CN115201188A - System and method for measuring methylene blue value of machine-made sand based on computer vision - Google Patents

Abstract

The invention relates to the technical field of building material testing, in particular to a system and a method for testing a methylene blue value of machine-made sand based on computer vision, wherein the system comprises a shooting component, an adjusting component and a processing component, and the method comprises the steps of obtaining a shooting methylene blue value test image; dividing a methylene blue value test image into a plurality of color areas with obvious contrast, calculating the areas of the color areas with the color halos and the color areas without the color halos, calculating the radiuses of the color areas with the color halos and the color areas without the color halos by using an area formula, and subtracting the radiuses of the color areas with the color halos and the color areas without the color halos to obtain the color halo width; the method comprises the steps of obtaining the resolution ratio of a methylene blue value test image, converting the sizes of the halo width and the resolution ratio into the number of pixel points with preset halo width, comparing the number of the pixel points with a number threshold, judging that the titration end point of a methylene blue test is successfully identified when the number of the pixel points is larger than the number threshold, and calculating the methylene blue value of a mechanism sand titration result graph. The invention has simple structure, convenient operation and improved efficiency.

Description

Computer vision-based testing system and method for methylene blue value of machine-made sand

technical field

The invention relates to the technical field of building materials testing, in particular to a system and method for testing the methylene blue value of machine-made sand based on computer vision.

Background technique

Machine-made sand is one of the types of fine aggregates used in construction projects. When the content of mud powder in machine-made sand is too high, the water and water reducing agent of fresh concrete will be absorbed too much by mud powder, which will affect the workability of concrete and increase concrete production. Cost, in addition, reduces the mechanical properties and durability of hardened concrete. Methylene blue value (MB value) is an index for judging the relative content of mud powder in fine particles less than 0.075 mm in manufactured sand. Therefore, the MB value of manufactured sand is of great significance for the quality control of manufactured sand and concrete quality.

At present, the MB value of the manufactured sand in the project is detected by the methylene blue test method specified in GB/T14684 "Sand for Construction". After methyl blue, dip a drop of the suspension on the filter paper with a glass rod, and observe with the naked eye a stable light blue halo of about 1mm wide that does not disappear around the sediment on the filter paper, and obtain its methylene blue value (MB value) . However, using the human eye recognition method to judge the titration end point and the color halo width is not only inefficient, but also has large subjective errors.

SUMMARY OF THE INVENTION

The present invention is intended to provide a method for testing the methylene blue value of machine-made sand based on computer vision, so as to solve the problems of low test efficiency and large subjective error of the methylene blue value of the existing machine-made sand.

The method for testing the methylene blue value of machine-made sand based on computer vision in this scheme includes the following steps:

Step 1, obtaining the methylene blue value test image of the machine-made sand titration test result obtained by shooting;

Step 2, according to the preset color model, the methylene blue value test image is divided into a variety of color areas with obvious contrast, and the area of the color area with halo and the color area without halo in the color area is calculated, and the color area is calculated according to the area formula. The radius corresponding to the area of the halo color area and the area without the halo color area, and the difference between the radii of the halo color area and the area without the halo color area is used to obtain the halo width;

Step 3: Obtain the resolution of the methylene blue value test image, perform size conversion according to the color halo width and resolution, obtain the number of pixels corresponding to the preset color halo width, and compare the number of pixels with the number threshold. When the quantity is greater than the quantity threshold, it is judged that the methylene blue test titration end point is successfully identified, and the methylene blue value of the sand-making titration result graph is calculated to judge whether the methylene blue value is within the preset range, and if so, the methylene blue value meets the requirements .

In order to establish a unified photographing mode of the methylene blue value test image, in the step 1, the camera is fixed on the bracket, the shooting distance between the camera and the machine-made sand titration result graph is adjusted, and the camera signal is connected to the processing component, and the camera is photographed. The methylene blue value image is sent to the processing component, and in step 2 and step 3, the processing component calculates and processes the methylene blue value test image.

In order to accurately calculate the color halo width, in the step 2, by adjusting the hue threshold, saturation threshold and brightness threshold in the preset color model, and using the corresponding relationship between rows, columns and coordinate systems to segment the blue parts of different colors, Divide the methylene blue value test image to form areas of contrasting color.

Wherein, in the step 2, the area with the halo color area and the color area without the halo color area are approximated into a circle for area calculation.

The methylene blue value test system of machine-made sand based on computer vision, including shooting components, adjustment components and processing components;

The photographing component, located on the adjusting component, is used to photograph the methylene blue value test image of the titration test result of the machine-made sand;

The adjustment component is used to adjust the shooting distance between the shooting component and the machine-made sand titration result graph;

The processing component is used to obtain the methylene blue value test image and identify the methylene blue halo, the processing component calculates the number of pixels corresponding to the width of the preset color halo, and the processing component compares the number of pixels with the number threshold. In contrast, when the number of pixel points is greater than the number threshold, the processing component determines that the methylene blue test titration end point is successfully identified, and calculates the methylene blue value of the sand-making titration result graph to determine whether the methylene blue value is within the preset range, If so, the methylene blue value meets the requirements.

In order to adjust the shooting distance accurately and stably, the adjustment component includes an object carrier, a bracket is fixed on the object carrier, and an adjustment seat located above the object carrier is arranged on the bracket, and the camera is fixed on the adjustment seat. The seat faces the side of the load board.

Wherein, the adjusting seat is in the shape of a rectangular body, and a screwing bolt is screwed on the adjusting seat, and the screwing bolt can be pressed against the bracket.

In order to capture the scene with sufficient light to ensure the clarity of the methylene blue value test image, the bracket is provided with an illumination seat located between the object carrier and the camera, the illumination seat is fixed with a ring frame, and the ring An illumination light source is fixed on the shelf.

In order to adjust the brightness of the light when taking pictures to achieve the accuracy of the methylene blue value test results, the illumination light sources are arranged in multiple groups, each group of illumination light sources includes a plurality of lamp beads, and the lamp beads of each group of illumination light sources are evenly nested. The lighting source signal is connected to the processing component, the processing component initially sends a lighting signal to any group of lighting sources, and the processing component sends a lighting signal to a group of lighting sources adjacent to the lighting lighting source when the number of pixels is less than the threshold Light up the signal, and re-acquire the methylene blue value test image for test calculation.

The present invention tests the methylene blue value of machine-made sand by setting a device, has simple structure and convenient operation, greatly saves manpower consumption while improving efficiency, and improves the accuracy of test results.

Description of drawings

Fig. 1 is the flow chart of the methylene blue value test method of machine-made sand based on computer vision one embodiment of the present invention;

Fig. 2 is the methylene blue value test image taken by the computer vision-based machine-made sand methylene blue value test method according to the embodiment of the present invention;

Fig. 3 is the image after segmentation in the method for testing methylene blue value of machine-made sand based on computer vision according to Embodiment 1 of the present invention;

Fig. 4 is the area with color halo (left picture) and the area without color halo (right picture) in the method for testing methylene blue value of machine-made sand based on computer vision in the embodiment of the present invention;

FIG. 5 is a front view of a computer vision-based methylene blue value testing system for machine-made sand according to Embodiment 1 of the present invention.

Detailed ways

The following is further described in detail through specific embodiments.

Reference numerals in the drawings in the description include: a carrier plate 1 , a bracket 2 , an adjustment seat 3 , an illumination seat 4 , a ring frame 5 , a camera 6 , and a screw bolt 7 .

Example 1

The methylene blue value test system for machine-made sand based on computer vision is shown in Figure 5: it includes a photographing component, an adjusting component and a processing component. The photographing component is located on the adjusting component. The value of the test image, the shooting component can be used with the existing industrial camera 6.

The adjusting component is used to adjust the shooting distance between the photographing component and the machine-made sand titration result chart. The adjusting component includes an object carrier 1 , a bracket 2 is welded on the object carrier 1 , and an adjustment seat 3 located above the object carrier 1 is sleeved on the bracket 2 . , the adjustment seat 3 is a rectangular body, and the adjustment seat 3 is screwed with a screw bolt 7 . The screw 7 can be pressed against the bracket 2 , and the camera 6 is fixed and installed on the side of the adjustment base 3 facing the object carrier 1 through screws. The bracket 2 is welded with a lighting seat 4 located between the object carrier 1 and the camera 6 , and a circular ring frame 5 is welded on the side of the lighting seat 4 facing the object carrier 1 , and the ring frame 5 is on the side facing the object carrier 1 . The lighting source is fixedly installed.

The processing component is used to obtain the methylene blue value test image and identify the methylene blue halo. The processing component calculates the number of pixels corresponding to the preset color halo width. The preset color halo width can be set to 1mm. The number is compared with the number threshold, and the number threshold is set to 3.78. When the number of pixels is greater than the number threshold, the processing component determines that the methylene blue test titration end point is successfully identified, and calculates the methylene blue value of the sand-making titration result graph to determine the methylene blue. Whether the blue value is within the preset range, if so, the methylene blue value meets the requirements, and the processing components include the existing PC host and monitor. The existing MatLab software is installed on the processing module.

The methylene blue value test method of machine-made sand based on computer vision, as shown in Figure 1, includes the following steps:

Step 1, fix the camera 6 on the bracket 2, the camera 6 uses an existing industrial camera, adjust the shooting distance between the camera 6 and the machine-made sand titration result graph, connect the camera 6 signal to the processing component, and the camera 6 shoots the methylene chloride. The blue value image is sent to the processing component, and the processing component obtains the methylene blue value test image of the machine-made sand titration test result, and the obtained methylene blue value test image is shown in Figure 2.

Step 2, the calculation and processing of the methylene blue value test image by the processing component, the calculation and processing of the methylene blue value test image by the processing component are carried out by carrying MatLab software, and the calculation and processing of the methylene blue value test image by the processing component The process is to divide the methylene blue value test image into a variety of contrasting color areas according to the preset color model, that is, areas with different blue parts, the preset color model is the HSV color model, and the HSV color model is the H value representing the hue. , S value represents saturation and V value represents brightness. The segmentation principle is: by adjusting the hue threshold, saturation threshold and brightness threshold in the preset color model, the threshold value range is shown in Table 1, and use the row, column and The corresponding relationship of the coordinate system is used to divide the blue parts of different degrees, and the methylene blue value test image is divided to form a color area with obvious contrast. The ranges of the HSV components are: H, 0-180, S, 0-255, V, 0- 255, the corresponding relationship is shown in Table 2, and the segmented image is shown in Figure 3.

Correspondence The function [row,col]=ind2sub(sz,ind) returns the arrays row and col containing the equivalent row and column subscripts corresponding to the linear index ind of a matrix of size sz. To get the linear indices of matrix elements that satisfy certain conditions, use the find function with an output parameter. Then adjust the range of HSV according to the different color thresholds corresponding to the three parameters of HSV, and finally find the pixels in the blue part and the light blue part in the figure.

Approximate the color area with halo and the color area without halo into a circle to calculate the area, use the area formula bwarea to calculate the area of the color area with halo and the area without halo in the color area, and calculate the area with halo color. The area of the color area is 100140 pixels, and the area without the halo color area is 83767 pixels. The halo width is obtained by taking the difference between the radii of the halo color area and the non-halo color area.

Table 1 Threshold value range of HSV

blue yellow White black tone 200-255° 25-55° \ \ saturation 0.4-1 0.4-1 0-0.1 \ brightness 0.3-1 0.3-1 0.9-1 0-0.35

Table 2 Correspondence

DPI (Dots Per Inch) is a unit of measure that refers to the number of sampling, displayable or output dots per inch of length.

Step 3: Obtain the resolution of the methylene blue value test image and adjust the resolution. Because the industrial camera itself supports multiple resolutions, the adjustment resolution is the resolution of the image recognition set in MATLAB, and the resolution is captured by the camera 6. Obtain directly from the image, perform size conversion with resolution and adjusted resolution, and obtain the number of pixels corresponding to the preset color halo width. The preset color halo width can be set to 1mm, or set to other values according to requirements, that is, the light The width of the blue halo is 15.2489 pixels, and the number of pixels is compared with the number threshold. For example, the dpi value of adjusting the resolution to 1024×768 is a constant: 96, then the calculated relationship between millimeters and pixels is also about It is equal to a constant, that is, 1 mm is approximately equal to 3.78 pixels as the number threshold, and the number of pixels in the width of the light blue halo on the methylene blue value test image is calculated. When the number of pixels is greater than the number threshold, the methylene blue test titration end point is judged The identification is successful. After the identification is successful, the methylene blue value of the sand-making titration result graph will be computerized to determine whether the methylene blue value is within the preset range. The preset range is set according to the relevant specifications. For example, the specification requires that the MB value be less than 1.4 , if the calculation result of the MB value is less than 1.4, then the MB value meets the requirements, and the result is output; if the calculation result is greater than 1.4, the MB value does not meet the requirements, and the MB value result is output. The calculation steps of the methylene blue value are: when it is judged that the identification of the methylene blue test titration end point is successful, a dialog box will pop up, and the methylene blue value titration after the final titration is used as the input parameter V. The methylene blue value is calculated, and the preset formula is:

MB=(V/m)×10, where MB is the methylene blue value, in grams per kilogram (g/kg), V is the total amount of methylene blue solution added, in milliliters (mL), m is the mass of the sample, in grams (g), and 10 is the volume of methylene blue solution consumed per kilogram of the test sample converted into the mass of methylene blue.

In this embodiment, by taking a test image of methylene blue value, and performing subsequent identification and calculation with the aid of computer vision and software, MB value judgment and MB value calculation can be intelligently performed, which can improve the judgment efficiency; avoid visual differences due to different people Resulting in wrong subjective judgment; for complicated long-period experiments, it reduces the time in the experiment process, makes the experiment easier to operate and controllable, and improves the accuracy of the experiment.

Embodiment 2

The difference between the machine-made sand methylene blue value test system based on computer vision and the first embodiment is that there are multiple groups of lighting sources, for example, four groups of lighting sources, each group of lighting sources includes multiple lamp beads, and each group is provided with five lamps The lamp beads of each group of lighting sources are nested and evenly distributed, and the four groups of lighting sources are marked as 1 group, 2 groups, 3 groups and 4 groups respectively, and the lamp beads in each group are marked as 1.1, 1.2, 1.3, 1.4, 2.1, 2.2, 2.3, 2.4, 3.1, 3.2, 3.3, 3.4, 4.1, 4.2, 4.3, 4.4, the nested uniform distribution is: 1.1, 2.1, 3.1, 4.1, 1.2, 2.2, 3.2, 4.2, . A group of lighting sources sends lighting signals, and re-acquires the methylene blue value test image for test calculation.

Since the light source in the environment and the surrounding objects may cause errors in the detection results under the interference of the shadow of the ambient light source, when the number of pixels is less than the threshold, a group of lighting sources adjacent to the lit lighting source will be lit. Simultaneously brighten the light intensity from multiple points and increase the concentration of the light. According to the recognition calculation results, the corresponding lighting source is lit, and the brightness of the light when taking pictures is adjusted to achieve the accuracy of the methylene blue value test results.

The above descriptions are only embodiments of the present invention, and common knowledge such as well-known specific structures and characteristics in the solution are not described too much here. It should be pointed out that for those skilled in the art, some modifications and improvements can be made without departing from the structure of the present invention. These should also be regarded as the protection scope of the present invention, and these will not affect the implementation of the present invention. Effectiveness and utility of patents. The scope of protection claimed in this application shall be based on the content of the claims, and the descriptions of the specific implementation manners in the description can be used to interpret the content of the claims.

Claims (9)

1. The machine-made sand methylene blue value testing method based on computer vision is characterized by comprising the following steps of:

step 1, obtaining a methylene blue value test image of a machine-made sand titration test result obtained by shooting;

step 2, segmenting the methylene blue value test image into a plurality of color areas with obvious contrast according to a preset color model, calculating the areas of the areas with and without the halo color areas in the color areas, calculating the corresponding radiuses of the areas with and without the halo color areas according to an area formula, and obtaining the halo width by subtracting the radiuses of the areas with and without the halo color areas;

and 3, obtaining the resolution of the methylene blue value test image, carrying out size conversion according to the halo width and the resolution to obtain the number of pixel points corresponding to the preset halo width, comparing the number of the pixel points with a number threshold, judging that the titration end point of the methylene blue test is successfully identified when the number of the pixel points is greater than the number threshold, calculating the methylene blue value of a mechanism sand titration result diagram, judging whether the methylene blue value is within a preset range, and if so, ensuring that the methylene blue value meets the requirement.

2. The computer vision-based machine-made methylene blue value test method of claim 1, wherein: in the step 1, a camera is fixed on a support, the shooting distance between the camera and a mechanism sand titration result graph is adjusted, a camera signal is connected to a processing assembly, a methylene blue value image is shot by the camera and sent to the processing assembly, and in the step 2 and the step 3, the processing assembly calculates and processes the methylene blue value test image.

3. The computer vision-based machine-made methylene blue value test method of claim 2, wherein: in the step 2, the hue threshold, the saturation threshold and the brightness threshold in the preset color model are adjusted, the blue parts of different colors are segmented by utilizing the corresponding relation of the rows, the columns and the coordinate system, and the methylene blue value test image is segmented to form a color area with obvious contrast.

4. The computer vision-based machine-made methylene blue value test method of claim 3, wherein: in the step 2, the area of the area with the color halo and the area without the color halo are approximately rounded for area calculation.

5. In the mechanism of computer vision sand methylene blue value test system, its characterized in that: the device comprises a shooting component, an adjusting component and a processing component;

the shooting component is positioned on the adjusting component and used for shooting a methylene blue value test image of the mechanism sand titration test result;

the adjusting component is used for adjusting the shooting distance between the shooting component and the mechanism sand titration result graph;

the processing component is used for obtaining a methylene blue value test image and identifying methylene blue halos, the processing component calculates the number of pixel points corresponding to the preset halo width, the processing component compares the number of the pixel points with a number threshold, when the number of the pixel points is larger than the number threshold, the processing component judges that the titration end point identification of the methylene blue test is successful, calculates the methylene blue value of a mechanism sand titration result graph, judges whether the methylene blue value is located in a preset range, and if yes, the methylene blue value meets the requirement.

6. The computer vision based machine-made methylene blue value testing system of claim 5, wherein: the adjusting component comprises an object carrying plate, a support is fixedly arranged on the object carrying plate, an adjusting seat located above the object carrying plate is arranged on the support, and the camera is fixedly arranged on one side of the adjusting seat facing the object carrying plate.

7. The computer vision-based machine-made methylene blue value testing system of claim 6, wherein: the adjusting seat is rectangular, a screwing bolt is spirally matched on the adjusting seat, and the screwing bolt can be abutted against the support.

8. The computer vision-based machine-made methylene blue value testing system of claim 7, wherein: the camera is characterized in that the support is provided with an illumination seat positioned between the object carrying plate and the camera, the illumination seat is fixedly provided with a circular ring frame, and an illumination light source is fixedly arranged on the circular ring frame.

9. The computer vision-based machine-made methylene blue value testing system of claim 8, wherein: the lighting source sets up the multiunit, and every group lighting source includes a plurality of lamp pearls, and every group lighting source's lamp pearl nestification evenly distributed, lighting source signal connection processing subassembly, processing subassembly sends the signal of lighting to arbitrary group lighting source at the beginning, processing subassembly sends the signal of lighting to a set of lighting source adjacent to lighting source has lighted when pixel quantity is less than the threshold value, and reacquires methylene blue value test image and test the calculation.

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