System and method for spatially detecting any foreign object in a product based on the dielectric properties of the product

Abstract

The present invention provides a system (100) for spatially detecting any foreign object in a product (135) based on the dielectric properties of said product (135), said system (100) comprising: conveyor means (150) adapted to convey the product (135) through the scanning area (S) along a transverse direction (L) at a predefined traversal time interval (T) for traversing the scanning area (S); a plurality of antennas (200) arranged across the transverse direction (L), each antenna (210) of the plurality of antennas (200) adapted to operate in the microwave range, each antenna (210) adapted to transmit an electromagnetic scanning signal adapted to propagate within the scanning region (S) and spread within the product (135); a processing means (250) adapted to generate a first set of values ​​indicative of the dielectric properties of the product (135) based on at least one diffused electromagnetic signal received by at least one antenna (210) of the plurality of antennas (200), the processing means (250) being adapted to compare the first set of values ​​with a second set of values ​​indicative of the dielectric properties of the product (135) in the absence of any foreign object; Equipped with each antenna (210) of the plurality of antennas (200) adapted to transmit the electromagnetic scanning signal at least once within the transverse time interval (T) according to a predefined transmission sequence; Regarding the system (100).

Description

[Technical field]

[0001] The present invention relates to a system for spatially detecting any foreign object in a product according to the preamble of claim 1. In particular, a system and a method for spatially detecting any foreign object in a product based on the dielectric properties of the product itself are described herein. For example, such products can be liquid or solid food products, such as tomato sauce, jam, milk, meat, etc., contained in glass or plastic containers, such as jars, bottles, vials, etc. Also, such products can be cosmetic products (such as soap bars) or pharmaceutical products, contained in suitable glass, paper or plastic containers. The present invention can be advantageously used, for example, in factories producing such products, to automatically detect and / or reject any product that contains foreign objects (such as bone chips, glass shards, rubber, stones, plastic or insects, etc.) or is affected by inhomogeneities, for example due to the presence of abundant air in the product itself.

[0002] Non-invasive identification of any foreign object in a packaged product without contacting or altering the product itself would be particularly useful to avoid the risk of injury to consumers, while at the same time protecting the manufacturer against legal costs, the costs incurred in withdrawing entire lots of goods, and the loss of customer goodwill. Nevertheless, foreign objects represent a risk to producers, since the methods currently used have limitations. For example, metal detectors can only detect conductive materials, X-rays cannot detect low-density plastics or small pieces of wood or glass, in addition to being harmful to workers as they are ionizing radiation, and infrared-based techniques suffer from limited penetration and high absorption due to the presence of water in many of the products that need to be analyzed.

[0003] Unlike the most commonly used techniques, the technique of detecting / identifying objects embedded in structures by electromagnetic waves in the microwave range (300 MHz to 300 GHz), also known as microwave imaging (MWI), distinguishes not by density but by the dielectric properties (e.g., dielectric constant) of the materials that make up the product. This technique makes it possible to overcome the limitations of X-ray devices, since it allows the detection of low-density plastics and glass, in conditions where the dielectric contrast with the product's contents is minimal. Measurements performed with contrast values ​​of about 10% prove its effectiveness. Moreover, the final cost of such microwave devices should be lower than that of X-ray systems, taking into account the absence of the need for expensive ad-hoc sources and receivers. In fact, the components necessary to generate and capture microwaves are readily available in the telecommunications technology market.

[0004] The paper entitled "Microwave Imaging Technology for Food Contamination Monitoring" (https: / / webthesis.biblio.polito.it / 7482 / ), published by Alessandro Giordano and his supervisor Professor Francesca Vipiana at the Polytechnic Institute of Turin in the academic year 2017-2018, describes a microwave-based detection and identification system that makes it possible to inspect food products contained in glass jars (specifically orange marmalade and hazelnut cream). This system consists of an array of antennas placed around the products to be inspected. These antennas emit low-power electromagnetic signals at frequencies in the microwave range that are able to diffuse within the products to be examined and provide a map of the dielectric properties of such products. These maps can then be analyzed to identify any foreign bodies in the products.

[0005] The above-mentioned MWI systems are well known in the art and suffer from several drawbacks which are explained below.

[0006] The first drawback relates to the fact that the map of the dielectric properties of the product is two-dimensional, and therefore such systems do not allow for non-invasive inspection of the entire product, i.e., the previously described systems are unable to provide a three-dimensional map of the dielectric properties of the product, resulting in an inefficient non-invasive inspection system.

[0007] Another drawback is that a two-dimensional map of the dielectric properties of a product can only identify the material of the foreign object and locate the foreign object within a two-dimensional cross-section of the product. However, such a two-dimensional map of the dielectric properties of a product cannot determine the size of the foreign object, nor its exact location within the product. As a result, it is not possible to perform an effective subsequent statistical analysis to reduce or eliminate the cause of the foreign object's presence within the products manufactured along the production line.

[0008] A further drawback relates to the fact that the previously described MWI systems cannot be easily installed in industrial production lines.

[0009] It is therefore an object of the present invention to overcome these and other problems suffered by the prior art, in particular by providing a system and method for spatially detecting any foreign object within a product based on the dielectric properties of the product itself, thereby enabling the entire product to be non-invasively inspected by determining a three-dimensional map of the dielectric properties of the product.

[0010] Another object of the present invention is to provide a system and method for spatially detecting any foreign objects within a product based on the dielectric properties of the product itself, thereby enabling an effective recursive statistical analysis to be performed to reduce or completely eliminate the causes of the presence of foreign objects within products manufactured along a production line.

[0011] It is a further object of the present invention to provide a system and method for real-time spatial detection of any foreign objects within a product being manufactured along an industrial production line based on the dielectric properties of the product itself.

[0012] The invention described herein consists of a system and method for spatially detecting any foreign object within a product based on the dielectric properties of the product itself by determining in real time the dielectric contrast between the product contents and any foreign object.

[0013] Further advantageous features of the invention are set out in the appended claims, which form an integral part of this specification. [Brief description of the drawings]

[0014] The invention will now be described in detail through some non-limiting exemplary embodiments thereof, particularly with reference to the accompanying drawings, in which: [Figure 1] 1 illustrates a schematic diagram of an example of a system for spatially detecting any foreign object in a product, according to an embodiment of the present invention; [Diagram 2] 2 shows an example structural diagram of an array of antennas used in the system of FIG. 1; [Diagram 3] 2 shows an exemplary block diagram of the system of FIG. 1. [Figure 4] 2 shows an exemplary flow diagram of a method for spatially detecting any foreign object in a product in association with the system of FIG. 1; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1, a system 100 for spatially detecting any foreign object in one or more products 135, such as vials, flacons, bottles or jars, made of glass, paper, plastic or other suitable material, having a substantially cylindrical or parallelepiped shape, including food, cosmetic, pharmaceutical or chemical products, is shown diagrammatically. Said system 100 comprises, for example, a production unit 160, a first storage unit 171, a second storage unit 172, conveyor means 150, at least one of a plurality of antennas 200 adapted to operate in the microwave range, and a rejection unit 175 for rejecting at least one product 135 containing one or more foreign objects.

[0016] The production unit 160 is adapted to produce at least one product 135, for example a glass jar containing jam. The production unit 160 may comprise actuator means adapted to carry out production processes, for example washing and filling glass containers, to create the product 135. During these production processes, foreign objects, for example glass shards, for example resulting from accidentally broken containers, may dangerously be included in the at least one product 135. The production unit 160 may comprise actuator means for delivering the at least one product 135, which may comprise an electric motor and / or a servomechanism driven by a hydraulic system.

[0017] The first storage unit 171 is adapted to store at least one product 135 that has not yet been inspected according to the invention, i.e. a product 135 that cannot be presumed not to contain at least one foreign object and therefore excluded. The first storage unit 171 and said production unit 160 can be operatively connected such that the at least one product 135 is movable from the production unit 160 to the first storage unit 171. The first storage unit 171 can comprise actuator means for feeding the at least one product 135, which can have a servo mechanism driven by an electric motor and / or a hydraulic system.

[0018] The second storage unit 172 is adapted to store at least one product 135 that has been inspected according to the invention. The second storage unit 172 may comprise actuator means for feeding the at least one product 135 that has been verified to be free of any foreign object, the actuator means may comprise a servo mechanism driven by an electric motor and / or a hydraulic system.

[0019] The conveyor means 150 is adapted to convey said products 135 along a transverse direction L through a scanning area S (visible in FIG. 2) at a predefined transverse time interval T for transversing said scanning area S. For example, the conveyor means 150 may move at least one product 135 to be inspected at a constant speed of about 0.5 m / s by conveying said product 135 from a first storage unit 171 to a second storage unit 172. The conveyor means 150 may be operatively connected to the first storage unit 171 and the second storage unit 172 and may comprise, for example, a belt, a chain, etc., made of, for example, rubber and / or metal. The conveyor means 150 may comprise a servo mechanism driven by an electric motor and / or a hydraulic system.

[0020] A plurality of antennas 200 (described in detail with reference to FIG. 2 ) are arranged across a transverse direction L of a scanning area S. Each antenna 210 of the plurality of antennas 200 is adapted to operate in the microwave range and adapted to transmit an electromagnetic scanning signal adapted to propagate within the scanning area S and spread within said product 135 passing through the scanning area S. In one embodiment of the invention, the antennas 210 of said plurality of antennas 200 may all be identical. The plurality of antennas 200 may, for example, be operatively connected to a conveyor means 150 such that at least one product 135 is inspected and moved from a first storage unit 171 to a second storage unit 172.

[0021] The reject unit 175 is adapted to reject at least one product 135 containing one or more foreign objects during its movement along the conveyor means 150. The reject unit 175 is located downstream of said plurality of antennas 200 and possibly upstream of the second storage unit 172. The reject unit 175 may comprise signaling means (such as, for example, an audible and / or visual signaling device) indicating the detection of at least one foreign object in the product 135, actuator means for conveying at least one product 135 in which the presence of at least one foreign object has been confirmed to a removal zone, not shown in Fig. 1. The actuator means may comprise a servo mechanism driven by an electric motor and / or a hydraulic system.

[0022] However, the system 100 may or may not include a production unit 160, which is the case when the product 135 contained within the first storage unit 171 is manufactured at a different location than the location where the system 100 described herein is being used.

[0023] Fig. 2 shows an example structural diagram of a plurality of antennas 200 (also referred to as an antenna array) used in the system 100 of Fig. 1. Each antenna 210 of the plurality of antennas 200 is adapted to transmit or receive at least one electromagnetic signal in the 300 MHz to 300 GHz electromagnetic spectrum region, i.e., each antenna 210 of the plurality of antennas 200 is adapted to operate in the microwave region.

[0024] The multiple antennas 200 are arranged across the transverse direction L of the scanning area S and have at least three antennas 210 adapted to at least partially surround the product 135, and the at least three antennas 210 are arranged such that the product 135 can be driven and moved along the transverse direction L by the driving means 150 at a speed of, for example, 0.5 m / s.

[0025] In one embodiment of the invention, the antennas 210 of the multiple antennas 200 may be arranged to form an arc or a circumference in a plane transverse to the transverse direction L. In this embodiment of the invention, the scan area S may be defined as a spatial region centered within the arc or circumference formed by the arrangement of the antennas 210, and may have an extension along the transverse direction L equal to a first dimension of the product 135 along the transverse direction L plus a first guard length, the spatial region having an extension along a direction perpendicular to the transverse direction L equal to a second dimension of the product 135 along a direction perpendicular to the transverse direction L plus a second guard length, and the height of the spatial region is subtended by the arc or circumference formed by the arrangement of the antennas 210. For example, assuming that the product 135 has a cylindrical shape with a diameter of 8 cm, both the first and second dimensions of the product 135 will coincide with its diameter, i.e., 8 cm. Both the first and second guard lengths may be defined as two fractions (e.g., 1 / 2 and 1 / 4) of the first and second dimensions of the product 135, respectively. This results in the scanning area S being defined by a 12 cm x 10 cm portion of space subtended in height by the arc or circumference formed by the arrangement of the antennas 210. In other embodiments of the invention, the antennas 210 of the plurality of antennas 200 may be arranged to form a dashed line or a rectangular or trapezoidal perimeter in a plane transverse to the transverse direction L. To this end, in both of these embodiments of the invention, the antennas 210 may be housed in a support structure. Such a structure may be fixed to a lateral support mounted on the conveyor means 150. In both of the previously described embodiments of the invention, the transverse plane may be substantially perpendicular to the transverse direction L.

[0026] In another embodiment of the present invention, the scanning area S may be defined by the overlap of the radiation diagrams of each antenna 210 of the plurality of antennas 200, such that the power emitted by each antenna 210 of the plurality of antennas 200 in the scanning area S exceeds a predefined power value. For example, as shown in Fig. 2, in one embodiment of the present invention, the scanning area S may be defined by the space contained between the antennas 210 of the plurality of antennas 200 and delimited by the dimensions of the antennas 210 themselves, such that the power emitted by each antenna 210 of the plurality of antennas 200 exceeds a predefined power value.

[0027] Each antenna 210 of the plurality of antennas 200 is adapted to operate in the microwave range. Each antenna 210 is adapted to transmit an electromagnetic scanning signal that propagates within the scanning region S and spreads within the product 135 (i.e., the electromagnetic scanning signal spreads within at least a portion of the product 135).

[0028] Specifically, the product 135 is adapted to pass through the scanning area S so as to completely traverse the scanning area S in a predefined traversal time interval T. The traversal time interval T may depend on the speed of movement of the product 135 being conveyed by the conveyor means 150 and on the dimensions of the scanning area S. When the product 135 passes through said scanning area S in the traversal time interval T, each antenna 210 of the plurality of antennas 200 is adapted to transmit an electromagnetic scanning signal at least once according to a predefined transmission sequence. The electromagnetic scanning signals transmitted sequentially by each antenna 210 are diffused within the product 135 (i.e., diffused within at least a portion of the product 135). As a result, at least one diffused electromagnetic signal is received by the remaining antennas 210 that are not transmitting. The set of diffused electromagnetic signals can be used to determine a three-dimensional map of the dielectric properties of the product 135. The frequency and power of the electromagnetic scanning signal depend on the size and dielectric properties of the contents of the product 135 to be analyzed, and the conductivity of the material contained in the product 135 is particularly important to ensure sufficient penetration of the electromagnetic scanning signal into the product 135.

[0029] The sequence of transmissions by the multiple antennas 200 may be defined, for example, as sequential transmissions based on a predefined order of the antennas 210 of the multiple antennas 200. For example, assuming that the antennas 210 are arranged along a line, the transmission sequence may start with a first antenna located at one end of the line and end with a last antenna located at the other end of the line. In other embodiments of the invention, other scanning sequences may be considered based on the geometry of the product 135 and / or the geometry of the scanning area S.

[0030] Fig. 3 shows an exemplary block diagram of the system 100 of Fig. 1. The system 100 may comprise an interface means 220, a communication means 230, a memory means 240, and a processing means 250, which may be operatively interconnected via a communication bus 201.

[0031] The interface means 220 are adapted to manage the plurality of antennas 200. The interface means 220 may comprise, for example, a device adapted to transmit and receive electromagnetic signals in the microwave range and a respective control unit and / or servomechanism driven by an electric motor and adapted to spatially orient the antennas 210 of the plurality of antennas 200 to optimize the transmission and reception of electromagnetic signals in the scanning area S. The interface means 220 may comprise, for example, sensor means such as photocells, RFID sensors and video cameras for detecting the presence of the product 135 at the entrance of the scanning area S.

[0032] As will be described below by way of example with reference to the flow diagram of FIG. 4, the communication means 230 are adapted to output from the system 100 the information obtained by the method of spatially detecting any foreign object in a product 135, which is the subject of the present invention. The communication means 230 may comprise, for example, a communication unit adapted to communicate with a remote management system and / or server. Said communication unit may have, for example, an Ethernet interface, a WiFi interface, a GSM, UMTS, LTE interface, etc. The communication unit may establish a connection with an external device for managing or monitoring the system 100, for example a computer, a smartphone, a tablet, etc. The communication means 230 may allow a user to interact with the system 100. For example, the communication means 230 may comprise output means and input means (respectively, for example a display and an alphanumeric keyboard), or an alphanumeric keyboard and a touchscreen display displaying interaction symbols. In other embodiments of the present invention, the communication means 230 may comprise a communication port for connecting to a terminal external to the system 100, for example an RS232 interface or a USB interface. The external terminal of the system 100 may be, for example, a smartphone controlled by a user or operator.

[0033] The memory means 240 allows to store information to be input to and / or output from the system 100, as well as instructions implementing this embodiment of the invention. The memory means 240 may comprise, for example, a solid-state memory of the Flash type. Such information may include, for example, the operating state of the multiple antennas 200 and / or a set of values ​​and / or parameters useful for implementing the method of spatially detecting any foreign object in the product 135, which is the subject of the present invention, such as the values ​​of some physical quantities (such as, for example, the speed of the product 135 passing through the scanning area S, as well as the frequency and power of the electromagnetic scanning signal). The instructions stored in the memory means 240 are explained in detail below with reference to the flow chart of FIG. 4.

[0034] The processing means 250 makes it possible to process information and instructions stored in the memory means 240 and / or received via said interface means 220 and communication means 230 and may comprise, for example, an ARM processor, an Arduino microcontroller, a processor having an x86 or x64 architecture, etc.

[0035] 4, an exemplary method for spatially detecting any foreign objects within a product 135 will now be described with reference to the system 100 of FIG.

[0036] In step 400, a phase of initializing the system 100 is carried out in order to put the system 100 into operation. During this step, for example, the processing means 250 checks the operational status of the elements of the system 100, such as, for example, the production unit 160, the first storage unit 171, the second storage unit 172, the conveyor means 150, the plurality of antennas 200, the rejection unit 175, the interface means 220, the communication means 230, the memory means 240, etc.

[0037] In step 410, the processing means 250 is configured to perform a conveying step. During this step, the processing means 250 controls the conveyor means 150 to convey the product 135 along the transverse direction L through the scanning area S at a predefined transverse time interval T. The transverse time interval T for transversely passing the scanning area S may depend on the speed of movement of the product 135 and on the dimensions of the scanning area S. The speed of movement of the product 135 may be, for example, a substantially constant speed of about 0.5 m / s. During this step, the processing means 250 may receive information from the sensor means of the interface unit 220 indicating the presence of the product 135 at the entrance of the scanning area S. The processing means 250 may then initialize a timer TM for counting the transverse time interval T required for the product 135 to transverse the scanning area S.

[0038] In step 420, the processing means 250 is configured to perform a scanning phase. During this phase, the processing means 250 controls the interface means 220 to transmit an electromagnetic scanning signal in the microwave range by each antenna 210 of the plurality of antennas 200 (the plurality of antennas 200 being arranged across the transverse direction L). In this way, the electromagnetic scanning signal propagates within the scanning region S and spreads within said product 135 (i.e., the electromagnetic scanning signal spreads within at least a portion of the product 135). During said scanning phase, each antenna 210 of the plurality of antennas 200 transmits an electromagnetic scanning signal at least once within a transverse time interval T according to a predefined transmission sequence.

[0039] For example, when the product 135 is conveyed by the conveyor means 150 and enters the scanning area S, a timer TM is activated for counting a traversal time interval T required for the product 135 to traverse the scanning area S. As the product 135 passes through said scanning area S, each antenna 210 of the plurality of antennas 200 is adapted to transmit an electromagnetic scanning signal at least once according to a predefined transmission sequence. When the timer TM reaches a value of the traversal time interval T determined based on the speed of movement of the product 135 and the dimensions of the scanning area S, such that the entire product 135 can be scanned within the traversal time interval T, the transmission sequence stops.

[0040] The transmission sequence is defined a priori (e.g., based on the geometry of the product 135 and / or the geometry of the scan region S). For example, with reference to Figure 2, assuming the multiple antennas 200 comprises six antennas 210 arranged in order from left to right with respect to the transverse direction L, the transmission sequence during the transverse time interval T required for the product 135 to traverse the scan region S may be (1, 2, 3, 4, 5, 6, 6, 5, 4, 3, 2, 1, 1, 2, 3, 4, 5, 6, 6, 5, 4, 3, 2, 1).

[0041] Each antenna 210 of the multiple antennas 200, numbered "1" through "6", sequentially transmits a scanning signal for a transmission time interval t that is less than the traversal time interval T, and for example, the transmission time interval t for each antenna 210 may be defined to be less than or equal to the traversal time interval T divided by the number of elements in the transmission sequence (24 in this example). The transmission time interval t may be, for example, about 10 ms. The electromagnetic scanning signal sequentially transmitted by each antenna 210 from the first antenna "1" through the last antenna "6" spreads within the product 135 (i.e., spreads within at least a portion of the product 135). As a result, at least one spread electromagnetic signal is received by the remaining antennas 210 that are not transmitting (e.g., "2" through "6" when the first antenna "1" is transmitting). The frequency and power of the electromagnetic scanning signal will depend on the size and dielectric properties of the contents of the product 135 being analyzed, with the conductivity of the materials contained in the product 135 being particularly important to ensure sufficient penetration of the electromagnetic scanning signal within the product 135. In other embodiments of the invention, other scanning sequences may be considered, such as, for example, (1,2,3,4,5,6,1,2,3,4,5,6,1,2,3,4,5,6,1,2,3,4,5,6) and (6,5,4,2,1,6,5,4,2,1,6,5,4,2,1,6,5,4,2,1,6,5,4,2,1).

[0042] In step 430, the processing means 250 is configured to perform an analysis step during which the processing means 250 generates a first set of values ​​indicative of the dielectric properties of the product 135 based on at least one diffused electromagnetic signal received by at least one antenna 210 of the plurality of antennas 200. During this step, the processing means 250 compares said first set of values ​​with a second set of values ​​indicative of the dielectric properties of said product 135 in the absence of any foreign object.

[0043] For example, assuming the multiple antennas 200 comprises N antennas 210, the first set of values ​​can be determined using each electromagnetic signal spread by the scanned product 135, each spread electromagnetic signal being received by each antenna 210 of the multiple antennas 200. The first set of values ​​can be determined using the N values ​​expressed as both the phase and the amplitude of such received electromagnetic signals (e.g., using complex numbers) for all possible pairs of antennas 210, excluding the self-interaction term, which is the case when the transmitting and receiving antennas are coincident. 2 A first interaction matrix including -N interactions can be determined. The first interaction matrix represents a first set of values ​​indicative of the dielectric properties of the product 135. Similarly, a second set of values ​​can be determined using electromagnetic signals spread by the product 135 in the absence of any foreign object, the spread electromagnetic signals being received by each antenna 210 of the multiple antennas 200. The first interaction matrix represents a first set of values ​​indicative of the dielectric properties of the product 135. The ... second set of values ​​can be determined using the -N interactions, expressed as both the phase and the amplitude of the received electromagnetic signals (e.g., using complex numbers) of all possible pairs of antennas 210, excluding the self-interaction term. 2 It is possible to determine a second interaction matrix comprising -N interactions. The second interaction matrix represents a second set of values ​​indicative of the dielectric properties of said product 135 in the absence of any foreign object. The second set of values ​​may be predetermined during an initialization phase described in step 400 and stored in memory means by said processing means 250. Similarly, the first set of values ​​may be stored in memory means 240 by said processing means 250 during an analysis phase described herein.

[0044] The processing means 250 compares the first and second set of values, for example by the difference between the first and second interaction matrices, thereby obtaining a differential interaction matrix indicative of dielectric properties of one or more foreign objects that may be present in the scanned product. Similarly, the differential interaction matrix may also be stored in the memory means 240 by said processing means 250.

[0045] The processing means 250 are capable of decomposing the differential interaction matrix into eigenvectors using an algorithm based on truncated singular value decomposition known from the literature mentioned above. This transformation makes it possible to filter useful information and to cancel noise components that are discernible through the application of said algorithm. Using the Born approximation, it is possible to consider the incident electromagnetic scanning signal and the total electromagnetic field in the scanning area S as being approximately equal, and on this basis it is possible to assume that the measured electromagnetic field variations, i.e. the differential interaction matrix, are linearly dependent on the variations of the dielectric properties in the volume of the product 135, which may be caused by the presence of at least one foreign object. This makes it possible to determine from the differential interaction matrix a three-dimensional map of the dielectric properties of the volume of the product 135 under examination, thus building up a three-dimensional tomography of the scanned product 135.

[0046] In step 440, the processing means 250 checks whether the product 135 contains at least one foreign object therein. For this purpose, for example, the processing means 250 may check that all of the values ​​of the differential interaction matrix are not zero. If so, the processing means 250 will execute step 450, otherwise it will execute step 460.

[0047] In step 450, the processing means 250 outputs signaling information via said communication means 230. For example, the signaling information may be displayed on a screen, allowing an operator to monitor in real time the presence of one or more foreign objects in one or more products 135. Such signaling information may activate actuator means of the rejection unit 175 to reject those products 135 containing at least one foreign object. For example, the products 135 may be rejected using a pneumatic cylinder that drops the rejected products 135 into a collection compartment. Such signaling information may be sent to the management system of the system 100 (which may be remote) via a communication interface, for example Wi-Fi, GSM, Ethernet, etc. The processing means 250 may store the values ​​of the differential interaction matrix in the memory means 240 to collect information about the size, location and type of foreign objects detected in one or more products 135. This is useful for analyzing the cause of the presence of one or more foreign objects in one or more products 135. The processing means 250 then executes step 460 .

[0048] In step 460, the processing means 250 checks whether there are other products 135 that need to be scanned, for example using sensors such as video cameras, photocells, etc. If there are, the processing means will execute step 410, otherwise it will execute step 470.

[0049] In step 470, the processing means 250 performs all operations necessary to complete the operation of the system 100. During this step, the processing means 250 may indicate the inoperable state of the system 100, for example, by using a visual indication (e.g., an LED indicator light) and / or an audible indication (e.g., a buzzer or loudspeaker).

[0050] The advantages of the present invention are apparent from the above description.

[0051] The system and method for spatially detecting any foreign object in a product, which is the subject of the present invention, advantageously enables non-invasive inspection of the entire product and determining a three-dimensional map of the dielectric properties of such a product.

[0052] Another advantage of the present invention is that any foreign object in a product is detected based on the dielectric properties of the product itself, making it possible to collect information such as size, location and type of foreign object contained in the product, thereby allowing for effective analysis to reduce or completely eliminate the cause of the presence of any foreign object in the products manufactured along the production line.

[0053] A further advantage of the present invention is that it provides a system and method that allows for real-time spatial detection of any foreign object within a product based on the dielectric properties of the product itself by appropriately configuring certain of a plurality of antennas and the sequence of transmission of the antennas' electromagnetic scanning signals.

[0054] Naturally, without prejudice to the principles of the invention, the form and implementation details of the embodiments may vary widely from those described and illustrated herein, solely by way of non-limiting example, but without departing from the scope of protection of the invention as set forth in the appended claims.

Claims

1. 1. A system for spatially detecting any foreign object in a product based on a dielectric property of said product, said system comprising: conveyor means adapted to convey said product along a transverse direction through said scanning area at a predefined traverse time interval for traversing said scanning area; a plurality of antennas disposed across the transverse direction, the plurality of antennas comprising N antennas, each antenna of the plurality of antennas adapted to operate in a microwave region, each antenna adapted to transmit an electromagnetic scanning signal adapted to propagate within the scanning region and spread within the product; processing means adapted to generate a first set of values ​​indicative of the dielectric properties of the product based on at least one diffused electromagnetic signal received by at least one of the plurality of antennas, the processing means being adapted to compare the first set of values ​​with a second set of values ​​indicative of the dielectric properties of the product in the absence of any foreign object; Equipped with each antenna of the plurality of antennas adapted to transmit the electromagnetic scanning signal at least once within the transverse time interval according to a predefined transmit sequence; the first set of values ​​is determined by the electromagnetic signals spread by the scanned product, each electromagnetic signal being received by each antenna of the plurality of antennas excluding a self-interaction term where a transmitting antenna and a receiving antenna coincide, determining a first interaction matrix including N 2 -N first interaction values ​​expressed as both phase and amplitude of the at least one spread electromagnetic signal from among all possible antenna pairs; the second set of values ​​is determined by a prior electromagnetic signal spread by the scanned product in the absence of any foreign object, each electromagnetic signal being received by each antenna of the plurality of antennas excluding the self-interaction term where the transmitting antenna and the receiving antenna coincide, and determining a second interaction matrix including N 2 −N second interaction values ​​expressed as both the phase and the amplitude of the at least one spread electromagnetic signal from among all possible antenna pairs; the processing means is adapted to compare the first and second set of values ​​by a difference between the first and second interaction matrices, thereby obtaining a differential interaction matrix indicative of the dielectric properties of one or more foreign objects that may be present in the scanned product. system.

2. The system of claim 1 , wherein the plurality of antennas comprises at least three antennas adapted to at least partially surround the product.

3. The system of claim 1 or 2, wherein the antennas of the plurality of antennas are arranged to form an arc or a circumference in a plane transverse to the transverse direction.

4. 4. The system of claim 3, wherein the scan area is defined as a spatial area centered within the arc or circumference formed by the placement of the antennas, having an extension along the transverse direction equal to a first dimension of the product along the transverse direction plus a first guard length, the spatial area having an extension along the direction perpendicular to the transverse direction equal to a second dimension of the product along a direction perpendicular to the transverse direction plus a second guard length, and a height of the spatial area is subtended by the arc or circumference formed by the placement of the antennas.

5. 5. The system of claim 1, wherein the frequency and power of the electromagnetic scanning signal are dependent on the size, dielectric properties and electrical conductivity of the product contents.

6. 6. The system according to claim 1 , wherein the transmission sequence of the plurality of antennas is defined as sequential transmission according to a predefined order of the antennas of the plurality of antennas.

7. 7. The system of claim 1, wherein the traverse time interval is determined based on a speed of movement of the product and a dimension of the scanning area such that the entire product can be scanned within the traverse time interval.

8. 8. The system of claim 1 , wherein each antenna of the plurality of antennas is adapted to transmit or receive at least one electromagnetic signal in the electromagnetic spectrum band comprised between 300 MHz and 300 GHz.

9. 7. A system according to any one or more of the preceding claims, comprising memory means adapted to store said first set of values ​​and / or said second set of values.

10. 1. A method for spatially detecting any foreign object in a product based on a dielectric property of said product, said method comprising: a conveying step in which a conveyor means conveys the product along a transverse direction through the scanning area at a predefined transverse time interval for traversing the scanning area; a scanning step in which an electromagnetic scanning signal in the microwave range is transmitted by each antenna of a plurality of antennas disposed across the transverse direction, the plurality of antennas having N antennas, the electromagnetic scanning signal propagating within the scanning region and dispersing within the product; an analyzing step in which a processing means generates a first set of values ​​indicative of the dielectric properties of the product based on at least one diffused electromagnetic signal received by at least one of the plurality of antennas, and the processing means compares the first set of values ​​to a second set of values ​​indicative of the dielectric properties of the product in the absence of any foreign object; Equipped with during said scanning step, each antenna of said plurality of antennas transmits said electromagnetic scanning signal at least once within said transverse time interval according to a predefined transmission sequence; During the analysis step, the first set of values ​​is determined by the electromagnetic signals spread by the scanned product, each electromagnetic signal being received by each antenna of the plurality of antennas excluding a self-interaction term, which is the case when a transmitting antenna and a receiving antenna coincide, and determining a first interaction matrix including N 2 -N first interaction values ​​expressed as both phase and amplitude of the at least one spread electromagnetic signal among all possible antenna pairs; the second set of values ​​is determined by the electromagnetic signals spread by the scanned product in the absence of any foreign object, each electromagnetic signal being received by each antenna of the plurality of antennas excluding the self-interaction term where the transmitting antenna and the receiving antenna coincide, and determining a second interaction matrix including N 2 −N second interaction values ​​expressed as both the phase and the amplitude of the at least one spread electromagnetic signal from among all possible antenna pairs; the processing means is adapted to compare the first and second set of values ​​by a difference between the first and second interaction matrices, thereby obtaining a differential interaction matrix indicative of the dielectric properties of one or more foreign objects that may be present in the scanned product. method.

11. The method of claim 10 , wherein the plurality of antennas comprises at least three antennas adapted to at least partially surround the product.

12. 12. The method of claim 10 or 11, wherein the antennas of the plurality of antennas are arranged to form an arc or a circumference in a plane transverse to the transverse direction.

13. 13. The method of claim 12, wherein the scan area is defined as a spatial area centered within the arc or circumference formed by the placement of the antennas, having an extension along the transverse direction equal to a first dimension of the product along the transverse direction plus a first guard length, the spatial area having an extension along the direction perpendicular to the transverse direction equal to a second dimension of the product along a direction perpendicular to the transverse direction plus a second guard length, and a height of the spatial area is subtended by the arc or circumference formed by the placement of the antennas.

14. 14. A method according to any one or more of claims 10 to 13, wherein the frequency and power of the electromagnetic scanning signal are dictated by the size, dielectric properties and electrical conductivity of the product contents.

15. 15. The method according to any one or more of claims 10 to 14, wherein the transmission sequence of the plurality of antennas is defined as sequential transmission according to a predefined order of the antennas of the plurality of antennas.

16. 16. A method according to any one or more of claims 10 to 15, wherein the traverse time interval is defined based on a speed of movement of the product and a dimension of the scanning area such that the entire product can be scanned within the traverse time interval.

17. 17. The method according to any one or more of claims 10 to 16, wherein each antenna of the plurality of antennas is adapted to transmit or receive at least one electromagnetic signal in the electromagnetic spectrum band comprised between 300 MHz and 300 GHz.

18. 18. A method according to any one or more of claims 10 to 17, comprising a storing step in which the processing means stores the first set of values ​​and / or the second set of values ​​in a memory means.

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