Non-contact conductivity detection device and method for xylem of woody plant

Abstract

The invention discloses a non-contact type woody plant xylem conductivity detection device and method, and relates to the technical field of plant conductivity detection, and the device comprises an electrode module which comprises an excitation electrode and a detection electrode; the excitation electrode and the detection electrode are mounted on the plant skin; the controllable analog inductance circuit generates equivalent inductive reactance for eliminating capacitive reactance of the coupling capacitor; the resistance value of an adjustable component of the controllable analog inductance circuit can be controlled; the phase-sensitive demodulation module is used for feeding back the phase difference between the alternating-current excitation source and the output end of the controllable analog inductance circuit to the controller; the controller determines an adjustment target for the phase difference; the resistance value of the adjustable component is regulated and controlled based on the adjustment target, and when the difference value of the phase difference and the adjustment target value is within the allowable deviation range, the output result of the amplitude output end of the phase-sensitive demodulation module serves as the conductivity measurement result. And the adverse effect of the coupling capacitor can be adaptively eliminated.

Description

Technical Field

[0001] The present application relates to the technical field of plant conductivity detection, and in particular to a non-contact woody plant xylem conductivity detection device and method based on adaptive simulated inductance. Background Art

[0002] The stem of woody plants is mainly composed of the outer bark, phloem, xylem, and pith. Since the xylem is the main channel for plants to transport water, its moisture content and the changing characteristics of moisture content are closely related to plant growth and contain a lot of physiological information. Based on the close relationship between moisture content and conductivity, the moisture content of the xylem is often measured by conductivity detection, which has the advantages of fast response speed, simple device, easy installation, and easy integration. However, the existing conductivity-based xylem moisture content measurement method usually requires the detection electrode to be inserted into the plant, that is, piercing the outer bark and phloem so that the electrode is in direct contact with the xylem. This invasive measurement method has the following shortcomings: 1) It will cause plant damage and increase the risk of infection with various diseases; 2) After long-term measurement, the wound will produce wound repair tissue that destroys the measurement path; 3) The presence of the electrode will destroy the normal local water transport. Therefore, there is an urgent need for a woody plant xylem conductivity detection device that can achieve conductivity measurement without damaging the plant body (i.e., not directly contacting the xylem). Summary of the invention

[0003] The purpose of the present application is to provide a non-contact device and method for detecting the xylem conductivity of woody plants, which can measure the xylem conductivity of woody plants without damaging the plant body with electrodes and eliminate measurement errors.

[0004] To achieve the above objectives, this application provides the following solutions:

[0005] In a first aspect, the present application provides a non-contact woody plant xylem conductivity detection device, comprising an electrode module, a controllable analog inductance circuit, a controller, and a phase-sensitive demodulation module;

[0006] The electrode module includes an excitation electrode and a detection electrode; the excitation electrode and the detection electrode are installed on the plant skin along the growth direction of the woody plant stems;

[0007] The excitation electrode is connected to an AC excitation source, and the detection electrode is connected to an input end of the controllable analog inductance circuit;

[0008] The controllable analog inductance circuit is used to generate equivalent inductive reactance; the output end of the controllable analog inductance circuit is connected to the first input end of the phase-sensitive demodulation module; the controllable analog inductance circuit includes an adjustable component; the resistance value of the adjustable component is adjustable;

[0009] The phase-sensitive demodulation module is used to collect the phase difference between the AC excitation source and the output end of the controllable analog inductor circuit, and feed the phase difference back to the controller; the second input end of the phase-sensitive demodulation module is connected to the AC excitation source; the phase output end of the phase-sensitive demodulation module is connected to the controller;

[0010] The controller is used to: determine an adjustment target of the phase difference, and determine whether the difference between the phase difference and the adjustment target value is within an allowable deviation range; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range, adjust the resistance of the adjustable component in the controllable analog inductance circuit based on the adjustment target; when the difference between the phase difference and the adjustment target value is within the allowable deviation range, use the output result of the amplitude output end of the phase-sensitive demodulation module as the output conductivity measurement result of the xylem of the woody plant.

[0011] Optionally, the controllable simulated inductor circuit includes a first operational amplifier, a second operational amplifier, a third operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, an operational capacitor and an adjustable component;

[0012] The positive input terminals of the first operational amplifier and the second operational amplifier serve as the input terminals of the controllable analog inductor circuit; one terminal of the adjustable component is connected to the positive input terminal of the second operational amplifier, and the other terminal of the adjustable component is connected to the output terminal of the second operational amplifier; the adjustable component is connected to the controller; one terminal of the third resistor is connected to the inverting input terminal of the second operational amplifier, and the other terminal of the third resistor is connected to the output terminal of the second operational amplifier; one terminal of the second resistor is connected to the output terminal of the first operational amplifier, and the other terminal of the second resistor is connected to the inverting input terminal of the second operational amplifier; one terminal of the operational capacitor is connected to the inverting input terminal of the first operational amplifier, and the other terminal of the operational capacitor is connected to the output terminal of the first operational amplifier; one terminal of the first resistor is connected to the inverting input terminal of the first operational amplifier, and the other terminal of the first resistor is connected to the inverting input terminal of the third operational amplifier; the positive input terminal of the third operational amplifier is grounded; one terminal of the fourth resistor is connected to the inverting input terminal of the third operational amplifier, and the other terminal of the fourth resistor is connected to the output terminal of the three operational amplifiers; the output terminal of the three operational amplifiers is the output terminal of the controllable analog inductor circuit;

[0013] The third operational amplifier converts the current flowing through the first resistor into a voltage signal and transmits it to the phase-sensitive demodulation module.

[0014] Optionally, the adjustable component includes a first digital potentiometer and a second digital potentiometer; one end of the first digital potentiometer is connected to the second digital potentiometer, and the other end of the first digital potentiometer is connected to the non-inverting input end of the second operational amplifier; one end of the second digital potentiometer is connected to the second digital potentiometer, and the other end of the second digital potentiometer is connected to the output end of the second operational amplifier.

[0015] Optionally, the controller is used to: when the difference between the phase difference and the adjustment target value is greater than a set value, adjust the resistance of the first digital potentiometer; when the difference between the phase difference and the adjustment target value is less than a set value, adjust the resistance of the second digital potentiometer.

[0016] Optionally, the controller is used to: increase the resistance of the adjustable component when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is smaller than the adjustment target value; and reduce the resistance of the adjustable component when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is larger than the adjustment target value.

[0017] Optionally, the adjustment target value of the phase difference is -90°.

[0018] In a second aspect, the present application provides a non-contact woody plant xylem conductivity detection method based on the above-mentioned non-contact woody plant xylem conductivity detection device, comprising:

[0019] Obtaining a phase difference between an AC excitation source and an output end of a controllable simulated inductor circuit;

[0020] Determining an adjustment target of the phase difference, and judging whether a difference between the phase difference and the adjustment target value is within an allowable deviation range;

[0021] When the difference between the phase difference and the adjustment target value is not within the allowable deviation range, adjusting the resistance value of the adjustable component in the controllable simulated inductor circuit;

[0022] When the difference between the phase difference and the adjustment target value is within the allowable deviation range, the output result of the amplitude output terminal of the phase-sensitive demodulation module is used as the output conductivity measurement result of the xylem of the woody plant.

[0023] Optionally, the adjustable component includes a first digital potentiometer and a second digital potentiometer; when the difference between the phase difference and the adjustment target value is greater than a set value, the resistance of the first digital potentiometer is adjusted; when the difference between the phase difference and the adjustment target value is less than the set value, the resistance of the second digital potentiometer is adjusted.

[0024] Optionally, when the difference between the phase difference and the adjustment target value is not within the allowable deviation range, regulating the resistance of the adjustable component in the controllable simulated inductor circuit specifically includes:

[0025] When the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is smaller than the adjustment target value, the resistance of the adjustable component is increased; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is larger than the adjustment target value, the resistance of the adjustable component is reduced.

[0026] Optionally, the non-contact woody plant xylem conductivity detection method also includes: when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is less than the adjustment target value, increasing the resistance of the adjustable component; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is greater than the adjustment target value, reducing the resistance of the adjustable component.

[0027] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0028] The present application provides a non-contact xylem conductivity detection device and method for woody plants. Non-invasive electrodes are installed on the plant bark to achieve non-invasive measurement of the xylem conductivity of the plant through AC excitation. The phase difference between the AC excitation source input and the output of a controllable analog inductance circuit is obtained through a phase-sensitive demodulation circuit, and the phase difference is input into a controller as a feedback signal to form a negative feedback automatic control system with the difference between the phase difference and the adjustment target value within an allowable deviation range as a control target. By adjusting the resistance of an adjustable component in the controllable analog inductance circuit, the control target of the difference between the phase difference and the adjustment target value within the allowable deviation range is achieved, so as to eliminate the measurement error caused by the growth of the xylem of the woody plant itself, and the xylem conductivity measurement of the woody plant can be achieved without damaging the plant body by the electrode, and the adverse effects of coupling capacitance can be adaptively eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 Schematic diagram of the non-contact conductivity detection (CCD) technology principle provided in this application.

[0031] Figure 2 for Figure 1 Schematic diagram of the equivalent circuit.

[0032] Figure 3 This is a schematic structural diagram of the non-contact woody plant xylem conductivity detection device provided in Example 1 of the present application.

[0033] Figure 4 This is a circuit diagram of the non-contact woody plant xylem conductivity detection device provided in Example 1 of the present application.

[0034] Figure 5 A schematic flow chart of a non-contact method for detecting xylem conductivity of woody plants provided in Example 2 of the present application.

[0035] Reference numerals:

[0036] AC excitation source—1, excitation electrode—2, plant stem—3, detection electrode—4, controllable analog inductance circuit—5. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0039] The non-contact conductivity detection (CCD) technology used in non-metallic pipes in industry provides a possibility and reference for realizing such a non-invasive xylem conductivity measurement. The basic principle of the existing CCD technology is as follows: Figure 1 , its equivalent circuit is as follows Figure 2 As shown. It mainly includes an AC excitation source 1, an insulated measuring pipe, a measured fluid, an excitation electrode 2, a detection electrode 4 and a signal processing circuit. When an AC excitation signal is applied to the excitation electrode 2, the excitation electrode 2 and the detection electrode 4 form a coupling capacitance C with the measured fluid respectively. p1 and C p2 , and then the equivalent conductivity R of the fluid in the tube E An AC measurement path is formed, so that the conductivity of the fluid in the pipe can be measured through the insulating pipe wall without contacting the measured fluid. However, the existing CID technology cannot be directly used for measuring the conductivity of plant xylem. The reason is that in industry, pipelines are artificial and rigid, so their pipeline parameters (including pipe wall thickness, pipe diameter, pipe material, etc.) and working environment are constants in most measurement scenarios and will not change with the measurement process. The corresponding coupling capacitance formed is also constant. At this time, the measured signal change is completely caused by the change in the conductivity of the fluid in the pipe.

[0040] In plants, it is completely different. The change in xylem conductivity depends on the conductivity σ of the internal liquid and the liquid content α% of the xylem. The above two parameters are the effective information of xylem conductivity that needs to be detected. However, if the CID technology is used directly, the measured signal change will be affected by other factors in addition to the conductivity σ and the liquid content α% of the xylem, such as the collapse or swelling of the xylem tracheid and the vessel caused by the change in water content, the change in epidermal thickness caused by plant growth, and the change in dielectric constants of the epidermis, phloem, etc. caused by the external environment. All of these changes will cause changes in coupling capacitance, and these changes are uncontrollable in the measurement and will also cause fluctuations in the measurement signal. This part of the signal is noise and error for conductivity measurement and needs to be eliminated. Therefore, it is necessary to design a controllable analog inductor circuit 5 circuit that can adaptively eliminate the measurement errors caused by these uncontrollable coupling capacitors during the measurement process to achieve effective measurement of xylem conductivity.

[0041] Example 1

[0042] like Figure 3 As shown, this embodiment provides a non-contact woody plant xylem conductivity detection device, including an electrode module, a controllable analog inductance circuit 5, a controller and a phase-sensitive demodulation module.

[0043] The electrode module includes two non-invasive electrodes, namely an excitation electrode 2 and a detection electrode 4; the excitation electrode 2 and the detection electrode 4 are installed on the plant skin along the growth direction of the woody plant stem 3. The excitation electrode 2 is connected to the AC excitation source 1, and the detection electrode 4 is connected to the input end of the controllable analog inductance circuit 5. Two non-invasive electrodes are installed on the plant skin along the growth direction of the stem using non-destructive methods including pasting, snap fixing, clamping, bundling, etc. The excitation electrode 2 and the detection electrode 4 respectively form a first coupling capacitor C with the wood part of the woody plant under test. p1 and the second coupling capacitor C p2 , and the equivalent conductivity R of the xylem of the woody plant under test eq Constitute an AC measurement path.

[0044] The controllable analog inductor circuit 5 is used to generate an equivalent inductive reactance; the output end of the controllable analog inductor circuit 5 is connected to the first input end X of the phase-sensitive demodulation module. in connected; the controllable simulated inductance circuit 5 includes an adjustable component; the resistance of the adjustable component is adjustable.

[0045] like Figure 4 As shown, the controllable simulated inductor circuit 5 includes a first operational amplifier A 1 , the second operational amplifier A 2 , the third operational amplifier A 3 , the first resistor R 1 , the second resistor R 2 , the third resistor R 3, the fourth resistor R f , operational capacitor C s and adjustable components, three operational amplifiers and the first operational amplifier A 1 , the second operational amplifier A 2 , the third operational amplifier A 3 The peripheral components of the controllable impedance converter are based on the classic Riordan analog inductor circuit. C The input end is connected to the detection electrode 4, and the output end is connected to the third operational amplifier A 3 The current-to-voltage converter is formed by using a third operational amplifier A 3 The virtual short effect is achieved to achieve a potential of 0 at one end to ensure the normal operation of the Riordan analog inductor circuit; the third operational amplifier A 3 A current-to-voltage converter is formed to convert the current flowing through the first resistor R 1 The current is converted into a voltage signal and transmitted to the phase-sensitive demodulation module.

[0046] The first operational amplifier A 1 and the second operational amplifier A 2 The positive phase input terminal of the controllable analog inductor circuit 5 is used as the input terminal; one end of the adjustable component is connected to the second operational amplifier A 2 The other end of the adjustable component is connected to the non-inverting input terminal of the second operational amplifier A 2 The adjustable component is connected to the controller; the third resistor R 3 One end of the second operational amplifier A 2 The inverting input terminal is connected to the third resistor R 3 The other end is connected to the second operational amplifier A 2 The output end is connected to the second resistor R 2 One end of the first operational amplifier A 1 The output terminal is connected to the second resistor R 2 The other end is connected to the second operational amplifier A 2 The inverting input terminal is connected to the operational capacitor C s One end of the first operational amplifier A 1 The inverting input terminal is connected to the operational capacitor C s The other end is connected to the first operational amplifier A 1 The output end is connected to the first resistor R 1 One end of the first operational amplifier A 1 The inverting input terminal is connected to the first resistor R 1 The other end is connected to the third operational amplifier A 3 The inverting input terminal of the third operational amplifier A 3 The positive input terminal of the fourth resistor R fOne end of the third operational amplifier A 3 The inverting input terminal is connected to the fourth resistor R f The other end is connected to the output end of the three operational amplifiers; the output end of the three operational amplifiers is the output end of the controllable analog inductor circuit 5.

[0047] The third operational amplifier A 3 The current flowing through the first resistor R 1 The current is converted into a voltage signal and transmitted to the phase-sensitive demodulation module.

[0048] The adjustable component includes a first digital potentiometer R x1 and the second digital potentiometer R x2 ; The first digital potentiometer R x1 One end of the second digital potentiometer R x2 Connect the first digital potentiometer R x1 The other end is connected to the second operational amplifier A 2 The second digital potentiometer R x2 One end of the second digital potentiometer R x2 Connect the second digital potentiometer R x2 The other end is connected to the second operational amplifier A 2 The output end of the first digital potentiometer R x1 A 0-10kΩ digital potentiometer X9C103 can be used, and the second digital potentiometer R x2 A 0-1kΩ digital potentiometer X9C102 can be used.

[0049] The phase-sensitive demodulation module is used to collect the phase difference between the AC excitation source 1 and the output end of the controllable analog inductor circuit 5, and feed the phase difference back to the controller; the second input end Y in It is connected to the AC excitation source 1; and the phase output terminal Pha of the phase-sensitive demodulation module is connected to the controller.

[0050] The phase output terminal Pha of the phase-sensitive demodulation module is connected to the analog-to-digital conversion input terminal of the controller as a feedback signal. The controller automatically adjusts the control parameters according to the feedback signal, changes the equivalent inductance of the controllable analog inductance circuit 5, and maintains the series resonance state of the measurement path. The amplitude output terminal Amp of the phase-sensitive demodulation module is output as the conductivity detection result.

[0051] The controller is used to: determine the adjustment target of the phase difference, and determine whether the difference between the phase difference and the adjustment target value is within the allowable deviation range; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range, adjust the resistance of the adjustable component in the controllable analog inductance circuit 5 based on the adjustment target; when the difference between the phase difference and the adjustment target value is within the allowable deviation range, use the output result of the amplitude output terminal Amp of the phase-sensitive demodulation module as the output conductivity measurement result of the xylem of the woody plant.

[0052] When the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is less than the adjustment target value, the resistance of the adjustable component is increased; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is greater than the adjustment target value, the resistance of the adjustable component is reduced.

[0053] Figure 4 The output U of the controllable simulated inductor circuit 5 is shown out With AC excitation source 1 input U in The relationship is shown in the following formula.

[0054]

[0055] In the formula, and are the phasor forms of the input signal and the output signal, respectively, R f is the resistance of the fourth resistor, R 1 is the resistance of the first resistor, j is the imaginary unit, f is the excitation frequency, C p1 and C p2 are the capacitance values ​​of the first coupling capacitor and the second coupling capacitor, R eq is the equivalent conductivity of the xylem of the woody plant under test, L C is the equivalent inductive reactance value generated by the controllable simulated inductor circuit 5, which is specifically expressed by the following formula:

[0056]

[0057] In the formula, R 2 ,R 3 are the resistance values ​​of the second resistor and the third resistor respectively, C s is the capacitance value of the operational capacitor, R x1 and R x2 are the resistances of the first digital potentiometer and the second digital potentiometer, respectively, and their values ​​are controlled by a single chip microcomputer or other controller program. According to formula (1), when the following conditions are met, the circuit reaches series resonance.

[0058]

[0059] Let formula (3) be the series resonance condition, and then formula (1) becomes:

[0060]

[0061] That is, at this time and output The only unknown quantity is the conductivity value R. eq , the effect of coupling capacitance on measurement can be eliminated. When the coupling capacitance changes due to various reasons, the series resonance condition described by formula (3) will be broken, resulting in measurement errors. According to formula (3), the excitation frequency f or the equivalent inductive reactance value L can be adjusted C So that the series resonance condition is satisfied again. However, in plant detection, since its equivalent electrical model is more complex than that of industrial fluid, changing the excitation frequency f will introduce new uncontrollable variables and increase the uncertainty of measurement; at the same time, changing the excitation frequency f will put higher requirements on the subsequent signal processing circuit and signal source circuit. Therefore, this embodiment chooses to change the equivalent inductance value L C , so that the series resonance condition is always satisfied. According to formula (2), the first digital potentiometer R can be adjusted by the controller x1 and the second digital potentiometer R x2 The resistance value of the first digital potentiometer R is adjusted so that the series resonance condition is always satisfied. This embodiment is divided into coarse adjustment and fine adjustment. When the difference between the phase difference and the adjustment target value is greater than the set value, the first digital potentiometer R is adjusted. x1 When the difference between the phase difference and the adjustment target value is less than the set value, adjust the second digital potentiometer R x2 resistance value.

[0062] The phase-sensitive demodulation module can be implemented using the gain phase detector AD8302. in and Y in Connect the third operational amplifier A 3 The output and AC excitation source 1 output, its two output ends respectively output the phase measurement result Pha and the amplitude measurement result Amp, the phase measurement result is connected to the input end of the controller as a feedback signal, and the amplitude measurement result is connected to the subsequent data acquisition link as the conductivity measurement result of the xylem of the woody plant.

[0063] In a specific example, the adjustment target value may be -90°. The phase difference between the input of the AC excitation source 1 and the output of the controllable analog inductor circuit 5 is obtained through a phase-sensitive demodulation circuit. The phase difference is input into the controller as a feedback signal, and the phase difference setting value of the series resonance state is -90° according to formula (4). If the coupling capacitor changes, the series resonance condition is not met, and the corresponding phase difference is not -90°. The adjustment target value is compared with the measured value to produce a deviation. According to the phase difference, the controller adjusts the controlled object. If the phase difference is less than -90°, it means that the phase of formula (3) is less than 0, and the measurement circuit is capacitive, then the controllable analog inductor value is increased, that is, the resistance of the digital potentiometer is increased. On the contrary, if the phase difference is greater than -90°, it means that the phase of formula (3) is greater than 0, and the measurement circuit is inductive, then the controllable analog inductor value is reduced, that is, the resistance of the digital potentiometer is reduced.

[0064] Until the phase difference is maintained within the allowable deviation range of -90°±ε, where ε is the allowable deviation. This is because the digital potentiometer changes discretely, so it cannot be guaranteed that the phase difference is exactly equal to -90° in all cases.

[0065] This embodiment has the following advantages:

[0066] 1) Install non-invasive electrodes on the plant skin and use AC excitation to achieve non-invasive measurement of plant xylem conductivity. Advantages: The xylem conductivity of plants can be measured non-invasively without causing damage to the plants. It can also avoid problems such as interference with growth and measurement affected by injury effects caused by invasive measurements.

[0067] 2) Use the digital potentiometer chips X9C102 and X9C103 to combine into a 0Ω to 11kΩ, 10Ω resolution digital potentiometer module to replace the ground resistor in the basic Riordan circuit to achieve programmable control of the equivalent inductance value. Advantages: The equivalent inductance value of the analog inductor can be automatically controlled by the program.

[0068] 3) The phase difference between the input of the AC excitation source 1 and the output of the controllable analog inductance circuit 5 (sensor) is obtained through the phase-sensitive demodulation module, and the phase difference is input as a feedback signal to the inductance value controller of the equivalent inductance, forming a negative feedback automatic control system with a phase difference of 0 as the control target. If the phase difference is greater than zero, the analog inductance value is reduced, and if it is less than zero, the analog inductance value is increased.

[0069] 4) The inductance of the controllable analog inductor automatically changes with the change of the capacitive reactance of the coupling capacitor. Through the phase difference negative feedback loop, the input excitation signal of the controllable analog inductor circuit 5 is controlled to always be in phase with its output signal, ensuring that the controllable analog inductor circuit 5 is always in a series resonance state, adaptively eliminating the measurement error caused by the uncontrollable fluctuation of the coupling capacitor, and improving the signal-to-noise ratio and accuracy of the plant xylem conductivity measurement. Advantages: The measurement circuit can always be in a series resonance state, and it will automatically adjust even if the coupling capacitor changes, ensuring that the physiological and morphological changes of the plant will not interfere with the measurement of the xylem conductivity during long-term measurement, and improving the stability and robustness of the measurement.

[0070] Example 2

[0071] like Figure 5 As shown, this embodiment provides a non-contact woody plant xylem conductivity detection method based on the above-mentioned non-contact woody plant xylem conductivity detection device, including the following steps.

[0072] S1: Obtaining the phase difference between the AC excitation source 1 and the output end of the controllable analog inductor circuit 5.

[0073] S2: Determine an adjustment target of the phase difference, and determine whether a difference between the phase difference and the adjustment target value is within an allowable deviation range.

[0074] S3: When the difference between the phase difference and the adjustment target value is not within the allowable deviation range, adjusting the resistance value of the adjustable component in the controllable simulated inductor circuit 5 .

[0075] S4: When the difference between the phase difference and the adjustment target value is within the allowable deviation range, the output result of the amplitude output terminal Amp of the phase-sensitive demodulation module is used as the output conductivity measurement result of the xylem of the woody plant.

[0076] As an optional embodiment, the adjustable component includes a first digital potentiometer R x1 and the second digital potentiometer R x2 When the difference between the phase difference and the adjustment target value is greater than the set value, the first digital potentiometer R is adjusted x1 When the difference between the phase difference and the adjustment target value is less than the set value, the second digital potentiometer R is adjusted x2 resistance value.

[0077] S3 specifically includes: when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is smaller than the adjustment target value, increasing the resistance of the adjustable component; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is larger than the adjustment target value, reducing the resistance of the adjustable component.

[0078] When the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is smaller than the adjustment target value, the resistance of the adjustable component is increased; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is larger than the adjustment target value, the resistance of the adjustable component is reduced.

[0079] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A non-contact woody plant xylem conductivity detection device, characterized in that: The non-contact woody plant xylem conductivity detection device comprises an electrode module, a controllable analog inductance circuit, a controller and a phase-sensitive demodulation module; The electrode module includes an excitation electrode and a detection electrode; the excitation electrode and the detection electrode are installed on the plant skin along the growth direction of the woody plant stems; The excitation electrode is connected to an AC excitation source, and the detection electrode is connected to an input end of the controllable analog inductance circuit; The controllable analog inductance circuit is used to generate equivalent inductive reactance; the output end of the controllable analog inductance circuit is connected to the first input end of the phase-sensitive demodulation module; the controllable analog inductance circuit includes an adjustable component; the resistance value of the adjustable component is adjustable; The phase-sensitive demodulation module is used to collect the phase difference between the AC excitation source and the output end of the controllable analog inductor circuit, and feed the phase difference back to the controller; The second input terminal of the phase-sensitive demodulation module is connected to the AC excitation source; the phase output terminal of the phase-sensitive demodulation module is connected to the controller; The controller is used to: determine an adjustment target of the phase difference, and determine whether the difference between the phase difference and the adjustment target value is within an allowable deviation range; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range, adjust the resistance of the adjustable component in the controllable analog inductance circuit based on the adjustment target; when the difference between the phase difference and the adjustment target value is within the allowable deviation range, use the output result of the amplitude output end of the phase-sensitive demodulation module as the output conductivity measurement result of the xylem of the woody plant.

2. The non-contact woody plant xylem conductivity detection device according to claim 1, characterized in that: The controllable simulated inductor circuit includes a first operational amplifier, a second operational amplifier, a third operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, an operational capacitor and an adjustable component; The positive input terminals of the first operational amplifier and the second operational amplifier serve as the input terminals of the controllable analog inductor circuit; one terminal of the adjustable component is connected to the positive input terminal of the second operational amplifier, and the other terminal of the adjustable component is connected to the output terminal of the second operational amplifier; the adjustable component is connected to the controller; one terminal of the third resistor is connected to the inverting input terminal of the second operational amplifier, and the other terminal of the third resistor is connected to the output terminal of the second operational amplifier; one terminal of the second resistor is connected to the output terminal of the first operational amplifier, and the other terminal of the second resistor is connected to the inverting input terminal of the second operational amplifier; one terminal of the operational capacitor is connected to the inverting input terminal of the first operational amplifier, and the other terminal of the operational capacitor is connected to the output terminal of the first operational amplifier; one terminal of the first resistor is connected to the inverting input terminal of the first operational amplifier, and the other terminal of the first resistor is connected to the inverting input terminal of the third operational amplifier; the positive input terminal of the third operational amplifier is grounded; one terminal of the fourth resistor is connected to the inverting input terminal of the third operational amplifier, and the other terminal of the fourth resistor is connected to the output terminal of the three operational amplifiers; the output terminal of the three operational amplifiers is the output terminal of the controllable analog inductor circuit; The third operational amplifier converts the current flowing through the first resistor into a voltage signal and transmits it to the phase-sensitive demodulation module.

3. The non-contact woody plant xylem conductivity detection device according to claim 2, characterized in that: The adjustable component includes a first digital potentiometer and a second digital potentiometer; one end of the first digital potentiometer is connected to the second digital potentiometer, and the other end of the first digital potentiometer is connected to the non-inverting input end of the second operational amplifier; one end of the second digital potentiometer is connected to the second digital potentiometer, and the other end of the second digital potentiometer is connected to the output end of the second operational amplifier.

4. The non-contact woody plant xylem conductivity detection device according to claim 3, characterized in that: The controller is used to: when the difference between the phase difference and the adjustment target value is greater than a set value, adjust the resistance of the first digital potentiometer; when the difference between the phase difference and the adjustment target value is less than the set value, adjust the resistance of the second digital potentiometer.

5. The non-contact woody plant xylem conductivity detection device according to claim 1, characterized in that: The controller is used to: when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is smaller than the adjustment target value, increase the resistance of the adjustable component; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is larger than the adjustment target value, reduce the resistance of the adjustable component.

6. The non-contact woody plant xylem conductivity detection device according to claim 1, characterized in that: The adjustment target value of the phase difference is -90°.

7. A non-contact woody plant xylem conductivity detection method based on the non-contact woody plant xylem conductivity detection device according to any one of claims 1 to 6, characterized in that: The non-contact woody plant xylem conductivity detection method comprises: Obtaining a phase difference between an AC excitation source and an output end of a controllable simulated inductor circuit; Determining an adjustment target of the phase difference, and judging whether a difference between the phase difference and the adjustment target value is within an allowable deviation range; When the difference between the phase difference and the adjustment target value is not within the allowable deviation range, adjusting the resistance value of the adjustable component in the controllable simulated inductor circuit; When the difference between the phase difference and the adjustment target value is within the allowable deviation range, the output result of the amplitude output terminal of the phase-sensitive demodulation module is used as the output conductivity measurement result of the xylem of the woody plant.

8. The non-contact woody plant xylem conductivity detection method according to claim 7, characterized in that: The adjustable component includes a first digital potentiometer and a second digital potentiometer; when the difference between the phase difference and the adjustment target value is greater than a set value, the resistance value of the first digital potentiometer is adjusted; when the difference between the phase difference and the adjustment target value is less than the set value, the resistance value of the second digital potentiometer is adjusted.

9. The non-contact woody plant xylem conductivity detection method according to claim 7, characterized in that: When the difference between the phase difference and the adjustment target value is not within the allowable deviation range, regulating the resistance value of the adjustable component in the controllable simulated inductor circuit specifically includes: When the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is smaller than the adjustment target value, the resistance of the adjustable component is increased; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is larger than the adjustment target value, the resistance of the adjustable component is reduced.

10. The non-contact woody plant xylem conductivity detection method according to claim 7, characterized in that: The non-contact woody plant xylem conductivity detection method further comprises: When the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is smaller than the adjustment target value, the resistance of the adjustable component is increased; when the difference between the phase difference and the adjustment target value is not within the allowable deviation range and the phase difference is larger than the adjustment target value, the resistance of the adjustable component is reduced.

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