A multi-source pressure sensor range calibration method

Abstract

The present application relates to the technical field of sensor, in particular to a kind of multi-source pressure sensor range calibration method, measurement is carried out using multi-source pressure sensor, at least two range of sensitive structure are included in multi-source pressure sensor and each sensitive structure is connected with its corresponding detection circuit, user selects a kind of sensitive structure to measure according to required range, the process of calibration of the measured value of sensitive structure includes: setting temperature calibration point and pressure calibration point, and the normalized voltage value of temperature sensor's temperature-sensitive resistance output in current circuit is obtained according to calibration point, the normalized voltage value of pressure-sensitive bridge output and the equation obtained by fitting of voltage calibration point;The normalized voltage value of temperature-sensitive resistance output measured and the normalized voltage value of pressure-sensitive bridge output are input into the equation obtained by fitting, and the calibrated pressure value is output.The present application can match corresponding sensitive structure according to actual pressure detection range, and reduce the influence of environmental factors.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a multi-source pressure sensor range calibration method. BACKGROUND

[0002] Vacuum refers to a state of gas lower than one standard atmosphere, and the measurement of vacuum degree is widely applied in industrial equipment instruments such as semiconductor manufacturing, advanced material processing, aerospace, nuclear power generation, energy transportation, etc. At present, different detection technologies have their own advantages and disadvantages in different vacuum degrees, so using appropriate sensitive structure for detection of different vacuum degree range can greatly reduce the influence of many factors such as temperature, humidity and power fluctuation, so as to improve the stability and detection accuracy of the sensor.

[0003] Among many environmental factors, the change of temperature has the greatest influence on the sensor. The common temperature compensation method at present is direct temperature compensation, that is, through a constant current source to supply power to a temperature sensitive resistor, and collect voltage data at multiple points for voltage fitting temperature. However, in actual detection, the constant current source may fluctuate with the change of temperature, and in the obtained second-order voltage fitting formula, the coefficients of the polynomial are very large. When the output voltage of the temperature sensitive resistor fluctuates for some reason, it will seriously affect the actual temperature obtained by fitting, and a large error will occur, which will seriously affect the stability and detection accuracy of the sensor. SUMMARY

[0004] In order to solve the problem of the influence of temperature change on the precision of pressure sensor and realize multi-range or full-range high-precision pressure detection, the present application provides a multi-source pressure sensor range calibration method. The multi-source pressure sensor is used for measurement, and at least two range sensitive structures are included in the multi-source pressure sensor, and each sensitive structure is connected with its corresponding detection circuit. The user selects a sensitive structure for measurement according to the required range, and the calibration process of the measurement value of the sensitive structure includes the following steps:

[0005] Setting temperature calibration points and pressure calibration points, and obtaining the normalized voltage value of the temperature sensor's temperature sensitive resistor output, the normalized voltage value of the pressure sensitive bridge output and the equation obtained by fitting the voltage calibration points in the current circuit according to the calibration points;

[0006] Inputting the normalized voltage value of the temperature sensitive resistor output and the normalized voltage value of the pressure sensitive bridge output obtained by measurement into the equation obtained by fitting, and outputting the calibrated pressure value.

[0007] Further, the process of obtaining the normalized voltage value of the temperature sensor's temperature sensitive resistor output, the normalized voltage value of the pressure sensitive bridge output and the equation obtained by fitting the voltage calibration points in the current circuit according to the calibration points includes:

[0008] Applying a pressure calibration point to the sensitive structure, obtaining the actual measurement value of the sensitive structure at the pressure calibration point, using the pressure calibration point as the output and the measurement value as the input to perform fitting by using a first-order equation;

[0009] Using the slope and zero point of the first-order equation obtained by fitting at each temperature calibration point, performing quadratic fitting to obtain a quadratic equation of temperature and the slope and zero point of the first-order equation;

[0010] According to the normalized voltage value of the temperature-sensitive resistor output, the current temperature is calculated, the current temperature is input into the quadratic equation of the slope and zero point to obtain the corresponding slope and zero point, and a first-order equation is established according to the obtained slope and zero point;

[0011] The measurement value obtained according to the current sensitive structure is input into the established first-order equation to obtain the calibrated pressure value.

[0012] Further, the current temperature value is obtained by a current calibration method.

[0013] Further, the process of obtaining the current temperature value by the current calibration method includes:

[0014] According to the resistance-temperature relationship table provided by the temperature-sensitive resistor, the resistance value of the temperature-sensitive resistor at different temperatures is obtained.

[0015] The output voltage of the temperature-sensitive resistor at the measured temperature is measured, and the current is calculated by dividing the voltage by the resistance to obtain a fitting curve of the current and the voltage at different temperatures.

[0016] The output voltage of the measured temperature-sensitive resistor is substituted into the fitting curve to obtain the related current, the resistance is obtained by dividing the voltage by the current, and the current actual temperature is obtained by the relationship between the resistance value of the temperature-sensitive resistor and the temperature.

[0017] Further, the process of obtaining the normalized voltage value of the temperature-sensitive resistor output of the temperature sensor in the current circuit and the normalized voltage value of the pressure-sensitive bridge output according to the calibration point and the fitting equation of the voltage calibration point includes: directly fitting the normalized voltage value of the temperature-sensitive resistor output as the x-axis, the normalized voltage value of the pressure-sensitive bridge output as the y-axis, and the voltage calibration point as the z-axis.

[0018] Further, the sensitive structure includes a piezoresistive pressure sensor, a piezoelectric pressure sensor, and a resonant pressure sensor.

[0019] Further, in the multi-source pressure sensor, one sensitive structure is in an always-on state and the other sensitive structures are in an always-off state, and the measurement value of the always-on state sensitive structure is used for judgment, if the measurement value of the always-on state sensitive structure exceeds its measurement range, the always-on state sensitive structure is closed, and the corresponding range sensitive structure is opened.

[0020] The present invention can match the corresponding sensitive structure according to the actual pressure detection range to reduce the influence of environmental factors, and at the same time use the current calibration method to obtain a more accurate actual temperature to achieve high-stability and high-precision measurement of the pressure within the corresponding range. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of a pressure sensor range calibration method according to an embodiment of the present invention;

[0022] Figure 2 is a fitting curve diagram of the normalized value of the pressure-sensitive bridge voltage and the actual pressure according to an embodiment of the present invention;

[0023] Figure 3 is a fitting curve diagram of the normalized value of the pressure-sensitive bridge voltage and the actual pressure at different temperatures according to an embodiment of the present invention;

[0024] Figure 4 is a fitting curve diagram of the direct temperature compensation method according to an embodiment of the present invention;

[0025] Figure 5 This is a fitting curve diagram of the current calibration temperature compensation method according to an embodiment of the present invention;

[0026] Figure 6 is a fitting curve diagram of the slope of the actual temperature and pressure calibration curve of an embodiment of the present invention;

[0027] Figure 7 A fitting curve diagram of the zero point of the actual temperature and pressure calibration curve of an embodiment of the present invention;

[0028] Figure 8 1 is a fitting curve diagram of the normalized output voltage of the temperature-sensitive resistor, the normalized output voltage of the pressure-sensitive bridge and the actual pressure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] The present invention provides a method for calibrating the range of a multi-source pressure sensor. The multi-source pressure sensor is used for measurement. The multi-source pressure sensor includes at least two sensitive structures with different ranges, and each sensitive structure is connected to its corresponding detection circuit. The user selects a sensitive structure for measurement according to the required range. The process of calibrating the measured value of the sensitive structure includes the following steps:

[0031] The temperature calibration point and the pressure calibration point are set, and a fitting equation of normalized voltage values of temperature sensor resistance output and normalized voltage values of pressure sensing bridge output in the current circuit according to the calibration points is obtained;

[0032] The normalized voltage values of temperature sensor resistance output and normalized voltage values of pressure sensing bridge output in the current circuit are input into the fitting equation, and a calibrated pressure value is output.

[0033] As Figure 1 The process of obtaining the fitting equation of normalized voltage values of temperature sensor resistance output and normalized voltage values of pressure sensing bridge output in the current circuit according to the calibration points comprises:

[0034] The force of the pressure calibration point is applied to the sensitive structure, the actual measurement value of the sensitive structure at the pressure calibration point is obtained, and the pressure calibration point is taken as the output and the measurement value is taken as the input to perform fitting by using the first-order equation;

[0035] The slope and zero point of the first-order equation fitted under each temperature calibration point are used for secondary fitting to obtain a second-order equation of temperature and the slope and zero point of the first-order equation;

[0036] The current temperature is calculated according to the normalized voltage value of the temperature sensor resistance output, the current temperature is input into the second-order equation of the slope and the zero point to obtain the corresponding slope and zero point, and a first-order equation is established according to the obtained slope and zero point;

[0037] The measurement value obtained according to the current sensitive structure is input into the established first-order equation to obtain a calibrated pressure value.

[0038] In one specific embodiment of the present application, a signal calibration method is illustrated by taking a piezoresistive sensitive structure as an example; under the condition that the constant voltage is supplied, the temperature and humidity remain unchanged, the fitting curve of the normalized value of the pressure sensing bridge voltage and the actual pressure is measured as shown in Figure 2 The first-order equation fitted is expressed as y=69.506x+1.0783, wherein x represents the normalized value of the pressure sensing bridge output voltage, and y represents the actual pressure; the horizontal axis in the figure represents the normalized value of the pressure sensing bridge output voltage, and the vertical axis represents the actual pressure, the fitting curve is obtained by first-order polynomial fitting, and it is proved that the relationship between the two is basically linear and can be fitted by a linear function. The first-order calibration equation in this way can have the following form:

[0039] Y=A*X+B

[0040] Wherein, Y is the actual value of the pressure, X is the voltage signal output by the sensitive structure, A is the slope of the calibration curve at different temperatures, and B is the zero point value of the calibration curve at different temperatures.

[0041] The fitting curves of the normalized value of the voltage of the Wheatstone pressure sensing bridge and the actual pressure at different standard temperature values are shown in FIG. 1, where the abscissa is 0.2, and three fitting lines with decreasing actual pressure values are represented as: Figure 3

[0042] Fitting line 1: y = 78.99x + 1.1879, temperature 60℃

[0043] Fitting line 2: y = 64.861x + 1.0063, temperature 0℃

[0044] Fitting line 3: y = 54.188x + 0.8556, temperature -45℃

[0045] As can be seen from the above curves, when the temperature remains unchanged, the output voltage of the Wheatstone pressure sensing bridge and the actual pressure are basically in a linear relationship, and the fitting curve can be obtained by a first-order function; meanwhile, the temperature is the main indicator affecting the pressure output, and as the temperature rises, the fitting curve of the voltage and the pressure will be "raised", that is, the slope will increase, and the zero-point vision sensor is determined by its own characteristics.

[0046] In the direct temperature compensation method, the piezoresistive pressure sensor usually has a temperature-sensitive resistor for sensing temperature, the resistance value of the temperature-sensitive resistor has a certain relationship with the temperature, a constant current source is used for power supply, voltage data at multiple points are collected, and the temperature is directly fitted by voltage, and a second-order polynomial can generally meet the requirements.

[0047] In this embodiment, a PT100 thermal resistor is taken as an example for testing, Figure 4 a fitting curve graph of the normalized value of the output voltage of the temperature-sensitive resistor and the actual temperature, that is, a direct temperature compensation method, where the abscissa is the normalized value of the output voltage of the temperature-sensitive resistor, and the ordinate is the actual temperature, a fitting curve is obtained by a second-order polynomial fitting, it is proved that the relationship between the output voltage of the temperature-sensitive resistor and the pressure can be basically fitted by a second-order function, and is represented as:

[0048] y = 1047.1x 2 - 944.01x + 121.35

[0049] In the fitting formula, the polynomial coefficient is very large, and when the normalized value of the output voltage of the temperature-sensitive resistor on the abscissa axis fluctuates due to some reasons, the actual temperature obtained by fitting will be seriously affected, and a large error will occur.

[0050] Although the relationship between the resistance value of the temperature-sensitive resistor and the temperature is determined and reliable for a long time, the measurement of the digital quantity can only be represented by measuring the voltage of the resistor, and a constant current source is generally used to power the temperature-sensitive resistor, but the constant current source may fluctuate with the change of the temperature, that is, although the direct temperature calibration method is simple to use and has small calculation amount, when the constant current source is not stable enough, the relationship between the voltage and the temperature cannot be directly fitted by a polynomial to achieve high precision. ​

[0051] Therefore, the current calibration temperature compensation method is proposed, such as Figure 5 The fitting curve of the normalized output voltage of the temperature-sensitive resistor and the current, that is, the current calibration temperature compensation method; the horizontal axis in the figure is the normalized value of the output voltage of the temperature-sensitive resistor, and the vertical axis is the calculated current, which is expressed as:

[0052] y = -0.0101x 2 + 0.0073x + 0.0076

[0053] As can be seen from the above formula, as the temperature rises, the voltage output by the temperature-sensitive resistor increases, and the current will monotonically decrease to a certain extent, proving that the constant current source regularly decreases with the increase of temperature, and the regularity has a certain universality.

[0054] Taking a test of CG-SK1A type temperature and pressure sensor as an example, the output voltage of the pressure-sensitive bridge and the corresponding actual pressure at multiple standard temperature points are collected, the fitting curve at different temperatures is obtained, and then the slope and zero point of the fitting curve are obtained.

[0055] The fitting curve of the actual temperature and the slope of the pressure calibration curve is shown in Figure 6 , the horizontal axis is the actual temperature, the vertical axis is the slope of the pressure calibration curve, and it is expressed as y = 0.2355x + 64.802; the fitting curve of the actual temperature and the zero point of the pressure calibration curve is shown in Figure 7 , the horizontal axis is the actual temperature, the vertical axis is the zero point of the pressure calibration curve, and it is expressed as y = -0.000006x + 0.0033x + 0.9964. It can be seen that the slope and zero point of the pressure calibration curve increase with the increase of temperature, and the slope and zero point of the pressure calibration curve at each temperature point can be obtained accordingly.

[0056] The actual temperature can be calculated from the measured output voltage of the temperature-sensitive resistor, and the slope and zero point of the pressure calibration curve can be calculated according to the actual temperature. By introducing the slope and zero point into the calibration curve, the actual pressure can be calculated from the output voltage of the pressure-sensitive bridge.

[0057] The fitting curve of the normalized output voltage of the temperature-sensitive resistor, the normalized value of the output voltage of the pressure-sensitive bridge, and the actual pressure of the CG-SK1A type temperature and pressure sensor is shown in Figure 8 , the x-axis is the normalized output voltage of the temperature-sensitive resistor, the y-axis is the normalized value of the output voltage of the pressure-sensitive bridge, and the z-axis is the actual pressure, which is expressed as:

[0058] z = -7.009 + 28.81x + 86.64y - 370.4x 2 -202.2xy + 0.3836y 2 + 17.04x 3 + 233.1x 2 y - 1.877y2

[0059] From the above formula, it can be seen that good results can also be obtained by directly fitting a three-dimensional polynomial.

[0060] The sensitive structure of the above example is piezoresistive, and can also include sensitive structures such as piezoelectric and resonant, and each sensitive structure corresponds to a different range segment and is configured with a corresponding driving and acquisition circuit; at the same time, for the mutual interference problem of the detection signals of the multiple source sensitive structures and the high detection power consumption problem, a kind of sensitive structure can be selected as a normally open pressure detection module, the detection pressure signal value is first judged by the microprocessor, and the signal acquisition control of different sensitive structures is realized by using an analog switch.

[0061] In summary, the multi-source pressure sensor range calibration method provided by the application sets the detection core of the plurality of sensitive source structures, corresponds to the high-precision wide-range pressure detection of the plurality of range segments, and each range segment is configured with a corresponding calibration equation, the user can select different sensitive structures, range segments and calibration equations according to different application scenarios, and calibrate and output the initial pressure signal according to the corresponding calibration equation, the product has a wide range of applications, high precision, and different range segments can be selected according to actual application requirements to realize high-precision pressure measurement in the full range.

[0062] In the description of the application, it should be understood that the orientation or positional relationship indicated by the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inner", "outer", "front", "central", "both ends" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0063] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "setting", "connecting", "fixing", "rotating" and the like should be understood broadly, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship of two elements, unless otherwise explicitly limited, the above-mentioned terms in the present application can be understood according to the specific meaning of the above-mentioned terms in the present application according to the specific situation.

[0064] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A multi-source pressure sensor range calibration method, characterized by, The multi-source pressure sensor is used for measurement, at least two range sensitive structures are included in the multi-source pressure sensor, and each sensitive structure is connected with a corresponding detection circuit, a user selects a sensitive structure for measurement according to a required range, and a calibration process of a measurement value of the sensitive structure includes the following steps: The temperature calibration point and the pressure calibration point are set, and an equation obtained by fitting a normalized voltage value of a temperature sensor output and a normalized voltage value of a pressure-sensitive bridge output of a current circuit according to the calibration point is obtained, and the equation specifically includes: A force of the pressure calibration point is applied to the sensitive structure, an actual measurement value of the sensitive structure at the pressure calibration point is obtained, the pressure calibration point is taken as an output, the measurement value is taken as an input, and a first-order equation is used for fitting; Slopes and zero points of the first-order equations obtained at the temperature calibration points are used for secondary fitting to obtain a second-order equation of the temperature and the slopes and the zero points of the first-order equations; A current temperature is calculated according to the normalized voltage value of the temperature sensor output, the current temperature is input into the second-order equation of the slopes and the zero points to obtain corresponding slopes and zero points, and a first-order equation is established according to the obtained slopes and zero points; A measurement value obtained according to the current sensitive structure is input into the established first-order equation to obtain a calibrated pressure value. A current temperature value is obtained by a current calibration method.

2. A method of calibrating the range of a multi-source pressure sensor according to claim 1, characterized in that, The process of obtaining the current temperature value by the current calibration method includes:

3. A method of calibrating the range of a multi-source pressure sensor according to claim 2, characterized in that, A resistance-temperature relationship table provided by the temperature sensor is used to obtain resistances of the temperature sensor at different temperatures; An output voltage of the temperature sensor at the temperature is measured, the voltage is divided by the resistance to calculate a current, and a fitting curve of the current and the voltage at different temperatures is obtained; The output voltage of the temperature sensor is substituted into the fitting curve to obtain a related current, the voltage is divided by the current to obtain the resistance, and the current actual temperature is obtained by the resistance-temperature relationship of the temperature sensor. The process of obtaining the equation of the normalized voltage value of the temperature sensor output and the normalized voltage value of the pressure-sensitive bridge output of the current circuit according to the calibration point includes directly fitting the normalized voltage value of the temperature sensor output as an x-axis, the normalized voltage value of the pressure-sensitive bridge output as a y-axis, and the voltage calibration point as a z-axis.

4. The method of range calibration of a multi-source pressure sensor of claim 1, wherein, The sensitive structure includes a piezoresistive pressure sensor, a piezoelectric pressure sensor, and a resonant pressure sensor.

5. The method of claim 1, wherein, One sensitive structure in the multi-source pressure sensor is selected to be in an always-on state, and other sensitive structures are in an always-off state, and a measurement value of the always-on sensitive structure is used for judgment, if the measurement value of the always-on sensitive structure exceeds a measurement range, the always-on sensitive structure is closed, and a corresponding range sensitive structure is opened.

6. The method of range calibration of a multi-source pressure sensor of claim 1, wherein, ​

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