Digital display system and method for measured value of light interference type methane measuring device

Abstract

The invention relates to the technical field of methane detection, in particular to a digital display system and method for a measured value of a light interference type methane measurer. The server comprises an image acquisition module which is used for performing image acquisition on interference fringes which are formed based on a preset light interference strategy and contain methane information to form corresponding image data; the preprocessing module is used for preprocessing the formed image data; the feature extraction module is used for extracting key features of interference fringes from the image data based on a preset feature extraction strategy according to the preprocessed image data; the key features comprise stripe spacing, stripe brightness change and phase information; and the calculation module is used for calculating the corresponding methane concentration based on a preset methane calculation model according to the extracted key features of the interference fringes, and sending the calculated methane concentration to a user side for visual display.

Description

Technical Field

[0001] The present invention relates to the technical field of methane detection, and in particular to a measurement value digital display system and method of an optical interference type methane detector. Background Art

[0002] In the underground working environment of coal mines, the accumulation of methane gas not only threatens the lives of miners, but may also lead to serious safety accidents, such as explosions. Therefore, accurate and timely monitoring of methane concentration in mines is a key link in ensuring safe production in mines.

[0003] At present, the most widely used optical interference methane detectors on the market (such as methane detectors) mainly work on the principle of Michelson interferometer. This type of instrument detects the presence and concentration of methane through the interference effect of light waves at different path lengths. Specifically, when an air sample containing methane passes through the optical path, the methane molecules absorb light of specific wavelengths, which will cause changes in the interference fringes. The operator needs to observe the interference fringe image presented by the light passing through the optical path with the naked eye to read the methane concentration value. However, this method has many limitations and shortcomings:

[0004] Traditional optical interferometry methane detectors require manual reading and recording, and have a low degree of automation. In frequent monitoring tasks, this manual operation is not only time-consuming and labor-intensive, but also increases the risk of human error.

[0005] There are differences in experience and skills between different operators, which will lead to more subjective readings and it is difficult to ensure the consistency and accuracy of each reading.

[0006] Therefore, there is an urgent need for a digital display system and method for the measured value of an optical interference methane detector, which can realize the automation of methane concentration measurement, improve the accuracy of methane concentration measurement, and reduce the influence of human factors. Summary of the invention

[0007] One of the purposes of the present invention is to provide a light interference type methane measuring instrument measurement value digital display system and method, which can realize the automation of methane concentration measurement, improve the accuracy of methane concentration measurement, and reduce the influence of human factors.

[0008] In order to achieve the above-mentioned purpose, a light interference type methane detector measurement value digital display system is provided, including a service end and a user end;

[0009] The server includes:

[0010] An image acquisition module, used to acquire images of interference fringes containing methane information formed based on a preset light interference strategy to form corresponding image data;

[0011] A preprocessing module, used for performing preprocessing operations on the formed image data;

[0012] A feature extraction module is used to extract key features of interference fringes from image data based on the image data after preprocessing operations and based on a preset feature extraction strategy; the key features include fringe spacing, fringe brightness change, and phase information;

[0013] The calculation module is used to calculate the corresponding methane concentration according to the key features of the extracted interference fringes based on a pre-set methane calculation model, and send the calculated methane concentration to the user end for visual display.

[0014] Technical principles and effects of this solution: In this solution, first, according to the preset light interference strategy, the interference fringes containing methane information are imaged to form corresponding image data. In order to ensure the clarity of the image data and the reliability of subsequent feature extraction of the image data, the formed image data is preprocessed.

[0015] Then, according to the image data after the preprocessing operation, based on the preset feature extraction strategy, the key features of the interference fringes of the image data are extracted; the key features include fringe spacing, fringe brightness change, and phase information;

[0016] According to the key features of the extracted interference fringes, based on the pre-set methane calculation model, the corresponding methane concentration is calculated, and the calculated methane concentration is sent to the user end for visual display.

[0017] 1. Through the combination of optical interference technology and image recognition technology, the automatic extraction of image features and the subsequent accurate measurement of methane concentration are realized. The entire process from image acquisition to feature extraction to concentration calculation is automated, without the need for human intervention, thus reducing the impact of human factors.

[0018] 2. It realizes the actual monitoring of methane concentration and quickly feeds back to the user end for display, which greatly improves the user experience.

[0019] Furthermore, the preset light interference strategy is:

[0020] Using a stable light source to emit monochromatic light of a specific wavelength; the specific wavelength is selected to be a wavelength at which methane has a strong absorption characteristic;

[0021] Based on the monochromatic light of a specific wavelength emitted by a light source, the light beam corresponding to the monochromatic light is divided into two paths by a beam splitter, one of which is used as a reference path, which passes through air gas without methane, and the other is used as a measurement path, which passes through a sample gas containing methane; the light beams on the two paths are re-merged at the merging point after passing through their respective paths, at which time the light waves interfere with each other to form interference fringes.

[0022] Beneficial effects: In this scheme, a stable light source is used, such as a laser or LED light source, which can emit monochromatic light of a specific wavelength. The selection of the specific wavelength is based on the absorption characteristics of methane. Methane has a strong absorption capacity in certain bands (such as the near-infrared region), and the light in these bands will be strongly absorbed by methane molecules.

[0023] Since methane has strong absorption characteristics at specific wavelengths, this method can detect the presence of methane very sensitively. Even trace amounts of methane can cause significant absorption effects, making this method very suitable for detecting low-concentration methane. It can reduce the impact of other gases on the measurement results. This method can effectively avoid errors caused by interfering gases and improve measurement accuracy.

[0024] The formation of interference fringes depends on the phase difference between the two beams at the merging point. When the phase difference between the reference light and the measurement light changes, the interference fringes will also change. By analyzing the changes in the interference fringes, the methane concentration can be quantitatively measured. Optical interferometry is a non-contact measurement method that does not require direct contact with the gas being measured. This means that safe measurements can be made in harsh environments such as high temperature and high pressure.

[0025] Further, the preprocessing module includes:

[0026] A conversion and recognition module, used to convert the formed image data into a corresponding grayscale image, and identify the black stripe line spectrum to be identified in the grayscale image based on a preset segmentation pixel threshold;

[0027] The morphological processing module is used to connect the scale areas divided by the scale lines and the spectrum lines in the black stripe line spectrum to be identified through the expansion strategy preset in the morphology according to the identified black stripe line spectrum to be identified, so as to form a coherent scale area;

[0028] The contour detection module is used to perform Hough transformation on the four sides of the rectangular outer contour of the ruler area according to the formed coherent ruler area, and fit the corresponding outer contour of the ruler area;

[0029] The rotation module is used to determine the direction of the ruler area after fitting the outer contour, and rotate the corresponding ruler area to a horizontal position to form image data after preprocessing operation.

[0030] Beneficial effects: In this solution, the color dimension is reduced by converting the formed image data into the corresponding grayscale image, which reduces the computational complexity. By setting the threshold segmentation method, the stripe features can be effectively highlighted and the background interference can be reduced. Morphological processing ensures the coherence of the stripe line spectrum. Hough transform provides accurate contour detection. Improve consistency: Rotation correction eliminates angle deviation and improves the consistency of the image.

[0031] Further, the feature extraction strategy includes a first extraction strategy; the first extraction strategy includes the following steps:

[0032] According to the image data after the preprocessing operation, the image data is converted from the spatial domain to the frequency domain through Fourier transform, and the corresponding frequency spectrum is obtained;

[0033] Normalize and smooth the acquired spectrum;

[0034] Perform peak recognition on the processed spectrum to identify the positions corresponding to each peak in the frequency domain;

[0035] According to the positions of the identified peaks in the frequency domain, the fringe spacing between the peaks is calculated based on a preset fringe spacing calculation formula;

[0036] The preset stripe spacing calculation formula is:

[0037]

[0038] Where d is the fringe spacing between corresponding peaks, (u2, v2) is the position of one of the peaks in the frequency domain, and (u1, v1) is the position of the other peak in the frequency domain.

[0039] Beneficial effects: In this scheme, the conversion of image data from the spatial domain to the frequency domain is realized through Fourier transform, which can highlight the periodic features in the image and facilitate subsequent analysis. At the same time, normalization and smoothing processing improve the stability of the numerical values ​​and the visibility of the main features. The fringe spacing is calculated by the peak position in the frequency domain, and high-precision results can be obtained.

[0040] Furthermore, the server also includes:

[0041] A historical data acquisition module is used to obtain historical fringe spacing, historical fringe brightness changes, historical phase information and corresponding historical methane concentrations corresponding to historical image data from a historical database, and divide the corresponding data into a training set and a validation set;

[0042] Model building module, used to build the corresponding methane calculation model;

[0043] A training module is used to input the historical fringe spacing, historical fringe brightness changes, and historical phase information in the training set as input data into the methane calculation model, and use the historical methane concentration as output data to train the methane calculation model;

[0044] A verification module is used to input the historical fringe spacing, historical fringe brightness change, and historical phase information in the verification set as input data into the trained methane calculation model after each training of the methane calculation model is completed, output the corresponding predicted methane concentration, and calculate the corresponding prediction error value based on the predicted methane concentration and the historical methane concentration corresponding to the verification set based on a preset prediction error value calculation formula, and judge whether the prediction error value is less than a preset error threshold. If so, the trained methane calculation model is judged to be a valid model, otherwise the trained methane calculation model is judged to be an invalid model, and the training module is continued to be executed to retrain the methane calculation model;

[0045] The prediction error value calculation formula is:

[0046]

[0047] Where W is the prediction error value, y i is the predicted methane concentration corresponding to image data i, is the historical methane concentration corresponding to the validation set image data i, ∝ is the preset weight value, ∝ i is the weight value corresponding to the image data i.

[0048] Beneficial effects: In this scheme, a large amount of historical data is obtained from the historical database to ensure the adequacy of model training and verification. Through multiple iterations of training and verification, the model parameters are continuously adjusted to make the model perform better in predicting methane concentration. Through the preset error threshold, the prediction error of the model is ensured to be within a reasonable range, which enhances the reliability and practicality of the model.

[0049] At the same time, the model can be adjusted according to actual needs, for example, by changing the weight value ∝ i To optimize the error calculation formula to adapt to different application scenarios, the calculation of the prediction error value is more real and accurate, which greatly improves the reliability and scientificity of the model verification.

[0050] The present invention also provides a method for digitally displaying the measured value of an optical interference type methane detector, using the above-mentioned digital display system for the measured value of an optical interference type methane detector, comprising the following steps:

[0051] S1. Capturing images of interference fringes containing methane information formed based on a preset light interference strategy to form corresponding image data;

[0052] S2, performing preprocessing operation on the formed image data;

[0053] S3, extracting key features of interference fringes from the image data based on the image data after the preprocessing operation and based on a preset feature extraction strategy; the key features include fringe spacing, fringe brightness change, and phase information;

[0054] S4. According to the key features of the extracted interference fringes and based on a pre-set methane calculation model, the corresponding methane concentration is calculated, and the calculated methane concentration is sent to the user end for visual display. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a logic block diagram of the digital display system of the optical interference methane detector in the first embodiment of the present invention;

[0056] Figure 2 This is a flow chart of the method for digitally displaying the measured values ​​of the optical interference methane detector in the first embodiment of the present invention. DETAILED DESCRIPTION

[0057] The following is further described in detail through specific implementation methods:

[0058] Embodiment 1

[0059] A digital display system for measuring the value of a light interference methane detector, basically as follows Figure 1 As shown, it is installed in the corresponding mobile phone, tablet, host or embedded module, and its corresponding functions include server and user;

[0060] The server includes:

[0061] The image acquisition module is used to acquire images of interference fringes containing methane information formed based on a preset light interference strategy to form corresponding image data; in this embodiment, the preset light interference strategy is:

[0062] Using a stable light source to emit monochromatic light of a specific wavelength; the specific wavelength is selected to be a wavelength at which methane has a strong absorption characteristic;

[0063] Based on the monochromatic light of a specific wavelength emitted by a light source, the light beam corresponding to the monochromatic light is divided into two paths by a beam splitter, one of which is used as a reference path, which passes through air gas without methane, and the other is used as a measurement path, which passes through a sample gas containing methane; the light beams on the two paths are re-merged at the merging point after passing through their respective paths, at which time the light waves interfere with each other to form interference fringes.

[0064] In order to better capture the image of the interference fringes, a 2-megapixel wide dynamic anti-backlight camera module is used with a telephoto M12 lens with a focal length of 25 mm to shoot the interference pattern and obtain image data.

[0065] A preprocessing module, used for performing preprocessing operations on the formed image data;

[0066] In this embodiment, the preprocessing module includes:

[0067] A conversion and recognition module, used to convert the formed image data into a corresponding grayscale image, and identify the black stripe line spectrum to be identified in the grayscale image based on a preset segmentation pixel threshold;

[0068] The morphological processing module is used to connect the scale areas divided by the scale lines and the spectrum lines in the black stripe line spectrum to be identified through the expansion strategy preset in the morphology according to the identified black stripe line spectrum to be identified, so as to form a coherent scale area;

[0069] The contour detection module is used to perform Hough transformation on the four sides of the rectangular outer contour of the ruler area according to the formed coherent ruler area, and fit the corresponding outer contour of the ruler area;

[0070] The rotation module is used to determine the direction of the ruler area after fitting the outer contour, and rotate the corresponding ruler area to a horizontal position to form the image data after the preprocessing operation. Specifically, the characteristics of the spectrum are analyzed, and the spectral lines to be identified are in the form of thick black stripes, which are different from the sub-spectral lines that do not need to be paid attention to. In the color image, the three RGB channels of the black stripe spectrum are close to 0. Using this feature, the spectral lines to be identified can be quickly extracted. Then, using the expansion method in morphology, the ruler area divided by the scale lines and spectral lines is connected into a coherent area, and then the Hough transform is used to fit the four sides of the rectangular outer contour of the ruler area to obtain the outer contour of the ruler area. Since it is impossible to ensure that the ruler area is strictly horizontal, it is also necessary to rotate the ruler area to a horizontal position.

[0071] The feature extraction module is used to extract the key features of the interference fringes from the image data based on the preset feature extraction strategy according to the image data after the preprocessing operation; the key features include fringe spacing, fringe brightness change, and phase information; in this embodiment, under the condition of fixed lens parameters and object distance, the size of the scale area in the image after imaging is the same, so the scale area rotated to the horizontal can be cropped according to the preset parameters to obtain the focus area from the start point (0%) to the end point (10%) of the scale line, and the numbers that affect the recognition are cut off at the same time. The spectrum lines are extracted by the preprocessing method, and the constraints are imposed to finally obtain two relatively thick and black spectrum lines. The spectrum lines are refined into straight lines, and the indication is determined according to the relative position of the straight lines in the focus area.

[0072] The feature extraction strategy includes a first extraction strategy; the first extraction strategy includes the following steps:

[0073] According to the image data after the preprocessing operation, the image data is converted from the spatial domain to the frequency domain through Fourier transform, and the corresponding frequency spectrum is obtained;

[0074] Normalize and smooth the acquired spectrum;

[0075] Perform peak recognition on the processed spectrum to identify the positions corresponding to each peak in the frequency domain;

[0076] According to the positions of the identified peaks in the frequency domain, the fringe spacing between the peaks is calculated based on a preset fringe spacing calculation formula;

[0077] The preset stripe spacing calculation formula is:

[0078]

[0079] Where d is the fringe spacing between corresponding peaks, (u2, v2) is the position of one of the peaks in the frequency domain, and (u1, v1) is the position of the other peak in the frequency domain.

[0080] In this embodiment, when extracting key features of stripe brightness changes and phase information, the specific extraction strategy is: analyzing the brightness change pattern of the stripe area through grayscale histogram or local brightness statistics.

[0081] The phase unwrapping algorithm is used to extract phase information from the frequency domain of the interference fringes and calculate the cross-power spectrum. This information can reflect the displacement of the light interference fringes and is indirectly related to the methane concentration.

[0082] The calculation module is used to calculate the corresponding methane concentration according to the key features of the extracted interference fringes based on a pre-set methane calculation model, and send the calculated methane concentration to the user end for visual display.

[0083] The server also includes:

[0084] A historical data acquisition module is used to obtain historical fringe spacing, historical fringe brightness changes, historical phase information and corresponding historical methane concentrations corresponding to historical image data from a historical database, and divide the corresponding data into a training set and a validation set;

[0085] Model building module, used to build the corresponding methane calculation model;

[0086] A training module is used to input the historical fringe spacing, historical fringe brightness changes, and historical phase information in the training set as input data into the methane calculation model, and use the historical methane concentration as output data to train the methane calculation model;

[0087] A verification module is used to input the historical fringe spacing, historical fringe brightness change, and historical phase information in the verification set as input data into the trained methane calculation model after each training of the methane calculation model is completed, output the corresponding predicted methane concentration, and calculate the corresponding prediction error value based on the predicted methane concentration and the historical methane concentration corresponding to the verification set based on a preset prediction error value calculation formula, and judge whether the prediction error value is less than a preset error threshold. If so, the trained methane calculation model is judged to be a valid model, otherwise the trained methane calculation model is judged to be an invalid model, and the training module is continued to be executed to retrain the methane calculation model;

[0088] The prediction error value calculation formula is:

[0089]

[0090] Where W is the prediction error value, y i is the predicted methane concentration corresponding to image data i, is the historical methane concentration corresponding to the validation set image data i, ∝ is the preset weight value, ∝ i is the weight value corresponding to the image data i.

[0091] like Figure 2 As shown, this embodiment also discloses a method for digitally displaying the measured value of an optical interference type methane detector, using the above-mentioned digital display system for the measured value of an optical interference type methane detector, comprising the following steps:

[0092] S1. Capturing images of interference fringes containing methane information formed based on a preset light interference strategy to form corresponding image data;

[0093] S2, performing preprocessing operation on the formed image data;

[0094] S3, extracting key features of interference fringes from the image data based on the image data after the preprocessing operation and based on a preset feature extraction strategy; the key features include fringe spacing, fringe brightness change, and phase information;

[0095] S4. According to the key features of the extracted interference fringes and based on a pre-set methane calculation model, the corresponding methane concentration is calculated, and the calculated methane concentration is sent to the user end for visual display.

[0096] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is described too much here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field of the invention before the application date or priority date, can know all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The protection scope required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A digital display system for measuring values ​​of an optical interference methane detector, characterized in that: Including server and user side; The server includes: An image acquisition module, used to acquire images of interference fringes containing methane information formed based on a preset light interference strategy to form corresponding image data; A preprocessing module, used for performing preprocessing operations on the formed image data; A feature extraction module is used to extract key features of interference fringes from image data based on the image data after preprocessing operations and based on a preset feature extraction strategy; the key features include fringe spacing, fringe brightness change, and phase information; The calculation module is used to calculate the corresponding methane concentration according to the key features of the extracted interference fringes based on a pre-set methane calculation model, and send the calculated methane concentration to the user end for visual display.

2. The optical interference methane detector measurement value digital display system according to claim 1, characterized in that: The preset light interference strategy is: Using a stable light source to emit monochromatic light of a specific wavelength; the specific wavelength is selected to be a wavelength at which methane has a strong absorption characteristic; Based on the monochromatic light of a specific wavelength emitted by a light source, the light beam corresponding to the monochromatic light is divided into two paths by a beam splitter, one of which is used as a reference path, which passes through air gas without methane, and the other is used as a measurement path, which passes through a sample gas containing methane; the light beams on the two paths are re-merged at the merging point after passing through their respective paths, at which time the light waves interfere with each other to form interference fringes.

3. The optical interference methane detector measurement value digital display system according to claim 2, characterized in that: The preprocessing module comprises: A conversion and recognition module, used to convert the formed image data into a corresponding grayscale image, and identify the black stripe line spectrum to be identified in the grayscale image based on a preset segmentation pixel threshold; The morphological processing module is used to connect the scale areas divided by the scale lines and the spectrum lines in the black stripe line spectrum to be identified through the expansion strategy preset in the morphology according to the identified black stripe line spectrum to be identified, so as to form a coherent scale area; The contour detection module is used to perform Hough transformation on the four sides of the rectangular outer contour of the ruler area according to the formed coherent ruler area, and fit the corresponding outer contour of the ruler area; The rotation module is used to determine the direction of the ruler area after fitting the outer contour, and rotate the corresponding ruler area to a horizontal position to form image data after preprocessing operation.

4. The optical interference methane detector measurement value digital display system according to claim 3, characterized in that: The feature extraction strategy includes a first extraction strategy; the first extraction strategy includes the following steps: According to the image data after the preprocessing operation, the image data is converted from the spatial domain to the frequency domain through Fourier transform, and the corresponding frequency spectrum is obtained; Normalize and smooth the acquired spectrum; Perform peak recognition on the processed spectrum to identify the positions corresponding to each peak in the frequency domain; According to the positions of the identified peaks in the frequency domain, the fringe spacing between the peaks is calculated based on a preset fringe spacing calculation formula; The preset stripe spacing calculation formula is: Where d is the fringe spacing between corresponding peaks, (u2, v2) is the position of one of the peaks in the frequency domain, and (u1, v1) is the position of the other peak in the frequency domain.

5. The optical interference methane measuring device measurement value digital display system according to claim 4, characterized in that: The server also includes: A historical data acquisition module is used to obtain historical fringe spacing, historical fringe brightness changes, historical phase information and corresponding historical methane concentrations corresponding to historical image data from a historical database, and divide the corresponding data into a training set and a validation set; Model building module, used to build the corresponding methane calculation model; A training module is used to input the historical fringe spacing, historical fringe brightness changes, and historical phase information in the training set as input data into the methane calculation model, and use the historical methane concentration as output data to train the methane calculation model; A verification module is used to input the historical fringe spacing, historical fringe brightness change, and historical phase information in the verification set as input data into the trained methane calculation model after each training of the methane calculation model is completed, output the corresponding predicted methane concentration, and calculate the corresponding prediction error value based on the predicted methane concentration and the historical methane concentration corresponding to the verification set based on a preset prediction error value calculation formula, and judge whether the prediction error value is less than a preset error threshold. If so, the trained methane calculation model is judged to be a valid model, otherwise the trained methane calculation model is an invalid model, and the training module is continued to be executed to retrain the methane calculation model; The prediction error value calculation formula is: Where W is the prediction error value, y i is the predicted methane concentration corresponding to image data i, is the historical methane concentration corresponding to the validation set image data i, ∝ is the preset weight value, ∝ i is the weight value corresponding to the image data i.

6. A method for digitally displaying the measured value of an optical interference type methane detector, using a digital display system for the measured value of an optical interference type methane detector according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Capturing images of interference fringes containing methane information formed based on a preset light interference strategy to form corresponding image data; S2, performing preprocessing operation on the formed image data; S3, extracting key features of interference fringes from the image data based on the image data after the preprocessing operation and based on a preset feature extraction strategy; The key features include fringe spacing, fringe brightness variation, and phase information; S4. According to the key features of the extracted interference fringes and based on a pre-set methane calculation model, the corresponding methane concentration is calculated, and the calculated methane concentration is sent to the user end for visual display.

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