Background technology
Grain moisture content content influence grain physics, chemistry and biological nature are the key indexs of grain quality, directly influence the process such as purchase, transportation, storage, processing trade of grain.Microwave has very strong penetrability as the very high electromagnetic wave of a kind of frequency, and what it detected is not only the moisture on grain surface, can also under harmless situation, detect the inner moisture of grain.Microwave Measurement mechanism is to utilize microwave action to calculate the moisture of material in change informations such as material generation amplitude attenuations.Because the kind and the coating of particles of grain vary in size; The variation of grain density degree when causing online the detection; Make that grain relative dielectric constant and dielectric loss angle are variant, thereby cause change in information such as microwave power, amplitude that it is inaccurate that formation influences testing result.Therefore, the microwave moisture detecting method needs supplementary means to carry out density compensation.
At present, the material density detection technique mainly contains following two kinds of technical schemes:
The one, volumetric method.This method is that material to be measured is filled in the container of a known volume, and promptly the volume of material is known, through measuring the weight of material, obtains the density value of material.Concrete computing formula is
ρ is the density of material in the formula, and M is a weight, and V is a volume.This method is simple, directly perceived, relatively more accurate.Shortcoming is to be not easy to online detection, and the moisture in the material has certain influence to measurement result.
The 2nd, ray detection method.This method is that the ray that is produced by radioactive source is passed tested material; Wherein a part of ray is by material scattering and absorption; The detector that the remainder ray is installed in another side receives, and according to the average absorption rule of ray attenuation rule and tested material, extrapolates the density of tested material.Its principle is: ρ=(lnI
0-lnI)/(ud), I in the formula
0Be the incident intensity before the transmission of radiation material, I is the outgoing intensity behind the transmission of radiation material, and u is the absorption coefficient of material, and d is the thickness that ray penetrates material, and ρ is the density of material.This method speed is fast, measuring accuracy is high, noncontact, be easy to online detection.Shortcoming is that cost is higher, has certain potential safety hazard, and the thickness of tested material has appreciable impact to measurement result.
Along with further developing of microwave on-line grain moisture content detection technique, grain Density Detection and Study on Compensation Technique are the main research and development directions in present this field.
Summary of the invention
Technical matters to be solved by this invention is to provide a kind of microwave on-line grain moisture content detection device and method thereof, is used to solve prior art and carries out grain moisture content and detect and to cause the inaccurate problem of testing result.
To achieve these goals, the invention provides a kind of microwave on-line grain moisture content detection device, comprise the microcontroller, interface circuit, the computing machine that connect in order, it is characterized in that, also comprise:
HF signal generator is used to produce high-frequency signal;
High-frequency signal receiver is used to pick up the said high-frequency signal that grain is crossed in transmission;
Signal condition and testing circuit; Connect said HF signal generator, said high-frequency signal receiver; Said high-frequency signal before the said grain of said high-frequency signal, transmission that is used for said high-frequency signal receiver is picked up carries out amplitude and phase difference detects; And the water content detection result who obtains is sent to said computing machine through said microcontroller, said interface circuit, according to the density compensation algorithm said water content detection result is carried out density compensation by said computing machine.
Described microwave on-line grain moisture content detection device, wherein, said high-frequency signal is the high-frequency signal of frequency greater than 100MHz.
Described microwave on-line grain moisture content detection device; Wherein, the attenuation rate and the absorption coefficient of the said high-frequency signal before the said grain of said high-frequency signal, transmission that picks up according to said high-frequency signal receiver of said signal condition and testing circuit obtain said water content detection result.
Described microwave on-line grain moisture content detection device, wherein, said microcontroller carries out A/D conversion back to said water content detection result and is sent to said computing machine through said interface circuit.
Described microwave on-line grain moisture content detection device, wherein, said computing machine carries out density compensation with following formula to said water content detection result:
Wherein, ρ
wBe density reckoning value;
Be the phase difference measurement value; Δ A is the difference in magnitude measured value; a
1, a
2Be weighting coefficient; B is for calculating constant; a
1, a
2, b obtains through system identifying method in advance;
M
s=M
c+η·ρ
w (2)
Wherein, M
sBe the moisture value behind the density compensation; M
cBe the moisture measurement value; η is the density compensation coefficient; η obtains through data statistical approach in advance.
To achieve these goals, the present invention also provides a kind of microwave on-line grain moisture content detection method, it is characterized in that, comprising:
Step 1 produces high-frequency signal, and said high-frequency signal and grain are interacted;
Step 2 is picked up the said high-frequency signal that said grain is crossed in transmission;
Step 3 is carried out amplitude and phase difference detection to the said high-frequency signal before the said grain of said high-frequency signal, transmission that is picked up, and obtains the water content detection result, and according to the density compensation algorithm said water content detection result is carried out density compensation.
Described microwave on-line grain moisture content detection method, wherein, in the said step 1, said high-frequency signal is the high-frequency signal of frequency greater than 100MHz.
Described microwave on-line grain moisture content detection method wherein, in the said step 3, further comprises:
According to the attenuation rate of the said high-frequency signal before the said said grain of said high-frequency signal, transmission that picks up and the step that absorption coefficient obtains said water content detection result.
Described microwave on-line grain moisture content detection method wherein, in the said step 3, further comprises:
Before carrying out said density compensation, earlier said water content detection result is carried out the step of A/D conversion.
Described microwave on-line grain moisture content detection method wherein, in the said step 3, further comprises:
Said water content detection result is carried out the step of density compensation with following formula:
Wherein, ρ
wBe density reckoning value;
Be the phase difference measurement value; Δ A is the difference in magnitude measured value; a
1, a
2Be weighting coefficient; B is for calculating constant; a
1, a
2, b obtains through system identifying method in advance;
M
s=M
c+η·ρ
w (2)
Wherein, M
sBe the moisture value behind the density compensation; M
cBe the moisture measurement value; η is the density compensation coefficient; η obtains through data statistical approach in advance.
Useful technique effect of the present invention is:
Compared with prior art, the present invention adopts auxiliary high frequency signal amplitude and phase difference detection technique, extrapolates the density of tested grain, again microwave water content detection result is carried out density compensation, solves grain size and density influence.The present invention proposes the variation of adopting high-frequency signal to act on the tested grain and causing amplitude and phase place; Through Differential Detection technology and density compensation algorithm; Reached microwave water content detection and the incoherent purpose of grain density, solved the influence problem of grain density preferably microwave water content detection result.
Describe the present invention below in conjunction with accompanying drawing and specific embodiment, but not as to qualification of the present invention.
Embodiment
Below in conjunction with accompanying drawing and embodiment technical scheme of the present invention is made further more detailed description.
As shown in Figure 1, be microwave on-line grain moisture content detection device structural representation of the present invention.This moisture content detection device 100 comprises: HF signal generator 1, high-frequency signal receiver 3, signal condition and testing circuit 4, microcontroller 5, interface circuit 6, computing machine 7 and density compensation algorithm 8.Wherein core component is signal condition and testing circuit 4, density compensation algorithm 8.
High-frequency signal and grain 2 (being tested material) that HF signal generator 1 produces interact, and the high-frequency signal that grain 2 is crossed in a part of transmission is picked up by high-frequency signal receiver 3.The high-frequency signal that is picked up by signal condition and 4 pairs of high-frequency signal receivers 3 of testing circuit carries out shaping, filtering, conversion, accomplishes the difference extraction is carried out in amplitude comparison before and after the transmission high-frequency signal and phase change.Electric signal after 5 pairs of signal conditions of microcontroller and testing circuit 4 handled carries out the A/D conversion, and the result after will changing is sent in the computing machine 7 through interface circuit 6 and handles.Computing machine 7 carries out density through 8 pairs of data that obtain of density compensation algorithm and calculates that the result carries out density compensation to the microwave water content detection, improves the accuracy that moisture content detection device 100 detects.
Particularly, the high-frequency signal that is produced by HF signal generator 1 sees through grain 2, and high-frequency signal receiver 3 is measured the variation of transmission high-frequency signal front and back amplitude, phase place.According to rate of signal attenuation and absorption coefficient, extrapolate the density of grain 2.Through the density compensation algorithm 8 in the computing machine 7, microwave moisture is carried out density compensation again, improved the accuracy that detects.
Wherein, Hi-pass filter, low-pass filter in signal condition and the testing circuit 4, the high-frequency signal that high-frequency signal receiver 3 is picked up carries out filtering, removes undesired signal.To filtered high-frequency signal, carry out the wave shaping conversion through the phase detector in signal condition and the testing circuit 4, obtain the phase change conversion.
Computing machine 7 carries out density through 8 pairs of data that obtain of density compensation algorithm and calculates that the result carries out density compensation to the microwave water content detection, and concrete formula is following:
ρ wherein
wBe density reckoning value;
Be the phase difference measurement value; Δ A is the difference in magnitude measured value; a
1, a
2Be weighting coefficient; B is for calculating constant.a
1, a
2, b obtains through system identifying method in advance.After recording
Δ A, can just can obtain the result that material density is calculated through density prediction equation (1).
Density compensation M
s=M
c+ η ρ
w(2)
Wherein, M
sBe the moisture value behind the density compensation; M
cBe the moisture measurement value; η is the density compensation coefficient.η obtains through data statistical approach in advance.Record M
cCalculate the result with density, just can obtain the moisture value M behind the density compensation through density compensation formula (2)
s
In Fig. 1, it is auxiliary high frequency signal amplitude and the phase difference detection technique that adopts greater than 100MHz that moisture content detection device 100 carries out water content detection, solves the influence of grain density, and the result carries out density compensation to the microwave water content detection.Use high precision time interval measurement technical Analysis signal phase.
In Fig. 1, adopt high-frequency signal amplitude and phase difference detection technique and density compensation algorithm, reached microwave water content detection and the incoherent purpose of grain density.
Moisture content detection device 100 adopts high-frequency signal Density Detection technology to carry out water content detection, and detection speed is fast, precision is high, safe, reliably.Through amplitude and phase difference with tested material effect front and back high-frequency signal are detected, accurately extrapolate the density of tested material.Utilization density compensation algorithm is revised, is compensated microwave water content detection result, has solved the influence problem of the density of tested material to testing result.
As shown in Figure 2, be microwave on-line grain moisture content detection method schematic flow sheet of the present invention.This method flow has been described employing auxiliary high frequency signal method the density of grain (tested material) has been detected; Utilize amplitude and the phase difference detection technique of frequency greater than the 100MHz high-frequency signal; Accomplished reckoning to grain density; Adopt the density compensation algorithm that microwave water content detection result is carried out non-linear correction, improved the reliability and the practicality of microwave on-line grain moisture content detection device.
In Fig. 2, in conjunction with Fig. 1, the step of this method flow specifically comprises:
Step S201 produces high-frequency signal, and high-frequency signal and grain 2 (being tested material) are interacted;
In this step, high-frequency signal is to be the high-frequency signal greater than 100MHz by the frequency that HF signal generator 1 produces;
Step S202, high-frequency signal receiver 3 picks up the high-frequency signal that grain 2 is crossed in transmission;
Step S203; Amplitude and phase change to the high-frequency signal before and after the transmission grain are carried out Differential Detection; Particularly; The high-frequency signal that 4 pairs of high-frequency signal receivers 3 of signal condition and testing circuit pick up is handled, and carries out the difference extraction according to the amplitude of the high-frequency signal after high-frequency signal before the transmission grain 2 and the processing and the variation of phase place again, obtains the water content detection result;
In this step, the processing that the high-frequency signal that 4 pairs of high-frequency signal receivers 3 of signal condition and testing circuit pick up carries out comprises shaping, filtering, conversion; Particularly:
Through Hi-pass filter, the low-pass filter in signal condition and the testing circuit 4, the high-frequency signal that high-frequency signal receiver 3 is picked up carries out filtering, removes undesired signal.To filtered high-frequency signal, carry out the wave shaping conversion through the phase detector in signal condition and the testing circuit 4, obtain the phase change conversion.
Step S204, the electric signal after 5 pairs of signal conditions of microcontroller and testing circuit 4 handled carries out the A/D conversion, and the result after will changing is sent in the computing machine 7 through interface circuit 6 and handles;
Step S205, the data that computing machine 7 transmits through density compensation algorithm 8 interface circuit 6 are carried out density and are calculated that the result carries out density compensation to the microwave water content detection, the accuracy when improving moisture content detection device 100 detections.
In this step, computing machine 7 carries out density through 8 pairs of data that obtain of density compensation algorithm and calculates that the result carries out density compensation to the microwave water content detection, and concrete formula is following:
Wherein, ρ
wBe density reckoning value;
Be the phase difference measurement value; Δ A is the difference in magnitude measured value; a
1, a
2Be weighting coefficient; B is for calculating constant.a
1, a
2, b obtains through system identifying method in advance.After recording
Δ A, can just can obtain the result that material density is calculated through density prediction equation (1).
Density compensation M
s=M
c+ η ρ
w(2)
Wherein, M
sBe the moisture value behind the density compensation; M
cBe the moisture measurement value; η is the density compensation coefficient.η obtains through data statistical approach in advance.Record M
cCalculate the result with density, just can obtain the moisture value M behind the density compensation through density compensation formula (2)
s
In this step, microwave water content detection result is carried out non-linear correction, make testing result uncorrelated, thereby solve the influence problem of grain density testing result with the grain size through auxiliary high frequency signal density backoff algorithm.
In Fig. 2, adopted frequency grain density to be detected, and adopted high-frequency signal amplitude and phase difference detection technique greater than 100MHz auxiliary high frequency signal.
The present invention adopts auxiliary high frequency signal amplitude and phase difference detection technique, solves the influence of grain density, and the result carries out density compensation to the microwave water content detection.
The present invention proposes and adopt high-frequency signal amplitude and phase difference detection technique and density compensation algorithm, reached microwave water content detection and the incoherent purpose of tested material particle density, solved the influence problem of tested material density preferably testing result.
Through the foregoing description, but the method that the knowledge capital invention has adopted the auxiliary high frequency signal that grain density is detected.A little less than the absorption of high-frequency signal to grain moisture content, have good penetrability, can carry out Density Detection fast, precision is higher.The present invention has simultaneously also adopted high-frequency signal amplitude and phase difference detection technique.
The present invention revises/compensates microwave water content detection result through the density compensation algorithm, makes testing result uncorrelated with the grain size, has guaranteed the accuracy that moisture content detection device detects.
Certainly; The present invention also can have other various embodiments; Under the situation that does not deviate from spirit of the present invention and essence thereof; Those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection domain of the appended claim of the present invention.