Method and system for measuring water content of paper based on radar backscattering

Abstract

The invention provides a paper moisture content measuring method and system based on radar backscattering, and relates to the technical field of radar measurement, and the method comprises the steps: obtaining a to-be-measured target paper package, and determining the dielectric constant of the target paper package; transmitting a radar signal to the target paper parcel according to a preset angle and a preset frequency point, and receiving a returned radar echo signal; calculating a radar backscattering coefficient based on the dielectric constant of the paper package, the surface roughness, the radar parameter and the radar echo signal; based on the backscattering coefficient, a mathematical model between the backscattering coefficient and the water content in the paper is constructed through a linear regression method, and the mathematical model is solved to achieve measurement and calculation of the water content in the paper parcel. Through signal processing and image display, the moisture content in the paper can be intuitively reflected.

Description

Technical Field

[0001] The present disclosure relates to the field of radar measurement technology, and in particular to a paper moisture content measurement method and system based on radar backscattering. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] The moisture content of paper is one of the key factors affecting the performance and quality of paper. Accurately measuring the moisture content of paper is of great significance during the production, storage and use of paper. Traditional methods for measuring the moisture content of paper have certain limitations, such as slow measurement speed, low accuracy, and damage to paper. In addition to manual methods, microwave technology is also included.

[0004] Existing microwave technology measures moisture content by utilizing the attenuation and phase change of microwave signals when propagating in paper. Water has a high dielectric constant, so changes in moisture content in paper will significantly affect the propagation characteristics of microwave signals. Microwave technology includes two methods: transmission measurement and reflection measurement. Transmission measurement calculates moisture content by detecting the attenuation and phase change of microwaves after passing through paper, which is suitable for thinner paper; reflection measurement infers moisture content by analyzing the characteristics of microwaves after reflection on the surface of paper, which is suitable for scenes with thick or opaque paper. This method has the advantages of non-contact and fast measurement, but it also has some technical disadvantages and problems, such as high requirements for the measurement environment, and factors such as environmental humidity and temperature will interfere with the measurement results; the equipment cost is high and is not suitable for small-scale or low-budget applications; the measurement accuracy may decrease when the thickness or density of paper changes greatly; in addition, the penetration of microwave signals is limited and may not be suitable for specific types of paper or composite materials. Summary of the invention

[0005] In order to solve the above problems, the present disclosure proposes a paper moisture content measurement method and system based on radar backscattering, which selects the optimal operating frequency in a wider frequency range to adapt to different paper types and moisture content measurement requirements. The backscattering coefficient is calculated through the radar echo intensity under different moisture content conditions, and a mathematical model between the backscattering coefficient and the paper moisture content is established, thereby realizing accurate measurement of the paper moisture content.

[0006] According to some embodiments, the present disclosure adopts the following technical solutions:

[0007] The paper moisture content measurement method based on radar backscattering includes:

[0008] Obtain a target paper package to be tested, and determine the dielectric constant of the target paper package;

[0009] Transmitting a radar signal to the target paper bag at a predetermined angle and frequency, and receiving a returned radar echo signal;

[0010] Calculate the radar backscatter coefficient based on the dielectric constant, surface roughness, radar parameters and radar echo signal of the paper package;

[0011] Based on the backscattering coefficient, a mathematical model between the backscattering coefficient and the moisture content of the paper is constructed by the linear regression method, and the mathematical model is solved to realize the measurement and calculation of the moisture content of the paper.

[0012] According to some embodiments, the present disclosure adopts the following technical solutions:

[0013] Paper moisture content measurement system based on radar backscatter, including:

[0014] A preprocessing module, used to obtain a target paper package to be tested and determine the dielectric constant of the target paper package;

[0015] A signal acquisition module, used to transmit a radar signal to the target paper bag at a predetermined angle and frequency point, and receive a returned radar echo signal;

[0016] The model building and measurement module is used to calculate the radar backscattering coefficient based on the dielectric constant, surface roughness, radar parameters and radar echo signal of the paper package; based on the backscattering coefficient, a mathematical model between the backscattering coefficient and the moisture content of the paper package is constructed by linear regression method, and the mathematical model is solved to realize the measurement and calculation of the moisture content of the paper package.

[0017] According to some embodiments, the present disclosure adopts the following technical solutions:

[0018] A computer program product comprises a computer program, wherein when the computer program is executed by a processor, the paper moisture content measurement method based on radar backscattering is implemented.

[0019] According to some embodiments, the present disclosure adopts the following technical solutions:

[0020] A non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the paper moisture content measurement method based on radar backscattering is implemented.

[0021] According to some embodiments, the present disclosure adopts the following technical solutions:

[0022] An electronic device comprises: a processor, a memory and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device implements the paper moisture content measurement method based on radar backscattering.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The paper moisture content measurement method based on radar backscattering disclosed in the present invention measures the paper moisture content based on radar technology, and can realize non-contact measurement of paper moisture content using radar technology. This method can not only overcome the limitations of traditional measurement methods, but also quickly and accurately evaluate the moisture status of paper in a large range, and has important application value in life and industrial fields.

[0025] The paper moisture content measurement method based on radar backscattering disclosed in the present invention is that when radar waves propagate in paper, their reflection intensity is affected by the dielectric constant, and the dielectric constant increases with the increase of moisture content. The moisture content of paper can be estimated by analyzing the backscattering coefficient, and a low-frequency radar in the 30MHz frequency band is selected for observation. The low frequency has a greater penetration depth and can capture more internal moisture information.

[0026] The paper moisture content measurement method based on radar backscattering disclosed in the present invention provides a paper moisture content measurement system based on radar technology, which can realize accurate measurement of different types of paper. Through signal processing and image display, the moisture content in the paper can be intuitively reflected, achieving efficient, accurate and non-destructive measurement requirements. The paper moisture content measurement method is simple, flexible, fast and easy to measure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure.

[0028] Figure 1 A schematic diagram of a radar system and a process for measuring the moisture content of paper according to an embodiment of the present disclosure; DETAILED DESCRIPTION

[0029] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present disclosure belongs.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] Example 1

[0033] In one embodiment of the present disclosure, a method for measuring moisture content of paper based on radar backscattering is provided, comprising:

[0034] Step 1: Obtain the target paper package to be tested and determine the dielectric constant of the target paper package;

[0035] Step 2: transmitting a radar signal to the target paper bag at a predetermined angle and frequency, and receiving a returned radar echo signal;

[0036] Step 3: Calculate the radar backscatter coefficient based on the dielectric constant, surface roughness, radar parameters and radar echo signal of the paper package;

[0037] Step 4: Based on the backscattering coefficient, a mathematical model between the backscattering coefficient and the water content of the paper is constructed by linear regression method, and the mathematical model is solved to realize the measurement and calculation of the water content of the paper.

[0038] As an embodiment, the specific implementation process of the paper moisture content measurement method based on radar backscattering disclosed in the present invention is as follows:

[0039] Step 1: Obtain the target paper package to be tested and determine the dielectric constant of the target paper package;

[0040] Specifically, first, the dielectric constant ε of the paper bag w It is closely related to the water content of the paper bag. The dielectric constant of the paper bag is expressed as:

[0041] ε r =ε w ·V w +ε d (1-V w )

[0042] Among them, ε r is the dielectric constant of water, ε w is the dielectric constant of the dry paper bag, V w is the volumetric water content, ε d is the dielectric constant of dry paper fiber.

[0043] Step 2: transmitting a radar signal to the target paper bag at a predetermined angle and frequency, and receiving a returned radar echo signal;

[0044] Specifically, the present disclosure provides a radar technology, and a radar system is set up to measure the moisture content of paper. The radar system includes a power board, a radar transmitting board, a receiving board (intermediate frequency sampling board), a radar array antenna and a signal extraction unit, wherein the radar transmission frequency is 30MHz, the wavelength is about 10 meters, the pulse width is: 50-100 microseconds, the antenna type is a vertical array antenna, the beam width is 5°, and the maximum detection distance is more than 100 meters.

[0045] The transmitter generates high-frequency electromagnetic waves and transmits them to the paper through the antenna. The antenna is not only responsible for the direction of the beam, but also ensures that the electromagnetic waves can fully cover the area to be tested. The moisture content of the paper will affect the reflection characteristics of the electromagnetic waves. The reflected signal is captured and amplified by the receiver and then transmitted to the signal processing unit. The signal processing unit extracts information reflecting the moisture content of the paper by filtering and analyzing the intensity and phase changes of the echo signal. Finally, the moisture content data is presented in the form of an image through the display system, which is convenient for observing and analyzing the moisture distribution of the paper.

[0046] Furthermore, in the process, the antenna array is optimized and a vertical antenna array board with adjustable height is provided, wherein the receiving antenna is composed of six antennas arranged vertically in the center of the antenna board, and the transmitting antenna is composed of one antenna on each side of the board.

[0047] The antenna board can manually adjust the antenna height and quantity according to the height and volume of the measured object to adapt to the best measurement conditions.

[0048] The antenna units of the vertical array are spaced a certain distance apart from each other, and these intervals are used to collect reflected signals at different heights. In this way, the vertical array can capture target information that changes with height, allowing the radar system to detect the moisture content characteristics of paper at different heights.

[0049] Furthermore, the frequency of the antenna transmitting the radar signal to the target paper package is optimized, and the spacing between independent frequency samples is calculated. Assuming that the target area is composed of randomly distributed discrete independent scatterers, the received signal envelope is a random variable, and its amplitude obeys the Rayleigh distribution. In this case, the spacing between independent frequency samples is calculated by the following formula:

[0050]

[0051] Where D is the distance between the farthest and closest points measured radially from the radar antenna.

[0052] For radar systems, the distance between the farthest and closest points measured radially from the radar antenna is determined by the geometric relationship:

[0053] D=R n -R 1 =H·sin(θ i )

[0054] Where H is the height of the antenna from the ground, R n is the horizontal distance between the farthest measurement point of the radar beam on the ground and the radar antenna, R 1 θ is the horizontal distance between the closest measurement point of the radar beam on the ground and the radar antenna. i is the observation angle.

[0055] Step 3: Calculate the radar backscatter coefficient based on the dielectric constant, surface roughness, radar parameters and radar echo signal of the paper package;

[0056] Specifically, the radar backscatter coefficient σ 0 It is one of the key parameters for measuring the amount of water in a paper package. It reflects the amount of energy returned by the radar wave after it irradiates the paper package, and is related to the dielectric constant of the paper, surface roughness, radar parameters, etc. The backscatter coefficient is expressed as:

[0057] σ 0 =|R| 2 ·F(θ i ,λ,h)

[0058] Where R is the reflection coefficient, F(θ i ,λ,h) is a function representing the observation angle θ i , wavelength λ and surface roughness h on scattering.

[0059] Step 4: Based on the backscattering coefficient, a mathematical model between the backscattering coefficient and the water content of the paper is constructed by a linear regression method, and the mathematical model is solved to achieve the measurement and calculation of the water content of the paper.

[0060] Specifically, based on the dielectric constant, surface roughness, radar parameters and radar echo signal of the paper package, the radar backscattering coefficient is calculated, and a mathematical model between the backscattering coefficient and the moisture content of the paper is established. The specific calculation process is as follows:

[0061]

[0062] Among them, P rx is the received power, P tx is the transmit power, G tx is the transmit antenna gain, G rx is the receiving antenna gain, λ is the radar wavelength, and r is the distance between the radar and the target.

[0063] The present invention discloses the analysis results. When radar waves propagate in paper, their reflection intensity is affected by the dielectric constant, and the dielectric constant increases with the increase of moisture content. The moisture content of paper can be estimated by analyzing the backscattering coefficient.

[0064] This paper uses a low-frequency radar in the 30MHz frequency band for observation. The low frequency has a greater penetration depth and can capture more internal moisture information. In the range of 15%-30% paper moisture content, the radar response shows a linear relationship. This means that within this range, a mathematical model between the backscatter coefficient and the paper moisture content can be established through a simple linear regression method, thereby achieving accurate measurement of the paper moisture content.

[0065] Example 2

[0066] In one embodiment of the present disclosure, a paper moisture content measurement system based on radar backscattering is provided, comprising:

[0067] A preprocessing module, used to obtain a target paper package to be tested and determine the dielectric constant of the target paper package;

[0068] A signal acquisition module, used to transmit a radar signal to the target paper bag at a predetermined angle and frequency point, and receive a returned radar echo signal;

[0069] The model building and measurement module is used to calculate the radar backscattering coefficient based on the dielectric constant, surface roughness, radar parameters and radar echo signal of the paper package; based on the backscattering coefficient, a mathematical model between the backscattering coefficient and the moisture content of the paper package is constructed by linear regression method, and the mathematical model is solved to realize the measurement and calculation of the moisture content of the paper package.

[0070] Example 3

[0071] In one embodiment of the present disclosure, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the paper moisture content measurement method based on radar backscattering is implemented.

[0072] Example 4

[0073] In one embodiment of the present disclosure, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the paper moisture content measurement method based on radar backscattering is implemented.

[0074] Example 5

[0075] In one embodiment of the present disclosure, an electronic device is provided, including: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device executes the paper moisture content measurement method based on radar backscattering.

[0076] The present disclosure is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present disclosure. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0077] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0078] Although the above describes the specific implementation methods of the present disclosure in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present disclosure. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present disclosure, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present disclosure.

Claims

1. A paper moisture content measurement method based on radar backscattering, characterized in that: include: Obtain a target paper package to be tested, and determine the dielectric constant of the target paper package; Transmitting a radar signal to the target paper bag at a predetermined angle and frequency, and receiving a returned radar echo signal; Calculate the radar backscatter coefficient based on the dielectric constant, surface roughness, radar parameters and radar echo signal of the paper package; Based on the backscattering coefficient, a mathematical model between the backscattering coefficient and the moisture content of the paper is constructed by the linear regression method, and the mathematical model is solved to realize the measurement and calculation of the moisture content of the paper.

2. The paper moisture content measurement method based on radar backscattering according to claim 1, characterized in that: The dielectric constant of the paper package is closely related to the amount of water in the paper package. The dielectric constant of the paper package is expressed as: e r =e w ·V w +e d ·(1-V w ) Among them, ε r is the dielectric constant of water, ε w is the dielectric constant of the dry paper bag, V w is the volumetric water content, ε d is the dielectric constant of dry paper fiber.

3. The paper moisture content measurement method based on radar backscattering according to claim 1, characterized in that: The radar backscatter coefficient is one of the key parameters for measuring the amount of water in a paper package. It is the amount of energy returned by the radar wave after it irradiates the paper package. It is related to the dielectric constant, surface roughness and radar parameters of the paper. The backscatter coefficient is expressed as: s 0 =|R| 2 ·F(θ i ,λ,h) Where R is the reflection coefficient, F(θ i ,λ,h) is a function representing the observation angle θ i , wavelength λ and surface roughness h on scattering.

4. The paper moisture content measurement method based on radar backscattering according to claim 1, characterized in that: Based on the dielectric constant, surface roughness, radar parameters and radar echo signal of the paper package, the radar backscattering coefficient is calculated. The specific calculation process is as follows: Among them, P rx is the received power, P tx is the transmit power, G tx is the transmit antenna gain, G rx is the receiving antenna gain, λ is the radar wavelength, and r is the distance between the radar and the target.

5. The paper moisture content measurement method based on radar backscattering according to claim 1, characterized in that: The frequency of transmitting the radar signal to the target paper bag is optimized, and the spacing between independent frequency samples is calculated. Assuming that the target area is composed of randomly distributed discrete independent scatterers, the received signal envelope is a random variable whose amplitude obeys the Rayleigh distribution. In this case, the spacing between independent frequency samples is calculated by the following formula: Where D is the distance between the farthest and closest points measured radially from the radar antenna.

6. The paper moisture content measurement method based on radar backscattering according to claim 5, characterized in that: For radar systems, the distance between the farthest and closest points measured radially from the radar antenna is determined by the geometric relationship: D=R n -R1=H·sin(θ i ) Where H is the height of the antenna from the ground, R n is the horizontal distance between the farthest measurement point of the radar beam on the ground and the radar antenna, R1 is the horizontal distance between the closest measurement point of the radar beam on the ground and the radar antenna, θ i is the observation angle.

7. The paper moisture content measurement system based on radar backscattering is characterized in that: include: A preprocessing module, used to obtain a target paper package to be tested and determine the dielectric constant of the target paper package; A signal acquisition module, used to transmit a radar signal to the target paper bag at a predetermined angle and frequency point, and receive a returned radar echo signal; The model building and measurement module is used to calculate the radar backscattering coefficient based on the dielectric constant, surface roughness, radar parameters and radar echo signal of the paper package; based on the backscattering coefficient, a mathematical model between the backscattering coefficient and the moisture content of the paper package is constructed by linear regression method, and the mathematical model is solved to realize the measurement and calculation of the moisture content of the paper package.

8. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the paper moisture content measurement method based on radar backscattering according to any one of claims 1 to 6 is implemented.

9. A non-transitory computer-readable storage medium, characterized in that: The non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by the processor, the paper moisture content measurement method based on radar backscattering as described in any one of claims 1 to 6 is implemented.

10. An electronic device, characterized in that: include: A processor, a memory and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory so that the electronic device executes the paper moisture content measurement method based on radar backscattering as described in any one of claims 1 to 6.

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