage U at P3 pressurep3，t2。And calculating the full-scale voltage U at-55 DEG Cfso,t2。
(5) Measuring the amplified voltage U of the temperature sensitive element at 125 deg.Ct3Respectively measuring the voltage U of the pressure sensitive element amplified under the pressure of P1p1，t3Amplified voltage U at P3 pressurep3，t3。And calculating the full-scale voltage U at 125 DEG Cfso,t3。
(6) Measuring the amplified voltage U of the temperature sensitive element at 70 deg.Ct4。
(7) According to the measured Ut1、Ut2、Ut3、Ut4The value of (A) is calculated to obtain the temperature T and the characterization voltage UtThe relationship between:
T＝k3*Ut 3+k2*Ut 2+k1*Ut+t0
wherein k is3Is a nonlinear third-order coefficient, k2Is a non-linear second-order coefficient,k1is a nonlinear first-order coefficient, t0Is UtThe temperature represented by 0V.
(8) Calculating to obtain zero-point pressure characterization voltage U according to the measured valuesp1Relationship with temperature T:
Up1，t＝f2*T2+f1*T+up1，0
wherein f is2Is a second order temperature coefficient, f1Is a first order temperature coefficient, up1，0The characteristic voltage of zero point at 0 ℃ is shown.
(9) Calculating to obtain a full-scale pressure characterization voltage U according to the measured valuesfsoRelationship with temperature T:
Ufso，t＝y2*T2+y1*T+ufso，0
wherein, y2Is a second order temperature coefficient, y1Is a first order temperature coefficient, ufso，0Is characterized by the full scale of voltage at 0 ℃.
(10) According to a temperature compensation model established in advance: vi ═ mt*Up，t+nt
(11) Formula and V combining (8) and (9)off，VfsoSubstituting (10) to calculate mt,nt；
(12) Based on U in (10) and (3)p1，t1、Up2，t1、Up3，t1Calculating a nonlinear correction coefficient alpha of pressure1、α2And obtaining a nonlinear correction relation:
P＝α2*Vi 2+α1*Vi+v0
wherein alpha is2Is a second-order nonlinear correction coefficient, alpha1Is a nonlinear correction coefficient, v0Is a pressure at which the ideal voltage is 0.
(13) The temperature and pressure signals are solved according to the solving relational expressions (7) and (12).
Claims (9)
1. The temperature and pressure composite sensor is characterized by comprising a resolving unit, a temperature and pressure composite probe and an output unit; the temperature and pressure composite probe comprises a pressure sensitive element and a temperature sensitive element, the temperature and pressure composite probe detects the temperature and the pressure of a measured medium, the resolving unit demodulates, compensates the temperature and corrects the output of the pressure sensitive element and the temperature sensitive element in a nonlinear mode respectively to obtain the pressure P and the temperature T, and the pressure P and the temperature T are converted and output in a CAN mode through the output unit.
2. The temperature-pressure composite sensor according to claim 1, wherein the calculating unit mainly comprises a temperature pre-conditioning module, a pressure pre-conditioning module and a correction calculating module; the temperature pre-conditioning module is mainly used for amplifying the temperature conversion signal, so that the output voltage corresponding to the lower temperature limit and the upper temperature limit of the temperature conversion signal meets the preset requirement.
3. The sensor of claim 1, wherein the pressure preconditioning module amplifies the pressure-converted signal to make its full-scale output voltage meet a predetermined value, and adjusts its null voltage to make it meet the predetermined value.
4. The temperature-pressure composite sensor according to claim 1, wherein the correction calculation module performs temperature calculation according to the preprocessed temperature voltage signal, and performs acquisition, temperature compensation, nonlinear correction and calculation on the preprocessed pressure voltage signal.
5. The temperature-pressure composite sensor according to claim 1, wherein the temperature calculation in the calculation unit is performed by calibrating the relationship between temperature and voltage in advance, and the temperature correction and the nonlinear correction related to the pressure calculation are performed by calibrating the relationship between the pressure and the temperature variation and the relationship between the pressure and the characterization voltage respectively.
6. The composite sensor of claim 1, wherein the composite probe is mainly composed of a temperature sensitive element, a pressure sensitive element and a packaging shell; the temperature sensitive element is used for converting the temperature of the measured medium into a measurable resistance signal.
7. The composite sensor of claim 1, wherein the pressure sensitive element converts the measured pressure of the medium into a voltage signal under electrical excitation.
8. The temperature-pressure composite sensor according to claim 1, wherein the output unit sends the calculated temperature and voltage information in the form of a CAN bus.
9. A correction calculation method for a temperature-pressure composite sensor is characterized by comprising the following steps:
(1) obtaining a reference temperature T1Voltage U characterizing the temperature signalt1And a voltage U characterizing the first pressure point P1 at this temperaturep1，t1Voltage U representing second pressure point P2p2，t1Voltage U representing third pressure point P3p3，t1And voltage U representing the pressure at full scalefso,t1；
(2) Obtaining a second temperature point T2Voltage U characterizing the temperature signalt2And a voltage U characterizing the first pressure point at this temperaturep1，t2Voltage U representing the third pressure pointp3，t2And voltage U representing the pressure at full scalefso,t2；
(3) A third temperature point T is obtained3Voltage U characterizing the temperature signalt3And a voltage U characterizing the first pressure point at this temperaturep1，t3Voltage U representing the third pressure pointp3，t3And voltage U representing the pressure at full scalefso,t3；
(4) A fourth temperature point T is obtained4Voltage U characterizing the temperature signalt4；
(5) Obtaining the temperature T and the characterization voltage U according to the parameters measured in the stepstThe relationship between:
T＝f(Ut)
wherein T ∈ { T }1，T2，T3，T4}；Ut∈{Ut1，Ut2，Ut3，Ut4}；
(6) Obtaining a first pressure P1 characterization voltage U according to the parameters measured in the stepsp1，tRelationship with temperature T:
Up1，t＝fp1(T)
wherein, Up1，t∈{Up1，t1，Up1，t2，Up1，t3}；T∈{T1，T2，T3}；
(7) Obtaining full-scale representation voltage U according to the parameters measured in the stepsfsoRelationship with temperature T:
Ufso，t＝ffso(T)
wherein, Ufso，t∈{(Up3，t1-Up1，t1)，(Up3，t2-Up1，t2)，(Up3，t3-Up1，t3)}；
T∈{T1，T2，T3}；
(8) Establishing a temperature compensation model:
Vi＝mt*Up，t+nt
wherein Vi is the ideal voltage value of the pressure after temperature compensation, Up，tCharacterization of the voltage value, m, for pressuretIs the first order coefficient of the temperature compensation model, ntIs Up，tIs an ideal voltage value at 0, and mt、ntAre all temperature dependent;
(9) establishing a nonlinear correction model: p ═ f (V)i)；
Wherein P is { P1, P1, P3}
Vi∈{V1，V2,V3},V1，V2,V3Temperature compensation voltage values of the pressures P1, P1 and P3 respectively;
(10) and the temperature T and the pressure P with small errors are obtained through calculation of the model and are output through an output unit.
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| CN114544042A (en) * | 2022-04-27 | 2022-05-27 | 成都凯天电子股份有限公司 | Pressure error compensation method for vibrating cylinder pressure sensor under variable temperature condition |
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| CN114544042A (en) * | 2022-04-27 | 2022-05-27 | 成都凯天电子股份有限公司 | Pressure error compensation method for vibrating cylinder pressure sensor under variable temperature condition |
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