CONTAINER POSIONNING SYSTEM AND METHOD

Technical field

The present invention relates to a container positioning system and method which are particularly suitable for use within labelling machines to locate an identifying element on a container so as to be able to position the said container in a very precise arrangement for the subsequent step consisting of the application of a label that must be affixed in a well-defined area on the container.

Background Art

As is known, a labelling machine comprises several stations such as the station designated for transporting the containers that arrive at a positioning station, where the said containers are rotated so as to be aligned and placed in a predetermined position, to then be sent on to the next station where the label is applied.

The positioning station includes a carousel equipped with a plurality of discs, each of which is designed to house a container and a device to rotate the container on itself and hold the said container in a precise arrangement so as to arrive at the labelling station correctly positioned and receive the label in the right position.

In particular, the positioning systems currently in use can be mechanical or optical. The former are now obsolete while the optical systems envisage, in some cases, the use of sensors, but these too have led to problems in terms of precision and above all setting difficulties every time the container format is changed, while other optical systems envisage the use of cameras, lighting devices, mirrors, etc. and they are the ones which are used preferentially nowadays.

Positioning and viewing systems have been known and used in the labelling machine industry for some time and comprise a rotating carousel with a plurality of seats and a container viewing system composed of at least one lighting device and, one, two. or more cameras and image management means, however what differs is how these components work.

The Applicant is aware of Italian patent n.1383597. which describes a system for detecting and angularly positioning containers in labelling machines comprising a rotating carousel for moving the containers, wherein the said carousel is equipped with a plurality of motorised discs which support and move the containers . The system also includes four optical means for acquiring images, which are controlled in such a way as to acquire a set of four images which reproduce the image of the container along the entire perimeter thereof.

The optical means are cameras arranged geometrically at the vertices of a square and oriented so as to be mutually facing in pairs along the diagonals of the square. These cameras arc housed in pairs inside housings located inside and outside the carousel.

The housings are arranged in such a way that each container, during its journey around the periphery of the carousel, crosses the intersection of the diagonals joining the pairs of cameras.

Lighting means are positioned at each camera to illuminate the field of view thereof, along the diagonals joining the said cameras.

A photocell is positioned on the vertical axis that runs through the intersection of the diagonals joining the cameras, in an elevated position with respect to the container, so as to detect whether the container is present and in the correct position. The four cameras with the lighting devices and the photocell are operationally connected to a control and monitoring unit, which, through appropriate software, operates the system.

The container features an identifying element which is used to ensure the correct alignment of the container on the disc.

The system software manages the positioning of the container on the disc, through the camera images, so that the said container is rotated until the identifying element is positioned in a predetermined way. The aforesaid system operates with four cameras so as to cover the entire perimeter of the container and the number of cameras corresponds with the number of images.

One problem encountered by the aforesaid system arises from the fact that, since the container has to be viewed by 360° with only four images, a considerable amount of space is necessary in order to house the cameras correctly and since two thereof must be placed on the carousel it is indispensable for the carousel to have a considerable diameter, resulting in installation costs and the occupation of a considerable amount of space in the industrial shed.

The Applicant is aware of patent DE 10201 1 083377A1. which describes a container positioning device which includes a rotating carousel equipped with a multitude of seats, each one of which is suitable to house a container. In more detail, each seat is designed to rotate around its own axis to transmit a rotary motion to the container located in the seat, so as to allow the said container to be viewed by a viewing system consisting of a lighting device, designed to illuminate the container, in such a way that the image capture device can capture a sequence of images of the container during the rotary movement thereof.

The carousel features an angular position of each seat and means for synchronising the images captured and the angular positions of the carousel and the container seats.

In addition, the image capture device is equipped with a pair of cameras positioned one after the other along the pathway travelled by the containers. The viewing system is based on the principle that the lighting device provides the container with a predetermined reflection which is captured by the two cameras at different angles with respect to the central axis of the container. Depending on the image capture angle, the lighting device produces a different reflection on the reference element on the container. The reference element, as captured from two different angles, projects a different image according to different parameters. The container is detected by two cameras at two different rotation angles and a single reference element is detected at the same time by the two cameras from different angles. The system envisages obtaining two different images of the reference element since the cameras are focussed on a common image capture area. The two images are processed so as to reconstruct a virtual image of the container which will be used to manage the positioning of the container based on the reference element.

One drawback encountered with the system just described is due to the fact that two cameras arc needed to film the same portion of the container. The two cameras focus on a common area and this arrangement requires the occupation of significant space, which limits the locations of the labelling stations.

Another drawback derives from the fact that, when the image of the container is obtained from a pair of images taken from different angles, the said image is misaligned, which means it is not certain that it will be possible to detect the identifying element with precision.

The Applicant is also aware of Italian patent n.102016000037465, which describes a device for container positioning and quality control which has a rotating carousel with a plurality of seats around the circumference of the said carousel. Each seat rotates around its own axis to transmit rotary motion to the container placed in the seat. The carousel features an area for the optical reconstruction of the characteristics of each of the containers based on the acquisition of multiple images from a single viewing point. An appropriately arranged lighting device allows images to be obtained containing information about the lateral surface of the containers.

Management and synchronisation means are envisaged for joining the images to complete the reconstruction of the container for the positioning or quality control thereof. The aforesaid system envisages that an image is captured for each position and for each view. Every situation is memorised. In each seat, the position and the graphic motif in question are stored. The system is designed to learn the graphic, angular, and volumetric characteristics of the container to be positioned via images captured at each angular section, according to the number of images captured in each seat during the format creation process. Each angle is associated with an image, which is why it is necessary to map the container in order to set machine operation.

In each position the machine stops and the system takes a photo of the container in order to learn the position of the identifying element in each angular sector of the container and the resolution depends on the number of images planned.

Evidently, capturing the entire container requires a considerable number of images and during the production method, this arrangement results in considerable amounts of time for the creation of the format. Furthermore, the machine stops at each step so it takes a long time to learn the data. if the set of instructions created are not validated for any reason, it must all be repeated.

An image library is created for each situation.

The system described has highlighted a drawback which emerges from the fact that the image acquisition method is based on the camera capturing images of a series of angular sectors of the container in sequence and then the management means processing the plurality of views by partially overlapping the images of the views to obtain an optical reconstruction of the entire container. T'his reconstruction will make it possible to then position the said container.

With the aforesaid system there is a laborious job of acquiring preliminary data on the container, which lengthens preparation times.

Another drawback noted emerges from the fact that, if the container parameters are not set perfectly, that type of container will not be labelled comectly and all the subsequent times that the said format is put into the machine, the same errors will be repeated, leading to poor production results.

The Applicant is also aware of Italian patent 11.102019000017672, which describes a container positioning device and method comprising a carousel rotating around its own vertical axis, which has a plurality of seats circumferentially, each seat rotating around its own axis to transmit to each container housed therein a rotary motion around its own vertical axis and a further rotary movement with the rotating carousel, a fixed lighting device for lighting up the container and a single fixed device for capturing multiple sequential images of the container during the further rotary movement. The image capture device includes electronic management means presenting learning means, validation means, and processing means operating reciprocally in a temporal sequence wherein the learning means are suitable for carrying out a step to acquire information about the entire lateral surface of the container in a number N of positions within the field of view framed by the image capture device in which, when the carousel is stationary, for each information acquisition step in each of the N positions, the container is positioned with a random initial positioning, and during a 360° rotation around its own axis, a number R of images of the container with the carousel stationary is acquired. The validation means are envisaged to perform a validation step in which the electronic management means acquire, from the image capture device, a single current image of the container in each position N. The electronic management means apply a similarity function between each current image Ni and the R images captured in the same position N during the learning step, aligning and summing the similarity functions. The processing means which are active during the carousel rotation (during which step, for each container, the electronic management means acquire, from the image capture device, a single current image in each position N) apply a similarity function between each current image Ni and the R images captured in the same position N during the learning step, and calculate and sum the similarity functions: the angle am, corresponding to the maximum value of this sum, is used for positioning the container. The problems mentioned for the aforesaid patent are also found with this system.

While allowing a container to be oriented and positioned in a predetermined manner to allow the subsequent positioning of a label, the systems described in the aforesaid patents have highlighted problems that limit the operation thereof as described above.

Disclosure of Invention

The object of the present invention is essentially to solve the problems of the prior art by overcoming the drawbacks described above by means of a container positioning system and method capable of calibrating the space within which a container will travel and creating a map of the pathway which the container will follow.

A second object of the present invention is to create a container positioning system and method capable of suggesting to the machine the space within which movements should be made with respect to the field of view.

A third object of the present invention is to create a container positioning system and method capable of obtaining a machine that is very fast during preliminary operations and very compact, thereby offering the possibility of adding further devices and multiple labelling stations.

A further object of the present invention is to create a container positioning system and method that allows the necessary hardware to be reduced as far as possible with the aim of reducing costs and dimensions while keeping the container format creation times to a minimum.

A still further object of the present invention is to create a container positioning system and method that allows the same approach and hardware to be used to create a machine outfeed station dedicated to quality control of the labelled containers. A yet still further object of the present invention derives from the fact that the container positioning system and method allows time to be saved during the initial parameterisation for each format, thereby allowing the initial procedures of the machine to be automated and hence facilitating use thereof.

A still further but not final object of the present invention is to produce a container positioning system and method which is easy to manufacture and works well.

These and further objects, which will emerge more clearly over the course of the present description, are essentially achieved by means of a container positioning system and method.

Brief Description of Drawings

Further characteristics and advantages will better emerge in the detailed description of a container positioning system and method according to the present invention, provided in the form of a non-limiting example, with reference to the accompanying drawings, in which:

Figure 1 shows, schematically, a container positioning system according to the present invention:

Figure 2 shows, schematically, a component of the positioning system in Figure

Figure 3 shows, schematically, a step in the container positioning method according to the present invention;

Figure 4 shows, schematically, a further step in the container positioning method according to the present invention:

Figure 5 shows, schematically, an element of the system in question.

With reference to the aforesaid figures, and in particular Figure 1. 1 denotes a container positioning system and method as a whole, according to the present invention.

Best Mode for Carrying Out the I nvention fhe system in question can be used in all rotary machines which have servo-assisted discs.

In the present embodiment, the system is combined with a labelling machine in which containers 2 arrive at the positioning station from a conveyor belt and are each positioned on a disc 3 present on a carousel 4 which is rotating.

The positioning system according to the present invention includes a viewing device 5 such as a camera and a lighting device 6 positioned near the camera as shown schematically in Figure 1 .

The viewing device 5 and the lighting device 6 are connected to management and control means 7 which are responsible for managing the rotation of the carousel and the discs and for managing and processing the images transmitted by the camera, in addition to switching on/'off the lighting device.

In the present embodiment, the lighting device 6 features an arched configuration which is concentric to the carousel and is intended to illuminate the container in a constant and uniform manner during the transit motion thereof.

In particular, the arrangement of the camera 5 is directly linked to the sector of the carousel in which the rotary motion of the container will take place, thus also determining the overall dimensions of the positioning system.

In addition to the explanations so far. the camera 5 is located outside the carousel 4 in a specific angular sector predetermined by the management and control means 7. which suggest the arc in which to create the rotary motion of the object to be positioned.

In this analysis sector, the speed of the carousel and the rotation speed of the disc must be coordinated to allow the container to perform a complete revolution in the sector of the carousel determined by the field of view.

In accordance with the present embodiment, the system in question comprises a calibration chart 8. which is placed in the centre of a disc of choice. In more detail, the calibration chart 8 is composed of a plate on whose surface there is a virtual target present, the said target consisting of a line 80 whose task is to provide a reference.

A multitude of points 80a are furthermore depicted on the surface thereof, the said points being arranged according to a specific geometric pattern, wherein the distribution of the reference points comprises predetermined vertical and longitudinal distances between the points. Furthermore, the single reference points also have a predetermined diameter.

The chart 8 is equipped with a support which is designed to engage the chart at one end thereof while at the other end, the said chart is designed to enter a special seat 30 located in the centre of the disc 3.

In the world of artificial viewing and photography, the unit of measurement is the pixel. Now, the system in question must position a container which has specific dimensions in terms of diameter, volume, and height measured using the metric system, therefore the chart is essential to correlate the world of pixels with the metric world.

Indeed, the purpose of the chart is to calibrate the space photographed by the camera and then the space through which the object to be positioned will travel.

During normal operation of the system, a certain number of images must be taken which corresponds to the number of predetermined positions in which the container will be located.

Indeed, the camera 5 is designed to receive an input from the management and control means 7 and capture an image in this way for each input received and the captured images are sent to the management and control means 7 since the camera is connected thereto.

In particular, in addition to the activities already described, the management and control means 7 are responsible for managing the processing of the images captured by the camera, using specific algorithms for the identification of a reference element present on the container and the positioning angle thereof with respect to a predetermined reference for the container.

In addition, the management and control means 7 deal with the human-machine interface for managing the said system, the container formats, and all other system activities such as, for example, language changing, diagnostics, statistics, etc.

The container can be made of glass or PEI' or aluminium and may be cylindrical, conical, quadrangular, or rectangular in shape.

As is known, the container 2 has a reference element 20 present on the surface thereof which is the element which must be located in order to then appropriately rotate the said container by rotating the disc in order to position the container so as to arrive at the label affixing station in a predetermined position and receive the label in the desired position.

As described earlier, the positioning of the camera 5 leads to a certain field of view within which the container will transit during the rotary motion thereof, along which the system will capture a predetermined number of images, each one at a predetermined position on the arc followed by the carousel when transiting in front of the camera and when the disc is rotating about its own axis.

All the components that constitute the positioning station are reciprocally connected and communicate and exchange all the information necessary to guarantee synchronism between the parts (system and machine).

The system envisages that a set of information is acquired and sent to the management and control means and this information consists of: the instantaneous position of the carousel, the position of the individual discs, and the presence or absence of a container

2 on a specific disc. In particular, the positioning system according to the present invention is flexible and able to adapt to the machine. Indeed, depending on where it is positioned on the carousel, the said system suggests to the operator - based on the field of view present with respect to the container framed by the camera - what the container arc of movement should be in order to photograph the said container around 360° during the further rotary motion thereof. It is the system that advises the operator and the said machine as to the peripheral sector of the carousel in which to set the operations to locate the reference element/symbol, thanks to the servo-motorised discs on which the container to be oriented is placed.

In agreement with the present invention, with the components used for the positioning system, it is possible to create a container quality control station (located after the labelling station) which allows a series of elements to be checked, such as: the presence of the label, correctness of the brand, deciphering of codes, and positioning of the label through the concepts explained above.

Now that the structure of the positioning system has been described, the method that manages the operation thereof is set out below. fhe method includes a series of steps, a preliminary step of which consists of calibrating the space surrounding the system.

To perform this mapping, the chart 8 is fitted into a disc 3. arranged so that the points 80a are facing the exterior of the carousel. As shown in Figure 3. the chart travels - by means of the movement of the carousel - in front of the camera which, by capturing a certain number of images for the same number of positions, captures all the views of the chart inside the arc of the carousel along which the container will subsequently travel.

Based on the field of view that has been created, it is necessary to capture images starting from a starting point inside the field of view up to an end point within the same field. In this preliminary step, within the angular sector of the carousel within which the camera is operating, the chart travels - with the disc stationary - along the entire arc of the carousel corresponding to the camera's arc of view.

The system is designed to capture an image of the chart in each of the predetermined positions where the container will subsequently be photographed during the motion thereof.

Figure 3 shows the sequence of images of the chart that are captured during the movement thereof on the carousel in the field of view.

The purpose of this operation is to calibrate each image captured at a precise position by converting the unit in pixels into a unit in millimetres.

This will mean that identical metric amounts will correspond to different pixel amounts when comparing the same chart. Due to perspective, when the same container is photographed at the first position (photo one. start of the field of view) or at the last position (last photo, field of view) by the same camera with the same resolution, the reference to be positioned (or any other detail) has fewer pixels than when the said container is photographed in a central position and in front of the camera (example photo, position 8 or 9). Basically, since the image is very lateral, distorted and the said container further away from the camera, the symbol is more distorted and has fewer pixels in the more lateral photos, compared the more central ones, even if, in actual fact, the dimensions of the symbol have not changed.

Conversely, in the more central photos, where the image is less distorted by perspective, the symbol will be larger and have more pixels.

Therefore, a correspondence must be established between the same equal metric amounts (which are the real dimensions of the symbol) and the different pixel amounts forming the basis of the image of the container when photographed, using the calibration chart as a means of calibrating the pixel world to the real world. With the system in question, the space within which a container to be labelled will subsequently transit is calibrated.

At this point, as shown in Figure 4, a container mapping step follows in which a container is placed on a stationary disc and then made to travel from the said starting point to the end point, where - in a subsequent rotary step - the disc will perform a rotary motion about its own axis while still within the camera's field of view.

When the container is placed on the disc it is positioned with the reference element facing the camera and above all visible in all the positions in which the said container will be photographed. In the container, a central axis 21 and a virtual axis 22 running through the reference element 20 are identified.

This axis identification step is used to determine the offset angle between axis 21 of the container and the virtual axis 22 of the reference element, which is done to eliminate misalignment of the virtual targets (the axis of the reference element or any other common point chosen by a user wherein the said point must be common to and visible in all views) with respect to the axis of the container, which differs from one image to the next.

The misalignment is due to the rotary motion of the carousel along a circumferential arc corresponding to the field of view, as shown in Figure 4. In more detail, the misalignment is reduced, image after image, as the container moves closer to the centre of the field of view, when it is in front of and perpendicular to the camera, and subsequently gradually increases as the container moves towards the other end of the field of view, in the opposite direction to the first images.

The study of the misalignment between the two axes (central axis 21 and virtual axis 22 of the reference element ) shows the perspective error of the object even when stationary on the disc within the system's field of view. After mapping the space through the chart and determining the common virtual targets of the container in order to offset the perspective, the method envisages a format creation step in which the container is made to travel through the space within the field of view and this time the rotary motion of the disc is added.

In this step, a container is placed on a disc and rotated to capture a series of images (e.g. 18) of the container in a series of positions starting at the beginning of the field of view and finishing at the end thereof and which are the same in which the chart and the container in the absolute position were photographed.

'fhe same series of images can be taken with the disc rotating around its own axis with the result that the container is captured within a series of views dividing the surface thereof into a clearly defined plurality of sectors.

Indeed, the container - when travelling along the pathway thereof within the field of view - performs a 360° revolution and, since such 360° revolution must start at a starting position and end at an ending position, it is necessary to enter - for each position of the container where an image will be captured - a number of degrees, which, when multiplied by the number of images taken, must equal an entire revolution.

At this point there comes the data processing step, in which the management and control means 7 display, to the user, the number of images received from the camera during the rotary motions of the container and. by means of specific algorithms, the position will thereof will be located/shown in a specific image of the reference element.

In this step, with the container rotating on the disc, the reference element is located and following the rotary motion transmitted to the container via the disc, the reference element will be located/shown by the management and control means 7, but only in certain images.

The control algorithms locate/show this reference element by displaying the centre line of the reference element itself with a target symbol. In this way, the management and control means 7 are able to show the user, in the specific image, the positioning axis of the reference element in addition to the central axis of the container and the virtual axis set for the specific image with the previous steps. Thanks to the space mapping carried out previously, this position is converted first into pixels, then into millimetres, and then into degrees with the aim of calculating the angle of reference between the two axes (the axis 21 of the container and the virtual axis 22, or the reference element).

At this point, now that the mapping of the space through calibration with the chart is known, the diameter of the container is known, the actual physical axes of the container whose image is captured are known, and the resulting perspective offset to apply to the common virtual targets is known, the system calculates the angle between the axis running through the reference element located with the container rotating and the central axis and the virtual axis obtained in the step with the container travelling and the disc stationary.

Next, the angle established by the container from the beginning of the rotary motion to the image in which the reference element was identified must be added as a negative to the aforesaid calculated angle.

The entire method according to the present invention requires a very short time. i.e. approximately 5 minutes.

In addition to the explanations so far. during the subsequent production step the system in question allows the management of an online step in which changes may be made to the parameters while the system is operational.

Furthermore, the system also allows an off-line step in which, while the machine is operational, it is possible to modify certain parameters and see the results immediately. Indeed, the system allows the user to process the images acquired, modifying parameters, and then enter the said modifications immediately to change the way in which the system is operating straight away, with the machine running.

If the user wishes to change a parameter, they can do it online and the machine accepts the modification instantly and applies it straight away.

If. however, it is necessary to carry out more invasive action to modify the set of instructions, the user can work off-line with the software, which will then replace the set of instructions in use without having to stop the machine and production.

After this predominantly method-related description, the operation of the system in question is described as follows.

When a container needs to be labelled, a conveyor device is needed, which places the said container on a disc on a rotating carousel. Once the container is on the disc, the latter is moved by the carousel to the positioning device.

At this point, the disc rotates about its own axis, rotating the container and bringing the latter into the correct position to subsequently receive the label correctly. The positioning of the container is achieved due to the fact that, during the rotation of the container, the camera captured a series of images which the management and control means subsequently processed by locating the position of the reference element on the container and sending a command to rotate the disc by a certain angle so as to bring the container into the correct position to go to the labelling station.

The present invention thus achieves the objects set.

Indeed, the container positioning system and method in question calibrates the space within which a container travels and maps the path that the container will take before being labelled. Advantageously, the container positioning system and method is capable of suggesting to the machine the space within which movements should be made with respect to the field of view.

Furthermore, the system and method according to the present invention provides a machine that is very fast in preliminary operations and very compact and offers the possibility of adding other devices in addition to multiple labelling stations.

Another advantage of the container positioning system and method in question emerges from the fact that the hardware necessary is kept to a minimum with the aim of reducing costs and overall dimensions while keeping the time needed to create the container format to a minimum.

In addition, the container positioning system and method allows the same approach and hardware to be used to create a machine outfeed station dedicated to quality control for the labelled containers.

A yet still further advantage of the container positioning system and method is that the said system and method allows time to be saved during the initial parameterisation for each format, thereby allowing the initial procedures of the machine to be automated and hence facilitating use thereof.

A further but not final advantage of the present invention is that the said system proves to be remarkably easy to use and structurally simple, and works well.

Naturally, further modifications or variants may be applied to the present invention while remaining within the scope of the invention that characterises it.