Automatic calibration UWB module for vehicle access system

Abstract

The invention relates to at least two UWB modules (1101; 1102, 1102; 1103, 1103; 1104), wherein each UWB module comprises a respective transceiver unit, a respective timestamp unit, and a respective signal processing unit. Each UWB module can calculate a current distance value between the UWB module and the badge. Each UWB module is also able to calculate the value of the calibrated distance by means of bidirectional communication with the other UWB module, the calculation of the time of flight and the calculation of the difference between the measured distance and the actual distance between the two UWB modules.

Description

Technical Field

[0001] The present invention relates to the field of vehicle entry systems.

[0002] The vehicle entry system is installed in a motor vehicle and is able to exchange information with at least one badge carried by a user wishing to enter the vehicle in order to be able to authenticate and locate the user. Background Art

[0003] In a manner known per se, a vehicle entry system conventionally comprises:

[0004] - Central computer;

[0005] a long-range transceiver, which is advantageously based on the so-called BLE (“Bluetooth Low Energy” for English) technology and which cooperates with a central computer for remotely registering and authenticating the user-bearer of the badge authorized to access the vehicle;

[0006] - medium-range transceiver means, advantageously based on the so-called UWB (for “Ultra-Wide Band” in English) technology and which cooperate with a central computer for locating an authenticated user and, depending on the user's position, for operating certain functions of the vehicle at a certain time (for example, operating the lighting of the vehicle upon entering a first perimeter and then operating the unlocking of the doors upon entering a second perimeter narrower than the first); and

[0007] - Where appropriate, a short-range presence detection device which is able to detect the close proximity of an authenticated user and which cooperates with the central computer for operating at least the function of unlocking the doors of the vehicle.

[0008] Throughout this document, the term UWB (for "ultra-wide band" in English) refers to radio frequency signals of low energy and large spectrum width. In particular, UWB radio frequency signals are defined by a ratio of bandwidth divided by center frequency greater than or equal to 20%, or by a bandwidth of 250 MHz or more.

[0009] The medium-range transceiver device comprises in particular a set of UWB modules, each UWB module being adapted to be positioned at a predetermined position on the vehicle during use.

[0010] Each UWB module preferably includes:

[0011] - a transceiver unit configured to: send a badge query UWB signal, and in response receive a badge response UWB signal;

[0012] - A timestamp unit, configured to: store timestamp data related to the moment of sending a badge query signal and the moment of receiving a badge response signal; and

[0013] - A signal processing unit, configured to: calculate a current distance value between the UWB module and the badge by means of the timestamp data.

[0014] In a manner known per se, each badge response signal further contains timestamp data stored in the badge. This allows the signal processing unit to accurately determine the propagation time of the radio frequency signal between the UWB module and the badge even if the clocks of the badge and the UWB module are not exactly synchronized.

[0015] In any case, the signal processing unit is configured to: determine the propagation time of the radio frequency signal between the UWB module and the badge, which is called the time of flight. This time of flight allows the determination of the current distance value between the UWB module and the badge, and these two quantities are related by the speed of light in a vacuum or more particularly the speed of radio waves in air.

[0016] In particular, there is:

[0017] d mes = c * Δt + d cal where

[0018] d mes : The current distance value between the UWB module and the badge;

[0019] c: The speed of light in a vacuum;

[0020] Δt: The time of flight; and

[0021] d cal : A calibration distance specific to the UWB module and particularly related to the slight delay introduced by the UWB module itself.

[0022] In a known manner, the calibration distance d cal is calculated in the factory before the UWB module is installed in the vehicle and is stored in the memory within the UWB module. In use, the calibration distance d cal is used by the signal processing unit to calculate the current distance value between the UWB module and the badge.

[0023] In use, each in the UWB module determines the current distance value from the badge. These multiple distance values are transmitted to a central computer, which calculates and determines the position of the badge by triangulation.

[0024] An object of the present invention is to propose a solution to improve the accuracy of determining the position of the badge. Summary of the Invention

[0025] This object is achieved by means of a set of at least two (preferably at least three) modules called UWB modules, each of which includes a respective transceiver unit, a respective timestamp unit, and a respective signal processing unit, and in each UWB module:

[0026] - The transceiver unit is configured to: transmit and receive radio frequency signals of the ultra-wideband type, in particular to transmit a tag query signal and to receive in response a tag response signal from the tag;

[0027] - The timestamp unit is configured to: store first timestamp data related to the moment of transmission of the tag query signal and the moment of reception of the tag response signal; and

[0028] - The signal processing unit is configured to: use the first timestamp data to calculate a current value of the first time of flight corresponding to the propagation duration of the radio frequency signal between the UWB module and the tag, and then to calculate a current distance value between the UWB module and the tag;

[0029] According to the invention, in each UWB module:

[0030] - The transceiver unit is further configured to: transmit a UWB module query signal destined for at least one of the other three UWB modules, and to receive in response at least one UWB module response signal (from at least one of the other three UWB modules);

[0031] - The timestamp unit is configured to: store second timestamp data related to the moment of transmission of the UWB module query signal and the moment of reception of the UWB module response signal;

[0032] - The signal processing unit is configured to: use the second timestamp data to calculate at least one current value of the second time of flight, each of which corresponds to the propagation duration of the radio frequency signal between the UWB module and a respective one of the other three UWB modules, and then to obtain therefrom a current distance value between the UWB module and the other UWB modules, called the measured spacing;

[0033] - The signal processing unit includes a memory that stores at least one actual spacing value, each of which corresponds to an actual distance value between the UWB module and a respective one of the other three UWB modules; and

[0034] - The signal processing unit is configured to: calculate a calibrated distance value by means of at least one measured spacing and at least one actual spacing value.

[0035] In other words, each UWB module is capable of:

[0036] - Calculate a current distance value between the UWB module and the badge by means of two-way communication with the badge; and

[0037] - Calculate a calibration distance value by means of two-way communication with another UWB module, calculation of the time of flight, and calculation of the difference between the measured distance and the actual distance between the two UWB modules.

[0038] Thus, each UWB module can be automatically calibrated, i.e., it calculates by itself the value of the calibration distance associated with the distance calculation it implements.

[0039] The automatic calibration according to the invention does not impose specific conditions, such as the link to an external calibration device during maintenance operations. In other words, the automatic calibration according to the invention can be repeated as many times as desired over time. Thus, their respective calibration distances can be updated throughout the lifespan of the UWB modules. Thus, the possible drift of the calibration distance associated with the UWB module can be taken into account in the distance calculation provided by each UWB module. The drift may be due to the effects of aging and wear of materials, slight offsets in the physical positions of the module components, etc.

[0040] At each moment, the calibration distance used to calculate the distance by means of the UWB module is thus very close to the actual value of the calibration distance. The error in the distance calculation is thus minimized, and thus the error in the determination of the badge position is minimized.

[0041] The invention thus provides a solution for improving the accuracy of the determination of the position of a badge in a system for determining the position of a badge by means of distance measurements provided by each of a set of UWB modules according to the invention.

[0042] The automatic calibration uses at least one other UWB module present in the UWB modules on the vehicle, each of these UWB modules being deployed in a fixed and known position on the vehicle. Thus, the automatic calibration does not impose the addition of dedicated additional elements. The compactness as well as the manufacturing cost are thus optimized.

[0043] Finally, the automatic calibration is implemented by each UWB module in a completely autonomous manner. In particular, compared to the prior art, the automatic calibration does not require any additional data exchange between the UWB module and the central computer. The invention can thus be implemented by means of the same central computer as the prior art without any adaptation.

[0044] In particular, each UWB module can actively perform the automatic calibration by itself at a predetermined moment (for example, each time it transitions from the standby mode to the active mode).

[0045] Two UWB modules can exchange multiple UWB module query signals and multiple UWB module response signals. In a complementary manner or as a variant, the reception of a wake-up signal from a UWB module with which two-way communication is subsequently established can occur before the transmission of the query signal.

[0046] Preferably, each UWB module response signal contains so-called additional timestamp data, which is stored and then included in the signal in the UWB module that transmits the response signal. Each UWB module can then:

[0047] - extract this additional timestamp data from the response signal it receives, and

[0048] - also use this additional timestamp data to calculate a current value of the second time of flight.

[0049] The additional timestamp data is advantageously related to the time interval between the reception of the UWB module query signal and the transmission of the UWB module response signal for the reply within the same UWB module. It is thus possible to accurately determine the propagation time between them even if the respective clocks of the two UWB modules are not exactly synchronized.

[0050] Preferably, in each UWB module, the signal processing unit is configured to: calculate the value of the calibrated distance by means of the difference between the measured distance and the actual distance value.

[0051] In an advantageous manner, in each UWB module:

[0052] - the memory stores a plurality of actual distance values, which respectively correspond to the actual distance values between the UWB module and each of the other UWB modules;

[0053] - the UWB module is configured to: calculate a plurality of measured distances, which respectively correspond to the corresponding values of the distances between the UWB module and each of the other UWB modules; and

[0054] - the UWB module is configured to: calculate the value of the calibrated distance by means of the respective differences between the measured distances and the corresponding actual distance values and combine the differences.

[0055] In each UWB module, the signal processing unit is configured to: store the value of the calibrated distance and use the value of the calibrated distance when calculating the current distance value between the UWB module and the badge later.

[0056] In each UWB module, the signal processing unit can be configured to:

[0057] - Determine an initial value of the calibration distance, and then use the initial value of the calibration distance as the value of the calibration distance when calculating the current distance value between the UWB module and the badge thereafter; then

[0058] - Determine the value of at least one updated calibration distance, and then use the value of at least one updated calibration distance as the value of the calibration distance when calculating the current distance value between the UWB module and the badge thereafter.

[0059] Advantageously, each UWB module has: a so-called conventional operating mode in which it is configured to provide at least one current distance value relative to the badge; and a so-called automatic calibration operating mode in which it is configured to provide the value of the calibration distance. Each UWB module further includes a control unit configured to control the UWB module to switch to the automatic calibration mode.

[0060] In an advantageous manner, in each UWB module, the signal processing unit is configured to: compare the value of the calibration distance with a predetermined threshold, and generate an alarm signal when the value of the calibration distance is greater than the threshold.

[0061] In each UWB module, the signal processing unit may be configured to:

[0062] - Detect a faulty module among the set of UWB modules by comparing the absolute difference between the measured spacing and the corresponding actual spacing value with a predetermined threshold; and

[0063] - When the presence of a faulty module among the set of UWB modules has been detected, control the UWB module identified as faulty to be deactivated.

[0064] The present invention also encompasses a system for locating a user, which is intended to be integrated into a motor vehicle and includes a set according to the present invention. The system further includes a central computer connected to each of the UWB modules in the set and configured to:

[0065] - Receive the current distance value between the UWB module and the badge from each respective UWB module among the UWB modules; and

[0066] - Calculate the current position of the badge relative to the vehicle by means of the current distance value.

[0067] Preferably, the central computer is further configured to: control the locking and / or unlocking of at least one door of the motor vehicle especially according to at least one current position of the badge relative to the vehicle.

[0068] The system according to the invention may further include a badge, the badge being intended to be carried by a user wishing to enter a motor vehicle, and the badge including a memory that stores an authentication code.

[0069] The invention also relates to a vehicle, the vehicle including the assembly according to the invention.

[0070] The invention also relates to a method implemented in each UWB module of the assembly according to the invention, the method comprising the following steps:

[0071] a / Sending a UWB module query signal to at least one of the other three UWB modules and receiving at least one UWB module response signal in response;

[0072] b / Storing second timestamp data related to the moment of sending of the UWB module query signal and the moment of receiving of the UWB module response signal;

[0073] c / Calculating, by means of the second timestamp data, a current value of a second time of flight corresponding to the propagation duration of a radio frequency signal between the UWB module and a corresponding one of the other three UWB modules, and using the current value of the second time of flight to calculate a corresponding measured distance;

[0074] d / Calculating the difference between the measured distance and the corresponding actual distance value to obtain a calibrated distance value; and then

[0075] e / Using the calibrated distance value to subsequently calculate at least one current distance value between the UWB module and the badge.

[0076] Advantageously, steps a / to d / are implemented a plurality of times during the lifetime of the assembly according to the invention, and each time step e / is implemented using the last calculated calibrated distance value.

[0077] The method according to the invention may further include the following steps:

[0078] - Detecting a faulty module among the UWB modules of the assembly by comparing the absolute distance difference between the measured distance and the corresponding actual distance value with a predetermined threshold; and

[0079] - When the presence of a faulty module among the UWB modules of the assembly has been detected, operating the UWB module identified as faulty to a disabled state. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Other features and advantages of the invention will become more apparent on reading the following description. The description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:

[0081] ​Figure 1 Figure 1 illustrates in a schematic way the assembly and system according to the invention integrated into a motor vehicle;

[0082] Figure 2 Figure 2 illustrates in a schematic way Figure 1 the assembly, and illustrates the two-way communication with the presence of other UWB modules of the assembly for one of the UWB modules of the assembly;

[0083] Figure 3 Figure 3 illustrates in a schematic way the UWB modules in the assembly according to the invention; and

[0084] Figure 4 Figure 4 illustrates in a schematic way the method implemented within the UWB modules in the assembly according to the invention. DETAILED DESCRIPTION

[0085] First, refer to Figure 1 and describe the assembly 100 according to the invention in a schematic way.

[0086] The assembly 100 consists of a plurality of UWB modules or anchors, and here four UWB modules are labeled 1101, 1102, 1103, and 1104.

[0087] In use, the four UWB modules are integrated into the motor vehicle 10 shown in dashed lines and in a top view. The four UWB modules are more particularly deployed at the four corners of the motor vehicle 10 (the four corners are in the representation of the vehicle defined in the top view). Figure 1 The four UWB modules are further described in more detail below.

[0088] Each of the four UWB modules will be described in more detail below.

[0089] Figure 1 Also illustrated are: a central computer 200, which is loaded in the motor vehicle 10; and a badge 300, which is intended to be carried by a user who wishes to enter the interior of the motor vehicle 10.

[0090] In use, each of the four UWB modules 1101, 1102, 1103, and 1104 can exchange radio frequency signals of the UWB type with the badge 300. The two-way communication between the badge 300 and each of the corresponding UWB modules 1101, 1102, 1103, and 1104 is characterized by corresponding arrows 1011, 1012, 1013, and 1014 in Figure 1 .

[0091] ​​​​​​​This signal exchange allows each UWB module to determine its distance from the badge 300 by calculating the time of flight. Each of the UWB modules transmits this distance to the central computer 200, and the central computer 200 determines the position of the badge 300 relative to the vehicle 10 by triangulation. The UWB modules 1101, 1102, 1103, and 1104 thus form a positioning system with the computer 200. Optionally, the positioning system can be defined as also including the badge 300.

[0092] The badge 300 can be a dedicated device or can be formed by a smartphone equipped with a dedicated application. In any case, the badge 300 is configured to receive, process, and transmit UWB radio frequency signals, allowing the UWB modules to calculate the time of flight to the said badge.

[0093] Advantageously, the badge 300 also includes a memory that stores an authentication code that can be recognized at the central computer 200.

[0094] Advantageously, the badge 300 is also configured to transmit and receive radio frequency signals using a technology different from UWB, especially the long-range radio frequency transmission BLE technology. This long-range transmission can be used for the exchange of data related to the authentication code mentioned above.

[0095] The central computer 200 is installed in the vehicle 10. It includes elements such as at least one processor associated with one or more memories. It is configured to: exchange data with at least each of the four UWB modules 1101, 1102, 1103, and 1104.

[0096] The central computer 200 can have many functions other than just locating the badge 300. For example, it can be configured to manipulate the locking and / or unlocking of at least one door of the motor vehicle 10 especially based on at least one current position of the badge 300 and the authentication code transmitted by the badge 300. In other words, the central computer 200 and the four UWB modules 1101, 1102, 1103, and 1104 then belong to a vehicle access system, preferably a passive type system.

[0097] According to the present invention, and as illustrated in Figure 2 each of the four UWB modules 1101, 1102, 1103, and 1104 is also capable of exchanging UWB-type radio frequency signals with each of the other three UWB modules. In particular:

[0098] - The first UWB module 1101 is capable of exchanging UWB signals with each of the three UWB modules 1102, 1103, and 1104;

[0099] - The second UWB module 1102 is capable of exchanging UWB signals with each of the three UWB modules 1101, 1103, and 1104;

[0100] - The third UWB module 1103 is capable of exchanging UWB signals with each of the three UWB modules 1102, 1101, and 1104; and

[0101] - The fourth UWB module 1104 is capable of exchanging UWB signals with each of the three UWB modules 1102, 1103, and 1101.

[0102] In Figure 2 a two-way communication between the second UWB module 1102 and each of the three UWB modules 1101, 1103, and 1104 is represented by means of three arrows 1021, 1023, 1024.

[0103] Figure 3 Thus, the UWB modules 110 of the set 100 according to the invention are illustrated in a schematic manner i＝1,2,3或4 .

[0104] Each UWB module 110 of the set 100 according to the invention i＝1,2,3或4 comprises:

[0105] - a transceiver unit 111 i＝1,2,3或4 ;

[0106] - a timestamp unit 112 i＝1,2,3或4 ; and

[0107] - a signal processing unit 113 i＝1,2,3或4 .

[0108] The transceiver unit 111 i＝1,2,3或4 is configured to transmit and receive radio frequency signals of the UWB type. To this end, it comprises in particular: an electronic oscillator; and at least one radio frequency antenna capable of converting an electrical signal into a radio frequency signal and vice versa.

[0109] Here, the transceiver unit 111 i＝1,2,3或4 is more particularly configured to:

[0110] - send at least one badge query signal destined for a badge such as Figure 1 the badge 300;

[0111] - receive at least one badge response signal from the badge that has received the badge query signal in use;

[0112] - send at least one UWB module query signal, which is marked as SE(i) in Figure 3 where i relates to the transmitter UWB module; and

[0113] - Receive at least one UWB module response signal, which is labeled as SR(i,j) in Figure 3 where i relates to the UWB module that sends the query signal, and j relates to the UWB module that sends the response signal.

[0114] In other words, in addition to their ability to exchange signals with the badge, the UWB modules of the set according to the invention are also connected in a network.

[0115] The badge query signal and the badge response signal are not shown in Figure 3 and correspond to the UWB signals sent by the UWB modules of the prior art.

[0116] The UWB module query signal is a UWB radio frequency signal. It can be transmitted in turn in the direction towards each of the other three UWB modules. As a variant, the UWB module query signal is transmitted simultaneously in multiple directions in space so as to be received by each of the other three UWB modules.

[0117] The UWB module query signal can have characteristics similar to those of the badge query signal, except that:

[0118] - When the badge query signal is sent, the other UWB modules are placed in a mode where they do not respond to the reception of such a signal, while

[0119] - When the UWB module query signal is sent, the other UWB modules are placed in a mode where they respond to the reception of such a signal.

[0120] The UWB module response signal is a UWB radio frequency signal. It can be similar to the badge response signal. The UWB module response signal is sent by the other UWB modules in the set of UWB modules according to the invention when they receive the UWB module query signal.

[0121] Therefore, in each UWB module, the transceiver unit 111 i＝1,2,3或4 is capable of:

[0122] - Receive at least one UWB module response signal from the other UWB modules in the set of UWB modules, and also

[0123] - Send such a UWB module response signal when receiving the UWB module query signal from the other UWB modules in the set of UWB modules.

[0124] In other words, in each UWB module, the transceiver unit 111 i＝1,2,3或4It can achieve two-way communication with another UWB module. This two-way communication requires at least the exchange of a query signal and a response signal. There may also be a wake-up signal, which is transmitted from one UWB module to another UWB module for establishing two-way communication.

[0125] In fact, the transceiver unit 111 i＝1,2,3或4 can receive UWB module response signals from each of the other three UWB modules in the set, either simultaneously or non-simultaneously.

[0126] The timestamp unit 112 i＝1,2,3或4 is connected to the transceiver unit 111 i＝1,2,3或4 . It is configured to store:

[0127] - First timestamp data, which is related to the moment of sending the badge query signal and the moment of receiving the badge response signal (as in the UWB module of the prior art); and

[0128] - Second timestamp data, which is related to the moment of sending the UWB module query signal (labeled as SE(i)) and the moment of receiving the UWB module response signal (labeled as SR(i,j)) that is sent by another UWB module in the UWB module in response to receiving the signal SE(i).

[0129] The second timestamp data can be related to the corresponding moments of receiving UWB module response signals from each of the other three UWB modules.

[0130] The timestamp unit 112 i＝1,2,3或4 can include its own memory, in which the timestamp data is stored. As a variant, it writes the data directly into the signal processing unit 113 i＝1,2,3或4 .

[0131] In any case, the signal processing unit 113 i＝1,2,3或4 is connected to the timestamp unit 112 i＝1,2,3或4 so as to be able to receive the first timestamp data and the second timestamp data.

[0132] In an advantageous manner, at least part of the second timestamp data can be encoded or included in the UWB module response signal sent by the module.

[0133] The signal processing unit 113 i＝1,2,3或4 is configured to be able to perform first signal processing and second signal processing. It advantageously includes at least one microcontroller.

[0134] In an advantageous embodiment, the transceiver unit 111 i＝1,2,3或4 , the timestamp unit 112 i＝1,2,3或4and the signal processing unit 113 i＝1,2,3或4 are integrated together in the same printed circuit. This thus eliminates the connection cables between these components that could introduce additional delays.

[0135] The first signal processing is similar to the signal processing existing in the prior art. It consists in:

[0136] - using first timestamp data to calculate a current value of the first time of flight between the UWB module 110 i and a badge (such as Figure 1 badge 400), the current value of the first time of flight corresponding to the propagation duration of the radio frequency signal between the UWB module 110 i and the badge; and then

[0137] - calculating, by means of said time of flight, a current distance value between the UWB module 110 i and the badge.

[0138] Advantageously, the calculation of the current value of the first time of flight also uses additional timestamp data extracted from the badge response signal. These data are preferably related to the time interval between signal reception and signal transmission at the badge.

[0139] In a manner known per se, the current distance value is given by the following formula:

[0140] d B (t) = Δt1(t) * c + d cal , where

[0141] d B (t): the value of the distance between the UWB module 110 i and the badge at time t;

[0142] c: the speed of light in a vacuum;

[0143] Δt1(t): the value of the first time of flight at time t; and

[0144] d cal : a predetermined calibration distance associated with the UWB module 110 i .

[0145] The calibration distance d cal is specific to the UWB module 110 i under consideration. It generally takes a non-zero value, especially because of the various time delays that may be introduced within the UWB module.

[0146] The second signal processing is original. It consists in:

[0147] - using second timestamp data to calculate the UWB module 110i at least one current value of a second time of flight between it and one of the other three UWB modules. Each current value of the second time of flight corresponds to the propagation duration of a radio frequency signal between the UWB module 110 i and one of the other three UWB modules; then

[0148] - calculating, by means of at least one time of flight, at least one current distance value between the UWB module 110 i and one of the other three UWB modules. Each current distance value is referred to as a measured spacing.

[0149] Advantageously, the calculation of the current value of the second time of flight also uses additional timestamp data extracted from the UWB module response signal. These additional timestamp data are preferably related to the time interval between the reception of the query signal and the transmission of the response signal at the UWB module transmitting the response signal. For this purpose, each UWB module is configured to: both include such data in the UWB module response signal it transmits and extract such data from the UWB module response signal it receives.

[0150] The second signal processing may include: calculating a plurality of current values of the second time of flight between the UWB module 110 i and each of the other three UWB modules accordingly. It may then include: calculating a plurality of current distance values between the UWB module 110 i and each of the other three UWB modules accordingly.

[0151] The signal processing unit 113 i＝1,2,3或4 includes a memory ( Figure 3 not specifically shown in the figure), and the memory stores at least one actual spacing value. Each actual spacing value corresponds to an actual distance value between the UWB module 110 i and a corresponding one of the other three UWB modules. Under the conditions of use, these actual spacing values are known data related to the physical positions of the UWB modules. It actually relates to the actual distances between them when the UWB modules are installed on a motor vehicle. The actual spacing values may be standard data common to all vehicles of the same model. As a variant, a preliminary step may be provided: in particular, measuring the actual spacing values on the motor vehicle and storing the measurements in the signal processing unit 113 i＝1,2,3或4 of the vehicle.

[0152] The signal processing unit 113 i＝1,2,3或4 is further configured to: calculate a calibrated distance d cal by means of at least one measured spacing and at least one actual spacing value.

[0153] Calibration distance d cal The value of is in particular based on at least one difference δ j , for example:

[0154] δ j = E R (j) - Δt2(t; j)*c, where

[0155] E R (j): The actual spacing from another UWB module with index j;

[0156] c: The speed of light in a vacuum; and

[0157] Δt2(t; j): The second time-of-flight value obtained at time t and by means of the signal from the UWB module with index j, where Δt2(t; j)*c corresponds to the actual spacing value between the UWB module 110 i and the UWB module 110 j and the actual spacing value between the UWB module 110

[0158] Calibration distance d cal The value of is obtained, for example, for each of three other UWB modules 110 j and, where appropriate, for each measurement time, as the arithmetic mean of the δ j values. The mean value can be weighted, for example, to give a greater weight to the actual spacings that are least susceptible to errors, etc.

[0159] In fact, each UWB module 110 i＝1,2,3或4 advantageously has two operating modes (in addition to the standby mode):

[0160] - A mode called the "conventional" mode, in which it is configured to provide at least one current distance value relative to the badge; and

[0161] - A mode called the "automatic calibration" mode, in which it is configured to provide the value of the calibration distance.

[0162] Preferably, each UWB module 110 i＝1,2,3或4 is able to initiate a switch to the automatic calibration mode by itself. In particular, each UWB module 110 i＝1,2,3或4 is able to initiate communication with another UWB module by itself, followed by subsequent steps that allow the value of the calibration distance d cal to be finally determined. In other words, each UWB module 110 i＝1,2,3或4 is able to initiate the implementation of the steps of the method according to the invention, as described below with reference to Figure 4 Each UWB module 110 i＝1,2,3或4be able to perform this switch actively on its own, without an external request, in particular via a central computer or an external calibration device or a smartphone.

[0163] To perform this switch, each UWB module 110 i＝1,2,3或4 advantageously includes a corresponding manipulation unit 114 i＝1,2,3或4 . Each manipulation unit 114 i＝1,2,3或4 is configured to initiate the implementation of the steps of the method according to the invention at a predetermined moment, for example each time the motor vehicle is started.

[0164] In each UWB module, the manipulation unit is thus configured to manipulate the implementation of the following steps at a predetermined moment:

[0165] - sending at least one UWB module query signal via the transceiver unit and receiving at least one UWB module response signal;

[0166] - storing corresponding second timestamp data by means of the timestamp unit;

[0167] - calculating at least one current value of the second time of flight by means of the signal processing unit, then calculating at least one corresponding measured distance, and finally calculating the value of the calibrated distance.

[0168] Next, reference is made to Figure 4 the steps of the method according to the invention implemented at each UWB module 110 i of the set according to the invention.

[0169] In the first step 401, a UWB module query signal as described above is sent. This step 401 is implemented by means of the transceiver unit 111 i＝1,2,3或4 .

[0170] In the second step 402, at least one UWB module response signal as described above is received. This step 402 is implemented by means of the transceiver unit 111 i＝1,2,3或4 .

[0171] These steps 401 and 402 can be repeated multiple times.

[0172] In the third step 403, the second timestamp data as described above related to the moment of sending the signal in step 401 and the moment of receiving the signal in step 402 is stored. This step 403 is implemented by means of the timestamp unit 112 i＝1,2,3或4 . It can be implemented simultaneously with steps 401 and 402. In Figure 4 , the second timestamp data is labeled as Ti.

[0173] In the fourth step 404, at least one current value of the second time of flight is calculated as described previously. This step 404 is implemented by means of the signal processing unit 113 i＝1,2,3或4 In Figure 4 , at least one time of flight value thus calculated is labeled as Δt.

[0174] In the fifth step 405, at least one measurement spacing as described previously is calculated. This step 405 is implemented by means of the signal processing unit 113 i＝1,2,3或4 In Figure 4 , at least one measurement spacing thus calculated is labeled as E m .

[0175] In the sixth step 406, the difference between at least one measurement spacing E m and the corresponding actual spacing value E r is calculated, and the value of the calibration distance as described previously is obtained therefrom. This step 406 is implemented by means of the signal processing unit 113 i＝1,2,3或4 In Figure 4 , the value of the calibration distance is labeled as d cal .

[0176] The method then includes a step (not shown) of updating the value of a constant.

[0177] The value d cal is then used to update the value of the constant stored in the signal processing unit 113 i＝1,2,3或4 , and is used as the calibration distance for calculating the current distance value between the UWB module 110 i and the badge. Thus, subsequent calculations of the distance to the badge will be based on the value of the calibration distance calculated by means of the previous steps 401 to 406.

[0178] Advantageously, during the lifetime of each UWB module, new values of the calibration distance can be calculated multiple times. Each time the new value of the calibration distance is used to update the value of the said constant. Thus, the influence of the aging of each module over time is taken into account.

[0179] The present invention is not limited to the examples described previously and also includes many other variants, for example in the case of a different number of UWB modules in a set of modules. For example, the set may include only two UWB modules, each UWB module being installed on a respective B-pillar of a vehicle in use. According to another variant, the set may include more than four UWB modules, where in use, one UWB module is at each corner of the vehicle, and one or more UWB modules are at the center of the vehicle or on the B-pillars.

[0180] It can be noted that a large increase in the calibration distance can indicate a malfunction of at least one of the UWB modules. In an advantageous variant, in each UWB module, the signal processing unit is configured to:

[0181] - Detect a faulty module among the set of UWB modules by comparing the absolute spacing difference between the measured spacing and the corresponding actual distance value with a predetermined threshold; and

[0182] - When the presence of a faulty module among the set of UWB modules has been detected, manipulate the UWB module identified as faulty to be deactivated.

[0183] In fact, the UWB module can manipulate its own deactivation or the deactivation of a third-party module.

[0184] For example, the UWB module labeled A calculates the measured spacing E relative to the second UWB module labeled B AB and correspondingly calculates the measured spacing E relative to the third UWB module labeled C AC .

[0185] If E AB is very far from the actual distance value between modules A and B (exceeding the first predetermined threshold), while E AC is quite close to the actual distance value between modules A and C (below a second predetermined threshold that is different from or the same as the first predetermined threshold), then module B is considered faulty, and module A manipulates module B to be deactivated.

[0186] If E AB is very far from the actual distance value between modules A and B (exceeding the first predetermined threshold), and E AC is also very far from the actual distance value between modules A and C (exceeding a second predetermined threshold that is different from or the same as the first predetermined threshold), then module A itself can be considered faulty and module A deactivates itself.

[0187] The deactivation of the UWB module is advantageously accompanied by the sending of an alarm signal, which is intended to inform the user of the vehicle that maintenance is required.

Claims

1. A set (100) of at least two modules, called UWB modules (1101; 1102; 1103; 1104; 110 i ), for a user positioning system intended to be integrated into a motor vehicle, wherein each UWB module is intended to be positioned in a predetermined position on the motor vehicle in use and comprises a respective transceiver unit (111 i ), a respective timestamp unit (112 i ) and a respective signal processing unit (113 i ), and in each UWB module: - The transceiver unit (111 i ) is configured to: transmit and receive radio frequency signals of the ultra-wideband type, in particular to transmit a tag query signal and to receive in response a tag response signal from a tag (300); - The timestamp unit (112 i ) is configured to: store first timestamp data related to the time of transmission of the logo query signal and the time of reception of the logo response signal; and - The signal processing unit (113 i ) is configured to: use the first timestamp data to calculate a first current value of the time of flight corresponding to the propagation duration of the radio frequency signal between the UWB module and the badge (300), and then calculate a current distance value between the UWB module and the badge (300); It is characterized in that In each UWB module (1101; 1102; 1103; 1104; 110 i ) there is: - The transceiver unit (111 i ) is further configured to: send a UWB module query signal (SE(i)) to at least one of the other three UWB modules as a destination, and receive at least one UWB module response signal (SR(i,j)) for the response; - The timestamp unit (112 i ) is configured to store second timestamp data (Ti) related to the time of transmission of the UWB module query signal (SE(i)) and the time of reception of the UWB module response signal (SR(i,j)); - The signal processing unit (113 i ) is configured to: use the second timestamp data to calculate at least one current value of the second time of flight (Δt), each corresponding to the propagation duration of a radio frequency signal between the UWB module and a respective one of the other three UWB modules, and then obtain therefrom at least one current distance value between the UWB module and the other UWB module, referred to as the measured spacing (E m ); - The signal processing unit (113 i ) includes a memory that stores at least one actual spacing value (E r ), each of which corresponds to an actual distance value between the UWB module and a corresponding one of the other three UWB modules; and - The signal processing unit (113 i ) is configured to: calculate the value of the calibration distance (d m ) by means of the at least one measurement spacing (E r ) and the at least one actual spacing value (E cal ).

2. The set (100) according to claim 1, characterized in that, In each UWB module (1101; 1102; 1103; 1104; 110 i ), the signal processing unit (113 i ) is configured to: calculate the value of the calibration distance (d m ) by means of the difference between the measured spacing (E r ) and the actual spacing value (E cal ).

3. The set (100) according to claim 1 or 2, characterized in that, In each UWB module (1101; 1102; 1103; 1104; 110 i ): - the memory stores a plurality of actual spacing values, each of the plurality of actual spacing values corresponding to an actual spacing value between the UWB module and each of the other UWB modules; - the UWB module is configured to: calculate a plurality of measured spacings, the plurality of measured spacings corresponding to respective values of distances between the UWB module and each of the other UWB modules; and - the UWB module is configured to: calculate a calibrated distance value by means of a respective difference between a measured spacing and a corresponding actual spacing value and combining the differences.

4. The set (100) according to any one of claims 1 to 3, characterized in that, In each UWB module (1101; 1102; 1103; 1104; 110 i ), the signal processing unit (113 i ) is configured to: save the value of the calibrated distance (d cal ), and use the value of the calibrated distance (d cal ) when calculating the current distance value between the UWB module and the badge (300) thereafter.

5. The set (100) according to claim 4, characterized in that, In each UWB module (1101; 1102; 1103; 1104; 110 i ) the signal processing unit (113 i ) is configured to: - Determine an initial value of the calibrated distance, and then use the initial value of the calibrated distance as the value of the calibrated distance when calculating a current distance value between the UWB module and the badge (300) thereafter; then - Determine at least one updated calibrated distance value, and then use the at least one updated calibrated distance value as the value of the calibrated distance when calculating a current distance value between the UWB module and the badge (300) thereafter.

6. The set (100) according to any one of claims 1 to 5, characterized in that, Each UWB module (1101; 1102; 1103; 1104; 110 i ) has: a so-called traditional operating mode, in which it is configured to provide at least one current distance value relative to the badge (300); and a so-called automatic calibration operating mode, in which it is configured to provide a calibrated distance (d cal ) value. Each UWB module also includes a manipulation unit (114 i ), and the manipulation unit (114 i ) is configured to manipulate the switching of the UWB module to the automatic calibration mode.

7. The set (100) according to any one of claims 1 to 6, characterized in that, In each UWB module (1101; 1102; 1103; 1104; 110 i ), the signal processing unit (113 i ) is configured to: compare the value of the calibrated distance (d cal ) with a predetermined threshold, and generate an alarm signal when the value of the calibrated distance is greater than the threshold.

8. The set (100) according to any one of claims 1 to 7, characterized in that, In each UWB module (1101; 1102; 1103; 1104; 110 i )), the signal processing unit (113 i ) is configured to: - By comparing the absolute value of the difference between the measured spacing (E m ) and the corresponding actual spacing value (E r ) with a predetermined threshold to detect a faulty module among the UWB modules (1101; 1102; 1103; 1104; 110 i ) of the set; and - When the presence of a faulty module among the UWB modules (1101; 1102; 1103; 1104; 110 i ) of the set (100) has been detected, the UWB module identified as faulty is manipulated to be deactivated.

9. A system for locating a user, intended to be integrated into a motor vehicle (10) and comprising a set (100) as claimed in any one of claims 1 to 8, characterized in that, It further includes a central computer (200) that is connected to each of the UWB modules (1101; 1102; 1103; 1104; 110 i ) of the set (100) and is configured to: - Receive the current distance value between the UWB module and the badge (300) from each respective UWB module of the UWB modules; and - Calculate a current position of the badge (300) relative to the vehicle by means of the current distance value.

10. The system according to claim 9, wherein, The central computer (200) is further configured to: manipulate the locking and / or unlocking of at least one door of the motor vehicle (10) especially according to at least one current position of the badge (300) relative to the vehicle (10).

11. The system according to claim 10, wherein It further includes a badge (300) which is intended to be carried by a user wishing to enter the motor vehicle (10) and includes a memory storing an authentication code.

12. A vehicle (10) comprising an assembly (100) according to any one of claims 1 to 8.

13. A method implemented in each UWB module (1101; 1102; 1103; 1104; 110 i ) of a set (100) as claimed in any one of claims 1 to 8, characterized in that: The method includes the following steps: a / Transmit (401) a UWB module query signal (SE(i)) destined for at least one of the other three UWB modules, and receive (402) at least one UWB module response signal (SR(i,j)) for a response; b / Store (403) second timestamp data (Ti) related to the moment of transmission of the UWB module query signal and the moment of reception of the UWB module response signal; c / Calculate (404) a current value of a second time-of-flight (Δt) corresponding to a propagation duration of a radio frequency signal between the UWB module and a respective one of three other UWB modules by means of second timestamp data, and use (405) the current value of the second time-of-flight to calculate a corresponding measured spacing (E m ); d / Calculate the difference (406) between the measured spacing (E m ) and the corresponding actual spacing value (E r ) to obtain the value of the calibration distance (d cal ); then e / Use the value of the calibrated distance to calculate at least one current distance value between the UWB module and the badge thereafter.

14. The method according to claim 13, wherein Steps a / to d / are carried out a plurality of times during the lifetime of the assembly (100) according to any one of claims 1 to 7, and step e / is carried out each time using the last calculated value of the calibrated distance.

15. The method according to claim 13 or 14, characterized in that, The method further includes the following steps: - By comparing the absolute spacing difference between the measured spacing (E m ) and the corresponding actual spacing value (E r ) with a predetermined threshold to detect a faulty module among the UWB modules (1101; 1102; 1103; 1104; 110 i ) of the set (100); and - When the presence of a faulty module among the UWB modules (1101; 1102; 1103; 1104; 110 i ) of the set (100) has been detected, the UWB module identified as faulty is manipulated to be deactivated.

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