NZ762809B2 - Classification method and apparatus - Google Patents

Abstract

There is provided a method for object classification, the method comprising the steps of: guiding (S1) a continuous stream of objects (4) from a transport mechanism (2) directly into an unsupported path (6), along which said object stream (6) is fed through a detection region (12); illuminating (S2) said detection region (12) with a radiation band in a first direction (10); optically scanning (S3) said detection region (12) to detect electromagnetic radiation reflected by the at least one object in the detection region (12) by viewing said detection region along a second direction (16), wherein the first direction (10) and the second direction (16) have a cross-section in the detection region (12) and forms an angle relative each other within the range of 10° - 80°; analyzing (S4) the information from the optical scanning; and classifying (S5) objects from the object stream in at least two different directions based on the analysis of the transparency information from the optical scanning; wherein the step of analyzing the information from the optical scanning comprises analyzing the objects based on the intensity, spread and texture of the detected radiation from the optical scanning. said detection region (12) with a radiation band in a first direction (10); optically scanning (S3) said detection region (12) to detect electromagnetic radiation reflected by the at least one object in the detection region (12) by viewing said detection region along a second direction (16), wherein the first direction (10) and the second direction (16) have a cross-section in the detection region (12) and forms an angle relative each other within the range of 10° - 80°; analyzing (S4) the information from the optical scanning; and classifying (S5) objects from the object stream in at least two different directions based on the analysis of the transparency information from the optical scanning; wherein the step of analyzing the information from the optical scanning comprises analyzing the objects based on the intensity, spread and texture of the detected radiation from the optical scanning.

Description

CLASSIFICATION METHOD AND APPARATUS TECHNICAL FIELD OF THE INVENTION The invention relates to the field of object classification. More precisely, the invention relates to a method and an apparatus for off-belt object classification.

BACKGROUND OF THE INVENTION Machines for inspection and sorting of bulk objects supplied in a continuous stream typically comprise a feed unit, an optical system and an analysis unit. The feed unit supplies a stream of objects which are to be inspected continuously through a detection region that is scanned by the optical system, which is in operational communication with the analysis unit.

The analysis unit analyzes each separate object in the object stream for one or more preselected properties, such as color, shape and/or texture or any combination thereof. Based on this analysis, the analysis unit can examine whether the inspected object satisfies specific criteria in terms of the observed property, resulting in a classification.

A requirement for such inspection and sorting apparatuses based on an optical sensor and an analysis device is that a correct distinction can be 2O made n optical information coming from the inspected objects and optical ation coming from the background. describes an apparatus for inspection of objects, provided with a transport mechanism, for instance a conveyor belt or a chute, configured to transport a continuous stream of objects so that, on g the transport mechanism, the object stream follows a all path along which it is fed in a single object layer through a detection region, a radiation source configured to illuminate the detection region, a detection unit, ured to optically scan the illuminated ion region, an analysis unit and possibly a l unit and also a background t, which is situated behind the falling object , seen from the position of the detection unit, positioned so that electromagnetic radiation beams from the radiation source impinge on an illumination zone of the background element when these beams do not impinge on an object from the object stream, the detection unit can only receive an image of a detection zone of the background t, characterized in that the ound element is mounted so that the illumination zone and the detection zone are separated from each other.

The apparatus provides a solution for detection of products in a product stream without false detection of products from electromagnetic radiation reflected by the background, however it does not provide sorting of products based on optical characteristics and is not optimal for detecting dark products in the product stream.

SUMMARY OF THE INVENTION It is an object of the invention to provide an ed solution for off- belt object classification of transparent objects in a product stream.

According to a first aspect of the invention, this and other objects are achieved by a method for object classification, the method sing the steps of: g a continuous stream of objects from a transport mechanism ly into an unsupported path, along which the object stream is fed through a detection region; emitting electromagnetic radiation along a first direction for illuminating said detection region, which emitted electromagnetic radiation forms a radiation band extending in a direction orthogonal to said first direction; lly scanning the detection region to detect electromagnetic radiation reflected by the at least one object in the detection region by viewing the detection region along a second direction, wherein the first direction and the second direction have a cross-section in the detection region and forms an angle ve each other within the range of 3° - 80° or ° - 80°; analyzing the information from the l scanning; and classifying objects from the object stream based on the analysis of the transparency information or the reflection information from the l scanning; wherein the step of analyzing the information from the optical scanning comprises analyzing the objects based on the intensity, spread and ally texture of W0 2019;043231 the detected radiation from the optical scanning, and wherein the step of analyzing the information from the optical ng comprises comparing the information to ation in a lookup table and/or comparing the information to one or more thresholds.

According to one embodiment, said step of classifying said objects further comprises sorting the objects from the object stream in at least two ent direction based on the analysis of the reflection information from the optical scanning and/or based on classification data. ing to one embodiment, said step of analyzing the information from the optical scanning further comprises comparing electromagnetic radiation from the nation that is directly reflected by the at least one object in the object stream to information in a lookup table and/or to one or more thresholds to determine transparency or reflection information of said at least one object.

According to one embodiment, said step of analyzing the information from the optical scanning further comprises comparing ity and spread of electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to information in a lookup table and/or to one or more thresholds to determine transparency or reflection information of said at least one object.

According to a second aspect of the invention there is provided a method for object sorting, the method sing the steps of: guiding a uous stream of objects from a transport mechanism directly into an unsupported path, along which the object stream is fed through a detection region; emitting electromagnetic radiation along a first direction for illuminating said detection region, which d electromagnetic radiation forms a radiation band ing in a direction orthogonal to said first direction; optically ng the detection region to detect electromagnetic radiation reflected by the at least one object in the detection region by viewing the detection region along a second direction, wherein the first direction and the second direction have a cross-section in the detection region and forms an angle relative each other within the range of 3° - 80° or 10° - 80°; W0 2019;043231 analyzing the information from the optical scanning; and sorting objects from the object stream in at least two ent directions based on the analysis of the transparency information or reflection information from the optical scanning; wherein the step of analyzing the information from the optical scanning comprises analyzing the objects based on the intensity, spread and ally e of the detected radiation from the optical scanning.

The below information, features and embodiments relate to both the first and second aspect of the invention.

In relation to the invention the radiation source is a line illumination, i.e. the illumination forms a radiation band or a line when falling upon a flat surface which radiation band may be captured and viewed at least via an image senor. Further, the emitted electromagnetic radiation forms a radiation band when falling upon a flat surface which radiation band may be captured and viewed at least via an image senor. The illumination may be collimated or focused.

According to one example the measuring system ses of a radiation source and a or, ably d on the object plane. The detector measurement plane and the line illumination are disjoint and have a cross-section in the object plane. This means that if no object is present in the , an extremely low radiation is detected by the detector, since the illumination line and the detection line do not ect in the void space.

The step of analyzing the information from the optical scanning may further comprise determining arency information by comparing electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to a first threshold to determine that there is material present in the detection , and thereafter comparing electromagnetic radiation from the illumination that is directly reflected by the at least one object to a second threshold to determine if the present material is transparent and/or reflective, wherein the second threshold lies above the first threshold, and thereafter setting the transparency information.

By using threshold levels to evaluate whether objects are present in the detection region and determining a probability of the object being W0 2019;043231 transparent an efficient classification and/or sorting of s in for instance glass detection applications and other applications for classification and/or sorting of arent objects can be ed.

In relation to this invention, the term classification data refers to the data obtained in, or resulting from, the step of classifying objects in the object stream. One e of classification data is a specific class, like acceptable/non-acceptable; or a classification value within a certain range (e.g. class A is x1 to x2; class B is x2 to x3, where xi is a number), which classification value may be formed based on one single or a combination of measured parameter values. Another example of classification data is the fication value (formed based on one single or a combination of measured parameter values); the classification value may be a single value or an array of values.

According to one embodiment, the classification data (i.e. the data obtained in, or ing from, the step of classifying objects in the object stream) is used for sorting individual objects of a product stream in at least two different directions, additionally or alternatively the classification data can be used in the same apparatus or transferred to another device in order to perform various operations, such as sorting in later stages, as well as for statistical analysis. In other words, individual classification data may be assigned to dual objects and keep being linked to this object through various steps in the material handling s, and is optionally used at one or more stations in the material handling process. Additionally, or alternatively, dual or bulks of classification data may be processed for statistical purposes in the same machine where it was determined, or in another device to which it has been provided e.g. by wire or wirelessly.

Additionally or alternatively, the step ing the information from the optical scanning further includes fying to which degree said material is transparent. Additionally or alternatively, the step analyzing the ation from the optical scanning further includes classifying to which degree said material is reflective. The step of analyzing the information from the optical W0 2019;043231 scanning may further comprise comparing ly reflected to a third threshold to determine a ility of the present material being transparent.

The step of analyzing the information from the optical scanning may further comprise determining the height, and/or height profiles of objects in the object stream.

The step of analyzing the information from the optical scanning may comprise comparing the information to information in a lookup table (LUT) and/or comparing the ation to thresholds. The lookup tables maybe a one-dimensional lookup table or a mensional lookup table or a N- dimensional lookup table. By dimension here it is meant that the lookup table evaluates a sampled representation of a e.g. N variables. The one- dimensional lookup table returns an output in response to only one input parameter, the input parameter being e.g. the intensity or the spread of the detected radiation; i.e. one output is returned for LUT (Intensity) and one output is ed for LUT (Spread). The two-dimensional lookup table on the other hand returns an output in response to two input parameters, e.g. the intensity and the spread of the detected radiation, one output is returned for LUT (Intensity, Spread).

Alternatively, step of analyzing the information from the optical scanning may comprise the use of deep learning or support vector machines.

The method may further comprise a step of optically scanning a zone on a background element where the line illumination hits the background element, wherein the step of analyzing the information from the optical scanning comprises determining whether material is present in the detection region based on the ation from the optical scanning of the zone on the background.

Optically scanning the zone on the background element enables for ion of a line illumination reflection on the background element, which enables determination of whether there is an object t in the detection region based on the tion from the background element, thus ng to detect and sort even very dark objects in the object stream as well as to distinguish optically dark objects from optically transparent objects.

W0 2019;043231 The steps of lly scanning the zone on the background element and optically scanning the detection region may be performed simultaneously with one camera.

Using one camera with a field of view that covers both the ion region and the zone on the ound element where the laser line impinges the background element is a cost-effective solution that also simplifies the analysis of the information from the scanning.

The step of illuminating the detection region may be done with a plurality of line illuminations for a plurality of detection s and the step of optically scanning the detection region is done in a plurality of measurement lines for the detection regions. The step of analyzing the information from the l scanning may then comprise determining the motion of the objects in the object stream.

By ining the trajectory of the objects in the object stream more e ejection of the object may be performed, and a better overall classification and/or sorting can be achieved.

The plurality of line illuminations may have different wavelengths, wherein the step of ing the information from the optical ng comprises determining optical properties and physical properties of the objects in the object stream.

Alternatively or additionally, the plurality of line illuminations may have different zations. This may be beneficial for removing background radiation.

According to a third aspect of the invention, there is provided an apparatus for object classification and/or sorting, the apparatus comprising: a transport mechanism ed to transport an object stream so that the object stream, after leaving the transport mechanism, follows an unsupported path, along which it is fed through a detection region; a radiation source being ured to emit a radiation band in a first direction for illuminating the detection region; a detection unit arranged to view the detection region along a second direction and to detect electromagnetic radiation reflected by the at least one object in the detection region; wherein the first direction and the W0 2019;043231 second direction have a cross-section in the detection region and forms an angle relative each other within the range of 10° - 80°; an is unit in operational connection with the detection unit and ed to determine transparency information by comparing electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to a lookup table or to one or more thresholds to determine that there is material t in the detection region, and thereafter comparing electromagnetic radiation from the illumination that is ly reflected by the at least one object to a second threshold to determine if the present material is arent, wherein the second threshold According to a fourth aspect of the invention, there is provided an apparatus for object classification and/or sorting, the tus sing: a transport mechanism arranged to transport an object stream so that the object stream, after leaving the transport mechanism, follows an unsupported path, along which it is fed through a detection region; a radiation source being configured to emit a radiation band in a first direction for illuminating the ion region; a detection unit arranged to view the detection region along a second direction and to detect electromagnetic radiation reflected by the at least one object in the detection region; wherein the first direction and the second direction have a cross-section in the detection region and forms an angle relative each other within the range of 3° - 80° or 10° - 80°; an analysis unit in operational connection with the detection unit and arranged to determine transparency and/or tion information by comparing electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to at least one threshold or look-up table to determine if the material present in the detection region is transparent and thereafter setting the arency or reflection information.

The detection unit may be further ured to sense electromagnetic radiation ted by a point on a background element where the electromagnetic radiation from the radiation source impinges the background element.

W0 43231 The apparatus may comprise a plurality of radiation sources configured to illuminate objects in the object stream in a plurality of positions along the unsupported path.

The apparatus may further comprise a l unit configured to remove s from the object stream, wherein the removal of objects is based on the analysis in the analysis unit.

According to at least one embodiment the analysis unit is r arranged to determine transparency information by comparing electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to a first old or look-up table to determine that there is material present in the detection region, and thereafter comparing electromagnetic radiation from the nation that is directly reflected by said at least one object to a second threshold or a second look- up table to determine if the present al is transparent, wherein the second threshold optionally lies above the first threshold, and thereafter setting the transparency information.

It is noted that the invention s to all possible combinations of features in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described in more detail with nce to the appended gs, showing currently preferred embodiments of the invention.

Fig. 1 is a schematic perspective view of an apparatus according to an embodiment of the invention.

Fig. 2 is a schematic view of an apparatus according to another embodiment of the invention, comprising three line illuminations.

Fig. 3 is a schematic perspective view of an apparatus according to another embodiment of the invention, comprising line illumination detection.

Fig. 4 is a flow chart of the method according to an embodiment of the invention.

W0 2019;043231 Fig. 5 is a plot of the electromagnetic radiation detected by a detector in an apparatus according to an embodiment of the invention.

Fig. 6 is a tic view of determination of the trajectory of an object in the object stream, which can be used with the apparatus of Fig. 2.

Fig. 7 is a schematic view of a cross-section of the electromagnetic radiation detected by a or in an apparatus according to Fig. 3.

As illustrated in the figures, the sizes of layers and regions may be rated for rative purposes and, thus, may be provided to illustrate the general structures of embodiments of the present invention. Like nce numerals refer to like elements hout.

ED DESCRIPTION OF THE INVENTION Fig. 1 shows an apparatus for inspection of objects in an object stream according to an embodiment of the invention. A conveyor belt 2 guides an object stream 4 into an unsupported path, here a free-fall path 6. Although a conveyor belt 2 is here used for guiding the object stream 4 to the free-fall path 6, any type of transport mechanism, such as chutes or similar, can be used according to the invention. A radiation source, here a line laser 8, illuminates a laser line 10 in a first direction 10 through a detection region 12.

Although a laser line is here used, any type of radiation source which uses focused electromagnetic ion can be used according to the invention.

The detection region 12 is a region through which the objects travel after having left the or belt 2, when being in a free-fall path 6. The laser line may be of substantially equal width as the conveyor belt 2 from which the object stream 4 is guided into the free-fall path 6, to ensure that all s in the object stream 4 travel through the detection region 12. A detector, here a camera 14, detects radiation in a measurement plane 16 that intersects the laser line in the detection region 12. The measurement plane 16 may be of substantially equal width as the laser line 10.

The first direction 10 and the second direction 16 are disjoint and have a cross-section in the detection region 12. The detection region 12 is off-belt and at a position where the object stream 4 discharged from the conveyor belt W0 2019;043231 2 is in a free-fall path 6. If there is no object present in the detection region 12 the laser line will impinge a part of a background element that is not detected by the part of the measurement plane that travel through the detection region.

Hence, there will be no reflected omagnetic radiation detected if no object is present, which enables for distinct recognition whether there is an object present in the detection .

The angle n the first direction 10 and the second ion 16 is preferable within the range of 3° - 80°, more preferably within the range of 5° - 60°, more preferably within the range of 8° - 40°, more preferably within the range of 10° - 35°, more preferably within the range of 15° - 30°, most preferably within the range of 20° - 25°.

The wavelength of the emitted electromagnetic radiation is preferably within the range of 300 nm — 2000 nm, more preferably within the range of 400 nm - 700 nm.

Determination of material properties of the objects in the object stream is done based on the ly reflected electromagnetic ion at the surface of the objects, the diffusely reflected electromagnetic radiation from the objects and/or the height of the objects. Thresholds can be used to determine optical properties of the objects. Referring to Fig. 5, the directly reflected electromagnetic radiation can be seen as the intensity at the maximum in y-direction, the diffusely reflected omagnetic radiation can be seen as the line width around the maximum in y-direction and the height can be seen as the maximum in y-direction. Determination of the height is beneficial when it comes to calculation of the trajectory of the objects in the object stream.

The analysis of information from the optical scanning may also comprise identifying and analyzing several surfaces of transparent objects in the object stream, based on double surfaces as seen in Fig. 5.

According to one embodiment of the invention, determination of the transparency of the objects in the object stream is achieved by ing the directly reflected electromagnetic radiation to threshold values. A first threshold value is then used to determine if an object is t if the directly W0 2019;043231 reflected electromagnetic radiation exceeds the first threshold value. A second threshold value, higher than the first threshold value, is then used to ine that the object is transparent if the directly reflected electromagnetic radiation does not exceed the second threshold value.

Several such thresholds can be applied to determine probabilities of the object being transparent. Combinations of thresholds for the ent parameters, that is the directly reflected electromagnetic radiation at the surface of the objects, the diffusely reflected electromagnetic radiation from the objects and/or the height of the objects, to determine various optical properties of the objects can be applied.

Alternatively, or additionally to the threshold ination, lookup tables, deep learning and/or support vector machines can be used to determine ties of the objects.

In order to remove ambient electromagnetic radiation in the analysis of the detected electromagnetic radiation, a frame with the laser on and a frame with the laser of may be recorded. A ound subtraction is then performed in the is to get rid of the ambient electromagnetic radiation.

Pulsing of the laser using a beam splitter may also be used for this purpose.

The tus may further comprise a removal unit, such as an air blower, configured to remove objects that are rejected in the analysis and thus sort objects based on the is.

The apparatus may additionally include a bandpass filter on the or, polarized electromagnetic radiation or polarization filter in front of the detector.

The apparatus may also be using a d 3D detection with polygon mirror or can be used in combinations with other detectors.

Fig. 2 shows an apparatus similar to that in Fig. 1 but comprising a plurality of parallel line illuminations 8, set up to create a plurality of parallel laser lines. This s for one, as in this case, or several cameras 14 to detect reflected electromagnetic radiation from the plurality of parallel line laser lines in a plurality of detection regions 12 at different ons in the free-fall path 6 of the object stream 4. In this way, the positions of the objects W0 43231 in the different detection regions 12 can be determined, to determine a motion, or tory, of the objects in the object stream 4. ln sorting systems, the object speed and moving direction is normally assumed to be constant in-between detection and ejection and if objects move with non-constant speed, there is a risk for unprecise removal of rejected objects. In some situations, the on window is increased in order to compensate the variation in movement. This leads to a stable ejection, but also an increase of unwanted removal of objects from the object stream 4.

An alternative to all of the detection zones being in the free-fall path of the object stream is that one or more of them being in the object stream on the conveyor belt, prior to being in a free-fall path.

The m distance between detection and ejection is determined by pixel size and y. For systems with big pixel sizes the minimum distance between detection and on can be quite large. If two detectors are combined, the movement of objects reduces the performance of convergence algorithms and thus also the ejection performance. By determining the trajectory of the objects in the object stream more e ejection of the object may be performed, and a better overall sorting can be achieved.

Alternatively, or complementary to using the classification data for sorting as bed above, the data from the classification step can be used in the same apparatus or transferred to another device in order to do various operations, such as sorting, in later stages, as well as for statistical analysis.

Fig. 6 shows a motion estimation of an object performed by an tus according to Fig. 2. Two high resolution detectors A, C are responsible for movement estimation of the object while a low resolution detector B is sible for al classification of the object. The detected objects of the first high resolution detector A are ed and mapped to correspondent objects in the second high resolution detector C. Based on the correspondent positions of the object in the first and the second high resolution detector A, C the position of the object is interpolated for the low resolution detector B and for a blow bar D. The sensor data of the low W0 2019;043231 resolution detector B is combined into the interpolated image on. The blow bar D uses an interpolated position for ejection. The position of the first and second high resolution detectors A, C is disjoint, while the low resolution detector B can be mounted here. The interpolated position reduces error for ejection and convergence for rolling objects.

The tus may also comprise several lasers of different wavelength, which s for determination of further optical properties such as the color of the objects and analysis of other parameters based on spectroscopy. Lasers at different ons, such as in Fig. 2, can be used for this purpose, but also multiple pulsed lasers at the same optical plane is a possibility.

The apparatus may also combine different laser polarizations to filter portions of the reflected electromagnetic radiation and more easily distinguish properties of the objects in the object stream. The apparatus may for instance comprise several lasers with different polarizations or a polarization camera.

Fig. 3 shows an apparatus for object inspection similar to that in Fig. 1.

However, the tus has in this embodiment a camera 14 that detects radiation in an area that covers both the detection region 12 and a zone 22 where the line illumination impinges a background element 24. This enables for the camera 14 to detect a line illumination reflection on the background element 24, which enables determination of whether there is an object present in the detection region 12 based on the reflection from the background element 24. This is l when it comes to detecting objects that exhibit very low reflection . A single camera 14 here covers both the detection region 12 and the zone 22 on the background element 24, however two different detectors can also be used for these es according to the ion.

Fig. 7 shows a schematic view of the electromagnetic radiation detected by the detector in the apparatus of Fig. 3. The object signal will be present when there is an object in the detection region that reflects the electromagnetic radiation emitted by the laser line, while the background signal can r be used to determine if there is a very dark, that is W0 2019;043231 essentially non-reflective, object in the detection region. The background signal, being the electromagnetic radiation emitted by the laser line and reflected by the background element, can also be used as a way of calibrating the laser line against the dark zone for background reference.

The laser line reflected by the background element can also be used to ine if an object in the object stream is transparent, since a transparent object will give rise to transmission of part of the emitted electromagnetic radiation while an opaque object will not enable any transmission of the emitted electromagnetic radiation.

Fig. 4 is a flow chart of a method of a method for inspection of objects, comprising the steps of: guiding 81 a uous stream of objects 4 into a free-fall path 6, along which the object stream 4 is fed in a single object layer through a detection region 12; illuminating 82 the detection region 12 in an first direction 10; optically scanning 83 the detection region 12 in a second direction 16; and analyzing 84 the information from the optical scanning; n the measurement plane 12 and the first direction 10 are disjoint and have a cross-section in the ion region 12.

Possible applications for the method and apparatus range over, but are not limited to, classification and/or g of glass, foil, napkins, printed circuit , cartridges, mining material, as well as quality analysis of food with regards to size and ion of cracks or foreign material. It can also be used to identify polymers in a waste stream.

The person skilled in the art realizes that the t invention by no means is limited to the embodiments bed above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For e, the radiation source and detector can be arranged in any direction that still allows for the method to be carried out according to the invention.

Additionally, variations to the disclosed embodiments can be understood and affected by the skilled person in cing the claimed invention, from a study of the drawings, the disclosure and the appended W0 2019;043231 claims. In the claims, the word “comprising” does not exclude other ts or steps, and the indefinite article “a” or “an” does not exclude a plurality.

ITEMIZED LIST OF EXEMPLIFYING EMBODIMENTS IEE1. A method for object classification, the method comprising the steps of: - guiding a continuous stream of objects from a transport mechanism directly into an unsupported path, along which said object stream is fed through a detection region; - emitting electromagnetic radiation along a first direction for illuminating said ion region, which emitted electromagnetic radiation forms a radiation band extending in a direction orthogonal to said first direction; - optically scanning said detection region to detect electromagnetic radiation reflected by the at least one object in the detection region by viewing said detection region along a second direction, wherein the first direction and the second direction have a cross- section in the detection region and forms an angle relative each other within the range of 3° - 80°; - analyzing the information from the l scanning; and - classifying objects from the object stream based on the analysis of the reflection ation from the optical scanning; n the step of analyzing the information from the optical scanning comprises ing the s based on the intensity and spread of the detected radiation from the optical scanning.

IEE2. The method according to IEE1, wherein said step of classifying said object r comprising sorting the objects from the object stream in at least two different directions based on the analysis of the reflection information from the optical scanning.

W0 2019;043231 IEE3. The method ing to any of the preceding lEEs, wherein the step of analyzing the information from the optical scanning comprises determining tion information by comparing electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to a first threshold, and thereafter comparing electromagnetic radiation from the illumination that is directly reflected by said at least one object to a second threshold to determine transparency of said at least one object, wherein the second threshold lies above the first threshold, and thereafter setting the reflection information.

IEE4. The method according to any of the preceding lEEs, wherein the step of analyzing the ation from the l scanning further comprises determining height profiles of objects in the object stream.

IEE5. The method according to any of the preceding lEEs, wherein the step of analyzing the ation from the optical scanning comprises comparing the information to information in a lookup table and/or comparing the information to thresholds.

IEE6. The method according to any of the preceding lEEs, n the step of analyzing the information from the optical scanning comprises the use of deep learning or support vector es.

IEE7. The method according to any of the preceding lEEs, further comprising a step of lly scanning a zone on a background element where the line illumination hits said background element, wherein the step of analyzing the information from the optical scanning comprises ining whether material is present in the detection region based on the information from the optical scanning of the zone on the background.

W0 2019;043231 |EE8. The method according to IEE 7, wherein the steps of optically scanning the zone on the background element and optically scanning the detection region are performed simultaneously with one camera.

|EE9. The method according to any of the preceding |EEs, where the step of illuminating said detection region with electromagnetic radiation is done with a plurality of line illuminations for a ity of detection regions and the step of optically ng said detection region is done in a plurality of measurement lines for said detection regions.

|EE10. The method ing to IEE 9, wherein the step of analyzing the information from the optical scanning comprises determining the motion of the objects in the object .

|EE11. The method according to |EEs 9 or 10, wherein the plurality of line illuminations have different wavelengths, wherein the step of analyzing the information from the optical scanning comprises determining optical ties and physical ties of the objects in the object stream.

|EE12. The method according to any of |EEs 9-11, wherein the plurality of line nations have different polarizations.

|EE13. An apparatus for object classification, the apparatus comprising: - a transport mechanism arranged to transport an object stream so that said object stream, after leaving the transport mechanism, follows an orted path, along which it is fed through a detection region; - a radiation source being configured to emit electromagnetic ion in a first direction for illuminating the detection region, which radiation source is configured to generate a line illumination; W0 43231 - a detection unit arranged to view said detection region along a second direction and to detect electromagnetic radiation reflected by the at least one object in the detection region, wherein the first direction and the second direction have a cross- section in the detection region and forms an angle relative each other within the range of 10° - 80°; - an analysis unit in operational connection with the detection unit and arranged to determine transparency information by comparing electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to a first old to determine that there is material present in the detection region, and thereafter ing electromagnetic radiation from the illumination that is directly reflected by said at least one object to a second threshold to determine if the present material is transparent, n the second threshold lies above the first threshold, and thereafter setting the transparency information; and - a l unit configured to remove objects from the object stream (4), n said removal of objects is based on the analysis in the analysis unit.

IEE14. The apparatus according to IEE 13, n the detection unit is further configured to sense electromagnetic radiation reflected by a point on a background element where the electromagnetic radiation from the radiation source impinges said background element.

IEE15. The apparatus according to IEE 13, comprising a plurality of radiation s configured to illuminate objects in the object stream in a plurality of positions along the unsupported path.

C L A I M S 1. A method for object classification, the method comprising the steps of: - guiding (S1) a continuous stream of objects (4) from a transport mechanism (2) directly into an unsupported path (6), along which said object stream (6) is fed through a detection region (12); - emitting electromagnetic radiation along a first direction (10) for illuminating (S2) said detection region (12), which emitted electromagnetic radiation forms a radiation band extending in a direction orthogonal to said first direction; - lly ng (S3) said detection region (12) to detect electromagnetic radiation reflected by the at least one object in the detection region (12) by viewing said detection region along a second direction (16), wherein the first direction (10) and the second direction (16) have a crosssection in the detection region (12) and forms an angle relative each other within the range of 3° - 80°; - analyzing (S4) the information from the optical scanning; and - fying (S5) objects from the object stream based on the analysis of the reflection information from the optical scanning; wherein the step of analyzing the information from the optical scanning comprises analyzing the objects based on the intensity and spread of the detected radiation from the optical scanning and wherein the step of ing the information from the optical scanning comprises comparing the information to information in a lookup table and/or comparing the information to thresholds. 2. The method according to claim 1, wherein said step of fying said object further comprising sorting the objects from the object stream in at least two ent directions based on the analysis of the reflection information from the optical scanning. 3. The method according to any of the preceding claims, n the step of analyzing the information from the optical scanning further comprises comparing the electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to ation in a lookup table and/or to one or more thresholds to determine transparency or reflection information of said at least one object. 4. The method according to any of the preceding claims, wherein the step of analyzing the information from the optical scanning comprises determining reflection information by comparing electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to a first threshold, and thereafter comparing electromagnetic radiation from the illumination that is ly reflected by said at least one object to a second threshold to determine transparency of said at least one object, wherein the second threshold lies above the first threshold, and thereafter setting the tion information.

. The method according to any of the preceding claims, wherein the step of analyzing the information from the optical scanning further ses determining height profiles of objects in the object stream. 6. The method according to any one of the preceding claims, wherein the lookup table is a one-, two- or N-dimensional lookup table. 7. The method according to any of the ing claims, wherein the step of analyzing the information from the optical scanning ses the use of deep learning or support vector es. 8. The method according to any of the preceding claims, further comprising a step of optically ng a zone on a ound element where a line illumination hits said background element, wherein the step of analyzing the ation from the optical scanning comprises determining whether material is present in the detection region based on the information from the optical scanning of the zone on the background. 9. The method according to claim 8, wherein the steps of optically scanning the zone on the background element and optically scanning the detection region are performed simultaneously with one camera.

. The method according to any of the preceding claims, where the step of illuminating said detection region with electromagnetic ion is done with a plurality of line illuminations for a plurality of detection regions and the step of optically scanning said detection region is done in a plurality of measurement lines for said detection regions. 11. The method according to claim 9, wherein the step of analyzing the information from the optical ng comprises determining the motion of the objects in the object stream. 12. The method according to claim 10, n the plurality of line illuminations have different wavelengths, wherein the step of analyzing the information from the optical scanning ses determining optical properties and physical ties of the objects in the object stream. 13. The method according to claim 10 or 12, wherein the plurality of line illuminations have different polarizations. 14. An apparatus for object classification, the apparatus being ured to perform the method according to any one of claims 1 – 13.

WO 43231 W0 43231 WO 43231 Fig. 5 WO 43231 . Background signal Object signal Dark zone for black reference Fig. 7

Claims (14)

1. A method for object classification, the method comprising the steps of: - guiding (S1) a continuous stream of objects (4) from a transport mechanism (2) directly into an unsupported path (6), along which said object stream (6) is fed through a detection region (12); - emitting electromagnetic radiation along a first direction (10) for illuminating (S2) said detection region (12), which emitted electromagnetic radiation forms a radiation band extending in a direction orthogonal to said first direction; - lly ng (S3) said detection region (12) to detect electromagnetic radiation reflected by the at least one object in the detection region (12) by viewing said detection region along a second direction (16), wherein the first direction (10) and the second direction (16) have a crosssection in the detection region (12) and forms an angle relative each other within the range of 3° - 80°; - analyzing (S4) the information from the optical scanning; and - fying (S5) objects from the object stream based on the analysis of the reflection information from the optical scanning; wherein the step of analyzing the information from the optical scanning comprises analyzing the objects based on the intensity and spread of the detected radiation from the optical scanning and wherein the step of ing the information from the optical scanning comprises comparing the information to information in a lookup table and/or comparing the information to thresholds.

2. The method according to claim 1, wherein said step of fying said object further comprising sorting the objects from the object stream in at least two ent directions based on the analysis of the reflection information from the optical scanning.

3. The method according to any of the preceding claims, n the step of analyzing the information from the optical scanning further comprises comparing the electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to ation in a lookup table and/or to one or more thresholds to determine transparency or reflection information of said at least one object.

4. The method according to any of the preceding claims, wherein the step of analyzing the information from the optical scanning comprises determining reflection information by comparing electromagnetic radiation from the illumination that is directly reflected by the at least one object in the object stream to a first threshold, and thereafter comparing electromagnetic radiation from the illumination that is ly reflected by said at least one object to a second threshold to determine transparency of said at least one object, wherein the second threshold lies above the first threshold, and thereafter setting the tion information.

5. The method according to any of the preceding claims, wherein the step of analyzing the information from the optical scanning further ses determining height profiles of objects in the object stream.

6. The method according to any one of the preceding claims, wherein the lookup table is a one-, two- or N-dimensional lookup table.

7. The method according to any of the ing claims, wherein the step of analyzing the information from the optical scanning ses the use of deep learning or support vector es.

8. The method according to any of the preceding claims, further comprising a step of optically ng a zone on a ound element where a line illumination hits said background element, wherein the step of analyzing the ation from the optical scanning comprises determining whether material is present in the detection region based on the information from the optical scanning of the zone on the background.

9. The method according to claim 8, wherein the steps of optically scanning the zone on the background element and optically scanning the detection region are performed simultaneously with one camera.

10. The method according to any of the preceding claims, where the step of illuminating said detection region with electromagnetic ion is done with a plurality of line illuminations for a plurality of detection regions and the step of optically scanning said detection region is done in a plurality of measurement lines for said detection regions.

11. The method according to claim 9, wherein the step of analyzing the information from the optical ng comprises determining the motion of the objects in the object stream.

12. The method according to claim 10, n the plurality of line illuminations have different wavelengths, wherein the step of analyzing the information from the optical scanning ses determining optical properties and physical ties of the objects in the object stream.

13. The method according to claim 10 or 12, wherein the plurality of line illuminations have different polarizations.

14. An apparatus for object classification, the apparatus being ured to perform the method according to any one of claims 1 – 13.