阅读说明：本技术 一种参考气室气体吸收峰轮廓中心检索方法 (Reference gas chamber gas absorption peak profile center retrieval method ) 是由 郭清华 张书林 于庆 孙世岭 樊荣 槐利 饶兴鑫 梁光清 张远征 王尧 王博文 于 2021-08-24 设计创作，主要内容包括：本发明涉及一种参考气室气体吸收峰轮廓中心检索方法,属于气体检测领域。该方法包括以下步骤：激光器注入波长扫描调制电流；采集参考气室吸收波形数组；计算出抽样波形数据的斜率数据组；计算平均斜率值,检索出斜率最小值、斜率最大值及其对应的序号；激光器吸收峰中心轮廓快速判定规则：设定偏移量绝对值判定阀值,对应的大小关系,实现吸收峰轮廓中心位置判定和计算；发送结果给激光器中心回归调节模块。本发明通过快速识别激光器吸收峰轮廓中心是否还在有效扫描波形内及对应位置,输出给中心自动回归调节模块实现正确快速粗调将中心调节回来,以保证后续谐波解调算法的有效性。(The invention relates to a method for searching the profile center of a gas absorption peak of a reference gas chamber, belonging to the field of gas detection. The method comprises the following steps: injecting wavelength scanning modulation current into the laser; collecting an absorption waveform array of a reference air chamber; calculating a slope data group of the sampled waveform data; calculating an average slope value, and searching a slope minimum value, a slope maximum value and a corresponding serial number thereof; the laser absorption peak center profile rapid determination rule is as follows: setting an absolute value judgment threshold value of the offset, and realizing judgment and calculation of the central position of the profile of the absorption peak according to the corresponding magnitude relation; and sending the result to a laser center regression adjusting module. According to the invention, whether the center of the profile of the absorption peak of the laser is still in the effective scanning waveform and the corresponding position is rapidly identified, and the result is output to the center automatic regression adjusting module to realize accurate and rapid coarse adjustment and adjust the center back, so that the effectiveness of a subsequent harmonic demodulation algorithm is ensured.)

1. A method for searching the profile center of a gas absorption peak of a reference gas chamber is characterized by comprising the following steps: the method comprises the following steps:

s1: injecting wavelength scanning modulation current F (t) into the laser;

F(t)＝ks×t+A×Tune(t)+D (1)

wherein: t is 0 to Q.T; ks is current scanning slope, A is current modulation amplitude, Q is modulation period accumulation, tune (T) is a modulation function of period T, and D is direct current component;

s2: acquisition reference air chamber absorption waveform array S_ADC_REF[Q.M]；

Reference gas chamber waveform sampling function: s_ADC_REF(i)＝Ψ(i)×[ks×i+A×Tune(i)] (2)

Wherein: i is 0,1,2 … N, N is Q.T/Ts; the sampling time interval Ts is equal to T/M, and M is more than or equal to 3; psi (i) is the attenuation coefficient of the optical wave;

s3: s at n.M_ADC_REF[Q.M]The array samples at equal intervals, and calculates the slope data group RAW _ REF [ Q/n ] of the sampled waveform data](ii) a n is positive integer;

RAW_REF[i]＝[SADC_REF[(i+1)×n.M]-SADC_REF[i×n.M]]/n.M×10 (3)

the slope value is amplified by 10 times, and one more bit is reserved; wherein: i is 0,1,2 … N, N is Q.T/Ts;

s4: calculating an average slope value KAVR, and searching a slope minimum value Kmin, a slope maximum value Kmax and corresponding serial numbers thereof;

Kmin＝Min{RAW_REF[i]-KAVR} (5)

Kmax＝Max{RAW_REF[i]-KAVR} (6)

wherein: i, min, max belongs to 0 to (Q/n-1);

s5: calculating absolute offset values beta _ Kmin and beta _ Kmax corresponding to the minimum value and the maximum value of the slope;

β_Kmax＝|(Kmax-KAVR)|/KAVR×10 (7)

β_Kmin＝|(Kmin-KAVR)|/KAVR×10 (8)

note that the absolute value of the offset is amplified by 10 times, and one more significant bit is retained;

s6: carrying out a rapid determination rule on the central profile of the laser absorption peak;

setting an absolute value judgment threshold delta H of the offset, and taking the value of 3-8 to ensure that the algorithm can identify effective absorption offset when the concentration of the reference gas chamber is low; judging the corresponding magnitude relation of beta _ Kmax, beta _ Kmin and delta H, and realizing the central position C of the profile of the absorption peak according to the relative position relation of the position numbers min and max of Kmin and Kmax_θJudging and calculating;

s7: output C_θThe values are sent to a laser center regression adjustment module.

2. The method according to claim 1, wherein the center of the profile of the gas absorption peak of the reference gas chamber is searched for: the center position C of the profile of the absorption peak is realized_θThe judgment and the counting are specifically as follows:

(1) when the offset amount satisfies β _ Kmax < Δ H & & β _ Kmin > Δ H:

when min is greater than max, the central profile of the absorption peak is shifted to the lower half position of the extreme of the waveform, and then:

C_θ＝min×n.M (9)

② otherwise, C_θ0; represents a profile without absorption peaks;

(2) if β _ Kmax > Δ H & & β _ Kmin < Δ H is satisfied:

when max < min indicates that the central profile of the absorption peak is shifted to the upper half position of the extreme end of the waveform, then:

C_θ＝max×n.M (10)

② otherwise, C_θ0; represents a profile without absorption peaks;

(3) if β _ Kmax > - [ Δ H & & β _ Kmin > - [ Δ H ] is satisfied:

when max > min & & min > 10& & min < (Q/n) × 0.9), it indicates that the absorption peak center profile is within the normal search range, then:

C_θ＝(max+min)/2×n.M (11)

subsequently, a reference waveform harmonic wave absorption retrieval algorithm is directly introduced to correct the center of the profile of the absorption peak;

(Q/n) × 0.9) when max > min & & min > ((Q/n) × indicates that the absorption peak center profile is shifted to the uppermost position of the waveform, then:

C_θ＝(max+min)/2×n.M (12)

and when min > ((Q/n) multiplied by 0.9), the central profile of the absorption peak is shifted to the upper end position of the waveform, and if the positive shift is too large:

C_θ＝min×n.M (13)

when max > min & & min <10, the central profile of the absorption peak is shifted to the lower half position of the waveform;

C_θ＝(max+min)/2×n.M (14)

when max is less than min, the central outline of the absorption peak is shifted to the lowest position of the waveform;

C_θ＝max×n.M (15)

sixthly, otherwise, C_θ0; represents a profile without absorption peaks;

(4) when the beta _ Kmax and the beta _ Kmin do not satisfy the conditions (1), (2) and (3), C_θ0; indicating no absorption peak profile.

3. The method according to claim 2, wherein the center of the profile of the gas absorption peak of the reference gas chamber is searched for: and the collection of the absorption waveform of the reference gas chamber is completed by gas absorption of the reference gas chamber.

4. The method according to claim 3, wherein the center of the profile of the gas absorption peak of the reference gas chamber is searched for: the S5 specifically includes: calculating the absolute values beta _ Kmin and beta _ Kmax of the offset corresponding to the minimum value and the maximum value of the slope, setting an absolute value determination threshold value delta H of the offset, taking a value of 3-8 for judgment, and calculating the center position of the profile of the absorption peak by combining the relative position relationship of the minimum value, the maximum value and the position number min of the slope and the max.

5. The method according to claim 4, wherein the center of the profile of the gas absorption peak of the reference gas chamber is searched for: said output C_θ，C_θWhen the value is not 0, transmitting the value to a laser center regression adjusting module; c_θWhen 0, no absorption peak profile is indicated and the device fails.

Technical Field

The invention belongs to the field of gas detection, and relates to a method for searching the profile center of a gas absorption peak of a reference gas chamber.

Background

The laser gas detection method and the laser gas detection device which are adopted at present are mainly installed in an environment with severe working conditions for long-term work, and the detection device is easily influenced by factors such as abnormal high temperature, low temperature and high humidity of the environment, so that the phenomena of overlarge measurement deviation or measurement failure and the like caused by aging of a laser and a temperature control module and attenuation of coupling efficiency of a heat dissipation structure are caused. By adopting a light splitting technology and combining a detection device of a reference air chamber, after the detection device runs for a long time in a severe working environment, the profile of a central absorption peak of a laser deviates from an effective wavelength scanning range and is overlarge occasionally, so that equipment can report errors directly; or the position of the central absorption peak is not effectively identified, so that the adjustment direction of the central adjustment module is wrong, and the error report of the equipment is caused.

In order to solve the above phenomena and ensure the reliability of the detection device under the severe industrial and mining conditions, a detection algorithm capable of quickly and reliably determining the center of the profile of the gas absorption peak of the reference gas chamber is urgently needed at present, so as to accurately determine the position deviation direction of the center profile of the absorption peak in the scanning waveform to realize the accurate and quick rough adjustment of the absorption peak of the laser and keep the measurement precision of the detection device; if the scanning range is completely deviated, the failure of the detection device is directly prompted, so that maintenance personnel can replace and maintain the detection device in time, and the long-term safety production of industrial and mining enterprises is ensured

Disclosure of Invention

In view of the above, the present invention provides a method for searching the center of a profile of a gas absorption peak in a reference gas chamber. The method can rapidly and accurately judge the deviation position of the absorption peak of the laser for various laser gas concentration devices with reference gas chambers in the industrial and mining industries, and output the deviation position to the central automatic correction module to realize correct central regression adjustment, thereby ensuring the measurement precision and reliability of the detection device.

In order to achieve the purpose, the invention provides the following technical scheme:

a method for searching the profile center of a gas absorption peak of a reference gas chamber comprises the following steps:

s1: injecting wavelength scanning modulation current F (t) into the laser;

F(t)＝ks×t+A×Tune(t)+D (1)

wherein: t is 0 to Q.T; ks is current scanning slope, A is current modulation amplitude, Q is modulation period accumulation, tune (T) is a modulation function of period T, and D is direct current component;

s2: acquisition reference air chamber absorption waveform array S_ADC_REF[Q.M]；

Reference gas chamber waveform sampling function: s_ADC_REF(i)＝Ψ(i)×[ks×i+A×Tune(i)] (2)

Wherein: i is 0,1,2 … N, N is Q.T/Ts; the sampling time interval Ts is equal to T/M, and M is more than or equal to 3; psi (i) is the attenuation coefficient of the optical wave;

s3: s at n.M_ADC_REF[Q.M]The arrays are sampled at equal intervals, and a slope data group RAW _ REF [ Q-n](ii) a n is positive integer;

RAW_REF[i]＝[SADC_REF[(i+1)×n.M]-SADC_REF[i×n.M]]/n.M×10 (3)

the slope value is amplified by 10 times, and one more bit is reserved; wherein: i is 0,1,2 … N, N is Q.T/Ts;

s4: calculating an average slope value KAVR, and searching a slope minimum value Kmin, a slope maximum value Kmax and corresponding serial numbers thereof;

Kmin＝Min{RAW_REF[i]-KAVR} (5)

Kmax＝Max{RAW_REF[i]-KAVR} (6)

wherein: i, min, max belongs to 0 to (Q/n-1);

s5: calculating absolute offset values beta _ Kmin and beta _ Kmax corresponding to the minimum value and the maximum value of the slope;

β_Kmax＝|(Kmax-KAVR)|/KAVR×10 (7)

β_Kmin＝|(Kmin-KAVR)|/KAVR×10 (8)

note that the absolute value of the offset is amplified by 10 times, and one more significant bit is retained;

s6: carrying out a rapid determination rule on the central profile of the laser absorption peak;

setting an absolute value judgment threshold delta H of the offset, and taking the value of 3-8 to ensure that the algorithm can identify effective absorption offset when the concentration of the reference gas chamber is low; judging the corresponding magnitude relation of beta _ Kmax, beta _ Kmin and delta H, and realizing the central position C of the profile of the absorption peak according to the relative position relation of the position numbers min and max of Kmin and Kmax_θJudging and calculating;

s7: output C_θThe values are sent to a laser center regression adjustment module.

Optionally, the center position C of the profile of the absorption peak is realized_θThe judgment and the counting are specifically as follows:

(1) when the offset amount satisfies β _ Kmax < Δ H & & β _ Kmin > Δ H:

when min is greater than max, the central profile of the absorption peak is shifted to the lower half position of the extreme of the waveform, and then:

C_θ＝min×n.M (9)

② otherwise, C_θ0; represents a profile without absorption peaks;

(2) if β _ Kmax > Δ H & & β _ Kmin < Δ H is satisfied:

when max < min indicates that the central profile of the absorption peak is shifted to the upper half position of the extreme end of the waveform, then:

C_θ＝max×n.M (10)

② otherwise, C_θ0; represents a profile without absorption peaks;

(3) if β _ Kmax > - [ Δ H & & β _ Kmin > - [ Δ H ] is satisfied:

when max > min & & min > 10& & min < (Q/n) × 0.9), it indicates that the absorption peak center profile is within the normal search range, then:

C_θ＝(max+min)/2×n.M (11)

subsequently, a reference waveform harmonic wave absorption retrieval algorithm is directly introduced to correct the center of the profile of the absorption peak;

(Q/n) × 0.9) when max > min & & min > ((Q/n) × indicates that the absorption peak center profile is shifted to the uppermost position of the waveform, then:

C_θ＝(max+min)/2×n.M (12)

and when min > ((Q/n) multiplied by 0.9), the central profile of the absorption peak is shifted to the upper end position of the waveform, and if the positive shift is too large:

C_θ＝min×n.M (13)

when max > min & & min <10, the central profile of the absorption peak is shifted to the lower half position of the waveform;

C_θ＝(max+min)/2×n.M (14)

when max is less than min, the central outline of the absorption peak is shifted to the lowest position of the waveform;

C_θ＝max×n.M (15)

sixthly, otherwise, C_θ0; represents a profile without absorption peaks;

(4) when the beta _ Kmax and the beta _ Kmin do not satisfy the conditions (1), (2) and (3), C_θ0; indicating no absorption peak profile.

Optionally, the acquiring of the absorption waveform of the reference gas chamber is performed by gas absorption of the reference gas chamber.

Optionally, the S5 specifically includes: calculating the absolute values beta _ Kmin and beta _ Kmax of the offset corresponding to the minimum value and the maximum value of the slope, setting an absolute value determination threshold value delta H of the offset, taking a value of 3-8 for judgment, and calculating the center position of the profile of the absorption peak by combining the relative position relationship of the minimum value, the maximum value and the position number min of the slope and the max.

Optionally, the output C_θ，C_θWhen the value is not 0, transmitting the value to a laser center regression adjusting module; c_θWhen 0, no absorption peak profile is indicated and the device fails.

The invention has the beneficial effects that: the invention can accurately judge the position deviation direction of the central profile of the absorption peak in the scanning waveform, realize the accurate and quick rough adjustment of the absorption peak of the laser and keep the measurement precision of the detection device; and the complete deviation of the central profile of the absorption peak from the scanning range can be quickly and accurately judged, the failure of the detection device is directly prompted, so that maintenance personnel can replace and maintain the detection device in time, and the long-term safety production of industrial and mining enterprises is ensured.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a flow chart of the present invention;

FIG. 2 shows the sample data S_ADC_REF[2000]And (4) waveform diagrams.

FIG. 3 is a normal absorption peak curve;

FIG. 4 is a graph of the extreme downward shift absorption peak

FIG. 5 is a graph of an extreme upward shift absorption peak;

FIG. 6 is a graph of complete deviation from no absorption peak;

fig. 7 is a hardware schematic of the present invention.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.

FIG. 1 is a flow chart of the detection method, the method comprises the following steps:

the method comprises the following steps: injecting wavelength scanning modulation current F (t) into the laser;

F(t)＝11.7×t+100×sine(2π/2×t/0.2)+1520 (1)

wherein Q is 200, T is 2ms, and Ts is 0.2 ms.

Step two: acquisition reference air chamber absorption waveform array S_ADC_REF[2000]As shown in fig. 2.

Reference gas chamber waveform sampling function: s_ADC_REF(i)＝0.5×[ks×i+10×Tune(i)] (2)

Wherein: i is 0,1,2 … 2000; the sampling time interval Ts is 0.2ms, and M is 10.

Step three: s is carried out with M10_ADC_REF[2000]The array samples at equal intervals, and calculates the slope data group RAW _ REF [200 ] of the sampled waveform data]A step (2);

RAW_REF[i]＝SADC_REF[(i+1)×10]-SADC_REF[i×10] (3)

wherein: the slope value is magnified by a factor of 10, i being 0,1,2 … 2000.

Step four: calculating an average slope value KAVR, and searching a slope minimum value Kmin, a slope maximum value Kmax and corresponding serial numbers thereof;

Kmin＝Min{RAW_REF[i]-KAVR} (5)

Kmax＝Max{RAW_REF[i]-KAVR} (6)

wherein: i, min, max is belonged to (0-199).

Step five: calculating absolute offset values beta _ Kmin and beta _ Kmax corresponding to the minimum value and the maximum value of the slope;

β_Kmax＝|(Kmax-KAVR)|/KAVR×10 (7)

β_Kmin＝|(Kmin-KAVR)|/KAVR×10 (8)

step six: carrying out a laser absorption peak center profile rapid judgment rule:

setting an offset absolute value judgment threshold value delta H to be 5;

the specific judgment algorithm is as follows:

(1) as shown in fig. 3, the normal waveform is calculated to obtain KAVR 102, β _ Kmax 56, β _ Kmin 45, max 110, min 86; satisfies the decision rule (max)>＝min&&min>＝10&&min<180) indicating that the absorption peak center profile is within the normal search range, C)_θ＝980。

(2) As shown in fig. 4, the normal waveform is calculated to obtain KAVR 98, β _ Kmax 3, β _ Kmin 8, max 4, and min 20; satisfies the determination rule (β _ Kmax)<5&&β_Kmin>5) Condition (min) of>max)，C_θ200 parts of a total weight; indicating that the absorption peak center profile is shifted to the lower half of the waveform extremity.

(3) As shown in fig. 5, the normal waveform is calculated to obtain KAVR 94, β _ Kmax 10, β _ Kmin 3, max 176, and min 190; satisfies the determination rule (β _ Kmax)>5&&β_Kmin<5) Condition (2) of (2) and (max)<min)，C_θ1760; indicating that the absorption peak center profile is shifted to the upper half of the waveform extremes.

(4) As shown in fig. 6, the normal waveform is calculated to obtain KAVR 100, β _ Kmax 3, β _ Kmin 2, max 156, and min 56; beta _ Kmax, beta _ Kmin do not satisfy the above-mentioned [6- (1), (2), (3)]Under the condition of (1), then C_θ0; indicating no absorption peak profile.

Step seven: output C_θThe values are sent to a laser center regression adjustment module.

Fig. 7 is a hardware schematic of the present invention. For the gas absorption waveform signal generated by the light beam transmitted through the reference gas chamber, the core processor judges the deviation direction of the center position of the absorption peak profile according to the detection algorithm, and calls a laser center regression adjusting module to realize quick coarse adjustment or output prompt information of the profile without the absorption peak. In the present embodiment, a DFB laser is used as the laser.

Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.