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

Abstract

A device for identifying or tracking a tool, comprising: a first wall defining a first area in which a first tool including an RFID tag can be placed. The device includes a first antenna for communicating with the RFID tag whenever the first tool is in the first area, the communication 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. The first control unit is configured to set the first antenna to a value that meets the following criteria: (1) the first frequency is selected within a predetermined range of RFID frequencies and maximizes the power of the response signal; and (2) the first power is the minimum value such that the first antenna set with the selected first frequency value can effectively detect the response signal, so that information about the first tool can be extracted therefrom.

Description

Technical Field

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

[0002] A cabinet has been proposed that includes a system for tracking or identifying tools equipped with RFID tags. The RFID tags are passive elements (in the sense that tools equipped with RFID tags do not include any internal power source for powering the RFID tags). The system includes two antennas for communicating with the RFID tags of any tool fixed in the cabinet: a first antenna is provided at the top of the cabinet and a second antenna is provided at the bottom of the cabinet.

[0003] To check whether a tool is fixed in the cabinet, the antennas of the system transmit a request radio signal. The RFID tag of the 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 acquired by the antenna. Then, the system can extract the information to identify the tool that emitted the response.

[0004] However, when the response signal transmitted by the RFID tag of the tool and then received by the antenna is too weak, the system may not be able to detect that the tool is fixed in the cabinet.

[0005] The quality of the response signal acquired by the antenna actually depends on the settings used by the antenna that transmits 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 impede the propagation of the response radio signal. The metal walls defining the cavity in which the tool is placed can also impede this propagation.

[0007] To avoid missed detections, 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 present invention is to propose a system for tracking or identifying tools that is less affected by missed detections and does not require high energy.

[0009] Basically, a metal wall is a harsh environment vulnerable to RF interference. Defining a slot in such a metal wall to obtain a slot antenna actually converts this harsh environment into one where response signals emitted by RFID tags of tools placed in the area can be detected more effectively. This efficiency gain is achieved without increasing the power level used by the antenna. In addition, slot antennas are easier and cheaper to manufacture than standalone antennas.

[0010] 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.

[0011] To this end, a device for identifying or tracking a tool is proposed. The device includes:

[0012] A first wall that defines a first area in which a first tool including an RFID tag can be placed,

[0013] 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 emitted by the RFID tag in response to the request signal,

[0014] A first control unit configured to set a first frequency and a first power of the first antenna to values that meet the following criteria:

[0015] The first frequency is selected within a predetermined range of RFID frequencies and maximizes the power of the response signal,

[0016] The first power is the minimum power that enables the first antenna set to the selected first frequency value to effectively detect the response signal such that information about the first tool can be extracted from the response signal. This minimum value enables the first antenna to effectively detect the response signal at the minimum power when set to the selected first frequency value, so that information about the first tool can be extracted therefrom.

[0017] The device may also include the following optional features, either alone or in combination (when such a combination is technically feasible).

[0018] The first control unit may be configured to perform the following steps:

[0019] 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 a predetermined range of RFID frequencies and different values within a power range.

[0020] 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 if the attempt fails.

[0021] In addition, the number of different frequency values tested when repeating the determination step at the second time can 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 can be less than the number of different power values tested at the first time.

[0022] The apparatus may further include:

[0023] A first analog-to-digital converter (ADC) for converting the analog signal acquired by the first antenna into a first digital signal,

[0024] A first processing unit for processing the digital signal,

[0025] A digital link for transmitting the digital signal to the first processing unit.

[0026] The first wall and / or the first analog-to-digital converter (ADC) may be movable relative to the first processing unit.

[0027] Preferably, the first analog-to-digital converter (ADC) may be placed at:

[0028] 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

[0029] 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.

[0030] The apparatus may include a first drawer, the first drawer including a first wall, which is, for example, the bottom wall of the first drawer, on which the first tool may rest.

[0031] The first position may be the closed position of the first drawer, and the second position may be the open position of the drawer.

[0032] The first analog-to-digital converter (ADC) may be fixed to the first drawer, for example, fixed to the back of the drawer.

[0033] The first wall may be metallic, and the first antenna may be a slot antenna cut out in the first wall.

[0034] The apparatus may further include

[0035] A second wall that defines 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.

[0036] A second antenna for communicating with the RFID tag of the second tool whenever the second tool is in the second area.

[0037] A second control unit configured to set the second antenna to have a second frequency value and a second power value that meet the following criteria:

[0038] 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.

[0039] The second power value is the 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. This minimum value enables the second antenna set to the selected second frequency value to effectively detect the response signal with the minimum power, so that information about the second tool can be extracted therefrom.

[0040] The second control unit may be configured to perform the following steps:

[0041] 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 a predetermined range of RFID frequencies.

[0042] At a fourth time after the third time, set the second antenna to the second frequency value and the second power value determined at the third time, attempt to extract information about the second tool from the second radio signal, and repeat the determination step only if the attempt fails.

[0043] 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.

[0044] The first control unit and the second control unit may be the same control unit.

[0045] The device may further include:

[0046] A second analog-to-digital converter (ADC) for converting an analog signal obtained by the second antenna into a second digital signal.

[0047] A second processing unit for processing a second digital signal

[0048] A second digital link for transmitting the digital signal to the second processing unit

[0049] The second wall and / or the second analog-to-digital converter (ADC) may be movable relative to the second processing unit

[0050] Preferably, the second analog-to-digital converter (ADC) may be placed at

[0051] 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

[0052] 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

[0053] The device may further include a second drawer, which includes a second wall. The second drawer is different from the first drawer. The second wall is, for example, the bottom wall of the second drawer, and the second tool may be placed on the bottom wall

[0054] The second wall may be metallic, and the second antenna may be a slot antenna cut out in the second wall

[0055] A roller cabinet may include a device for identifying or tracking tools according to the present invention Description of the Drawings

[0056] Further details, features and advantages of the present invention are explained in more detail below with the help of the exemplary embodiments of the present invention shown in the drawings, in which

[0057] Figure 1 is a schematic diagram of a system for identifying or tracking tools according to an embodiment of the present invention

[0058] Figure 2 is according to an embodiment of the present invention Figure 1 a schematic diagram of a slave module of the system

[0059] Figure 3 is according to an embodiment of the present invention Figure 2 a perspective view of a slave module

[0060] Figure 4 is according to an embodiment of the present invention Figure 1Schematic diagram of the master module 4 of the system.

[0061] Figure 5 is a side view of a roller cabinet according to an embodiment of the present invention.

[0062] Figure 6 is a perspective view of the housing of a roller cabinet according to an embodiment of the present invention.

[0063] Figure 7 and 8 are two different perspective views of a drawer of a roller cabinet according to an embodiment of the present invention. Detailed implementation

[0064] 1 / System for identifying or tracking tools

[0065] Reference 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.

[0066] Each antenna 1 is configured to communicate with the 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.

[0067] Each slave module 2 (hereinafter referred to as an RF head) is connected to at least the 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.

[0068] The master module 4 is connected to each RF head 2 through at least one power link 8 and at least one data link 10.

[0069] Each power link 8 is configured to supply power to the RF head 2.

[0070] Each data link 10 is a digital link, which is configured to transmit digital signals from the RF head 2 to the master module 4 and to transmit digital signals from the master module 4 to at least one RF head 2.

[0071] Reference 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.

[0072] The interface 12 is connected to at least the antenna 1 through the analog link 6.

[0073] The power supply 14 is connected to the main module 4 via the power link 8. When the power supply unit 14 receives power via the power link 8, it supplies 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.

[0074] The converter unit 16 is connected to the main module 4 via at least one data link.

[0075] The converter unit 16 includes an analog-to-digital converter (ADC). The ADC is configured to convert the analog signals acquired by the antenna and received by the interface into digital signals, and send the digital signals to the main module 4 via the digital link 10.

[0076] The converter unit 16 may further include a digital-to-analog converter (DAC). The DAC is configured to convert the digital signals from the data link 10 into analog signals, and send the analog signals to the interface 12, such that the interface 12 can then send the analog signals to the antenna 1.

[0077] Refer to Figure 3 , the RF head 2 includes a housing 18 that houses all of the above-mentioned electronic components 12, 14, 16. These electronic components are typically included in a common circuit as Figure 3 shown.

[0078] The housing 18 may include two parts: a base 18a and a lid 18b, which may be fixed to each other to enclose the housing 18.

[0079] The housing 18 further includes a plurality of ports 20, each of which is designed to be connected to the power link 8 and the data link 10.

[0080] Now turning to Figure 4 , the main module 4 includes a power management unit 22, a processing unit 24, and means 26, 28 for accessing a tool database.

[0081] The tool database is not stored in the main module 4, but rather in the memory of a server external to 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.

[0082] Alternatively, the means for accessing the tool database includes a memory included in the main module 4, and the tool database is stored in this memory. The memory can be of any type: HDD, SSD, flash memory, etc.

[0083] The power management unit 22 is configured to supply power to the RF head 2 via the power link 8 and is configured 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 general power link 30.

[0084] The processing unit 24 is connected to the data link. It is configured to process digital signals transmitted by the data link.

[0085] Generally, the system includes 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 assign different power / frequency to different antennas 1.

[0086] The tool database includes a plurality of entries, each entry including a tool identifier that may be associated with other information about the tool.

[0087] Figure 4 All the electronic components of the main module 4 shown can generally be integrated in a common circuit of the motherboard type.

[0088] 2 / The roller cabinet including the system for identifying or tracking tools

[0089] Refer to Figure 5 and 6 , the roller cabinet 32 for storing tools includes the above system for tracking or identifying tools.

[0090] 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, seven drawers as shown in Figure 5 shown.

[0091] The roller cabinet 32 further includes wheels 38 mounted on the housing 34 for moving the roller cabinet.

[0092] As Figure 6 shown, the housing 34 defines an internal cavity of the roller cabinet 32.

[0093] The housing 34 includes a top wall 40, a bottom wall 42, a rear wall 44 and two side walls 46, 48.

[0094] The cavity is defined between the two side walls 46, 48 and is defined between the top wall 40 and the bottom wall 42.

[0095] The main module 4 is fixed to the housing. In the Figure 6 shown embodiment, the main module 4 is fixed to the inner surface of the rear wall 44.

[0096] 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.

[0097] The drawers 36 are vertically stacked in the cavity defined by the housing 34.

[0098] Each drawer 36 is movable relative to the housing 34. More precisely, each drawer 36 is arranged in the cavity and is slidable relative to the housing 34 between a closed position and an open position. In the closed position, the drawer is completely covered by the top wall 40 and is electrically connected to the links 8, 10. In the open position, the drawer 36 is separated from the rear wall 44 and the electrical connection to the links 8, 10 is also disconnected.

[0099] As Figure 7 and Figure 8 shown, the drawer 36 includes a horizontally extending bottom wall 50, and the following walls that extend vertically and are connected to the bottom wall: a front wall 52, a rear wall 54, and two side walls 56, 58.

[0100] The drawer 36 defines an area in which tools can be placed as long as the drawer 36 is in the open position. When the first drawer is in its closed position, any tool placed therein is secured in the roller cabinet 32.

[0101] This area is defined between the front wall 52 and the rear wall 54 and is defined between the two side walls 56, 58. Each of the walls 50, 52, 54, 56, 58 bounds this area.

[0102] The tools placed in this area rest on the bottom wall 50.

[0103] The bottom wall includes an upper surface and a lower surface opposite the upper surface. The bottom wall is rectangular.

[0104] At least one antenna 1 of the system is a slot antenna cut out in a metal wall that defines the area in which tools can be placed.

[0105] This arrangement is advantageous for many reasons: First, the communication between the first (slot) antenna and the RFID tags of the tools placed in the first area defined in the first drawer is particularly effective; second, there is no need to include expensive separate antennas in the system.

[0106] In Figure 7 and Figure 8 the illustrated embodiment, the metal wall in which at least one slot antenna 1 is cut out is the bottom wall 50.

[0107] The slot antenna 1 includes at least one slot opening in two opposite surfaces of a metal wall (e.g., the upper surface and the lower surface of the bottom wall).

[0108] 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 the RFID tag of the tool.

[0109] More than one slot antenna 1 can be cut out in the metal wall. In the embodiment depicted in Figure 7 and Figure 8 Eight slot antennas 1 are cut out in the bottom wall 50 of the drawer 36. The slots can extend diagonally with respect to the rear wall and the side walls.

[0110] In addition, the RF head 2 of the system is fixed to the drawer 36.

[0111] The analog link 6 that connects 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.

[0112] Coaxial cables are prone to generating interference in radio signals. It is advantageous to fix the RF head 2 to the drawer 36 because the analog link can be short. Therefore, the potential interference generated by such an analog link 6 is limited.

[0113] More precisely, the RF head 2 is fixed 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.

[0114] 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, at least one digital link 10 can be used to exchange data between the RF head 2 and the main module 4, and the main module 4 can use the power link 8 to supply power to the RF head.

[0115] 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.

[0116] According to the arrangement shown in Figure 7 and Figure 8 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, and each RF head 2 is fixed to the corresponding drawer 36.

[0117] 3 / Method for identifying or tracking tools including RFID tags

[0118] Suppose M is the number of predetermined tools to be secured in the roller cabinet.

[0119] Each tool can be of any type: screwdriver, hammer, pliers, etc.

[0120] Each tool includes an RFID tag. The RFID tag includes a memory that stores information about the tool, which includes the tool identifier. The RFID tag is capable of communicating with any antenna 1 of the system. The RFID tag is passive because it does not include any internal power source.

[0121] Each tool should be assembled in a 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 receiving one of the M tools. The shape of each cavity is complementary to the shape of one of the M tools.

[0122] In a preparatory step, the M tools are registered in the database. For each tool, a tool entry is created in the database, which includes at least:

[0123] The unique identifier of the tool,

[0124] The unique identifier of the drawer in which the tool is assembled,

[0125] The unique identifier of the best antenna 1 used to communicate with the tool when the tool is placed in the reference drawer (how to determine this best antenna 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; on the contrary, this best antenna can be part of another drawer of the roller cabinet.

[0126] A predetermined frequency value, and

[0127] A predetermined power value.

[0128] The configuration of each drawer 36 can also be registered in the database. For example, a drawer entry is created for each drawer 36, which includes: the unique identifier of the drawer, and the unique identifier of each antenna 1 included in the drawer.

[0129] By convention, the data within the entries of the database are said to be associated with each other.

[0130] To check whether any one of the M tools is present in the roller cabinet, the system performs the following steps.

[0131] The processing unit detects that the drawer has reached its closed position (this drawer is hereinafter referred to as the "reference drawer"). For example, this 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).

[0132] When the reference drawer 36 is detected to be closed, the processing unit determines all the tools assembled in the just-closed reference drawer. To this end, the processing unit accesses the database and searches for tool entries containing the unique identifier of the reference drawer 36.

[0133] For each tool assembled in the reference drawer, the processing unit performs the following sub-steps.

[0134] The processing unit determines the antenna 1 for communicating with the tool. To this end, the processing unit accesses the database and reads the unique identifier of the best antenna 1 associated with the tool in the tool entry.

[0135] As mentioned above, this best antenna 1 does not have to be part of the reference drawer itself. Therefore, the processing unit then determines the drawer 36 that includes the best antenna 1 associated with the tool. To this end, the processing unit analyzes the drawer entries registered in the database.

[0136] Then, the control unit of the main module 4 supplies the antenna 1 with an amount of electric power corresponding to the power value associated with the best antenna 1 in the database. To this end, the control unit sends electric power through the power link 8 to the RF head 2 of the drawer 36 that includes the best antenna 1. Then, this RF head 2 supplies power to the best antenna 1.

[0137] In addition, the control unit sets the best antenna 1 to have a predetermined frequency associated with the best antenna 1 in the database.

[0138] The best antenna 1 sends a request radio signal and waits for a response signal.

[0139] If the tool that the optimal antenna 1 is supposed to communicate with actually exists 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 carries information about the tool, which includes the unique identifier of the tool. Then, the optimal antenna 1 receives the response signal, converts it into an analog signal, and transmits the analog signal to the RF head 2 through the analog link 6. The ADC contained in the RF head 2 converts the analog signal into a digital signal, and then transmits the digital signal to the main module through the digital link. The processing unit extracts the unique identifier of the tool from the digital signal. Then, the processing unit accesses the database and compares the extracted unique identifier with the tool identifier associated with the optimal antenna in the database. If the two tool identifiers match, the processing unit 24 generates a message indicating that the tool exists in the roller cabinet 32, or more specifically, in the reference drawer 36.

[0140] If the optimal 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.

[0141] Any message generated by the processing unit can be sent to a user terminal including a display screen, such that the message is displayed on the display screen.

[0142] The above steps are repeated for each tool assembled in the reference drawer 36.

[0143] 4 / Adaptive frequency and power

[0144] Basically, any antenna 1 of the system can communicate with the RFID tag of a tool placed in the drawer 36 using different frequency values and different power values. The RFID tag of any tool is a passive component. The power of the response signal transmitted by the RFID tag depends on the power used by the antenna to send the request signal.

[0145] If the antenna 1 has been set to have a very low power and / or an inappropriate frequency, it may not be possible to correctly extract information from the response signal obtained from the antenna.

[0146] In addition, setting the antenna of the system to have a very high power is energy-consuming.

[0147] It should also be noted that not all RFID frequencies that the antenna 1 can be used to communicate with the RFID tag are equally effective. In fact, the power required for the antenna 1 to allow proper extraction of the information carried by the response signal depends on the frequency used by the antenna 1 to send the request signal.

[0148] In addition, multiple antennas 1 configured to use the same power and the same frequency are not equally effective for communicating with the tools placed in the drawer 36 because the antennas have different positions. An antenna 1 very close to the tool tends to communicate more effectively than another antenna far from the tool.

[0149] As described above, when the reference drawer is closed, the system attempts to communicate with each tool assembled in the reference drawer through the relevant optimal antenna 1 and the relevant power / frequency values stored in the database. These optimal antennas 1 and the power / frequency parameters they use are determined in a preliminary calibration step including the following sub-steps.

[0150] M tools are all placed in their respective reference drawers 36, and all the drawers 36 are closed.

[0151] The system determines the frequency value Fij and the 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, where the frequency value Fij and the power value Pij meet the following criteria:

[0152] The frequency value Fij is selected within a predetermined range of RFID frequencies that the antenna can use, and F maximizes the power of the response signal emitted by the RFID tag of the tool in response to the request radio signal emitted by the antenna.

[0153] 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.

[0154] The control unit tests different frequency values and different power values to determine Fij and Pij.

[0155] The control unit can, for example, set the i-th antenna to the lowest frequency of the RFID frequency range and a very low power. At this time, since the set power is too low, information cannot be extracted from the response signal obtained 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 obtained by the i-th antenna. Alternatively, the control unit can 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 obtained by the i-th antenna.

[0156] The minimum power allowing such extraction is stored in a 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 number 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.

[0157] 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 executed NM times.

[0158] At this stage, each tool j is associated with N pairs of parameters (Pij, Fij), and each pair of parameters is associated with an antenna i. Among these pairs, there is a pair including the minimum power; the antenna associated with the minimum power is selected by the system as the optimal antenna. The unique identifier of the selected optimal antenna and the values of Pij and Fij determined for the optimal antenna are written into the tool entry of the j-th tool.

[0159] The calibration step can be performed, for example, only once in a period of time, such as once a day or once a week.

[0160] Once the calibration step is completed, whenever the drawer 36 is closed, the method described in part 3 / is executed to check whether the tool is present in the roller cabinet.

[0161] If the system determines that a given tool is present in the just-closed drawer, the calibration step is not performed. This is advantageous because calibration is time-consuming.

[0162] Due to the local environment of the tool, the system may sometimes not correctly detect the tool placed back in its reference drawer. For example, due to some obstacles (such as another tool) that were not present in the reference drawer during the execution of the calibration step but are now present in the reference drawer, the optimal antenna 1 may not be able to receive the response signal sent by the tool.

[0163] To avoid such false detection, if the system determines 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 in the calibration step. However, the number of frequencies tested and / or the number of power values tested during the update step is preferably less than that during the calibration step, so that the update is shorter than the calibration step.

Claims

1. An apparatus for identifying or tracking a tool, the apparatus comprising: A first wall that defines a first region in which a first tool including an RFID tag can be placed, A first antenna for communicating with the RFID tag whenever the first tool is in the first region, the communication 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, Characterized in that a first control unit configured to set the first frequency and the first power of the first antenna to values that meet the following criteria: The first frequency is selected within a predetermined range of RFID frequencies and is such that the power of the response signal is maximized; The first power is the minimum power at which the first antenna can effectively detect the response signal when set at the selected first frequency value, so that information about the first tool can be extracted therefrom, Wherein the first control unit is configured to perform the following determination steps: At a first time when the first tool is in the first region, determine 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, and 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 and attempt to extract the information about the first tool from the response signal of the first tool; And repeat the determination step only if the attempt fails.

2. The apparatus according to claim 1, wherein The number of different frequency values tested when repeating the determination step at the second time is 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 is less than the number of different power values tested at the first time.

3. The apparatus according to claim 1, further comprising A first analog-to-digital converter (16) for converting an analog signal acquired by the first antenna into a first digital signal, A first processing unit for processing the first digital signal, A digital link for transmitting the first digital signal to the first processing unit.

4. The device according to claim 3, wherein, The first wall and / or the first analog-to-digital converter (16) is movable relative to the first processing unit.

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

6. The apparatus according to claim 5, further comprising a first drawer, the first drawer including the first wall, the first wall being the bottom wall of the first drawer, on which the first tool can rest.

7. The device according to claim 6, wherein, The first position is the closed position of the first drawer, and wherein the second position is the open position of the first drawer.

8. The apparatus according to claim 7, wherein, The first analog-to-digital converter (16) is attached to the first drawer.

9. The apparatus according to claim 8, wherein, The first analog-to-digital converter (16) is attached to the back of the first drawer.

10. The device according to claim 1, wherein The first wall is metallic, and wherein the first antenna is a slot antenna cut out in the first wall.

11. The apparatus according to any one of the preceding claims, further comprising: A second wall that defines a second region, wherein when the first tool is placed in the first region, a second tool including an RFID tag can be placed in the second region; A second antenna for communicating with the RFID tag of the second tool when the second tool is in the second region, 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 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 the minimum value at which the second antenna can effectively detect the response signal when set at the selected frequency value so that information about the second tool can be extracted from the response signal.

12. The apparatus according to claim 11, wherein, The second control unit is configured to perform the following second determination step: At a third time when the second tool is in the second region, determine the second frequency value and the second power value by testing different values and different power values within the predetermined range of RFID frequencies, 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 information about the second tool from the response signal of the second tool, and repeat the second determination step only if the attempt fails.

13. The apparatus according to claim 12, wherein, The number of different frequency values tested when repeating the second determination step at the fourth time is 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 second determination step at the fourth time is less than the number of different power values tested at the third time.

14. The apparatus according to claim 11, wherein, The first control unit and the second control unit are the same control unit.

15. The apparatus according to claim 11, further comprising A second analog-to-digital converter for converting an analog signal acquired by the second antenna into a second digital signal, A second processing unit for processing the second digital signal, A second digital link for sending the second digital signal to the second processing unit.

16. The device according to claim 15, wherein, The second wall and / or the second analog-to-digital converter is movable relative to the second processing unit.

17. The apparatus according to claim 16, wherein The second analog-to-digital converter can be placed at: 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.

18. The apparatus according to claim 11, further comprising a second drawer, the second drawer including the second wall, wherein, The second drawer is different from the first drawer, the second wall is the bottom wall of the second drawer, and the second tool can be placed on the bottom wall.

19. The apparatus according to claim 11, wherein The second wall is metallic, and wherein the second antenna is a slot antenna cut out in the second wall.

20. A roller cabinet comprising means for identifying or tracking tools according to any one of the preceding claims.

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