A device for identifying or tracking tools and a roller cabinet including the device

Abstract

An apparatus for identifying or tracking a tool includes: a first wall (50) defining a first area in which a first tool, including an RFID tag, can be placed; a first antenna (1) for receiving a first radio signal from the RFID tag when the first tool is in the first area and for generating a first analog signal based on the first radio signal; a first analog-to-digital converter (16) for converting the first analog signal into a digital signal; a first processing unit (22, 24) for processing the digital signal; a first housing (4) housing the first processing unit; a second housing (18) housing the first ADC, the second housing being located away from the first housing; and a digital link (10) connecting the first housing and the second housing for transmitting the digital signal to the first processing unit.

Description

Technical Field

[0001] The present invention relates to a device for identifying or tracking a tool. Background Art

[0002] A cabinet including a system for tracking or identifying tools equipped with RFID tags has been proposed. RFID tags are passive elements (in the sense that the tool equipped with the RFID tag does not include any internal power source for powering the RFID tag).

[0003] The system includes two antennas for communicating with the RFID tags of any tools secured in the cabinet: a first antenna is disposed at the top of the cabinet and a second antenna is disposed at the bottom of the cabinet.

[0004] The system also includes a housing containing a processing unit and an analog-to-digital converter (ADC). The processing unit and the ADC are usually different parts of the same electronic circuit. The processing unit and the ADC are connected to each other using a very short digital link.

[0005] The cabinet includes a housing defining a cavity. A drawer is arranged in the cavity and is movable relative to the housing. A housing accommodating a processing unit and an ADC is fixed to the housing. The ADC is connected to each antenna via an analog cable (coaxial type) that is much longer than a digital cable.

[0006] To check whether a tool is fixed in a cabinet, the system's antenna transmits a request radio signal. The RFID tag of a tool located near one of the antennas receives the request radio signal and transmits a response radio signal carrying information about the tool. The response signal is picked up by the antenna, which converts it into an analog signal. The analog signal is then transmitted to the ADC via a coaxial cable and converted into a digital signal by the ADC. The processing unit then processes the digital signal to identify the tool that transmitted the response.

[0007] A problem that arises in the above cabinet is that the radio signal emitted by the tool and then picked up by the antenna may be obscured by the interference caused by each coaxial cable. Therefore, this interference may prevent the processing unit from identifying the tool that issued the response. Summary of the invention

[0008] A first object of the invention is to propose a system for tracking or identifying tools that is less susceptible to interference.

[0009] The present invention proposes a device for identifying or tracking tools. The device comprises: a first wall (50) defining a first area, wherein a first tool including an RFID tag can be placed in the first area; a first antenna (1), wherein the first antenna (1) is used to receive a first radio signal from the RFID tag when the first tool is in the first area, and to generate a first analog signal according to the first radio signal; a first analog-to-digital converter (16) for converting the first analog signal into a digital signal; a first processing unit (22, 24) for processing the digital signal; a first housing (4) accommodating the first processing unit; a second housing (18) accommodating the first analog-to-digital converter, wherein the second housing is remote from the first housing; and a digital link (10) connecting the first housing and the second housing for transmitting the digital signal to the first processing unit.

[0010] In the device of the present invention, the ADC and the processing unit are housed in two separate housings, which can be placed away from each other. Therefore, the total length of the analog cable can be shortened, and the digital cable connecting the two housings can be much longer than the analog cable. Digital cables cause less interference than analog cables. That is why this arrangement allows reducing interference in the system.

[0011] The device according to the invention may also comprise optional features.

[0012] The first wall and / or the second housing may be movable relative to the first housing.

[0013] The second housing can be capable of being placed in: a first position relative to the first housing, wherein the first analog-to-digital converter is connected to the digital link to allow the digital signal to be transmitted to the first processing unit; and a second position relative to the first housing, wherein the first analog-to-digital converter is disconnected from the digital link to prevent the digital signal from being transmitted to the first processing unit.

[0014] The device may further comprise a first drawer comprising the first wall and the second housing, the first wall being, for example, a bottom wall of the first drawer on which the first tool can rest.

[0015] The first position may be a closed position of the first drawer (36), and wherein the second position is an open position of the first drawer.

[0016] The first drawer may comprise a back portion, to which the first analog-to-digital converter is attached, for example adhesively attached.

[0017] The first wall may be metallic, and wherein the first antenna is a slot antenna cut in the first wall.

[0018] The device may further include a first control unit configured to set the first antenna to have a first frequency value and a first power value that satisfy the following criteria: (1) the first frequency value is selected within a predetermined range of RFID frequencies and maximizes the power of the first radio signal transmitted by the RFID tag in response to a request signal transmitted by the first antenna, and (2) the first power is a minimum power value that enables the first antenna set to the selected first frequency value to effectively detect the response signal so that information about the first tool can be extracted from the first radio signal. The minimum value enables the first antenna set to the selected frequency value to effectively detect the first radio signal, thereby enabling information about the first tool to be extracted therefrom.

[0019] The first control unit can be configured to perform the following steps: at a first time when the first tool is in the first area, determine the first frequency value and the first power value by testing different values ​​and different power values ​​within the predetermined range of the RFID frequency; at a second time after the first time, set the first antenna to have the first frequency value and the first power value determined at the first time, attempt to extract the information about the first tool from the first radio signal, and repeat the determination step only when the attempt fails.

[0020] The device may also include: a second wall defining a second area, wherein a second tool including an RFID tag can be placed in the second area when the first tool is in the first area; a second antenna, the second antenna being used to receive a second radio signal from the RFID tag of the second tool when the second tool is in the second area, and being used to generate a second analog signal based on the second radio signal; a second analog-to-digital converter (16) being used to convert the second analog signal into a second digital signal; a second processing unit being used to process the second digital signal; a third housing accommodating the second processing unit; a fourth housing accommodating the second analog-to-digital converter, the fourth housing being away from the third housing; and a second digital link connecting the third housing and the fourth housing, being used to transmit the second digital signal to the second processing unit.

[0021] The first housing and the third housing may be the same housing or fixed relative to each other.

[0022] The second wall and / or the fourth housing may be movable relative to the third housing.

[0023] The fourth housing can be capable of being placed in: a third position relative to the third housing, wherein the second analog-to-digital converter is connected to the second digital link to allow the second digital signal to be transmitted to the second processing unit; and a fourth position relative to the third housing, wherein the second analog-to-digital converter is disconnected from the second digital link to prevent the second digital signal from being transmitted to the second processing unit.

[0024] The device may further comprise a second drawer comprising the second wall and the fourth housing, wherein the second drawer is different from the first drawer, the second wall being, for example, a bottom wall of the second drawer, on which the second tool can rest.

[0025] The third position may be a closed position of the second drawer, and wherein the fourth position is an open position of the second drawer.

[0026] The second drawer may comprise a back portion, the second analog-to-digital converter being attached to the back portion of the second drawer, for example being adhered to the back portion.

[0027] The second wall may be metallic, and wherein the second antenna is a slot antenna cut in the second wall.

[0028] The device may further include a second control unit configured to set the second antenna to have a second frequency value and a second power value that satisfy the following criteria: (1) the second frequency value is selected within a predetermined range of RFID frequencies and maximizes the power of the second radio signal transmitted by the RFID tag in response to the request signal transmitted by the second antenna; (2) the second power value is a minimum value that enables the second antenna set to the selected frequency value to effectively detect the response signal so that information about the second tool can be extracted from the second radio signal. The minimum value enables the second antenna set to the selected frequency value to effectively detect the second radio signal so that information about the second tool can be extracted therefrom.

[0029] The second control unit can be configured to perform the following steps: at a third time when the second tool is in the second area, determine the second frequency value and the second power value by testing different values ​​and different power values ​​within the predetermined range of the RFID frequency; at a fourth time after the third time, set the second antenna to have the second frequency value and the second power value determined at the third time, attempt to extract the information about the second tool from the second radio signal, and repeat the determination step only when the attempt fails.

[0030] A roller cabinet may include the device for identifying or tracking tools according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Further details, features and advantages of the invention are explained in more detail below with the aid of exemplary embodiments of the invention shown in the drawings, in which:

[0032] Figure 1 is a schematic diagram of a system for identifying or tracking a tool according to an embodiment of the present invention.

[0033] Figure 2 According to an embodiment of the present invention Figure 1 Schematic diagram of the slave module of the system.

[0034] Figure 3 According to an embodiment of the present invention Figure 2 The slave module perspective.

[0035] Figure 4 According to an embodiment of the present invention Figure 1 Schematic diagram of the master module 4 of the system.

[0036] Figure 5 is a side view of a roller cabinet according to an embodiment of the present invention.

[0037] Figure 6 is a perspective view of a housing of a roller cabinet according to an embodiment of the present invention.

[0038] Figure 7 and 8 2 are two different perspective views of a drawer of a roller cabinet according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] 1 / System for identifying or tracking tools

[0040] refer to Figure 1, a system for identifying or tracking tools equipped with RFID tags includes a plurality of antennas 1 for communicating with the RFID tags, a plurality of slave modules 2, and a master module 4.

[0041] Each antenna 1 is configured to communicate with an RFID tag. Each antenna can send a request radio signal to the RFID tag and receive a response radio signal emitted by the RFID tag.

[0042] Each slave module 2 (hereinafter referred to as RF head) is connected to at least an antenna 1 through an analog link 6 (such as a coaxial cable). The slave module can be connected to a single antenna 1 or to a plurality of antennas 1 using at least one analog link 6.

[0043] The main module 4 is connected to each RF head 2 via at least one power link 8 and at least one data link 10 .

[0044] Each power link 8 is configured to provide power to the RF head 2 .

[0045] Each data link 10 is a digital link configured to transmit digital signals from the RF head 2 to the main module 4 , and to transmit digital signals from the main module 4 to at least one RF head 2 .

[0046] refer to Figure 2 , the RF head 2 includes an interface 12 for communicating with at least one antenna, a power supply unit 14 and a converter unit 16.

[0047] The interface 12 is connected via an analog link 6 at least to the antenna 1 .

[0048] The power supply 14 is connected to the main module 4 via a power link 8. When the power supply unit 14 receives power via the power link 8, it provides power to all other electronic components of the RF head 2 and to each antenna 1 connected to the RF head 2 via the interface 12.

[0049] The converter unit 16 is connected to the main module 4 via at least one data link.

[0050] The converter unit 16 comprises an analog-to-digital converter (ADC) configured to convert an analog signal acquired by the antenna and received by the interface into a digital signal and to send the digital signal to the main module 4 via the digital link 10 .

[0051] The converter unit 16 may also include a digital-to-analog converter (DAC). The DAC is configured to convert a digital signal from the data link 10 into an analog signal and send the analog signal to the interface 12 so that the interface 12 can then send the analog signal to the antenna 1.

[0052] Reference Figure 3 The RF head 2 includes a housing 18 that accommodates all of the above-mentioned electronic components 12, 14, 16. These electronic components are generally included in the Figure 3 In the common circuit shown.

[0053] The housing 18 may include two parts: a base 18 a and a cover 18 b , which may be secured to each other to close the housing 18 .

[0054] The housing 18 also includes a plurality of ports 20 , each port 20 being designed to be connected to a power link 8 and a data link 10 .

[0055] Now go to Figure 4 The main module 4 comprises a power management unit 22, a processing unit 24 and means 26, 28 for accessing a tool database.

[0056] The tool database is not stored in the main module 4, but in the memory of the server outside the roller cabinet. The means for accessing the tool database may include a communication interface for accessing the external database, for example, a wireless communication interface 26 (Wi-Fi, Bluetooth, etc.) and / or a wired communication interface 28.

[0057] Alternatively, the means for accessing the tool database comprise a memory contained in the main module 4, in which the tool database is stored. This memory may be of any type: HDD, SSD, Flash memory, etc.

[0058] The power management unit 22 is configured to supply power to the RF head 2 via the power link 8 and to supply power to other electrical components 24, 26 of the main module 4. The power management unit 22 may include a battery for supplying power and / or may be connected to an external power source via a universal power link 30.

[0059] The processing unit 24 is connected to the data link and is configured to process the digital signal transmitted by the data link.

[0060] Generally speaking, the system comprises a control unit configured to set the frequency and power for each antenna. The control unit is, for example, a separate power management unit 22, or a combination of the power management unit 22 and the processing unit 24. The control unit can allocate different powers / frequencies to different antennas 1.

[0061] The tool database includes a plurality of entries, each entry including a tool identifier that may be associated with other information about the tool.

[0062] Figure 4All electronic components of the main module 4 shown in FIG. 4 can typically be integrated in a common circuit of the motherboard type.

[0063] 2 / Roller cabinets including systems for identifying or tracking tools

[0064] Reference Figure 5 and 6 , a roller cabinet 32 ​​for storing tools includes the above-mentioned system for tracking or identifying tools.

[0065] The roller cabinet 32 ​​includes a housing 34 and a plurality of drawers 36. The plurality of drawers may include at least three drawers, for example, Figure 5 Seven drawers shown.

[0066] The roller cabinet 32 ​​further includes wheels 38 mounted on the housing 34 for moving the roller cabinet.

[0067] like Figure 6 As shown, the housing 34 defines an interior cavity of the roller cabinet 32 ​​.

[0068] The housing 34 includes a top wall 40 , a bottom wall 42 , a rear wall 44 , and two side walls 46 , 48 .

[0069] The cavity is defined between the two side walls 46 , 48 and between the top wall 40 and the bottom wall 42 .

[0070] The main module 4 is fixed to the housing. Figure 6 In the embodiment shown, the main module 4 is fixed to the inner surface of the rear wall 44 .

[0071] The power link 8 and the digital link 10 are also fixed to the inner surface of the rear wall 44. The links 8, 10 extend parallel to each other and vertically in the cavity defined by the housing 34.

[0072] The drawers 36 are stacked vertically within the cavity defined by the housing 34 .

[0073] Each drawer 36 is movable relative to the housing 34. More precisely, each drawer 36 is arranged in the cavity and can slide between a closed position and an open position relative to the housing 34. In the closed position, the drawer is completely covered by the top wall 40 and is electrically connected to the links 8 and 10. In the open position, the drawer 36 is separated from the rear wall 44 and the electrical connection with the links 8 and 10 is also disconnected.

[0074] like Figure 7 and Figure 8 As shown, the drawer 36 includes a horizontally extending bottom wall 50 , and the following walls extending vertically and connected to the bottom wall: a front wall 52 , a rear wall 54 , and two side walls 56 , 58 .

[0075] Drawer 36 defines an area in which tools can be placed as long as drawer 36 is in an open position. When first drawer 36 is in its closed position, any tools placed therein are secured in roller cabinet 32.

[0076] The area is defined between the front wall 52 and the rear wall 54, and between the two side walls 56, 58. Each of the walls 50, 52, 54, 56, 58 delimits the area.

[0077] Tools placed in this area rest on the bottom wall 50 .

[0078] The bottom wall comprises an upper surface and a lower surface opposite to the upper surface. The bottom wall is rectangular.

[0079] At least one antenna 1 of the system is a slot antenna cut into a metal wall defining an area where a tool can be placed.

[0080] This arrangement is advantageous for a number of reasons: firstly, communication between the first (slot) antenna and the RFID tags of tools placed in the first area defined in the first drawer is particularly efficient; secondly, no expensive separate antenna needs to be included in the system.

[0081] exist Figure 7 and Figure 8 In the illustrated embodiment, the metal wall in which at least one slot antenna 1 is cut out is the bottom wall 50 .

[0082] The slot antenna 1 includes at least one slot opening in two opposite surfaces of a metal wall (eg, an upper surface and a lower surface of a bottom wall).

[0083] The dimensions (length, width) of the slot of the antenna 1 define the range of RFID frequencies that can be used by the slot antenna for radio communication with an RFID tag of a tool.

[0084] More than one slot antenna 1 may be cut in the metal wall. Figure 7 and Figure 8 In the embodiment depicted in FIG, eight slot antennas 1 are cut into the bottom wall 50 of the drawer 36. The slots may extend diagonally relative to the rear wall and the side walls.

[0085] Furthermore, the RF head 2 of the system is fixed to the drawer 36 .

[0086] An analog link 6 connecting the antenna 1 of the drawer 36 to the RF head 2 fixed to the same drawer 36 extends on the lower surface of the bottom wall 50 of the drawer 36 .

[0087] As mentioned in the introduction, analog links, in particular coaxial cables, are prone to interference. It is advantageous to fix the RF head 2 to the drawer 36 because the analog link can be short. Therefore, the potential interference caused by such an analog link 6 is limited.

[0088] More specifically, the RF head 2 is secured to the rear wall 54 of the drawer 36 such that the port 20 of the RF head 2 faces the rear wall 44 of the housing 34 .

[0089] When the drawer 36 is in its closed position, the port 20 of the RF head contacts the data / power links 8, 10. In other words, in the closed position, data can be exchanged between the RF head 2 and the main module 4 using at least one digital link 10, and the main module 4 can use the power link 8 to supply power to the RF head.

[0090] When the drawer 36 is open, the port 20 is disconnected from the data / power links 8, 10. In other words, in the open position, data cannot be exchanged between the RF head and the main module 4, and the main module 4 does not supply power to the RF head.

[0091] according to Figure 7 and Figure 8 In the arrangement shown, each drawer 36 of the roller cabinet 32 ​​includes an RF head 2 and at least one antenna 1. For example, Figure 5 An embodiment is shown in which the roller cabinet 32 ​​includes seven drawers 26 and seven RF heads 2 , each RF head 2 being secured to a respective drawer 36 .

[0092] 3 / Method for identifying or tracking a tool comprising an RFID tag

[0093] Let M be the number of predetermined tools to be secured in the roller cabinet.

[0094] Each tool can be of any type: screwdriver, hammer, pliers, etc.

[0095] Each tool includes an RFID tag. The RFID tag includes a memory that stores information about the tool, including the tool identifier. The RFID tag is able to communicate with any antenna 1 of the system. The RFID tag is passive in that it does not include any internal power source.

[0096] Each tool should fit in one drawer, for example, only in one drawer. Preferably, at least one drawer 36 (or each drawer 36) of the roller cabinet houses a tool organizer. Each tool organizer defines at least one cavity for accommodating one of the M tools. The shape of each cavity is complementary to the shape of one of the M tools.

[0097] In a preliminary step, M tools are registered in a database. For each tool, a tool entry is created in the database, the tool entry comprising at least:

[0098] A unique identifier for the tool,

[0099] The unique identifier of the drawer in which the tool is installed,

[0100] A unique identifier of the best antenna 1 used to communicate with the tool when the tool is placed in the reference drawer (how this best antenna is determined will be described later). It should be noted that the best antenna is not necessarily part of the drawer in which the tool is assembled; instead, the best antenna can be part of another drawer of the roller cabinet.

[0101] a predetermined frequency value, and

[0102] Predetermined power value.

[0103] The configuration of each drawer 36 may also be registered in the database. For example, a drawer entry is created for each drawer 36, the drawer entry including: a unique identifier of the drawer, and a unique identifier of each antenna 1 included in the drawer.

[0104] By convention, data within entries of a database are said to be associated with each other.

[0105] To check whether any one of the M tools is present in the roller cabinet, the system performs the following steps.

[0106] The processing unit detects that the drawer has reached its closed position (this drawer is hereinafter referred to as the "reference drawer"). For example, the detection includes detecting a first time period during which no signal is received from the RF head 2 of the reference drawer 36 (which means that the RF head 2 is disconnected from the main module), and then detecting a second time period during which a signal from the RF head 2 of the reference drawer 36 is received by the processing unit (which means that the RF head 2 has just been reconnected to the main module).

[0107] When detecting that the reference drawer 36 is closed, the processing unit determines all tools assembled in the reference drawer that has just been closed. For this reason, the processing unit accesses the database and searches for the tool entry containing the unique identifier of the reference drawer 36.

[0108] For each tool fitted in the reference drawer, the processing unit performs the following sub-steps.

[0109] The processing unit determines the antenna 1 to be used for communication with the tool. To do this, the processing unit accesses the database and reads the unique identifier of the best antenna 1 associated with said tool in the tool entry.

[0110] As previously mentioned, this best antenna 1 does not have to be part of the reference drawer itself. Therefore, the processing unit then determines the drawer 36 comprising the best antenna 1 associated with the tool. To do this, the processing unit parses the drawer entries registered in the database.

[0111] Then, the control unit of the main module 4 supplies the best antenna 1 with an amount of power corresponding to the power value associated with the best antenna 1 in the database. To this end, the control unit sends power to the RF head 2 of the drawer 36 including the best antenna 1 through the power link 8. Then, the RF head 2 supplies power to the best antenna 1.

[0112] Furthermore, the control unit sets the best antenna 1 to have a predetermined frequency associated with the best antenna 1 in the database.

[0113] Best antenna 1 sends a request radio signal and waits for a response signal.

[0114] If the tool with which the best antenna 1 should communicate is actually present in the reference drawer 36, the RFID tag of the tool receives the request signal and transmits a response radio signal in response to the request signal, the response signal carrying information about the tool, including a unique identifier of the tool. The best antenna 1 then receives the response signal, converts it into an analog signal, and transmits the analog signal to the RF head 2 via the analog link 6. The ADC contained in the RF head 2 converts the analog signal into a digital signal, which is then transmitted to the main module via the digital link. The processing unit extracts the unique identifier of the tool from the digital signal. The processing unit then accesses the database and compares the extracted unique identifier with the tool identifier associated with the best antenna in the database. If the two tool identifiers match, the processing unit 24 generates a message indicating that the tool is present in the roller cabinet 32, or more specifically, in the reference drawer 36.

[0115] If the best antenna 1 does not receive any response signal and / or if the tool identifiers compared by the processing unit do not match, the processing unit 24 generates a message indicating that the tool is not in the roller cabinet 32 ​​, or more specifically, not in the reference drawer 36 .

[0116] Any message generated by the processing unit may be sent to a user terminal including a display screen so that the message is displayed on the display screen.

[0117] The above steps are repeated for each tool assembled in the reference drawer 36 .

[0118] 4 / Adaptive frequency and power

[0119] Basically, any antenna 1 of the system can use different frequency values ​​and different power values ​​to communicate with the RFID tags of the tools placed in the drawer 36. The RFID tag of any tool is a passive element. The power of the response signal emitted by the RFID tag depends on the power used by the antenna to send the request signal.

[0120] If the antenna 1 has been set to a very low power and / or an inappropriate frequency, it may not be possible to correctly extract information from the response signal picked up by the antenna.

[0121] Furthermore, setting the system's antenna to very high power is energy consuming.

[0122] It should also be noted that not all RFID frequencies that the antenna 1 can use to communicate with RFID tags are equally efficient. In fact, the power required by the antenna 1 to allow proper extraction of the information carried by the response signal depends on the frequency used by said antenna 1 to send the request signal.

[0123] Additionally, multiple antennas 1 configured to use the same power and the same frequency are not equally effective for communicating with tools placed in drawer 36 because the antennas have different locations. An antenna 1 very close to a tool tends to communicate more effectively than another antenna further away from the tool.

[0124] As described above, when the reference drawer is closed, the system attempts to communicate with each tool mounted in the reference drawer through the associated best antenna 1 and the associated power / frequency values ​​stored in the database. These best antennas 1 and the power / frequency parameters they use are determined in a preliminary calibration step comprising the following sub-steps.

[0125] The M tools are placed in their respective fiducial reference drawers 36, and all drawers 36 are closed.

[0126] The system determines a frequency value Fij and a first power value Pij used by the i-th antenna of the system to communicate with the j-th tool fixed in the roller cabinet 32, wherein the frequency value Fij and the power value Pij meet the following criteria:

[0127] The frequency value Fij is selected within a predetermined range of RFID frequencies that the antenna can use, and F maximizes the power of a response signal transmitted by the RFID tag of the tool in response to a request radio signal transmitted by the antenna.

[0128] The power value Pij is the minimum value that enables the antenna configured with the selected frequency value to effectively detect the response signal so that information about the tool can be extracted from the response signal.

[0129] The control unit tests different frequency values ​​and different power values ​​to determine Fij, Pij.

[0130] The control unit may, for example, set the i-th antenna with the lowest frequency of the RFID frequency range and with a very low power. At this point, since the power set is too low, no information can be extracted from the response signal acquired by the i-th antenna and then processed by the processing unit. The control unit gradually increases the power value used by the i-th antenna. At a certain point, the power set in the i-th antenna becomes high enough to allow data to be extracted from the response signal acquired by the i-th antenna. Alternatively, the control unit may set the i-th antenna to a high power and then gradually reduce the power value used by the i-th antenna. At a certain point, the power set in the i-th antenna becomes too small to correctly extract information from the response signal acquired by the i-th antenna.

[0131] The minimum power that allows such extraction is stored in the memory in association with the frequency. The control unit repeats the above steps for frequency values ​​included in the RFID frequency range. As a result, although a plurality of minimum powers are stored in the memory, each minimum power is associated with a frequency. The control unit selects the minimum value among the minimum power values ​​stored in the memory so far as the power Pij, and selects the frequency associated with the minimum value as the frequency Fij.

[0132] The determination step is repeated for each antenna (for i from 1 to N) and for each tool (for j from 1 to M). In other words, the determination step is performed NM times.

[0133] At this stage, each tool j is associated with N pairs of parameters (Pij, Fij), each pair of parameters being associated with antenna i. Among these pairs, there is a pair that includes the minimum power; the antenna associated with this minimum power is selected by the system as the best antenna. The unique identifier of the selected best antenna and the Pij and Fij values ​​determined for this best antenna are written into the tool entry of the jth tool.

[0134] The calibration step may for example be performed only once in a period of time, such as once a day or once a week.

[0135] Once the calibration step is completed, each time the drawer 36 is closed, the method described in section 3 / is performed to check whether a tool is present in the roller cabinet.

[0136] If the system concludes that a given tool is present in a drawer that has just been closed, the calibration step is not performed. This is advantageous because calibration is time consuming.

[0137] The system may sometimes fail to correctly detect a tool placed back in its reference drawer due to the local environment of the tool. For example, the best antenna 1 may not be able to receive the response signal sent by the tool due to some obstacle (such as another tool) that was not present in the reference drawer when the calibration step was performed but is now present in the reference drawer.

[0138] To avoid such false detections, if the system concludes that a given tool is not present in its reference drawer, the system advantageously attempts to update the optimal frequency and the optimal frequency associated with the tool and associated with the corresponding optimal antenna stored in the database. During this update, the system tests different frequency values ​​and / or power values, as during the calibration step. However, the number of frequencies tested during the update step and / or the number of power values ​​tested is preferably smaller than during the calibration step, so that the update is shorter than the calibration step.

Claims

1. A device for identifying or tracking a tool, the device comprising: a first wall (50) defining a first area in which a first tool including an RFID tag can be placed, a first antenna (1), the first antenna (1) being used to receive a first radio signal from the RFID tag when the first tool is in the first area, and to generate a first analog signal based on the first radio signal, a first analog-to-digital converter (16) for converting the first analog signal into a digital signal, a main module (4), the main module (4) comprising a first processing unit (24) for processing the digital signal, and a first housing, the first housing accommodating the first processing unit (24), Features: The first wall (50) is the bottom wall of the drawer (36), and the drawer (36) includes a front wall (52), a rear wall (54) and two side walls (56), (58) in addition to the bottom wall. wherein the drawer (36) is movable relative to the housing (34) between a closed position and an open position, The drawer (36) comprises the first antenna (1) and an RF head (2), the RF head (2) comprising an interface (12) for communicating with at least one antenna, a power supply unit (14), the first analog-to-digital converter (16), a second housing (18) and a port (20), wherein the RF head (2) is fixed to the rear wall (54) of the drawer (36), and the port (20) of the RF head (2) faces the rear wall (44) of the housing (34), wherein, when the drawer (36) is in the closed position, the port (20) of the RF head (2) is connected to a data link (10) and a power link (8), so that data is exchanged between the RF head (2) and the main module (4), Furthermore, when the drawer (36) is in the open position, the port (20) of the RF head (2) is disconnected from the data link (10) and the power link (8), and data cannot be exchanged between the RF head (2) and the main module (4).

2. The device according to the preceding claim, wherein The data link (10) and the power link (8) are fixed to the rear wall (44) of the housing (34), wherein the main module (4) is fixed to the inner surface of the rear wall (44) of the housing, and / or wherein the second housing (18) is movable relative to the first housing.

3. Device according to the preceding claim, wherein The second housing (18) can be placed: a first position relative to the first housing, wherein the first analog-to-digital converter (16) is connected to the data link (10) as a digital link to allow the digital signal to be transmitted to the first processing unit, and A second position relative to the first housing wherein the first analog-to-digital converter (16) is disconnected from the digital link to prevent the digital signal from being transmitted to the first processing unit.

4. The device according to claim 1, wherein: The first tool is restable on the bottom wall, and the first processing unit is configured to detect whether the drawer has reached the closed position and to determine all tools assembled in the drawer that has just been closed.

5. The device according to claim 3, wherein: The first position is the closed position of the drawer (36), and wherein the second position is the open position of the drawer (36).

6. An apparatus according to claim 1, wherein the apparatus comprises a plurality of drawers (36) stacked vertically in a cavity defined by the shell (34), and each of the drawers (36) comprises the RF head (2) and at least one of the first antennas (1), and the RF head (2) is fixed to the drawer (36).

7. The device according to claim 1, wherein: The first wall (50) is metal, and a tool placed in the first area rests on the bottom wall, and wherein the first antenna (1) is a slot antenna cut into the first wall (50).

8. The apparatus according to claim 1, further comprising a first control unit configured to set the first antenna to have a first frequency value and a first power value that satisfy the following criteria: The first frequency value is selected within a predetermined range of RFID frequencies and maximizes the power of the first radio signal transmitted by the RFID tag in response to a request signal transmitted by the first antenna, The first power value is a minimum power value at which the first antenna, when set at the selected frequency value, can effectively detect the first radio signal to extract information about the first tool therefrom.

9. Device according to the preceding claim, wherein The first control unit is configured to perform the following determination steps: determining the first frequency value and the first power value by testing different values ​​of the RFID frequency and different power values ​​within the predetermined range at a first time when the first tool is in the first area, At a second time after the first time, setting the first antenna to have the first frequency value and the first power value determined at the first time, attempting to extract the information about the first tool from the first radio signal, and repeating the determining step only if the attempt fails.

10. The apparatus according to claim 1, further comprising: a second wall defining a second area, wherein a second tool including an RFID tag can be placed in the second area when the first tool is in the first area, a second antenna for receiving a second radio signal from the RFID tag of the second tool when the second tool is in the second area, and for generating a second analog signal based on the second radio signal, a second analog-to-digital converter, configured to convert the second analog signal into a second digital signal, a second processing unit, configured to process the second digital signal, a third housing accommodating the second processing unit, a fourth housing accommodating the second analog-to-digital converter, the fourth housing being away from the third housing, A second digital link connects the third housing and the fourth housing and is used to transmit the second digital signal to the second processing unit.

11. Device according to the preceding claim, wherein The first housing and the third housing are the same housing or are fixed relative to each other.

12. The device according to any one of claims 10 and 11, wherein: The second wall and / or the fourth housing are movable relative to the third housing.

13. Device according to the preceding claim, wherein The fourth housing can be placed: a third position relative to the third housing, wherein the second analog-to-digital converter is connected to the second digital link to allow the second digital signal to be transmitted to the second processing unit, and and a fourth position relative to the third housing, wherein the second analog-to-digital converter is disconnected from the second digital link to prevent the second digital signal from being transmitted to the second processing unit.

14. The apparatus of claim 13, further comprising a second drawer, the second drawer comprising the second wall and the fourth housing, wherein: The second drawer is different from the drawer, the second wall is a bottom wall of the second drawer, and the second tool can be placed on the bottom wall.

15. The device according to claim 14, wherein: The third position is a closed position of the second drawer, and wherein the fourth position is an open position of the second drawer.

16. The device according to claim 14, wherein: The second drawer includes a back portion, and the second analog-to-digital converter is attached to the back portion of the second drawer.

17. The device according to claim 10, wherein: The second wall is metallic, and wherein the second antenna is a slot antenna cut into the second wall.

18. The apparatus according to claim 10, further comprising a second control unit configured to set the second antenna to have a second frequency value and a second power value that satisfy the following criteria: The second frequency value is selected within a predetermined range of RFID frequencies and maximizes the power of the second radio signal transmitted by the RFID tag in response to the request signal transmitted by the second antenna, The second power value is a minimum value at which the second antenna can effectively detect the second radio signal when the second antenna is set at the selected frequency value, so as to extract information about the second tool from the second radio signal.

19. Device according to the preceding claim, wherein The second control unit is configured to perform the following determination steps: determining the second frequency value and the second power value by testing different values ​​and different power values ​​within the predetermined range of the RFID frequency at a third time when the second tool is in the second area, At a fourth time after the third time, setting the second antenna to have the second frequency value and the second power value determined at the third time, attempting to extract the information about the second tool from the second radio signal, and repeating the determining step only if the attempt fails.

20. A roller cabinet comprising a device for identifying or tracking tools according to any one of the preceding claims 1 to 9, wherein the housing (34) defines a cavity and the drawer (36) is arranged in the cavity, wherein: The main module (4) is connected to the RF head (2) via at least one power link (8) and at least one data link (10), wherein the power link (8) is configured to provide power to the RF head (2), and the data link (10) is a digital link configured to transmit digital signals from the RF head (2) to the main module (4), and to transmit digital signals from the main module (4) to the RF head (2).

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