Device for identifying or tracking tool and roller cabinet comprising same

Abstract

An apparatus for identifying or tracking a tool, the apparatus comprising a metal wall defining a first region in which a first tool comprising an RFID tag can be placed, an antenna to communicate with the RFID tag whenever the first tool is in the first region, where the antenna is a slot antenna cut out in the metal wall.

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. The RFID tag is a passive element (in the sense that the tool equipped with the RFID tag does not include any internal power supply for powering the RFID tag). The system includes two antennas for communicating with the RFID tag of any tool fixed in the cabinet: a first antenna is arranged at the top of the cabinet and a second antenna is arranged at the bottom of the cabinet.

[0003] To check whether a tool is fixed in a cabinet, the system's antennas transmit 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. The system can then extract the information to identify the tool that transmitted the response.

[0004] However, the system may not detect that a tool is secured in the cabinet when the response signal emitted by the tool's RFID tag and then received by the antenna is too weak.

[0005] The quality of the response signal picked up by the antenna actually depends on the settings used by the antenna transmitting the request radio signal (in particular the power and frequency used by the antenna to send the request radio signal).

[0006] When the tool is actually present in the cabinet, the quality of the response signal acquired by the antenna also depends on the environment of the tool. Some obstacles located between the tool and the antenna may hinder the propagation of the response radio signal. The metal walls that define the cavity in which the tool is placed can also hinder this propagation.

[0007] To avoid missed detection, the power used by the antenna to transmit the request radio signal can be increased. However, this solution is energy consuming. 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 missed detections and does not require high energy.

[0009] To this end, a device for identifying or tracking a tool according to a first aspect is proposed. The device comprises: a first metal wall, which defines a first area, in which a first tool including an RFID tag can be placed; a first antenna (1), which is used to communicate with the RFID tag whenever the first tool is in the first area, and the first antenna is a slot antenna cut in the first metal wall.

[0010] Basically, a metal wall is a harsh environment that is susceptible to RF interference. Defining a slot in such a metal wall to obtain a slot antenna actually converts this harsh environment into an environment in which the response signal emitted by the RFID tag of a tool placed in the area is more efficiently detected. This efficiency gain is obtained without increasing the power level used by the antenna. In addition, the slot antenna is easier to manufacture and cheaper than a standalone antenna.

[0011] The apparatus according to the first aspect may include the optional features described below.

[0012] The device may also include a first analog-to-digital converter, which is used to convert the analog signal obtained by the first antenna into a first digital signal; a first processing unit, which is used to process the digital signal; and a digital link, which is used to transmit the digital signal to the first processing unit.

[0013] The first metal wall and / or the first analog-to-digital converter may be movable relative to the first processing unit.

[0014] The first analog-to-digital converter can be placed in: (1) a first position relative to the first processing unit, 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 (2) a second position relative to the first processing unit, 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.

[0015] The first drawer may comprise the first metal wall, such as a bottom wall of the first drawer (36), on which the first tool can rest.

[0016] The first position may be a closed position of the first drawer, and the second position may be an open position of the drawer (36).

[0017] The first analog-to-digital converter may be secured to the first drawer, for example to a back of the drawer.

[0018] The apparatus 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 a response 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 response signal. The minimum value enables the first antenna configured with the selected frequency value to effectively detect the response signal so that information about the first tool can be extracted from the response signal.

[0019] The first control unit may be configured to perform the following steps: (1) 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 ​​within the predetermined range of the RFID frequency and different values ​​within the power range, (2) 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 response signal, and repeat the determination step only if the attempt fails.

[0020] The device may also include: a second metal wall that defines a second area, and when the first tool is placed in the first area, a second tool including an RFID tag can be placed in the second area; a second antenna that is used to communicate with the RFID tag whenever the second tool is in the second area, wherein the second antenna is a slot antenna cut in the second metal wall.

[0021] The device may also include: a second analog-to-digital converter, which is used to convert the analog signal obtained by the second antenna into a second digital signal; a second processing unit, which is used to process the second digital signal; and a second digital link, which is used to transmit the second digital signal to the second processing unit.

[0022] The second wall and / or the second analog-to-digital converter may be movable relative to the second processing unit.

[0023] The second analog-to-digital converter can be placed in: a third position relative to the second processing unit, 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 second processing unit, 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 different from the first drawer, wherein the second drawer comprises the second metal wall, the second metal 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 first analog-to-digital converter may be secured to the first drawer, for example to a back of the drawer.

[0027] The apparatus 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 a response signal transmitted by the RFID tag of the second tool in response to a 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 response signal. The minimum value 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 response signal.

[0028] 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 first 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.

[0029] A roller cabinet may include a device for identifying or tracking tools according to the first aspect of the invention.

[0030] A second object of the present invention is to reduce the amount of power required to detect the presence of a tool in a predetermined area.

[0031] To this end, a device for identifying or tracking a tool according to a second aspect is proposed. The device according to the second aspect comprises:

[0032] a first wall defining a first area in which a first tool including an RFID tag may be placed,

[0033] a first antenna for communicating with the RFID tag whenever the first tool is in the first area, including sending a request signal to the RFID tag and receiving a response signal transmitted by the RFID tag in response to the request signal,

[0034] The first control unit is configured to set the first frequency and the first power of the first antenna to values ​​that satisfy the following criteria:

[0035] The first frequency is selected within a predetermined range of RFID frequencies and maximizes the power of the response signal,

[0036] The first power is a minimum value that enables the first antenna set to the value of the selected first frequency to effectively detect the response signal so that information about the first tool can be extracted from the response signal. The minimum value enables the first antenna set to effectively detect the response signal at a power minimum value at the selected first frequency value, so that information about the first tool can be extracted therefrom.

[0037] The device according to the second aspect may also include the following optional features alone or in combination (when such combination is technically feasible).

[0038] The first control unit may be configured to perform the following steps:

[0039] determining the first frequency value and the first power value by testing different values ​​within a predetermined range of RFID frequencies and different values ​​within a power range at a first time when the first tool is in the first area,

[0040] 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.

[0041] In addition, the number of different frequency values ​​tested when repeating the determination step at the second time may be less than the number of different frequency values ​​tested at the first time, and / or the number of different power values ​​tested when repeating the determination step at the second time may be less than the number of different power values ​​tested at the first time.

[0042] The apparatus according to the second aspect may further include:

[0043] a first analog-to-digital converter (ADC) for converting an analog signal acquired by the first antenna into a first digital signal,

[0044] a first processing unit for processing a digital signal,

[0045] A digital link is used to transmit the digital signal to the first processing unit.

[0046] The first wall and / or the first analog-to-digital converter (ADC) may be movable relative to the first processing unit.

[0047] Preferably, the first analog-to-digital converter (ADC) may be arranged:

[0048] a first position relative to the first processing unit, wherein the first analog-to-digital converter (ADC) is connected to the digital link to allow the digital signal to be transmitted to the first processing unit, and

[0049] A second position relative to the first processing unit, wherein the first analog-to-digital converter (ADC) is disconnected from the digital link to prevent the digital signal from being transmitted to the first processing unit.

[0050] The device according to the second aspect may comprise a first drawer comprising a first wall, such as a bottom wall of the first drawer, on which the first tool may rest.

[0051] The first position may be a closed position of the first drawer, and the second position may be an open position of the drawer.

[0052] A first analog-to-digital converter (ADC) may be secured to the first drawer, for example to a back side of the drawer.

[0053] The first wall may be metallic and the first antenna may be a slot antenna cut in the first wall.

[0054] The apparatus according to the second aspect may further comprise

[0055] a second wall defining a second area, wherein when the first tool is placed in the first area, a second tool including an RFID tag can be placed in the second area,

[0056] a second antenna for communicating with the RFID tag of the second tool whenever the second tool is in the second area,

[0057] A second control unit is configured to set the second antenna to have a second frequency value and a second power value that meet the following criteria:

[0058] The second frequency value is selected within a predetermined range of RFID frequencies and maximizes the power of a response signal transmitted by the RFID tag of the second tool in response to a request signal transmitted by the second antenna,

[0059] 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 response signal. The minimum value enables the second antenna set to the selected second frequency value to effectively detect the response signal at a power minimum value so that information about the second tool can be extracted from it.

[0060] The second control unit may be configured to perform the following steps:

[0061] determining the second frequency value and the second power value by testing different values ​​and different power values ​​within a predetermined range of the RFID frequency at a third time when the second tool is in the second area,

[0062] At a fourth time after the third time, setting the second antenna to 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.

[0063] The number of different frequency values ​​tested when repeating the determination step at the fourth time may be less than the number of different frequency values ​​tested at the third time, and / or the number of different power values ​​tested when repeating the determination step at the fourth time may be less than the number of different power values ​​tested at the third time.

[0064] The first control unit and the second control unit may be the same control unit.

[0065] The apparatus according to the second aspect may further include:

[0066] a second analog-to-digital converter (ADC), configured to convert the analog signal obtained by the second antenna into a second digital signal,

[0067] a second processing unit for processing a second digital signal,

[0068] A second digital link is used to transmit the digital signal to the second processing unit.

[0069] The second wall and / or the second analog-to-digital converter (ADC) may be movable relative to the second processing unit.

[0070] Preferably, the second analog-to-digital converter (ADC) may be placed:

[0071] a third position relative to the second processing unit, wherein the second analog-to-digital converter (ADC) is connected to the second digital link to allow the second digital signal to be transmitted to the second processing unit, and

[0072] A fourth position relative to the second processing unit, wherein the second ADC is disconnected from the second digital link to prevent the second digital signal from being transmitted to the second processing unit.

[0073] The device according to the second aspect may further comprise a second drawer comprising a second wall, 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 may rest.

[0074] The second wall may be metallic and the second antenna may be a slot antenna cut in the second wall.

[0075] A roller cabinet may comprise the apparatus for identifying or tracking tools according to the second aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] 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:

[0077] Figure 1 is a schematic diagram of a system for identifying or tracking a tool according to an embodiment of the present invention.

[0078] Figure 2 According to an embodiment of the present invention Figure 1 Schematic diagram of the slave module of the system.

[0079] Figure 3 According to an embodiment of the present invention Figure 2 The slave module perspective.

[0080] Figure 4 According to an embodiment of the present invention Figure 1 Schematic diagram of the master module 4 of the system.

[0081] Figure 5 is a side view of a roller cabinet according to an embodiment of the present invention.

[0082] Figure 6 is a perspective view of a housing of a roller cabinet according to an embodiment of the present invention.

[0083] 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

[0084] 1 / System for identifying or tracking tools

[0085] 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.

[0086] 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.

[0087] Each slave module 2 (hereinafter referred to as RF head) is connected to at least an antenna 1 via 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.

[0088] 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 .

[0089] Each power link 8 is configured to provide power to the RF head 2 .

[0090] 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 .

[0091] 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.

[0092] The interface 12 is connected via an analog link 6 at least to the antenna 1 .

[0093] 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.

[0094] The converter unit 16 is connected to the main module 4 via at least one data link.

[0095] 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 .

[0096] 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.

[0097] 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.

[0098] 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 .

[0099] 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 .

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] The processing unit 24 is connected to the data link and is configured to process the digital signal transmitted by the data link.

[0105] 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.

[0106] The tool database includes a plurality of entries, each entry including a tool identifier that may be associated with other information about the tool.

[0107] 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.

[0108] 2 / Roller cabinets including systems for identifying or tracking tools

[0109] Reference Figure 5 and 6 , a roller cabinet 32 ​​for storing tools includes the above-mentioned system for tracking or identifying tools.

[0110] 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.

[0111] The roller cabinet 32 ​​further includes wheels 38 mounted on the housing 34 for moving the roller cabinet.

[0112] like Figure 6 As shown, the housing 34 defines an interior cavity of the roller cabinet 32 ​​.

[0113] The housing 34 includes a top wall 40 , a bottom wall 42 , a rear wall 44 , and two side walls 46 , 48 .

[0114] The cavity is defined between the two side walls 46 , 48 and between the top wall 40 and the bottom wall 42 .

[0115] 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 .

[0116] 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.

[0117] The drawers 36 are stacked vertically within the cavity defined by the housing 34 .

[0118] 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.

[0119] 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 .

[0120] 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.

[0121] 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.

[0122] Tools placed in this area rest on the bottom wall 50 .

[0123] The bottom wall comprises an upper surface and a lower surface opposite to the upper surface. The bottom wall is rectangular.

[0124] 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.

[0125] 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.

[0126] 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 .

[0127] 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).

[0128] 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.

[0129] 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.

[0130] Furthermore, the RF head 2 of the system is fixed to the drawer 36 .

[0131] 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 .

[0132] Coaxial cables are prone to causing interference in radio signals. Fixing the RF head 2 to the drawer 36 is advantageous because the analog link can be short. Therefore, the potential interference caused by such an analog link 6 is limited.

[0133] 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 .

[0134] 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.

[0135] 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.

[0136] 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 .

[0137] 3 / Method for identifying or tracking a tool comprising an RFID tag

[0138] Let M be the number of predetermined tools to be secured in the roller cabinet.

[0139] Each tool can be of any type: screwdriver, hammer, pliers, etc.

[0140] 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.

[0141] 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.

[0142] 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:

[0143] A unique identifier for the tool,

[0144] The unique identifier of the drawer in which the tool is installed,

[0145] 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.

[0146] a predetermined frequency value, and

[0147] Predetermined power value.

[0148] 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.

[0149] By convention, data within entries of a database are said to be associated with each other.

[0150] To check whether any one of the M tools is present in the roller cabinet, the system performs the following steps.

[0151] 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).

[0152] 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.

[0153] For each tool fitted in the reference drawer, the processing unit performs the following sub-steps.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] Furthermore, the control unit sets the best antenna 1 to have a predetermined frequency associated with the best antenna 1 in the database.

[0158] Best antenna 1 sends a request radio signal and waits for a response signal.

[0159] 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.

[0160] 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 .

[0161] 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.

[0162] The above steps are repeated for each tool assembled in the reference drawer 36 .

[0163] 4 / Adaptive frequency and power

[0164] 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.

[0165] 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.

[0166] Furthermore, setting the system's antenna to very high power is energy consuming.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] The M tools are placed in their respective fiducial reference drawers 36, and all drawers 36 are closed.

[0171] 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:

[0172] 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.

[0173] 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.

[0174] The control unit tests different frequency values ​​and different power values ​​to determine Fij, Pij.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] The calibration step may for example be performed only once in a period of time, such as once a day or once a week.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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 metal wall (50) which delimits a first area in which a first tool including an RFID tag can be placed, a first antenna (1) for communicating with the RFID tag whenever the first tool is in the first area, The invention is characterized in that the first antenna (1) is a slot antenna cut in the first metal wall (50).

2. The device according to claim 1, further comprising a first analog-to-digital converter (16), configured to convert the analog signal acquired by the first antenna into a first digital signal, a first processing unit (14) for processing the digital signal, A digital link (10) is used to transmit the digital signal to the first processing unit (14).

3. The device according to claim 2, wherein: The first metal wall (50) and / or the first analog-to-digital converter are movable relative to the first processing unit (14).

4. The device according to claim 3, wherein: The first analog-to-digital converter is placed: a first position relative to the first processing unit, wherein the first analog-to-digital converter (16) is connected to the digital link (10) to allow the digital signal to be transmitted to the first processing unit (14), and A second position relative to the first processing unit (14), wherein the first analog-to-digital converter (16) is disconnected from the digital link (10) to prevent the digital signal from being transmitted to the first processing unit (14).

5. The device according to any one of claims 1 to 3, further comprising: A first drawer (36), the first drawer comprising the first metal wall (50), wherein the first drawer (36) is movable between a first position and a second position, the first position being a closed position of the first drawer (36) and the second position being an open position of the first drawer (36).

6. The device according to claim 5, wherein: The first metal wall (50) is a bottom wall of the first drawer (36), and the first tool can be placed on the bottom wall.

7. The device according to claim 5, wherein: The first analog-to-digital converter is secured to a back (54) of the first drawer (36).

8. The apparatus according to claim 1, further comprising a first control unit (22, 24), the first control unit being configured to set the first antenna (1) 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 a response signal transmitted by the RFID tag in response to a request signal transmitted by the first antenna (1), The first power value is the minimum power value at which the first antenna (1) can effectively detect the response signal when set at the selected frequency value, thereby extracting information about the first tool therefrom.

9. The device according to claim 8, wherein: The first control unit (22, 24) is configured to perform the following steps: determining the first frequency value and the first power value by testing different values ​​within the predetermined range of RFID frequencies and different values ​​within a power 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 response signal; and repeating this step only if the attempt fails.

10. The apparatus according to claim 9, further comprising: a second metal wall defining a second area in which a second tool including an RFID tag can be placed when the first tool is placed in the first area, A second antenna is used to communicate with the RFID tag whenever a second tool is in the second area, wherein the second antenna is a slot antenna cut in the second metal wall.

11. The apparatus according to claim 10, further comprising: a second analog-to-digital converter (16), configured to convert the analog signal acquired by the second antenna into a second digital signal, a second processing unit, configured to process the second digital signal, A second digital link is used to transmit the second digital signal to the second processing unit. 12 . The device according to claim 11 , wherein the second metal wall and / or the second analog-to-digital converter is movable relative to the second processing unit.

13. The device according to claim 12, wherein: The second analog-to-digital converter is placed at: a third position relative to the second processing unit, wherein the second analog-to-digital converter (16) 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 second processing unit, 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 device of claim 13, further comprising a second drawer, wherein: The second drawer comprises the second metal wall, which 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 analog-to-digital converter is secured to a back of the second drawer.

17. The device according to claim 10, further comprising a second control unit, The second control unit is 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 a response signal transmitted by the RFID tag of the second tool in response to a request signal transmitted by the second antenna, The second power value is a minimum value at which the second antenna can effectively detect the response signal when the second antenna is set at the selected frequency value, thereby extracting information about the second tool from the response signal.

18. The device according to claim 17, wherein: The second control unit is configured to perform the following 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 first 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 a second radio signal, and repeating the determining step only if the attempt fails.

19. A roller cabinet comprising a device for identifying or tracking a tool according to any one of the preceding claims.

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