CN101666768A - Multichannel electrical impedance type plant water content monitoring system - Google Patents
Multichannel electrical impedance type plant water content monitoring system Download PDFInfo
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- CN101666768A CN101666768A CN200910093917A CN200910093917A CN101666768A CN 101666768 A CN101666768 A CN 101666768A CN 200910093917 A CN200910093917 A CN 200910093917A CN 200910093917 A CN200910093917 A CN 200910093917A CN 101666768 A CN101666768 A CN 101666768A
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Abstract
The invention relates to a multichannel electrical impedance type plant water content monitoring system which comprises a hardware circuit, a measuring probe and a personal computer part. The multichannel electrical impedance type plant water content monitoring system is characterized in that the hardware circuit comprises a USB power supply module, a data transmission and control module and an impedance measuring module, wherein the USB power supply module supplies power to the hardware circuit after being connected with a personal computer; the data transmission and control module realizes channel gating switch control and data transmission; the impedance measuring module generates a frequency adjustable sinusoidal wave as an exciting source by a direct frequency synthesizing chip and obtains an impedance value by a self-balancing bridge circuit comprising an amplifier and a feedback resistor through analog multiplication and low-pass filtration, analogue-to-digital conversion and data processing; the measuring probe consists of a single-core shielded wire and a lamellar electrode; and the personal computer part is a control procedure interface, controls the hardware circuit andprocesses and displays measured data. The invention ensures simultaneous measure of multiple channels and has the advantages of non-invasive and long-term continuous monitoring, and the like.
Description
[technical field]
The present invention relates to a kind of monitoring system, specifically is a kind of multichannel electrical impedance type plant water content monitoring system.
[background technology]
Agricultural irrigation is with a long history, and the technical matters relevant with irrigation paid attention to by people always.China's agricultural water accounts for 80% of annual total water amount, but the utilization factor of irrigation water has only 40%, one side water resource anxiety, and water is again in waste on the one hand.The high-efficiency water-saving agricultural of now carrying out comprises that reducing water delivery loses (anti-seepage of channels, pipeline water delivery), adopts advanced irrigation method (sprinkling irrigation, drip irrigation) and other agricultural water conservation measures (covering with ground sheeting, seed selection drought-enduring variety) etc.When implement irrigating, the key of high yield water-saving irrigation is the depletion diagnosis, in time pours water by depletion information in need water tricky time.
To the diagnosis of crop damage caused by a drought is not only ancient but also novel problem, domestic diagnosis to plant hydropenia at present mainly is according to soil moisture, other also has leaf temperature, blade face transpiration rate, soil water potential, the little contraction of stem stalk (or fruit) etc., back several method ubiquity resolution is not high, is subject to defectives such as external interference.The way of comparative maturity is to diagnose damage caused by a drought with soil moisture content, and it is accurately easily gone, but because the baking loaded down with trivial details time of native test method is long, diagnosis lags behind untimely.From the plant physiology arid plant body fluid physicochemical property is changed, body fluid makes increase, certainty reflect to some extent on the physiology electrical characteristics, and this paper judges the plant water content situation from stem stalk physiology electrical impedance characteristics aspect.There is article to propose to measure water percentage in the plant indirectly with the way of measuring plant haulm two ends impedance value, but this method will be broken apart by chopping plant, get the experiment of its stem stalk, plant is caused expendable damage, the method is infeasible for the bigger plant of negligible amounts and individual difference; Also there is patent " plant moisture percentage measuring apparatus " (ZL 200720103410.4) to take to measure the mode of plant haulm electrical impedance with ring-shaped probe, this device has been accomplished simple to operate, easy to carry, but it adopts powered battery and has only one to measure passage, can not realize long-time monitoring to plant different piece or different plants, and metering system belongs to intrusive mood, and plant is had damage.
In view of above situation, the present invention adopts non-invasive impedance bioelectrical measurement method, except that can onlinely judging plant whether the lack of water, also can be to the long-time monitoring of plant obtaining the variation tendency of its inner water percentage, but and hyperchannel measure simultaneously, play the effect of contrast.
[summary of the invention]
The present invention is an a kind of plant water content variation monitoring system, mainly utilizes the mode of impedance bioelectrical measurement, and the corresponding relation of the impedance value water percentage inner with it by plant is measured the situation of change of inside plants water percentage.
A kind of multichannel electrical impedance type plant water content monitoring system provided by the invention is by the following technical solutions:
Comprise hardware circuit, measuring sonde 201 and PC part 101; It is characterized in that described hardware circuit comprises USB supply module 103, data transmission and control module 107, driving source generation module 108, metering circuit module 110, multiplication demodulation and low-pass filtering module 113 and analog-to-digital conversion module 116; USB supply module 103 is connected the back and powers to hardware circuit with PC 101, data transmission and control module 107 realize control of passage gating switch and data transmission, the impedance measurement module adopts direct frequency synthesis chip to produce the sine wave of frequency adjustable as driving source, self-balancing bridge circuit through operational amplifier and feedback resistance formation, by analogue multiplication and low-pass filtering, finally after analog to digital conversion, data processing, obtain resistance value; Described measuring sonde 201 adopts single-core shielding line and pellet electrode; Described PC part 101 is the control program interface, realizes the control of hardware circuit and the processing and the demonstration of measurement data.
Wherein, described hardware circuit part comprises USB supply module 103, data transmission and control module 107, driving source generation module 108, measurement module 110, multiplication demodulation module 113 and analog-to-digital conversion module 116.Described USB supply module 103 links to each other with PC 101 by usb data line 102, utilize that data line provides+5V voltage and through voltage transitions chip 105 and 106 obtain respectively+3.3V powers to hardware circuit with ± 15V voltage.
Wherein, described data transmission and control module 107, adopt the control core of the EZ-USB FX2 series monolithic of Cypress company production as system, realize the switching gate of control survey passage, control the adjustable sine wave of described driving source generation module 108 output frequencies, for providing the digital quantity input as the digital to analog converter 112 of equivalent feedback resistance in the described measurement module 110, and the digital data that obtains in the described analog-to-digital conversion module 116 is transferred to PC 101 by usb data line 102 handles.
Wherein, described driving source generation module 108 adopts direct frequency synthesis chip, and this chip mainly partly is made of Direct Digital synthesis system able to programme, high-performance A-D converter, realizes the frequency synthesis of digital programming Control.Be written into mode by the control word serial and produce complementary two-way current output signal, again through the current/voltage-converted circuit, adopting the form of difference is excitation and the reference signal of voltage signal as measuring system with two-way complementary current conversion of signals.
Wherein, described measurement module 110 is operational amplifier 111 and the self-balancing bridge circuit that constitutes as the digital to analog converter 12 of feedback resistance, the backfeed loop that digital to analog converter 112 is connected on self-balancing bridge can equivalence be feedback resistance, the equivalence resistance is controlled by the digital quantity of described data transmission and control module 7 inputs, can in the scope of 10k Ω to 3M Ω, regulate, and have good linearty.Change the gain of measurement module 110 by regulating the feedback resistance, and then expand the dynamic range of described analog-to-digital conversion module 116.
Wherein, described multiplication demodulation module 113 is made up of analog multiplier 114 and low-pass filter 115, the voltage excitation signals that described excitation generation module 108 produces is as the reference signal, signal behind the described measurement module 110 of process is as measuring-signal, this two paths of signals is the input of analog multiplier 114, and the output of analog multiplier 114 enters described analog-to-digital conversion module 116 behind low-pass filter 115.
Wherein, described analog-to-digital conversion module 116 is 12 high-speed AD converters, is the simulating signal that measures that 12 bit digital quantity are imported described data transmission module 107 into and data are sent to host computer and handle with higher rate conversion.
Wherein, described measuring sonde 201 comprises shielding line and electrode, shielding line can reduce the interference of extraneous spurious signal, potential electrode be to can non-invasively placing different parts of plant or the same area of different plants, and the electrical impedance of the same area by each position of plant or different plants changes the water percentage that reflects plant and changes and health status.
Wherein, described PC part 101 is pc control procedure and interface, can write realization with Visual Basic, Visual C, Labview etc.Pc control procedure is at first controlled the sine voltage signal that described voltage drive module 108 produces required frequency, data that produce according to the described analog-to-digital conversion module that receives 116 again, regulate the equivalent resistance of the digital to analog converter 12 in the described measurement module 110, make it and be complementary by the electrical impedance of measuring plants to obtain the high-acruracy survey result, at last host computer realize measurement result storage, handle and demonstration.
Beneficial effect of the present invention: the present invention designs a kind of measuring system of coming on-line monitoring inside plants water percentage to change by multi-channel measurement plant haulm electrical impedance, and is simple in structure, and the cost performance height is fit to the experimental plot and uses.And because this method is a non-intruding, online, multichannel, so can be nondestructively the water percentage variation of monitoring plant different parts or different plants in real time, judge the whether purpose of lack of water and monitoring plant health status of plant to reach.
[Figure of description]
Fig. 1 is that multichannel electrical impedance type plant water content measure of the change system composition shows block diagram;
Fig. 2 is measuring sonde and metering system synoptic diagram thereof;
Fig. 3 is voltage source excitation blocks current/voltage conversion circuit schematic diagram.
[embodiment]
Hardware circuit links to each other with described PC part 101 by usb data line 102, usb data line 102 provides+and 5V voltage is as the power supply of hardware circuit, + 5V voltage obtains the supply voltage of 3.3V voltage as most of digit chip of hardware circuit by described voltage transitions chip 105, as analog device power supplys such as operational amplifier ± 15V voltage produces by voltage transitions chip 106 by+5V voltage.
Described data transmission and control module 107 are given in the order of host computer transmitting system excitation frequency, make it control described driving voltage generation module 108 and produce the sinusoidal current signal of the two-way complementation of corresponding frequencies, with reference to Fig. 3, this two-way current signal adopts the mode of difference to produce the voltage drive source of the sine voltage signal of same frequency as system by the current/voltage-converted circuit.This pumping signal is divided into two, and a part obtains measuring-signal by described measurement module 110 and as the input of analog multiplier 114 in described multiplication demodulation and the filtration module 113, another road as the reference signal directly as the input of analog multiplier 114.
Described voltage drive source signal is received the inverting input of operational amplifier 111 in the described measurement module 110, the in-phase input end ground connection of operational amplifier 111 by object under test 109; The reference voltage input terminal of digital to analog converter 112 links to each other with the output terminal of operational amplifier 111, and current output terminal links to each other with the inverting input of operational amplifier 111.Under such connection, digital to analog converter 112 plays the effect of feedback resistance, has constituted the self-balancing bridge circuit with operational amplifier 111, and this circuit can reduce the interference of lead capacitance and other stray capacitance to a great extent.Digital to analog converter 112 as the benefit of feedback resistance is: can regulate the digital quantity input of digital to analog converter 112 by described data transmission and control module 7, and then the size of change digital to analog converter 112 equivalent resistances, accomplish coupling to greatest extent with object under test 109 input impedance.So can expand the responding range of described analog-to-digital conversion module 116, improve the repeatability and the measuring accuracy of system.
To the measuring-signal and the described voltage excitation signals that obtain is that reference signal is done multiplication demodulation: voltage excitation signals through described measurement module 110 backs just phase places change and signal frequency is constant, after measuring-signal and reference signal are done multiplying by analog multiplier 114, the signal that obtains can be divided into two parts, a part is that frequency is the AC signal of two times of input signals, and another part is a direct current signal; This signal filters high frequency ac signal by low-pass filter 115 again, can obtain the direct current signal after the demodulation.Detailed process is as follows:
Measuring-signal:
Reference signal: V
r(t)=sin (ω t) is (1-2)
Restituted signal: (1-3)
Signal after the demodulation through becoming digital signal after 12 high speed analog-to-digital conversion, is transferred to host computer by described data transmission and control module 104 by described analog-to-digital conversion module 116 again.After host computer procedure processes data, send out the adjustment of digital to analog converter 112 according to the feature of data and instruct, change the digital quantity of digital to analog converter 112 and then change its equivalent resistance, with the impedance of coupling object under test 109 to described control module 107; If coupling is finished, host computer procedure carries out computing, processing to data, and the determinand resistance value information that obtains is presented on the interface.
It is right to utilize a plurality of described measuring sondes 201 to form multi-group electrodes during monitoring, electrode pair can be attached to plant haulm both sides, place soil or be connected on the two ends of standard component; By the gating of data transmission and control module 107 control channel selector switch, measure the impedance value of a plurality of passages respectively, to reach simultaneously the purpose of measuring, contrasting mutually.
More than to the description of the present invention and embodiment thereof, be not limited thereto, only be one of embodiments of the present invention shown in the accompanying drawing.Under the situation that does not break away from the invention aim,, all belong to protection domain of the present invention without creatively designing and similar structure of this technical scheme or embodiment.
Claims (9)
1, the present invention relates to a kind of multichannel electrical impedance type plant water content monitoring system, comprise hardware circuit, measuring sonde 201 and PC part 101; It is characterized in that described hardware circuit comprises USB supply module 103, data transmission and control module 107, driving source generation module 108, metering circuit module 110, multiplication demodulation and low-pass filtering module 113 and analog-to-digital conversion module 116; USB supply module 103 is connected the back and powers to hardware circuit with PC 101, data transmission and control module 107 realize control of passage gating switch and data transmission, the impedance measurement module adopts direct frequency synthesis chip to produce the sine wave of frequency adjustable as driving source, self-balancing bridge circuit through operational amplifier and feedback resistance formation, separate the mediation low-pass filtering by analogue multiplication, finally after analog to digital conversion, data processing, obtain resistance value; Described measuring sonde 201 adopts single-core shielding line and pellet electrode; Described PC part 101 is the control program interface, realizes the control of hardware circuit and the processing and the demonstration of measurement data.
2, according to the described a kind of multichannel electrical impedance type plant water content monitoring system of claim 1, it is characterized in that described hardware circuit part comprises USB supply module 103, data transmission and control module 107, driving source generation module 108, measurement module 110, multiplication demodulation and low-pass filtering module 113 and analog-to-digital conversion module 116.Described USB supply module 103 links to each other with PC 101 by usb data line 102, utilize that data line provides+5V voltage and through voltage transitions chip 105 and 106 obtain respectively+3.3V powers to hardware circuit with ± 15V voltage.
3, according to the described a kind of multichannel electrical impedance type plant water content monitoring system of claim 1, it is characterized in that described data transmission and control module 107, adopt the control core of the EZ-USB FX2 series monolithic of Cypress company production as system, realize the switching gate of control survey passage, control the adjustable sine wave of described driving source generation module 108 output frequencies, for providing the digital quantity input as the digital to analog converter 112 of equivalent feedback resistance in the described measurement module 110, and the digital data that obtains in the described analog-to-digital conversion module 116 is transferred to PC 101 by usb data line 102 handles.
4, according to the described a kind of multichannel electrical impedance type plant water content monitoring system of claim 1, it is characterized in that described driving source generation module 108 adopts direct frequency synthesis chip, this chip mainly partly is made of Direct Digital synthesis system able to programme, high-performance analog to digital converter, realizes the frequency synthesis of digital programming Control.Be written into mode by the control word serial and produce complementary two-way current output signal, again through the current/voltage-converted circuit, adopting the form of difference is excitation and the reference signal of voltage signal as measuring system with two-way complementary current conversion of signals.
5, according to the described a kind of multichannel electrical impedance type plant water content monitoring system of claim 1, it is characterized in that described measurement module 110 is operational amplifier 111 and the self-balancing bridge circuit that constitutes as the digital to analog converter 112 of feedback resistance, the backfeed loop that digital to analog converter 112 is connected on self-balancing bridge can equivalence be feedback resistance, the equivalence resistance is controlled by the digital quantity of described data transmission and control module 107 inputs, can in the scope of 10k Ω to 3M Ω, regulate, and have good linearty.Change the gain of measurement module 110 by regulating the feedback resistance, and then expand the dynamic range of described analog-to-digital conversion module 116.
6, according to the described a kind of multichannel electrical impedance type plant water content monitoring system of claim 1, it is characterized in that described multiplication demodulation module 113 is made up of analog multiplier 114 and low-pass filter 115, the voltage excitation signals that described excitation generation module 108 produces is as the reference signal, signal behind the described measurement module 110 of process is as measuring-signal, this two paths of signals is the input of analog multiplier 114, and the output of analog multiplier 114 enters described analog-to-digital conversion module 116 behind low-pass filter 115.
7, according to the described a kind of multichannel electrical impedance type plant water content monitoring system of claim 1, it is characterized in that described analog-to-digital conversion module 116 is 12 high-speed AD converters, is the simulating signal that measures that 12 bit digital quantity are imported described data transmission module 107 into and data are sent to host computer and handle with higher rate conversion.
8, according to the described a kind of multichannel electrical impedance type plant water content monitoring system of claim 1, it is characterized in that described measuring sonde 201 comprises shielding line and electrode, shielding line can reduce the interference of extraneous spurious signal, potential electrode be to can non-invasively placing different parts of plant or the same area of different plants, and the electrical impedance of the same area by each position of plant or different plants changes the water percentage that reflects plant and changes and health status.
9,, it is characterized in that described PC part 101 is pc control procedure and interface, can write realization with Visual Basic, Visual C, Labview etc. according to the described a kind of multichannel electrical impedance type plant water content monitoring system of claim 1.Pc control procedure is at first controlled the sine voltage signal that described voltage drive module 108 produces required frequency, data that produce according to the described analog-to-digital conversion module that receives 116 again, regulate the equivalent resistance of the digital to analog converter 12 in the described measurement module 110, make it and be complementary by the electrical impedance of measuring plants to obtain the high-acruracy survey result, at last host computer realize measurement result storage, handle and demonstration.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010149077A1 (en) * | 2009-06-25 | 2010-12-29 | 中兴通讯股份有限公司 | Method for implementing electromagnetic anti-interference filter impedance match and measuring system thereof |
| CN102539921A (en) * | 2012-01-04 | 2012-07-04 | 中国农业大学 | Device and method for measuring living body electric conductivity of plant leaf |
| CN103592343A (en) * | 2013-11-25 | 2014-02-19 | 江苏大学 | Method for measuring tensity of plant leaf |
| CN103645355A (en) * | 2013-12-30 | 2014-03-19 | 江苏大学 | Sensor for measuring electrical parameters of plant leaves |
| CN103713021A (en) * | 2014-01-06 | 2014-04-09 | 长春汽车工业高等专科学校 | Detecting method and device with impedance type water content sensor |
| CN109187649A (en) * | 2018-08-14 | 2019-01-11 | 天津大学 | Moisture content and salinity measuring device based on the anti-sensor of plug-in resistance type |
| CN114062448A (en) * | 2022-01-17 | 2022-02-18 | 北京市农林科学院智能装备技术研究中心 | Capacitance collection device and method for predicting water content of straw |
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2009
- 2009-10-10 CN CN200910093917A patent/CN101666768A/en active Pending
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010149077A1 (en) * | 2009-06-25 | 2010-12-29 | 中兴通讯股份有限公司 | Method for implementing electromagnetic anti-interference filter impedance match and measuring system thereof |
| US9897639B2 (en) | 2009-06-25 | 2018-02-20 | Zte Corporation | Method for implementing electromagnetic anti-interference filter impedance match and measuring system thereof |
| CN102539921A (en) * | 2012-01-04 | 2012-07-04 | 中国农业大学 | Device and method for measuring living body electric conductivity of plant leaf |
| CN103592343A (en) * | 2013-11-25 | 2014-02-19 | 江苏大学 | Method for measuring tensity of plant leaf |
| CN103592343B (en) * | 2013-11-25 | 2015-07-29 | 江苏大学 | A kind of method measuring plant leaf blade tensity |
| CN103645355A (en) * | 2013-12-30 | 2014-03-19 | 江苏大学 | Sensor for measuring electrical parameters of plant leaves |
| CN103713021A (en) * | 2014-01-06 | 2014-04-09 | 长春汽车工业高等专科学校 | Detecting method and device with impedance type water content sensor |
| CN103713021B (en) * | 2014-01-06 | 2016-02-03 | 长春汽车工业高等专科学校 | Impedance type moisture sensor detection method and pick-up unit |
| CN109187649A (en) * | 2018-08-14 | 2019-01-11 | 天津大学 | Moisture content and salinity measuring device based on the anti-sensor of plug-in resistance type |
| CN109187649B (en) * | 2018-08-14 | 2020-11-27 | 天津大学 | Water content and mineralization measuring device based on plug-in electrical impedance sensor |
| CN114062448A (en) * | 2022-01-17 | 2022-02-18 | 北京市农林科学院智能装备技术研究中心 | Capacitance collection device and method for predicting water content of straw |
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Application publication date: 20100310 |