KR102588967B1 - Method of calibrating gas sensor and self-calibrating system performing method - Google Patents

Abstract

A gas concentration measurement control method of a gas measurement system including a gas sensor for measuring gas concentration according to an embodiment of the present invention includes the steps of: storing a reference resistance value of the gas sensor for measuring gas concentration by the gas sensor; Using the gas sensor, determining whether there is gas around the gas sensor at a first time after starting to measure the gas concentration, determining that there is no gas around the gas sensor at the first time In this case, it may include updating the resistance value of the gas sensor at the first time point as the reference resistance value.

Description

Method for self-calibrating a gas sensor and a gas sensor calibration system performing the method {METHOD OF CALIBRATING GAS SENSOR AND SELF-CALIBRATING SYSTEM PERFORMING METHOD}

The present invention relates to gas sensors, and more specifically, to a gas sensor calibration system that provides self-calibration and a gas sensor self-calibration method.

Gas sensors can be used for a variety of purposes. For example, a gas sensor can be mounted on an air purifier and used to measure the quality of air around the air purifier. Additionally, gas sensors can be included in portable devices, such as mobile phones, and can be used by users of portable devices to recognize the quality of surrounding air.

Conventional gas sensors have a problem in that accurate gas detection is difficult as the gas sensor ages and its reactivity changes depending on the usage time. In addition, since the reactivity data and data correction of these gas sensors must be measured by directly injecting gas, a lot of manpower and time are required for reactivity correction.

In particular, among gas sensors, MOS (Metal Oxide Semiconductor) gas sensors reduce the adsorption of oxygen necessary for recovery depending on the usage time and frequency of use, and the gas sensor resistance value changes, which may display incorrect gas concentration. In addition, since the gas sensor resistance value of the MOS gas sensor easily changes depending on foreign substances such as dust or the installation location, there is a problem of misjudging the presence of gas or incorrectly measuring the gas concentration due to fluctuations in responsiveness.

Since the responsiveness of MOS gas sensors is sensitive to temperature, a correction method is needed. Temperature correction methods based on conventional measurement data are relatively accurate for specific sensors, but the temperature characteristics of each sensor are different, so the same temperature correction methods are used for different types of sensors. It is difficult to apply the method, and there is a problem that the accuracy of temperature correction is low as the gas sensor ages.

Therefore, there is a problem with a method of correcting the reactivity of a gas sensor that responds to the aging of the MOS gas sensor and a method of correcting a gas sensor that changes depending on temperature.

The problem to be solved by the present invention relates to a gas sensor for accurately detecting gas, and is to provide a gas sensor that provides self-calibration and a gas detection method.

However, the problems to be solved by the present invention are not limited to those mentioned above, and other problems to be solved that are not mentioned can be clearly understood by those skilled in the art to which the present invention pertains from the description below. will be.

The gas concentration measurement control method of a gas sensor measurement system including a gas sensor for measuring gas concentration according to the first embodiment of the present invention includes storing a reference resistance value of the gas sensor for measuring gas concentration by the gas sensor. steps; Using the gas sensor, determining whether there is gas around the gas sensor at a first time after starting to measure the gas concentration; When it is determined that there is no gas around the gas sensor at the first time point, the method may include updating the resistance value of the gas sensor at the first time point as the reference resistance value.

The step of determining whether there is gas around the gas sensor at the first time point includes periodically measuring the resistance value of the gas sensor during a first time window from the first time point until a predetermined time ago, Including determining whether there is gas around the gas sensor based on the average value of the resistance value of the gas sensor measured within the first time window and the resistance value of the gas sensor measured at the first time point. can do.

The step of determining whether there is gas around the gas sensor at the first time point includes detecting the gas sensor through a pattern recognition algorithm for the resistance value of the gas sensor and the resistance value of the gas sensor at the first time point. It is possible to determine whether there is gas nearby.

In the gas concentration measurement control method of a gas measurement system including a gas sensor for measuring gas concentration according to the second embodiment of the present invention, the reference resistance value and gas concentration of the gas sensor for measuring gas concentration by the gas sensor obtaining coefficients; Using the gas sensor, determining whether there is gas around the gas sensor at a first time; When it is determined that there is no gas around the gas sensor at the first time point, obtaining the measured resistance value of the gas sensor at the first time point as a first resistance value and updating it as the reference resistance value; Using the gas sensor, determining whether there is gas around the gas sensor at a second time after the first time; When it is determined that there is no gas around the gas sensor at the second time point, obtaining the measured resistance value of the gas sensor at the first time point as the second resistance value and updating it as the reference resistance value. ; It may include correcting the concentration coefficient based on the first resistance value and the second resistance value.

The step of determining whether there is gas around the gas sensor at the first time point includes periodically measuring the resistance value of the gas sensor during a first time window from the first time point until a predetermined time ago, Including determining whether there is gas around the gas sensor based on the average value of the resistance value of the gas sensor measured within the first time window and the resistance value of the gas sensor measured at the first time point. can do.

The step of determining whether there is gas around the gas sensor at the first time point includes detecting the gas sensor through a pattern recognition algorithm for the resistance value of the gas sensor and the resistance value of the gas sensor at the first time point. It is possible to determine whether there is gas nearby.

The step of correcting the concentration coefficient includes determining whether a resistance value ratio of the second resistance value to the first resistance value is less than or equal to a predetermined threshold value; When the resistance value ratio is below the predetermined threshold, the step of adjusting the concentration coefficient may be included.

The step of correcting the concentration coefficient may be to reduce the concentration coefficient based on the resistance value ratio when the resistance value ratio is below the predetermined threshold.

The step of correcting the concentration coefficient may be adjusting the concentration coefficient based on a resistance value ratio of the second resistance value to the first resistance value.

The concentration at the first time point measured by the gas sensor may be determined by the reference resistance value, the concentration coefficient, and the first resistance value of the gas sensor.

A gas concentration measurement control method of a gas measurement system including a gas sensor for measuring gas concentration, a temperature sensor for measuring temperature, and a heater for adjusting the temperature of the gas sensor according to the third embodiment of the present invention includes the gas sensor storing the reference temperature of the gas sensor for measuring gas concentration by; measuring the temperature of the gas sensor at a first time after starting to measure the gas concentration; and adjusting the temperature of the gas sensor by adjusting the voltage of the heater based on the reference temperature and the temperature of the gas sensor measured at the first time point.

The step of adjusting the temperature of the gas sensor includes increasing the voltage of the heater when the temperature of the gas sensor measured at the first time point is higher than the reference temperature, and increasing the temperature of the gas sensor measured at the first time point. If is lower than the reference temperature, the voltage of the heater may be reduced.

The step of storing the reference temperature of the gas sensor includes measuring the temperature of the gas sensor, storing the reference temperature based on the resistance value of the temperature sensor, and measuring the temperature of the gas sensor at the first time point. The step may be measuring the temperature of the gas sensor measured at the first time point based on the resistance value of the temperature sensor measured at the first time point.

A gas concentration measurement control device according to a fourth embodiment of the present invention includes a gas sensor that measures gas concentration; and a processor that controls the gas sensor, wherein the processor stores a reference resistance value of the gas sensor for measuring gas concentration by the gas sensor, and starts measuring the gas concentration using the gas sensor. Determine whether there is gas around the gas sensor at a subsequent first time point, and if it is determined that there is no gas around the gas sensor at the first time point, the resistance value of the gas sensor at the first time point can be updated as the reference resistance value.
The computer program stored in the computer-readable recording medium according to the fifth embodiment of the present invention, when executed by the processor, determines the reference resistance value and gas concentration coefficient of the gas sensor for measuring gas concentration by the gas sensor. acquiring; Using the gas sensor, determining whether there is gas around the gas sensor at a first time; When it is determined that there is no gas around the gas sensor at the first time point, obtaining the measured resistance value of the gas sensor at the first time point as a first resistance value and updating it as the reference resistance value; Using the gas sensor, determining whether there is gas around the gas sensor at a second time after the first time; When it is determined that there is no gas around the gas sensor at the second time point, obtaining the measured resistance value of the gas sensor at the first time point as the second resistance value and updating it as the reference resistance value. ; It may include instructions for causing the processor to perform a method including correcting the concentration coefficient based on the first resistance value and the second resistance value.
A computer-readable recording medium storing a computer program according to a sixth embodiment of the present invention, when instructions included in the computer program are executed by a processor, the gas sensor for measuring gas concentration by the gas sensor Obtaining a reference resistance value and gas concentration coefficient; Using the gas sensor, determining whether there is gas around the gas sensor at a first time; When it is determined that there is no gas around the gas sensor at the first time point, obtaining the measured resistance value of the gas sensor at the first time point as a first resistance value and updating it as the reference resistance value; Using the gas sensor, determining whether there is gas around the gas sensor at a second time point after the first time point; When it is determined that there is no gas around the gas sensor at the second time point, obtaining the measured resistance value of the gas sensor at the first time point as the second resistance value and updating it as the reference resistance value. ; It may include a computer program including instructions for causing the processor to perform a method including correcting the concentration coefficient based on the first resistance value and the second resistance value.

According to an embodiment of the present invention, by measuring the gas sensor resistance value and correcting the resistance value and gas concentration coefficient of the gas sensor, accurate gas concentration detection is possible even as aging progresses over time, and the temperature of the gas sensor is maintained. Since the resistance value of the gas sensor can be kept constant, the gas concentration can be accurately detected even due to changes in external temperature.

1 is a block diagram showing a gas sensor calibration system according to an embodiment of the present invention.
Figure 2 is a block diagram conceptually showing the function of a gas sensor concentration correction program according to an embodiment of the present invention.
Figure 3 is a graph showing the slope of the gas sensor resistance value according to the degree of aging when there is no gas in the gas sensor.
Figure 4 is a graph showing the correlation between gas concentration and gas reactivity for each gas sensor sample.
Figure 5 is a graph showing the results of a method for determining that gas does not exist according to an embodiment of the present invention.
Figure 6 shows a temperature compensation system according to an embodiment of the present invention.
Figure 7 is a graph showing gas reactivity according to a temperature compensation method compared to external temperature change according to an embodiment of the present invention.
Figure 8 is a flowchart showing a method for a gas sensor calibration device to calibrate a gas sensor according to an embodiment of the present invention.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The present embodiments are merely provided to ensure that the disclosure of the present invention is complete and to be understood by those skilled in the art. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

In describing embodiments of the present invention, if a detailed description of a known function or configuration is judged to unnecessarily obscure the gist of the present invention, the detailed description will be omitted. The terms described below are terms defined in consideration of functions in the embodiments of the present invention, and may vary depending on the intention or custom of the user or operator. Therefore, the definition should be made based on the contents throughout this specification.

1 is a block diagram showing a gas sensor calibration system according to an embodiment of the present invention.

Referring to FIG. 1, the gas measurement system 10 may include a gas sensor 20, a temperature sensor 30, and a gas concentration measurement control device 100.

In this specification, for convenience of explanation, the gas concentration measurement control device 100 is described as a separate device from the gas sensor 20 and the temperature sensor 30, but is not limited thereto. That is, depending on the embodiment, the gas sensor 20 and the temperature sensor 30 may be included in the gas concentration measurement control device 100.

The gas sensor 20 may include a heater that controls the temperature of the gas sensor 20, and the heater and the gas sensor 20 may be separated into separate devices.

In the present invention, the gas sensor 20 is a MOS type gas sensor among semiconductor gas sensors. Semiconductor gas sensors exist in bulk type, thick film type, thin film type, and MOS type. MOS-type gas sensors are widely used as they can detect almost all types of gases, including CO, hydrogen gas, nitrogen dioxide, and methane gas.

The gas sensor 20 detects gas by using the change in resistance of the gas sensor 20 when combustible gas, reducible gas, organic solvent gas, water vapor, etc. react. Here, the degree to which the resistance of the gas sensor 20 changes may vary depending on the sensor's operating temperature, humidity, usage time, etc.

The gas sensor 20 may define gas reactivity as the ratio of the change in Ro, which is the resistance value of the gas sensor 20 when there is no gas, and Rs or Rs, which is the current resistance value of the gas sensor. The gas measurement system 10 can measure the current gas concentration using gas reactivity.

In general, the method of measuring gas concentration with a gas sensor is to set the resistance value of the gas sensor initially measured in the absence of gas as Ro, and then use the initially measured fixed Ro value and the current resistance value of the gas sensor, Rs. The gas concentration is measured by the gas reactivity calculated using the value.

The temperature sensor 30 may include a heater and may include a resistance of the temperature sensor 30 therein. The resistance of the temperature sensor 30 is affected by external temperature, so the resistance value of the temperature sensor 30 may change depending on the influence of the external temperature.

Additionally, the heater may increase or decrease the temperature of the gas sensor 20 and the temperature sensor 30 according to the input voltage value received from the processor 110.

The gas concentration measurement control device 100 may include a processor 110, a GAS ROIC (GAS Read Out Integrated Circuit, 120), a temperature maintenance circuit 130, and a memory 140.

For convenience of explanation, the processor 110 is described as a separate device from the GAS ROIC 120, but the present invention is not limited thereto. That is, depending on the embodiment, the GAS ROIC 120 may be included in the processor 110.

The processor 110 may perform overall control of the gas concentration measurement control device 100.

For overall control, the processor 110 can receive the resistance values of the gas sensor 20 and the temperature sensor 30 converted into digital signals from the GAS ROIC 120, and maintain the temperature from the GAS ROIC 120. The voltage value of the heater output from the circuit 130 can be converted into a digital signal.

More specifically, the processor 110 may control the temperature maintenance circuit 130 by receiving the resistance value of the temperature sensor 30 from the temperature sensor 30, and receive a voltage value corresponding to the voltage value from the temperature maintenance circuit 130. By receiving the values, the voltage of the gas sensor 20 and the temperature sensor 30 heater can be controlled. Accordingly, the processor 110 can adjust the temperatures of the gas sensor 20 and the temperature sensor 30.

Additionally, the processor 110 may determine the gas concentration of the gas sensor using the gas sensor concentration correction program 200 from the memory 140 and the resistance value of the gas sensor 20 received from the gas sensor 20.

The GAS ROIC 120 is controlled by the processor 110 and can adjust the heater voltage of the gas sensor 20 and the temperature sensor 30 using a digital signal, and can adjust the heater voltage of the gas sensor 20 from the gas sensor 20. The resistance value can be input, converted into a digital signal, and transmitted to the processor 110.

The temperature maintenance circuit 130 may be a circuit that can determine a voltage to keep the voltage value of the heater constant using the resistance value of the temperature sensor 30. The temperature maintenance circuit 130 can minimize the influence of external temperature changes on gas reactivity by maintaining the temperature of the gas sensor 20 and the temperature sensor 20 constant. In other words, the temperature maintenance circuit 130 allows the accurate amount of gas to be detected even when the external temperature changes. The detailed operation of the temperature maintenance circuit 130 will be described later with reference to FIG. 6.

The memory 140 may store the gas sensor concentration correction program 200 and information necessary for execution of the gas sensor concentration correction program 200.

In this specification, the gas sensor concentration correction program 200 may refer to a program that corrects the gas sensor concentration using the resistance value of the gas sensor 20 or software that includes instructions programmed to correct the gas sensor concentration.

The function and/or operation of the gas sensor concentration correction program 200 will be examined in detail with reference to FIG. 2.

Figure 2 is a block diagram conceptually showing the function of a gas sensor concentration correction program according to an embodiment of the present invention.

Referring to FIG. 2, the gas sensor concentration correction program 200 may include a concentration coefficient correction unit 210, a Ro correction unit 220, and a gas presence confirmation unit 230.

The concentration coefficient correction unit 210 may correct the gas concentration coefficient based on the slope representing the change in Ro value over time.

Figure 3 is a graph showing the slope of the gas sensor resistance according to the degree of aging when there is no gas in the gas sensor.

Referring to FIG. 3, first, in the gas sensor, the value corresponding to the log scale of the resistance value of the gas sensor decreases linearly with the passage of time (T) shown on the x-axis of the graph. You can check it. In addition, when comparing the slope (Slope A) over time of A (Aged), which is the resistance of a non-aged gas sensor, and the slope (Slope B) over time of O (Original), which is the resistance of an aged gas sensor, it can be seen that aging It can be seen that the absolute value of the slope over time of A, which is the resistance of the gas sensor, is smaller than the slope of O at the same time (T1).

In other words, as the aging of the gas sensor progresses, the absolute value of the slope of the resistance Ro of the gas sensor increases, so the slope of the resistance Ro of the gas sensor can be considered to indicate the degree of aging of the gas sensor. Therefore, if the slope of Ro is known, the concentration coefficient of the gas sensor according to the aging of the gas sensor can be corrected.

Figure 4 is a graph showing the correlation between gas concentration and gas reactivity for each gas sensor sample.

Referring further to FIG. 4, the correlation between the log scale value of gas concentration (X-axis in FIG. 4) and gas reactivity (Y-axis in FIG. 4) is obtained from samples of various gas sensors (Sample 1 to Sample 4). Regardless, there is a linear relationship. Therefore, the concentration coefficient correction unit 210 measures gas reactivity using the linear relationship between the log scale value of gas concentration (X-axis in FIG. 4) and gas reactivity (Y-axis in FIG. 4). Gas concentration can be detected.

More specifically, the correlation between the log scale value of gas concentration and gas reactivity has the relationship shown in Equation 1 below, so gas concentration can be measured using this.

Here, Rs/Ro represents gas reactivity, gas concentration represents the current gas concentration, and S represents the gas concentration coefficient.

The correlation between the Ro slope and the gas concentration coefficient is as shown in Table 1 below, which is data measuring the Ro slope and the gas concentration coefficient according to a plurality of gas sensor samples (Sample 1 to Sample 4). Accordingly, the concentration coefficient correction unit 210 can correct the concentration coefficient using this correlation, thereby detecting an accurate amount of gas even when the gas sensor is aged.

Sample 1 Sample 2 Sample 3 Sample 4 Ro tilt -4.522e-4 -7.443e-4 -8.954e-4 -8.403e-4 gas concentration coefficient -0.1921 -0.2012 -0.2037 -0.1972

In other words, referring to Table 1 and FIG. 4, the concentration coefficient correction unit 210 can calculate the correlation between the Ro slope and the concentration coefficient through various gas sensor samples, and use this correlation to correct the concentration coefficient. You can.

According to an embodiment of the present invention, the concentration coefficient correction unit 210 determines the first resistance value of the gas sensor when it is determined that there is no gas at the first time point and the gas sensor's first resistance value when it is determined that there is no gas at a second time point after the first time point. In this case, it can be determined whether the ratio of the second resistance value of the gas sensor is below a predetermined threshold. Subsequently, when the resistance value ratio falls below a predetermined threshold, the concentration coefficient correction unit 210 reduces the concentration coefficient based on the resistance value ratio to measure an accurate gas concentration.

In addition, the concentration coefficient correction unit 210 may adjust the concentration coefficient value based on the ratio of the first resistance value and the second resistance value without determining whether the first resistance value and the second resistance value are measured or less than the threshold value. there is.

Therefore, according to an embodiment of the present invention, even if the gas sensor of the concentration coefficient correction unit 210 ages over time, the concentration coefficient can be corrected to detect an accurate amount of gas.

Referring again to FIGS. 1 and 2, according to an embodiment of the present invention, the Ro correction unit 220 may correct the Ro value when it is determined that there is no gas.

According to another embodiment of the present invention, the Ro correction unit 220 does not determine gas reactivity using the Ro value, which is an initially measured and fixed reference resistance value like a general gas sensor, but determines that there is currently no gas. In this case, by measuring the resistance value of the gas sensor 20 and correcting it by updating it with the Ro value, accurate current gas reactivity can be measured.

However, in order to measure the resistance value Ro of the gas sensor 20 when the Ro correction unit 220 determines that there is currently no gas, it is necessary to confirm the presence of gas.

Figure 5 is a graph showing the results of a method for determining that gas does not exist according to an embodiment of the present invention.

Referring to FIGS. 1, 2, and 5, according to an embodiment of the present invention, the gas presence confirmation unit 230 may determine whether gas exists. The dotted line in the graph represents the actual amount of gas over time as gas reactivity. In addition, the solid line in the graph represents the result of the gas presence confirmation unit 230 determining that gas exists over time, and when the gas presence confirmation unit 230 determines that gas does not exist, it outputs 0 as a result value, If it is determined that gas exists, 1 can be output as the result.

Referring to the graph (a) of FIG. 5, the gas presence confirmation unit 230 currently measures the resistance value of the gas sensor 20, calculates the average value of the resistance value during a predetermined window measured before, and calculates the calculated resistance. The average value can be compared with the current resistance value of the gas sensor 20. Since the resistance value of the gas sensor 20 has different values depending on the presence or absence of gas, if the resistance value of the gas sensor 20 changes rapidly compared to the previously measured average resistance value, it can be determined that gas is present. .

Therefore, the gas presence confirmation unit 230 determines whether the gas exists by the first confirmation method of determining whether the difference between the current resistance value of the gas sensor 20 and the average value of the previously measured resistance values is within a predetermined range. You can judge that it does.

Subsequently, when the gas presence confirmation unit 230 determines that gas does not exist, the Ro correction unit 220 may update the currently measured resistance value of the gas sensor 20 to Ro.

Referring to graph (b) of FIG. 5, according to an embodiment of the present invention, the gas presence confirmation unit 230 performs machine learning such as pattern recognition using an artificial neural network (ANN) to determine if the gas is present. You can determine whether it exists or not.

The pattern recognition machine learning method according to an embodiment of the present invention can learn by receiving the type of gas and the presence or absence of gas as learning data and using the correct answer data about the type of gas and the presence or absence of the actual gas. there is.

In the graph (b) of FIG. 5, the solid line outputs 0 as the result value when the gas presence confirmation unit 230 determines that gas does not exist using an artificial neural network, and outputs 1 as the result value when it determines that gas exists. It can be output as . That is, the gas presence confirmation unit 230 may determine that gas exists using a second confirmation method that determines the presence of gas using pattern recognition machine learning.

Subsequently, when the gas presence confirmation unit 230 determines that gas does not exist, the Ro correction unit 220 may update the measured resistance value of the gas sensor 20 to Ro.

Referring to the graph (a) of Figures 2 and 5, the graph (b) of Figure 5, and the graph (c) of Figure 5, according to an embodiment of the present invention, the gas presence confirmation unit 230 is a current gas sensor. If the average value of the resistance value of (20) and the resistance value of the previous gas sensor 20 is within a predetermined range and it is determined that gas does not exist using an artificial neural network, the result value can be output as 0.

That is, if the gas presence confirmation unit 230 determines that gas does not exist in both the first confirmation method and the second confirmation method, it can finally determine that gas does not exist.

Subsequently, when the gas presence confirmation unit 230 determines that gas does not exist, the Ro correction unit 220 may update the measured resistance value of the gas sensor 20 to Ro.

Referring further to FIG. 1, according to an embodiment of the present invention, the gas presence confirmation unit 230 satisfies both the first confirmation method and the second confirmation method in order to more accurately determine if gas does not exist. The Ro value can only be updated. Accordingly, the gas sensor calibration device 100 can obtain more accurate gas reactivity and detect accurate gas concentration even when the gas sensor 20 is aged.

Hereinafter, Figures 6 and 7 explain the method and results of maintaining the temperature to keep the reactivity of the gas sensor constant, according to another embodiment of the present invention.

Figure 6 shows a temperature compensation system according to another embodiment of the present invention. However, the temperature maintenance circuit 130 is only an example implemented according to another embodiment of the present invention, and may be implemented in other ways. That is, the temperature of the gas sensor can be measured from the outside and the temperature of the gas sensor can be maintained using a heater based on the measured temperature, or the temperature of the gas sensor can be measured internally in addition to the temperature maintenance circuit 130 and the measured temperature can be maintained. The temperature of the gas sensor can also be maintained using a heater based on the temperature.

Referring to FIG. 6, the temperature compensation system 60 may include a gas sensor 20, a temperature sensor 30, a GAS ROIC 120, a processor 110, and a temperature maintenance circuit 130.

The resistance value Rt of the temperature sensor 30 can be affected by the external temperature, and this influence appears through the current Rt value. Therefore, by comparing the initial Rt value and the current Rt value, it can be seen that the external temperature has changed. there is. Therefore, the temperature can be corrected to the initial value by measuring the current Rt value and using feedback on the Rt value.

According to one embodiment of the present invention, the processor 110 may be an MCU (Micro Controller Unit). In addition, the processor 110 can input the resistance value Rt of the temperature sensor from the temperature sensor 30 to the temperature maintenance circuit 130, and the gas sensor 20 and the temperature sensor 30, which are output values of the temperature maintenance circuit 130. ) of the heater voltage value Vh can be input to the heater of the gas sensor 20 and the temperature sensor 30.

The GAS ROIC 120 may include a digital signal conversion unit 64 and a heater voltage control unit 66. The digital signal converter 64 may receive the resistance value of the gas sensor 20 or the temperature sensor 30 and convert it into a digital signal. The heater voltage control unit 66 receives control from the processor 110 and can adjust the heater voltage of the gas sensor 20 and the temperature sensor 30.

First, the GAS ROIC 120 can receive a digital signal by converting the initial resistance value Rt of the temperature sensor 30 into a digital signal. Subsequently, the processor 110 may receive the current resistance value Rt of the temperature sensor 30 through the GAS ROIC 120, compare the current resistance value Rt and the initial resistance value Rt, and output it to the temperature maintenance circuit 130. there is.

The temperature maintenance circuit 130 may include a current DAC (Digital to Analog Converter), a counter, an R-2R DAC, an OP-Amp (Operational Amplifier), and a plurality of resistors.

The R-2R DAC of the temperature maintenance circuit 130 may compare the initial resistance value Rt and the current resistance value Rt and output the compared value as a voltage. Subsequently, the temperature maintenance circuit 130 can use the output voltage value as the input value of the OP-Amp, convert the output value of the OP-Amp into a digital signal by passing it through a counter and a current DAC, and input it to the processor 110. You can.

The processor 110 may input temperature information received from the temperature maintenance circuit 130 into the GAS ROIC (120).

Subsequently, the heater voltage control unit 32 of the GAS ROIC 120 uses the input temperature information to increase or decrease the heater voltage value Vh of the gas sensor 20 and the temperature sensor 30 to increase or decrease the heater voltage value Vh of the gas sensor 20 and the temperature sensor 30. Since the temperature of the sensor 30 can be adjusted, the temperature of the gas sensor 20 and the temperature sensor 30 can be maintained constant despite changes in external temperature.

Figure 7 is a graph showing gas reactivity according to a temperature compensation method compared to external temperature change according to an embodiment of the present invention.

Referring to Figures 6 and 7, the change in resistance value of the gas sensor 20 can be seen compared to the change in external temperature. According to one embodiment of the present invention, when the temperature maintenance circuit 130 is used (Constant Temperature) compared to when the heater voltage is kept constant (Constant heater Voltage) and when the power to the heater is kept constant (Constant heater Power) It can be confirmed that the resistance value (Normalized Ro) of the gas sensor 20 remains constant despite changes in external temperature.

Therefore, according to an embodiment of the present invention, constant gas reactivity can be maintained despite changes in external temperature, so the temperature compensation system 60 can accurately detect gas concentration despite changes in external temperature.

Figure 8 is a flowchart showing a method of controlling gas concentration measurement by a gas concentration measurement control device according to an embodiment of the present invention.

Referring to FIGS. 1 and 8 , the processor 110 may first confirm the presence or absence of gas by comparing the average resistance value of the gas sensor 20 with the current resistance value of the gas sensor 20 (S80).

Next, the processor 110 can check the presence or absence of gas using an artificial neural network learned through pattern recognition (S82).

The processor 110 determines that there is no gas by comparing the average resistance value of the gas sensor 20 with the current resistance value of the gas sensor 20, and when it determines that there is no gas using an artificial neural network, the gas sensor 20 When there is no gas, the resistance value Ro can be corrected to the current resistance value of the gas sensor 20 (S84).

Subsequently, the processor 110 may correct the gas concentration coefficient using the corrected resistance value of the gas sensor 20 (S86).

The processor 110 may measure the gas concentration using the corrected gas reactivity and the corrected gas concentration coefficient obtained by measuring the resistance value of the gas sensor 20 (S88).

Unlike existing gas sensor calibration methods, the present invention does not require a lot of time and cost and can accurately measure gas concentration even when the gas sensor ages and changes in external temperature, so it can be used as a core function to improve the performance of various systems.

Combinations of each block of the block diagram and each step of the flow diagram attached to the present invention may be performed by computer program instructions. Since these computer program instructions can be mounted on the encoding processor of a general-purpose computer, special-purpose computer, or other programmable data processing equipment, the instructions performed through the encoding processor of the computer or other programmable data processing equipment are included in each block or block of the block diagram. Each step of the flowchart creates a means to perform the functions described. These computer program instructions may also be stored in computer-usable or computer-readable memory that can be directed to a computer or other programmable data processing equipment to implement a function in a particular way, so that the computer-usable or computer-readable memory The instructions stored in can also produce manufactured items containing instruction means that perform the functions described in each block of the block diagram or each step of the flow diagram. Computer program instructions can also be mounted on a computer or other programmable data processing equipment, so that a series of operational steps are performed on the computer or other programmable data processing equipment to create a process that is executed by the computer, thereby generating a process that is executed by the computer or other programmable data processing equipment. Instructions that perform processing equipment may also provide steps for executing functions described in each block of the block diagram and each step of the flow diagram.

Additionally, each block or each step may represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical function(s). Additionally, it should be noted that in some alternative embodiments it is possible for the functions mentioned in the blocks or steps to occur out of order. For example, two blocks or steps shown in succession may in fact be performed substantially simultaneously, or the blocks or steps may sometimes be performed in reverse order depending on the corresponding function.

The above description is merely an illustrative explanation of the technical idea of the present invention, and those skilled in the art will be able to make various modifications and variations without departing from the essential quality of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but are for illustrative purposes, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be interpreted in accordance with the claims below, and all technical ideas within the scope equivalent thereto shall be construed as being included in the scope of rights of the present invention.

10: Gas measurement system
20: gas sensor
30: temperature sensor
60: Temperature compensation system
100: Gas concentration measurement control device
110: processor
120: GAS ROIC
200: Gas sensor concentration correction program
210: Concentration coefficient correction unit
220: Ro correction unit
230: Gas presence confirmation unit

Claims (16)

In the gas concentration measurement control method of a gas measurement system including a gas sensor for measuring gas concentration,
Obtaining a reference resistance value and a gas concentration coefficient of the gas sensor for measuring gas concentration by the gas sensor;
Using the gas sensor, determining whether there is gas around the gas sensor at a first time;
When it is determined that there is no gas around the gas sensor at the first time point, obtaining the measured resistance value of the gas sensor at the first time point as a first resistance value and updating it as the reference resistance value;
Using the gas sensor, determining whether there is gas around the gas sensor at a second time after the first time;
When it is determined that there is no gas around the gas sensor at the second time point, obtaining the measured resistance value of the gas sensor at the first time point as the second resistance value and updating it as the reference resistance value. ; and
Comprising the step of correcting the concentration coefficient based on the rate of change of the reference resistance value,
Gas concentration measurement control method. According to claim 1,
The step of determining whether there is gas around the gas sensor at the first time point is,
periodically measuring the resistance value of the gas sensor during a first time window from the first time point to a predetermined time period;
Including determining whether there is gas around the gas sensor based on the average value of the resistance value of the gas sensor measured within the first time window and the resistance value of the gas sensor measured at the first time point. doing,
Gas concentration measurement control method. According to claim 1,
The step of determining whether there is gas around the gas sensor at the first time point is,
Determining whether there is gas around the gas sensor through a pattern recognition algorithm for the resistance value of the gas sensor and the resistance value of the gas sensor at the first time point.
Gas concentration measurement control method. delete delete delete According to claim 1,
The step of correcting the concentration coefficient is,
determining whether a resistance value ratio of the second resistance value to the first resistance value is less than or equal to a predetermined threshold value;
When the resistance value ratio is below the predetermined threshold, adjusting the concentration coefficient.
Gas concentration measurement control method. According to claim 7,
The step of correcting the concentration coefficient is,
When the resistance value ratio is below the predetermined threshold, the concentration coefficient is reduced based on the resistance value ratio.
Gas concentration measurement control method. According to claim 1,
The step of correcting the concentration coefficient is,
Adjusting the concentration coefficient based on the resistance value ratio of the second resistance value to the first resistance value.
Gas concentration measurement control method. According to claim 1,
The concentration at the first time point measured by the gas sensor is,
Determined by the reference resistance value, the concentration coefficient, and the first resistance value of the gas sensor
Gas concentration measurement control method. In the gas concentration measurement control method of a gas measurement system including a gas sensor for measuring gas concentration, a temperature sensor for measuring temperature, and a heater for adjusting the temperature of the gas sensor,
Obtaining a reference resistance value and a gas concentration coefficient of the gas sensor for measuring gas concentration by the gas sensor;
Using the gas sensor, determining whether there is gas around the gas sensor at a first time;
When it is determined that there is no gas around the gas sensor at the first time point, obtaining the measured resistance value of the gas sensor at the first time point as a first resistance value and updating it as the reference resistance value;
Using the gas sensor, determining whether there is gas around the gas sensor at a second time after the first time;
When it is determined that there is no gas around the gas sensor at the second time point, obtaining the measured resistance value of the gas sensor at the first time point as the second resistance value and updating it as the reference resistance value. ;
correcting the concentration coefficient based on the rate of change of the reference resistance value;
storing a reference temperature of the gas sensor for measuring gas concentration by the gas sensor;
measuring the temperature of the gas sensor at a first time after starting to measure the gas concentration; and
Comprising adjusting the temperature of the gas sensor by adjusting the voltage of the heater based on the reference temperature and the temperature of the gas sensor measured at the first time point.
Gas concentration measurement control method. According to claim 11,
The step of adjusting the temperature of the gas sensor is
If the temperature of the gas sensor measured at the first time is higher than the reference temperature, the voltage of the heater is increased, and if the temperature of the gas sensor measured at the first time is lower than the reference temperature, the heater which reduces the voltage of
Gas concentration measurement control method. According to claim 11,
The step of storing the reference temperature of the gas sensor is,
Measuring the temperature of the gas sensor, the reference temperature is stored based on the resistance value of the temperature sensor.
The step of measuring the temperature of the gas sensor at the first time point is,
Measuring the temperature of the gas sensor measured at the first time point based on the resistance value of the temperature sensor measured at the first time point.
Gas concentration measurement control method. A gas sensor that measures gas concentration; and
Including a processor that controls the gas sensor,
The processor,
Obtain a reference resistance value and a gas concentration coefficient of the gas sensor for measuring gas concentration by the gas sensor, and determine whether there is gas around the gas sensor at a first time using the gas sensor, When it is determined that there is no gas around the gas sensor at the first time point, the measured resistance value of the gas sensor at the first time point is obtained as a first resistance value, updated to the reference resistance value, and the Using a gas sensor, it is determined whether there is gas around the gas sensor at a second time point after the first time point, and if it is determined that there is no gas around the gas sensor at the second time point, the first time point is determined. Obtaining the measured resistance value of the gas sensor at a point in time as the second resistance value, updating it as the reference resistance value, and correcting the concentration coefficient based on the change rate of the reference resistance value,
Gas concentration measurement control device. A computer-readable recording medium storing a computer program,
The computer program is,
Comprising instructions for causing a processor to perform the method according to any one of claims 1 to 3 and 7 to 13.
A computer-readable recording medium. A computer program stored on a computer-readable recording medium,
The computer program is,
Comprising instructions for causing a processor to perform the method according to any one of claims 1 to 3 and 7 to 13.
A computer program stored on a computer-readable recording medium.

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