Wrapping machine equipped with a rotating radio-identification system to read RFID tags on loads to be wrapped
The wrapping machine with a rotating radio-identification system addresses the challenge of reading RFID tags on loads during wrapping by using dual RFID readers to automate and enhance the accuracy of RFID tag inventory, improving logistics efficiency.
Patent Information
- Application Number
- FR2022008546
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-08-26
- Publication Date
- 2025-06-06
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing wrapping machines struggle to efficiently and reliably read RFID tags on loads during the wrapping process, leading to increased processing time and potential human errors in logistics and transport sectors.
A wrapping machine equipped with a rotating radio-identification system that includes two RFID readers with distinct antennas positioned to interrogate and receive identification signals from RFID tags on loads, allowing for automated and reliable reading of RFID tags during the wrapping operation.
The system enables efficient and accurate inventory of RFID tags on loads, distinguishing between central and external tags, thereby reducing processing time and minimizing human error in logistics operations.
Smart Images
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Abstract
Description
Title of the invention: Wrapping machine equipped with a rotating radio-identification system for reading RFID tags on loads to be wrapped Technical field
[0001] The invention relates to a wrapping machine for wrapping loads on a pallet.
[0002] It relates more particularly to a wrapping machine comprising a chassis, at least one arm mounted so as to be able to rotate on the chassis around a central axis, and a carriage mounted so as to be able to move in translation on the arm and supporting a device for unwinding a wrapping film.
[0003] The invention finds an application in the field of wrapping loads placed on pallets, by means of a wrapping film, for example of the stretch film type, for the purposes of handling and securing loads in the industrial, mass distribution, logistics and transport sectors. Prior art
[0004] As is known, in the logistics and transport sector, the loads to be transported and delivered regularly carry RFID tags, so that an operator can scan and inventory the RFID tags, and therefore the loads, individually by means of a radio-identification reader which interrogates and receives the identification signals coming from these RFID tags, associated with respective tag identifiers.
[0005] Conventionally, the radio-identification reader transmits energy to the RFID tag via radio waves, as well as a request for information to the RFID tag located in its electromagnetic field, and it receives the response from the RFID tag, which contains its tag identifier, for retransmission to a relevant processing unit; communication between the radio-identification reader and the RFID tag being possible thanks to each RFID antenna integrated in each of these two components.
[0006] Thus, it is possible to inventory the loads on the pallet and therefore ensure improved monitoring, management and traceability of the loads in the logistics circuit. However, this operation of interrogating / reading the RFID tags is generally carried out at the time of placing the loads on the pallet or during an additional step in a radio identification tunnel (or RFID tunnel), before wrapping, which increases the processing and management time of these loads in the logistics process, not to mention the problems of human error during querying / reading, especially if one or more charges are omitted. Summary of the invention
[0007] There is a need to facilitate and improve the reading of RFID tags carried by loads, and in particular loads stacked on a pallet.
[0008] One aim of the invention is to address this problem by providing a solution that makes it possible to interrogate / read RFID tags placed on loads placed on a pallet, in an automated and reliable manner.
[0009] Another aim of the invention is to enable the RFID tags of the loads placed on the pallet to be distinguished from other RFID tags which might be in a nearby environment, and which would therefore be detectable; which is the case in a logistics warehouse where hundreds, or even thousands, of loads (and therefore RFID tags) are distributed in a small space.
[0010] To this end, the invention proposes a wrapping machine for wrapping loads on a pallet, comprising a chassis, at least one arm mounted so as to be able to rotate on the chassis around a central axis, a carriage mounted so as to be able to move in translation on the arm and supporting a device for unwinding a wrapping film, such that said carriage can be moved both in rotation and in translation around a central zone centered on the central axis.
[0011] This wrapping machine is equipped with a radio-identification system designed to interrogate and receive identification signals from detectable RFID tags, associated with respective tag identifiers, over several revolutions of the carriage during a conventional wrapping operation.
[0012] In other words, the radio-identification system is mounted on the wrapping machine, so as to be able to interrogate / read the RFID tags which would be carried by the loads placed on the pallet (hereinafter called central tags), in an automated manner.
[0013] This radio-identification system comprises:
[0014] - at least one first radio-identification reader mounted on the trolley and provided of a first receiving antenna facing towards the central zone in order to interrogate and receive on the several revolutions of the carriage first identification signals among the identification signals;
[0015] - at least one second radio-identification reader mounted on the trolley and provided of a second receiving antenna facing in a direction opposite to the central zone, towards the outside of the central zone, in order to receive on the several revolutions of the carriage second identification signals among the identification signals.
[0016] Thus, the first radio identification reader and the second radio identification reader are mounted on the carriage, so that these two readers are moved in rotation and vertical translation with the carriage around the pallet, and therefore around the loads carrying their RFID tags, during a winding operation of these loads. The RFID tags carried by the loads are therefore fixed, while the readers and their antennas are mobile. The invention therefore takes advantage of this wrapping machine and its carriage to interrogate / read the RFID tags carried by the loads all around the pallet and over the entire height of the loads.
[0017] To clearly distinguish the RFID tags carried by the loads from other nearby RFID tags, the first receiving antenna is turned towards the central zone, and therefore towards the loads and their RFID tags, while the second receiving antenna is turned in a direction opposite to the central zone, and therefore in a direction opposite to the loads.
[0018] The radio-identification system also comprises a processing module connected to the first radio-identification reader and to the second radio-identification reader to receive the first identification signals and the second identification signals, where this processing module is configured to inventory each RFID tag, among the detectable RFID tags, by analyzing and comparing the first identification signals and the second identification signals which are associated with the tag identifier of said RFID tag in order to classify said RFID tag as being a central tag located in the central zone by being fixed on a load to be wrapped or as being an external tag located outside the central zone.
[0019] Thus, by analyzing and comparing the first identification signals and the second identification signals of an RFID tag, the processing module determines whether this RFID tag is located in the central zone (and is therefore an RFID tag carried by one of the loads being wrapped by the wrapping machine) or whether this RFID tag is located outside the central zone (and therefore an RFID tag which is not carried by one of the loads being wrapped).Indeed, to the extent that the first receiving antenna and the second receiving antenna are not directed in the same directions, the same RFID tag will give rise to first identification signals (coming from the first receiving antenna) and to second identification signals (coming from the second receiving antenna) which will necessarily have distinct characteristics; and thus an analysis and a comparison of these first identification signals and of these second identification signals allows this classification between central tag and external tag.
[0020] For the inventory of loads being wrapped, the processing module will thus be able to retain only the RFID labels which are classified as central labels.
[0021] According to one characteristic, the processing module is configured to: - establish first reception powers for the first respective identification signals received on the several turns of the trolley; and - establish second reception powers for the respective second identification signals received on the several revolutions of the trolley; and this processing module is configured to inventory each RFID tag by analyzing and comparing the first receive powers and the second receive powers established for the respective first identification signals and second identification signals which are associated with the tag identifier of said RFID tag.
[0022] Thus, the processing module studies the powers on reception of the first and second identification signals, in order to be able to distinguish between central label and external label.
[0023] According to one possibility, the processing module is configured to inventory each RFID tag by: - calculating a first reference reception power which is a function of the first reception powers of the first identification signals which are associated with the tag identifier of the RFID tag; - calculating a second reference reception power which is a function of the second reception powers of the second identification signals which are associated with the tag identifier of the RFID tag; - classifying the RFID tag as a core tag if the first reference reception power is greater than the second reference reception power, and - classifying the RFID tag as an external tag if the first reference reception power is lower than the second reference reception power.
[0024] According to another possibility, the first reference reception power corresponds to a maximum of the first reception powers of the first identification signals which are associated with the tag identifier of the RFID tag, and the second reference reception power corresponds to a maximum of the second reception powers of the second identification signals which are associated with the tag identifier of the RFID tag.
[0025] According to another possibility, for each RFID tag, among the detectable RFID tags, the processing module is configured to: - calculating a first distance between the RFID tag and the first receiving antenna based on the first reception powers of the first identification signals which are associated with the tag identifier of the RFID tag, - calculate a second distance between the RFID tag and the second antenna of receiving as a function of the second powers in reception of the second identification signals which are associated with the tag identifier of the RFID tag; and - classifying the RFID tag as a central tag or as an external tag also as a function of the first distance and the second distance.
[0026] Thus, the classification can also be established according to the distances between RFID tag and reception antenna, established on the basis of reception powers.
[0027] In a particular embodiment, an inertial unit mounted on the carriage to estimate in real time at least a position, an orientation and a speed of the carriage in the space around the central zone, where the processing module is connected to the inertial unit in order to receive the position, the orientation and the speed of the carriage and synchronize them with the receptions of the first identification signals coming from the first reception antenna and the second identification signals coming from the second reception antenna, and for each RFID tag, among the detectable RFID tags, the processing module is configured to establish a location of the RFID tag as a function of the first distance, the second distance and the position, orientation and speed of the carriage, in order to classify the RFID tag as a central tag or as an external tag also as a function of its location.
[0028] In other words, from the speed, the orientation, and the position of the carriage (and therefore the antennas which are carried by this carriage), as well as the angles and the reading properties of each antenna, their distance for each RFID tag, the locations of the detectable RFID tags are geolocated in a reference frame defined at the start of the reading and the rotation of the carriage and therefore of the antennas, thus making it possible to carry out a mapping of the detectable RFID tags.
[0029] Advantageously, the first radio-identification reader and the second radio-identification reader are configured to interrogate and receive the respective first identification signals and second identification signals alternately.
[0030] In a particular embodiment, a support is fixed on the carriage and has an internal face facing the central zone, and an external face, opposite the internal face, and the first reception antenna is turned in the direction of the central zone while being fixed on said internal face of the support, and the second reception antenna is turned in a direction opposite to the central zone while being fixed on said external face of the support.
[0031] According to one possibility, the at least one first radio-identification reader comprises several first radio-identification readers.
[0032] According to a variant, a camera is mounted on the trolley to film and identify in real time loads among the loads present on the pallet, to improve the lo calibration of loads in space, and in particular for the detection of objects, the identification of shapes, the reading of 1D / 2D bar codes to possibly associate with loads or packages.
[0033] According to another variant, a laser or lidar remote sensing system is mounted on the trolley to establish distances between the trolley and loads among the loads present on the pallet, also to improve the location of the loads in space as well as their representation.
[0034] The invention also relates to a wrapping method implementing wrapping of loads on a pallet by means of a wrapping machine according to the invention, and during which the radio-identification system interrogates and receives identification signals from detectable RFID tags, associated with respective tag identifiers, over several revolutions of the carriage during a wrapping operation, with the following steps:
[0035] - interrogation and reception on the several turns of the trolley of first signals identification among the identification signals, by the first receiving antenna of the at least one first radio-identification reader;
[0036] - interrogation and reception on the several turns of the carriage of second signals identification among the identification signals, by the second receiving antenna of the at least one second radio-identification reader;
[0037] - reception by the processing module of the first identification signals and of the second identification signals;
[0038] - inventory of each RFID tag, among the detectable RFID tags, in analyzing and comparing the first identification signals and the second identification signals which are associated with the tag identifier of said RFID tag in order to classify said RFID tag as being a central tag located in the central area by being attached to a load to be wrapped or as being an external tag located outside the central area. Brief description of the drawings
[0039] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of a non-limiting example of implementation, made with reference to the appended figures in which:
[0040] [Fig.l] is a perspective view of a wrapping machine according to the invention, where the support mounted on the carriage is visible, the radio-identification readers not being illustrated;
[0041] [Fig.2] is a perspective and partial view of the wrapping machine of [Fig.l], zoomed in on the support from the side of its internal face receiving three first radio-identification readers;
[0042] [Fig.3] is a perspective and partial view of the wrapping machine of [Fig. 1], zoomed in on the support from the side of its external face receiving a second radio-identification reader;
[0043] [Fig.4] is a schematic side view of the wrapping machine of [Fig.l];
[0044] [Fig.5] is a schematic top view of the wrapping machine of [Fig.l];
[0045] [Fig.6] is a schematic side and partial view of the wrapping machine of [Fig.l].
[0046] [Detailed description of one or more embodiments of the invention]
[0047] With reference to [Fig.l], a wrapping machine 1, according to an exemplary embodiment of the invention, for wrapping loads 81 on a pallet 80, comprises a frame 10, at least one arm 11 mounted to move in rotation on the frame 10 around a central axis 12, and a carriage 13 mounted to move in translation on the arm 11 parallel to the central axis 12; this central axis 12 being of vertical or orthogonal extension to the horizontal plane on which the frame 10 of the wrapping machine 1 rests. Thus, the arm 11 rotates around the central axis 12 and therefore around the pallet 80 and its loads 81; and the carriage 13 slides vertically along the arm 11.
[0048] The wrapping machine 1 comprises a device for unwinding a wrapping film 14 mounted on the carriage 13, so that the carriage 13 and this device for unwinding the wrapping film 14 are movable both in rotation and in translation around a central zone 71 centered on the central axis 12; the pallet 80 being placed in this central zone 71, so that the device for unwinding the wrapping film 14 rotates around the pallet 80 and its loads 81 to wrap these loads 81 from top to bottom (or from bottom to top) and all around the pallet 80, preferably over several turns.
[0049] According to the invention, the wrapping machine 1 is equipped with a radio-identification system 2 designed to interrogate and receive identification signals from detectable RFID tags 91, 92, associated with respective tag identifiers, over several revolutions of the carriage 13 during a wrapping operation.
[0050] This radio-identification system 2 comprises a support 20 which is fixed on the carriage 13 and which has an internal face 21 facing the central zone 71, and an external face 22, opposite the internal face 21, and which is therefore facing an external zone 72 which is a peripheral zone extending around the central zone 71 and therefore the pallet 80.
[0051] This radio-identification system 2 comprises at least a first radio-identification reader 3 mounted on the carriage 13, and more specifically on the internal face 21 of the support 20, where this first radio-identification reader 3 is provided with a first reception antenna facing towards the central zone 71 in order to interrogate and receive on the several turns of the carriage 13 first identification signals among the identification signals. In the example illustrated in [Fig.2], the system Radio-identification 2 includes three first Radio-identification 3 readers.
[0052] This radio-identification system 2 further comprises at least one second radio-identification reader 4 mounted on the carriage 13, and more specifically on the external face 22 of the support 20, where this second radio-identification reader 4 is provided with a second reception antenna facing in a direction opposite to the central zone 71, towards the outside of the central zone 71 (in other words facing towards the external zone 72), in order to receive on the several turns of the carriage 13 second identification signals among the identification signals. In the example illustrated in [Fig.5], the radio-identification system 2 comprises a single second radio-identification reader 4.
[0053] For the remainder of the description, it is understood that the detectable RFID tags 91, 92 belong to one or other of the following two tag categories: - a central label 91 located in the central zone 71 and being fixed on a load 81 to be wrapped placed on the pallet 80; and - external label 92 located outside the central zone 71, in other words located in the external zone 72.
[0054] Thus, the or each first radio-identification reader 3 interrogates and receives first identification signals from the central tags 91, and possibly also from one or more external tags 92. The or each second radio-identification reader 4 interrogates and receives second identification signals from one or more external tags 92, and possibly also from one or more central tags 91.
[0055] Thus, the same RFID tag, whether it is a central tag 91 or an external tag 92, can be detected both by the first radio-identification reader 3 (or one of the first radio-identification readers 3) and by the second radio-identification reader 4 (or one of the second radio-identification readers 4). The same RFID tag will therefore give rise to first identification signals (containing its tag identifier) and to second identification signals (also containing its tag identifier) on the several revolutions of the carriage 13.
[0056] The radio-identification system 2 comprises a processing module 5 connected to the first radio-identification reader(s) and to the second radio-identification reader(s) to receive the first identification signals and the second identification signals. This processing module 5 is for example an electronic card, a processor, a set of electronic cards and / or processors.
[0057] According to one possibility, the first radio identification reader 3 and the second radio identification reader 4 are configured to interrogate and receive the respective first identification signals and second identification signals alternately.
[0058] This processing module 5 is configured to inventory each RFID tag, among the detectable RFID tags 91, 92, by analyzing and comparing the first identification signals and the second identification signals which are associated with the tag identifier of said RFID tag in order to classify said RFID tag as being a central tag 91 or as being an external tag 92.
[0059] To do this, the processing module 5 is designed to: - establishing first reception powers for the first respective identification signals received on the several revolutions of the carriage 13; and - establishing second reception powers for the respective second identification signals received on the several revolutions of the carriage 13; and the processing module 5 is configured to inventory each RFID tag by analyzing and comparing the first receive powers and the second receive powers established for the respective first identification signals and second identification signals which are associated with the tag identifier of said RFID tag.
[0060] In principle, for a central tag 91, the first reception powers will be greater than the second reception powers, because the or each first radio-identification reader 3 is turned towards this central tag 91 while the or each second radio-identification reader 4 is turned in a direction opposite to this central tag 91. On the other hand, for an external tag 92, the second reception powers will be greater than the first reception powers, because the or each second radio-identification reader 4 is turned towards this external tag 92 while the or each first radio-identification reader 3 is turned in a direction opposite to this external tag 92.
[0061] As an example, the processing module 5 is configured to inventory each RFID tag by: - calculating a first reference reception power which is a function of the first reception powers of the first identification signals which are associated with the tag identifier of the RFID tag; - calculating a second reference reception power which is a function of the second reception powers of the second identification signals which are associated with the tag identifier of the RFID tag; - classifying the RFID tag as a core tag 91 if the first reference reception power is greater than the second reference reception power, and - classifying the RFID tag as an external tag 92 if the first reference reception power is lower than the second reference reception power.
[0062] The first reference receive power may correspond to a maximum (or an average) of the first receive powers of the first identification signals that are associated with the tag identifier of the RFID tag, and the second reference receive power corresponds to a maximum (or an average) of the second receive powers of the second identification signals that are associated with the tag identifier of the RFID tag.
[0063] According to one possibility, the processing module 5 is configured to: - calculating a first distance between the RFID tag and the first receiving antenna 3 as a function of the first reception powers of the first identification signals which are associated with the tag identifier of the RFID tag, - calculating a second distance between the RFID tag and the second receiving antenna 4 as a function of the second reception powers of the second identification signals which are associated with the tag identifier of the RFID tag; and - classify the RFID tag as a central tag 91 or as an external tag 92 also depending on the first distance and the second distance.
[0064] Optionally and in addition to the radio-identification system 2, it is possible to provide an inertial unit 6 mounted on the carriage 13, and for example on the support 20, to estimate in real time at least one position, one orientation and one speed of the carriage 13 in the space around the central zone 71.
[0065] The processing module 5 is then connected to this inertial unit in order to receive the position, orientation and speed of the carriage 13 in real time and synchronize them with the receptions of the first identification signals coming from the (or each) first reception antenna 4 and the second identification signals coming from the (or each) second reception antenna 4.
[0066] Thus, for each RFID tag, among the detectable RFID tags 91, 92, the processing module 5 will be configured to establish a location of the RFID tag as a function of the first distance, the second distance and the position, orientation and speed of the carriage 13, in order to classify the RFID tag as a central tag 91 or as an external tag 92 also as a function of its location.
[0067] According to one possibility, the data processed by the processing module 5, and in particular the inventory data relating to the classification of the labels, can be communicated to a remote server or a central unit, for example by wired or wireless means.
Claims
Claims
1. Wrapping machine (1) for wrapping loads (81) on a pallet (80), comprising a frame (10), at least one arm (11) mounted rotatably on the frame (10) about a central axis (12), a carriage (13) mounted translatably on the arm (11) and supporting a device for unwinding a wrapping film (14), so that said carriage (13) is movable both in rotation and in translation about a central zone (71) centered on the central axis (12), said wrapping machine (1) being characterized in that it is equipped with a radio-identification system (2) configured to interrogate and receive identification signals from detectable RFID tags (91, 92), associated with respective tag identifiers, over several revolutions of the carriage (13) during a wrapping operation, said radio-identification system (2) comprising: - at least one first radio-identification reader (3) mounted on the carriage (13) and provided with a first reception antenna facing the central zone (71) in order to interrogate and receive on the several revolutions of the carriage (13) first identification signals among the identification signals; - at least one second radio-identification reader (4) mounted on the carriage (13) and provided with a second reception antenna facing in a direction opposite to the central zone (71), towards the outside of the central zone (71), in order to receive on the several revolutions of the carriage (13) second identification signals among the identification signals; and - a processing module (5) connected to the first radio-identification reader (3) and to the second radio-identification reader (4) for receiving the first identification signals and the second identification signals, wherein said processing module (5) is configured to inventory each RFID tag, among the detectable RFID tags (91, 92), by analyzing and comparing the first identification signals and the second identification signals which are associated with the tag identifier of said RFID tag in order to classify said RFID tag as being a central tag (91) located in the central area (71) by being fixed on a load (81) to be wrapped or as being an external tag (92) located outside the central area (71).
2. Wrapping machine (1) according to claim 1, wherein the processing module (5) is configured to: - establish first reception powers for the respective first identification signals received on the several revolutions of the carriage (13); and - establish second reception powers for the respective second identification signals received on the several revolutions of the carriage (13); and said processing module (5) is configured to inventory each RFID tag by analyzing and comparing the first reception powers and the second reception powers established for the respective first identification signals and the second identification signals which are associated with the tag identifier of said RFID tag.
3. A wrapping machine (1) according to claim 2, wherein the processing module (5) is configured to inventory each RFID tag by: - calculating a first reference reception power which is a function of the first reception powers of the first identification signals which are associated with the tag identifier of the RFID tag; - calculating a second reference reception power which is a function of the second reception powers of the second identification signals which are associated with the tag identifier of the RFID tag; - classifying the RFID tag as a central tag (91) if the first reference reception power is greater than the second reference reception power, and - classifying the RFID tag as an external tag (92) if the first reference reception power is less than the second reference reception power.
4. A wrapping machine (1) according to claim 3, wherein the first reference reception power corresponds to a maximum of the first reception powers of the first identification signals which are associated with the tag identifier of the RFID tag, and the second reference reception power corresponds to a maximum of the second reception powers of the second identification signals which are associated with the tag identifier of the RFID tag.
5. Wrapping machine (1) according to any one of claims 2 to 4, wherein for each RFID tag, among the detectable RFID tags (91, 92), the processing module (5) is configured to: - calculate a first distance between the RFID tag and the first receiving antenna as a function of the first powers in reception of the first identification signals which are associated with the tag identifier of the RFID tag, - calculate a second distance between the RFID tag and the second receiving antenna as a function of the second powers in reception of the second identification signals which are associated with the tag identifier of the RFID tag; and - classify the RFID tag as a central tag (91) or as an external tag (92) also as a function of the first distance and the second distance.
6. Wrapping machine (1) according to claim 5, comprising an inertial unit (6) mounted on the carriage (13) for estimating in real time at least a position, an orientation and a speed of the carriage (13) in the space around the central zone (71), wherein the processing module (5) is connected to the inertial unit (6) in order to receive the position, the orientation and the speed of the carriage (13) and synchronize them with the receptions of the first identification signals from the first reception antenna and the second identification signals from the second reception antenna, and for each RFID tag, among the detectable RFID tags (91, 92), the processing module (5) is configured to establish a location of the RFID tag as a function of the first distance, the second distance and the position, the orientation and the speed of the carriage (13),in order to classify the RFID tag as a central tag (91) or as an external tag (92) also depending on its location.,
7. A wrapping machine (1) according to any preceding claim, wherein the first radio identification reader (3) and the second radio identification reader (4) are configured to interrogate and receive the respective first identification signals and second identification signals alternately.
8. Wrapping machine (1) according to any one of the preceding claims, in which a support (20) is fixed on the carriage (13) and has an internal face (21) facing the central zone (71), and an external face (22), opposite the internal face (21), and the first antenna receiving antenna is turned towards the central zone (71) by being fixed on said internal face (21) of the support (20), and the second receiving antenna is turned in a direction opposite to the central zone (71) by being fixed on said external face (22) of the support (20).
9. A wrapping machine (1) according to any preceding claim, wherein the at least one first radio identification reader (3) comprises a plurality of first radio identification readers (3).
10. A method of wrapping loads (81) on a pallet (80) by means of a wrapping machine (1) according to any one of the preceding claims, and during which the radio-identification system (2) interrogates and receives identification signals from detectable RFID tags (91, 92), associated with respective tag identifiers, over several revolutions of the carriage (13) during a wrapping operation, with the following steps: - interrogating and receiving over the several revolutions of the carriage (13) first identification signals among the identification signals, by the first receiving antenna of the at least one first radio-identification reader (3);- interrogation and reception on the several revolutions of the carriage (13) of second identification signals among the identification signals, by the second reception antenna of the at least one second radio-identification reader (4); - reception by the processing module (5) of the first identification signals and the second identification signals; - inventory of each RFID tag, among the detectable RFID tags (91, 92), by analyzing and comparing the first identification signals and the second identification signals which are associated with the tag identifier of said RFID tag in order to classify said RFID tag as being a central tag (91) located in the central zone (71) by being fixed on a load (81) to be wrapped or as being an external tag (92) located outside the central zone (71).;