An automatic calibration method for a three-electrode oxygen probe

Abstract

The present application relates to gas detection analysis technical field, especially to a kind of three-electrode oxygen probe's automatic calibration method.Content includes: construct closed calibration box, and the output voltage of standard oxygen concentration and the probe to be calibrated is synchronously collected;Based on standard oxygen concentration variation, construct atmosphere evolution state quantity, combine the output voltage of the probe to be calibrated, calculate electrode response trajectory quantity;Atmosphere evolution state quantity and electrode response trajectory quantity are fused, and relative response characteristic quantity is constructed, combined with the nonlinear response of the probe to be calibrated in different oxygen concentration range and zero drift, dynamic calibration model is constructed, and the oxygen concentration output result after calibration is obtained, and the parameter in dynamic calibration model is iterated and updated, and calibration parameter is obtained.The three-electrode oxygen probe calibration method does not consider gas dynamic diffusion and probe response delay, and lacks effective compensation for nonlinearity and zero drift, which leads to insufficient detection accuracy.

Description

Technical Field

[0001] This invention relates to the field of gas detection and analysis technology, and in particular to an automated calibration method for a three-electrode oxygen probe. Background Technology

[0002] Oxygen concentration, as a crucial parameter reflecting environmental conditions, industrial process safety, and equipment operational reliability, is widely used in industrial production, environmental monitoring, medical equipment, and gas analysis instruments. Three-electrode oxygen probes utilize the electrochemical reaction between the working electrode, counter electrode, and reference electrode to detect oxygen concentration. They feature fast response, high sensitivity, compact structure, and suitability for continuous monitoring, making them invaluable in high-precision oxygen detection scenarios. As oxygen detection environments become increasingly complex, probes need to maintain stable detection capabilities under varying oxygen concentrations and gas states. Therefore, effective calibration methods are necessary to correct probe readings and ensure they meet practical application requirements.

[0003] However, the calibration method for three-electrode oxygen probes typically acquires the probe's output signal under a fixed oxygen concentration environment and achieves calibration by establishing a correspondence between oxygen concentration and output voltage. This method does not fully consider the impact of gas diffusion and mixing during the standard gas input process, as well as the dynamic changes in oxygen concentration in the detection area, on the calibration results. This leads to a deviation between the calibration environment and the actual response state of the probe. At the same time, it usually ignores the response hysteresis caused by the internal electrode reaction, oxygen molecule diffusion, and electrical signal conversion process of the three-electrode oxygen probe, making it difficult for the calibration model to accurately reflect the dynamic detection characteristics of the probe. In addition, traditional calibration methods lack effective compensation for nonlinear responses in different oxygen concentration ranges, zero-point drift caused by long-term use, and individual differences in probes. This results in insufficient accuracy of oxygen concentration detection results and poor environmental adaptability, making it difficult to meet the requirements of high-precision oxygen detection. Summary of the Invention

[0004] This invention provides an automated calibration method for a three-electrode oxygen probe. This addresses the problems of traditional three-electrode oxygen probe calibration methods, which typically acquire probe output signals under fixed oxygen concentration conditions and establish a correlation between oxygen concentration and output voltage. These methods fail to adequately consider the impact of gas diffusion and mixing during standard gas input, as well as the dynamic changes in oxygen concentration in the detection area, on the calibration results. This leads to discrepancies between the calibration environment and the actual probe response. Furthermore, traditional calibration methods often neglect response hysteresis caused by internal electrode reactions, oxygen molecule diffusion, and electrical signal conversion processes within the three-electrode oxygen probe, making it difficult for the calibration model to accurately reflect the probe's dynamic detection characteristics. Additionally, traditional calibration methods lack effective compensation for nonlinear responses across different oxygen concentration ranges, zero-point drift from long-term use, and individual probe variations, resulting in insufficient accuracy and poor environmental adaptability in oxygen concentration detection, failing to meet the demands of high-precision oxygen detection.

[0005] An automated calibration method for a three-electrode oxygen probe according to the present invention specifically includes the following steps: S1. Construct a sealed calibration chamber and simultaneously collect the standard oxygen concentration and the output voltage of the three-electrode oxygen probe to be calibrated; analyze the gas replacement process and construct the atmosphere evolution state quantity based on the change of standard oxygen concentration; calculate the electrode response trajectory quantity based on the atmosphere evolution state quantity and the output voltage of the three-electrode oxygen probe to be calibrated. S2. The atmosphere evolution state quantity and the electrode response trajectory quantity are fused to construct a relative response characteristic quantity. Combined with the nonlinear response and zero-point drift of the three-electrode oxygen probe to be calibrated in different oxygen concentration ranges, a dynamic calibration model is constructed to obtain the calibrated oxygen concentration output result. Based on the calibrated oxygen concentration output result, the parameters in the dynamic calibration model are iteratively updated to obtain the calibration parameters.

[0006] Preferably, S1 specifically includes: Based on the standard oxygen concentration, the change in standard oxygen concentration between the current sampling time and the previous sampling time is calculated. Combined with the standard oxygen concentration at the previous sampling time, the atmosphere evolution state is constructed. The specific formula is as follows: , in, Indicates the first Atmosphere evolution state quantity corresponding to each sampling time; Indicates the first The standard oxygen concentration corresponding to each sampling time; Indicates the first Standard oxygen concentration at each sampling time; To prevent extremely small positive numbers with a denominator of zero.

[0007] Preferably, S1 specifically includes: A response window is introduced. Based on the atmosphere evolution state variables and the output voltage of the three-electrode oxygen probe to be calibrated, the state changes before and after the response window are calculated. Electrode output response change terms and effective atmosphere change terms are constructed, and the electrode response trajectory is calculated. The specific formula is as follows: , in, Indicates the first The electrode response trajectory of the three-electrode oxygen probe to be calibrated at each sampling time; Indicates the first The output voltage of the three-electrode oxygen probe to be calibrated at each sampling time; This represents the change in electrode output response; Indicates the first Atmosphere evolution state quantity corresponding to each sampling time; Indicates the effective atmosphere change term; Indicates the first The output voltage of the three-electrode oxygen probe to be calibrated at each sampling time.

[0008] Preferably, S2 specifically includes: Introducing a historical baseline value for the electrode response trajectory, the deviation of the current sampling moment's electrode response trajectory value from its historical baseline value is calculated and converted into an equivalent oxygen concentration correction. This equivalent oxygen concentration correction is then added to the atmosphere evolution state value to obtain the relative response characteristic value, as shown in the following formula: , in, Indicates the first The relative response characteristics at each sampling time; Indicates the first Atmosphere evolution state quantity corresponding to each sampling time; Indicates the first The electrode response trajectory of the three-electrode oxygen probe to be calibrated at each sampling time; Historical baseline values ​​representing the electrode response trajectory of the three-electrode oxygen probe to be calibrated; This indicates the difference between the maximum and minimum standard oxygen concentrations used in this calibration. Indicates the first The relative response deviation of the three-electrode oxygen probe to be calibrated at each sampling time; To prevent extremely small positive numbers with a denominator of zero.

[0009] Preferably, S2 specifically includes: In the process of constructing the dynamic calibration model, effective calibration points are selected, and the global average value of the relative response characteristics corresponding to all effective calibration points is calculated.

[0010] Preferably, S2 specifically includes: The deviations of the relative response characteristic quantity at the current sampling time from the zero-point response characteristic and the global average value of the relative response characteristic quantity are calculated respectively. A response scale benchmark quantity is introduced for correction, resulting in the baseline oxygen concentration change constrained by the response scale. Then, a dynamic proportional correction factor is used to compensate for the nonlinear response and zero-point drift of the three-electrode oxygen probe to be calibrated, constructing a dynamic calibration model to obtain the calibrated oxygen concentration output. The specific formula is as follows: , in, Indicates the first The calibrated oxygen concentration output at each sampling time; Indicates the reference quantity of the response scale; This represents the global average value of the relative response characteristic. Indicates zero-point concentration; Indicates the zero-point response characteristics; Indicates the dynamic scaling correction factor; This represents the change in baseline oxygen concentration after being constrained by the response scale.

[0011] Preferably, S2 specifically includes: Before calibration begins, pure nitrogen gas is introduced into the calibration chamber. After the oxygen concentration drops below the preset zero oxygen threshold and stabilizes, the standard oxygen concentration value is recorded as the zero-point concentration. At the same time, the output voltage of the three-electrode oxygen probe to be calibrated is acquired, and the relative response characteristic of the three-electrode oxygen probe to be calibrated under this state is calculated as the zero-point response characteristic according to the aforementioned steps.

[0012] Preferably, S2 specifically includes: The difference between the calibrated oxygen concentration output and the standard oxygen concentration measured by the standard oxygen probe in the calibration chamber at the same sampling time is calculated to obtain the detection deviation. Based on the detection deviation, the dynamic calibration model is iteratively updated to obtain the calibration parameters corresponding to the three-electrode oxygen probe to be calibrated.

[0013] The beneficial effects of the technical solution of the present invention are: (1) In the calibration process, the present invention does not directly use the standard oxygen concentration as the basis for probe response analysis. Instead, it combines the concentration change process of the standard gas after it enters the calibration space to construct an atmosphere evolution state that can reflect the gas diffusion, mixing and homogenization process. This allows the calibration process to consider the influence of the gas environment formation process on the probe detection results and avoids calibration errors caused by insufficient gas replacement or asynchronous concentration changes in the detection area.

[0014] (2) By analyzing the change process of the output signal of the three-electrode oxygen probe within the response time range, this invention establishes an electrode response trajectory that can reflect the actual response capability of the electrode, so that the calibration process not only considers the change of external oxygen concentration, but also reflects the response hysteresis caused by oxygen molecule diffusion, electrode reaction and electrical signal conversion process, thereby improving the ability to describe the dynamic detection characteristics of the three-electrode oxygen probe.

[0015] (3) This invention integrates the gas environment state with the probe’s own response state to form a unified relative response characteristic quantity, so that the data collected under different oxygen concentration conditions can be converted to the same response description space. This avoids the problem of insufficient adaptability to environmental changes caused by establishing a calibration relationship based on a single output voltage in traditional methods, and improves the adaptability of the calibration model to different detection states.

[0016] (4) In view of the non-ideal characteristics of the three-electrode oxygen probe in actual operation, such as the approximately linear response in the low concentration area, the diffusion limitation in the high concentration area, and the zero drift during long-term use, the present invention establishes a dynamic calibration model based on the change of response state, so that the calibration results can simultaneously correct the initial zero deviation, the difference in response change, and the nonlinear error in different concentration ranges, thereby improving the accuracy of oxygen concentration detection results. Attached Figure Description

[0017] Figure 1 This is a flowchart of an automated calibration method for a three-electrode oxygen probe according to the present invention. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] The following description, in conjunction with the accompanying drawings, details the specific scheme of the automated calibration method for a three-electrode oxygen probe provided by the present invention.

[0021] See attached document Figure 1 The diagram illustrates an automated calibration method for a three-electrode oxygen probe according to an embodiment of the present invention. The method includes the following steps: S1. Construct a sealed calibration chamber and simultaneously collect the standard oxygen concentration and the output voltage of the three-electrode oxygen probe to be calibrated; analyze the gas replacement process and construct the atmosphere evolution state quantity based on the change of standard oxygen concentration; calculate the electrode response trajectory quantity based on the atmosphere evolution state quantity and the output voltage of the three-electrode oxygen probe to be calibrated. In practice, a sealed calibration chamber is constructed, comprising the chamber body, a sealing cover, a standard gas input pipeline, an extraction pipeline, a pressure balancing pipeline, a fan mixing assembly, a standard oxygen probe, and a three-electrode oxygen probe to be calibrated (hereinafter referred to as the probe to be calibrated). A sealing structure is installed between the calibration chamber cover and the chamber body, which is locked with bolts to create a stable detection space inside. The standard gas input pipeline is connected to an external standard gas cylinder, and a solenoid valve controls the entry of standard gases of different oxygen concentrations into the chamber. The extraction pipeline is connected to a vacuum pump to reduce the concentration of residual gas inside the chamber before gas replacement. The pressure balancing pipeline is used to restore the chamber pressure. The fan is used to improve the uniformity of gas inside the chamber.

[0022] Before calibration begins, install the three-electrode oxygen probe to be calibrated and the standard oxygen probe inside the calibration chamber, ensuring both are in the same gas environment. First, open the evacuation valve to reduce the internal pressure of the chamber. Then, introduce gas with a known oxygen concentration into the calibration chamber, causing a change in the internal oxygen concentration. Detect the current oxygen concentration inside the chamber using the standard oxygen probe. After the gas pressure recovers, close the inlet valve and start the fan to mix the gas inside the chamber, gradually bringing the oxygen concentration closer to uniformity.

[0023] Assume a fixed sampling period of , No. The standard oxygen concentration corresponding to each sampling time is: The unit is %, and the output voltage of the probe to be calibrated is . The unit is .in, The oxygen was obtained from the standard oxygen probe inside the calibration chamber. Read from the output interface of the probe to be calibrated.

[0024] After data acquisition, the gas replacement process is analyzed first. Since the gas undergoes diffusion, mixing, and spatial homogenization after entering the calibration chamber, the oxygen concentration changes detected by the standard oxygen probe can reflect the formation process of the calibration environment. An atmosphere evolution state quantity is constructed based on the continuously sampled standard oxygen concentration changes, which can be used to describe the actual oxygen concentration state in the current detection area.

[0025] Specifically, the atmospheric evolution state quantity is established by utilizing the proportional relationship between the change in standard oxygen concentration at the current sampling time and the standard oxygen concentration at the previous sampling time: , in, Indicates the first The atmospheric evolution state quantity corresponding to each sampling time, in units of % Indicates the first The standard oxygen concentration at each sampling time, when When the oxygen concentration is below the preset low concentration threshold, the signal-to-noise ratio of the oxygen concentration signal decreases significantly, and the calculation of the normalized migration ratio no longer has physical meaning. Therefore, it is directly taken as... The low concentration threshold is set based on the effective detection limit of the three-electrode oxygen probe and the accuracy of standard gas mixing. As a specific embodiment, it can be set to 0.5% here. This represents the change in standard oxygen concentration between adjacent sampling times. At that time, since there was no data from the previous sampling time, it was directly taken. That is, the atmospheric evolution state quantity at the initial sampling time is equal to the current standard oxygen concentration; To prevent extremely small positive numbers with a denominator of zero, take ; The normalized oxygen concentration migration ratio is the ratio of the change in standard oxygen concentration between adjacent sampling times to the standard oxygen concentration at the previous time. This represents the oxygen concentration migration correction factor.

[0026] After the calculation is completed, the corresponding atmosphere evolution state quantity is obtained for each sampling time. And generate a continuous atmosphere evolution state sequence. As input for subsequent probe response analysis, among which, This indicates the total number of sampling points.

[0027] After obtaining the atmospheric evolution state, the response characteristics of the three-electrode oxygen probe were further analyzed. Because the three-electrode oxygen probe undergoes oxygen molecule diffusion, electrode surface reaction, and electrical signal conversion during detection, its output voltage does not change synchronously with the ambient oxygen concentration, resulting in a certain response time.

[0028] To avoid mixing the effects of gas migration with electrode response hysteresis, an electrode response trajectory quantity is constructed based on the atmosphere evolution state quantity and combined with the change process of the output voltage of the probe to be calibrated. In practice, the actual response time of the probe to be calibrated should be considered. With sampling period Determine the response window length , This is used to ensure that the response window can cover the main transition process of the probe being calibrated from a change in gas state to a basically stable output. This indicates the actual response time, rounded up. This refers to the time required for the output of the probe to be calibrated to reach 90% (or 95%) of its steady-state value. The steady-state value is the reading after the output of the probe to be calibrated has stabilized at a given gas concentration.

[0029] Based on the traditional definition of electrochemical sensor sensitivity, and using the change in state before and after the response window instead of the instantaneous change, the electrode response trajectory of the probe to be calibrated is calculated. , in, Indicates the first The electrode response trajectory of the probe to be calibrated at each sampling time, in units of ; Indicates the first The output voltage of the probe to be calibrated at each sampling time, in units of ; This represents the change in electrode output response, which physically represents the actual voltage change of the probe to be calibrated within the response window due to changes in oxygen concentration, electrode reaction rate, and charge migration. The effective calculation range for this change in electrode output response is... (i.e., at least accumulated) (Calculation can only be performed after sampling points); for In the initial stage, the response window does not yet cover the complete response process, and calculations are not performed. ; Indicates the first The atmospheric evolution state quantity corresponding to each sampling time, in units of ; This represents the effective atmosphere change term, which physically means the change in oxygen concentration state in the oxygen probe detection area within the same response time range; when When the atmospheric change threshold is less than the preset threshold, it indicates that the atmospheric evolution state within the response window has not changed effectively. If the electrode response trajectory is calculated using the original formula, numerical instability, amplification of minor noise, and misjudgment of zero-point drift as a valid response will occur. Therefore, directly taking... The atmosphere change threshold is set based on the measurement accuracy and sampling noise level of the standard oxygen probe, and is used to distinguish between "effective atmosphere change" and "stable atmosphere". As a specific embodiment, the threshold can be set as follows: .

[0030] For each satisfied At each sampling time, the corresponding electrode response trajectory quantity is obtained, and an electrode response trajectory sequence is generated. .

[0031] S2. The atmosphere evolution state quantity and the electrode response trajectory quantity are fused to construct a relative response characteristic quantity. Combined with the nonlinear response and zero-point drift of the three-electrode oxygen probe to be calibrated in different oxygen concentration ranges, a dynamic calibration model is constructed to obtain the calibrated oxygen concentration output result. Based on the calibrated oxygen concentration output result, the parameters in the dynamic calibration model are iteratively updated to obtain the calibration parameters.

[0032] Obtaining the atmospheric evolution state quantity and electrode response trajectory quantity Then, relative response characteristics are further constructed to achieve a unified description of environmental conditions and probe response capabilities.

[0033] Since the oxygen probe's detection results are determined not only by the ambient oxygen concentration but also by the probe's current response capability, a fixed calibration curve cannot be directly established using the oxygen concentration. Therefore, the atmosphere evolution state quantity and the electrode response trajectory quantity are fused together, and a relative response characteristic quantity is constructed based on this. , in, Indicates the first The relative response characteristic at each sampling time point, expressed in % %. This represents the historical average value of the electrode response trajectory of the probe under test, calculated and stored within its rated measurement range during factory acceptance or the most recent successful calibration verification. It is the historical baseline value of the electrode response trajectory of the probe under test, expressed in mV / %. The calibration verification refers to the calibration process in which the probe under test is tested in a standard gas of known concentration, and its calibration output deviation is less than a preset accuracy threshold. This accuracy threshold is preset according to the target accuracy requirements of the probe under test. As a specific embodiment, it can be ±1%FS, i.e., the full scale value. ; This represents the difference between the maximum and minimum standard oxygen concentrations used in this calibration, i.e., the oxygen concentration range throughout the calibration process, expressed as a percentage (%). For example, if the calibration range is from 0% to 21%, then... ; Indicates the first The relative response deviation of the probe to be calibrated at each sampling time; Indicates the first The equivalent oxygen concentration correction amount corresponding to the relative response deviation of the probe to be calibrated at each sampling time.

[0034] Furthermore, since the three-electrode oxygen probe is an electrochemical detection element, its output response exhibits significant non-ideal characteristics. In the low oxygen concentration region, the number of oxygen molecules is small, and the reaction rate on the electrode surface is mainly controlled by the oxygen concentration, resulting in a near-linear response. As the oxygen concentration increases, the oxygen diffusion process on the electrode surface gradually becomes the limiting factor, leading to a decrease in the output increment corresponding to a unit change in oxygen concentration. Simultaneously, during long-term use of the three-electrode oxygen probe, changes in the state of the electrode material and the performance of the electrolyte can cause zero-point drift. Therefore, the relationship between output voltage and oxygen concentration cannot be directly fitted; instead, a dynamic calibration model based on the response state needs to be established using relative response characteristic quantities. The specific process is as follows: First, after completing one full calibration cycle, calculate the global average of the relative response characteristic quantities corresponding to all valid calibration points; the full calibration cycle refers to the complete process of completing the introduction, replacement, stabilization, and data acquisition of a standard gas concentration point; the global average of the relative response characteristic quantities... The calculation formula is: , in, Indicates the number of valid calibration points; Indicates the first The original sampling time sequence number corresponding to each valid calibration point; Indicates the first The relative response characteristic quantity at each sampling moment, expressed as a percentage. The effective calibration point refers to the sampling data point collected after the standard gas in the calibration chamber has been completely replaced and the detection state has reached stability during a single calibration process. A stable state means that within consecutive sampling moments, both the change in standard oxygen concentration and the change in the output voltage of the probe to be calibrated are less than a preset range, indicating that the oxygen concentration in the chamber is essentially uniform and the probe output has reached the corresponding response state. As a specific embodiment, the above range is set for example, if the change in standard oxygen concentration does not exceed ±0.05% within five consecutive sampling cycles, and the change in the output voltage of the probe to be calibrated does not exceed ±0.1% of the full scale, then the oxygen concentration in the calibration chamber and the probe response are considered to have reached a stable state. Each sampling moment that satisfies the stable state is considered a valid calibration point for subsequent calculations. Before calibration begins, pure nitrogen gas is introduced into the calibration chamber to reduce the oxygen concentration to below the preset zero oxygen threshold. After the standard oxygen probe reading stabilizes, the standard oxygen concentration value under these conditions is recorded as the zero-point concentration. Simultaneously, the output voltage of the probe to be calibrated is acquired. Under steady-state conditions, the corresponding relative response characteristic is calculated according to the aforementioned steps, and the obtained relative response characteristic is used as the zero-point response characteristic. The preset zero oxygen threshold is set based on the measurement accuracy of the standard oxygen probe in the low oxygen concentration range. Its value is not higher than ±1% of the full scale of the standard oxygen probe, so as to ensure that the oxygen concentration in the calibration chamber has been replaced to a negligible level. Preferably, it can be set to ±0.2% to ±0.5% of the full scale of the standard oxygen probe.

[0035] Furthermore, based on the deviation of the relative response characteristic quantity from the zero-point state and the average response state, and using the traditional fixed linear mapping relationship as a foundation, the input variable is expanded from the static output voltage to the relative response characteristic quantity that integrates the dynamic response process. A dynamic calibration model is then constructed to achieve systematic compensation for the nonlinear response and zero-point drift of the three-electrode oxygen probe, resulting in the calibrated oxygen concentration output. The specific formula for the dynamic calibration model is as follows: , in, Indicates the first The calibrated oxygen concentration output at each sampling time, in percentage (%) This represents the response scale benchmark quantity, with the unit being %, and its functions include: (1) avoiding when When the denominator is too small when it is close to the global average value of the relative response characteristic, the numerical calculation is unstable; (2) It is used to describe the normal response change scale of the probe; The method of obtaining it is: set the concentration calibration points from low to high according to the standard oxygen concentration. After each concentration calibration point reaches a stable state, take the local average value of the relative response characteristic corresponding to all effective calibration points during the duration of the stable state as the characteristic value of the concentration calibration point; calculate the absolute value of the difference between the characteristic values ​​of two adjacent concentration calibration points in turn, and then take the average of all the absolute values ​​of the differences to obtain the response scale reference quantity. The concentration calibration points refer to the target oxygen concentration values ​​preset before calibration. During the calibration process, if the difference between the characteristic values ​​of adjacent concentration calibration points is zero, it indicates that the probe to be calibrated has no effective response. At this time, the calibration is invalid and the probe should be replaced or repaired. This represents the result after correction for the degree of deviation of the current relative response characteristic from the zero-point response characteristic; Indicates the response scaling correction term; This represents the dynamic proportional correction factor, which is used to make additional adjustments to the change in baseline oxygen concentration after response scale constraint, in order to compensate for the impact of individual probe differences or sensitivity decay on the calibration results. This indicates the proportional change of the current relative response feature relative to the global average. This represents the change in baseline oxygen concentration after being constrained by the response scale.

[0036] Calculate the calibrated oxygen concentration output. Standard oxygen concentration measured by a standard oxygen probe at the same sampling time The difference is used as the detection bias. Multiple sets of data obtained during the calibration process Substituting into the dynamic calibration model, the objective function is to minimize the sum of squared deviations. ,in, For the first The detection bias at each sampling time is optimized using a least squares algorithm, based on the bias determined in step S2. , as well as As initial values, the parameters in the dynamic calibration model are iteratively updated. , as well as until the objective function value is less than the preset convergence threshold. (For example Dimensions are () or the rate of change of the objective function value between two adjacent iterations is less than Stop at the specified time (this convergence criterion is a common criterion for least squares iteration and is common knowledge in this field), and obtain the calibration parameters corresponding to the current three-electrode oxygen probe.

[0037] In summary, an automated calibration method for a three-electrode oxygen probe has been developed.

[0038] The order of the embodiments is for illustrative purposes only and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0039] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0040] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. An automated calibration method for a three-electrode oxygen probe, characterized in that, Specifically, the following steps are included: S1. Construct a sealed calibration chamber and simultaneously collect the standard oxygen concentration and the output voltage of the three-electrode oxygen probe to be calibrated; analyze the gas replacement process and construct the atmosphere evolution state quantity based on the change of standard oxygen concentration. Based on the atmospheric evolution state quantity and combined with the output voltage of the three-electrode oxygen probe to be calibrated, the electrode response trajectory quantity is calculated. S2. The atmosphere evolution state quantity and the electrode response trajectory quantity are fused to construct the relative response characteristic quantity. Combined with the nonlinear response and zero drift of the three-electrode oxygen probe to be calibrated in different oxygen concentration ranges, a dynamic calibration model is constructed to obtain the calibrated oxygen concentration output result. Based on the calibrated oxygen concentration output, the parameters in the dynamic calibration model are iteratively updated to obtain the calibration parameters.

2. The automated calibration method for a three-electrode oxygen probe according to claim 1, characterized in that, S1 specifically includes: Based on the standard oxygen concentration, the change in standard oxygen concentration between the current sampling time and the previous sampling time is calculated. Combined with the standard oxygen concentration at the previous sampling time, the atmosphere evolution state is constructed. The specific formula is as follows: in, Indicates the first Atmosphere evolution state quantity corresponding to each sampling time; Indicates the first The standard oxygen concentration corresponding to each sampling time; Indicates the first Standard oxygen concentration at each sampling time; To prevent extremely small positive numbers with a denominator of zero.

3. The automated calibration method for a three-electrode oxygen probe according to claim 2, characterized in that, S1 specifically includes: A response window is introduced. Based on the atmosphere evolution state variables and the output voltage of the three-electrode oxygen probe to be calibrated, the state changes before and after the response window are calculated. Electrode output response change terms and effective atmosphere change terms are constructed, and the electrode response trajectory is calculated. The specific formula is as follows: in, Indicates the first The electrode response trajectory of the three-electrode oxygen probe to be calibrated at each sampling time; Indicates the first The output voltage of the three-electrode oxygen probe to be calibrated at each sampling time; This represents the change in electrode output response; Indicates the first Atmosphere evolution state quantity corresponding to each sampling time; Indicates the effective atmosphere change term; Indicates the first The output voltage of the three-electrode oxygen probe to be calibrated at each sampling time.

4. The automated calibration method for a three-electrode oxygen probe according to claim 1, characterized in that, S2 specifically includes: Introducing a historical baseline value for the electrode response trajectory, the deviation of the current sampling moment's electrode response trajectory value from its historical baseline value is calculated and converted into an equivalent oxygen concentration correction. This equivalent oxygen concentration correction is then added to the atmosphere evolution state value to obtain the relative response characteristic value, as shown in the following formula: in, Indicates the first The relative response characteristics at each sampling time; Indicates the first Atmosphere evolution state quantity corresponding to each sampling time; Indicates the first The electrode response trajectory of the three-electrode oxygen probe to be calibrated at each sampling time; Historical baseline values ​​representing the electrode response trajectory of the three-electrode oxygen probe to be calibrated; This indicates the difference between the maximum and minimum standard oxygen concentrations used in this calibration. Indicates the first The relative response deviation of the three-electrode oxygen probe to be calibrated at each sampling time; To prevent extremely small positive numbers with a denominator of zero.

5. The automated calibration method for a three-electrode oxygen probe according to claim 4, characterized in that, S2 specifically includes: In the process of constructing the dynamic calibration model, effective calibration points are selected, and the global average value of the relative response characteristics corresponding to all effective calibration points is calculated.

6. The automated calibration method for a three-electrode oxygen probe according to claim 5, characterized in that, S2 specifically includes: The deviations of the relative response characteristic quantity at the current sampling time from the zero-point response characteristic and the global average value of the relative response characteristic quantity are calculated respectively. A response scale benchmark quantity is introduced for correction, resulting in the baseline oxygen concentration change constrained by the response scale. Then, a dynamic proportional correction factor is used to compensate for the nonlinear response and zero-point drift of the three-electrode oxygen probe to be calibrated, constructing a dynamic calibration model to obtain the calibrated oxygen concentration output. The specific formula is as follows: in, Indicates the first The calibrated oxygen concentration output at each sampling time; Indicates the reference quantity of the response scale; This represents the global average value of the relative response characteristic. Indicates zero-point concentration; Indicates the zero-point response characteristics; Indicates the dynamic scaling correction factor; This represents the change in baseline oxygen concentration after being constrained by the response scale.

7. The automated calibration method for a three-electrode oxygen probe according to claim 6, characterized in that, S2 specifically includes: Before calibration begins, pure nitrogen gas is introduced into the calibration chamber. After the oxygen concentration drops below the preset zero oxygen threshold and stabilizes, the standard oxygen concentration value is recorded as the zero-point concentration. At the same time, the output voltage of the three-electrode oxygen probe to be calibrated is acquired, and the relative response characteristic of the three-electrode oxygen probe to be calibrated under this state is calculated as the zero-point response characteristic according to the aforementioned steps.

8. The automated calibration method for a three-electrode oxygen probe according to claim 6, characterized in that, S2 specifically includes: The difference between the calibrated oxygen concentration output and the standard oxygen concentration measured by the standard oxygen probe in the calibration chamber at the same sampling time is calculated to obtain the detection deviation. Based on the detection deviation, the dynamic calibration model is iteratively updated to obtain the calibration parameters corresponding to the three-electrode oxygen probe to be calibrated.

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