CN2709978Y - Device for real-time measuring moisure of grain - Google Patents
Device for real-time measuring moisure of grain Download PDFInfo
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- CN2709978Y CN2709978Y CN 200420077708 CN200420077708U CN2709978Y CN 2709978 Y CN2709978 Y CN 2709978Y CN 200420077708 CN200420077708 CN 200420077708 CN 200420077708 U CN200420077708 U CN 200420077708U CN 2709978 Y CN2709978 Y CN 2709978Y
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Abstract
The utility model discloses a device for real-time measuring moisture of grain, comprising a capacitance type sensor used for measuring the capacitance of the grain, a conversion interface integrated circuit used for processing the signal of the capacitance type sensor, and a power circuit. The signal output end of the capacitance type sensor is connected with the measuring end of the conversion interface integrated circuit; an output interface is connected with the output end of the conversion interface integrated circuit, and the output end of the conversion interface integrated circuit can be used for outputting voltage which is in the linearity relationship with the capacitance of the grain output by the signal end of the capacitance type sensor; the input end of the power circuit is connected outwards with the power through a power interface, and the output end is connected with the power end of the conversion interface integrated circuit. The utility model has the advantages of simple circuit, low cost, stable performance, exact measure and consistent output signal magnitude, and has the convenience for subsequent signal processing and display.
Description
Technical field
The utility model relates to a kind of grain moisture measurement mechanism, especially a kind of device that adopts capacitance method to measure grain moisture in real time.
Background technology
The precision agriculture essence of representative information epoch crop production administrative skill thought revolution is based on the agricultural system that information and knowledge are come the precision management complexity, this system at first requires the information acquisition means of application of advanced as far as possible to come fast, in real time, obtain the crop yield of sub-district, farmland lower cost, difference information such as quality, and the various objective datas that influence crop production, from lot of data, extract the information that helps the decision-making of farming management science then, reach the technical economical index of expection at last by measures such as various variable agricultural machines or artificial regulatory management.In the middle of many agricultural land informations, therefore crop yield spatial variability information occupy considerable status owing to be the concentrated expression of the various cultivation management decision-makings in farmland.Because the needs of precision agriculture and the development of global position system, Application and Development the corn mowing machine of output and reaping area measurement system is installed.When measuring output in real time, also measure the water percentage of cereal in real time, so that carry out the evaluation of yield data calibration (being converted to the output of a certain standard aqueous rate) and grain quality.
The method of measuring grain moisture at present mainly contains: electric-resistivity method, Ka Erfeixiufa, equilibrium relative humidity (ERH) method, capacitance method, acoustic method etc.In the above-mentioned various moisture measurement method, higher, the complex structure of most costs, or complicated operation, or be unsuitable for on-line testing, some also is in the development test stage.Compare mutually, the condenser type moisture transducer has advantages such as simple in structure, cheap, easy to operate, firm, is suitable for real-time testing, so use morely.The principle that capacitance method is surveyed cereal moisture percentage is: the electric capacity that the flat capacitor device is presented can be represented by the formula:
In the formula: C-electric capacity; ε
r--the medium relative dielectric constant;
A--pole plate area; The d--polar plate spacing from.
By (1) formula as seen, when the pole plate area A with when constant apart from d, electric capacity is only relevant with the medium relative dielectric constant.The grain specific inductive capacity of bone dry is generally 2～3, and the specific inductive capacity of water can be up to 81.5.The condenser type moisture transducer is a medium with the cereal of certain water percentage, the variation of water percentage can cause the variation of cereal specific inductive capacity, thereby cause the variation of the capacity of condenser of the certain cereal of carrying, the signal that detects electric capacity is handled again, i.e. the value of corresponding water percentage.But for the capacitance type sensor of measuring grain moisture, the equivalent electrical circuit of capacitance type sensor is not only to be pure electric capacity, and should be circuit shown in Figure 1, and wherein, Rp is a shunt loss resistance, and it comprises leakage loss between pole plate and the dielectric loss between pole plate.This part is bigger when low frequency usually, and along with the rising of frequency, capacitive reactance reduces, and its influence also just weakens.Serial resistance Rs comprises the ohmic loss between lead, metal shell and pole plate.This value is normally very little.Inductance L is made up of the inductance of capacitive transducer itself and the inductance of outside lead.The total loss coefficient of the capacitance type sensor ratio of reactive power (active power of actual capacitance with) is
The circular frequency of ω in the formula---electric oscillation.As can be seen, along with the difference of ω, the dielectric loss of cereal is also different.
Usually the resonant circuit of usefulness is surveyed the method for electric capacity, because resonance frequency changes along with electric capacitance change exactly, so the dielectric loss of cereal is inconstant, must bring the systematic error of capacitance measurement like this.The design frequency stabilization circuit utilizes phase-locked loop circuit to measure, and as shown in Figure 2, wherein, the LC voltage controlled oscillator connects the capacitance type sensor that is used to measure cereal electric capacity.When the capacitance variations of tested cereal, the output frequency of voltage controlled oscillator changes, cause changing with the difference on the frequency of crystal oscillator, control the LC voltage controlled oscillator by frequency discriminator output one control voltage again after by low-pass filter, the frequency basically identical of control output frequency and crystal oscillator, so just guaranteed the substantially constant of sensor oscillation frequency, also can detect the size of electric capacity by the voltage swing of control LC voltage controlled oscillator.But this method circuit complexity and device parameters are difficult for selecting, and cost is also higher, is difficult for reaching measurement effect preferably.
The utility model content
Technical problem to be solved in the utility model is, at the deficiencies in the prior art, proposes a kind of grain moisture real-time measurement apparatus, not only can realize real-time measurement, can also guarantee frequency stabilization, and circuit is simple, the measuring accuracy height, and with low cost.
The utility model is realized by the following technical solutions:
A kind of grain moisture real-time measurement apparatus, comprise the capacitance type sensor that is used to measure cereal electric capacity, translation interface integrated circuit, the feed circuit that are used to handle the capacitance type sensor signal, the signal output part of described capacitance type sensor is connected with the measuring junction of translation interface integrated circuit, the output terminal of described translation interface integrated circuit is connected with output interface, the input end of described feed circuit is by the power supply interface external power supply, and output terminal is connected with the power end of translation interface integrated circuit.
Measuring junction at described translation interface integrated circuit is parallel with the electric capacity that the cereal electric capacity that is used for presenting with cereal to be measured constitutes Measurement of capacitor.
Between the output terminal of described translation interface integrated circuit and output interface, be connected with amplifying circuit and current/charge-voltage convertor in turn, the output terminal of translation interface integrated circuit is connected with input end, the reference voltage end of amplifying circuit respectively, the output terminal of amplifying circuit is connected with the input end of current/charge-voltage convertor, and the output terminal of current/charge-voltage convertor is connected with output interface.
Described translation interface integrated circuit is that the model that German AMG Co. produces is the integrated circuit with signal acquisition process, differential voltage output function of CAV424.
Described amplifying circuit is an operational amplifier, and described current/charge-voltage convertor is an integrated circuit.
This measurement mechanism also is provided with temperature-compensation circuit, described temperature-compensation circuit comprises temperature sensor, amplifying circuit, current/charge-voltage convertor, voltage stabilizer, the signal end of described temperature sensor is connected with the input end of amplifying circuit, the output terminal of voltage stabilizer is connected with the reference voltage input terminal of amplifying circuit, the output terminal of amplifying circuit is connected with the input end of current/charge-voltage convertor, and the output terminal of current/charge-voltage convertor is connected with output interface.
Described voltage stabilizer is the voltage stabilizer that is output as 2.5V.
The utility model circuit is simple, a monolithic chip CAV424 and some simple peripheral components have only been used, do not use all responsible circuit of traditional grain moisture sensor, cost is low, stable performance, and by temperature-compensation circuit temperature factor is taken into account the influence of measurement of water ratio, and the extraction of temperature signal, conversion, transmission all the output signal magnitude with the Sensor core part is consistent, be convenient to follow-up signal Processing and demonstration.
Description of drawings
Fig. 1 is the equivalent circuit diagram of capacitance type sensor;
Fig. 2 is the theory diagram of capacitance type sensor of the prior art;
Fig. 3 is the pin figure of the used translation interface integrated circuit of the utility model;
Fig. 4 is the peripheral circuit connection diagram of the used translation interface integrated circuit of the utility model;
Fig. 5 is the circuit theory diagrams of embodiment one;
Fig. 6 is the temperature-compensation circuit of embodiment two and the amplification and the change-over circuit schematic diagram of signal;
Fig. 7 is for using the theory diagram that the utility model is measured in real time.
Embodiment
Below in conjunction with specific embodiment and accompanying drawing the technical solution of the utility model is described in detail.
The utility model comprises the capacitance type sensor that is used to measure cereal electric capacity, translation interface integrated circuit, the feed circuit that are used to handle the capacitance type sensor signal, the signal output part of described capacitance type sensor is connected with the measuring junction of translation interface integrated circuit, being used to of translation interface integrated circuit exports with the output terminal of the linear voltage of the cereal electric capacity of capacitance type sensor signal end output and is connected with output interface, the input end of described feed circuit is by the power supply interface external power supply, and output terminal is connected with the power end of translation interface integrated circuit.
In the utility model, it is the integrated circuit of CAV424 that described translation interface integrated circuit can adopt the model of German AMG Co. exploitation.CAV424 has bigger application flexibility, is the complete translation interface integrated circuit of the various capacitance type sensor signals of multiduty processing, and it has simultaneously, and signals collecting (electric capacitance change relatively) is handled and the function of differential voltage output.CAV424 can measure the difference of a measured capacitance and reference capacitance.It can detect 10pF to the capacitance of 2nF (being 5% to 100% variation range of reference capacitance value).Its voltage output stage is a differential signal that can reach Vmax=± 1.4V, can carry out subsequent treatment more conveniently.The limb figure of CAV424, peripheral circuit connection layout are respectively as shown in Figure 3, Figure 4.The oscillation frequency of CAV424 is shown below:
From following formula as seen, the oscillation frequency of CAV424 is to be determined by factors such as reference capacitance, external circuitses, is a steady state value in measuring process.Therefore, can solve the problem of frequency stabilization, guarantee the constancy of dielectric loss.
The circuit theory diagrams of embodiment one as shown in Figure 5.
Among Fig. 5, Cmois is the electric capacity that cereal presented that the cereal container of moisture transducer contain to carry certain water percentage, just the amount that will measure of this circuit; Used capacitance type sensor is the PF3000 type sensor of U.S. AgLeader company in the present embodiment, and LM7805 is used for doing the stabilized voltage supply of 5V, and external one direct supply greater than 5V is exported a stable 5V voltage; The CAV424 chip is a core devices, more external devices, and wherein Cosc is for determining the reference oscillator electric capacity of frequency; Cx1 is a reference capacitor; Cfix is a fixing electric capacity, constitutes Measurement of capacitor with the Cmois sum, can go out 5%～100% variation capacitance of reference capacitance value by circuit measuring; CL1, CL2 are the external electric capacity with the composition wave filter of chip; RL1, RL2 is for regulating the resistance of output differential voltage gain; Rcx1, Rcx2, Rosc are respectively the resistance of regulating chip integrator electric current; Cvm is a load capacitance, to stablize the fixedly output of 2.5V voltage; The fixing 2.5V voltage output of 5 pin output voltage V out and 6 pin constitutes difference output, its size and the linear corresponding relation of measured capacitance amount Cmois.
For the ease of follow-up signal Processing, can also be provided with amplifying circuit and current/charge-voltage convertor in the present embodiment, as shown in Figure 6, LM358T U3 is an operational amplifier; AD694 U4 is voltage-current converter, it can be the electric current of 4～20mA with certain voltage transitions, after the amplification of voltage signal through LM358T U3 of voltage output end 5 pin of CAV424 chip output, the output of 6 pin, be converted to the electric current output of 4～20mA through superpotential-current converter AD694 U4.
Because the electric capacity of cereal is not only relevant with the water percentage of itself, and relevant with factors such as the compactness of cereal, temperature.The cereal compactness changes not quite in the on-line measurement, can ignore basically, but the temperature of cereal is a tangible influence factor.Therefore need to consider temperature compensation, therefore can in the utility model, increase by a temperature signal measurement circuit, compensate by demarcating.Concrete as embodiment two.
In embodiment two, comprise as being used among the embodiment one measure cereal electric capacity capacitance type sensor, be used to handle translation interface integrated circuit, the feed circuit of capacitance type sensor signal, in order to carry out temperature compensation, increased temperature-compensation circuit in the present embodiment, because it is identical with embodiment one to be used to measure the capacitance type sensor of cereal electric capacity, the translation interface integrated circuit that is used to handle the capacitance type sensor signal, feed circuit, do not repeat them here this temperature-compensation circuit of only detailed explanation.Described temperature-compensation circuit as shown in Figure 6, comprise temperature sensor AD 590, amplifying circuit LM358T U6, current/charge-voltage convertor AD694 U7, voltage stabilizer LT1019 U5, described temperature sensor AD 590 is used to detect the grain temperature of on-line measurement, and this temperature signal is transported to amplifying circuit LM358T U6, after the signal amplification through LM358T U6, output to current/charge-voltage convertor AD694 U7, be converted to the electric current output of 4～20mA through it.Wherein, the burning voltage of voltage stabilizer LT1019 U5 output 2.5V, 78L09 U8 is a stabilized voltage supply, is used to provide the burning voltage of 9V.
When using the utility model and measure in real time, its theory diagram as shown in Figure 7, the differential voltage of sensor outputs to the conversion module be converted to the electric current of 4～20mA through superpotential-current converter after, outputs to processing module after the conversion through the conversion module; The temperature signal of temperature sensor output through amplification after superpotential-current converter outputs to the conversion module after being converted to the electric current of 4～20mA, also output to processing module after the conversion through the conversion module, after the processing module processing, output to and demonstrate humidity value and temperature value in the display.
Concrete measuring process is: the utility model is installed on the united reaper, and after the energising, voltage signal be measured and be converted to the electric capacity of the cereal in the sensor will by the translation interface integrated circuit; The temperature signal of cereal also is detected simultaneously and converts voltage signal to; By conversion of signals, two groups of conversion of signals are become the current signal of 4～20mA; Current signal transfers to the controller of system for measuring yield through over-sampling and processing, demonstrates humidity value and temperature value on grain yield monitor.
Cereal in elevator to the process in car storehouse, a part will pour into the sampling passage by sample tap, when passage satisfies to the degree being convenient to measure, the level sensor of settling on the passage will begin action, the drive motor entry into service drives will take a sample cereal loopback in the grain elevator only in the passage of spiral conveyer.This process is gone round and begun again, and impels cereal to bring in constant renewal in, thereby the online in real time of having finished grain moisture is measured.
It should be noted last that: above embodiment is the unrestricted the technical solution of the utility model in order to explanation only, although the utility model is had been described in detail with reference to the foregoing description, those of ordinary skill in the art is to be understood that: still can make amendment or be equal to replacement the utility model, and not breaking away from any modification or partial replacement of spirit and scope of the present utility model, it all should be encompassed in the middle of the claim scope of the present utility model.
Claims (8)
1, a kind of grain moisture real-time measurement apparatus, it is characterized in that: comprise the capacitance type sensor that is used to measure cereal electric capacity, be used to handle the translation interface integrated circuit of capacitance type sensor signal, feed circuit, the signal output part of described capacitance type sensor is connected with the measuring junction of translation interface integrated circuit, being used to of described translation interface integrated circuit exports with the output terminal of the linear voltage of the cereal electric capacity of capacitance type sensor signal end output and is connected with output interface, the input end of described feed circuit is by the power supply interface external power supply, and output terminal is connected with the power end of translation interface integrated circuit.
2, grain moisture real-time measurement apparatus according to claim 1 is characterized in that: the measuring junction at described translation interface integrated circuit is parallel with the electric capacity that the cereal electric capacity that is used for presenting with cereal to be measured constitutes Measurement of capacitor.
3, grain moisture real-time measurement apparatus according to claim 1, it is characterized in that: between the output terminal of described translation interface integrated circuit and output interface, be connected with amplifying circuit and current/charge-voltage convertor in turn, the output terminal of translation interface integrated circuit is connected with the input end of amplifying circuit, the output terminal of amplifying circuit is connected with the input end of current/charge-voltage convertor, and the output terminal of current/charge-voltage convertor is connected with output interface.
4, according to the arbitrary described grain moisture real-time measurement apparatus of claim 1-3, it is characterized in that: described translation interface integrated circuit is that the model that German AMG Co. produces is the integrated circuit with signal acquisition process, differential voltage output function of CAV424.
5, grain moisture real-time measurement apparatus according to claim 3, it is characterized in that: described amplifying circuit is an operational amplifier, two input end is connected with two output terminals of translation interface integrated circuit respectively, and the output terminal of operational amplifier is connected with the input end of current/charge-voltage convertor.
6, according to claim 3 or 5 described grain moisture real-time measurement apparatus, it is characterized in that: described current/charge-voltage convertor is that model is the integrated circuit of AD694.
7, grain moisture real-time measurement apparatus according to claim 1, it is characterized in that: this measurement mechanism also is provided with temperature-compensation circuit, described temperature-compensation circuit comprises temperature sensor, amplifying circuit, current/charge-voltage convertor, voltage stabilizer, the signal end of described temperature sensor is connected with the input end of amplifying circuit, the output terminal of voltage stabilizer is connected with the reference voltage input terminal of amplifying circuit, the output terminal of amplifying circuit be connected with the input end of current/charge-voltage convertor, the output terminal of current/charge-voltage convertor is connected with output interface.
8, grain moisture real-time measurement apparatus according to claim 7 is characterized in that: described voltage stabilizer is the voltage stabilizer that is output as 2.5V.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200420077708 CN2709978Y (en) | 2004-07-05 | 2004-07-05 | Device for real-time measuring moisure of grain |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200420077708 CN2709978Y (en) | 2004-07-05 | 2004-07-05 | Device for real-time measuring moisure of grain |
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| CN2709978Y true CN2709978Y (en) | 2005-07-13 |
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| CN 200420077708 Expired - Fee Related CN2709978Y (en) | 2004-07-05 | 2004-07-05 | Device for real-time measuring moisure of grain |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106770507A (en) * | 2017-01-16 | 2017-05-31 | 南京信息工程大学 | A kind of humidity detector and method based on electric capacity |
| CN108732208A (en) * | 2018-05-22 | 2018-11-02 | 上海交通大学 | A kind of Crop moisture sensor and the method for measuring grain moisture |
| CN109900754A (en) * | 2019-04-17 | 2019-06-18 | 岭南师范学院 | A kind of veneer impulse type grain quality measuring system and its application method |
| CN112345559A (en) * | 2019-08-06 | 2021-02-09 | 中国农业机械化科学研究院 | Online grain moisture detection device and detection method of combine harvester |
-
2004
- 2004-07-05 CN CN 200420077708 patent/CN2709978Y/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106770507A (en) * | 2017-01-16 | 2017-05-31 | 南京信息工程大学 | A kind of humidity detector and method based on electric capacity |
| CN108732208A (en) * | 2018-05-22 | 2018-11-02 | 上海交通大学 | A kind of Crop moisture sensor and the method for measuring grain moisture |
| CN108732208B (en) * | 2018-05-22 | 2020-11-06 | 上海交通大学 | Grain moisture sensor and method for measuring grain moisture |
| CN109900754A (en) * | 2019-04-17 | 2019-06-18 | 岭南师范学院 | A kind of veneer impulse type grain quality measuring system and its application method |
| CN112345559A (en) * | 2019-08-06 | 2021-02-09 | 中国农业机械化科学研究院 | Online grain moisture detection device and detection method of combine harvester |
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| CF01 | Termination of patent right due to non-payment of annual fee |