WO2016018157A1 - Article sorting system with synchronised lane detection - Google Patents

Article sorting system with synchronised lane detection Download PDF

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Publication number
WO2016018157A1
WO2016018157A1 PCT/NZ2014/000155 NZ2014000155W WO2016018157A1 WO 2016018157 A1 WO2016018157 A1 WO 2016018157A1 NZ 2014000155 W NZ2014000155 W NZ 2014000155W WO 2016018157 A1 WO2016018157 A1 WO 2016018157A1
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WO
WIPO (PCT)
Prior art keywords
articles
article
conveying
light
light source
Prior art date
Application number
PCT/NZ2014/000155
Other languages
French (fr)
Inventor
Kenneth Barry MOYNIHAN
James Duncan KINNIBURGH-WHITE
Original Assignee
Compac Technologies Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Compac Technologies Limited filed Critical Compac Technologies Limited
Priority to PCT/NZ2014/000155 priority Critical patent/WO2016018157A1/en
Publication of WO2016018157A1 publication Critical patent/WO2016018157A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
    • B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
    • B07C5/34—Sorting according to other particular properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
    • B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
    • B07C5/02—Measures preceding sorting, e.g. arranging articles in a stream orientating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
    • B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
    • B07C5/34—Sorting according to other particular properties
    • B07C5/342—Sorting according to other particular properties according to optical properties, e.g. colour
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
    • B07C2501/00—Sorting according to a characteristic or feature of the articles or material to be sorted
    • B07C2501/009—Sorting of fruit
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N2021/845—Objects on a conveyor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/85—Investigating moving fluids or granular solids

Definitions

  • the invention generally relates to article sorting systems comprising article conveyors. More particularly the invention relates to article sorting systems using image detection devices to capture images of conveyed articles and to sort the articles by certain detected characteristics.
  • Conveyors are often used in grading or sorting machines to transport articles through various measurement stages and to discharge the articles to sort them dependent on the
  • a common type of object that is graded and sorted by such a conveyor system is fruit.
  • Fruit may be sorted based on criteria such as weight, shape, colour, ripeness and any other characteristic.
  • Conveyor systems comprise devices to measure these characteristics while the fruit is being transported. For example, the characteristics can be detected and measured by visual scanning devices and/or cameras positioned above the conveyor. The position of each fruit and its respective characteristics can be tracked so that a discharge mechanism causes items of fruit to be unloaded from the conveyor and sent to the required destination, for example towards a chute or onto another conveyor.
  • Similar systems can be used to grade and sort other types of product based on similar characteristics or other characteristics specific to the type of product.
  • sorting conveyor have multiple endless conveyors on each of which are mounted a plurality of article carriers or cups.
  • the articles are each held by one of the carriers or cups meaning they are only free to take discrete positions on the conveyor and their position can be tracked using conventional tracking systems.
  • the multiple conveyors are arranged in parallel to convey articles along parallel paths.
  • articles may take any position on the conveyor and are not constrained to specific, discrete positioning locations.
  • inspection or detection points / stations At these points are cameras, usually mounted above the conveyors, that take images of the articles on the conveyors. These images are analysed and the articles are graded / sorted accordingly.
  • the articles are usually illuminated.
  • Multiple light sources may be used that each illuminates one of the conveyors.
  • One problem with this is that light from the light source for one conveyor can affect the illumination of articles on an adjacent or nearby conveyor.
  • conveyors may be illuminated unevenly. This may impact on the quality of images and the ability to analyse them. In turn, this may lead to errors in product sorting, which are not desired.
  • an article sorting system comprising:
  • one or more endless article conveyors configured to convey articles along a plurality of adjacent conveying paths
  • At least one light source positioned to illuminate the conveying paths
  • At least one camera positioned to image articles conveyed along the conveying paths; light source control means for controlling the at least one light source to independently illuminate each conveying path in a conveying path illumination order;
  • camera control means for controlling the at least one camera to image the articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources; and discharge means for selectively discharging articles from the article conveyors to one or more discharge locations.
  • the light sources when articles are conveyed along the conveying paths, the light sources illuminate the articles. It will further be understood that only a single part or region of the conveying path may be illuminated, for example to illuminate a single article on the conveying path or a number of articles.
  • the light source control means and camera control means are configured to illuminate and image at least a first article on a first conveying path followed by at least a second article on a second conveying path, and so on to sequentially illuminate and image at least an article on each conveying path before illuminating and imaging further articles on the conveying paths, sequentially by conveying path. That is, the conveying path illumination order is sequential.
  • the at least one light source is configured to illuminate the conveying paths with multiple types of light. More preferably, the system comprises a plurality of light sources, each configured to illuminate the conveying paths with a different type of light. Examples of types of light include but are not limited to: light in a specified range of the electromagnetic spectrum (e.g. red light, green light, blue light, ultraviolet, infra-red); evenly distributed light; directional light; or a light that is projected in a pattern.
  • types of light include but are not limited to: light in a specified range of the electromagnetic spectrum (e.g. red light, green light, blue light, ultraviolet, infra-red); evenly distributed light; directional light; or a light that is projected in a pattern.
  • the light source control means is configured to
  • the articles independently illuminate articles on each conveying path with each type of light in a light type illumination order.
  • the articles are sequentially illuminated by light type and then sequentially illuminated by conveying path.
  • the articles are sequentially illuminated by conveying path and then sequentially illuminated by light type.
  • the light source control means and camera control means are configured to illuminate and image at least two of the articles simultaneously. More preferably, said at least two of the articles are sufficiently spaced apart when illuminated and imaged to substantially avoid light interference from the light sources between said articles. More preferably, said at least two articles are conveyed on different conveying paths, said different conveying paths being sufficiently spaced apart to substantially avoid light interference from the light sources between said different conveying paths.
  • the sorting system comprises means for generating a synchronising pulse signal to synchronise illumination of the at least one light source and imaging by the at least one camera.
  • the at least one light source illuminates the articles substantially only when the at least one camera images the articles.
  • the sorting system comprises means for controlling the discharge means based on analysis of images captured by the at least one camera.
  • the sorting system comprises means for generating data indicative of how the articles should be sorted dependent on the analysis of the images.
  • the sorting system comprises analysis means for receiving image data based on the images and analysing the image data to determine characteristics of the imaged articles.
  • each conveyor comprises a plurality of discrete article receiving means.
  • an article sorting system comprising:
  • one or more endless article conveyors configured to convey articles along at least first and second adjacent conveying paths
  • At least one light source positioned to illuminate articles on the conveyors
  • At least one camera positioned to image articles on the conveyors illuminated by the at least one light source
  • light source control means for controlling the at least one light source to independently illuminate at least a first article on the first conveying path and subsequently to independently illuminate at least a second article on the second conveying path;
  • camera control means for controlling the at least one camera to independently image the first and second articles when the respective conveying paths are illuminated by at least one of the light sources; and discharge means for selectively discharging articles from the article conveyors to one or more discharge locations.
  • the article sorting system further comprises third and, optionally, further conveying paths, wherein the at least one light source is controlled to independently illuminate articles on each conveying path in a conveying path illumination order and the at least one camera is controlled to image the articles when illuminated by at least one of the light sources in the conveying path illumination order.
  • a computer-implemented method of imaging articles on a conveying system comprising:
  • the method comprises controlling the at least one light source and the at least one camera to illuminate and image at least a first article on a first conveying path followed by at least a second article on a second conveying path, and so on to sequentially illuminate and image at least an article on each conveying path before illuminating and imaging further articles on the conveying paths, sequentially by conveying path.
  • the method comprises controlling the at least one light source to illuminate the conveying paths with multiple types of light. More preferably, the method comprises controlling a plurality of light sources to each independently illuminate the conveying paths with a different type of light.
  • the method comprises controlling the at least one light source to independently illuminate articles on each conveying path with each type of light in a light type illumination order.
  • the method comprises sequentially illuminating the articles by light type and then sequentially illuminating the articles by conveying path.
  • the method comprises sequentially illuminating the articles by conveying path and then sequentially illuminating the articles by light type.
  • the method comprises controlling the at least one light source and the at least one camera to illuminate and image at least two of the articles simultaneously. More preferably, said at least two of the articles are sufficiently spaced apart when illuminated and imaged to substantially avoid light interference from the light sources between said articles.
  • the method comprises generating a synchronising pulse signal to synchronise illumination of the at least one light source and imaging by the at least one camera.
  • the method comprises controlling the at least one light source to illuminate the articles substantially only when the at least one camera images the articles.
  • an apparatus for imaging articles on a conveying system comprising:
  • a computer-implemented method of sorting articles on a conveyor system comprising:
  • the method comprises controlling the article discharge means based on analysis of images captured by the at least one camera.
  • the method comprises generating data indicative of how the articles should be sorted dependent on the analysis of the images.
  • the method comprises receiving image data based on the images and analysing the image data to determine characteristics of the imaged articles.
  • an apparatus for imaging articles on a conveying system comprising:
  • Figure 1 is a cross-sectional view illustration of an article sorting system according to an embodiment of the invention
  • Figure 2 is a schematic illustration of an article analysis system according to one embodiment of the invention.
  • Figure 1 is a cross-sectional view illustration of an article sorting system 10 according to an embodiment of the invention.
  • Article sorting system comprises a number of endless conveyors 11 that are configured to convey articles 12 along conveying paths.
  • the articles are carried in or on discrete article receivers or carriers 13 in the form of cups or cup-like structures formed by the article receivers so as to retain the articles when they are conveyed.
  • the conveying paths are generally defined by rows of article receivers 13 such that all articles conveyed by receivers in each row follow the same conveying path.
  • the invention is not limited by the type of articles that are conveyed by the conveyors and sorted by the sorting system.
  • the system 10 is used to sort fruit.
  • the invention is not limited to conveyors able to carry articles in only discrete receivers.
  • An example of an embodiment in which articles are limited to sitting in discrete carriers will be described below but, in other embodiments, articles may be carried on conveying paths on conveyors on which the articles can take any position.
  • An example of such an alternative embodiment is a sorting system comprising a number of conveyors comprising a series of support members on which the articles sit that can drop away to eject articles out the bottom of the conveyor to selectively sort the articles, the articles being able to take any position on the support members.
  • the conveyors 11 may be configured in any manner in order to define adjacent conveying paths along which articles may travel.
  • the conveying paths may be defined by one or more endless conveyors.
  • Each endless conveyor may define more than one conveying path, for example if a conveying assembly has a single drive mechanism that drives two or more different rows of article carriers.
  • Embodiments of the invention have different configurations of the conveying system.
  • the sorting system 10 further comprises light sources 14 positioned where they can illuminate articles travelling along the conveying paths. Since the conveying paths are the space through which the articles travel, the light sources 14 can also be said to illuminate the conveying paths. The light sources are positioned generally above conveyors 11 and illuminate a particular part of the conveying path.
  • the region of illumination from each light source, or from a plurality of light sources may be any size, although in some embodiments it is big enough to illuminate a single article being conveyed by the conveyer.
  • the light sources are collectively able to illuminate all of the conveying paths.
  • each light source illuminates one conveying path.
  • the light sources may be controllable to alter their zone of illumination, e.g. by moving the light source or moving lenses or mirrors or the like using a suitable control mechanism.
  • the sorting system 10 further comprises cameras 15 positioned to image the articles when conveyed along the conveying paths by the conveyors 11.
  • the cameras 15 are also positioned generally above the conveyor to image the articles conveyed by the article receivers / carriers 13. Any type of camera may be used although in preferred embodiments of the invention the cameras are digital cameras that operate by generating image data indicative of incident light received.
  • the positioning of cameras 15 is such that the articles are imaged by the cameras at the position the articles are illuminated by the light sources 14. That is, the cameras 15 are generally targeted at the regions of illumination created by the light sources 14.
  • each camera images one conveying path.
  • the cameras may be controllable to alter the region from which they capture images, e.g. by moving the cameras or by moving lenses or mirrors or the like using a suitable control mechanism.
  • each light illuminates articles on one of the conveying paths and images of the articles on said conveying path are captured by one of the cameras.
  • Articles to be sorted travel along the conveyors 11 and are imaged by the cameras 15 when illuminated by the light sources 14, The image data from cameras 15 is analysed to determine characteristics of the imaged articles. The articles are sorted based on the detected
  • characteristics for example to collect articles sharing certain characteristics together.
  • the invention is not limited to the manner in which the image data is analysed, nor is it limited to the characteristics by which the articles are sorted.
  • characteristics by which the articles may be sorted are: size, shape, colour, ripeness, and weight.
  • Other characteristics in the case of fruit sorting and sorting other types of articles will be evident to the skilled reader.
  • Any suitable system to analyse the data generated by the cameras and to sort the articles may be used.
  • a processor or computer may be used to analyse the data, determine the characteristic by which an article is to be sorted and determine how the articles should be sorted based on that analysis and determination. That processor may then directly or indirectly control an article discharge mechanism to discharge articles from the conveyor in order to sort them. Processors configured to perform these steps are known in the art.
  • the invention is not limited by the manner or mechanism by which articles are discharged from the conveyor. Any suitable article ejection or discharge means may be used, for example an actuator that causes the article carriers to tip sideways, ejector paddles, jets of air, and the like.
  • the articles may be selectively discharged to one or more article receiving locations in order to be sorted. As is known in the art, the receiving locations may comprise buckets, chutes, other conveyors, etc.
  • One way to improve the quality of the image data is to reduce the amount of interference or cross-illumination between the conveying lanes or paths.
  • embodiments of the invention control the illumination of the articles and image data capture so that articles in each conveying path are illuminated and imaged independently in a particular order.
  • no two conveying paths are lit simultaneously which, if both illuminated, would result in inter-lane lighting interference sufficient to degrade the quality of the image data and/or the performance of the sorting system.
  • simultaneous lighting of conveying paths occurs, but in a way to minimise cross-path lighting interference, for example by simultaneously lighting conveying lanes that are separated by a sufficient distance to minimise such interference.
  • the light sources 14 are controlled such that they illuminate each conveying path in turn or in an order.
  • the cameras are controlled such that they capture images of the conveying paths (and the articles) when the conveying paths are illuminated, and therefore in turn.
  • the conveying path illumination order may be sequential or non-sequential. That is, the conveying paths may be independently illuminated in a sequence that is predetermined and may be repeated over and over again. Alternatively, the conveying paths may be independently illuminated in a non-sequential order that is determined based on other factors, such as the detection of articles on the conveyors.
  • a sorting system comprises a conveyor having four lanes or paths P1 - P4 along which articles are conveyed.
  • the system comprises four light sources L1 - L4 and four cameras C1 - C4.
  • Light source L1 illuminates articles at a predetermined point on path P1 and camera C1 images the articles on path P1 at that point, and so on. Operation of the light sources and cameras is synchronised to work as follows. Firstly, light source L1 is illuminated and camera C1 captures one or more images. Light source L1 is then de-activated and camera C1 ceases capturing image data. Light source L2 is then illuminated and camera C2 captures at least one image or some image data.
  • light source L3 and camera C3, then light source L4 and camera C4 are in turn activated and subsequently de-activated in a similar manner before light source L1 and camera C1 are operated again. That is, the sequence of operation is: L1-C1 , L2-C2, L3-C3, L4-C4, L1-C1 , L2- C2, etc. In this way, articles on the conveyors are illuminated individually and can be imaged without interference or incidental illumination from another conveying path.
  • a sorting system operates four light sources L1 - L4 and four cameras C1 - C4 across four lanes or paths by detecting which lanes/paths have articles present and activating the lights / cameras based on the presence of articles on the respective lanes / paths.
  • Such a mode of operation may result, for example, in an illumination and lighting order of: L2-C2, L3-C3, L1-C1 , L3-C3, L4-C4, L1-C1 , L2-C2, L1-C1 , L4-C4, L2-C2, and so on without any predetermined sequence or order.
  • the timing of the synchronisation between light sources and cameras is selected at least partly dependent on the speed of the conveyors.
  • Other factors affecting the timing of ordered illumination and imaging between the lanes include the exposure time of the cameras and the brightness of the lights. It will be appreciated that these factors may be adjusted to balance capturing image data of adequate quality to sort the fruit with the speed with which articles may be processed in order to achieve a desired degree of sorting accuracy.
  • embodiments of the invention comprise light source control means configured to control the light sources to illuminate the conveying paths independently in a conveying path illumination order and camera control means configured to image the articles conveyed along the conveying paths in that order, i.e. as the paths are illuminated.
  • Any suitable control means may be used and the invention is not limited to the manner in which the light sources and cameras are controlled.
  • the control means for each light source and/or each camera may be embodied in the same control device.
  • the operation of either each camera or each light source may trigger operation of the corresponding light source or camera respectively.
  • the number of light sources and/or cameras used may not necessarily correspond to the number of conveying paths to be analysed.
  • the position of a light source / camera, or the light emitted from or incident on said light source / camera may be controlled in order to illuminate or image two conveying paths using the same light source or camera, for example.
  • a conveying path may be illuminated and/or imaged by two or more light sources and/or cameras respectively.
  • the sorting system is configured to illuminate each conveying path with more than one type of light. This may be achieved using a number of light sources able to illuminate each conveying path or using a single light source for each conveying path that is able to illuminate the conveying path with more than one type of light.
  • the types of light may include different parts of the electromagnetic spectrum (i.e. light of certain wavelength ranges such as ultra-violet, infra-red, red, green, blue, etc) or light having other qualities such as having an even distribution of brightness across a region or originating from a particular position (e.g. highly directional light) or a light that is projected in a pattern.
  • Each conveying path is illuminated by each type of light independently and images are captured when articles on the conveying paths are illuminated. There may be a sequential or nonsequential ordering of illumination by each light type, or light type illumination order. The ordered illumination of conveying paths may occur by conveying path and then by light source or vice versa.
  • a sorting system has conveying paths P1 to P4.
  • Cameras C1 to C4 are each positioned to image articles on the correspondingly numbered conveying path.
  • Each conveying path can be illuminated by light types A, B and C such that light types L1A, L1 B and L1C illuminate articles on path P1 , and so on.
  • Light types A, B and C may be generated by three different light sources or they may be generated by the same light source that is able to alter the type of light it generates, for example filters.
  • the light source and cameras are controlled to illuminate and image the articles in the following order: L1A-C1 , L1 B-C1 , L1 C-C1 , L2A-C2, L2B-C2, L2C-C2, L3A-C3 and so on.
  • the order may be: L1A-C1 , L2A-C2, L3A-C3, L4A-C4, L1 B-C1 , L2B-C2, and so on.
  • both the conveying path illumination order and the light type illumination order is sequential.
  • one or both of the conveying path illumination order and the light type illumination order is non-sequential and determined based on factors such as the detection of articles on the respective conveying paths and the type of articles detected in order to decide the ordering of the illumination by conveying path and by light type. Simultaneous illumination / capture
  • some of the conveying paths are illuminated and imaged simultaneously, or part of the image capture time of at least two lanes may overlap. This may occur, for example, where two conveying paths are positioned sufficiently far apart that light from a light source incident on one of the conveying paths does not illuminate another conveying path, or the light source does not interfere sufficiently with another conveying path to substantially alter the quality of image data captured from the other conveying path. This may enable higher rates of sorting to be achieved in sorting systems with large numbers of conveyors where, if images of more than one lane of articles could not be captured
  • the conveyors would need to be slowed to rates below the desired article processing rate. It may also enable the light sources to be driven at higher currents, which may result in a higher light output with less heat dissipation and lower overall power consumption than could otherwise be achieved.
  • simultaneous illumination of two areas of a single conveying path may occur, with the two illuminated areas being separated by a sufficient longitudinal distance that interference between the respective light sources is minimised or reduced to a tolerable level.
  • FIG. 2 is a schematic illustration of an article analysis system 20 according to one embodiment of the invention.
  • Analysis system 20 comprises a number of lanes 21 along which articles are conveyed. Articles in each lane are able to be illuminated by lane lighting systems 22, which include one or more light sources which may take the form of one or more LED light assemblies or any other form of lighting.
  • the light from the LED assemblies may be focussed at a region in the respective conveying lane 21 using a plano-convex lens.
  • the light may also be polarised using, for example, a polariser across the lens.
  • Articles in each lane are able to be imaged by one or more cameras 23.
  • the cameras 23 for each lane may include a master camera and 'slave' cameras.
  • One of the cameras 23 generates a synchronising pulse signal from which the timing of activation of the other cameras 23 and LEDs in lane lighting systems 22 is taken.
  • the camera that generates the synchronising pulse signal (which may be referred to as the 'system master' camera) does not have sufficient power to output a strong enough pulse signal to synchronise all the other slave cameras and LEDs directly so camera synchronisation buffers 26 are used - one for each lane master camera 23.
  • the camera synchronisation buffers 26 receive the synchronisation pulse outputted by the system master camera and buffer the pulse to boost its power, thus allowing it to synchronise the cameras and LEDs in a number of lanes from a single master camera.
  • camera synchronisation hubs may be connected between the camera synchronisation buffers 26 and the slave cameras 24.
  • the hubs join up the appropriate synchronisation signals between the cameras 24 and may also power the cameras 24 via the same cable.
  • No power sources are illustrated in Figure 2 but it will be apparent to the skilled addressee how power can be supplied to the components of the article analysis system 20.
  • the synchronisation pulse generated by the master camera is supplied by the camera synchronisation buffers 26 to lane lighting systems 28.
  • Each lane lighting system comprises one or more light sources, for example LED assemblies and may further comprise drivers for controlling activation of the light sources.
  • the drivers Based on the timing of the synchronisation pulse signal received, the drivers activate the LEDs 22 for that lane using a pulsed current signal.
  • the illumination time of each 'flash' of an LED is configurable, as is the time delay between flashes for each LED.
  • the current and/or power of the LEDs may also be configurable.
  • each LED assembly or array may be configurable to aid grading performance depending on the nature of the article being sorted or the characteristic of the article that is to be determined.
  • an LED assembly may comprise both white and infra-red lights and the type of light illuminated in order to image the articles may be selected to optimise (or at least increase) grading.
  • These LED settings may be configured from software running on a computing device 201 or other processor controlling operation of the article analysis system 20 or components thereof.
  • the timing of illumination of the LEDs is set so that they are only illuminated when the respective cameras 23/24 are imaging the articles on the respective conveying lane 21 . This saves power and reduces the delay necessary between imaging lanes.
  • One or more computing or processing devices 201 are coupled within the system and are operable to control operation of the system.
  • computer 201 is connected to the lane lighting systems 28 and cameras 23. Connection of the computer 201 to the components of the system may be as shown in Figure 2 or in any other manner, for example through direct connection of the computer 201 to each component, or a combination of direct and indirect connections.
  • the computers 201 may be configured to run software with which the system can be controlled.
  • images of the conveyed articles taken by cameras 23/24 are provided to the computers where suitable image processing software is used to analyse the images of the articles in order to determine characteristics of them and to determine how the articles should be sorted (i.e. grading).
  • the system comprises switches, for example connected between the cameras and computing device / processor to enable the computing device / processor to control and communicate with each camera individually.
  • the LEDs and cameras are all mounted above the conveying lanes on a supporting framework or cabinet.
  • Embodiments of the invention have been found to dramatically improve performance compared to conventional sorting systems when grading fruit.
  • the invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

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  • Sorting Of Articles (AREA)

Abstract

The invention provides an article sorting system, apparatus and method of control comprising lights and cameras positioned to illuminate and image articles conveyed along one or more endless article conveyors. The lights are controlled to independently illuminate each conveying path in a sequential or non-sequential manner and the cameras are controlled to image the articles when illuminated by the lights. The system helps avoid cross-lane lighting interference and helps ensure accurate detection and measurement of articles on the conveyors.

Description

ARTICLE SORTING SYSTEM WITH SYNCHRONISED LANE DETECTION Field of Invention The invention generally relates to article sorting systems comprising article conveyors. More particularly the invention relates to article sorting systems using image detection devices to capture images of conveyed articles and to sort the articles by certain detected characteristics.
Background to the Invention
Conveyors are often used in grading or sorting machines to transport articles through various measurement stages and to discharge the articles to sort them dependent on the
measurements. A common type of object that is graded and sorted by such a conveyor system is fruit. Fruit may be sorted based on criteria such as weight, shape, colour, ripeness and any other characteristic. Conveyor systems comprise devices to measure these characteristics while the fruit is being transported. For example, the characteristics can be detected and measured by visual scanning devices and/or cameras positioned above the conveyor. The position of each fruit and its respective characteristics can be tracked so that a discharge mechanism causes items of fruit to be unloaded from the conveyor and sent to the required destination, for example towards a chute or onto another conveyor.
Similar systems can be used to grade and sort other types of product based on similar characteristics or other characteristics specific to the type of product.
Some types of sorting conveyor have multiple endless conveyors on each of which are mounted a plurality of article carriers or cups. The articles are each held by one of the carriers or cups meaning they are only free to take discrete positions on the conveyor and their position can be tracked using conventional tracking systems. The multiple conveyors are arranged in parallel to convey articles along parallel paths. On other types of sorting conveyors, articles may take any position on the conveyor and are not constrained to specific, discrete positioning locations. In one or more locations along the conveyors there are inspection or detection points / stations. At these points are cameras, usually mounted above the conveyors, that take images of the articles on the conveyors. These images are analysed and the articles are graded / sorted accordingly.
To ensure clear images of the articles are captured, the articles are usually illuminated. Multiple light sources may be used that each illuminates one of the conveyors. One problem with this is that light from the light source for one conveyor can affect the illumination of articles on an adjacent or nearby conveyor. In particular, conveyors may be illuminated unevenly. This may impact on the quality of images and the ability to analyse them. In turn, this may lead to errors in product sorting, which are not desired.
Object of the Invention
It is an object of the invention to provide an improved article sorting system that at least addresses, or goes some way to address, the problems of conventional systems described above.
Alternatively, it is an object of the invention to provide an improved method or apparatus of imaging and/or sorting articles. Alternatively, it is an object of the invention to at least provide the public with a useful choice.
Summary of the Invention
According to a first aspect of the invention, there is provided an article sorting system comprising:
one or more endless article conveyors configured to convey articles along a plurality of adjacent conveying paths;
at least one light source positioned to illuminate the conveying paths;
at least one camera positioned to image articles conveyed along the conveying paths; light source control means for controlling the at least one light source to independently illuminate each conveying path in a conveying path illumination order;
camera control means for controlling the at least one camera to image the articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources; and discharge means for selectively discharging articles from the article conveyors to one or more discharge locations.
It will be understood that, when articles are conveyed along the conveying paths, the light sources illuminate the articles. It will further be understood that only a single part or region of the conveying path may be illuminated, for example to illuminate a single article on the conveying path or a number of articles.
Preferably, the light source control means and camera control means are configured to illuminate and image at least a first article on a first conveying path followed by at least a second article on a second conveying path, and so on to sequentially illuminate and image at least an article on each conveying path before illuminating and imaging further articles on the conveying paths, sequentially by conveying path. That is, the conveying path illumination order is sequential.
In some embodiments of the invention, the at least one light source is configured to illuminate the conveying paths with multiple types of light. More preferably, the system comprises a plurality of light sources, each configured to illuminate the conveying paths with a different type of light. Examples of types of light include but are not limited to: light in a specified range of the electromagnetic spectrum (e.g. red light, green light, blue light, ultraviolet, infra-red); evenly distributed light; directional light; or a light that is projected in a pattern.
In examples of such an embodiment, the light source control means is configured to
independently illuminate articles on each conveying path with each type of light in a light type illumination order. In one embodiment, the articles are sequentially illuminated by light type and then sequentially illuminated by conveying path. In an alternative embodiment, the articles are sequentially illuminated by conveying path and then sequentially illuminated by light type.
Preferably, the light source control means and camera control means are configured to illuminate and image at least two of the articles simultaneously. More preferably, said at least two of the articles are sufficiently spaced apart when illuminated and imaged to substantially avoid light interference from the light sources between said articles. More preferably, said at least two articles are conveyed on different conveying paths, said different conveying paths being sufficiently spaced apart to substantially avoid light interference from the light sources between said different conveying paths. Preferably, the sorting system comprises means for generating a synchronising pulse signal to synchronise illumination of the at least one light source and imaging by the at least one camera.
In one embodiment, the at least one light source illuminates the articles substantially only when the at least one camera images the articles.
Preferably, the sorting system comprises means for controlling the discharge means based on analysis of images captured by the at least one camera.
Preferably, the sorting system comprises means for generating data indicative of how the articles should be sorted dependent on the analysis of the images.
More preferably, the sorting system comprises analysis means for receiving image data based on the images and analysing the image data to determine characteristics of the imaged articles. Preferably, each conveyor comprises a plurality of discrete article receiving means.
According to a second aspect of the invention, there is provided an article sorting system comprising:
one or more endless article conveyors configured to convey articles along at least first and second adjacent conveying paths;
at least one light source positioned to illuminate articles on the conveyors;
at least one camera positioned to image articles on the conveyors illuminated by the at least one light source;
light source control means for controlling the at least one light source to independently illuminate at least a first article on the first conveying path and subsequently to independently illuminate at least a second article on the second conveying path;
camera control means for controlling the at least one camera to independently image the first and second articles when the respective conveying paths are illuminated by at least one of the light sources; and discharge means for selectively discharging articles from the article conveyors to one or more discharge locations.
Preferably, the article sorting system further comprises third and, optionally, further conveying paths, wherein the at least one light source is controlled to independently illuminate articles on each conveying path in a conveying path illumination order and the at least one camera is controlled to image the articles when illuminated by at least one of the light sources in the conveying path illumination order. According to a third aspect of the invention, there is provided a computer-implemented method of imaging articles on a conveying system comprising:
controlling at least one light source to independently illuminate a plurality of adjacent conveying paths in a conveying path illumination order; and
controlling at least one camera to image articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources.
Preferably, the method comprises controlling the at least one light source and the at least one camera to illuminate and image at least a first article on a first conveying path followed by at least a second article on a second conveying path, and so on to sequentially illuminate and image at least an article on each conveying path before illuminating and imaging further articles on the conveying paths, sequentially by conveying path.
In some embodiments of the invention, the method comprises controlling the at least one light source to illuminate the conveying paths with multiple types of light. More preferably, the method comprises controlling a plurality of light sources to each independently illuminate the conveying paths with a different type of light.
In examples of such an embodiment, the method comprises controlling the at least one light source to independently illuminate articles on each conveying path with each type of light in a light type illumination order. In one embodiment, the method comprises sequentially illuminating the articles by light type and then sequentially illuminating the articles by conveying path. In an alternative embodiment, the method comprises sequentially illuminating the articles by conveying path and then sequentially illuminating the articles by light type. Preferably, the method comprises controlling the at least one light source and the at least one camera to illuminate and image at least two of the articles simultaneously. More preferably, said at least two of the articles are sufficiently spaced apart when illuminated and imaged to substantially avoid light interference from the light sources between said articles.
More preferably, said at least two articles are conveyed on different conveying paths, said different conveying paths being sufficiently spaced apart to substantially avoid light interference from the light sources between said different conveying paths. Preferably, the method comprises generating a synchronising pulse signal to synchronise illumination of the at least one light source and imaging by the at least one camera.
In one embodiment, the method comprises controlling the at least one light source to illuminate the articles substantially only when the at least one camera images the articles.
According to a fourth aspect of the invention, there is provided an apparatus for imaging articles on a conveying system comprising:
means for controlling at least one light source to independently illuminate a plurality of adjacent conveying paths in a conveying path illumination order; and
means for controlling at least one camera to image articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources.
According to a fifth aspect of the invention, there is provided a computer-implemented method of sorting articles on a conveyor system comprising:
controlling at least one light source to independently illuminate a plurality of adjacent conveying paths in a conveying path illumination order;
controlling at least one camera to image articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources;
receiving data indicative of how an inspected one of the articles should be sorted based on a characteristic of the inspected article; and
controlling actuation of article discharge means in order to discharge the inspected article from the respective conveying path dependent on the data indicative of how the inspected article should be sorted. Preferably, the method comprises controlling the article discharge means based on analysis of images captured by the at least one camera.
Preferably, the method comprises generating data indicative of how the articles should be sorted dependent on the analysis of the images.
More preferably, the method comprises receiving image data based on the images and analysing the image data to determine characteristics of the imaged articles. According to a sixth aspect of the invention, there is provided an apparatus for imaging articles on a conveying system comprising:
means for controlling at least one light source to independently illuminate a plurality of adjacent conveying paths in a conveying path illumination order;
means for controlling at least one camera to image articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources;
means for receiving data indicative of how an inspected one of the articles should be sorted based on a characteristic of the inspected article; and
means for controlling actuation of article discharge means in order to discharge the inspected article from the respective conveying path dependent on the data indicative of how the inspected article should be sorted.
Further aspects of the invention, which should be considered in all its novel aspects, will become apparent to those skilled in the art upon reading of the following description which provides at least one example of a practical application of the invention.
Brief Description of the Drawings
One or more embodiments of the invention will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which:
Figure 1 is a cross-sectional view illustration of an article sorting system according to an embodiment of the invention; Figure 2 is a schematic illustration of an article analysis system according to one embodiment of the invention.
Detailed Description of Preferred Embodiments of the Invention
Sorting system
Figure 1 is a cross-sectional view illustration of an article sorting system 10 according to an embodiment of the invention. Article sorting system comprises a number of endless conveyors 11 that are configured to convey articles 12 along conveying paths. The articles are carried in or on discrete article receivers or carriers 13 in the form of cups or cup-like structures formed by the article receivers so as to retain the articles when they are conveyed. The conveying paths are generally defined by rows of article receivers 13 such that all articles conveyed by receivers in each row follow the same conveying path.
The invention is not limited by the type of articles that are conveyed by the conveyors and sorted by the sorting system. In some embodiments, the system 10 is used to sort fruit.
Furthermore, the invention is not limited to conveyors able to carry articles in only discrete receivers. An example of an embodiment in which articles are limited to sitting in discrete carriers will be described below but, in other embodiments, articles may be carried on conveying paths on conveyors on which the articles can take any position. An example of such an alternative embodiment is a sorting system comprising a number of conveyors comprising a series of support members on which the articles sit that can drop away to eject articles out the bottom of the conveyor to selectively sort the articles, the articles being able to take any position on the support members.
Referring again to the embodiment of Figure 1 , the conveyors 11 may be configured in any manner in order to define adjacent conveying paths along which articles may travel. The conveying paths may be defined by one or more endless conveyors. Each endless conveyor may define more than one conveying path, for example if a conveying assembly has a single drive mechanism that drives two or more different rows of article carriers. Embodiments of the invention have different configurations of the conveying system. The sorting system 10 further comprises light sources 14 positioned where they can illuminate articles travelling along the conveying paths. Since the conveying paths are the space through which the articles travel, the light sources 14 can also be said to illuminate the conveying paths. The light sources are positioned generally above conveyors 11 and illuminate a particular part of the conveying path. The region of illumination from each light source, or from a plurality of light sources, may be any size, although in some embodiments it is big enough to illuminate a single article being conveyed by the conveyer. The light sources are collectively able to illuminate all of the conveying paths.
In one embodiment of the invention there is a one-to-one relationship between the light sources
14 and the conveying paths along which articles 12 are conveyed. For example, each light source illuminates one conveying path. In other embodiments, there may be a different number of light sources to conveying paths. In embodiments where there are fewer light sources than conveying paths, the light sources may be controllable to alter their zone of illumination, e.g. by moving the light source or moving lenses or mirrors or the like using a suitable control mechanism.
The sorting system 10 further comprises cameras 15 positioned to image the articles when conveyed along the conveying paths by the conveyors 11. The cameras 15 are also positioned generally above the conveyor to image the articles conveyed by the article receivers / carriers 13. Any type of camera may be used although in preferred embodiments of the invention the cameras are digital cameras that operate by generating image data indicative of incident light received. The positioning of cameras 15 is such that the articles are imaged by the cameras at the position the articles are illuminated by the light sources 14. That is, the cameras 15 are generally targeted at the regions of illumination created by the light sources 14.
In some embodiments of the invention there is a one-to-one relationship between the cameras
15 and the conveying paths along which articles 12 are conveyed. For example, each camera images one conveying path. In other embodiments, there may be a different number of cameras to conveying paths. In embodiments where there are fewer cameras than conveying paths, the cameras may be controllable to alter the region from which they capture images, e.g. by moving the cameras or by moving lenses or mirrors or the like using a suitable control mechanism. In some embodiments there is the same number of cameras as light sources. In one such embodiment, each light illuminates articles on one of the conveying paths and images of the articles on said conveying path are captured by one of the cameras. Articles to be sorted travel along the conveyors 11 and are imaged by the cameras 15 when illuminated by the light sources 14, The image data from cameras 15 is analysed to determine characteristics of the imaged articles. The articles are sorted based on the detected
characteristics, for example to collect articles sharing certain characteristics together. The invention is not limited to the manner in which the image data is analysed, nor is it limited to the characteristics by which the articles are sorted. Non-limiting examples of characteristics by which the articles may be sorted (in the case of fruit) are: size, shape, colour, ripeness, and weight. Other characteristics in the case of fruit sorting and sorting other types of articles will be evident to the skilled reader.
Any suitable system to analyse the data generated by the cameras and to sort the articles may be used. For example, a processor or computer may be used to analyse the data, determine the characteristic by which an article is to be sorted and determine how the articles should be sorted based on that analysis and determination. That processor may then directly or indirectly control an article discharge mechanism to discharge articles from the conveyor in order to sort them. Processors configured to perform these steps are known in the art.
The invention is not limited by the manner or mechanism by which articles are discharged from the conveyor. Any suitable article ejection or discharge means may be used, for example an actuator that causes the article carriers to tip sideways, ejector paddles, jets of air, and the like. The articles may be selectively discharged to one or more article receiving locations in order to be sorted. As is known in the art, the receiving locations may comprise buckets, chutes, other conveyors, etc.
Light and image synchronisation
The performance of a sorting system such as has been described with reference to Figure 1 depends on correctly determining how each individual article (such as a fruit) should be sorted. This depends on correctly analysing the image data of the articles, which itself depends on the quality of the image data. Incorrect sorting results from, amongst other things, poorly imaged articles.
One way to improve the quality of the image data is to reduce the amount of interference or cross-illumination between the conveying lanes or paths. In order to achieve this, embodiments of the invention control the illumination of the articles and image data capture so that articles in each conveying path are illuminated and imaged independently in a particular order.
In one embodiment, no two conveying paths are lit simultaneously which, if both illuminated, would result in inter-lane lighting interference sufficient to degrade the quality of the image data and/or the performance of the sorting system. In some embodiments, simultaneous lighting of conveying paths occurs, but in a way to minimise cross-path lighting interference, for example by simultaneously lighting conveying lanes that are separated by a sufficient distance to minimise such interference.
With reference again to Figure 1 , the light sources 14 are controlled such that they illuminate each conveying path in turn or in an order. The cameras are controlled such that they capture images of the conveying paths (and the articles) when the conveying paths are illuminated, and therefore in turn.
The conveying path illumination order may be sequential or non-sequential. That is, the conveying paths may be independently illuminated in a sequence that is predetermined and may be repeated over and over again. Alternatively, the conveying paths may be independently illuminated in a non-sequential order that is determined based on other factors, such as the detection of articles on the conveyors.
In one example of a sequential conveying path illumination order, a sorting system comprises a conveyor having four lanes or paths P1 - P4 along which articles are conveyed. The system comprises four light sources L1 - L4 and four cameras C1 - C4. Light source L1 illuminates articles at a predetermined point on path P1 and camera C1 images the articles on path P1 at that point, and so on. Operation of the light sources and cameras is synchronised to work as follows. Firstly, light source L1 is illuminated and camera C1 captures one or more images. Light source L1 is then de-activated and camera C1 ceases capturing image data. Light source L2 is then illuminated and camera C2 captures at least one image or some image data. Then light source L3 and camera C3, then light source L4 and camera C4 are in turn activated and subsequently de-activated in a similar manner before light source L1 and camera C1 are operated again. That is, the sequence of operation is: L1-C1 , L2-C2, L3-C3, L4-C4, L1-C1 , L2- C2, etc. In this way, articles on the conveyors are illuminated individually and can be imaged without interference or incidental illumination from another conveying path. In an example of a non-sequential conveying path illumination order, a sorting system operates four light sources L1 - L4 and four cameras C1 - C4 across four lanes or paths by detecting which lanes/paths have articles present and activating the lights / cameras based on the presence of articles on the respective lanes / paths. Such a mode of operation may result, for example, in an illumination and lighting order of: L2-C2, L3-C3, L1-C1 , L3-C3, L4-C4, L1-C1 , L2-C2, L1-C1 , L4-C4, L2-C2, and so on without any predetermined sequence or order.
It will be appreciated that, in order to image all the articles passing along the conveyors, the timing of the synchronisation between light sources and cameras is selected at least partly dependent on the speed of the conveyors. Other factors affecting the timing of ordered illumination and imaging between the lanes include the exposure time of the cameras and the brightness of the lights. It will be appreciated that these factors may be adjusted to balance capturing image data of adequate quality to sort the fruit with the speed with which articles may be processed in order to achieve a desired degree of sorting accuracy.
Generally speaking, embodiments of the invention comprise light source control means configured to control the light sources to illuminate the conveying paths independently in a conveying path illumination order and camera control means configured to image the articles conveyed along the conveying paths in that order, i.e. as the paths are illuminated. Any suitable control means may be used and the invention is not limited to the manner in which the light sources and cameras are controlled. In some embodiments, the control means for each light source and/or each camera may be embodied in the same control device. Alternatively, the operation of either each camera or each light source may trigger operation of the corresponding light source or camera respectively.
In other embodiments, the number of light sources and/or cameras used may not necessarily correspond to the number of conveying paths to be analysed. The position of a light source / camera, or the light emitted from or incident on said light source / camera may be controlled in order to illuminate or image two conveying paths using the same light source or camera, for example. Alternatively a conveying path may be illuminated and/or imaged by two or more light sources and/or cameras respectively. Multiple types of light sources
In some embodiments the sorting system is configured to illuminate each conveying path with more than one type of light. This may be achieved using a number of light sources able to illuminate each conveying path or using a single light source for each conveying path that is able to illuminate the conveying path with more than one type of light. The types of light may include different parts of the electromagnetic spectrum (i.e. light of certain wavelength ranges such as ultra-violet, infra-red, red, green, blue, etc) or light having other qualities such as having an even distribution of brightness across a region or originating from a particular position (e.g. highly directional light) or a light that is projected in a pattern.
Each conveying path is illuminated by each type of light independently and images are captured when articles on the conveying paths are illuminated. There may be a sequential or nonsequential ordering of illumination by each light type, or light type illumination order. The ordered illumination of conveying paths may occur by conveying path and then by light source or vice versa.
To illustrate these two options, in one example, a sorting system has conveying paths P1 to P4. Cameras C1 to C4 are each positioned to image articles on the correspondingly numbered conveying path. Each conveying path can be illuminated by light types A, B and C such that light types L1A, L1 B and L1C illuminate articles on path P1 , and so on. Light types A, B and C may be generated by three different light sources or they may be generated by the same light source that is able to alter the type of light it generates, for example filters. In one option the light source and cameras are controlled to illuminate and image the articles in the following order: L1A-C1 , L1 B-C1 , L1 C-C1 , L2A-C2, L2B-C2, L2C-C2, L3A-C3 and so on. In another option the order may be: L1A-C1 , L2A-C2, L3A-C3, L4A-C4, L1 B-C1 , L2B-C2, and so on. In both of these examples both the conveying path illumination order and the light type illumination order is sequential. However, in other embodiments, one or both of the conveying path illumination order and the light type illumination order is non-sequential and determined based on factors such as the detection of articles on the respective conveying paths and the type of articles detected in order to decide the ordering of the illumination by conveying path and by light type. Simultaneous illumination / capture
In some embodiments of the invention, some of the conveying paths are illuminated and imaged simultaneously, or part of the image capture time of at least two lanes may overlap. This may occur, for example, where two conveying paths are positioned sufficiently far apart that light from a light source incident on one of the conveying paths does not illuminate another conveying path, or the light source does not interfere sufficiently with another conveying path to substantially alter the quality of image data captured from the other conveying path. This may enable higher rates of sorting to be achieved in sorting systems with large numbers of conveyors where, if images of more than one lane of articles could not be captured
simultaneously, the conveyors would need to be slowed to rates below the desired article processing rate. It may also enable the light sources to be driven at higher currents, which may result in a higher light output with less heat dissipation and lower overall power consumption than could otherwise be achieved.
In another embodiment, simultaneous illumination of two areas of a single conveying path may occur, with the two illuminated areas being separated by a sufficient longitudinal distance that interference between the respective light sources is minimised or reduced to a tolerable level.
Exemplary system according to an embodiment of the invention
An exemplary control system will now be described with reference to Figure 2, which is a schematic illustration of an article analysis system 20 according to one embodiment of the invention.
Analysis system 20 comprises a number of lanes 21 along which articles are conveyed. Articles in each lane are able to be illuminated by lane lighting systems 22, which include one or more light sources which may take the form of one or more LED light assemblies or any other form of lighting. The light from the LED assemblies may be focussed at a region in the respective conveying lane 21 using a plano-convex lens. The light may also be polarised using, for example, a polariser across the lens.
Articles in each lane are able to be imaged by one or more cameras 23. The cameras 23 for each lane may include a master camera and 'slave' cameras. One of the cameras 23 generates a synchronising pulse signal from which the timing of activation of the other cameras 23 and LEDs in lane lighting systems 22 is taken. In the embodiment of Figure 2, the camera that generates the synchronising pulse signal (which may be referred to as the 'system master' camera) does not have sufficient power to output a strong enough pulse signal to synchronise all the other slave cameras and LEDs directly so camera synchronisation buffers 26 are used - one for each lane master camera 23. The camera synchronisation buffers 26 receive the synchronisation pulse outputted by the system master camera and buffer the pulse to boost its power, thus allowing it to synchronise the cameras and LEDs in a number of lanes from a single master camera.
In some embodiments of the invention, camera synchronisation hubs may be connected between the camera synchronisation buffers 26 and the slave cameras 24. The hubs join up the appropriate synchronisation signals between the cameras 24 and may also power the cameras 24 via the same cable. No power sources are illustrated in Figure 2 but it will be apparent to the skilled addressee how power can be supplied to the components of the article analysis system 20.
The synchronisation pulse generated by the master camera is supplied by the camera synchronisation buffers 26 to lane lighting systems 28. Each lane lighting system comprises one or more light sources, for example LED assemblies and may further comprise drivers for controlling activation of the light sources. In one embodiment, for example, there is one smart LED driver 28 per conveying lane or path. Based on the timing of the synchronisation pulse signal received, the drivers activate the LEDs 22 for that lane using a pulsed current signal. The illumination time of each 'flash' of an LED is configurable, as is the time delay between flashes for each LED. The current and/or power of the LEDs may also be configurable. Furthermore, the nature of the LEDs illuminated in each LED assembly or array may be configurable to aid grading performance depending on the nature of the article being sorted or the characteristic of the article that is to be determined. For example, an LED assembly may comprise both white and infra-red lights and the type of light illuminated in order to image the articles may be selected to optimise (or at least increase) grading. These LED settings may be configured from software running on a computing device 201 or other processor controlling operation of the article analysis system 20 or components thereof. The timing of illumination of the LEDs is set so that they are only illuminated when the respective cameras 23/24 are imaging the articles on the respective conveying lane 21 . This saves power and reduces the delay necessary between imaging lanes. One or more computing or processing devices 201 , such as a PC or other computer, are coupled within the system and are operable to control operation of the system. In the embodiment of Figure 2, computer 201 is connected to the lane lighting systems 28 and cameras 23. Connection of the computer 201 to the components of the system may be as shown in Figure 2 or in any other manner, for example through direct connection of the computer 201 to each component, or a combination of direct and indirect connections. The computers 201 may be configured to run software with which the system can be controlled. In addition, images of the conveyed articles taken by cameras 23/24 are provided to the computers where suitable image processing software is used to analyse the images of the articles in order to determine characteristics of them and to determine how the articles should be sorted (i.e. grading).
In some embodiments the system comprises switches, for example connected between the cameras and computing device / processor to enable the computing device / processor to control and communicate with each camera individually.
In one embodiment of the invention, the LEDs and cameras are all mounted above the conveying lanes on a supporting framework or cabinet.
Embodiments of the invention have been found to dramatically improve performance compared to conventional sorting systems when grading fruit.
Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".
The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference. Reference to any prior art in this specification is not, and should not be taken as, an
acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world. The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.
Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.
It should be noted that various changes and modifications to the presently preferred
embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention.

Claims

Claims
An article sorting system comprising:
one or more endless article conveyors configured to convey articles along a plurality of adjacent conveying paths;
at least one light source positioned to illuminate the conveying paths;
at least one camera positioned to image articles conveyed along the conveying paths;
light source control means for controlling the at least one light source to independently illuminate each conveying path in a conveying path illumination order; camera control means for controlling the at least one camera to image the articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources; and
discharge means for selectively discharging articles from the article conveyors to one or more discharge locations.
An article sorting system as claimed in claim 1 , wherein the light source control means and camera control means are configured to illuminate and image at least a first article on a first conveying path followed by at least a second article on a second conveying path, and so on to sequentially illuminate and image at least an article on each conveying path before illuminating and imaging further articles on the conveying paths, sequentially by conveying path.
An article sorting system as claimed in any one of the preceding claims, wherein the at least one light source is configured to illuminate the conveying paths with multiple types of light.
An article sorting system as claimed in claim 3, wherein the system comprises a plurality of light sources, each configured to illuminate the conveying paths with a different type of light.
An article sorting system as claimed in claim 3 or 4, wherein the light source control means is configured to independently illuminate articles on each conveying path with each type of light in a light type illumination order.
An article sorting system as claimed in any one of the preceding claims, wherein the light source control means and camera control means are configured to illuminate and image at least two of the articles simultaneously.
An article sorting system as claimed in claim 6, wherein said at least two of the articles are sufficiently spaced apart when illuminated and imaged to substantially avoid light interference from the light sources between said articles.
An article sorting system as claimed in claim 7, wherein said at least two articles are conveyed on different conveying paths, said different conveying paths being sufficiently spaced apart to substantially avoid light interference from the light sources between said different conveying paths.
An article sorting system as claimed in any one of the preceding claims, wherein the sorting system comprises means for generating a synchronising pulse signal to synchronise illumination of the at least one light source and imaging by the at least one camera.
An article sorting system as claimed in any one of the preceding claims, wherein the at least one light source illuminates the articles substantially only when the at least one camera images the articles.
A computer-implemented method of imaging articles on a conveying system comprising: controlling at least one light source to independently illuminate a plurality of adjacent conveying paths in a conveying path illumination order; and
controlling at least one camera to image articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources.
A method as claimed in claim 11 , wherein the method comprises controlling the at least one light source and the at least one camera to illuminate and image at least a first article on a first conveying path followed by at least a second article on a second conveying path, and so on to sequentially illuminate and image at least an article on each conveying path before illuminating and imaging further articles on the conveying paths, sequentially by conveying path.
13. A method as claimed in claim 1 1 or 12, wherein the method comprises controlling the at least one light source to illuminate the conveying paths with multiple types of light.
14. A method as claimed in claim 13, wherein the method comprises controlling a plurality of light sources to each sequentially illuminate the conveying paths with a different type of light.
15. A method as claimed in claim 12 or 13, wherein the method comprises controlling the at least one light source to independently illuminate articles on each conveying path with each type of light in a light type illumination order.
16. A method as claimed in any one of claims 1 1-15, wherein the method comprises
controlling the at least one light source and the at least one camera to illuminate and image at least two of the articles simultaneously.
17. A method as claimed in claim 16, wherein said at least two of the articles are sufficiently spaced apart when illuminated and imaged to substantially avoid light interference from the light sources between said articles.
18. A method as claimed in claim 17, wherein said at least two articles are conveyed on different conveying paths, said different conveying paths being sufficiently spaced apart to substantially avoid light interference from the light sources between said different conveying paths.
19. A method as claimed in any one of claims 11-18, wherein the method comprises
generating a synchronising pulse signal to synchronise illumination of the at least one light source and imaging by the at least one camera.
20. A method as claimed in any one of claims 11-19, wherein the method comprises
controlling the at least one light source to illuminate the articles substantially only when the at least one camera images the articles.
21. An apparatus for imaging articles on a conveying system comprising:
means for controlling at least one light source to independently illuminate a plurality of adjacent conveying paths in a conveying path illumination order; and
means for controlling at least one camera to image articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources. A computer-implemented method of sorting articles on a conveyor system comprising: controlling at least one light source to independently illuminate a plurality of adjacent conveying paths in a conveying path illumination order;
controlling at least one camera to image articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources;
receiving data indicative of how an inspected one of the articles should be sorted based on a characteristic of the inspected article; and
controlling actuation of article discharge means in order to discharge the inspected article from the respective conveying path dependent on the data indicative of how the inspected article should be sorted.
A method as claimed in claim 22, wherein the method comprises controlling the article discharge means based on analysis of images captured by the at least one camera.
A method as claimed in claim 23, wherein the method comprises generating data indicative of how the articles should be sorted dependent on the analysis of the images.
A method as claimed in any one of claims 22-24, wherein the method comprises receiving image data based on the images and analysing the image data to determine characteristics of the imaged articles.
An apparatus for imaging articles on a conveying system comprising:
means for controlling at least one light source to independently illuminate a plurality of adjacent conveying paths in a conveying path illumination order;
means for controlling at least one camera to image articles conveyed along the conveying paths when the respective conveying paths are illuminated by at least one of the light sources;
means for receiving data indicative of how an inspected one of the articles should be sorted based on a characteristic of the inspected article; and
means for controlling actuation of article discharge means in order to discharge the inspected article from the respective conveying path dependent on the data indicative of how the inspected article should be sorted.
PCT/NZ2014/000155 2014-07-31 2014-07-31 Article sorting system with synchronised lane detection WO2016018157A1 (en)

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