CN113030961A - Device and method for detecting plant trunk internal plant diseases and insect pests based on electromagnetic wave imaging - Google Patents

Device and method for detecting plant trunk internal plant diseases and insect pests based on electromagnetic wave imaging Download PDF

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CN113030961A
CN113030961A CN202110441785.6A CN202110441785A CN113030961A CN 113030961 A CN113030961 A CN 113030961A CN 202110441785 A CN202110441785 A CN 202110441785A CN 113030961 A CN113030961 A CN 113030961A
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electromagnetic wave
plant
radar
layer
plant trunk
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孙伟
刘继芳
曹姗姗
孔繁涛
吴建寨
王亚鹏
程国栋
王雍涵
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Agricultural Information Institute of CAAS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • G01S7/411—Identification of targets based on measurements of radar reflectivity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • G01S7/418—Theoretical aspects

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Abstract

The invention provides a plant trunk internal pest detection device based on electromagnetic wave imaging, which comprises a radar chip module and an electromagnetic wave transmitting and receiving device, wherein the electromagnetic wave transmitting and receiving device is used for transmitting and receiving electromagnetic waves, the radar chip module is in bidirectional connection with the electromagnetic wave transmitting and receiving device, the collected electromagnetic waves are converted into a digital form through the radar chip module and are stored, the electromagnetic wave transmitting and receiving device is in signal connection with a radar antenna, the radar antenna is attached to the periphery of a plant trunk to be detected and is used for measuring the plant trunk by the electromagnetic waves generated by the electromagnetic wave transmitting and receiving device, the radar chip module is also in signal connection with a display and an analysis module, the display is used for displaying measured data, the analysis module is used for analyzing trunk data and determining pest and disease information in the plant to be detected, the invention not only, and defective live fruit trees can be timely cured, so that the quality and the yield of the fruit trees are improved.

Description

Device and method for detecting plant trunk internal plant diseases and insect pests based on electromagnetic wave imaging
Technical Field
The invention belongs to the technical field of plant trunk pest detection, and particularly relates to a device and a method for detecting plant trunk internal pest based on electromagnetic wave imaging.
Background
In recent years, the use of scientific planting technology effectively improves agricultural products in China, and the increase of fruit tree yield accounts for a great proportion of agricultural yield. However, many farmers in China neglect the control of plant diseases and insect pests, so that the yield of fruit trees is reduced, and the economic loss is caused. In the growth process of fruit trees, diseases and insect pests can cause important influence on the fruit trees, and even can cause death or morbidity of the fruit trees. Many fruit growers are not aware of the disease and pest control, usually know the severity of the problem only when discovering the death, the pathological changes and the invasion of pests of fruit trees, and meanwhile, many fruit growers are aware of the disease and pest control, but the control measures are not perfect, only the surface diseases and pests can be seen, the threat to the interior of the trunk of the fruit tree plant is not paid attention to, and the number of the diseases and pests is continuously increased.
However, in early fruit tree pest and disease defect detection, researchers mainly adopt traditional detection methods such as a visual method, a knocking sound discrimination method and an anatomy observation method due to the lack of corresponding equipment and technology. Due to the limitation of the detection methods, the detection effect on the fruit tree pest and disease defects is not ideal. The traditional detection methods, such as a visual detection method, a knocking sound discrimination method and an anatomical observation method, have the defects of low accuracy, easiness in causing irreversible damage to trees, poor timeliness and the like to different degrees, cannot effectively detect the fruit tree pest and disease damage defects, and are low in efficiency, more in influenced factors and not suitable for detection of large-area fruit tree pests and diseases.
Disclosure of Invention
The present invention provides a device and a method for detecting plant diseases and insect pests in a plant trunk based on electromagnetic wave imaging, so as to solve the above problems in the background art.
In order to solve the technical problems, the invention adopts the technical scheme that: the plant trunk internal pest detection device based on electromagnetic wave imaging comprises a radar chip module and an electromagnetic wave transmitting and receiving device, wherein the electromagnetic wave transmitting and receiving device is used for transmitting and receiving electromagnetic waves, the radar chip module is in bidirectional connection with the electromagnetic wave transmitting and receiving device, and the collected electromagnetic waves are converted into a digital form and stored through the radar chip module;
the electromagnetic wave transmitting and receiving device is connected with a radar antenna in a signal mode, the radar antenna is attached to the periphery of the plant trunk to be measured and used for enabling the electromagnetic wave transmitting and receiving device to generate electromagnetic waves to measure the plant trunk;
the radar chip module is further connected with a display and an analysis module through signals, the display is used for displaying measured data, and the analysis module is used for analyzing data and determining information of plant diseases and insect pests in the plant trunk to be detected.
Preferably, the radar chip module is arranged at the geometric center of the packaging box, and the electromagnetic wave transceiver and the display are both arranged at the outer side of the packaging box.
The detection method of the plant trunk internal pest detection device based on electromagnetic wave imaging comprises the following steps:
s1, attaching the radar antenna to the periphery of the plant trunk to be measured to move, and generating a pulse signal for measuring the plant trunk to be measured by using the electromagnetic wave transmitting and receiving device;
s2, transmitting a pulse signal generated by the electromagnetic wave transmitter-receiver and used for measuring the plant trunk to be measured through a medium of the plant trunk to be measured, receiving the pulse signal through the electromagnetic wave transmitter-receiver, and transmitting the collected electromagnetic wave to the radar chip module;
s3, converting the collected electromagnetic waves into a digital form by the radar chip module, transmitting the digital form to the analysis module for analysis, and storing information;
and S4, analyzing the acquired electromagnetic waves by an analysis algorithm preset in the analysis module to determine the information of plant diseases and insect pests in the plant trunk to be detected.
Preferably, the information of the internal plant diseases and insect pests of the plant trunk to be detected comprises defect position information, electromagnetic tomography information and layer position analysis information of the plant trunk to be detected.
Preferably, the position information of the plant trunk defect to be detected is determined by determining the propagation speed of the electromagnetic wave and the dielectric constant through a maxwell equation system, and the method comprises the following steps:
s1, determining the defect position, wherein the defect position is detected by using high-frequency electromagnetic waves, the propagation of the high-frequency electromagnetic waves in the medium follows Maxwell equation set, and the differential form of the Maxwell equation set can be expressed as:
Figure BDA0003035357950000031
Figure BDA0003035357950000032
Figure BDA0003035357950000033
Figure BDA0003035357950000034
wherein ρ is the charge density; d is a potential shift; e is the electric field strength; b is magnetic induction; h is the magnetic field intensity; j is the current density; the four vectors D, E, B and h are called field quantities, and J and ρ are vector and scalar quantities;
assuming the medium is homogeneous, it is simplified to:
J＝σE
B＝μh
D＝εE
where σ is the electrical conductivity, μ is the magnetic permeability, and ε is the dielectric constant.
By integrating the two equations, a maxwell equation system only containing two vector field forms can be obtained:
Figure BDA0003035357950000035
Figure BDA0003035357950000036
Figure BDA0003035357950000037
Figure BDA0003035357950000038
standard wave equation in wave equation and mathematical physics equation obtained by deformation
Figure BDA0003035357950000039
And comparing to obtain the propagation speed of the electromagnetic wave:
Figure BDA00030353579500000310
s2, calculating according to the reflection time and the propagation speed of the radar waves in the healthy tree medium and the interface of the defect medium to obtain the position of the defect as follows:
Figure BDA0003035357950000041
h is the propagation speed from the bark to the healthy wood medium and the propagation speed from the bark to the defective wood medium, t is the echo time of electromagnetic waves in different medium structures, c is the light speed in vacuum, and epsilon is the dielectric constant;
s3, an amplitude method is used, namely the dielectric constant is solved by using the amplitude ratio of the radar echo signals to the medium reflected signals of each layer, and the received radar echo signals are approximately regarded as superposition of the interface reflected waves of each layer; suppose A1Amplitude of reflected wave at interface of air layer and 1 st dielectric layer, A2Amplitude of the reflected wave at the interface of the 1 st and 2 nd dielectric layers, AmFor the echo amplitude of the radar wave, the dielectric constant estimation formulas of the 1 st dielectric layer and the 2 nd dielectric layer are respectively:
Figure BDA0003035357950000042
Figure BDA0003035357950000043
and S4, substituting the dielectric constant obtained in the S3 into S2 to obtain the defect position information of the plant trunk to be detected.
Preferably, the determination of the electromagnetic tomography information is completed through an echo signal model established by a radar echo signal, and the echo signal model is;
Figure BDA0003035357950000044
wherein K is the number of dielectric layers, yr(t) represents an acceptance signal consisting of a reflection signal of the K-layer interface, AkThe amplitude of the reflected wave of the kth layer, x (t) the incident pulse, τ k the time delay of the kth echo, and n (t) the noise.
The resolution detection in the electromagnetic wave tomography method comprises the following steps:
the resolution ratio is the ability of distinguishing the echo amplitude of a quite static layer of a plant trunk layer, is related to the wavelength of a transmitted wave, the smaller the wavelength is, the higher the waveform model identification ability is, and otherwise, the lower the identification ability is, and the resolution ratio comprises longitudinal resolution ratio and transverse resolution ratio. According to the radar system theory, the range resolution of the radar is:
Figure BDA0003035357950000051
for the detection of the internal defects of the plant trunk, because the interior of the living standing tree is similar to a layered structure, the longitudinal resolution needs to pay attention, the longitudinal resolution is the capability of a single echo signal to distinguish two adjacent signals in a vertical direction time domain, and two pulses of the echo signal may be far away and completely separated in the time domain, or the waveforms of the two adjacent signals are overlapped at a close distance, or almost approximately overlapped.
According to the electromagnetic theory, the wavelength λ of an electromagnetic wave propagating in a medium is:
Figure BDA0003035357950000052
from the above formula, the maximum distance is inversely proportional to the center frequency, the dielectric constant and the magnetic permeability, when the thickness of the dielectric layer is equal to 1/2 of the wavelength, the reflection of the layer with equal section can generate destructive interference, and the interference is strengthened until the reflection disappears completely as the thickness of the layer becomes thinner; when the layer thickness reaches 1/8 wavelength, the reflected signal can not be received, and only the composite superposed signal can be received, which is the limit of longitudinal resolution.
Preferably, the horizon analysis method estimates the layer thickness by using a hilbert product algorithm, and performs EMD decomposition on the echo signal to obtain N IMF components c1(t)～cn(t), and then calculating the dot product of all IMF negative energy absolute values as:
Figure BDA0003035357950000053
since the echo signal contains a positive peak and a negative peak, so that the received signal is composed of multi-peak pulses, which is prone to false detection, the signal needs to be smoothed by a window function. Performing convolution by using P (t) and a window function W (t) to complete the smoothing process:
T(t)＝W(t)*P(t)
judging the sizes of T (t) and a threshold value V (t), judging that the reflecting layer is detected when the signal of T (t) is greater than the threshold value, and calculating corresponding time delay; otherwise no reflective layer is detected.
Compared with the prior art, the invention has the following advantages:
1. the method is a wood nondestructive detection technology, can grasp the performance of the fruit tree wood and can timely cure the defective live fruit trees by using nondestructive detection, thereby improving the quality and the yield of the fruit trees.
2. The electromagnetic wave detection technology and the imaging algorithm have the characteristics of quickness and simplicity in operation, high imaging precision and the like, can quantitatively evaluate the positions, sizes and shapes of the diseases and insect hole defects in the trees, and play a positive role in accurately detecting the diseases and insect pests in the trees.
3. The accurate detection device for the internal pest and disease damage defects of the trunks of the fruit trees and plants based on electromagnetic wave imaging has the advantages of portability, strong flexibility, simplicity in operation, safe detection process, no damage to wood, no pollution to the surrounding environment and no radiation damage to human bodies, and is a nondestructive detection device in the true sense.
4. The invention can estimate the layer thickness through tests and analyze the internal condition of the plant trunk. Common detection methods are threshold detection, matched-Asahi filter, Hilbert-product algorithm, etc. Threshold detection is the simplest horizon analysis method, but when the signal-to-noise ratio of an echo signal is small, the relative error of threshold detection is large; the matched filter cannot effectively detect the overlapped echo signals, and the accuracy is poor. The invention adopts the Hilbert product algorithm to detect and identify different positions in the plant trunk, and can effectively estimate the layer thickness.
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FIG. 1 is a schematic block diagram of the present invention;
description of reference numerals:
1-a radar chip module; 2-an electromagnetic wave transmitter-receiver; 3-a display; 4-a radar antenna; 5-an analysis module.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Embodiment 1, as shown in fig. 1, the present invention provides a technical solution: inside plant diseases and insect pests detection device of trunk based on electromagnetic wave formation of image, including radar chip module 1 and electromagnetic wave transceiver 2, electromagnetic wave transceiver 2 is used for launching and receiving the electromagnetic wave, two-way connection between radar chip module 1 and the electromagnetic wave transceiver 2 converts the electromagnetic wave of gathering into digital form through radar chip module 1 to the storage.
The radar chip module 1 is arranged at the geometric center of the packaging box 6, and the electromagnetic wave transceiver 2 and the display 3 are both arranged at the outer side of the packaging box 6.
The electromagnetic wave transmitting and receiving device 2 is connected with a radar antenna 4 in a signal mode, and the radar antenna 4 is attached to the periphery of a plant trunk to be measured and used for measuring the plant trunk by electromagnetic waves generated by the electromagnetic wave transmitting and receiving device 2;
radar chip module 1 still signal connection has display 3 and analysis module 5, display 3 is used for accomplishing measured data's demonstration, analysis module 5 is used for data analysis and confirms the information of the plant trunk inside plant diseases and insect pests that awaits measuring.
Embodiment 2, the detection method of the device for detecting plant internal diseases and insect pests based on electromagnetic wave imaging in embodiment 1 includes the following steps:
s1, attaching the radar antenna 4 to the periphery of the plant trunk to be measured to move, and generating a pulse signal for measuring the plant trunk to be measured by using the electromagnetic wave transceiver 2;
s2, transmitting a pulse signal generated by the electromagnetic wave transceiver 2 and used for measuring the plant trunk to be measured through a medium of the plant trunk to be measured, receiving the pulse signal through the electromagnetic wave transceiver 2, and transmitting the collected electromagnetic wave to the radar chip module 1;
s3, the radar chip module 1 converts the collected electromagnetic waves into a digital form, transmits the digital form to the analysis module 5 for analysis, and stores the information;
s4, the analysis module 5 analyzes the collected electromagnetic waves through an analysis algorithm preset in the analysis module, and determines the information of plant diseases and insect pests in the plant trunk to be detected.
The information of the plant diseases and insect pests in the plant trunk to be detected comprises defect position information, electromagnetic wave tomography information and layer position analysis information of the plant trunk to be detected.
The plant trunk defect position information to be detected is determined by determining the electromagnetic wave propagation speed and the dielectric constant through a Maxwell equation system, and the method comprises the following steps:
s1, determining the defect position, wherein the defect position is detected by using high-frequency electromagnetic waves, the propagation of the high-frequency electromagnetic waves in the medium follows Maxwell equation set, and the differential form of the Maxwell equation set can be expressed as:
Figure BDA0003035357950000081
Figure BDA0003035357950000082
Figure BDA0003035357950000083
Figure BDA0003035357950000084
wherein ρ is the charge density; d is a potential shift; e is the electric field strength; b is magnetic induction; h is the magnetic field intensity; j is the current density; the four vectors D, E, B and h are called field quantities, and J and ρ are vector and scalar quantities;
assuming the medium is homogeneous, it is simplified to:
J＝σE
B＝μh
D＝εE
where σ is the electrical conductivity, μ is the magnetic permeability, and ε is the dielectric constant.
By integrating the two equations, a maxwell equation system only containing two vector field forms can be obtained:
Figure BDA0003035357950000085
Figure BDA0003035357950000086
Figure BDA0003035357950000087
Figure BDA0003035357950000088
standard wave equation in wave equation and mathematical physics equation obtained by deformation
Figure BDA0003035357950000089
And comparing to obtain the propagation speed of the electromagnetic wave:
Figure BDA00030353579500000810
s2, calculating according to the reflection time and the propagation speed of the radar waves in the healthy tree medium and the interface of the defect medium to obtain the position of the defect as follows:
Figure BDA0003035357950000091
h is the propagation speed from the bark to the healthy wood medium and the propagation speed from the bark to the defective wood medium, t is the echo time of electromagnetic waves in different medium structures, c is the light speed in vacuum, and epsilon is the dielectric constant;
s3, an amplitude method is used, namely the dielectric constant is solved by using the amplitude ratio of the radar echo signals to the medium reflected signals of each layer, and the received radar echo signals are approximately regarded as superposition of the interface reflected waves of each layer; suppose A1Amplitude of reflected wave at interface of air layer and 1 st dielectric layer, A2Amplitude of the reflected wave at the interface of the 1 st and 2 nd dielectric layers, AmFor the echo amplitude of the radar wave, the dielectric constant estimation formulas of the 1 st dielectric layer and the 2 nd dielectric layer are respectively:
Figure BDA0003035357950000092
Figure BDA0003035357950000093
and S4, substituting the dielectric constant obtained in the S3 into S2 to obtain the defect position information of the plant trunk to be detected.
The electromagnetic wave tomography information is determined through an echo signal model established by radar echo signals, and different medium layer positions and abnormal areas in the plant trunk can be identified through the frequency spectrum characteristics of the echo signals. The echo signal model is;
Figure BDA0003035357950000094
wherein K is a mediumNumber of layers, yr(t) represents an acceptance signal consisting of a reflection signal of the K-layer interface, AkThe amplitude of the reflected wave of the kth layer, x (t) the incident pulse, τ k the time delay of the kth echo, and n (t) the noise.
The resolution detection in the electromagnetic wave tomography method comprises the following steps:
the resolution ratio is the ability of distinguishing the echo amplitude of a quite static layer of a plant trunk layer, is related to the wavelength of a transmitted wave, the smaller the wavelength is, the higher the waveform model identification ability is, and otherwise, the lower the identification ability is, and the resolution ratio comprises longitudinal resolution ratio and transverse resolution ratio. According to the radar system theory, the range resolution of the radar is:
Figure BDA0003035357950000101
for the detection of the internal defects of the plant trunk, because the interior of the living standing tree is similar to a layered structure, the longitudinal resolution needs to pay attention, the longitudinal resolution is the capability of a single echo signal to distinguish two adjacent signals in a vertical direction time domain, and two pulses of the echo signal may be far away and completely separated in the time domain, or the waveforms of the two adjacent signals are overlapped at a close distance, or almost approximately overlapped.
According to the electromagnetic theory, the wavelength λ of an electromagnetic wave propagating in a medium is:
Figure BDA0003035357950000102
from the above formula, the maximum distance is inversely proportional to the center frequency, the dielectric constant and the magnetic permeability, when the thickness of the dielectric layer is equal to 1/2 of the wavelength, the reflection of the layer with equal section can generate destructive interference, and the interference is strengthened until the reflection disappears completely as the thickness of the layer becomes thinner; when the layer thickness reaches 1/8 wavelength, the reflected signal can not be received, and only the composite superposed signal can be received, which is the limit of longitudinal resolution.
The horizon analysis method estimates the layer thickness by using a Hilbert product algorithm and carries out echo signal estimation firstPerforming EMD to obtain N IMF components c1(t)～cn(t), and then calculating the dot product of all IMF negative energy absolute values as:
Figure BDA0003035357950000103
since the echo signal contains a positive peak and a negative peak, so that the received signal is composed of multi-peak pulses, which is prone to false detection, the signal needs to be smoothed by a window function. Performing convolution by using P (t) and a window function W (t) to complete the smoothing process:
T(t)＝W(t)*P(t)
judging the sizes of T (t) and a threshold value V (t), judging that the reflecting layer is detected when the signal of T (t) is greater than the threshold value, and calculating corresponding time delay; otherwise, no reflecting layer is detected, and different media are positioned and layered through a Hilbert-product algorithm.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (7)

1. The plant trunk internal pest detection device based on electromagnetic wave imaging is characterized by comprising a radar chip module (1) and an electromagnetic wave transceiver (2), wherein the electromagnetic wave transceiver (2) is used for transmitting and receiving electromagnetic waves, the radar chip module (1) and the electromagnetic wave transceiver (2) are connected in a bidirectional mode, and collected electromagnetic waves are converted into a digital form through the radar chip module (1) and are stored;
the electromagnetic wave transmitting and receiving device (2) is connected with a radar antenna (4) in a signal mode, and the radar antenna (4) is attached to the periphery of the plant trunk to be measured and used for measuring the plant trunk by the electromagnetic waves generated by the electromagnetic wave transmitting and receiving device (2);
radar chip module (1) still signal connection has display (3) and analysis module (5), display (3) are used for accomplishing measured data's demonstration, analysis module (5) are used for data analysis and confirm the information of the plant trunk inside plant diseases and insect pests that awaits measuring.
2. The plant trunk internal pest detection device based on electromagnetic wave imaging according to claim 1, wherein the radar chip module (1) is arranged at the geometric center of the packaging box (6), and the electromagnetic wave transceiver (2) and the display (3) are both arranged at the outer side of the packaging box (6).
3. The detection method of the plant trunk internal pest detection device based on electromagnetic wave imaging is characterized by comprising the following steps:
s1, attaching the radar antenna (4) to the periphery of the plant trunk to be measured to move, and generating a pulse signal for measuring the plant trunk to be measured by using the electromagnetic wave transmitting and receiving device (2);
s2, transmitting a pulse signal generated by the electromagnetic wave transmitter-receiver (2) and used for measuring the plant trunk to be measured through a medium of the plant trunk to be measured, receiving the pulse signal through the electromagnetic wave transmitter-receiver (2), and transmitting the collected electromagnetic wave to the radar chip module (1);
s3, converting the collected electromagnetic waves into a digital form by the radar chip module (1), transmitting the digital form to the analysis module (5) for analysis, and storing information;
s4, the analysis module (5) analyzes the collected electromagnetic waves through an analysis algorithm preset in the analysis module to determine the information of plant diseases and insect pests in the plant trunk to be detected.
4. The method for detecting the internal plant pest detection device based on electromagnetic wave imaging according to claim 3, wherein the information of the internal plant pest of the plant trunk to be detected comprises position information of a defect of the plant trunk to be detected, electromagnetic wave tomography information and horizon analysis information.
5. The detection method of the electromagnetic wave imaging-based plant stem internal pest detection device, according to claim 4, wherein the plant stem defect position information to be detected is determined by determining the electromagnetic wave propagation speed and the dielectric constant through Maxwell equation system, and the method comprises the following steps:
s1, determining the defect position, wherein the defect position is detected by using high-frequency electromagnetic waves, the propagation of the high-frequency electromagnetic waves in the medium follows Maxwell equation set, and the differential form of the Maxwell equation set can be expressed as:
Figure FDA0003035357940000027
Figure FDA0003035357940000021
Figure FDA0003035357940000028
Figure FDA0003035357940000022
wherein ρ is the charge density; d is a potential shift; e is the electric field strength; b is magnetic induction; h is the magnetic field intensity; j is the current density; the four vectors D, E, B and h are called field quantities, and J and ρ are vector and scalar quantities;
assuming the medium is homogeneous, it is simplified to:
J＝σE
B＝μh
D＝εE
where σ is the electrical conductivity, μ is the magnetic permeability, and ε is the dielectric constant.
By integrating the two equations, a maxwell equation system only containing two vector field forms can be obtained:
Figure FDA0003035357940000023
Figure FDA0003035357940000024
Figure FDA0003035357940000025
Figure FDA0003035357940000026
standard wave equation in wave equation and mathematical physics equation obtained by deformation
Figure FDA0003035357940000031
And comparing to obtain the propagation speed of the electromagnetic wave:
Figure FDA0003035357940000032
s2, calculating according to the reflection time and the propagation speed of the radar waves in the healthy tree medium and the interface of the defect medium to obtain the position of the defect as follows:
Figure FDA0003035357940000033
h is the propagation speed from the bark to the healthy wood medium and the propagation speed from the bark to the defective wood medium, t is the echo time of electromagnetic waves in different medium structures, c is the light speed in vacuum, and epsilon is the dielectric constant;
s3, an amplitude method is used, namely the dielectric constant is solved by using the amplitude ratio of the radar echo signals to the medium reflected signals of each layer, and the received radar echo signals are approximately regarded as superposition of the interface reflected waves of each layer; suppose A1Amplitude of reflected wave at interface of air layer and 1 st dielectric layer, A2Amplitude of the reflected wave at the interface of the 1 st and 2 nd dielectric layers, AmFor the echo amplitude of the radar wave, the dielectric constant estimation formulas of the 1 st dielectric layer and the 2 nd dielectric layer are respectively:
Figure FDA0003035357940000034
Figure FDA0003035357940000035
and S4, substituting the dielectric constant obtained in the S3 into S2 to obtain the defect position information of the plant trunk to be detected.
6. The electromagnetic wave imaging-based plant trunk internal pest detection device and the electromagnetic wave imaging-based plant trunk internal pest detection method according to claim 4, wherein the electromagnetic wave tomography information is determined through an echo signal model established by radar echo signals, and the echo signal model is;
Figure FDA0003035357940000036
wherein K is the number of dielectric layers, yr(t) represents an acceptance signal consisting of a reflection signal of the K-layer interface, AkThe amplitude of the reflected wave of the kth layer, x (t) the incident pulse, τ k the time delay of the kth echo, and n (t) the noise.
The resolution detection in the electromagnetic wave tomography method comprises the following steps:
the resolution ratio is the ability of distinguishing the echo amplitude of a quite static layer of a plant trunk layer, is related to the wavelength of a transmitted wave, the smaller the wavelength is, the higher the waveform model identification ability is, and otherwise, the lower the identification ability is, and the resolution ratio comprises longitudinal resolution ratio and transverse resolution ratio. According to the radar system theory, the range resolution of the radar is:
Figure FDA0003035357940000041
for the detection of the internal defects of the plant trunk, because the interior of the living standing tree is similar to a layered structure, the longitudinal resolution needs to pay attention, the longitudinal resolution is the capability of a single echo signal to distinguish two adjacent signals in a vertical direction time domain, and two pulses of the echo signal may be far away and completely separated in the time domain, or the waveforms of the two adjacent signals are overlapped at a close distance, or almost approximately overlapped.
According to the electromagnetic theory, the wavelength λ of an electromagnetic wave propagating in a medium is:
Figure FDA0003035357940000042
from the above formula, the maximum distance is inversely proportional to the center frequency, the dielectric constant and the magnetic permeability, when the thickness of the dielectric layer is equal to 1/2 of the wavelength, the reflection of the layer with equal section can generate destructive interference, and the interference is strengthened until the reflection disappears completely as the thickness of the layer becomes thinner; when the layer thickness reaches 1/8 wavelength, the reflected signal can not be received, and only the composite superposed signal can be received, which is the limit of longitudinal resolution.
7. The device and the method for detecting plant trunk internal plant diseases and insect pests based on electromagnetic wave imaging as claimed in claim 4, wherein the horizon analysis method estimates the layer thickness through a Hilbert-product algorithm and performs EMD on the echo signal to obtain N IMF components c1(t)～cn(t), and then calculating the dot product of all IMF negative energy absolute values as:
Figure FDA0003035357940000043
since the echo signal contains a positive peak and a negative peak, so that the received signal is composed of multi-peak pulses, which is prone to false detection, the signal needs to be smoothed by a window function. Performing convolution by using P (t) and a window function W (t) to complete the smoothing process:
T(t)＝W(t)*P(t)
judging the sizes of T (t) and a threshold value V (t), judging that the reflecting layer is detected when the signal of T (t) is greater than the threshold value, and calculating corresponding time delay; otherwise no reflective layer is detected.
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CN117473272A (en) * 2023-12-26 2024-01-30 齐鲁工业大学(山东省科学院) Object position identification method, system, equipment and medium based on magnetic field data

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117473272A (en) * 2023-12-26 2024-01-30 齐鲁工业大学(山东省科学院) Object position identification method, system, equipment and medium based on magnetic field data
CN117473272B (en) * 2023-12-26 2024-03-15 齐鲁工业大学(山东省科学院) Object position identification method, system, equipment and medium based on magnetic field data

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