A temperature and pressure composite sensor and correction solution method

Abstract

The present invention belongs to the field of airborne sensors, and relates to a temperature-pressure composite sensor and a correction and solution method. The temperature-pressure composite probe includes a pressure sensitive element and a temperature sensitive element. The temperature-pressure composite probe detects the temperature and pressure of the measured medium. The solution unit demodulates, temperature compensates, and performs nonlinear correction on the outputs of the pressure sensitive element and the temperature sensitive element, respectively, to obtain the pressure P and the temperature T, and converts the output in the form of CAN through the output unit. The temperature-pressure composite sensor integrates temperature and pressure signal detection, conversion, conditioning, correction and solution, achieving a higher degree of integration. The correction method of the temperature measurement part of the sensor can be extended to a wider temperature range, thereby improving the temperature measurement accuracy in a wide temperature range. The solution process of the temperature-pressure composite sensor does not require very dense temperature points and pressure points, thereby improving the efficiency of demodulation.

Description

Technical Field

[0001] The invention belongs to the field of airborne sensors and relates to a temperature-pressure composite sensor and a correction solution method. Background Art

[0002] In the field of aircraft environmental control systems, it is often necessary to measure temperature and pressure signals simultaneously. Existing temperature and pressure composite sensors mostly convert pressure and temperature signals into measurable analog electrical signals to achieve temperature and pressure measurement.

[0003] For example, in the utility model with publication number CN 214251100U, a temperature-pressure integrated sensor is disclosed. The base of the sensor is provided with a thermal probe and a pressure core, and the temperature is detected by the thermal probe; the pressure is detected by converting the pressure core into a voltage signal through a conversion circuit. This type of temperature-pressure composite sensor needs to be solved by a lookup table for the back-end control system, which increases the difficulty of the back-end system and is not conducive to the flexible interaction between the upper and lower systems.

[0004] Another example is the integrated temperature and pressure transmitter disclosed in the utility model with publication number CN 210242865U, which uses a pressure sensor and a temperature sensor contained in the transmitter to measure pressure and temperature after being amplified by a pressure amplifier circuit and a temperature amplifier circuit respectively. This type of temperature and pressure composite sensor has poor linearity when measuring in the temperature range of (-55 to 125)°C, and it is difficult to achieve an accuracy of less than 1%. Summary of the invention

[0005] The purpose of the present invention is to provide a temperature-pressure composite sensor to improve the linearity of wide temperature range measurement, reduce errors, and increase the flexibility of interaction with a back-end system.

[0006] The technical solution of the present invention:

[0007] A temperature-pressure composite sensor comprises a solution unit, a temperature-pressure composite probe and an output unit; the temperature-pressure composite probe comprises a pressure sensitive element and a temperature sensitive element, the temperature-pressure composite probe detects the temperature and pressure of a measured medium, the solution unit respectively demodulates, temperature compensates and performs nonlinear correction on the outputs of the pressure sensitive element and the temperature sensitive element to obtain pressure P and temperature T, and converts and outputs them in the form of CAN through the output unit.

[0008] The solution unit mainly includes a temperature pre-conditioning module, a pressure pre-conditioning module, a correction solution module, etc. The temperature pre-conditioning module mainly amplifies the temperature conversion signal so that the output voltage corresponding to the lower temperature limit and the upper temperature limit meets the preset requirements.

[0009] The pressure preconditioning module mainly amplifies the pressure conversion signal so that its full-scale output voltage meets the preset value, and adjusts its zero-position voltage so that it meets the preset value.

[0010] The correction and solution module solves the temperature according to the preprocessed temperature and voltage signals, and at the same time collects, temperature compensates, performs nonlinear correction and solves the preprocessed pressure and voltage signals.

[0011] The temperature solution in the solution unit is performed by pre-calibrating the relationship between temperature and voltage. The temperature correction and nonlinear correction involved in the pressure solution are performed by calibrating the relationship between pressure and temperature and the relationship between pressure and characterization voltage, respectively.

[0012] The temperature-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 to convert the temperature of the measured medium into a measurable resistance signal.

[0013] The pressure sensitive element converts the measured medium pressure into a voltage signal under electrical excitation.

[0014] The packaging shell provides a transmission channel for the measured temperature and pressure signals, and protects the internal temperature sensitive components and pressure sensitive components.

[0015] The output unit sends the calculated temperature and voltage information in the form of a CAN bus.

[0016] A correction and solution method for a temperature-pressure composite sensor comprises the following steps:

[0017] (1) Obtain the voltage U representing the temperature signal at the reference temperature T1 t1 , and the voltage U representing the first pressure point P1 at this temperature p1，t1 , representing the voltage U of the second pressure point P2 p2，t1 , representing the voltage U of the third pressure point P3 p3，t1 And the voltage U representing the full-scale pressure fso,t1 .

[0018] (2) Obtain the voltage U representing the temperature signal at the second temperature point T2 t2 , and the voltage U that characterizes the first pressure point at this temperature p1，t2 , representing the voltage U of the third pressure point p3，t2 And the voltage U representing the full-scale pressure fso,t2 .

[0019] (3) Obtain the voltage U representing the temperature signal at the third temperature point T3 t3 , and the voltage U that characterizes the first pressure point at this temperature p1，t3 , representing the voltage U of the third pressure pointp3，t3 And the voltage U representing the full-scale pressure fso,t3 .

[0020] (4) Obtain the voltage U representing the temperature signal at the fourth temperature point T4 t4 .

[0021] (5) According to the parameters measured in the above steps, the temperature T and the characterization voltage U are obtained. t The relationship between:

[0022] T=f(U t )

[0023] Among them, T∈{T1, T2, T3, T4}; U t ∈{U t1 , U t2 , U t3 , U t4}.

[0024] (6) Obtain the first pressure P1 characteristic voltage U according to the parameters measured in the above steps p1，t The relationship with temperature T:

[0025] U p1，t =f p1 (T)

[0026] Among them, U p1，t ∈{U p1，t1 , U p1，t2 , U p1，t3}; T∈{T1, T2, T3}.

[0027] (7) According to the parameters measured in the above steps, the full-scale characterization voltage U is obtained fso The relationship with temperature T:

[0028] U fso，t =f fso (T)

[0029] Among them, U fso，t ∈{(U p3，t1 -U p1，t1 ), (U p3，t2 -U p1，t2 ), (U p3，t3 -U p1，t3 )};

[0030] T∈{T1, T2, T3}.

[0031] (8) Establish a temperature compensation model:

[0032] Vi=m t *U p，t +n t

[0033] Among them, Vi is the ideal pressure voltage value after temperature compensation, U p，t is the pressure characterization voltage value, m t is the first-order coefficient of the temperature compensation model, n t It's U p，t The ideal voltage value when m is 0, and t 、n t Are all related to temperature.

[0034] (9) Establish a nonlinear correction model: P = f(V i ).

[0035] Where P∈{P1,P1,P3}

[0036] V i ∈{V1,V2,V3}, V1,V2,V3 are the temperature compensation voltage values ​​of pressures P1,P1,P3 respectively.

[0037] (10) The temperature T and pressure P with smaller errors are obtained by solving the above model and output through the output unit.

[0038] Advantages of the present invention: The temperature-pressure composite sensor has both temperature compensation and nonlinear correction functions, which can further improve the output accuracy of the sensor. When measuring in the temperature range of (-55 to 125)°C, the accuracy can be improved to 0.5%. Its output adopts the form of CAN bus, and multiple sensors can be mounted at the same time to avoid the complex wiring problems of traditional multiple analog output sensors and the mutual interference problems between wiring harnesses, thereby increasing reliability and flexibility in interacting with the system.

[0039] The temperature-pressure composite sensor integrates temperature and pressure signal detection, conversion, conditioning, correction and solution, achieving a higher level of integration. The correction method of the temperature measurement part of the sensor can be extended to a wider temperature range, improving the temperature measurement accuracy in a wide temperature range. The solution process of the temperature-pressure composite sensor does not require very dense temperature points and pressure points, which improves the efficiency of demodulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram showing the composition of the temperature-pressure composite sensor of the present invention. DETAILED DESCRIPTION

[0041] The present invention provides a temperature-pressure composite sensor and a correction and solution method, which adds temperature and nonlinear correction functions on the basis of a traditional demodulation method, and then outputs the corrected temperature and pressure through a CAN bus.

[0042] The temperature and pressure sensor comprises a solution unit, a temperature and pressure composite probe and an output unit. The temperature and pressure probe is used to convert the measured medium temperature and pressure signals into a resistance signal RT , R P The solution unit is R T , R P Conditioning and amplification into a temperature-dependent voltage signal U R , a first voltage signal U1 related to pressure. Further, the voltage signal is collected and subjected to temperature compensation and nonlinear correction according to a pre-calibrated correction formula, and then sent to the output unit to output pressure and temperature signals in CAN format.

[0043] The solution unit mainly includes a temperature pre-conditioning module, a pressure pre-conditioning module, a correction solution module, etc.

[0044] The temperature preconditioning module applies excitation to the temperature resistance signal for conversion and amplifies it with a preset gain to obtain a temperature voltage signal U R .

[0045] The pressure preconditioning module applies excitation to the pressure resistance signal to convert it into a voltage signal, and then amplifies it to obtain the pressure representation voltage value U P .

[0046] The correction calculation module is based on the pre-calibrated temperature and voltage U R The temperature is calculated using the relationship.

[0047] The correction calculation module obtains the ideal voltage value V of full-scale temperature compensation according to the pre-calibrated temperature and full-scale voltage relationship. fso According to the relationship between temperature and zero voltage obtained in advance, the ideal voltage value V of zero temperature compensation is obtained. off , and then according to the pressure at the reference temperature, the full-scale voltage U fso,t1 , zero voltage U p1，t1 , Voltage U at intermediate pressure p2 , t1 The nonlinear relationship between them is compensated.

[0048] The correction solution steps are as follows:

[0049] (1) Determine the temperature points required for temperature signal correction and pressure signal correction. Usually, the temperature points are selected within the operating temperature range of the sensor according to the number of temperature points required by the compensation model. Generally, the more temperature points are selected, the more accurate the temperature compensation model is, but the more complicated the calculation process is. In this embodiment, four temperature points T1, T2, T3, and T4 are selected. Among them, T1 to T3 are used for pressure signal correction, and T1 to T4 are used for temperature signal correction. For ease of operation, T1 is selected as room temperature 20°C, T2 is selected as the lower limit of the operating temperature range -55°C, T3 is selected as the lower limit of the operating temperature range 125°C, and T4 is 70°C.

[0050] (2) Determine the number of pressure points required for pressure calibration. The pressure point selection for temperature compensation needs to be able to compensate for the zero point and sensitivity, that is, two pressure points are sufficient. In order to improve the accuracy of nonlinear correction, three pressure points P1, P2, and P3 are selected in this embodiment, where P1 is the middle point pressure of the measured pressure range 1MPa, P2 is the zero point pressure 0MPa, and P3 is the full point pressure 2MPa.

[0051] (3) Measure the amplified voltage U of the temperature sensitive element at 20°C t1 , respectively measure the output voltage U of the pressure sensitive element after amplification at pressures P1, P2, and P3 p1，t1 , U p2，t1 , U p3，t1 . And calculate the full-scale voltage U at 20°C fso,t1 .

[0052] (4) Measure the amplified voltage U of the temperature sensitive element at -55°C t2 , respectively measure the amplified voltage U of the pressure sensitive element under the pressure of P1 p1，t2 , the amplified voltage U under P3 pressure p3，t2。 And calculate the full-scale voltage U at -55℃ fso,t2 .

[0053] (5) Measure the amplified voltage U of the temperature sensitive element at 125°C t3 , respectively measure the amplified voltage U of the pressure sensitive element under the pressure of P1 p1，t3 , the amplified voltage U under P3 pressure p3，t3。 And calculate the full-scale voltage U at 125°C fso,t3 .

[0054] (6) Measure the amplified voltage U of the temperature sensitive element at 70°C t4 .

[0055] (7) According to the above measured U t1 , U t2 , U t3 , U t4 The calculated value of temperature T and characterization voltage U t The relationship between:

[0056] T=k3*U t 3 +k2*U t 2 +k1*U t +t0

[0057] Among them, k3 is the nonlinear third-order coefficient, k2 is the nonlinear second-order coefficient, k1 is the nonlinear first-order coefficient, and t0 is U tThe temperature represented by 0V.

[0058] (8) Calculate the zero-point pressure characterization voltage U based on the above measured values p1 The relationship with temperature T:

[0059] U p1，t =f2*T 2 +f1*T+u p1，0

[0060] Among them, f2 is the second-order temperature coefficient, f1 is the first-order temperature coefficient, and u p1，0 It is the voltage representing the zero point at 0℃.

[0061] (9) The full-scale pressure characterization voltage U is calculated based on the above measured values. fso The relationship with temperature T:

[0062] U fso，t =y2*T 2 +y1*T+u fso，0

[0063] Among them, y2 is the second-order temperature coefficient, y1 is the first-order temperature coefficient, and u fso，0 It is the full-scale characterization voltage at 0°C.

[0064] (10) According to the temperature compensation model established in advance: Vi = m t *U p，t +n t

[0065] (11) Combining the formulas (8) and (9) with V off , V fso Substitute into (10) and calculate m t ,n t ;

[0066] (12) Based on U in (10) and (3) p1，t1 , U p2，t1 , U p3，t1 , calculate the nonlinear correction coefficients α1 and α2 of pressure, and obtain the nonlinear correction relationship:

[0067] P=α2*V i 2 +α1*V i +v0

[0068] Among them, α2 is the second-order nonlinear correction coefficient, α1 is the nonlinear correction coefficient, and v0 is the pressure when the ideal voltage is 0.

[0069] (13) The temperature and pressure signals are calculated based on the above-mentioned equations (7) and (12).

Claims

1. A temperature and pressure composite sensor, characterized in that: It includes a solution unit, a temperature-pressure composite probe and an output unit; the temperature-pressure composite probe includes a pressure sensitive element and a temperature sensitive element, and the temperature-pressure composite probe detects the temperature and pressure of the measured medium; the solution unit demodulates, temperature compensates, and performs nonlinear correction on the outputs of the pressure sensitive element and the temperature sensitive element, respectively, to obtain the pressure P and the temperature T, and converts the output in the form of CAN through the output unit; when correcting and solving, it includes the following steps: (1) Obtain the voltage U representing the temperature signal at the reference temperature T1 t1 , and the voltage U representing the first pressure point P1 at this temperature p1，t1 , representing the voltage U of the second pressure point P2 p2，t1 , representing the voltage U of the third pressure point P3 p3，t1 And the voltage U representing the full-scale pressure fso,t1 ; (2) Obtain the voltage U representing the temperature signal at the second temperature point T2 t2 , and the voltage U that characterizes the first pressure point at this temperature p1，t2 , representing the voltage U of the third pressure point p3，t2 And the voltage U representing the full-scale pressure fso,t2 ; (3) Obtain the voltage U representing the temperature signal at the third temperature point T3 t3 , and the voltage U that characterizes the first pressure point at this temperature p1，t3 , representing the voltage U of the third pressure point p3，t3 And the voltage U representing the full-scale pressure fso,t3 ; (4) Obtain the voltage U representing the temperature signal at the fourth temperature point T4 t4 ; (5) According to the parameters measured in the above steps, the temperature T and the characterization voltage U are obtained. t The relationship between: T=f(U t ) Among them, T∈{T1, T2, T3, T4}; U t ∈{U t1 , U t2 , U t3 , U t4 }; T=k3*U t 3 +k2*U t 2 +k1*U t +t0 Among them, k3 is the nonlinear third-order coefficient, k2 is the nonlinear second-order coefficient, k1 is the nonlinear first-order coefficient, and t0 is U t The temperature represented by 0V; (6) Obtain the first pressure P1 characteristic voltage U according to the parameters measured in the above steps p1，t The relationship with temperature T: U p1，t =f p1 (T) Among them, U p1，t ∈{U p1，t1 , U p1，t2 , U p1，t3 }; T∈{T1, T2, T3}; U p1，t =f2*T 2 +f1*T+u p1，0 Among them, f2 is the second-order temperature coefficient, f1 is the first-order temperature coefficient, and u p1，0 It is the voltage representing the zero point at 0°C; (7) According to the parameters measured in the above steps, the full-scale characterization voltage U is obtained fso The relationship with temperature T: U fso，t =f fso (T) Among them,U fso，t ∈{(U p3，t1 -IN p1，t1 ),(IN p3，t2 -IN p1，t2 ),(IN p3，t3 -IN p1，t3 )}; T∈{T1,T2,T3}; U fso，t =y2*T 2 +y1*T+u fso，0 Among them, y2 is the second-order temperature coefficient, y1 is the first-order temperature coefficient, and u fso，0 It is the characterization voltage of full scale at 0℃; (8) Establish a temperature compensation model: You=m t *IN p，t +n t Among them, Vi is the ideal pressure voltage value after temperature compensation, U p，t is the pressure characterization voltage value, m t is the first-order coefficient of the temperature compensation model, n t It's U p，t The ideal voltage value when m is 0, and t 、n t All are related to temperature; (9) Establish a nonlinear correction model: P = f(V i ); Where P∈{P1,P1,P3} V i ∈{V1, V2, V3}, V1, V2, V3 are the temperature compensation voltage values ​​of pressures P1, P1, P3 respectively; P=α2*V i 2 +α1*V i +v0 Among them, α2 is the second-order nonlinear correction coefficient, α1 is the nonlinear correction coefficient, and v0 is the pressure when the ideal voltage is 0; (10) The temperature T and pressure P with smaller errors are obtained by solving the above model and output through the output unit.

2. A temperature and pressure composite sensor according to claim 1, characterized in that: The solution unit mainly includes a temperature pre-conditioning module, a pressure pre-conditioning module, and a correction solution module; the temperature pre-conditioning module mainly amplifies the temperature conversion signal so that the output voltage corresponding to the lower temperature limit and the upper temperature limit meets the preset requirements.

3. A temperature and pressure composite sensor according to claim 1, characterized in that: The pressure preconditioning module mainly amplifies the pressure conversion signal so that its full-scale output voltage meets the preset value, and adjusts its zero-position voltage so that it meets the preset value.

4. A temperature and pressure composite sensor according to claim 1, characterized in that: The correction and solution module solves the temperature according to the preprocessed temperature and voltage signals, and at the same time collects, temperature compensates, performs nonlinear correction and solves the preprocessed pressure and voltage signals.

5. The temperature-pressure composite sensor according to claim 1, characterized in that: The temperature solution in the solution unit is performed by pre-calibrating the relationship between temperature and voltage. The temperature correction and nonlinear correction involved in the pressure solution are performed by calibrating the relationship between pressure and temperature and the relationship between pressure and characterization voltage, respectively.

6. A temperature and pressure composite sensor according to claim 1, characterized in that: The temperature-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 to convert the temperature of the measured medium into a measurable resistance signal.

7. The temperature-pressure composite sensor according to claim 1, characterized in that: The pressure sensitive element converts the measured medium pressure into a voltage signal under electrical excitation.

8. The temperature-pressure composite sensor according to claim 1, characterized in that: The output unit sends the calculated temperature and voltage information in the form of a CAN bus.

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