CN211877766U - Water turbidity measuring device based on infrared camera shooting - Google Patents

Abstract

The utility model belongs to the technical field of the water turbidity is measured, a water turbidity measuring device based on infrared camera is disclosed, the computer passes through USB and is connected with two infrared cameras, installs black PVC pipe on the infrared camera, and in black PVC pipe embedding sample groove, infrared light source installed the offside at an infrared camera, and camera, PVC pipe and infrared light source are at the coplanar. The two infrared cameras are respectively arranged at 180 degrees opposite to the infrared light source and are vertical to the infrared light source by 90 degrees. The infrared camera is powered and connected to the upper computer through a USB. The utility model discloses to the measurement of specific water sample, and the result of commercial turbidimeter have the uniformity, have verified the feasibility of this method, can the accurate measurement 0-1000 NTU's water turbidity. And commercial turbidimeter contrast standard solution, the utility model discloses higher accuracy has. Can replace the traditional optical turbidity measuring method and simplify the design of the turbidity meter.

Description

Water turbidity measuring device based on infrared camera shooting

Technical Field

The utility model belongs to the technical field of the water turbidity is measured, especially, relate to a water turbidity measuring device based on infrared camera shooting.

Background

Currently, the closest prior art: a method for detecting the turbidity of a water body by a water body turbidity detection device based on an underwater observation network comprises the steps of carrying out image enhancement processing on an image shot by a color CCD camera by using a computer, carrying out median filtering and noise reduction to remove pulse noise, carrying out average noise reduction to remove random noise, and calculating the RGB value of the processed image; and taking the turbidity value of the turbid liquid as an abscissa and the difference value between the B value and the G value of the image as an ordinate, and obtaining a relational expression between the turbidity and the B-G value of the image according to an image fitting curve. Due to the influence of color, especially the measurement of colored actual water samples, the relationship between turbidity and RGB values is complex and there is no definite correspondence. And the picture of the ordinary water sample is close to the gray picture, so the B and G values are relatively close, the difference between B and G is very small, unless the image is blue because of the camera, when the method is used for measuring the turbidity, the influence of the color of the water body is large, and the accurate reading of the measurement is very low. The relatively close technology in the literature is to shoot a picture of a plastic bottled water sample by using a high-definition camera and to characterize the water samples with different turbidity by using an image processing technology. The technology has large error, is similar to the technology of a turbidimetric method, and not only is a bottled water sample photographed, but also the surrounding environment of the bottle body is photographed in the measuring process. Meanwhile, the light source has a large influence on the picture characteristics, and is not suitable for quantitative measurement.

Turbidity is the degree of turbidity in water, which is expressed as the degree of obstruction of light transmission by suspended matter in the water. The water contains suspended substances and colloidal substances such as soil, dust, fine organic matters, zooplankton and other microorganisms, and the like, so that the water can show turbidity. The turbidity of water is the obstruction degree of suspended matters, colloidal substances and microorganism impurities with different sizes, specific gravities and shapes in water to the light transmission. The magnitude of turbidity is related not only to the particulate matter in the water body, but also to its particle size, shape and surface area. The liquid turbidity measurement has wide application in various industries and departments of water supply, wine making, pharmacy, environmental protection, health and epidemic prevention and the like. In the aspect of water quality monitoring, turbidity is an important parameter for characterizing water quality and is also one of important parameters for evaluating the quality of the factory water. The measurement of turbidity plays an important role and significance in the turbidity control of industrial water and drinking water in daily life.

At present, the measurement method of the turbidity of water is based on an optical method, and comprises a visual turbidimetry method, a transmission light method, a scattering light method and an integrating sphere method (scattering and transmission method), wherein the visual turbidimetry method has poor accuracy and is only suitable for roughly judging the turbidity of water. The difference between the transmitted light method and the scattered light method is mainly the angle of the photodetectors with respect to the incident light and the number of photodetectors. The angle of the detector has a great influence on the measurement range of turbidity and the sensitivity of measurement.

In the prior art, a turbidity measurement principle based on a transmission light method is adopted, the turbidity is measured by adopting transmission light, parallel light beams emitted from a light source are emitted into a sample, turbid components in the sample attenuate light intensity, and a detector detects the attenuated light intensity. The detector's attenuation detection angle is 180 ° relative to the incident light, and measures the intensity of the incident light after it has been scattered and absorbed, but this angle measurement is susceptible to color interference. The degree of light intensity attenuation as a function of the turbidity of the sample is expressed by the following equation.

I_T＝I₀e^-kdl

In the formula: i is_T: intensity of transmitted light, I₀: incident light intensity, k: proportionality constant, d: turbidity, l: penetration depth.

The second prior art is based on the principle of measuring turbidity by a scattered light method, wherein the turbidity is measured by the scattered light method, and when a light beam emitted by a light source passes through a solution, part of the light passes through the solutionAbsorbed and scattered and another part penetrates the solution. Nephelometers typically detect 90 ° scattered light. The scattering method has good sensitivity to particles with different sizes, and when the diameter of the particle is smaller than the wavelength of incident light, the intensity I of the scattered light in the direction of 90 degrees with the incident light_SThe relationship with the concentration n of the particles in the sample corresponds to the rayleigh formula, as shown in formula (2):

I_S＝I₀kNV²/λ⁴

in the formula: i is_S: intensity of scattered light, I₀: incident light intensity, k: proportionality constant, N: number of particles per unit volume, V: volume of the microparticles, λ: the wavelength of the incident light. It can be seen from the formula that theoretically the scattered light intensity is exactly directly related to the suspended particle concentration, but in actual measurement the situation is different. During the measurement of turbidity with low suspended particle concentration, because the number of suspended particles is small, the interference of particles to scattered light is very limited, the scattered light intensity and the suspended particle concentration are basically in a linear relation, the turbidity measurement can be quantitatively analyzed in the range, and the linear relation is best in the turbidity range of 0-100 NTU. For samples with higher concentrations of suspended particles (greater than 100NTU), multiple scattering of light between particles occurs and the linear relationship between scattered light intensity and suspended particle concentration is disturbed. Nephelometer manufacturers design nephelometers that use scattering light methods to scale according to a linear relationship, so scattering light nephelometers are only suitable for measuring lower turbidity, while transmission light nephelometers can measure higher turbidity.

The third prior art is based on the measurement principle of the transmission scattering ratio method, and in addition, an improved turbidity measurement method, which is called an integrating sphere type turbidity measurement method, is provided, and the correlation curve of the scattered light intensity and the turbidity is corrected. The principle is that the transmitted light and the 90-degree scattered light are compared and detected, and two detectors are used for measuring the turbidity of the liquid. One primary detector is at a 90 ° angle to the incident light for measuring the intensity of scattered light, and the other detector is at a 180 ° angle to the incident light for measuring the intensity of transmitted light. Because the optical path length is the same when the transmission light and the scattered light are measured, the influence of the water sample chromaticity and the light source change on the turbidity is the same, the method can remove partial interference and improve the sensitivity. However, the ratio of the scattered light to the transmitted light intensity is not strictly linear, but rather has an approximately linear relationship over a range of turbidity.

In summary, the conventional turbidity measuring methods are all based on photoelectric detection methods, and optical paths, photoelectric detection circuits, signal amplification and processing circuits, analog-to-digital conversion circuits, and the like need to be designed. The structure is complicated, and only professional companies can design and produce the product.

In summary, the problems of the prior art are as follows:

(1) the attenuation detection angle of the detector in the prior art is 180 degrees relative to incident light, the light intensity of the incident light after being scattered and absorbed is measured, but when a low-turbidity water sample is measured, most of the light is directly transmitted, and the change of the transmitted light caused by small turbidity change is quite small. The change rate is very low, the requirements on the resolution and stability of a photoelectric receiving and amplifying device are very high, so that the transmission light method is not suitable for measuring low turbidity, and impurities and particles with high concentration in a water sample can enable the attenuation of transmission light signals to be more obvious, and the method is suitable for measuring high-turbidity water samples. And the measurement is easily interfered by color, so that different light absorptions of the water sample are different, and a larger measurement error occurs.

(2) In the second prior art, in the scattered light type turbidity measuring method, when the turbidity of the liquid exceeds a limit (more than 100NTU), multiple scattering phenomena occur, so that the scattered light intensity is rapidly reduced, the scattered light intensity cannot correctly reflect the turbidity value of the liquid sample, and the linear relation between the scattered light intensity and the suspended particle concentration is interfered, so that the scattered light type turbidity measuring method is mainly used for low-turbidity and medium-turbidity liquids.

(3) The ratio of the three scattered light and the transmitted light in the prior art is not a strict linear relation, which is caused by multiple scattering of the light by particles in water, and only has an approximately linear relation in a certain turbidity range, so that the measurement range of the turbidity has certain limitation.

(4) The existing turbidity measuring method is based on that the structure of photoelectric detection equipment is complex, and can only be designed and produced by professional companies.

The difficulty of solving the technical problems is as follows: when the transmitted light method is used for measuring a low-turbidity sample, the solution refractive index is small, and the attenuation signal of light intensity is extremely small. If a more sophisticated photodetection system is required to determine the attenuation signal for this very small portion, the production cost will rise exponentially. When a scattered light method is used for measuring a high-turbidity sample, the sample is always influenced by multiple scattering of light, and a better method is to use a transmitted light calibration curve. However, the transmittance-scattering ratio method has an approximately linear relationship only in a certain range, and the measurement range is necessarily affected. Photoelectric detection can only measure light intensity, and solution color is difficult to distinguish.

The significance of solving the technical problems is as follows: the utility model discloses use infrared camera technical analysis turbidity solution image, the formation of image result of infrared camera shooting is grey level image, the interference of water colourity has been avoided, use image colour component to draw technique and colour space conversion technique, a plurality of colour components and turbid relation have been contrasted, especially water luminance L and turbid relation correspondence is very high, the influence of colourity has thoroughly been removed, with the help of the computing power of curve fitting technique and computer, can solve turbidity and colour component accurate measurement under the nonlinear relation. Therefore adopt the utility model discloses can keep fine sensitivity to the turbidity sample of full range, promote turbidity measuring accuracy, increase measuring scope improves measuring speed, simplifies measuring equipment, reduces the manufacturing cost of instrument.

SUMMERY OF THE UTILITY MODEL

Problem to prior art existence, the utility model provides a water turbidity measuring device based on infrared camera shooting.

The utility model discloses a realize like this, a water turbidity measuring device based on infrared camera shooting, water turbidity measuring device based on infrared camera shooting includes: the device comprises a computer, an infrared camera, a black PVC pipe, a sample tank and an infrared light source;

the computer is connected with the two infrared cameras through a USB, the black PVC pipe is installed on each infrared camera, the black PVC pipe is embedded into the sample groove, and the infrared light source is installed on the opposite side of one infrared camera.

Furthermore, the number of the infrared cameras is two, and the two infrared cameras are respectively arranged at 180 degrees opposite to the infrared light source and are perpendicular to the infrared light source for 90 degrees; the infrared camera is powered and connected to the upper computer through a USB.

To sum up, the utility model discloses an advantage and positive effect do: the infrared camera type filters visible light through installing 850 nm's narrowband filter additional in front of the camera lens, and the light of wavelength about only 850nm can be acquireed by camera sensitization chip, combines the infrared light source of 850nm, can filter the chromaticity interference that the sample brought. The infrared light is transmitted or scattered by the turbidity solution to form an image without color, the obtained RGB color components are relatively close, and after the RGB color components are converted into Lab color components through a color space, the L value can reflect the turbidity value of water better. The photosensitive element of the digital camera is a semiconductor element for recording light variation, and each pixel of the photosensitive element is equivalent to a photoelectric detection element. The digital camera has a perfect optical path system, and the integrated signal processing component can replace a photoelectric detection circuit, a signal amplification and processing circuit and an analog-to-digital conversion circuit. When the digital camera shoots the turbidity solution image, the information related to the turbidity is stored in the image, and the turbidity value is obtained through image processing.

The utility model discloses a 850nm LED 0.5W is as infrared light source, under the drive of invariable light intensity control circuit, and the infrared light passes through turbidity solution. And respectively acquiring solution images of an infrared light source after scattering and transmission through the turbidity solution by using an infrared camera to obtain an average RGB value of 400 pixel points in a central area of the corresponding image, and converting the average RGB value into a Lab value. And performing data fitting on different turbidities and corresponding values of R, G, B, L, a and B in a scattering, transmission and integrating sphere mode to obtain a functional relation between the turbidity value and the corresponding color component. And the fitted functional relation is used for measuring the turbidity of the standard turbidity solution and the actual water sample and is compared by a commercial turbidimeter. The results show that the method has higher accuracy for the measurement of the standard solution. The method has consistency with the result of a commercial turbidimeter for the measurement of a specific water sample, verifies the feasibility of the method, and can accurately measure the water turbidity of 0-1000 NTU. Therefore, the water turbidity measurement based on the infrared camera and the image processing technology provides a new idea for turbidity measurement, can replace the traditional optical turbidity measurement method, and simplifies the design of the turbidity meter.

Drawings

Fig. 1 is a schematic structural diagram of a water turbidity measuring device based on infrared camera shooting provided by an embodiment of the present invention;

in the figure: 1. a computer; 2. an infrared camera; 3. a black PVC pipe; 4. a sample tank; 5. an infrared light source; 6. and (3) sampling.

Fig. 2 is a graph of transmittance scattering G2' values and haze provided by embodiments of the present invention.

FIG. 3 shows a scattering L provided by an embodiment of the present invention₁a₁b₁Graph relating to turbidity.

FIG. 4 shows a transmission L provided by an embodiment of the present invention₂a₂b₂Graph relating to turbidity.

FIG. 5 shows a scattering R provided by an embodiment of the present invention₁G₁B₁And turbidity.

FIG. 6 shows a transmission R provided by an embodiment of the present invention₂G₂B₂And turbidity.

FIG. 7 shows a scattering ratio transmission L according to an embodiment of the present invention₁`a<sub>1</sub>`b₁Plot of the relation of the "turbidity" to turbidity.

FIG. 8 shows transmittance scattering L according to an embodiment of the present invention₂`a<sub>2</sub>`b₂Plot of the relation of the "turbidity" to turbidity.

FIG. 9 shows a scattering ratio transmission R provided by an embodiment of the present invention₁`G<sub>1</sub>`B₁Plot of the relationship between the "and turbidity".

FIG. 10 shows transmittance scattering R according to an embodiment of the present invention₂`G<sub>2</sub>`B₂Plot of the relationship between the "and turbidity".

FIG. 11 shows a scattering L provided by an embodiment of the present invention₁And turbidity profiles.

FIG. 12 shows the present inventionExamples provide a transmission L₂And turbidity profiles.

Fig. 13 shows a scattering R provided by an embodiment of the present invention₁And turbidity profiles.

FIG. 14 shows a transmission G provided by an embodiment of the present invention₂And turbidity profiles.

FIG. 15 shows a scattering ratio transmission lower L according to an embodiment of the present invention₁Plot of the "value and turbidity.

Fig. 16 shows transmittance scattering L provided by an embodiment of the present invention₂Plot of the "value and turbidity.

FIG. 17 shows the scattering ratio in transmission, R₁Plot of the "value and turbidity.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The utility model discloses use infrared camera to measure turbidity, acquire the RGB value (red green blue) of solution, obtain the Lab value that solution corresponds through the color space conversion (L represents the infrared light and passes through behind the solution, the transmitted light image that obtains with infrared camera or the luminance of scattered light image), the relation between mainly considering solution turbidity and the luminance L, uses L value survey turbidity.

The technical solution of the present invention will be described in detail with reference to the accompanying drawings.

As shown in fig. 1, the embodiment of the utility model provides a water turbidity measuring device based on infrared camera shooting includes: computer 1, infrared camera 2, black PVC pipe 3, sample cell 4, infrared light source 5, sample 6.

Computer 1 is connected with infrared camera 2 through USB, installs black PVC pipe 3 on the infrared camera 2, and black PVC pipe 3 imbeds in sample cell 4, and two infrared cameras become the angle of 90 degrees, and infrared light source 5 installs the offside at an infrared camera 2, and sample 6 is put into in sample cell 4.

The embodiment of the utility model provides a water turbidity measurement method based on infrared camera includes: the method comprises the steps of respectively obtaining images of transmitted light and scattered light after light passes through a turbidity solution by using an infrared camera, obtaining RGB data of the images through image processing, changing the RGB data to a Lab color space from the RGB space, and then respectively obtaining Lab values of the images. By fitting the relation between the series turbidity and the corresponding R, G, B, L, a and B values in the scattering, transmission and ratio (scattering + transmission) modes, the relation between the turbidity value and the corresponding color component is obtained and used for measuring the actual water sample, and the practical turbidity value is compared with the data of a commercial turbidity meter to verify the feasibility of measuring the turbidity by the method.

The technical solution of the present invention will be further described with reference to the accompanying drawings.

As shown in fig. 1, the infrared light source 5 uses an 850nm, 0.5W LED, and adopts a constant current driving mode, and supplies power through the USB of the infrared camera 2, and adopts a constant current circuit composed of an operational amplifier, a reference voltage and a transistor to drive the LED, and the current is adjustable, and the working current is about 15 mA. Two infrared cameras 2 are respectively in the opposite (180 °) and perpendicular (90 °) direction of infrared light source 5, and for better adjustment focal length, use black PVC pipe 3 to connect infrared camera 2 and sample cell 4. The infrared camera 2 is powered by the USB and connected to the upper computer, and the acquired image is sent to the computer for further processing to obtain required experimental data. When the turbidity of the water sample is measured, a closed space can be formed between the black cover of the sample to be measured 6 and the sample groove 4, and the interference of other light sources is effectively avoided. FIG. 2 is a schematic diagram of the experimental apparatus.

The digital camera used for measurement is a commercially available common infrared camera, and comprises an optical lens, a CMOS image sensor, a control chip and the like, the model is Kingcent AR0130, and the maximum resolution of the camera is 1280 x 960. A850 nm narrow-band optical filter is additionally arranged on the lens, the focal length is 3.6mm, and the focal length can be manually adjusted, so that the turbidity solution can be imaged clearly. The camera may also use a fixed focal length if in production. Whatever the infrared camera, the image of the turbid liquid must be clear. In addition, the camera is required to prohibit automatic adjustment parameters such as automatic exposure and automatic brightness, and the manually adjusted parameters such as brightness, exposure and contrast can be automatically saved in the system, so that the consistency of the parameters in the measurement process is ensured. These characteristics enable the data to reflect differences in the range from the lowest turbidity to the highest turbidity.

The CMOS photosensitive element used for the digital camera is a semiconductor element used for recording light change. Each pixel of the camera corresponds to a photo-detection element. When light emitted by the light source passes through the turbidity solution and passes through the 850nm optical filter of the camera lens, the light is projected onto the image sensor for photoelectric conversion, and after passing through the signal processing component integrated with the camera, the light is transmitted to the upper computer software through the USB port for processing. The camera integrated signal processing component can replace an analog-to-digital conversion circuit and a signal processing circuit of the turbidity meter. The design process of a photoelectric detection circuit, a signal processing circuit, a digital-to-analog conversion circuit and a display circuit is avoided, and the turbidity measurement process can be visualized.

The technical effects of the present invention will be described in detail with reference to the experiments.

1. In the experiment, the RGB values of the transmitted light and the scattered light corresponding to different turbidity and the Lab value after conversion were measured, respectively. And randomly selecting 5 groups of experimental data of scattering and transmission, and averaging to obtain a group of average data of scattering and transmission. In the experiment, 30 standard solutions were prepared, including 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000 NTU.

2. Experimental data and analysis

FIG. 3 is a graph showing haze and L in a 90 ℃ scattering mode₁a₁b₁The relationship between the values, FIG. 4 is the haze and L in the transmission mode₂a₂b₂The relationship between the values. It is seen that the correspondence between the L value and the turbidity can be used to measure turbidity, while the a and b values may have several turbidities corresponding to them. It is clear that the values of a or b do not have a one-to-one correspondence to turbidity, and that the values of a and b cannot be used to obtain a unique turbidity. Theory of thingsTheoretically, the transmitted light intensity is exponentially negative with the turbidity. However, when the transmitted light is measured using the camera of the present invention, the relationship between the luminance L and the turbidity is approximately linear. The reason for this is that the brightness L obtained by the imaging method is different from the light intensity obtained by the photocell of the turbidimeter. When L is converted from RGB color space to Lab color space, the cube root is implemented using the standard functions exp (exponential) and ln (natural logarithm). The luminance is equivalent to a conversion from exponential space to logarithmic space, so the exponential relationship is approximately linear.

FIG. 5 is a graph showing haze and R in a 90 ℃ scattering mode₁G₁B₁The relationship between the values, FIG. 6 is the haze and R in transmission mode₂G₂B₂The relationship between the values. The G and R values and haze trends are consistent in both the scattering and transmission modes. However, the B value does not correspond to the turbidity in the scattering mode, and the B value is very low in the transmittance mode when the concentration is low. This is because the RGB values are related to the adjustment of the camera parameters, which is the case when the image is bluish. If the image is reddish, the R value is similar to the B value for a bluish image.

Partial influences of light refraction, turbid solution color, LED light source aging and instability on measurement can be eliminated by utilizing the ratio of scattering data to transmission data. The ratio of L, a and b is recorded as L ', a ' and b '. FIG. 7 shows L in a scattering ratio transmission mode₁`a<sub>1</sub>`b₁Relationship between the value and haze, FIG. 8 is the transmission scattering mode L₂`a<sub>2</sub>`b₂Relation between the value and turbidity. In the ratio mode, the effect based on the value of L 'is best, and the value of L' has high discrimination under turbidity change no matter scattering ratio transmission or transmittance scattering. The discrimination between the color components a ', b' and turbidity is low and cannot be used for turbidity measurements.

R, G, B are designated as R ', G ', B ', and FIG. 9 shows R in the scattering ratio transmission mode₁`G<sub>1</sub>`B₁Relationship between the value and haze, FIG. 10 is R in the transmission scattering mode₂`G<sub>2</sub>`B₂Relation between the value and turbidity. R in transmittance scattering mode₂`G<sub>2</sub>`B₂"high sensitivity to low concentrations, and conversely, lower sensitivity to medium and high concentrations. Scattering ratio transmission mode R₁`G<sub>1</sub>`B₁"sensitivity to high concentrations is higher, and sensitivity to medium and low concentrations is lower.

3. Results of fitting to L, R and G values

Through experimental data analysis, the trend of change between the L value, the R value and the G value and the turbidity presents better monotonicity, so the L value, the R value and the G value are selected for turbidity measurement. The formula for fitting the curve and the adjusted decision coefficients are given in the graph, as are the fitting subjects and the fitting models in the legend at the upper right of the graph.

3.1 analysis of correspondence between L value and turbidity

The values of L in both the scattering and transmission modes are plotted against haze in fig. 11 and 12. Analyzing the correlation between RGB value and turbidity value in transmission and scattering modes, respectively fitting the data of R value and G value, R value in scattering mode₁Value and G in transmission mode₂The fitting correlation of the values to turbidity is higher, FIG. 13 is R in the scattering mode₁Fitted curve between values and turbidity, FIG. 14 is G in transmission mode₂Fitted curve between values and turbidity.

FIG. 15 shows the scattering ratio transmission mode L₁Fitting curve of the value of the ` value to turbidity, FIG. 16 is the value of L in the transmission scattering mode₂Fitting curve of the value of the "to turbidity.

When the R ' G ' B ' value is in the fitting ratio mode, the R ' value and the G ' value are respectively fitted, and the result shows that the R ' value and the G ' value are in the scattering ratio transmission mode₁G in scattering mode of' value and transmittance₂The fit correlation of the values is higher. FIG. 17 shows R in a scattering ratio transmission mode₁Fitted curves of "value and haze, FIG. 2 is G for transmittance scattering mode₂Fitted curve of the values and turbidity.

The fitting results of the above eight measurements are shown in table 1. To clearly explain the effects of variables and random errors, the differences of the data points and their corresponding locations on the regression line are statistically referred to as residuals (mean square errors), and the sum of the mean square errors is referred to as the sum of the squared residuals, representing the effect of random errors. The adjusted r-square (adj. r2) cancels out the effect of the sample size on r 2. The larger the value of 0 to 1, the better. Add a feature variable, if the feature is meaningful, then adj. r2 will increase, if the feature is redundant, then adj. r2 will decrease.

Table 1 comparison of fitting results for different measurement modes.

3.2 comparison with turbidimeter verification, above analysis of experimental data, eight measurement modes can be used to measure turbidity. We verified the accuracy and reliability of these methods by measuring standard solutions and actual water samples and then comparing these results with those of a commercial turbidimeter. The turbidity meter 1 is model No. WGZ-1B, and the measuring range is 0-200 NTU; the range of the turbidimeter 2 is 0 to 1000NTU, and the type is WGZ to 2000. The range of the utility model is 0-1000 NTU.

3.3 the accuracy and error of the method were calculated from the measurements on the standard turbidity solutions. The basic error of the turbidimeter 1 and turbidimeter 2 is provided by the respective specifications. The utility model discloses according to the difference between measured data and the corresponding standard turbidity, according to the maximum integer (5 or 10) upper limit calculation error. Adopt the utility model discloses survey 10, 20, 30, 40, 50, 60, 80, 100, 150, 200 NTU's low turbidity experimental group to compare with turbidimeter 1, surveyed 50, 100, 200, 300, 400, 500, 600, 700, 800, 900 NTU's high concentration experimental group, and compared with turbidimeter 2. Independent sample t-tests were performed on the turbidity data for the 18 sets of standard solutions, with a single-tailed significance level of greater than 0.05 for each set, indicating no significant difference in the data. The two-tailed significance levels are shown in table 2.

TABLE 2 two-tailed significance levels

Combined with two experimental groupsConcentration data and a two-tailed significance level, the result of measuring the turbidity of the solution by using the L value is close to that of a standard solution, and the measurement precision is higher than that of a turbidity meter 1 and a turbidity meter 2. Therefore, we propose to measure turbidity using the luminance L value. For the measurement of high turbidity solutions, all the methods listed in table 1 are more accurate than turbidimeter 1 and turbidimeter 2. However, for low turbidity solutions, the scattering ratio is R in transmission mode₁"values cannot be used to measure turbidity, G in transmission mode, for solutions below 30NTU₂Value and transmittance of G in scattering mode₂The measurement accuracy of the value of is not as good as that of turbidimeter 1 and turbidimeter 2, so these three methods are no longer used in the following measurements. In the scattering mode, the R value has high accuracy on the measurement of a low-turbidity solution, and can be used for the measurement of turbidity. In summary, we propose five methods of using the luminance L and the color R in the scattering mode, the luminance L in the transmission mode, and the scattering transmittance and the transmission transmittance based on the luminance L.

3.4 actual water sample comparison measurement

10 sample solutions were taken from the production and domestic water sources, mainly local rivers, industrial wastewater and process water. 10 sample solutions are randomly prepared by using standard turbidity water, the existing turbid solution is mixed with distilled water according to any proportion, and the turbidity value is controlled within the range of turbidity 1 measurement range. The data determined for these 20 water samples and the data determined for the turbidimeters 1 and 2 were subjected to one-way anova using 5 measurement methods.

Given the significance level α, if the probability p value is greater than α, the original assumption should be accepted that our 5 measurements do not differ significantly from the turbidimeter measured concentration. The results of the one-way anova for each set of data are shown in table 3, with a significance level α of 0.05.

TABLE 3 results of one-way ANOVA of each group of data

The probability P values of the five groups of data are all larger than alpha, so that the five groups of data have no obvious difference with the data of the turbidimeter 1 and the turbidimeter 2, and the practicability of the new infrared digital camera device measuring result is explained. .

The utility model provides a turbidity measuring method based on infrared camera has designed turbidity measuring device and image acquisition software. The transmission and scattering images of infrared light after penetrating through solutions with different turbidities are obtained through the camera, and the fitting relation and the fitting correlation of the turbidities to different color components in the modes of transmission, scattering and ratio are obtained respectively. The feasibility of measuring turbidity using 5 modes of brightness L and color R in the scattering mode, brightness L in the transmission mode, and scattering transmittance and transmission scatter based on brightness L was verified. Compared with a commercial turbidimeter, the measurement modes are verified, and compared with the measurement of a standard solution, the method has higher accuracy compared with a turbidimeter; the practical applicability of these methods was verified for the measurement of specific water samples, consistent with the results of the turbidimeter. It is recommended to use the luminance L value for turbidity measurements, in particular the L value for transmittance scattering. A single camera in scatter or transmission mode, or dual cameras in ratio mode may be selected as desired. For colorless or high turbidity solutions, the value of L in transmission mode can be chosen. For solution measurements with low turbidity, either the L or R values in the scattering mode can be chosen. The L value in the ratio mode of the two infrared cameras can be used to measure colored solutions or scenes with such high sensitivity requirements. The infrared camera is adopted to replace an optical detection system, so that the design cost is reduced, and the measurement precision is improved. The method is suitable for quantitative turbidity sensors and can also be applied to other infrared measurement fields.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

The utility model discloses and the measuring result of two commercial turbidimeters to specific water sample.

Claims (3)

1. The utility model provides a water turbidity measuring device based on infrared camera shooting, a serial communication port, water turbidity measuring device based on infrared camera shooting is provided with:

a computer;

the computer is connected with the two infrared cameras through a USB, the black PVC pipe is installed on each infrared camera, the black PVC pipe is embedded into the sample groove, the infrared light source is installed on the opposite side of one infrared camera, and the camera, the PVC pipe and the infrared light source are on the same plane.

2. The apparatus of claim 1, wherein the number of the infrared cameras is two, and the two infrared cameras are respectively opposite to the infrared light source by 180 degrees and perpendicular to the infrared light source by 90 degrees.

3. The water turbidity measurement device based on infrared camera shooting as claimed in claim 1, wherein said infrared camera is powered and connected to an upper computer through USB.

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