Background technique
Apple be rich in a variety of needed by human body vitamin and mineral, as vitamin C, vitamin A, carrotene, calcium,
Iron, potassium etc., it has also become one of maximum fruit of consumption figure in the world.The quality of apple will directly determine the purchasing power of consumer
Degree.Due to there is the apple of internal flaw (such as Tissue Browning, watercore, pulp rot etc.) to be difficult to identify that, therefore, selling
Before can not be rejected, this can cause certain economic loss to consumer, generate adverse effect to the sale of apple.Currently,
Common detection method to the apple for having internal flaw is that apple is cut two halves, and visually observing cross section has zero defect.It is this
Manual inspection is not only time-consuming and laborious, also needs destruction institute's sample that can just learn that whether there is or not internal flaws, and exist in Appraisal process
Certain subjectivity.In order to solve this problem, lossless sensing technology is applied in the classification and classification of fruits and vegetables,
In it is most commonly seen with spectrum and image technique.Some scholars are in Successful utilization X-ray and nmr imaging technique detection
Portion's defect apple classifies to apple sample according to image obtained.However, due to this detection method instrument valence
Lattice are expensive, and detection speed is slower, and therefore, X-ray and nmr imaging technique are in detection internal flaw apple practical application
There are certain difficulties.
The internal flaw of apple will will lead to its structural constituent and a degree of change occurs for physical structure, so as to cause
The variation of respective optical characteristic, and then show as the variation of detection optical signal.Therefore, it is seen that/near-infrared spectrum technique is in apple
There are certain potentiality in inside quality detection.Early in the 1960s, some scholars are poor with the optical density (OD) of wavelength points
Different and absorbance difference detects internal brown stain and watercore apple.Later, Upchurch et al. uses similar method, by 720nm
With the ratio of 810nm transmissivity as the index for judging defect apple, and find the increase with apple tissue brown stain, ratio by
It is decrescence small.Vanoli et al. is detected by using the internal portion's defect apple of Time Domain Reflectometry spectral technique, discovery and normal apple phase
Than at wavelength 750nm, the absorption coefficient of internal brown stain apple be will increase, and reduced scattering coefficient reduces;And for watercore apple
Fruit, at wavelength 790nm, absorption coefficient is more much higher than normal apple, and reduced scattering coefficient then accordingly reduces.Further grind
In studying carefully, Vanoli et al. is by linear discriminant analysis, and discovery absorbs at 780nm and reduced scattering coefficient can get preferable point
Class accuracy, the classification accuracy to normal apple are 90%, and internal brown stain apple classification accuracy is 71%.With it is visible/
The development of near-infrared spectrum technique and Chemical Measurement has scholar to start to be established with spectral signature and the relationship of internal flaw apple
Mathematical model carries out identification assessment to defect apple.Khatiwada and McGlone et al. establish apple internal defect and visible/
NIR transmittance spectroscopy offset minimum binary (PLS) regression model, prediction related coefficient can reach 0.9 or more.Torres et al. is logical
It crosses the brown stain principal component analysis (PCA) for establishing visible/Short-wave near-infrared spectroscopy and apple tissue and offset minimum binary differentiates
(PLSDA) model can reach 80% or more to defect apple identification rate.The studies above shows, it is seen that/near infrared spectral transmission is surveyed
Amount can effectively distinguish internal flaw apple and normal apple.It is penetrated entirely however, total transmissivity measurement needs detector to obtain light
Signal after apple, this requires stronger light signal, the signal that otherwise detector obtains may be very faint and lead to letter
It makes an uproar than reducing.In order to solve this problem, some scholars detect internal flaw fruit by half transmitting measurement, to avoid light intensity
Weaker problem.
The research that internal flaw apple is detected currently with transmission measurement is usually all detected using single-point, since inside lacks
Any position for being likely distributed in apple tissue is fallen into, single-point detection has significant limitation in accurate evaluation apple internal defect.
Summary of the invention
Being to provide one kind and capable of being detected to 360 ° of fruit using multiple channels for the purpose of this technology, improves detection
The contactless multi-path fruit Inner Defect Testing system of accuracy.
Contactless multi-path fruit Inner Defect Testing system described in this patent, including imaging spectrometer, light source control
System processed, detection platform;The light-source control system includes light source, focus lamp;The detection platform include coaxial land and
Hollow cylinder;The upper end of hollow cylinder passes through land bottom plate and is connected with land bottom plate, focuses in lower end and light-source control system
Mirror lens barrel is connected;Multiple fiber optic hubs are provided on land side wall;The imaging spectrometer is using multifiber as incident light transmission
Channel, one end of every optical fiber are inserted into the different jacks opened on land side wall, the other end with it is narrow in imaging spectrometer
Seam is opposite;
When to fruit internal defects detection, the light line focus mirror that light source issues is focused in land and in open circles
It on fruit above column, is incident on slit after fruit transmits by optical fiber, is obtained in reflection fruit by imaging spectrometer
The spectrum in each channel of portion's organization factors.
As an improvement, attaching black material in land inside sidewalls.In order to avoid reflection of the material to light of land itself,
Light absorption black material is sticked in land inner sidewall.
As an improvement, optical fiber is 6,6 corresponding jacks are uniformly distributed on land side wall.Optical fiber angle is 60 ° two-by-two,
To realize that 360 ° omni-directional detects fruit spectral information.
As an improvement, land plate upper surface has the counterbore coaxial with hollow cylinder.In order to guarantee that every optical fiber is each
Transmissivity obtained is consistent when acquiring reference spectrum, and reference cylindrical piece need to be placed on the counterbore position.
As an improvement, hollow cylinder is equipped with for adjusting with fixation hollow cylinder relative to focus lamp lens barrel axial position
Holding screw.It tightens holding screw, hollow cylinder and land to fix relative to focus lamp lens barrel axial position, unclamps clamp screw
Nail, axial location of the adjustable hollow cylinder relative to focus lamp lens barrel.
This technology has passed through a kind of multiple channels of use simultaneously and has detected to 360 ° of fruit, and with the flat of each channel spectrum
Equal spectrum carries out classification assessment to fruit internal defect, improves the contactless multi-path fruit internal flaw of the accuracy of detection
Detection system.
Fruit internal defect inspection method described in this patent, using above-mentioned contactless multi-path fruit internal flaw
Detection system, the light line focus mirror that light source issues are focused at placement and are located in land and on the fruit above hollow cylinder, warp
It is incident on slit after fruit transmission by optical fiber, each logical of reflection fruit internal organization factors is obtained by imaging spectrometer
The spectrum in road obtains averaged spectrum after carrying out the spectrum in each channel of tested fruit averagely, by the averaged spectrum of tested fruit
Being tested fruit internal with the averaged spectrum multilevel iudge of normal fruit whether there is defect.
As an improvement, the carpopodium and fruit calyx line of fruit are vertical with land axis.When fruit carpopodium and fruit calyx line with
When land axis is vertical, the accuracy of detection can be further improved.
Judge in tested fruit as an improvement, the averaged spectrum of tested fruit is established partial least squares discriminant analysis model
Portion whether there is defect.
This patent the utility model has the advantages that this technology optical fiber for being looped around fruit periphery using more are logical as incident light transmission
Road carries out contactless comprehensive half transmitting multi-channel detection to fruit, with the averaged spectrum in each channel and normal fruit
Averaged spectrum multilevel iudge, which is tested fruit internal, whether there is defect, improve the accuracy of detection.
By taking the detection to apple as an example.When detection, there are three types of apple placement locations.Detection orientation A: it is placed in land
Apple stem and fruit calyx line are in land axis parallel or overlapping positions, and carpopodium is under.Detection orientation B: it is placed on ring
Apple stem and fruit calyx line in platform are in land axis parallel or overlapping positions, and carpopodium is upper.Detection orientation C: it puts
Set apple stem in land and fruit calyx line be in land axis upright position, in other words, at carpopodium and fruit calyx line
In horizontal position.
Detection orientation A training set and test set in each channel be averaged classification accuracy be 90.0% and 88.1%, detection side
Position B is 89.9% and 86.6%, and detects that C each channel general classification performance in orientation is best, and training set and test set are averagely classified
Accuracy is in 92.0% and 90.9%.
Detect orientation C averaged spectrum establish PLSDA model regardless of in training set still in test set to the totality of apple
The equal highest of classification accuracy, respectively 97.3% and 93.1%, it is corresponding to be improved than detection orientation A averaged spectrum classification rate
4.6% and 1.7%, and compare detection orientation B averaged spectrum classification accuracy and improve 6.9% and 4.3%.
Detailed description of the invention
Fig. 1 is schematic diagram of the contactless multi-path fruit Inner Defect Testing system when detecting orientation A;
Fig. 2 is detection orientation B schematic diagram;
Fig. 3 is detection orientation C schematic diagram;
Fig. 4 is multichannel high light spectrum image-forming spectrometer schematic diagram;
Fig. 5 is the status diagram opposite with optical fiber of the slit in imaging spectrometer;
Fig. 6 is detection platform schematic diagram;
Fig. 7 is another schematic diagram of detection platform;
Fig. 8 is apple appearance diagram;
Fig. 9 is normal apple longitudinal profile;
Figure 10 is internal flaw apple longitudinal profile;
Figure 11 is the cross-sectional schematic diagram of internal flaw apple;
Figure 12 is the different channel spectrum figures of normal apple;
Figure 13 is the different channel spectrum figures of small defect apple;
Figure 14 is the different channel spectrum figures of big defect apple;
Figure 15 by channel 6 from detection orientation A obtain normal apple and defect apple average light spectrogram;
Figure 16 by channel 6 from detection orientation B obtain normal apple and defect apple average light spectrogram;
Figure 17 by channel 6 from detection orientation C obtain normal apple and defect apple average light spectrogram.
In figure, multichannel high light spectrum image-forming spectrometer 100, detection platform 200, light-source control system 300,
Optical fiber 1,2,3,4,5,6,33,34,35;
Land 21, hollow cylinder 22, fiber optic hub 23, black material 24, counterbore 25.
Focus lamp lens barrel 31,
Detect orientation A, B, C.
Specific embodiment
This patent is described in detail with reference to the accompanying drawing.
1 contactless multi-path fruit Inner Defect Testing system
Contactless comprehensive half transmitting multi-path fruit Inner Defect Testing system shown in Figure 1, by three parts
Composition, respectively light-source control system 300, multichannel high light spectrum image-forming spectrometer 100 and detection platform 200 form.
Detection platform 200 is mainly used for supporting sample, connecting multi-channel high light spectrum image-forming spectrometer and light-source control system.
The detection platform 200 includes coaxial land 21 and hollow cylinder 22.The upper end of hollow cylinder 22 pass through land bottom plate and with
Land bottom plate is connected, and lower end is connected with the focus lamp lens barrel 31 in light-source control system 300.The lower end of hollow cylinder is radially square
To being provided with for adjusting and holding screw (not shown) of the fixation hollow cylinder relative to focus lamp lens barrel axial position.Land
6 fiber optic hubs 23 are provided on side wall;Black material 24 is attached in land inside sidewalls.Land plate upper surface have with it is hollow
The coaxial counterbore 25 of cylinder.
In our current research, multichannel high light spectrum image-forming spectrometer is only as the flat of building spatially resolved spectroscopy detection system
Platform.Imaging spectrometer selection protrudes into formula aberration correction Grating Design, and entrance slit width is 25 μm, length 9mm, such as Fig. 5.Its
Camera selects the high-performance Vis-InGaAs detector of 229 × 320 pixels, covers 550-1650nm spectral region, spectrally resolved
Rate is 4.85nm, using 14 frame collectors.Collected light is focused on slit using object lens by conventional high light spectrum image-forming spectrometer
On, it is different from, it is 200 μm by 35 diameters that multichannel high light spectrum image-forming spectrometer, which uses up fine substitution object lens, numerical aperture
The reception optical fiber that diameter is 0.22 forms a line, and is placed on before slit, and such as Fig. 4,5 (this patent only uses 6 optical fiber 1- therein
6 are used as incident light transmission channel).After being obtained by optical fiber from light reflected in sample, it can focus on slit, pass through into
As spectrometer distributes it to different wavelength, then it is mapped in imaging spectrometer in the two-dimensional detector array of camera.
The six roots of sensation detection fiber of multichannel high light spectrum image-forming spectrometer is inserted into outer diameter 140mm, on internal diameter 130mm land outer wall
Six diameters be 3mm fiber optic hub in, wherein optical fiber head diameter is identical as fiber optic hub aperture, and optical fiber angle is 60 ° two-by-two,
To realize 360 ° omni-directional test sample spectral information.In order to avoid reflection of the aluminum alloy materials to light of land itself,
Land inside cylindrical walls stick light absorption black material.In addition, in order to be obtained when guaranteeing that every optical fiber acquires reference spectrum every time
The transmissivity obtained is consistent, and reference cylindrical piece need to be centrally disposed position, therefore, have 2mm, diameter 80mm at detection platform center
Counterbore.The lower half portion of detection platform be outer diameter is 70mm for connecting light-source control system, and internal diameter is hollow for 58mm's
Cylinder is directly installed on the focus lamp lens barrel of light-source control system, and on the open circles post jamb for being 70mm by outer diameter
Two tight fixed bolts adjust the height and position of detection platform.
The use quartz tungsten halogen lamp light-source control system of light-source control system 300 belongs to the prior art, including light source 31, general
The focus lamp 32 etc. that the light that light source issues is assembled.
2 materials and methods
2.1 apple samples
Freezer locker room is placed on about 5 months after experiment 430 apple samples harvest used.All apple samples are without any
External Defect, and appearance uniform is consistent, sees Fig. 8.Preceding rag is tested by apple wiped clean, after spectra collection, apple is cut
It opens, by visual observation, apple is divided into normal apple and internal flaw apple (internal brown stain), wherein normal apple 243,
Internal flaw apple 187, see Fig. 9-11.
2.2 spectra collection
As shown in Figure 1-3, apple sample is placed on detection platform center when acquisition sample spectra.In experiment, quartz
Halogen tungsten lamp light source control system power setting be 240W, via focus lamp from vertical direction direct irradiation on sample.In order to keep away
Reference cylindrical body is placed directly in the 2mm counterbore of detection platform when acquiring reference sample spectrum by test free fiber-optic signal saturation
In, the time for exposure of multichannel high light spectrum image-forming spectrometer is set as 15ms, and six roots of sensation detection fiber acquires reference cylindrical body cylinder
The transmissivity on surface is as reference spectrum.When acquiring sample spectra, the time for exposure setting of multichannel high light spectrum image-forming spectrometer
For 60ms, to guarantee that each detection fiber can get sufficiently strong signal.The dark field spectrum under two kinds of time for exposure is acquired respectively,
Spectrum correction for test specimen.Each sample places three different directions, respectively to detect orientation A (carpopodium and fruit calyx
Line is in vertical position, and carpopodium is under), it detects orientation B (carpopodium and fruit calyx line are in vertical position, and carpopodium is upper) and examines
Interception C (carpopodium and fruit calyx line are in a horizontal position) is indicated, acquires the spectrum of three different directions, for analyzing not Tongfang
Influence of the position to testing result.
2.3 spectral manipulations and modeling method
Six groups of sample spectras are corrected by following formula, to reduce the error of instrument itself.
Wherein SaAnd DaThe sample original spectrum and dark field spectrum respectively acquired under the 60ms time for exposure, RbAnd DbFor
The reference spectrum acquired under the 15ms time for exposure.Each channel spectrum is built respectively in different sample detection orientation (A, B and C)
Vertical partial least squares discriminant analysis (PLSDA) model.Then, same sample is detected to six samples of orientation (such as detection orientation A)
Product spectrum is average, obtains the spectral combination (i.e. averaged spectrum) in three different sample detections orientation.
430 consistent apples of appearance are randomized into the training set containing 300 samples and pre- containing 130 samples
Collection is surveyed, is sentenced using MATLAB R2016b combination PLS Toolbox 8.2 to establish the offset minimum binary of internal flaw apple identification
Not Fen Xi (PLSDA) model, with Venetian blind cross-validation method, and according to the error in classification average value of minimum cross validation
Or best latent variable quantity is determined with because subnumber increases classification results and do not improve.
3 results and discussion
3.1 spectrum analysis
Figure 12-14 shows normal apple, small defect apple (defect area is lower than 40%) and big defect apple (defect face
Product is greater than the SPECTRAL DIVERSITY in 40%) six channels.For normal apple and big defect apple, due to tissue relatively more uniform one
It causes, therefore, six channels show more consistent spectral shape, but still can find, there are smaller differences for each interchannel, such as scheme
Shown in 12.
And the detection for small defect apple, since defective locations are unevenly distributed, the collected spectrum in channel is possible to
It is the light that normal tissue transmits, it is also possible to be the light that defect(ive) structure transmits, as shown in figure 13, channel 1,2 and 6 is adopted
The spectrum of collection is similar to normal apple spectrum, and remaining 3 channel spectrum is similar to defect apple averaged spectrum in Figure 15, this says
Bright single-point detection is difficult accurate evaluation internal flaw apple, also illustrates from another point of view, contactless comprehensive half transmitting multi-pass
Superiority of the road bloom spectra system in detection internal flaw apple.For big defect apple, as shown in figure 14, the light in six channels
Spectral shape is but obvious with normal apple spectral shape difference than more consistent, illustrates normal apple and big defect apple in Spectral Properties
It is relatively easy to distinguish in sign.
According to Figure 15-17 it is found that be between normal apple and the averaged spectrum of defect apple it is discrepant, in 600nm,
It is especially apparent at tetra- wave crests of 700nm, 800nm and 1060nm.Light and apple sample interact by scattering and absorption etc., then
It is reflected into detection fiber, reflectivity is related to the structure of apple sample and chemical component.Someone once reported that the scattering of light was depended on
Cell size and intracellular matrix in sample tissue.The tissue color of normal apple is more vivid, and apple is defective
Tissue color is deeper, brown stain occurs, so that light absorption becomes apparent from, therefore, the spectral reflectivity of internal flaw apple is than normal apple
Fruit it is low.Have been also found that there is trough, respectively Chlorophyll absorption peak and moisture absorption peak at 675nm and 750nm from figure.
Since the chlorophyll content of the apple itself is lower, normal apple and internal flaw apple difference are unobvious at 675nm.
The structural constituent and cell of internal flaw apple change or destroy, the destruction of cell may release more moisture and
Its moisture absorption peak is caused to become apparent from than normal apple.Also it can be observed from Figure 15-17, the different detection position of apple is obtained
The spectrum obtained is also different, wherein the SPECTRAL DIVERSITY of normal apple and internal flaw apple is more significant, says in detection orientation C
It is bright when carrying out apple detection, more accurate testing result may be obtained using suitable detection orientation.
3.2 are based on single pass apple internal defect Classification and Identification
As shown in Table 1, the classification results in same detection orientation, different channels are different, such as in detection orientation A,
Channel 2 is up to 90% to the classification accuracy of test set defect apple, and channel 6 and 4 is respectively to detect orientation B and C most
Good single channel, classification accuracy are respectively 88.5% and 92.3%.When due to spectral detection, apple internal defect group can not be determined
The specific orientation knitted, this may be the main reason for causing each channel classification results difference, this also illustrates from another point of view, single-point
There is certain limitation in the assessment of internal flaw apple in detection method.
The detection orientation it is found that different is further looked at, the general classification performance in each channel is also different, detects orientation
In A training set and test set each channel be averaged classification accuracy be 90.0% and 88.1%, detection orientation B be 89.9% He
86.6%, and detect that C each channel general classification performance in orientation is best, and training set and test set are averaged classification accuracy 92.0%
With 90.9%.In addition, it is also seen that, being detected in orientation C, the average light spectral difference of normal apple and internal flaw apple from Figure 12
Different maximum, this can also explain that detection orientation C can obtain more preferably classification accuracy from another point of view.
These results suggest that when to sample detection, the suitable assessment for detecting orientation and being more advantageous to internal flaw apple.
Each channel in each detection orientation is combined, the spectroscopic data in average 6 channels, hair by further analysis
It now can further promote classification accuracy, and the average rear spectrum best single channel in detection orientation more corresponding than its point of combination of channels
Class result is good.This illustrates that multichannel detection system has bigger potentiality in assessment internal flaw apple.
As can be known from Table 1, detection orientation C averaged spectrum establish PLSDA model regardless of in training set still in test set
To the equal highest of the classification accuracy of defect apple, respectively 97.3% and 93.1%, it is corresponding than detection orientation A averaged spectrum classification
Rate improves 4.6% and 1.7%, and compares detection orientation B averaged spectrum classification accuracy and improve 6.9% and 4.3%.
Each channel be averaged classification accuracy refer to be respectively adopted with each channel (the present embodiment is 6 channels) spectrum it is partially minimum
Two, which multiply recurrence, establishes discriminant analysis model, judges tested fruit internal with the presence or absence of the average value of the accuracy of defect;Rather than
Averaged spectrum is obtained after the spectrum in each channel is carried out averagely, discriminant analysis is established using Partial Least Squares Regression with averaged spectrum
Model judges that tested fruit internal whether there is the accuracy of defect.
Apple population of samples classification accuracy of the table 1 based on PLSDA model
The 3.3 apple internal defect Classification and Identifications based on combination channel
Each detection orientation combination channel averaged spectrum of table 2 further detailed analysis divides normal apple and defect apple
Class accuracy.It can be seen that either training set or test set, PLSDA model are above the classification accuracy of normal apple
Internal flaw apple.The tissue of normal apple is relatively consistent, and tissue density is also relatively more unified, therefore, with higher
Classification accuracy, and have the apple of internal flaw that may only have portion of tissue to be destroyed or brown stain, remaining tissue and normal apple
More close, detector is just easy to be sentenced mistake when acquiring spectrum.
In training set, the classification accuracy of the normal apple of detection orientation C and internal flaw apple is more consistent, 90% with
On, and it is not high to the classification accuracy of internal flaw apple to detect orientation A and B, 87% or so, but the classification to normal apple
Accuracy and detection range C still have comparativity.
In test set, detection orientation C is 95.7% and 90% to the classification accuracy of normal apple and internal flaw apple,
And be above other two detection orientation as a result, can will test the normal apple classification accuracy rate of orientation A improves 3.0%, detection
The normal apple of orientation B and internal flaw apple classification accuracy rate improve 4.7% and 3.8%.Orientation B is detected to show in three orientation
Show poor classification results, the especially classification to internal flaw apple, there are 8 samples to sentence mistake in 60 samples, classification is accurate
Rate only has 86.7%.
Table 2 is based on detection orientation A, the PLSDA category of model accuracy rate that B and C averaged spectrum is established
Note: 173:173 normal apple samples (training set);127:127 internal flaw apple sample (training set);
70:70 normal apple samples (test set);60:60 internal flaw apple sample (test set)
This patent is a kind of comprehensive half transmitting multichannel detection system of novel non-contact, is lacked using the system to inside
It falls into apple and carries out classification and Detection, assess each channel by establishing PLSDA model, each orientation and combination of channels of detecting is to inside
The classifying quality of defect apple.
(1) for same detection orientation, since internal flaw Tissue distribution is uneven, the classification results in 6 channels are respectively not
Identical, this shows to be not easy to reach high detection accuracy based on conventional single channel detection methods.
(2) based on three different detection orientation, the whole classification accuracy that each channel obtains is different, detects orientation C
Obtain more excellent classification results.Therefore, accurate to reach high detection in practical application it is necessary to consider the detection orientation of apple
Rate.
(3) it can further improve the classification of internal flaw apple using the PLSDA model that the averaged spectrum in 6 channels is established
Accuracy rate, detection side coil C are respectively 95.7% and 90.0% to the classification accuracy of normal apple and internal flaw apple.
(4) on the whole, PLSDA model is better than internal flaw apple to the identification of normal apple.