CN104198348B - System and method for PM2.5 concentration detection based on photoelectric integration - Google Patents
System and method for PM2.5 concentration detection based on photoelectric integration Download PDFInfo
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- CN104198348B CN104198348B CN201410470210.7A CN201410470210A CN104198348B CN 104198348 B CN104198348 B CN 104198348B CN 201410470210 A CN201410470210 A CN 201410470210A CN 104198348 B CN104198348 B CN 104198348B
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Abstract
The invention belongs to the technical field of PM2.5 concentration detection and particularly relates to a system and a method for PM2.5 concentration detection based on photoelectric integration. The system consists of a ventilation chamber, a measurement chamber and a detection part, wherein the ventilation chamber is separated from the measurement chamber by a gas cutter, and the other end of the measurement chamber is connected with a detection channel; the detection part is arranged at the periphery of the detection channel and consists of an optical detection part, a power detection part and a data processing part; the optical detection part and the power detection part are respectively connected with the data processing part. The concentration of PM2.5 particles is respectively detected through optical detection and power detection, and then, fusion calculation is carried out on two detection signals by a kalman filtering algorithm. As no laser generator is used in the invention, the cost of the system is greatly reduced. Meanwhile, detection data is obtained by the detection method adopting two different principles, and the actual value is obtained through fusion calculation, so that the detection precision of the system can be ensured.
Description
Technical field
The invention belongs to PM2.5 Concentration Detections field, more particularly to a kind of PM2.5 concentration inspection based on light electro' asion
Examining system and detection method.
Background technology
PM2.5 is also cried can enter lung granule, refer to particulate matter of the aerodynamic diameter less than or equal to 2.5 microns, and it is in air
The atmospheric aerosol of middle formation has bigger extinction coefficient compared to the aerosol that the particulate matter of remaining particle size range is formed, and is
This year common " haze " phenomenon major pollutants.Because the specific surface area of PM2.5 is big, easily adsorb poisonous and harmful substances,
And the reaction bed of atmospheric reaction thing is provided, and secondary pollution is generated, thus it is very big to environmental hazard.
After illumination is mapped to PM2.5 aerosoies, because particulate matter is to scattering of light, absorption and dissipates so that light is in space
In light distribution and particle concentration there is dependency relation.Based on this principle, the product of the market mainstream is mostly based on laser
Scattering formula PM2.5 concentration meter, although accuracy of detection is high, reproducible, but equipment manufacturing cost is high, it is difficult to popularize.
The content of the invention
To solve problem above, the purpose of the present invention is that a kind of precision of design is suitable with laser scattering type detector, sexual valence
Than high the PM2.5 concentration detection systems based on light electro' asion and detection method, to meet demand of the market to such product.
To reach object above, the technical scheme for adopting of the present invention for：
The detecting system is made up of breather chamber, measuring chamber, detection part；The measuring chamber is front wide and rear narrow infundibulate,
Separated by gas sickle between breather chamber and the wide end of measuring chamber；The narrow end of measuring chamber is connected with sense channel；
The detection part is arranged on around sense channel, by light detecting portion, electro-detection part and data processing section
Composition；Light detecting portion and electro-detection part are connected respectively with data processing section；
The light detecting portion is made up of photodetector and nonconducting optical glass；The optical glass of annular is arranged on
On sense channel wall, optical glass outside arranges photodetector；
The capacitor and small capacitance detection circuit that the electro-detection part is made up of conductive plate is constituted；Capacitor is arranged
On the sense channel wall at optical glass rear, small capacitance detection circuit is connected with capacitor.
The breather chamber is rectangle with the cross section of measuring chamber junction；The gas sickle is installed for sealing.
The cross section of the sense channel is the rectangle of 5～10mm for length and width.
The data processing division is divided into process circuit and display.
In the system, except optical glass, remainder is opaque material.
Based on the detection method of said detecting system, comprise the following steps：
(1) air containing only PM2.5 to be detected is obtained：
Normal air enters detecting system from the entrance of breather chamber, by gas sickle by the PM2.5 particulate matters in air
With non-PM2.5 particulate separations；Air containing PM2.5 enters measuring chamber, stands after indoor PM2.5 concentration to be measured is stablized and opens
Begin to detect；
(2) detection part work, obtains detection signal, and it is processed：
Photodetector is first turned on, the white light that light source sends is passed through after the air containing PM2.5, due to PM2.5
Refraction, scattering and absorption of the grain to light, the intensity by the light of the air containing PM2.5 is related to the concentration of PM2.5 granules, position
Light intensity signal is converted into into the signal of telecommunication in the probe of light source opposite side, first via light detecting signal is formed；
Then electro-detection part is opened, the capacitance of capacitor is relevant with the concentration of PM2.5 granules, examines by small capacitance
The capacitance of capacitor is converted into the signal of telecommunication by slowdown monitoring circuit, forms the second road power detection signal；
The two paths of signals for being obtained is carried out respectively signal processing, the normal voltage of 0-5V is converted to by filtering, shaping
Signal, through analog digital conversion data processing section is sent into；
(3) Kalman filtering algorithm is used, fusion calculation is carried out to two-way detection signal：
Data processing section is received after signal, and the light detecting signal of the feeding of synchronization and power detection signal are stored
In the same row of two-dimensional array, light detecting signal is stored in the first row of two-dimensional array according to time order and function, and power detection signal is pressed
The second row of two-dimensional array is stored sequentially according to time order and function；Data processing section is according to Kalman filtering algorithm to two paths of signals
Fusion calculation is carried out, result of calculation is stored in another one-dimension array, output display is carried out when needing.
Beneficial effects of the present invention are：
The light detecting portion of the present invention is based on same physical process, but this with existing frequently-used laser scattering type detector
The physical quantity of invention detection is the light intensity through aerosol particle thing, maximum compared with the equipment of detection scattered light intensity
Advantage is also to obtain preferably detection characteristic using white light, can substantially reduce system cost.
Meanwhile, detection data is obtained with the detection method of two kinds of different principles, and actual value is obtained by fusion calculation, can
To ensure the accuracy of detection of system.
Additionally, by adjusting blending algorithm parameter, it is possible to achieve any mapping relations, to change the result of fusion calculation,
Therefore system is reduced to the degree of dependence of hardware precision, testing result can be modified by way of software compensation, is dropped
Low hardware production precision, it is also possible to reduce system cost.
Description of the drawings
Fig. 1 is the workflow schematic diagram of the present invention.
Fig. 2 is the system structure diagram of the present invention.
When Fig. 3 is using circle cutter, the system structure diagram from terms of air intake direction.
Fig. 4 is the structure chart that small capacitance detects circuit.
Fig. 5 is the flow chart of blending algorithm.
Fig. 6 is the result of blending algorithm.
Label in figure：
1- breather chambers, 2- cutting heads, 3- measuring chambers, 4- process circuits and display, 5- photodetectors, 6- optics glass
Glass, 7- capacitors.
Specific embodiment
The invention provides a kind of PM2.5 concentration detection systems and detection method based on light electro' asion, with reference to attached
The present invention will be further described with specific embodiment for figure.
The Cleaning Principle and flow process of the present invention as shown in figure 1, system structure is as shown in Fig. 2 label Cx represents measurement electric capacity,
D represents air intake direction.
The system is made up of breather chamber 1, measuring chamber 3, detection part；The measuring chamber 3 is front wide and rear narrow infundibulate, is led to
Separated by gas sickle 2 between the wide end of air chamber 1 and measuring chamber 3；The narrow end of measuring chamber 3 is connected with sense channel.Ventilation
Room 1 is rectangle with the cross section of the junction of measuring chamber 3；The gas sickle 2 is circular or rectangle, is installed using sealing, its
Function is that normal air is divided into into part and remainder containing only PM2.5 granules, when using circular gas sickle 2,
It is as shown in Figure 3 from gas sickle 2 in terms of air intake direction.
To reduce sensor cost, height is unsuitable excessive at the detection of measuring chamber 3, otherwise can cause to measure capacitance it is too small,
Transmitted intensity is too small, thus it requires system is from the higher sensor of sensitivity, and then improves cost, while height at detection
Unsuitable too small, wind speed increment crosses conference otherwise at detection causes actual wind speed fluctuation larger, affects certainty of measurement, sense channel
Cross section is proper for the rectangle that length and width are 5～10mm.
Detection part is arranged on around sense channel, is made up of light detecting portion, electro-detection part and data processing section；
Light detecting portion and electro-detection part are connected respectively with data processing section.Data processing division is divided into process circuit and display 4,
On the outer wall of measuring chamber 3.
The light detecting portion is made up of photodetector 5 and nonconducting optical glass 6；The optical glass 6 of annular sets
Put on sense channel wall, the outside of optical glass 6 arranges photodetector 5.Light detecting portion and existing frequently-used laser light scattering
Formula detector is based on same physical process, but the physical quantity of present invention detection is the light intensity through aerosol particle thing, with
The equipment of detection scattered light intensity is compared, and maximum advantage is also to obtain preferably detection characteristic using white light, can be significantly
Reduce system cost.
The capacitor 7 and small capacitance detection circuit that the electro-detection part is made up of conductive plate is constituted；Capacitor 7 sets
Put on the sense channel wall at the rear of optical glass 6, small capacitance detection circuit is connected with capacitor 7.The original of electro-detection part
Reason is that the electrology characteristic of PM2.5 granules is different from air, and the dielectric that the air of the PM2.5 granules containing variable concentrations has is normal
Number difference, and then cause to measure electric capacity difference, can obtain measurement capacitance pass corresponding with PM2.5 granule densities by demarcating
System.
The structure of small capacitance detection circuit is as shown in Figure 4.
Label i indication circuits input in circuit, Cx represents testing capacitance, and Cr represents reference capacitance, and U is an operation amplifier
Device, R1, R2, R3 and Rf represent resistance.
The principle of circuit work is：Two switches are first closed, now two electric capacity all discharge, and are also turned on two electronics
Switch, is charged, according to the definition of electric capacity to testing capacitance and reference capacitance simultaneously by size identical current source：
C=Q/U=i Δ t/U,
In electric capacity charging process, capacitor voltage at both ends meets：
U=i Δ t/C,
After operational amplifier carries out subtraction, the voltage difference of the two ends input of operational amplifier has following relation：
Obviously, output voltage U0The charging interval is proportional to, its proportionality coefficient reflects CxValue.
Due to capacitor charging time it is shorter, while to avoid relaxation phenomena, the unsuitable last longer of said process.
To avoid interference light detecting portion accuracy of detection, the system in addition to nonconducting optical glass 6, adopt by remainder
With opaque material, while in signal processing, using the method for difference the interference of ambient light is removed.
The step of detecting system carries out PM2.5 Concentration Testings be：
(1) air containing only PM2.5 to be detected is obtained：
Normal air enters detecting system from the entrance of breather chamber 1, by gas sickle 2 by the PM2.5 granules in air
Thing and non-PM2.5 particulate separations；Air containing PM2.5 enters measuring chamber 3, stands PM2.5 concentration in room 3 to be measured and stablizes
After start detection；
(2) detection part work, obtains detection signal, and it is processed：
Photodetector 5 is first turned on, the white light that light source sends is passed through after the air containing PM2.5, due to PM2.5
Refraction, scattering and absorption of the grain to light, the intensity by the light of the air containing PM2.5 is related to the concentration of PM2.5 granules, position
Light intensity signal is converted into into the signal of telecommunication in the probe of light source opposite side, first via light detecting signal is formed；
Then electro-detection part is opened, the capacitance of capacitor 7 is relevant with the concentration of PM2.5 granules, by small capacitance
The capacitance of capacitor 7 is converted into the signal of telecommunication by detection circuit, forms the second road power detection signal；
The two paths of signals for being obtained is carried out respectively signal processing, the normal voltage of 0-5V is converted to by filtering, shaping
Signal, through analog digital conversion data processing section is sent into；
(3) Kalman filtering algorithm is used, fusion calculation is carried out to two-way detection signal：
The essence of data fusion is according to the multiple detected values containing actual concentration, to search out reflecting for detected value and actual value
Relation is penetrated, using Kalman filtering algorithm.Kalman filtering algorithm is the optimal solution under classical linear regression is assumed, can maximum journey
Avoid interference of the random noise to Detection results degree.Fig. 5 is the process of Kalman filtering algorithm, and region I represents prediction in figure
Link, region II represents amendment link.
Algorithm assumes that the mathematical model of system is made up of formula (1), formula (2).
S (k)=AS (k-1)+w (k-1) (1)
Z (k)=CS (k)+v (k) (2)
Wherein, k represents kth time fusion, and S represents actual value, and w represents the noise introduced in model, and Z represents detected value, v tables
Show the noise introduced during detection, A, C are known coefficient.All of above parameter can be scalar form, or matrix form.
Formula (1) is meant that in the case of without outside input, the virtual condition of system can be unknowable due to some
Factor fluctuate within the specific limits, if macroscopic view consider, negligible latter.In this example, although PM2.5's is dense in air
Degree can by discharging, the factor such as weather affected, but Kalman filtering algorithm is the filtering algorithm for being based on detected value, so not
Affect filter effect.
Formula (2) is meant that, current detected value except relevant with actual value, can also introduce some it is not eliminable with
Random error in machine noise, i.e. detection process.
When filtering starts, first the light detecting signal and power detection signal of the feeding of synchronization are stored in into two-dimensional array
Same row, light detecting signal is stored in the first row of two-dimensional array according to time order and function, and power detection signal is suitable according to time order and function
Sequence is stored in the second row of two-dimensional array, the matrix of some row of one 2 row of formation.Then filtering algorithm is started, according to formula
Sequentially, often calculate once, you can obtain the actual value with the moment corresponding to current detected value.
E ' (k)=AE (k-1) AT+Q (3)
H (k)=E ' (k) CT/ (CE ' (k) CT+R) (4)
E (k)=(I-H (k) C) E ' (k) (5)
Wherein,It is the result of fusion calculation, I represents unit matrix, and exponent number is identical with other parts in formula, remaining is meter
Pilot process value during calculation.The conjugate transpose of subscript " T " representing matrix, is exactly turning for matrix in the case of occurring without imaginary number
Put, if all scalar operations, can ignore.
Q and R are the parameter informations of aforementioned adjustment filtering algorithm effect, when Q is equal to the random disturbance w in model
Covariance matrix, R be equal to measurement process in random disturbance v covariance matrix when, the result of calculation of filtering algorithm is most
Alright.In practice, the value that can pass through change Q and R adjusts the performance of filtering algorithm.
Fig. 6 is the result of blending algorithm, solid line correspondence actual value in figure, the result of dotted line correspondence fusion calculation, and remaining two
Bar curve corresponds to respectively a measured value.Can see, it is larger but containing the measured value of true value information according to two-way error, melt
Total result calculated is more or less the same with actual value.
Claims (6)
1. a kind of PM2.5 concentration detection systems based on light electro' asion, are made up of breather chamber (1), measuring chamber (3), detection part,
Characterized in that, the measuring chamber (3) be front wide and rear narrow infundibulate, breather chamber (1) and measuring chamber (3) wide end between by gas
Body sickle (2) is separated；The narrow end of measuring chamber (3) is connected with sense channel；
The detection part is arranged on around sense channel, is made up of light detecting portion, electro-detection part and data processing section；
Light detecting portion and electro-detection part are connected respectively with data processing section；
The light detecting portion is made up of photodetector (5) and nonconducting optical glass (6)；The optical glass (6) of annular
It is arranged on sense channel wall, optical glass (6) outside arranges the relative photodetector (5) in two positions；
The capacitor (7) and small capacitance detection circuit that the electro-detection part is made up of conductive plate is constituted；Capacitor (7) sets
Put on the sense channel wall at optical glass (6) rear, small capacitance detection circuit is connected with capacitor (7).
2. PM2.5 concentration detection systems based on light electro' asion according to claim 1, it is characterised in that the ventilation
Room (1) is rectangle with the cross section of measuring chamber (3) junction；The gas sickle (2) is installed for sealing.
3. PM2.5 concentration detection systems based on light electro' asion according to claim 1, it is characterised in that the detection
The cross section of passage is the rectangle of 5～10mm for length and width.
4. PM2.5 concentration detection systems based on light electro' asion according to claim 1, it is characterised in that the data
Process part is process circuit and display (4).
5. PM2.5 concentration detection systems based on light electro' asion according to claim 1, it is characterised in that the system
In, except optical glass (6), remainder is opaque material.
6. a kind of detection method based on detecting system described in claim 1, it is characterised in that comprise the following steps：
(1) air containing only PM2.5 to be detected is obtained：
Normal air enters detecting system from the entrance of breather chamber (1), by gas sickle (2) by the PM2.5 granules in air
Thing and non-PM2.5 particulate separations；Air containing PM2.5 enters measuring chamber (3), stands the interior PM2.5 concentration of room (3) to be measured
Start detection after stable；
(2) detection part work, obtains detection signal, and it is processed：
Photodetector (5) is first turned on, the white light that light source sends is passed through after the air containing PM2.5, due to PM2.5 granules
Refraction, scattering and absorption to light, the intensity by the light of the air containing PM2.5 is related to the concentration of PM2.5 granules, is located at
Light intensity signal is converted into the signal of telecommunication by the probe on the outside of optical glass (6), forms first via light detecting signal；
Then electro-detection part is opened, the capacitance of capacitor (7) is relevant with the concentration of PM2.5 granules, examines by small capacitance
The capacitance of capacitor (7) is converted into the signal of telecommunication by slowdown monitoring circuit, forms the second road power detection signal；
The two paths of signals for being obtained is carried out respectively signal processing, the standard voltage signal of 0-5V is converted to by filtering, shaping,
Data processing section is sent into through analog digital conversion；
(3) Kalman filtering algorithm is used, fusion calculation is carried out to two-way detection signal：
Data processing section is received after signal, and the light detecting signal and power detection signal of the feeding of synchronization are stored in into two
The same row of dimension group, light detecting signal is stored in the first row of two-dimensional array according to time order and function, power detection signal according to when
Between sequencing be stored in the second row of two-dimensional array；Data processing section is carried out according to Kalman filtering algorithm to two paths of signals
Fusion calculation, result of calculation is stored in an one-dimension array, and output display is carried out when needing.
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| CN104573358B (en) * | 2014-12-31 | 2018-01-12 | 北京林业大学 | Detect the method and device of PM2.5 mass in forest belt |
| CN105806756B (en) * | 2016-01-30 | 2019-01-18 | 济南大陆机电股份有限公司 | A method of indoor and outdoor pm2.5 monitoring result is corrected using meteorologic parameter |
| CN107884317A (en) * | 2016-09-29 | 2018-04-06 | 香港城市大学 | Particulate matter sensors |
| CN107607449A (en) * | 2017-08-21 | 2018-01-19 | 黑龙江科技大学 | A kind of device and method for detecting particulate matter quality concentration |
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| JP2003035655A (en) * | 2001-07-24 | 2003-02-07 | Shimadzu Corp | Method and equipment for measuring floating particulate material |
| CN101441718A (en) * | 2008-12-19 | 2009-05-27 | 福建三元达通讯股份有限公司 | Sensor information fuse device and method |
| CN103105611B (en) * | 2013-01-16 | 2016-01-20 | 广东工业大学 | A kind of distributed multi-sensor Intelligent information fusion method |
| CN103454194B (en) * | 2013-09-05 | 2015-09-23 | 江苏物联网研究发展中心 | PM2.5 pick-up unit and manufacture method thereof |
| CN203595650U (en) * | 2013-10-24 | 2014-05-14 | 华北电力大学 | Simple PM 2.5 detecting instrument device |
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