CN1991344A - Electromagnetic wave resonance cavity method for accurate diagnosis of plant moisture - Google Patents

Abstract

The invention relates to a lossless detection method for the water of activity plant using the electromagnetic wave technique. It includes following steps: 1, the strong interaction region of the electromagnetic wave and the object to be measured is provided; 2, the computer reads the output voltage in the resonance region without the resonance frequency and the electromagnetic wave signal of the object to be measured, calculate the resonance frequency and Q value, list and store in the computer, and finish the preparation course of test; 3, the computer reads the output voltage in the resonance region with the resonance frequency and the electromagnetic wave signal of the object to be measured, calculate the resonance frequency and Q value, list and store in the computer, and finish the preparation course of test; 4, the change of water content can be inversed according to the output voltage of the resonance frequency and the electromagnetic wave signal in step 3 and step 4. The invention could detect the change of water content of the root, caudex and leaf to monitor the change of water content, and it has high measurement accuracy, wide measured range and not effect by the measuring force.

Description

A kind of electromagnetic wave resonance cavity method of accurate diagnosis of plant moisture

Technical field

The present invention relates to a kind of method with electromagnetic wave technology Non-Destructive Testing active plant moisture.

Background technology

Shortage of water resources is the principal element of restriction development of world economy and ecological reconstruction, and focus, particularly using water wisely that development of water resources and using water wisely have become people's research have a high potential.For example, the utilization factor of developed country's agricultural irrigation water can reach more than 80%, and China only is 30%～40%.Therefore water-saving irrigation is the only way that solves China's water shortage problem.For plant moisture monitoring, diagnosing Study on Technology, can be divided into following three phases.

Phase one, judge whether lack of water of plant according to soil moisture.Tradition soil moisture measurement technology has capacitance method and electric-resistivity method.Recently, people such as Huebner has introduced the application of TDR method on measured soil moisture; Sachs has introduced the application of UWB technology on measured soil moisture; People such as Balendonck have introduced the application of MCM120 on measured soil moisture.In general, adopt the frequency electromagnetic waves measuring accuracy higher, be subjected to the influence of factors such as salt accumulation little.

Subordinate phase adopts sprinkler irrigation technique, and the water-saving irrigation technique of robotization occurred.Main detection index is temperature, soil moisture and ambient humidity, and it increases substantially water-saving rate.

Phase III, study the sensor technology that the fast detecting plant moisture wanes, set up impression, transmission and the conductive process of plant moisture information, obtain plant moisture information diagnosis index system, the novel sensor technology and the product of exploitation diagnosis of plant water shortage status; Research plant moisture areal distribution detection technique and plant transpiration process Fast Detection Technique obtain soil moisture dynamic fast measuring and forecasting technique and product; Research plant growth information and moisture kinetic measurement information, the utilization modern information technologies are set up the plant precision irrigation system with monitoring, transmission, diagnosis and decision making function.

Modern age, plant water physiology studies show that, the variation of plant moisture state can reflect by the subtle change that takes place on each organ volumes such as its root, stem, leaf.For example, the scientist of Hebrew Univ Jerusalem Israel uses micron order vane thickness sensor the irrigation system of tomato is tested, and has obtained water-saving rate 35%, the effect of volume increase 40%.People such as Su Chen use LVDT-5 type displacement transducer corn, citrus etc. are measured, and have obtained 15.6% and 21.4% water-saving result respectively.But also there are a lot of problems in the micro-displacement sensor that can reach this magnitude at present.All there is contradiction as aspects such as measuring accuracy and measurement range, ergometry, measurement environment, physical dimension and weight.People such as Li Dongsheng have succeeded in developing the indirect flexible measuring sensor of plant leaf blade moisture.The result shows this sensor in the scope of 0～1mm, and sensor has the good linearity, and measurement range reaches designing requirement.Utilize this sensor that the blade measurement of a kind of pot flowers plant is shown, the morning, the thickness of blade raise gradually, and reduce mild then noon gradually, and the vane thickness variation has reflected the plant moisture variation.People such as Jiang Yunfei study and become specific inductive capacity type sensor, this sensor clip on blade, when leaf water changes, its variation in thickness, specific inductive capacity also changes, thereby obtains blade lack of water information.

Same inventor's application number is that the Chinese patent of 200410040027.X discloses " a kind of material composition and content detecting method ", is to relate to the application of a kind of electromagnetic wave spectrum technology on recognition material composition and content.The core of this method is a relaxation behavior of having considered material, the composition and the content of energy recognition material.But this method complexity need heat up to sample, is not suitable for diagnosing the moisture of active plant.

Summary of the invention

The objective of the invention is to overcome the shortcoming of prior art, monitor its moisture state by the moisture content change of direct measurement plant roots, stem, leaf and change, promptly use the method for electromagnetic wave resonance cavity accurate diagnosis of plant moisture.

By Theory of Electromagnetic Field as can be known, filled the cylindrical E of material for centre shown in Figure 1 ₀₁₀Field equation in the mould metal resonant cavity, medium is:

E _z(r)＝E _maxJ ₀(r)

Outside the medium, the field equation in the wire chamber is:

E _z(r)＝A ₂J ₀(k ₂r)+B ₂Y ₁(k ₂r)

In the following formula, J first kind Bessel function; Y is the second class Bessel function; J ₀It is zeroth order first kind Bessel function; Y ₁It is the zeroth order second class Bessel function; ε _a, ε _bWith μ _a, μ _bBe respectively the specific inductive capacity and the magnetic permeability in a district and b district; ${\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="A20051004878600121.png"\; state="\{\{state\}\}">k</figure-callout>}}_1=\mathrm{\&omega;}/c\sqrt{{\mathrm{\&epsiv;}}_a{\mathrm{\&mu;}}_a},$ ${\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="A20051004878600121.png"\; state="\{\{state\}\}">k</figure-callout>}}_2=\mathrm{\&omega;}/c\sqrt{{\mathrm{\&epsiv;}}_b{\mathrm{\&mu;}}_b}.$ Utilize field boundary condition to get:

f ₁(P _rk ₀)＝f ₂(k ₀，k ₀b/a)

In the following formula, f ₁And f ₂Be respectively the first kind and the second class Bessel function; ${\mathrm{<figure-callout\; id="2"\; label="p\; r"\; filenames="A20051004878600121.png"\; state="\{\{state\}\}">p</figure-callout>}}_r^{}={\mathrm{\&epsiv;}}_a/{\mathrm{\&epsiv;}}_b;$ ${\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="A20051004878600101.png"\; state="\{\{state\}\}">k</figure-callout>}}_0=\mathrm{\&omega;}\sqrt{{\mathrm{\&epsiv;}}_b}b/c.$

Find the solution the relation that above-mentioned transcendental equation is promptly known resonant frequency and the medium radius and the medium specific inductive capacity of resonant cavity.At medium radius one regularly, also just obtain the relation of the resonant frequency and the medium specific inductive capacity of resonant cavity.

If with frequency sweep excitation of electromagnetic wave resonant cavity shown in Figure 1, the experimental provision block scheme is seen Fig. 2.By the electromagnetic wave Circuit theory as can be known, the resonance curve of resonant cavity can come match with following equation:

$|S_{21}{|}^2=\frac{x}{y+{(z-f)}^2}$

In the following formula, x, y, z are fitting parameters; f _r=z is the resonant frequency of resonant cavity; $Q=z/2\sqrt{y}$ Be total to the quality factor (Q value) in chamber.Because:

This shows, in incident power one regularly,, can measure the resonance frequency and the Q value of resonant cavity by the power that detects transmission ripple in the resonant cavity the frequency sweep electromagnetic wave of different frequency.

If the plant that will put into resonant cavity is modeled as the potpourri of dried plant and water, its effective dielectric constant is:

ε _e＝ε ₁α ₁+ε ₂α ₂

In the following formula, ε ₁And ε ₂Be respectively the relative dielectric constant of water and dried plant; α ₁And α ₂Be respectively the volume ratio of water and dried plant.By above-mentioned discussion as seen, only need measure resonant cavity and surround before and after the plant resonant frequency of resonant cavity and the output voltage of electromagnetic wave signal.Calibrate by experiment, can be finally inversed by the moisture of plant.Fig. 3 and Fig. 4 are respectively the relations of resonant frequency and the Q value and the substance moisture content content of resonant cavity.

Experimental result is as follows:

Under the environment of experiment condition shown in Figure 2 and 25 ℃, utilize the electromagnetic spectrum of Yunnan shrub seedling, cuckoo flower seedling and evergreen sapling lack of water situation that the electromagnetic spectrum instrument of Jinhuitong Wire-less and Microwave Technology Inst., Kunming's exploitation measures to see Fig. 5～shown in Figure 7.Wherein, Fig. 5 has shown the electromagnetic spectrum figure of Yunnan shrub seedling lack of water situation; Fig. 6 has shown the electromagnetic spectrum figure of Yunnan cuckoo flower seedling lack of water situation; Fig. 7 has shown the electromagnetic spectrum figure of Yunnan evergreen sapling lack of water situation.Fig. 8～Fig. 9 has shown that the Yunnan shrub seedling waters the back every 10 days measurement situation, and the variation tendency of the variation tendency of the time that obtains after the data processing and the output voltage of electromagnetic wave signal and the resonant frequency of time and electromagnetic wave resonance cavity is seen Fig. 8 and shown in Figure 9 respectively.By above graph of a relation as can be seen, the output voltage of electromagnetic wave signal and the resonant frequency of electromagnetic wave resonance cavity change along with the variation of plant hydropenia state, and therefore, electromagnetic wave resonance cavity method can be used for the accurate diagnosis of plant water shortage status.

The electromagnetic wave resonance cavity method of accurate diagnosis of plant moisture of the present invention is made up of following steps:

One, the strong interaction resonance region of electromagnetic wave and determinand is provided;

Two, read the resonant frequency that do not have determinand in the resonance region and the output voltage of electromagnetic wave signal by computing machine, and calculate its resonant frequency and Q value, tabulation deposits computing machine in, finishes the experiment set-up procedure;

Three, read the resonant frequency that determinand is arranged in the resonance region and the output voltage of electromagnetic wave signal by computing machine, and calculate its resonant frequency and Q value, tabulation deposits computing machine in;

Four, according to the output voltage of step 2 and three resonant frequency and electromagnetic wave signal can its moisture of inverting variation.

Described determinand is respectively root, stem, the leaf of plant; The resonance region that described resonance region is produced by the resonant cavity of excitation of electromagnetic wave adopts the distribution parameter resonator cavity can make accuracy of detection higher.Described metal resonant cavity is open, and its shape can be multiple shape, as: annular, planar shaped, curved etc.When being shaped as annular, determinand places among the annular; When being shaped as planar shaped, curved, planar shaped, curved should be near determinands, and its distance should be less than an electromagnetic wavelength of the resonant cavity that encourages.The temperature stability of resonance region will be got well, and when variation of ambient temperature, the resonant frequency of resonant cavity is constant.Described computing machine can be an ordinary PC, if the exploitation special product can wait with single-chip microcomputer, DSP and FPGA realizes.

According to top method, this professional those of ordinary skill just can be implemented the technology of the present invention, realizes goal of the invention.

Advantage of the present invention:

The subtle change that takes place on each organ volume such as monitoring plant root, stem, leaf that the present invention need not be traditional detects its water state changing taking, the method that detects its moisture state variation with the subtle change that takes place on each organ volumes such as monitoring plant root, stem, leaf compares, the present invention directly measures the moisture content change of plant roots, stem, leaf and monitors its moisture state variation, and measuring accuracy height, measurement range extensively, are not subjected to the influence of ergometry; With judge according to soil moisture plant whether lack of water method relatively, the present invention directly measures the moisture content change of plant roots, stem, leaf, can satisfy the requirement of plant precision irrigation system.The present invention can be directly adjacent to resonant cavity the determinand of growing up, as when adopting ring resonance, ring resonance is surrounded stem or the leaf for the treatment of measuring plants, when adopting planar shaped, curved resonant cavity, with close axis to be measured of resonant cavity or leaf, can carry out dynamic, harmless, detection in real time, can also connect irrigation system, carry out automatic irrigation.

Description of drawings

Fig. 1 is cylindrical metal resonant cavity and coordinate system thereof.

Fig. 2 is the experimental provision block scheme.

Fig. 3 is the relation of the resonant frequency and the substance moisture content content of resonant cavity.

Fig. 4 is the relation of Q-value of cavity and substance moisture content content.

Fig. 5 is the electromagnetic spectrum figure of Yunnan shrub seedling lack of water situation.

Fig. 6 is the electromagnetic spectrum figure of Yunnan cuckoo flower seedling lack of water situation.

Fig. 7 is the electromagnetic spectrum figure of Yunnan evergreen sapling lack of water situation.

Fig. 8 is Yunnan shrub seedling lack of water situation and the changing trend diagram of time.

Fig. 9 is Yunnan shrub seedling lack of water situation and the changing trend diagram of time.

Figure 10 is the apparatus structure synoptic diagram among the embodiment.

Figure 11 is the circuit block diagram among the embodiment.

Among the figure: 1-emission coefficient, 2-electromagnetic wave coupler device, 3-through hole, 4-receiving system, 5-interface, 6-computing machine, 7-resonant cavity.

Embodiment

Embodiment: see Figure 10 and Figure 11.

Computing machine 6 is by interface 5 control emission coefficients, emission coefficient 1 output frequency sweep electromagnetic wave, the frequency sweep electromagnetic wave enters metal resonant cavity 7 through coupling device 2, one through hole 3 is arranged in the resonance region chamber, this through hole provides the strong interaction district of resonant cavity and plant stem, electromagnetic wave after the effect is through coupling device 2 outputs, and the electromagnetic wave of coupling device output enters receiving system 4, and the signal after receiving system is handled enters computing machine 6 by interface 5.The information that Computer Processing receives gets final product the water shortage status of inverting plant.

In the present embodiment, the cylindrical metal resonant cavity is made up of two isopyknic semicolumns, and middle perforate, and the semicolumn height is 14mm, and inside radius is 48mm, and external radius is 52mm, and material is an invar, to guarantee good temperature stability; The microwave coupling device is the electric coupling rod, and the radius of electric coupling rod is 1mm, and long is 4mm; Through-hole diameter is 13mm; Emission coefficient is made up of frequency sweep circuit, control circuit, multifunction card and interface circuit; Interface circuit is respectively applied for computing machine is connected with receiving system with emission coefficient; Receiving system is made up of detecting circuit, amplifying circuit, multifunction card and interface circuit; Computing machine is an ordinary PC.

Above embodiment only is described further invention, and scope of the present invention is not subjected to the limitation of illustrated embodiment.

Claims (8)

1, a kind of electromagnetic wave resonance cavity method of accurate diagnosis of plant moisture is characterized in that being made up of following steps:

One, the strong interaction resonance region of electromagnetic wave and determinand is provided;

Two, read the resonant frequency that do not have determinand in the resonance region and the output voltage of electromagnetic wave signal by computing machine, and calculate its resonant frequency and Q value, tabulation deposits computing machine in, finishes the experiment set-up procedure;

Three, read the resonant frequency that determinand is arranged in the resonance region and the output voltage of electromagnetic wave signal by computing machine, and calculate its resonant frequency and Q value, tabulation deposits computing machine in;

Four, according to the output voltage of step 2 and three resonant frequency and electromagnetic wave signal can its moisture of inverting variation.

2, the electromagnetic wave resonance cavity method of accurate diagnosis of plant moisture as claimed in claim 1 is characterized in that described determinand is respectively root or stem or the leaf of plant.

3, the electromagnetic wave resonance cavity method of accurate diagnosis of plant moisture as claimed in claim 1 is characterized in that the resonance region that described resonance region is produced by the resonant cavity of excitation of electromagnetic wave.

4, the electromagnetic wave resonance cavity method of accurate diagnosis of plant moisture as claimed in claim 3 is characterized in that described resonance region is the distribution parameter resonance region.

5,, it is characterized in that described resonance region is open as the electromagnetic wave resonance cavity method of claim 1,3,4 described accurate diagnosis of plant moisture.

6, as the electromagnetic wave resonance cavity method of claim 1,3,4 described accurate diagnosis of plant moisture, it is characterized in that the temperature stability of described resonance region is good, when variation of ambient temperature, the resonant frequency of resonant cavity is constant.

7, the electromagnetic wave resonance cavity method of accurate diagnosis of plant moisture as claimed in claim 1 is characterized in that described computing machine is an ordinary PC.

8, the electromagnetic wave resonance cavity method of accurate diagnosis of plant moisture as claimed in claim 1 is characterized in that described computing machine is single-chip microcomputer or DSP.

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