CN109916968B - Accurate measurement method and device of capacitance type grain moisture sensor - Google Patents
Accurate measurement method and device of capacitance type grain moisture sensor Download PDFInfo
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Abstract
The invention discloses an accurate measurement method and equipment of a capacitance type grain moisture sensor, which comprises the following steps: a: supplying power to the sensor and the singlechip; b: an oscillation circuit output signal; c: and calculating to obtain a moisture value. The precise calibration method comprises the following steps: s1: initial measurement of zero position; s2: temperature drift calibration; s3: calibrating consistency; s4: and (5) calibrating grain parameters. The sensor comprises a shell, positive and negative electrodes and a detection circuit board, wherein the capacitance detection end point of the detection circuit board is connected with the positive and negative electrodes. The invention adopts the accurate calibration method, so that the uniform algorithm calibration can be carried out aiming at diversified sampling media, and the independent power supply is realized by adopting the power supply circuit with physical isolation, so that all interference sources can be avoided in the detection process, and the single-bus communication scheme is adopted, so that the distributed layout requirement of the grain depot can be conveniently solved.
Description
Technical Field
The invention relates to the technical field of moisture detection, in particular to an accurate measurement method and equipment of a capacitive grain moisture sensor.
Background
At present, most means for testing moisture in the process of grain storage and drying are still manual sampling inspection, the process is complex and the efficiency is low. The Chinese patent application with publication number CN200810055014.8 discloses a digital sensing device for on-line measurement of grain temperature and moisture in grain depot, which adopts a capacitance method to detect grain capacitance and correct the influence of temperature on sensing, and adopts a metal sheet as an electrode; according to finite element analysis, electromagnetic interference has great influence on the sensor, and stable and accurate sensor data information is difficult to obtain.
Chinese patent application publication No. CN201610331177.9 discloses a "method for calculating moisture of a capacitive moisture sensor assembly" which uses a binary function to calibrate the measured moisture, and the method cannot completely satisfy all test situations because the sensor is used for different measuring media, such as rice, wheat, corn, and the like, during the measurement process.
Therefore, in the sensor acquisition process, how to obtain effective sampling data and perform unified algorithm calibration for diversified sampling media is a problem which needs to be considered, and therefore, the accurate measurement method and the accurate measurement equipment for the capacitive grain moisture sensor are provided.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: how to realize the accurate measurement of the grain moisture provides an accurate measurement method of a capacitance type grain moisture sensor.
The invention solves the technical problems through the following technical scheme, and the invention comprises the following steps:
an accurate calibration method of a capacitance type grain moisture sensor comprises the following steps:
s1: initial measurement of zero position
Measuring the dielectric parameter output and the temperature of the sensor in an air medium at normal temperature;
s2: temperature drift calibration
Measuring the dielectric parameter output and the temperature of the sensor in an air medium with the temperature range of 0-40 ℃;
s3: consistency calibration
Measuring the dielectric parameter output and temperature of the sensor in different dielectric constant media,
and by the formula:
performing a calculation in whichDielectric parameterFor dielectric parameters of the object to be measured, F is the output frequency, k, measured by the sensor1,k2,k3Obtaining a relation coefficient of the dielectric parameter and the output frequency by measuring the dielectric parameter and the output frequency F; n is1,n2The calibration parameters are obtained through a calibration formula;
s4: grain parameter calibration
By the formula:
MC＝Sεdielectric parameter 2+QεDielectric parameter+T
Wherein MC is the moisture value of the analyte,. epsilonDielectric parameterAnd the dielectric parameters measured for the measured object are obtained, and S, Q and T are the calibration coefficients of the moisture to be obtained.
A method for accurately measuring a capacitance type grain moisture sensor comprises the following steps:
a: power supply for sensor and single chip
The detection power supply of the sensor, the single chip microcomputer and a working circuit thereof is provided through an external charge pump, and when the charge pump is fully charged, the single chip microcomputer cuts off the external power supply;
b: output signal of oscillating circuit
The oscillation circuit outputs signal frequency for the singlechip to read;
c: calculating to obtain the moisture value
The single chip microcomputer reads the frequency value of the output signal of the oscillating circuit at regular time, calculates the moisture value according to the calibration parameter of the precise calibration method as claimed in claim 1, and finally communicates through a single bus.
An accurate measurement device of a capacitance type grain moisture sensor comprises a singlechip and a sensor, wherein the sensor comprises a shell, a positive electrode, a negative electrode and a detection circuit board, the capacitance detection end points of the detection circuit board are respectively connected with the positive electrode and the negative electrode through leads, the positive electrode and the negative electrode are all circular metal shells, the positive electrode, the negative electrode and the detection circuit board are all positioned in the shell, the detection circuit board is fixedly arranged on the inner sides of the positive electrode and the negative electrode, the positive electrode is fixed at the outer middle position of the detection circuit board, the number of the negative electrodes is two, the two negative electrodes are respectively fixed at the upper and lower outer end positions of the detection circuit board, the detection signal of the detection circuit board is communicated with the single chip microcomputer through a single bus, and the distributed layout requirement of the grain depot can be conveniently met by adopting a single bus communication scheme.
Preferably, the upper end of detection circuitry board is provided with the oscillating circuit who is used for the output signal frequency to supply the singlechip to read, oscillating circuit includes oscillator U1E, resistance R1, oscillating resistance R2 and the electric capacity C that awaits measuring, oscillator U1E's 1 foot is connected oscillating resistance R2's 1 foot, is connected to the positive terminal of electric capacity C that awaits measuring simultaneously, internal power supply ground pin is connected to oscillator U1E's 2 feet, oscillator U1E's 3 feet connecting resistance R1's 2 feet, oscillator U1E's 4 feet are connected and are detected the inside power supply VCC foot of circuitry board, oscillator U1E's 5 feet are connected oscillating resistance R2's 2 feet.
Preferably, sensor cables which are vertically arranged are installed in a distributed mode in the grain depot, each sensor cable comprises a cable, a bus connector and at least two sensor nodes, each sensor node is provided with one sensor, the sensor nodes are connected through the cables, and the bus connectors are installed at the upper ends of the cables.
Preferably, a gateway is fixedly installed at the upper end of one side of the grain depot, the sensor cable is connected with the gateway, and the connection mode is single-bus connection.
Compared with the prior art, the invention has the following advantages: according to the accurate measurement method of the capacitance type grain moisture sensor, due to the adoption of an accurate calibration method, unified algorithm calibration can be carried out on diversified sampling media, and the power supply circuit with physical isolation is adopted to realize independent power supply, so that all interference sources can be avoided in the detection process, and the single-bus communication scheme is adopted, so that the distributed layout requirement of a grain depot can be conveniently met.
Drawings
FIG. 1 is a general architectural diagram of the present invention;
FIG. 2 is a schematic diagram of the construction of the sensor cable of the present invention;
FIG. 3 is a schematic diagram of the construction of the sensor of the present invention;
FIG. 4 is a schematic block diagram of the workflow of the present invention;
FIG. 5 is a schematic diagram of the operating circuit of the single chip microcomputer of the present invention;
FIG. 6 is a schematic diagram of a self-powered charging and discharging circuit of the present invention;
fig. 7 is a schematic diagram of the oscillator circuit of the present invention.
In the figure: 1. a grain depot; 2. a sensor cable; 21. a sensor node; 22. a bus connector; 23. a cable; 3. a gateway; 4. a sensor; 41. a negative electrode; 42. a positive electrode; 43. detecting the circuit board; 44. a housing.
Detailed Description
The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
As shown in fig. 1 to 7, the present embodiment provides a technical solution: a method for accurately measuring a capacitance type grain moisture sensor comprises the following steps:
a: power supply for sensor and single chip
The capacitor C2 is used as a charge pump to provide detection power supply for the sensor, the single chip microcomputer and a working circuit thereof, and when the capacitor C2 is fully charged, the single chip microcomputer disconnects external power supply through IO2 and IO3 ports;
b: output signal of oscillating circuit
The oscillation circuit outputs signal frequency for the singlechip to read;
c: calculating to obtain the moisture value
The single chip microcomputer reads the frequency value of the output signal of the oscillating circuit at regular time, calculates the moisture value according to the calibration parameters of the accurate calibration method, and finally carries out communication through a single bus.
The precise calibration method in the step C comprises the following steps:
s1: initial measurement of zero position
Measuring the dielectric parameter output and temperature of the sensor in an air medium at 25 ℃;
s2: temperature drift calibration
Measuring the dielectric parameter output and the temperature of the sensor in an air medium with the temperature range of 0-40 ℃;
s3: consistency calibration
Measuring the dielectric parameter output and the temperature of the sensor in different dielectric constant media; and by the formula:
performing a calculation in whichDielectric parameterFor dielectric parameters of the object to be measured, F is the output frequency, k, measured by the sensor1,k2,k3Obtaining a relation coefficient of the dielectric parameter and the output frequency by measuring the dielectric parameter and the output frequency F; n is1,n2The calibration parameters are obtained through a calibration formula;
s4: grain parameter calibration
By the formula:
MC＝Sεdielectric parameter 2+QεDielectric parameter+T
Wherein MC is the moisture value of the analyte,. epsilonDielectric parameterAnd the dielectric parameters measured for the measured object are obtained, and S, Q and T are the calibration coefficients of the moisture to be obtained.
The embodiment also provides an accurate measurement device of a capacitance type grain moisture sensor, which comprises a single chip microcomputer and a sensor 4, wherein the sensor 4 comprises a shell 44, a positive electrode 42, a negative electrode 41 and a detection circuit board 43, the positive electrode 42 is a copper ring with an inner diameter of 12mm, an outer diameter of 13mm and a length of 3mm, the negative electrode 41 is a copper ring with an inner diameter of 12mm, an outer diameter of 13mm and a length of 1mm, capacitance detection end points of the detection circuit board 43 are respectively connected with the positive electrode 42 and the negative electrode 41 through leads, the positive electrode 42, the negative electrode 41 and the detection circuit board 43 are all positioned in the shell 44, the detection circuit board 43 is fixedly arranged on the inner sides of the positive electrode 42 and the negative electrode 41, the positive electrode 42 is fixed at the middle position outside the detection circuit board 43, the number of the negative electrodes 41 is two, the two negative electrodes 41 are respectively fixed at the upper and lower end positions outside the detection circuit board 43, detection signals of the detection circuit board 43 are communicated with the single chip microcomputer through a single bus, by adopting a single bus communication scheme, the distributed layout requirement of the grain depot can be conveniently met.
Further, vertically arranged sensor cables 2 are installed in the grain depot 1 in a distributed mode, each sensor cable 2 comprises a cable 23, a bus connector 22 and at least two sensor nodes 21, each sensor node 21 is provided with one sensor 4, the sensor nodes 21 are connected through the cables 23, and the bus connector 22 is installed at the upper end of the cable 23.
Furthermore, the single chip microcomputer is used for charging, detecting, calculating and communicating through the peripheral control sensor 4, and the detection related circuits comprise a single chip microcomputer working circuit, a self-powered charging and discharging circuit and an oscillating circuit.
The single-chip microcomputer working circuit comprises a single-chip microcomputer U1A, a resistor R3 and a capacitor C1, the self-powered charging and discharging circuit comprises a controllable switch S1, a controllable switch S2 and a capacitor C2, and the oscillating circuit comprises an oscillator U1E, a resistor R1, an oscillating resistor R2 and a capacitor C to be tested.
A pin 1 of a singlechip U1A is connected with a pin 1 of a capacitor C1, a pin 2 of a singlechip U1A is connected with a pin 5 of an oscillator U1E, a pin 3 of the singlechip U1A is connected with a pin 1 of a resistor R1, a pin 4 of a singlechip U1A is connected with a pin 3 of a controllable switch S2, a pin 5 of the singlechip U1A is connected with a pin 3 of a controllable switch S1, a pin 7 of the singlechip U1A is connected with a single bus through ONEWIRE, and a pin 16 of the singlechip U1A is connected with a pin 2 of the resistor R3;
a pin 2 of the capacitor C1 is connected with a power supply grounding pin in the detection circuit board, a pin 1 of the resistor R3 is connected with a power supply VCC pin in the detection circuit board, and a pin 2 of the resistor R1 is connected with a pin 3 of the oscillator U1E;
a pin 1 of the oscillator U1E is connected with a pin 1 of the oscillating resistor R2 and is simultaneously connected with the positive terminal of the capacitor C to be tested, a pin 2 is connected with the internal power supply grounding pin, a pin 3 is connected with a pin 2 of the R1, a pin 4 is connected with the internal power supply VCC pin of the detection circuit board, and a pin 5 is connected with a pin 2 of the oscillating resistor R2;
the negative end of the capacitor C to be detected is connected with the internal grounding pin of the detection circuit board.
Further, after the electric quantity of the charge pump C2 is too low, the controllable switch S2 and the controllable switch S1 can be controlled and triggered to be closed to an external power supply and an external ground through IO2 and IO3 of the single chip microcomputer, the controllable switch S2 and the controllable switch S1 can be triggered to be closed through IO2 and IO3 low levels, the charge of the charge pump C2 by the external power supply is achieved, and therefore automatic charging and discharging and timing reading of grain moisture parameters are achieved.
In summary, according to the accurate measurement method of the capacitive grain moisture sensor of the embodiment, since the accurate calibration method is adopted, uniform algorithm calibration can be performed for diversified sampling media, and the power supply circuit with physical isolation is adopted to realize independent power supply, so that all interference sources can be avoided in the detection process, and a single-bus communication scheme is adopted, so that the distributed layout requirement of a grain depot can be conveniently met.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (6)
1. The accurate calibration method of the capacitive grain moisture sensor is characterized by comprising the following steps of:
s1: initial measurement of zero position
Measuring the dielectric parameter output and the temperature of the sensor in an air medium at normal temperature;
s2: temperature drift calibration
Measuring the dielectric parameter output and the temperature of the sensor in an air medium with the temperature range of 0-40 ℃;
s3: consistency calibration
Measuring the dielectric parameter output and temperature of the sensor in different dielectric parameter media,
and by the formula:
performing a calculation in whichDielectric parameterFor dielectric parameters of the object to be measured, F is the output frequency, k, measured by the sensor1,k2,k3Obtaining a relation coefficient of the dielectric parameter and the output frequency by measuring the dielectric parameter and the output frequency F; n is1,n2The calibration parameters are obtained through a calibration formula;
s4: grain parameter calibration
By the formula:
MC＝Sεdielectric parameter 2+QεDielectric parameter+T
Wherein MC is the moisture value of the analyte,. epsilonDielectric parameterAnd the dielectric parameters measured for the measured object are obtained, and S, Q and T are the calibration coefficients of the moisture to be obtained.
2. The accurate measurement method of the capacitance type grain moisture sensor is characterized by comprising the following steps:
a: power supply for sensor and single chip
The detection power supply of the sensor, the single chip microcomputer and a working circuit thereof is provided through an external charge pump, and when the charge pump is fully charged, the single chip microcomputer cuts off the external power supply;
b: output signal of oscillating circuit
The oscillation circuit outputs signal frequency for the singlechip to read;
c: calculating to obtain the moisture value
The single chip microcomputer reads the frequency value of the output signal of the oscillating circuit at regular time, calculates the moisture value according to the calibration parameter of the precise calibration method as claimed in claim 1, and finally communicates through a single bus.
3. The utility model provides an accurate measuring equipment of capacitanc grain moisture sensor which characterized in that: the measurement method of claim 2 is adopted to measure the moisture content of the grain, and comprises a single chip microcomputer and a sensor, wherein the sensor comprises a shell, a positive electrode, a negative electrode and a detection circuit board, capacitance detection end points of the detection circuit board are respectively connected with the positive electrode and the negative electrode through leads, the positive electrode and the negative electrode are all circular metal shells, the positive electrode, the negative electrode and the detection circuit board are all positioned in the shell, the detection circuit board is fixedly arranged on the inner sides of the positive electrode and the negative electrode, the positive electrode is fixed at the middle position outside the detection circuit board, the number of the negative electrodes is two, the two negative electrodes are respectively fixed at the upper end position and the lower end position outside the detection circuit board, and detection signals of the detection circuit board are communicated with the single chip microcomputer through a single bus.
4. The precise measurement device of the capacitive grain moisture sensor according to claim 3, wherein: the upper end of detection circuitry board is provided with the oscillating circuit who is used for the output signal frequency to supply the singlechip to read, oscillating circuit includes oscillator U1E, resistance R1, oscillating resistance R2 and the electric capacity C that awaits measuring, oscillator U1E's 1 foot is connected oscillating resistance R2's 1 foot, be connected to the positive terminal of electric capacity C that awaits measuring simultaneously, inside power supply ground connection foot is connected to oscillator U1E's 2 feet, oscillator U1E's 3 feet connecting resistance R1's 2 feet, oscillator U1E's 4 feet are connected the inside power supply VCC foot of detection circuitry board, oscillator U1E's 5 feet are connected oscillating resistance R2's 2 feet.
5. The precise measurement device of the capacitive grain moisture sensor according to claim 3, wherein: the sensor cable that sets up perpendicularly is installed to grain depot inside distributing type, the sensor cable includes cable, bus connector and two at least sensor nodes, every the sensor node has a sensor, is connected through the cable between a plurality of sensor nodes, the upper end at the cable is installed to the bus connector.
6. The precise measurement device of the capacitive grain moisture sensor according to claim 5, wherein: the sensor cable is connected with the gateway in a single-bus connection mode.
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| CN110426425A (en) * | 2019-08-06 | 2019-11-08 | 仕达科技(广州)有限公司 | Moisture detecting method, device, electronic equipment and computer-readable medium |
| CN110793575A (en) * | 2019-11-23 | 2020-02-14 | 浙江托普云农科技股份有限公司 | Farmland information monitoring device |
| CN111474335A (en) * | 2020-03-10 | 2020-07-31 | 安徽科杰粮保仓储设备有限公司 | Grain mycotoxin on-line detection method and device based on immunosensor |
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