WO2017135845A1 - Method of sorting objects by shape and device for the implementation thereof - Google Patents

Abstract

The invention relates to methods of sorting different objects into a limited number of classes according to their shape. The main use of the invention is in processes for sorting (grading) precious stones, primarily diamonds, by shape. The present method of sorting objects by shape consists in feeding objects one-by-one in a free-fall phase into an illumination and examination zone, generating an image of the objects in the light of light sources by means of electronic image generating devices paired with said light sources, processing the resulting images using a computing device with the aim of putting the shape of an object into one of a number of predetermined classes of shapes, and generating a command to a sorting device, which places the object into the appropriate storage bin for its size. The illumination of the object in the illumination and examination zone and the generation of an image of the shape of the object are carried out by the consecutive activation of each individual pair of illuminating devices and image generating devices as the object is on a free-fall trajectory in the illumination and examination zone. The not less than eight pairs of illuminating devices and image generating devices are all arranged in different planes equidistantly about a sphere around the point at which the free-fall trajectory of the object intersects the optical axes of the pairs of illuminating devices and image generating devices. The technical result is a method of sorting objects by classes of shapes which is highly efficient and also reduces the degree of classification error, which in turn reduces the number of objects that need to be resorted or manually processed.

Description

 METHOD FOR SORTING OBJECTS BY FORM AND DEVICE FOR ITS IMPLEMENTATION

Technical field

 The invention relates to methods for sorting various objects into a limited number of classes in accordance with their form. The invention finds its main application for the processes of sorting (sorting out) precious stones by their shape, primarily diamonds and for devices carrying them out.

 State of the art

 Known methods for sorting objects by shape and other signs are based on the following general principles: organizing the transportation of a sequence of objects with a special device through the observation zone, lighting individually each object passing through the observation zone, obtaining an image of the object’s shape or the reaction of the object to lighting in the registration device, pre-processing and conversion the received image (signal) in digital form, the analysis of the information thus obtained in the computing device triad for compliance with a predetermined system of parameters that determine whether an object belongs to a certain class, making a decision and issuing a command to the actuator to move the object to the appropriate bunker - the drive of objects of one of the classes according to the selected classification.

So, there is a known installation for the automatic classification of crystalline objects (for example, rough diamonds) by color or purity (US Patent NQ 4,951, 825, IPC ⁵ В07С 5/342, В07С 5/36, publ. 08/28/1990), in which the conveying device implemented as a combination of a vibratory feeder and a rotary conveyor with a vacuum gripper system. The installation has a lighting zone and observations, including illuminators and devices for recording images of objects, as well as a drive of objects with the corresponding classification accepted by the number of drive compartments. Installation works as follows. The vibrator feeds the objects from the total unclassified mass into a sequence, one after the other. A rotary conveyor delivers piecewise classified objects to the lighting and observation zone, where, by means of illuminators and radiation detectors that have passed (reflected) through (from) object (a), information is received for making a classification decision. Then, the same rotary conveyor delivers the object to the sorting device, which, upon the command of the computing device, places the object in the drive compartment corresponding to the object class. The limitations of the described installation are obvious if the classifying feature is the shape of objects, for example, the shape of crystals of rough diamonds. A comprehensive analysis of the form would require an increase in the number of recording devices (cameras) in the observation zone, while part of the object in the vacuum unit remains inaccessible for observation.

In the sorting device (RF Patent N ° 2016672, IPC ⁵

B07C 5/342, G01 N 21/87, publ. 07/30/1994) an attempt was made by complicating the design of the vacuum rotor conveyor to provide the necessary representativeness of the data of the monitoring system due to the means of rotation of the object (crystal) around its axis when passing the field of view of the optical measuring system. The described installation is applicable to sorting objects by form. Nevertheless, the fundamental drawback of the conveying system based on the rotor conveyor - the lack of visibility from the side of the vacuum attachment unit of the crystal has not been overcome. Another disadvantage of the described devices and implemented by them Ways is insufficient performance, less than 5 - 10 objects per second.

 A device for sorting diamond crystals is known (RF Patent Ns 2424859, IPC V07C 5/342 (2006.01), published July 27, 2018 1), which has a unit for supplying units of objects and a horizontal conveying disk. In this installation, there are lighting and observation equipment, a control computing device and a sorting unit for placing crystals in bins in accordance with classification criteria. Illumination of objects, obtaining information about the form is carried out on a horizontal transporting disk. The control computing device analyzes the information received and issues a command to the sorting unit to place the crystal in the hopper corresponding to its classified form. The disadvantages of this technical solution are low productivity, an incomplete overview of the crystal surface, possible violations of the rhythm of the flow of crystals into the observation zone.

The solution to combine the requirements of high performance with the full representativeness of the viewing directions of the object is to analyze its shape in the free fall phase. A known method and device for sorting objects by shape. (U.S. Patent No. 5,184,732, IPC ⁵ B07C 5/342, published 09/02/1993). According to the method, each classified object is sent to the observation zone in the free fall phase. In the observation zone in one plane perpendicular to the direction of incidence, there are, as a rule, several lighting and observation devices that capture an instant picture of the profile (silhouette) of an object by each of the observation devices. During the flight of an object from the observation zone to the underlying sorting zone, a computing device based on a hierarchical algorithm sets the object to belong to one of the classes of the form. For example, for rough diamonds, it can be 16 different classes.

 The aforementioned device also discloses the essence of the apparatus for sorting crystalline objects in a form that includes an observation zone for objects freely falling through it. In this zone, there are devices for illuminating objects and devices for acquiring images of objects for subsequent processing according to a hierarchical algorithm to obtain a classification decision regarding the belonging of an object that has passed the observation zone to a particular form class. The installation provides for a node for sorting classified objects by shape with corresponding storage bins for each class. The productivity of such a device reaches 10 crystals per second or more, up to 20. At the same time, the sorting quality, defined as the percentage of crystals to be manually sorted after the installation works out of their total number, was low, about 30 for crystals from 1/15 to 4 carat.

The main disadvantage of the described method and device is the relatively high proportion of crystals that are not automatically classified and must be manually sorted. Classification errors are caused by both the hardware implementation of the method and the algorithm of the process of identifying the class of the form implemented by the computing device. So, the location of the illuminators and the recording cameras in one plane and the processing of the image of a passing object obtained at one time for all recording devices does not fundamentally exclude identification errors due to an accidental instantaneous location of the object when the shape silhouette falls at the time of registration. The increase in the number of illuminators and co-located recording devices (cameras) is limited by design and does not result in to a proportional decrease in the probability of identification errors, also due to an increase in the array of processed data.

 A device and method for checking precious stones (application PCT / EP2013 / 055165 "GEMSTONE INSPECTION), applicant DE BEERS CENTENARY AG, priority date 16.03.2012). The device comprises a vacuum nozzle for extracting precious stones from the feed set, having a central channel for supplying vacuum, made of a transparent material for measuring the optical properties of the stone, as well as with the possibility of manipulation to change the orientation of the gem; a transporting mechanism rotating around the hub and containing many nozzles for transporting the gem held by it to the measurement site, a measuring system, a control system associated with a vacuum nozzle and a measuring system to ensure that the gemstone arrives at the measurement site at a specific time, a positive pressure application system for separating the gem from the nozzle in the drop zone.

 The method for sorting gems implemented by the apparatus is based on extracting crystalline objects from the supplied set, measuring the properties of the gem supplied and held by a moving vacuum nozzle at one or more measurement sites, or when it is freely falling, and feeding the gem into a container selected from many containers depending on the measured properties.

In the proposed method for sorting precious stones in one of the measuring devices, a collimated light source and observation means are used so that the gem held by the nozzle passes between the light source and observation means to form a series of images of each stone with the further construction of a 3D model of the stone’s shape from a series of images. Picture formed at different angles with respect to the light source. The disadvantage of this sorting method is the presence of glare in the means of observation and, accordingly, the fuzzy formation of the image of the stone in connection with the location of the light source, the means of observation and the simultaneous formation of images by all measuring instruments, which leads to an increase in the identification errors of the shape of the stone and an increase in the share of unclassified objects.

 In another embodiment, the measuring device presents a diffuse light source and an array of cameras in various places, including the bottom of the stone, as well as means for rotating the nozzle holding the stone around its axis to identify the color of the stone.

 One of the measuring devices contains a spectrometer for determining the photoluminescence spectrum of the stone.

 All the devices described above in this source and the methods implemented on their basis determine the classification characteristics of the gem held by the nozzle and, accordingly, they have the same disadvantages that were mentioned above, namely the impossibility of obtaining an image of the full shape of the object and an increased proportion of erroneously classified crystals. In the description of the present invention mentioned, but not disclosed, a method and apparatus for determining the classification features of a gemstone, for example, the form in which this process occurs in the free fall phase. Thus, the main disadvantage of the described method and device is the low sorting performance, which has not been overcome.

A device for sorting raw materials is known "Sorting aggregate material)) (International application PCT / EP2013 / 055240, applicant" DE BEERS CENTENARY AG, priority date 03.16.2012, published 09.19.2013), we selected as a prototype, having a transport system for individually transporting a crystalline object to a measurement site, including a rotating carousel, on which a stone is held using a vacuum nozzle; a measuring system that determines the properties of an object, typically a diamond held by a nozzle, such as: identification of diamond, quality of diamond and its shape; and also a switchgear for guiding the gem from the transport system to one of the plurality of cells.

 The measuring system for determining the shape of a gemstone contains many cameras located in relation to the measurement point (observation) in the same plane in a circle or in a sphere, while the transport system feeds and rotates the classified gemstone to the measurement point (observation).

 The transport system moves the gem from the measurement (observation) point to the second level, at which the stone is dumped into a specific cell, depending on the classification decision made, using a multi-pass carousel of the first and second levels.

 In this method of sorting crystalline objects (precious stones) by shape during measurement, the object is held by a nozzle, which, in principle, can lead to identification errors due to the incompleteness of the observed silhouette of the gem, and also limits the speed of sorting objects by shape.

These problems can be solved using the claimed invention. Disclosure of invention

 The objective of the proposed technical solution is to develop a method and device that provides high performance sorting objects by shape.

 The technical result of the invention is expressed in ensuring high performance of the method for sorting objects by form classes while reducing the percentage of classification errors expressed in the number of objects to be repeated or manually sorted.

 The technical result of the invention is achieved by the fact that in the proposed method for sorting objects in accordance with their shape, which includes the piecewise supply of objects to the lighting-observation zone in the free fall phase, obtaining images of objects in the radiation of illuminators from at least eight electronic image forming devices, processing received images with the aim of assigning the shape of the object to one of the predefined classes of the form, the formation of the team on the Executive sorting device that places the volume t in the storage hopper corresponding to its shape, the following action has been additionally introduced: illumination of the object in the observation zone and image formation of its shape is carried out by sequentially switching on each individual pair “illuminator - image forming device”, from the first to the eighth, when the object is on the free fall path in the lighting-observation zone.

It is preferable to perform as imaging devices high-speed electronic cameras having the ability to pre-process the image to highlight the shape profile of the object directly in the camera processor. The problem is also solved by the fact that in the device for implementing the method of sorting objects according to a form consisting of a node for generating a sequence and supplying objects, a lighting and observation zone, a sorting zone and a computing device that processes images of classified objects flying through the observation zone, the following location is additionally introduced pairs “illuminator - imaging device”: no less than eight pairs of “illuminator - imaging device” are located in different planes and uniformly in a sphere around the point of intersection of the trajectory of free fall of the object and the optical axes of the pairs “illuminator - image forming device”.

The image formation process begins at the command of the first sensor of the presence of the object located at the entrance of the object to the lighting-observation zone. The object is in a free fall phase. Further, each separate pair of “illuminator - imaging device” is switched on sequentially from the first to the last during the time while the object is in the lighting-observation zone.

 When imaging, not less than eight pairs of “illuminator - imaging device” are used. Illuminators and imaging devices are synchronized in pairs. The illuminators are emitted in the infrared range to obtain maximum image contrast.

To increase the contrast of the image in electronic image forming devices, preliminary digital processing of the obtained image of the profile of the object is carried out. A device for sorting by shape consists of a piece-by-piece object feeding onto the path of a free fall of a node including rotary vacuum conveyor and two vibratory feeders, lighting zones - observations, sorting zones with storage bins and a computing device for processing the resulting images of object shapes.

The sorting device is characterized in that the illuminators and image forming devices are located in different planes around a portion of the object’s path of free fall and at different angles with respect to the path of the object’s fall, which allows obtaining the most complete information about the object, forming the image of the object and reducing the number of classification errors. In this case, the registration of images of each flying object is carried out by the sequential process of switching on the pair of illuminator - image forming device while the object is in the observation zone, which allows to eliminate glare from neighboring illuminators, optimize the processing time of the received images, which also reduces the number of classification errors and, accordingly, increases productivity sorting process.

 Brief Description of the Drawings

 The figure shows a block diagram of the proposed device.

1 - vacuum rotary feed conveyor of objects;

 2 - a large vibratory feeder forming a sequence of objects;

3 - small vibratory feeder;

 4 - sensor entrance of the object into the lighting zone - observation;

 5 - device for recording images of objects (camera);

 6 - LED illuminators of objects;

 7 - sensor input of the object into the sorting zone;

8 - buffer drum - drive with cells;

9 - bunker - drive by object shape classes 10 - pneumatic shutoffs of objects in their respective form of the hopper - drive.

 Preferred Embodiment

 A method for sorting objects by shape consists in feeding objects to a free fall path, passing an illumination-observation zone by an object, turning on each separate pair “illuminator - image forming device”, forming images of objects, processing the resulting images of object shapes by a computing device, passing the sorting zone with storage bins.

A device that implements the proposed method consists of a feed unit, consisting of a vacuum rotary feed conveyor of objects 1 and two vibratory feeders, forming a sequence of objects - a large vibratory feeder 2 and a small vibratory feeder 3, which provides a uniform, adjustable and reproducible flow of classified objects into the lighting-observation zone along the trajectory of free fall. At the object’s entrance to the lighting-observation zone, the first optoelectronic sensor for entering the object into the lighting zone - observation 4 is installed, which starts the synchronized process of sequential shooting of the object with each camera 5. The object is illuminated by LED illuminators of the objects 6 in the infrared range to obtain the maximum contrast image. LED illuminators 6 provide a high-quality image by the camera 5 at the point of the trajectory of free fall of the object in the lighting-observation zone, are switched on sequentially and synchronously. In addition to optimizing the processing time, sequential shooting avoids distorting images of glare in the camera from neighboring illuminators. In addition, the microprocessor of electronic cameras performs preliminary digital processing of the received image profile of the object to increase contrast. The reception of this pre-processed information about the shape of an object in the form of digital images by a computing device starts from the moment information is received from the first camera and ends after the image is received last. Further, the object is identified by a certain class of form or a decision is made about the impossibility of classifying the shape of the object. Having passed the lighting-observation zone, the object before entering the cut-off zone is registered by the second optoelectronic sensor entering the object into the sorting zone 7. The cut-off zone consists of a rotating buffer drum - a storage unit with cells 8, a number of pneumatic cutoffs 10 and storage bins 9 for objects sorted by shape . After passing the second optoelectronic sensor entering the object into the sorting zone 7, the object enters one of the cells of the buffer drum 8, the number of which is transmitted to the computing device. By the time the cell reaches the deflection position by pneumatic shutoffs 10, the computing device identifies the object to be classified by one of the classes in shape, after which it moves by pneumatic pulse of cutter 10 into the storage hopper 9 of the corresponding shape class.

Distinctive features of the described sorting method, namely, the sequential process of obtaining an image of the shape of an object at a point of the lighting-observation zone and the location of illuminators and recording cameras in a sphere, reduce the share of unclassified objects in their total number by reducing the likelihood of identification errors. The sequential transmission of the obtained images of the object in the process of its being in the lighting-observation zone allows for high processing performance of objects when maintaining the share of unclassified below (5 - 10)% of their total number.

 Examples of practical implementation of the method and device

An example of the practical implementation of the proposed method and device can serve as a plant for sorting rough diamonds in the form of USA-1, ASA-2F. These plants are used for sorting rough diamonds in industrial conditions. Tests of the installation when sorting into 10 classes according to the shape of the raw material with a particle size of (- 6 + 1, 5) mm showed a productivity of 10 crystals per second. The share of unidentified crystals for re-sorting was less than 10% of the total number of past sorting.

Industrial applicability

 The method of sorting objects by shape and a device for its implementation allows to ensure high performance of sorting objects by class of form, reduce the number of classification errors and can be used to sort (sort) gems according to their shape.

Claims

Claim  1. A method for sorting objects in accordance with their shape, including the piecewise supply of objects to the lighting zone — observations in the free fall phase, obtaining images of objects in the radiation of illuminators from at least eight electronic image forming devices, processing the obtained images in order to assign the shape of the object to one of the predefined classes of the form, the formation of the team on the Executive sorting device, placing the object in the appropriate form of the hopper - drive, characterized in that o to increase the performance of sorting and reduce the number of classification errors, the illumination of an object in the observation zone and the formation of an image of its shape is carried out by sequentially turning on each individual pair of “illuminator - image forming device”, from the first to the eighth, when the object is on the free fall path in the lighting zone - observations.  2. The method of sorting objects in accordance with their shape according to paragraph 1, in which high-speed electronic cameras are used as image forming devices with preliminary image processing by extracting the shape profile of the object directly in the camera processor, before transferring the image for processing in a personal computer. 3. A device for implementing the method for sorting objects according to the form of claim 1, consisting of a node for generating a sequence and supplying objects, a lighting and observation zone, a sorting zone, and a computing device that processes images of classified objects flying through the observation zone, characterized in that each of less than eight pairs of “illuminator - device forming images ”are located in different planes and uniformly in a sphere around the point of intersection of the trajectory of free fall of the object and the optical axes of the pairs“ illuminator - image forming device ”.