CN104316243A - Raindrop impact kinetic energy testing system based on multipoint PVDF piezoelectric thin-film sensor - Google Patents
Raindrop impact kinetic energy testing system based on multipoint PVDF piezoelectric thin-film sensor Download PDFInfo
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- CN104316243A CN104316243A CN201410555279.XA CN201410555279A CN104316243A CN 104316243 A CN104316243 A CN 104316243A CN 201410555279 A CN201410555279 A CN 201410555279A CN 104316243 A CN104316243 A CN 104316243A
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Abstract
The invention discloses a raindrop impact kinetic energy testing system based on a multipoint PVDF piezoelectric thin-film sensor. The testing system is composed of a PVDF piezoelectric thin film, an insulating thin-film substrate, a copper grid line, a lead, a signal amplifying circuit and a signal acquisition circuit. The piezoelectric thin film is located on the upper part of the insulating thin-film substrate; the copper grid line is photoetched on the insulating thin-film substrate; the lead is connected to the upper and lower surfaces of the grid line, and the upper surface serves as a signal leading-out end, while the lower surface is grounded; the signal leading-out end is connected with the input end of the amplifying circuit; the output end of the amplifying circuit is connected with the signal acquisition circuit. The raindrop impact kinetic energy testing system which is quick and accurate, convenient to operate and simple in structure is designed by utilizing a novel high polymer material PVDF piezoelectric thin film; the raindrop impact kinetic energy testing system is capable of obtaining the raindrop impact kinetic energy quickly and conveniently, capable of realizing multipoint real-time measurement and the raindrop impact strength testing within a certain range, and also capable of eliminating single-point test errors; as a result, the impact force of a mobile spray irrigation apparatus in the agricultural field can be possibly tested.
Description
Technical field
The invention belongs to raindrop impact kinetic energy proving installation, in particular to a kind of raindrop impact kinetic energy test macro based on multiple spot PVDF piezoelectric film sensor, be applicable to the raindrop of measurement sprinkling irrigation equipment generation to ground, plant surface and inner hitting power and strike kinetic energy.
Background technology
The major impetus that strike effect is bare soil erosion is spattered in hitting of raindrop, rain insensitive device kinetic energy is to calcium, magnesium, sodium calcium and sodium magnesium permeability in soil have a significant impact, when rain insensitive device kinetic energy rises, soil compaction degree is corresponding increase also, and Raindrop hitting power directly can affect the seed output and quality of crops to the effect of tender leaf, therefore Raindrop hitting power and strike kinetic energy are one of important factor in order selecting sprinkling irrigation equipment, are also one of Precision Irrigation important parameters.
Existing raindrop impact force measuring sensors mainly contains mathematical model method, High Speed Photography, laser method, acoustic sensor mensuration and strainometer mensuration.But said method all also exists limitation, at measurement sprinkling irrigation water droplet to crop inside, the impulsive force size aspect of top and surrounding, measurement aspect especially is in real time difficult to realize.Mathematical model method uses in conjunction with High Speed Photography and laser method usually, is mainly used in the speed and the size that measure water droplet.High Speed Photography widely uses in an experiment, in order to analyze the effect of a branch of water droplet stream, but this method measure multi beam coexist the situation of water droplet stream time helpless.Acoustic sensor is excessive, and strainometer needs electric power and other elements, such as resistance, amplifier and wave filter, which limits usable range and the service time of sensor.External more typical Raindrop sensor is at present the sensor automatically controlling vehicle wiper.Domesticly start late, technology is also immature, and Raindrop sensor application is agriculturally less.
Novel high polymer material PVDF piezoelectric membrane has very excellent performance, and its variable force response sensitivity is than quartz-crystal height 10 times, and piezoelectric voltage output constant g=174 is the highest in all piezoelectrics, its Qm is low, damping is little, density is low, there is broadband character, the frequency characteristic of pulse signal can be met, due to the flexibility of PVdF film and the resonance frequency of thickness direction stretching vibration very high, it has flat frequency to respond (responding range is 0.1-100MHz) in wide range, the frequency of single raindrop impact kinetic energy is very low, be about 0.5 ~ 4Hz, therefore, theoretically, PVDF piezoelectric membrane is the ideal material of the test realizing raindrop impact kinetic energy, but the application of piezoelectric membrane in agriculture field is little, therefore in agricultural based on the Raindrop hitting power of PVDF piezoelectric membrane and hit can design of measuring system exploitation be very necessary.
Summary of the invention
The defect existed for current existing Raindrop sensor or deficiency, the object of the invention is to, a kind of humidity is provided, high output signal can be produced to very little impulsive force, noise signal is little, and can realize the raindrop impact kinetic energy test macro based on multiple spot PVDF piezoelectric film sensor that multiple spot measures in real time.
In order to realize above-mentioned task, the present invention takes following technical solution:
A kind of raindrop impact kinetic energy test macro based on multiple spot PVDF piezoelectric film sensor, it is characterized in that by PVDF piezoelectric membrane (1), insulation film substrate (2), copper grid line (3), lead-in wire (4), signal amplification circuit (5), signal acquisition circuit composition (6); Described PVDF piezoelectric membrane (1) is positioned at insulation film substrate (2) top, cover insulating coating, for measuring the change of shower nozzle shower jet direction Raindrop hitting power, rainfall splash intensity test can be realized in certain limit, and the error that spot measurement brings can be eliminated; The upper copper grid line of photoetching (3) of described insulation film substrate (2), connects lead-in wire (4) by grid line (3) upper and lower surface, upper surface as signal exit, lower surface ground connection; Described copper grid line (3) signal exit (4) is connected with signal amplification circuit (5), realizes the conversion of the quantity of electric charge to voltage and the amplification of voltage signal; Described signal amplification circuit (5) is connected with signal acquisition circuit (6), realizes the filtering of voltage signal, analog to digital conversion, storage and computing.
Each measurement point PVDF piezoelectric membrane (1) area described is 1.5mm*1.5mm, thickness is 35 μm, 3 measuring points are set along jet direction, 4, each position measurement point totally 12 measuring points, for measuring the change of shower nozzle shower jet direction Raindrop hitting power; Described each measurement point spacing is 1mm, can to realize in certain limit rainfall splash intensity test, and can eliminate the error that spot measurement brings.
Described signal amplification circuit (5) is made up of two-stage calculation amplifying circuit, the first order is the voltage follower connected into by a high input impedance amplifier, the charge signal that described multiple spot PVDF piezoelectric film sensor exports is converted into maximal value about ± voltage of 160mV, above-mentioned magnitude of voltage is amplified to computing machine and carries out the voltage range (± 5V) that data acquisition is comparatively suitable for by second level amplifying circuit.
Being made up of filtering circuit, analog-to-digital conversion circuit, storage circuit, power circuit and single-chip microcomputer of described signal acquisition circuit (6), realize the filtering of signal, analog to digital conversion, storage and computing.
The multipoint mode PVDF piezoelectric film sensor that the present invention adopts is a kind of passive sensor, humidity, noise signal is little, and can measure small voltage signal, be convenient to be arranged on field and plant surface, accurately can obtain the relation of impulsive force, impact kinetic energy and installation site.Signal amplification circuit receives the analog pulse signal that piezoelectric membrane exports, charge signal is enlarged into computing machine and carries out the voltage range that data acquisition is comparatively suitable for, signal acquisition circuit is by certain signal transacting, data conversion, the signal collected piezoelectric membrane processes, store and be transferred to PC, do the mutual communication that such signal transacting can realize between analog network and digital network, complete exchanges data, make data remote transmission, Commissioning Analysis becomes possibility.PC carries out regretional analysis by the data collected signal acquisition circuit, obtains the computation model of raindrop impact kinetic energy and output voltage, thus can obtain Raindrop hitting power quickly and easily and hit kinetic energy.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention.
Mark in figure represents respectively: 1.PVDF piezoelectric membrane, 2. insulation film substrate, 3. copper grid line, 4. lead-in wire, 5. signal amplification circuit, 6. signal acquisition circuit.
Fig. 2 is multipoint mode PVDF piezoelectric film sensor structural representation of the present invention, and Fig. 2 (a) is the vertical view of structural representation, and Fig. 2 (b) is side view.
Mark 1.PVDF piezoelectric membrane in figure, 2. insulation film substrate, 3. copper grid line, 4. lead-in wire.
Fig. 3 is signal amplification circuit illustrative view of functional configuration of the present invention.
Fig. 4 is signal acquisition circuit illustrative view of functional configuration of the present invention.
Fig. 5 is single raindrop output voltage waveform;
Fig. 6 is the output voltage waveform after many raindrop act on successively;
Fig. 7 is the output voltage waveform after many raindrop act on simultaneously;
Below in conjunction with drawings and Examples, the present invention is described in further detail.
Embodiment
See Fig. 1, the present embodiment provides a kind of raindrop impact kinetic energy test macro based on multiple spot PVDF piezoelectric film sensor, by PVDF piezoelectric membrane 1, insulation film substrate 2, copper grid line 3, lead-in wire 4, signal amplification circuit 5, signal acquisition circuit 6 forms, piezoelectric membrane 1 is positioned at insulation film substrate 2 top, for measuring the change of shower nozzle shower jet direction Raindrop hitting power, the copper grid line 3 of photoetching in insulation film substrate 2, grid line 3 upper and lower surface is connect lead-in wire 4, upper surface is as signal exit, lower surface ground connection, signal exit 4 is connected with signal amplification circuit 5, realize the conversion of the quantity of electric charge to voltage and the amplification of voltage signal, signal amplification circuit 5 is connected with signal acquisition circuit 6, realize the filtering of voltage signal, analog to digital conversion, store and computing.
See Fig. 2, because the thickness of piezoelectric membrane 1 charge sensitivity and piezoelectric membrane 1, area are closely related, the position of extension line 4 and connected mode can have an impact to the measuring accuracy of piezoelectric membrane 1 equally, therefore, piezoelectric membrane 1 area too conference cause the dynamic corresponding hysteresis phenomenon aggravation of piezoelectric membrane 1.Consider the accuracy requirement of described sensor, installation site, lead-in wire connected mode etc., each measurement point piezoelectric membrane area is 1.5mm*1.5mm, thickness is 35 μm, for measuring the change of shower nozzle shower jet direction Raindrop hitting power, arrange 3 measuring points along jet direction, 4, each position measurement point totally 12 measuring points, described each measurement point spacing is 1mm, rainfall splash intensity test can be realized in certain limit, and the error that spot measurement brings can be eliminated.Consider the position problems of lead-in wire, adopt the method for the copper grid line 3 of photoetching in insulation film substrate 2 to make lead-in wire, grid line 3 upper and lower surface is connect lead-in wire 4, upper surface is as signal exit, and lower surface ground connection, piezoelectric membrane covers insulation layer.
See Fig. 3, described signal amplification circuit 5 is made up of two-stage calculation amplifying circuit, the first order is the voltage follower connected into by a high input impedance amplifier, the charge signal that described multiple spot PVDF piezoelectric film sensor exports is converted into maximal value about ± voltage of 160mV, above-mentioned magnitude of voltage is amplified to computing machine and carries out the voltage range (± 5V) that data acquisition is comparatively suitable for by second level amplifying circuit.
See Fig. 4, being made up of filtering circuit, analog-to-digital conversion circuit, storage circuit, power circuit and single-chip microcomputer of described signal acquisition circuit 6, realize the filtering of signal, analog to digital conversion, storage and computing.
In sum, the raindrop impact kinetic energy test macro based on multiple spot PVDF piezoelectric film sensor that above-described embodiment obtains, by the output voltage that the water droplet impulsive force measuring known quality and known descent altitude produces, the kinetic energy values of water droplet and the linear relationship of piezoelectric membrane output voltage can be determined, thus realize the Quick Measurement of raindrop impact kinetic energy.
Its know-why measured is:
1, measured by piezoelectric membrane 1 and record and often drip output voltage corresponding to raindrop impact kinetic energy, lot of experimental data is added up and regretional analysis, obtaining the relational expression of hitting kinetic energy and output voltage:
y＝kx (1)
Y: sensor voltage exports (V),
X: kinetic energy values (J),
K: constant, can be obtained by regretional analysis.
2, by measuring the diameter and descent altitude that singly drip, can calculate and recording its quality, trying to achieve the theory of often dripping and hit kinetic energy, error analysis is carried out to the actual strike kinetic energy recorded.The computing formula that theoretical water droplet hits kinetic energy is as follows:
In formula: V: water drip rate;
G=9.81 rice/square second
D: drop diameter, mm
ρ
w: water droplet density
ρ
a: atmospheric density
C
d: air resistance coefficient
τ: distance of fall
After the water drip rate V of formula (2) obtains, utilize following formula (3) that water droplet kinetic energy can be tried to achieve:
KE＝0.5×m×v
2 (3)
In formula:
KE: water droplet kinetic energy,
M: water droplet quality
3, to the output voltage pulse analysis that piezoelectric membrane produces
Known through applicant's previous experiments, the strike kinetic energy scope of sprinkling irrigation water droplet is 0.01 × 10
-3~ 1.2 × 10
-3between J, the kinetic energy values that the raindrop impact kinetic energy test macro based on multiple spot PVDF piezoelectric film sensor therefore adopting above-described embodiment to prepare can realize within the scope of this is measured.
(1) singly drip when acting on piezoelectric membrane, the output voltage waveforms of generation as shown in Figure 5.
Setting initial threshold, the output voltage exceeding threshold voltage is designated as effective output, when being applied on piezoelectric membrane when singly dripping, thinks that the maximal value of output voltage is that the voltage that this raindrop impact kinetic energy produces exports, record this voltage, utilize formula can obtain the strike kinetic energy of these raindrop.
(2) many raindrop act on piezoelectric membrane successively, and when action time, interval was longer, the output voltage waveforms of generation as shown in Figure 5.
The output voltage exceeding threshold voltage is designated as effective output, as shown in Figure 5, think and have 4 raindrop to act on piezoelectric membrane, and its action time is not overlapping, the output voltage values of record useful effect raindrop, can obtain the strike kinetic energy values that many act on the raindrop on piezoelectric membrane successively.
Many raindrop act on piezoelectric membrane simultaneously, or effect is very short for interval time, and the oscillogram during output voltage waveforms generation aliasing of generation as shown in Figure 6.
When many raindrop act on piezoelectric membrane simultaneously, output voltage is temporally sampled, calculate the average voltage level that in a period of time, piezoelectric membrane exports, can be calculated the average strike kinetic energy of during this period of time many raindrop.Be applicable to measure in actual production the hitting power on sprinkling irrigation equipment and ground overall to plant leaf blade, plant and hit kinetic energy.
Claims (4)
1. the raindrop impact kinetic energy test macro based on multiple spot PVDF piezoelectric film sensor, it is characterized in that by PVDF piezoelectric membrane (1), insulation film substrate (2), copper grid line (3), lead-in wire (4), signal amplification circuit (5), signal acquisition circuit (6) forms; Described piezoelectric membrane (1) is positioned at insulation film substrate (2) top, for measuring the change of shower nozzle shower jet direction Raindrop hitting power, along jet direction, 3 measuring points are set, 4, each position measurement point totally 12 measuring points, rainfall splash intensity test can be realized in certain limit, and the error that spot measurement brings can be eliminated; The upper copper grid line of photoetching (3) of described insulation film substrate (2), and make lead-in wire (4), connects lead-in wire (4) by grid line upper and lower surface, upper surface as signal exit, lower surface ground connection; Described each measurement point spacing is 1mm, and piezoelectric membrane (1) is upper covers insulation layer; Described lead-in wire (4) signal output part is connected with signal amplification circuit (5), realizes the conversion of the quantity of electric charge to voltage and the amplification of voltage signal; Described signal amplification circuit (5) is connected with signal acquisition circuit (6), realizes the filtering of voltage signal, analog to digital conversion, storage and computing.
2. as claimed in claim 1 based on the raindrop impact kinetic energy test macro of multiple spot PVDF piezoelectric film sensor, it is characterized in that each described measurement point piezoelectric membrane (1) area is 1.5mm*1.5mm, thickness is 35 μm, and its measurement range is 0.0144 ~ 1.1948 × 10
-3j, can survey drop diameter scope is 1.2mm ~ 4.6mm.
3. as claimed in claim 1 based on the raindrop impact kinetic energy test macro of multiple spot PVDF piezoelectric film sensor, it is characterized in that described signal amplification circuit (5) is made up of two-stage calculation amplifying circuit, the first order is the voltage follower connected into by a high input impedance amplifier, the charge signal that described multiple spot PVDF piezoelectric film sensor exports is converted into maximal value about ± voltage of 160mV, above-mentioned magnitude of voltage is amplified to computing machine and carries out the voltage range (± 5V) that data acquisition is comparatively suitable for by second level amplifying circuit.
4. as claimed in claim 1 based on the raindrop impact kinetic energy test macro of multiple spot PVDF piezoelectric film sensor, it is characterized in that being made up of filtering circuit, analog-to-digital conversion circuit, storage circuit, power circuit and single-chip microcomputer of described signal acquisition circuit (6), realize the filtering of signal, analog to digital conversion, storage and computing.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105486885A (en) * | 2015-12-23 | 2016-04-13 | 云南大学 | High precision karst cave water dripping sensor and collection device |
| CN106706177A (en) * | 2016-11-11 | 2017-05-24 | 浙江大学 | Double-layered crisscross-structure particle collision sensor based on PVDF (Polyvinylidene Fluoride) |
| CN106768569A (en) * | 2017-03-24 | 2017-05-31 | 沈阳建筑大学 | A kind of shock measuring system of array PVDF piezoelectric membranes |
| CN108489547A (en) * | 2018-04-09 | 2018-09-04 | 湖南农业大学 | A kind of raindrop parameter test device |
| CN109211514A (en) * | 2018-10-31 | 2019-01-15 | 大连理工大学 | A kind of rainfall collision force measuring device |
| CN112881646A (en) * | 2021-01-11 | 2021-06-01 | 西北农林科技大学 | Method for measuring flow resistance of slope surface thin layer influenced by raindrops striking |
| CN113405980A (en) * | 2021-07-20 | 2021-09-17 | 北京安赛博技术有限公司 | Method and device for measuring rainfall erosion force |
| CN113791461A (en) * | 2021-09-27 | 2021-12-14 | 中电科技集团重庆声光电有限公司 | Transduction structure of piezoelectric rainfall sensor and installation method thereof |
-
2014
- 2014-09-29 CN CN201410555279.XA patent/CN104316243A/en active Pending
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105486885A (en) * | 2015-12-23 | 2016-04-13 | 云南大学 | High precision karst cave water dripping sensor and collection device |
| CN105486885B (en) * | 2015-12-23 | 2023-06-20 | 云南大学 | High-precision karst cave drip sensor and collecting device thereof |
| CN106706177A (en) * | 2016-11-11 | 2017-05-24 | 浙江大学 | Double-layered crisscross-structure particle collision sensor based on PVDF (Polyvinylidene Fluoride) |
| CN106706177B (en) * | 2016-11-11 | 2019-01-25 | 浙江大学 | A kind of double-layer cross intersection construction particles collision sensor based on PVDF |
| CN106768569A (en) * | 2017-03-24 | 2017-05-31 | 沈阳建筑大学 | A kind of shock measuring system of array PVDF piezoelectric membranes |
| CN108489547A (en) * | 2018-04-09 | 2018-09-04 | 湖南农业大学 | A kind of raindrop parameter test device |
| CN109211514A (en) * | 2018-10-31 | 2019-01-15 | 大连理工大学 | A kind of rainfall collision force measuring device |
| CN109211514B (en) * | 2018-10-31 | 2024-03-08 | 大连理工大学 | Rainfall collision force measuring device |
| CN112881646A (en) * | 2021-01-11 | 2021-06-01 | 西北农林科技大学 | Method for measuring flow resistance of slope surface thin layer influenced by raindrops striking |
| CN113405980A (en) * | 2021-07-20 | 2021-09-17 | 北京安赛博技术有限公司 | Method and device for measuring rainfall erosion force |
| CN113791461A (en) * | 2021-09-27 | 2021-12-14 | 中电科技集团重庆声光电有限公司 | Transduction structure of piezoelectric rainfall sensor and installation method thereof |
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