阅读说明：本技术 半导体式气体传感器的校准方法、系统和设备 (Calibration method, system and equipment of semiconductor type gas sensor ) 是由 刘思意 于 2019-08-30 设计创作，主要内容包括：本发明涉及一种半导体式气体传感器的校准方法、系统和设备,属于气体传感器技术领域,根据两个以上预设气体浓度以及该浓度下半导体式气体传感器的输出电压得到一条气体浓度与电压之间的自然对数拟合曲线,并根据该拟合曲线对量程范围内各个气体浓度尤其是报警点进行标定,而后,在半导体式气体传感器的实际应用环境下,求出报警点的偏差和参考点的偏差之间的相关函数,再根据这个函数计算出报警点补偿电压值,由标定的报警点电压值以及补偿电压值就可以得到更为准确的实际报警电压值。此种半导体式气体传感器可以减小环境因素的影响,降低误差,提高报警准确度。(The invention relates to a calibration method, a system and equipment of a semiconductor type gas sensor, belonging to the technical field of gas sensors. The semiconductor type gas sensor can reduce the influence of environmental factors, reduce errors and improve the alarm accuracy.)

1. A calibration method of a semiconductor type gas sensor is characterized by comprising the following steps:

measuring voltages output by the semiconductor type gas sensor corresponding to more than two preset gas concentrations in a preset parameter environment;

fitting the preset gas concentrations and the corresponding voltages output by the semiconductor type gas sensor into a natural logarithmic function curve;

calibrating the concentration of each gas and the output voltage of the semiconductor type gas sensor according to the natural logarithm curve;

the method comprises the steps of obtaining measured voltage measured by the semiconductor type gas sensor in an actual environment, obtaining a voltage compensation function according to the measured voltage and the calibrated voltage of the semiconductor type gas sensor, and calibrating the calibrated voltage according to the voltage compensation function.

2. The method of calibrating a semiconductor gas sensor according to claim 1, wherein the preset gas concentration comprises a preset alarm point gas concentration.

3. The method for calibrating a semiconductor gas sensor according to claim 1, wherein the step of calibrating the gas concentration and the voltage of the semiconductor gas sensor according to the natural logarithm curve further comprises the following steps:

and testing whether the semiconductor type sensor triggers an alarm in an alarm gas concentration interval allowed by the error, and if the alarm is triggered, judging that the calibration is successful.

4. The method for calibrating a semiconductor gas sensor according to claim 1, wherein the calibrating the gas concentration and the voltage of the semiconductor gas sensor according to the natural logarithm curve comprises:

and acquiring a reference point calibration voltage when the gas concentration is a reference point and an alarm point calibration voltage when the gas concentration is a preset alarm point gas concentration according to the natural logarithm curve, wherein the alarm point gas concentration is higher than the reference point gas concentration.

5. The method for calibrating a semiconductor type gas sensor according to claim 4, wherein the acquiring a measured voltage measured by the semiconductor type gas sensor in an actual environment includes:

measuring reference point actual measurement voltage when the gas concentration is a reference point and alarm point actual measurement voltage when the gas concentration is a preset alarm point gas concentration in an actual environment; the actual environment is the environment of the application site of the semiconductor gas sensor.

6. The method for calibrating a semiconductor gas sensor according to claim 5, wherein the step of obtaining a voltage compensation function from the measured voltage and the calibrated voltage comprises:

calculating a first difference value and a second difference value, wherein the first difference value is a difference value between the reference point actual measurement voltage and the reference point calibration voltage, and the second difference value is a difference value between the alarm point actual measurement voltage and the alarm point calibration voltage;

and acquiring a linear voltage compensation function of the alarm point voltage difference value along with the change of the reference point voltage difference value according to more than two groups of first difference values and second difference values.

7. The method for calibrating a semiconductor gas sensor according to claim 4, wherein the calibrating the calibration voltage of the semiconductor gas sensor according to the voltage compensation function comprises:

and obtaining a current alarm point compensation value according to the current reference point voltage background value and the voltage compensation function, and obtaining a calibrated alarm voltage value according to the alarm point calibration voltage and the alarm point compensation value, wherein the reference point voltage background value is an average value of voltage instantaneous values of the reference point participating in compensation in a period of time.

8. The method for calibrating a semiconductor gas sensor according to claim 7, wherein the calibrating the calibration voltage of the semiconductor gas sensor according to the voltage compensation value further comprises the steps of:

and if the alarm point compensation value is a negative number, compensating the calibration voltage of the alarm point.

9. The method for calibrating a semiconductor type gas sensor according to claim 7, further comprising the steps of:

recording a voltage sampling instantaneous value of a reference point at preset time intervals in a preset period;

and taking the average value of the voltage sampling instantaneous values of the reference points recorded in the preset period as the reference point voltage background value in the preset period.

10. The method for calibrating a semiconductor type gas sensor according to claim 9, further comprising the steps of:

if the average value of the voltage sampling instantaneous values of the reference point is within a preset range and the data dispersion and deviation of the voltage sampling instantaneous values of the reference point are within an error allowable range, recording the average value of the reference point instantaneous values as the reference point voltage background value of the period;

and if the average value of the voltage sampling instantaneous values of the reference point exceeds a preset range, or the data dispersion or deviation of the sampling value exceeds an error allowable range, returning to the step of recording one voltage sampling instantaneous value of the reference point at preset time intervals in the preset period.

11. A calibration system for a semiconductor gas sensor, comprising the following units:

a measuring unit for measuring voltages corresponding to two or more preset gas concentrations in a preset parameter environment and for obtaining the actual measurement voltage of the semiconductor gas sensor in an actual environment

The calibration unit is used for fitting each preset gas concentration and the corresponding voltage into a natural logarithmic function curve and calibrating the gas concentration and the voltage of the semiconductor type gas sensor according to the natural logarithmic function curve;

and the compensation unit acquires a linear voltage compensation function according to the measured voltage and the calibrated voltage and calibrates the calibrated voltage of the semiconductor type gas sensor according to the voltage compensation function.

12. A calibration apparatus for a semiconductor gas sensor, comprising a semiconductor gas sensor and a host computer connected thereto, wherein the semiconductor gas sensor comprises the semiconductor gas sensor, and the host computer is configured to send a predetermined gas concentration to the gas sensor, and the apparatus implements the calibration method for the semiconductor gas sensor according to any one of claims 1 to 10.

13. A computer storage medium having a computer program stored thereon, wherein the program, when executed by a processor, implements a method of calibrating a semiconductor type gas sensor according to any one of claims 1 to 10.

Technical Field

The invention relates to the technical field of gas sensors, in particular to a method, a system and equipment for calibrating a semiconductor type gas sensor.

Background

Semiconductor sensors are widely used in gas detectors because of their long life and low cost. For example, a methane gas sensor is a common semiconductor type gas sensor, and plays an important role in the field of fire fighting.

However, in the process of implementing the present invention, the inventors have found that the above-described techniques have at least the following problems: the semiconductor type gas sensor has narrow linear range, is more applied to detectors without digital display function, can only realize single-point alarm function, and has low gas concentration measurement precision and large measurement error in the full measuring range. Meanwhile, the semiconductor type sensor is greatly influenced by the environment (temperature, humidity and other gases), so that the working point drifts, and the semiconductor type sensor still cannot timely send out response when the gas concentration reaches or even exceeds the lower alarm limit.

Disclosure of Invention

Therefore, it is necessary to provide a method for calibrating a semiconductor gas sensor, which addresses the problems of large measurement error and operating point drift of the gas sensor.

In order to achieve the above object, the present invention provides a calibration method for a semiconductor gas sensor, comprising the steps of:

measuring voltages output by the semiconductor type gas sensor corresponding to more than two preset gas concentrations in a preset parameter environment;

fitting the concentrations of the preset gases and the voltages output by the corresponding semiconductor type gas sensors into a natural logarithmic function curve;

calibrating the concentration of each gas and the output voltage of the semiconductor type gas sensor according to a natural logarithm curve;

the method comprises the steps of obtaining measured voltage measured by the semiconductor type gas sensor in an actual environment, obtaining a voltage compensation function according to the measured voltage and the calibrated voltage of the semiconductor type gas sensor, and calibrating the calibrated voltage according to the voltage compensation function.

According to the calibration method of the semiconductor gas sensor, a natural logarithm fitting curve between gas concentration and voltage is obtained according to more than two preset gas concentrations and the output voltage of the semiconductor gas sensor under the gas concentrations, the curve represents the voltage corresponding to each gas concentration in a measuring range in a preset environment parameter within an error range, a voltage compensation function between the deviation of an alarm point and the deviation of a reference point is solved under the actual application environment of the semiconductor gas sensor, then the compensation voltage value of the alarm point is calculated according to the function, and a more accurate actual alarm voltage value can be obtained according to the calibrated alarm point voltage value and the compensation voltage value, namely, the alarm error is reduced, the accuracy of a working point is improved, and the problem of deviation of the working point is reduced.

In one embodiment, the preset gas concentration in the voltages output by the semiconductor type gas sensor corresponding to more than two preset gas concentrations is measured to comprise the alarm point concentration.

In one embodiment, after the step of calibrating the gas concentration and the voltage of the semiconductor gas sensor according to the natural logarithm curve, the method further comprises the following steps:

and testing whether the semiconductor type sensor triggers an alarm in an alarm gas concentration interval allowed by the error, and if the alarm is triggered, judging that the calibration is successful.

In one embodiment, acquiring a measured voltage measured by the semiconductor type gas sensor in an actual environment includes:

measuring reference point actual measurement voltage when the gas concentration is a reference point and alarm point actual measurement voltage when the gas concentration is a preset alarm point gas concentration in an actual environment; wherein the actual environment is the environment of the application site of the semiconductor gas sensor.

In one embodiment, the step of obtaining the voltage compensation function according to the measured voltage and the calibration voltage comprises:

calculating a first difference value and a second difference value, wherein the first difference value is a difference value between a reference point actual measurement voltage and a reference point calibration voltage, and the second difference value is a difference value between an alarm point actual measurement voltage and an alarm point calibration voltage;

and acquiring a linear voltage compensation function of the alarm point voltage difference value along with the change of the reference point voltage difference value according to more than two groups of first difference values and second difference values.

In one embodiment, calibrating the calibration voltage of the semiconductor gas sensor according to the voltage compensation function comprises:

and obtaining a current alarm point compensation value according to the current reference point voltage background value and the voltage compensation function, and obtaining a calibrated alarm voltage value according to the alarm point calibration voltage and the alarm point compensation value, wherein the reference point voltage background value is the average value of the voltage instantaneous values of the reference points participating in compensation within a period of time.

In one embodiment, the calibration voltage of the semiconductor gas sensor is calibrated according to a voltage compensation function, and the method further comprises the following steps:

and if the alarm point compensation value is a negative number, compensating the calibration voltage of the alarm point.

In one embodiment, the calibration voltage of the semiconductor gas sensor is calibrated according to a voltage compensation function, and the method further comprises the following steps:

recording a voltage sampling instantaneous value of a reference point at preset time intervals in a preset period;

and taking the average value of the voltage sampling instantaneous values of the reference points recorded in the preset period as the reference point background value voltage in the preset period.

In one embodiment, the calibration voltage of the semiconductor gas sensor is calibrated according to a voltage compensation function, and the method further comprises the following steps:

if the average value of the voltage sampling instantaneous values of the reference points is within a preset range and the data dispersion and deviation of the voltage sampling instantaneous values of the reference points are within an error allowable range, recording the average value of the reference point instantaneous values as the reference point background value voltage of the period;

and if the average value of the voltage sampling instantaneous values of the reference points exceeds a preset range or the data dispersion and deviation of the sampling values exceed an error allowable range, returning to the step of recording one voltage sampling instantaneous value of the reference points at preset time intervals in a preset period.

According to the obtained natural logarithm curve and the preset gas concentration of the alarm point, the calibration voltage of the alarm point and the reference point calibration voltage can be obtained, and then according to more than two groups of actually measured alarm point voltages and reference point voltages, a curve that the alarm point voltage deviation value changes along with the reference point voltage deviation value can be obtained, namely a voltage compensation curve, the voltage compensation curve is obtained by integrating environmental factors such as temperature, humidity and other gas influences according to an actual application scene, the compensation is more comprehensive and accurate, and the accuracy of the alarm voltage is further higher.

A calibration system for a semiconductor type gas sensor, comprising the following units:

a measuring unit for measuring voltages corresponding to two or more preset gas concentrations in a preset parameter environment and for obtaining the actual measurement voltage of the semiconductor gas sensor in an actual environment

The calibration unit is used for fitting each preset gas concentration and the corresponding voltage into a natural logarithm function curve and calibrating the gas concentration and the voltage of the semiconductor gas sensor according to the natural logarithm curve;

and the compensation unit acquires a linear voltage compensation function according to the measured voltage and the calibrated voltage and calibrates the calibrated voltage of the semiconductor type gas sensor according to the voltage compensation function.

In one embodiment, the calibration unit fits each preset gas concentration and the corresponding voltage to a natural logarithm function curve, which includes the preset gas concentration at the alarm point.

In one embodiment, the calibration unit is further configured to implement the following steps:

and testing whether the semiconductor type sensor triggers an alarm in an alarm gas concentration interval allowed by the error, and if the alarm is triggered, judging that the calibration is successful.

In one embodiment, the calibration unit is configured to obtain a reference point calibration voltage when the gas concentration is a reference point and an alarm point calibration voltage when the gas concentration is a preset alarm point gas concentration according to a natural logarithm curve.

In one embodiment, the measurement unit is configured to measure, in an actual environment, a reference point measured voltage when the gas concentration is a reference point, and an alarm point measured voltage when the gas concentration is a preset alarm point gas concentration. The actual environment is the environment of the application site of the semiconductor gas sensor.

In one embodiment, the compensation unit is configured to calculate a first difference value and a second difference value, where the first difference value is a difference value between a reference point measured voltage and a reference point calibration voltage, the second difference value is a difference value between an alarm point measured voltage and an alarm point calibration voltage, and a linear voltage compensation function of the alarm point voltage difference value changing with the reference point voltage difference value is obtained according to two or more groups of the first difference value and the second difference value.

In one embodiment, the compensation unit is configured to obtain a current alarm point compensation value according to a current reference point voltage background value and a voltage compensation function, and obtain a calibrated alarm voltage value according to an alarm point calibration voltage and the alarm point compensation value, where the reference point voltage background value is an average value of instantaneous voltage values of the reference point participating in compensation over a period of time.

In one embodiment, the compensation unit is further configured to record a voltage sample instantaneous value of the reference point every preset time during a preset period, and use an average value of the voltage sample instantaneous values of the reference point recorded during the preset period as a reference point voltage background value during the preset period.

In one embodiment, the compensation unit is used for judging, if the average value of the voltage sampling instantaneous values of the reference point is within a preset range and the data dispersion and the deviation of the voltage sampling instantaneous values of the reference point are within an error allowable range, recording the average value of the reference point instantaneous values as the reference point voltage background value of the period;

and if the average value of the voltage sampling instantaneous values of the reference points exceeds a preset range or the data dispersion or deviation of the sampling values exceeds an error allowable range, returning to the step of recording one voltage sampling instantaneous value of the reference points at preset time intervals in a preset period.

In one embodiment, the compensation unit compensates the calibration voltage of the alarm point when the alarm point compensation value is negative.

The semiconductor type gas sensor calibration equipment comprises a semiconductor type gas detector and an upper computer connected with the semiconductor type gas detector, wherein the semiconductor type gas detector comprises a semiconductor type gas sensor, and the upper computer is used for sending a preset gas concentration to the gas detector.

A computer storage medium having stored thereon a computer program which, when executed by a processor, implements the calibration method of the semiconductor gas sensor described above.

The system, the equipment and the computer storage medium for calibrating the semiconductor gas sensor obtain the deviant of the voltage of the alarm point by real-time measurement of the voltage of the reference point through natural logarithmic curve fitting and calibration between the voltage and the gas concentration and by combining the functional relation between the compensation voltage difference value of the alarm point and the voltage difference value of the reference point, thereby realizing the accurate calculation of the voltage of the alarm point of the semiconductor gas sensor under the influence of changed environmental factors.

Drawings

FIG. 1 is a schematic flow chart of a method for calibrating a semiconductor gas sensor in one embodiment;

FIG. 2 is a schematic diagram of a calibration system for a semiconductor gas sensor in one embodiment;

FIG. 3 is a schematic structural diagram of a calibration system of a semiconductor type gas sensor in another embodiment;

FIG. 4 is a graph of an example of a characteristic curve and fitted curve in the 0-10% LEL range for a semiconductor sensor in one embodiment;

FIG. 5 is a graph of reference point difference versus alarm point difference for one embodiment;

FIG. 6 is a flow diagram of reference point learning in one embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

It should be noted that the term "first \ second" referred to in the embodiments of the present invention is only used for distinguishing similar objects, and does not represent a specific ordering for the objects, and it should be understood that "first \ second" may exchange a specific order or sequence order if allowed. It should be understood that "first \ second" distinct objects may be interchanged under appropriate circumstances such that embodiments of the invention described herein may be practiced in sequences other than those illustrated or described herein.

The terms "comprises" and "comprising," and any variations thereof, of embodiments of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or (module) elements is not limited to only those steps or elements but may alternatively include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

The calibration method of the semiconductor type gas sensor can be applied to various gas concentration monitoring and alarm scenes. Under the scene that combustible gas leakage is likely to occur, the accuracy of the alarm of the combustible gas detector plays a vital role in ensuring personal and property safety. The semiconductor type gas sensor is widely applied to a gas detector due to low price and long service life, and accurate alarm of the semiconductor type gas sensor can be achieved through the scheme of the application.

Referring to fig. 1, a flow chart of a calibration method of a semiconductor gas sensor according to the present invention is shown. The calibration method of the semiconductor type gas sensor in this embodiment includes the steps of:

step S110: measuring voltages output by the semiconductor type gas sensor corresponding to more than two preset gas concentrations in a preset parameter environment;

in this step, the preset parameter environment is a calibration environment of the sensor, and is generally given directly on the specification of the sensor, and includes parameters such as temperature and humidity. These parameters are typically a range, for example a nominal temperature of 20-25 degrees, within which a fixed value is selected when the predetermined parameter is selected. In the preset environment, more than two gas concentrations are given through an upper computer, and the output voltage of the gas sensor under each gas concentration is measured, so that a measurement data set with one-to-one correspondence between the gas concentrations and the output voltages is obtained.

Step S120: fitting the concentrations of the preset gases and the voltages output by the corresponding semiconductor type gas sensors into a natural logarithmic function curve;

in this step, a coordinate axis in which the horizontal axis is the gas concentration and the vertical axis is the sensor output voltage is established, and the measured data set is plotted into the coordinate axis. These points are then fitted to a natural logarithmic curve and the coefficients a and b for y ═ aln (x) + b are determined, i.e. the functional expression of the fitted curve is determined. Where x is the gas concentration and y is the output voltage of the sensor.

Step S130: calibrating the concentration of each gas and the output voltage of the semiconductor type gas sensor according to a natural logarithm curve;

in this step, the output voltage of the sensor corresponding to each gas concentration may be calibrated according to the calculated function expression of the fitting curve.

Step S140: the method comprises the steps of obtaining measured voltage measured by the semiconductor type gas sensor in an actual environment, obtaining a voltage compensation function according to the measured voltage and the calibrated voltage of the semiconductor type gas sensor, and calibrating the calibrated voltage according to the obtained voltage compensation function.

In this step, the sensor is placed in the environment of actual use. Under the influence of temperature, humidity and other gases, the output voltage of the sensor changes at a given gas concentration, which also results in a shift of the alarm point voltage. Thus, by observing the change of the sensor output voltage and the calibration voltage in the actual application environment and quantizing the change relationship into a function, an offset value of the voltage, or referred to as a compensation value, can be obtained from the function. Finally, a more accurate voltage value of the alarm point is obtained through the calibration value and the compensation value, so that the alarm is more accurate and timely.

In the embodiment, a natural logarithm fitting curve between gas concentration and voltage is obtained according to more than two preset gas concentrations and the output voltage of the semiconductor type gas sensor under the concentrations, the curve represents the voltage corresponding to each gas concentration in a measuring range in an error range in preset environment parameters, a voltage compensation function between the deviation of an alarm point and the deviation of a reference point is solved under the actual application environment of the semiconductor type gas sensor, then the compensation voltage value of the alarm point is calculated according to the function, and a more accurate actual alarm voltage value can be obtained according to the calibrated alarm point voltage value and the compensation voltage value, namely, the alarm error is reduced, the accuracy of a working point is improved, and the deviation problem of the working point is reduced.

In one embodiment, the alarm point gas concentration and the output voltage are used as one of the sets of data when the coefficients of the natural log curve are found.

In this embodiment, since the alarm point is a response operating point of the sensor and is a main object of calibration in practical application, taking the alarm point when calculating the coefficient can reduce the fitting error near the alarm point.

In one embodiment, after the step of calibrating the gas concentration and the voltage of the semiconductor type gas sensor according to the natural logarithm curve, the method further comprises the following steps:

and testing whether the semiconductor type sensor triggers an alarm in an alarm gas concentration interval allowed by the error, and if the alarm is triggered, judging that the calibration is successful. Specifically, in practical application, the alarm concentration of the gas is not only a concentration point but also an error allowable range, in order to ensure the calibration accuracy, whether the sensor makes an alarm response in an alarm gas concentration interval with the error allowable range can be tested, the sensor alarms before the lower limit of the interval and is called early report, the sensor alarms after the upper limit of the interval and is called late report, the early report and the late report do not meet the requirements and cannot pass the test, and only the sensor which makes the alarm response in the interval passes the test, the calibration is regarded as successful.

In the embodiment, a calibration verification step is added after the gas concentration and the voltage of the semiconductor type gas sensor are calibrated according to the natural logarithm curve. The process further improves the calibration accuracy, so that the difference between the alarm actual value and the set value of the calibrated gas sensor is far smaller than the industrially allowable error range.

In one embodiment, calibrating the gas concentration and voltage of the semiconductor type gas sensor according to a natural logarithm curve comprises the following steps:

and acquiring a reference point calibration voltage when the gas concentration is a reference point and an alarm point calibration voltage when the gas concentration is a preset alarm point gas concentration according to the natural logarithm curve, wherein the alarm point gas concentration is higher than the reference point gas concentration.

In this embodiment, the voltage of the alarm point is calibrated according to the obtained natural logarithm curve, and the calibrated voltage of the alarm point is the working voltage of the sensor in the preset standard environment. Additionally, in the embodiment, a reference point is selected for calibration, and the reference point is a concentration point which is easy to observe, so that the reference point can be compared with the voltage of the alarm point in an actual application environment, and the voltage change of the alarm point is predicted from the voltage change of the reference point.

Preferably, the reference point may select the concentration of the detected gas in the normal state. For example, if a gas is present in air at 1% VOL, then under normal conditions, the 1% VOL can be chosen as the reference point, since this is the most easily monitored concentration. For air contents much less than one percent, the zero point may be selected as the reference point.

In one embodiment, acquiring a measured voltage measured by the semiconductor type gas sensor in an actual environment comprises:

measuring reference point actual measurement voltage when the gas concentration is a reference point and alarm point actual measurement voltage when the gas concentration is a preset alarm point gas concentration in an actual environment; the actual environment is the environment of the application site of the semiconductor gas sensor.

In this embodiment, the sensor is placed in an actual application environment and measures the measured voltage of the alarm point in the environment, which is based on calibration, integrates various environmental factors in actual application, and further calibrates the voltage of the alarm point. Additionally, in the embodiment, a reference point is selected for calibration, and the reference point is a concentration point which is easy to observe, so that the reference point can be compared with the voltage of the alarm point in an actual application environment, and the voltage change of the alarm point is predicted from the voltage change of the reference point. Preferably, the reference point may select the concentration of the detected gas in the normal state.

In one embodiment, the step of deriving the voltage compensation function from the measured voltage and the calibration voltage comprises:

calculating a first difference value and a second difference value, wherein the first difference value is a difference value between a reference point actual measurement voltage and a reference point calibration voltage, and the second difference value is a difference value between an alarm point actual measurement voltage and an alarm point calibration voltage;

and acquiring a linear voltage compensation function of the alarm point voltage difference value along with the change of the reference point voltage difference value according to more than two groups of first difference values and second difference values.

Specifically, in this embodiment, a functional relationship between a difference between the measured voltage and the calibration voltage at the alarm point and a difference between the measured voltage and the calibration voltage at the reference point is found through the measured data, and the difference may also be referred to as a compensation value, so that the functional relationship may also be referred to as a compensation function.

Preferably, the compensation function may be fuzzy-like into a linear formula Δ y ═ c × Δ x + d, where x is the reference point voltage, Δ x is the difference between the reference point measured voltage and the calibration voltage, y is the alarm point voltage, and Δ y is the difference between the alarm point measured voltage and the calibration voltage. And obtaining the coefficient c and the constant d through multiple groups of measured data and fitting.

In this embodiment, by finding a functional relationship between a difference between a measured voltage and a calibrated voltage of a reference point and a difference between a measured voltage and a calibrated voltage of an alarm point, the measured voltage of the reference point is convenient to observe and measure, and the measured voltage of the alarm point is a predicted value for alarming. Through the functional relation, the difference value between the measured voltage and the calibrated voltage of the alarm point, namely the voltage compensation value, can be calculated more accurately according to the measured voltage of the reference point, so that the accuracy of the voltage of the alarm point is further improved on the basis of the calibrated voltage. In addition to the linear functions mentioned in the above embodiments, it is also possible to further improve the compensation accuracy by fitting the relationship between the voltage difference value of the reference point and the voltage difference value of the alarm point to the closest one by observing the actual measurement data.

In one embodiment, calibrating the calibration voltage of the semiconductor gas sensor according to the voltage compensation function comprises:

and obtaining a current alarm point compensation value according to the current reference point voltage background value and the voltage compensation function, and obtaining a calibrated alarm voltage value according to the alarm point calibration voltage and the alarm point compensation value, wherein the reference point voltage background value is the average value of the voltage instantaneous values of the reference points participating in compensation within a period of time.

In this embodiment, after the compensation function is obtained, when the sensor is actually applied, the voltage difference value of the alarm point can be calculated in real time by monitoring the difference value between the measured voltage and the calibration voltage of the reference point, and the alarm voltage can be compensated on the basis of the calibration value of the alarm voltage in real time. In addition, a background value voltage is introduced during calculation, the background value voltage is an average value of instantaneous values of the voltage in a period of time and a period of reference point participating in compensation, the background value is unchanged in a single period, namely the same value is used for participating in compensation of the alarm point, but each instantaneous value is still converted into a gas concentration value in real time and difference compensation is carried out. For example, for a single interval time span of 80 minutes, the background value would not be updated for 80 minutes, but the detector would sample multiple transients per second, each of which would be converted to a gas concentration value, except that the background value for one of the input parameters would be the same value. In a time period, the reference point voltage measured values participating in the voltage compensation of the alarm point are all the base value voltage, so that the calculation resources are saved, and the calculation efficiency is increased.

In one embodiment, calibrating the calibration voltage of the semiconductor gas sensor according to the voltage compensation value further comprises the following steps:

and if the alarm point compensation value is a negative number, compensating the calibration voltage of the alarm point.

In this embodiment, during compensation, when the sensitivity of the sensor becomes small, the reference point voltage is negatively biased, that is, the difference between the measured reference point voltage and the reference point calibration voltage is negative, and the alarm point voltage is also negatively biased, so that the gas detector including the sensor before compensation will generate the phenomenon of late alarm, and the late alarm phenomenon after compensation is reduced. However, if the sensitivity of the sensor becomes high, the zero point voltage is biased positively, and the alarm point voltage is also biased positively, so that the forward compensation is not favorable for the real-time performance of the alarm of the detector, and in this case, the compensation is not performed.

According to practical application, the voltage at the alarm point is compensated when the alarm voltage of the sensor is negatively biased, that is, the compensation value is a negative number, because the alarm late-alarm phenomenon occurs in this case, which may cause serious consequences, the alarm voltage must be compensated. And under the condition that the alarm voltage is positively biased, the early warning phenomenon can occur in the alarm, but the early warning is harmless, so the condition table does not compensate the alarm voltage.

In one embodiment, calibrating the calibration voltage of the semiconductor gas sensor according to the voltage compensation function comprises:

recording a voltage sampling instantaneous value of a reference point at preset time intervals in a preset period;

and taking the average value of the voltage sampling instantaneous values of the reference points recorded in the preset period as the reference point background value voltage in the preset period.

Further, if the average value of the voltage sampling instantaneous values of the reference points is within a preset range and the data dispersion and the deviation of the voltage sampling instantaneous values of the reference points are within an error allowable range, recording the average value of the reference point instantaneous values as the reference point background value voltage of the period;

and if the average value of the voltage sampling instantaneous values of the reference points exceeds a preset range or the data dispersion and deviation of the sampling values exceed an error allowable range, returning to the step of recording one voltage sampling instantaneous value of the reference points at preset time intervals in a preset period.

Specifically, the background voltage is an average value of instantaneous values of the voltage in a period of time, which is a fixed time interval that can be set to 12h, 24h, 48h, etc. according to the accuracy requirement of the detector, of the reference point participating in the compensation. The interval includes various meanings, firstly, in the current time interval, the average value of the samples should be in a reasonable range; secondly, the background value of the current period and the background value of the previous period should not have abnormal large-amplitude change; in addition, the data dispersion and deviation of all voltage sample transients should also be within the tolerance range. Only the average value of the instantaneous values of the voltage samples that simultaneously satisfy the above conditions will be successfully recorded as the current background voltage, and failure of either condition will result in the start of a sample of a new cycle.

In this embodiment, since the measured voltage of the reference point is needed to be used when calculating the compensation voltage of the alarm point, and the measured voltage is changed in real time, if the compensation voltage value is calculated at each moment, a large calculation cost is caused, and there is no need for real-time calculation for the gas detector, therefore, the concept of the background voltage is introduced here, the measured voltage is sampled at regular time within a time period, and then the average value of the samples is calculated, thereby greatly saving calculation resources. In addition, the dispersion and deviation of the sampling data are required to be within an error range from the statistical perspective, and the difference value between the obtained background value point voltage and the background value voltage of the previous period is required to be within a reasonable fluctuation range, so that the finally obtained background value voltage is reasonable and reliable.

According to the calibration method of the semiconductor gas sensor, embodiments of the calibration system of the semiconductor gas sensor according to the present invention are also provided, and the following describes in detail embodiments of the calibration system of the semiconductor gas sensor.

Fig. 2 is a schematic structural diagram of a calibration system of a semiconductor gas sensor according to an embodiment. The calibration system of the semiconductor type gas sensor in this embodiment includes:

a measuring unit 210, configured to measure voltages corresponding to two or more preset gas concentrations in a preset parameter environment and obtain a measured voltage measured by the semiconductor type gas sensor in an actual environment,

a calibration unit 220, configured to fit each preset gas concentration and corresponding voltage to a natural logarithm function curve and calibrate the gas concentration and the voltage of the semiconductor gas sensor according to the natural logarithm function curve;

and the compensation unit 230 is configured to obtain a linear voltage compensation function according to the measured voltage and the calibrated voltage, and calibrate the calibrated voltage of the semiconductor gas sensor according to the voltage compensation function.

In the present embodiment, the measurement unit 210 is responsible for measuring the output voltage of the semiconductor type sensor, the measurement result in the preset environment is output to the calibration unit 220 for fitting the natural logarithm function curve, and the measurement result in the actual environment is output to the compensation unit 230 for calculating the voltage compensation function.

The calibration unit 220 receives the voltage measurement result in the preset environment sent by the measurement unit 210, and in combination with the corresponding gas concentration, may calculate the coefficient of the natural logarithm function curve and calibrate the semiconductor gas sensor according to the curve.

The compensation unit 230 receives the voltage measurement result in the actual environment sent by the measurement unit 210, obtains a linear voltage compensation function according to the measured voltage and the calibration voltage before the sensor is used, and then calibrates the calibration voltage of the semiconductor gas sensor according to the measured voltage and the voltage compensation function when the sensor is put into use.

In one embodiment, the calibration unit 220 includes preset alarm point gas concentrations when fitting each preset gas concentration and corresponding voltage to a natural logarithm function curve.

In one embodiment, the calibration unit 220 is further configured to implement the following steps:

and configuring an alarm voltage interval of the gas sensor according to a preset alarm gas concentration interval, testing whether the alarm of the semiconductor type sensor is triggered or not when the upper limit and the lower limit of the alarm gas concentration interval are reached, and judging that the calibration is successful if the alarm is triggered.

In one embodiment, the calibration unit 220 is configured to obtain a reference point calibration voltage when the gas concentration is a reference point and an alarm point calibration voltage when the gas concentration is a preset alarm point gas concentration according to a natural logarithm curve.

In one embodiment, the measurement unit 210 is configured to measure, in an actual environment, a reference point measured voltage when the gas concentration is a reference point, and an alarm point measured voltage when the gas concentration is a preset alarm point gas concentration. The actual environment is the environment of the application site of the semiconductor gas sensor.

In one embodiment, the compensation unit 230 is configured to calculate a first difference value and a second difference value, where the first difference value is a difference value between a reference point measured voltage and a reference point calibration voltage, and the second difference value is a difference value between an alarm point measured voltage and an alarm point calibration voltage, and obtain a linear voltage compensation function of the alarm point voltage difference value along with a change of the reference point voltage difference value according to more than two sets of the first difference value and the second difference value.

In one embodiment, as shown in fig. 3, the compensation unit 230 further includes a sampling unit 232 and a voltage background learning unit 234, configured to obtain a current alarm point compensation value according to a current reference point voltage background value and a voltage compensation function, and obtain a calibrated alarm voltage value according to an alarm point calibration voltage and the alarm point compensation value, where the reference point voltage background value is an average value of instantaneous voltage values of the reference point participating in compensation over a period of time.

Further, the sampling unit 232 is configured to record a voltage sampling instantaneous value of the reference point every preset time within a preset period, and the voltage background value learning unit 234 is configured to use an average value of the voltage sampling instantaneous values of the reference point recorded within the preset period as a reference point voltage background value within the preset period.

In one embodiment, the voltage background learning unit 234 is configured to record the average value of the instantaneous voltage sample value of the reference point as the reference point voltage background of the period when the average value of the instantaneous voltage sample value of the reference point is within a preset range and the data dispersion and deviation of the instantaneous voltage sample value of the reference point are within an error allowable range;

when the average value of the voltage sampling instantaneous values of the reference point exceeds the preset range, or the data dispersion or deviation of the sampling values exceeds the error allowable range, the sampling unit 232 records one voltage sampling instantaneous value of the reference point at preset time intervals in the preset period again.

In one embodiment, the compensation unit 230 compensates the calibration voltage of the alarm point when the alarm point compensation value is negative.

The calibration system of the semiconductor type gas sensor according to the embodiment of the present invention corresponds to the calibration method of the semiconductor type gas sensor, and the technical features and the advantageous effects described in the embodiment of the calibration method of the semiconductor type gas sensor are applicable to the embodiment of the calibration system of the semiconductor type gas sensor.

The semiconductor gas sensor calibration device comprises a semiconductor gas detector and an upper computer connected with the semiconductor gas detector, wherein the semiconductor gas detector comprises the semiconductor gas sensor, an instrument capable of displaying the output voltage of the semiconductor gas sensor and a processor capable of processing data. The upper computer is used for sending preset gas concentration to the gas detector.

According to the calibration equipment of the semiconductor type gas sensor, the executable program is run on the processor, so that the calibration method of the semiconductor type gas sensor can be realized, the accuracy of the semiconductor type gas sensor can be improved, and the alarm error can be reduced.

A computer storage medium having a computer program stored thereon, wherein the program, when executed by a processor, implements the method of calibrating a semiconductor gas sensor described above.

Those skilled in the art will understand that: all or part of the steps for realizing the method embodiments can be completed by hardware related to program instructions, the program can be stored in a computer readable storage medium, and the program executes the steps comprising the method embodiments when executed; and the aforementioned storage medium includes: various media that can store program codes, such as a removable Memory device, a Random Access Memory (RAM), a Read-Only Memory (ROM), a magnetic disk, and an optical disk.

In a specific embodiment, the alarm threshold has different standards according to different gases, in this example, methane is taken as an example, the lowest volume percentage concentration of combustible gas in the air that can explode is called the lower explosion limit, and the lower gas explosion limit of methane is 5.0% VOL, 50000PPM, and 100.0% LEL. For a detector with only one alarm value, the set value is in the LEL range of [ 1.0%, 25.0% ], and common alarm values of the detector include 4% LEL (2000PPM), 5% LEL (2500PPM) and 7% LEL (3500 PPM). The difference between the actual alarm action value and the alarm set value should not exceed +/-3% LEL; the measurement error in the range of measuring range should not exceed +/-5% LEL.

The actually measured voltage value and the gas concentration value of the semiconductor sensor are close to a natural logarithmic function curve, and the calibration process is actually a process of fitting the actually measured sensor characteristic curve into a natural logarithmic curve. And mapping the sampling points to a coordinate axis with the horizontal axis as gas concentration and the vertical axis as sampling voltage, and obtaining the coefficient of the natural logarithm function according to coordinate points after fitting.

In the process, an upper computer is required to send preset gas concentration to the sensor, the calibration process is completed under a preset environment parameter, generally, the preset environment is a standard working environment given on a specification of the semiconductor type sensor, under each gas concentration set by the upper computer, the detector equipment can output corresponding voltage true values, and more than two groups of sampling data groups corresponding to the concentrations and the voltages are stored.

Two groups of non-zero coordinates in a sampling data group are selected, one group of alarm points is selected, and a coefficient a and a constant b of a natural logarithmic function y ═ aln (x) + b are obtained according to the two groups of data, wherein x is gas concentration, and y is sampling voltage. Fig. 4 shows the characteristic curves of the semiconductor sensor in the range of 0-10% LEL and the fitted curve thereof.

After calibration, the equipment can be subjected to qualification verification: the upper limit and the lower limit of the alarm action value range are input through the upper computer, the alarm states of the detectors at the upper limit concentration and the lower limit concentration are tested, if the detectors at the two gas concentrations alarm normally, the verification is passed, and the calibration is successful.

The difference value between the calibrated alarm actual value and the set value is far smaller than the error range of +/-3% LEL, and the fitting curve of the sampling voltage and the gas concentration value in the range [0,5000] PPM is far smaller than the error range of +/-5% LEL.

The sensitivity of the calibrated equipment measured in a changing environment is obviously influenced by factors such as temperature, humidity or interference gas and the like. The sensitivity changes along with the change of the environment, and the influence factors are complex and difficult to be quantized one by one. Based on the knowledge that the sensitivity is in a multiple relation to the characteristic curve of the sensor, a simplified linear compensation algorithm is found, wherein under the comprehensive action of environmental factors, the difference compensation is carried out on the alarm point calibration value through the difference between the zero point voltage real-time value and the zero point calibration value by taking the zero point as a reference point.

In a plurality of groups of measured data, comparing the difference value relationship of two points of voltage, and obtaining a linear compensation formula by fuzzy similarity: and the coefficient c and d of the constant are related to the voltage division ratio of the circuit. Fig. 5 shows a linear compensation curve obtained by a curve of the difference between two points and the difference between alarm points and their fuzzy similarities.

The system is designed by using directional compensation, and the compensation rule integrally accords with the following rule:

the sensitivity is reduced, the zero voltage is negatively biased, the voltage of the alarm point is negatively biased, the device reports late before compensation, and the phenomenon of reporting late after compensation is generally reduced;

the sensitivity is increased, the zero voltage is positively biased, the voltage of the alarm point is positively biased, and the positive compensation is not favorable for the real-time alarm of the equipment and is not compensated.

In addition, the device is provided with a background value learning function, wherein the background value is the average value of the instantaneous voltage values of the reference points participating in compensation within a period of time and a period of time. In this embodiment, the reference point background value is a zero background value, which is an average value of 36 sets of zero instantaneous values recorded at 80min intervals in a 48h period. If the average value is within an allowable error range and the dispersion and deviation of the sampling value are within a preset error range, the background value is regarded as successful learning, and the average value is recorded as the latest zero background value and is used for calculating the compensation value of the current alarm point. The background value learning flow is shown in fig. 6.

Finally, according to the calibration value and the compensation value of the alarm point, a more accurate alarm value after calibration can be obtained, and the error caused by the environmental factors is reduced to +/-3% LEL in the full-range by the equipment subjected to zero difference compensation.

The scheme solves the problems of large measurement error and working point drift of the semiconductor type gas sensor through two steps of calibration and compensation. In the calibration stage, a natural logarithmic curve is adopted to fit a characteristic curve of the semiconductor type gas sensor, so that the calibration of each gas concentration in the measuring range is within an error range. In the compensation stage, a linear compensation function is adopted, the offset of the alarm point is mapped to the offset of the zero point, and the compensation value of the voltage of the alarm point is calculated by monitoring the offset value of the voltage of the zero point in real time. On the basis of obtaining the calibration voltage of the alarm point, the semiconductor type gas sensor is compensated, so that the accuracy of the alarm point is further improved, and accurate alarm response within an error range can be realized.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.