Method for activating a vehicle function and associated activation device

Abstract

The present invention relates to a method for activating a vehicle function from a "hands-free" access device carried by a user using an activation device, the method comprising the steps of: transmitting a request to a plurality of access devices through ultrahigh frequency; receiving the request and acquiring values from magnetometers, accelerometers and gyroscopes integrated into the devices for a predetermined duration of each device; determining a proximity vector for each device based on the values thus acquired; if the number of access devices is greater than a threshold: 0 determining a correlation coefficient between various proximity vectors; 0 merge the access devices with the correlated proximity vectors; 0 comparing at least one received transmission parameter from the same group; 0 selecting the access device from the same communication group according to the value of the at least one parameter; 0 detecting the presence of the user in a predetermined area and authenticating the user over ultra-wideband using the access device thus selected.

Description

[Technical field]

[0001] The present invention relates to a method for activating a function of a motor vehicle and an associated activation device. The invention is particularly, but not exclusively, applicable to a function involving hands-free access to a motor vehicle using a smartphone, wherein the function involves, for example, locking and unlocking opening elements of the motor vehicle.

[0002] In motor vehicles, it is known practice to use devices for activating vehicle functions that are capable of detecting the presence of a hand or foot of a vehicle user, thereby allowing the locking or unlocking of all or some of the vehicle's opening elements, such as the doors or the trunk. For example, the detection of the presence of a user's hand on or in front of a door handle, combined with an identifier identifying a "hands-free" access device carried by the user, allows the locking and unlocking of these opening elements.

[0003] "Hands-free" access systems for accessing motor vehicles allow an authorized user to lock and / or unlock the opening elements of their vehicle without having to physically press a button on the key. For this purpose, the vehicle recognizes a portable device, such as a key fob, a remote control, or even a key, carried by the user, and if the key fob, the remote control, or the key is located in a predetermined area around the vehicle or in the vehicle and is recognized as belonging to the vehicle, the vehicle automatically locks / unlocks its opening elements according to the user's intention, without the user having to physically manipulate the key.

[0004] To this end, when the user approaches the vehicle, communication is established via a wireless communication link between a “hands-free” access device (e.g. an electronic key fob or a smartphone) and a device for activating vehicle functions in order to authenticate the access device using its identifier.

[0005] To this end, the activation device comprises at least one radiofrequency antenna allowing the reception of an identifier sent by the "hands-free" access device. The activation device is connected to the electronic control unit (ECU) of the vehicle to which it transmits the identifier.

[0006] According to prior art, the access device is typically an electronic key fob. The signal received by the activation device's antenna (containing the access device's identifier) ​​is transmitted via RF (radio frequency) or LF (low frequency) waves. By measuring the strength of the RF signal received by the portable device (via the antenna and electronic control unit) from the vehicle (more commonly known as an RSSI (Received Signal Strength Indication) measurement), the portable device can be accurately located around the vehicle. The strength measurement of each signal received by the portable device from each of the multiple RF antennas located on the vehicle V is received and analyzed by the activation device mounted on the vehicle, which then determines the portable device's position relative to the RF antenna (i.e., relative to the vehicle) via triangulation.

[0007] Certain actions specific to the positioning area are automatically performed according to the positioning of the portable device identified by the vehicle in the positioning area, ie, unlocking / locking in advance or turning on the welcome lighting in the passenger compartment.

[0008] However, it is becoming increasingly common to use mobile phones to perform authentication functions, which avoids the need for dedicated electronic key fobs and thus limits the number of devices. Most mobile phones do not have RF or LF communication devices. Therefore, it is necessary to adapt a "hands-free" access and / or start system for the vehicle so that the vehicle can also use other communication standards (such as ultra-wideband, UWB, or Bluetooth Low Energy). Mobile phones now operate over wireless or Wi-Fi (Wireless Fidelity) communications, rather than solely via radio and low-frequency (RF and LF) waves. Ultra-wideband (UWB) is a radio modulation technology based on the transmission of very short pulses (typically less than a nanosecond). Consequently, the bandwidth can reach very large values.

[0009] For its part, Bluetooth communications involve communication at frequencies in the range of approximately 2.4 GHz.

[0010] The disadvantage of using Bluetooth (UHF) is that it doesn't accurately locate mobile phones. Bluetooth is subject to a lot of interference, which can cause inaccurate positioning. In addition, mobile phone positioning can vary significantly from phone to phone.

[0011] Therefore, it is proposed to use ultra-wideband to locate mobile phones more accurately.

[0012] Thus, a method for activating a vehicle function using a mobile phone involves:

[0013] detecting the remote presence of an access device (i.e., within a 100 m area around the vehicle) via Bluetooth communication, and establishing a first Bluetooth communication link between the access device and the activating device;

[0014] identifying an identifier received by the vehicle via Bluetooth;

[0015] If necessary, remotely activate certain vehicle functions, for example, unlock the vehicle, activate the climate control, and at the same time, for example, turn on the air conditioning, heating, radio, or indeed,

[0016] Detecting the close presence of an access device via UWB (i.e., within a radius of a few meters (e.g., 10 m) around the vehicle) and precisely locating the location of the device;

[0017] The vehicle function, i.e., unlocking, is activated when a device is detected approaching the vehicle door or a hand is detected in close contact with the vehicle door.

[0018] The activation method thus described works reliably when communication is established between the vehicle and the mobile phone. However, when the number of access devices connected to the vehicle via UWB increases (e.g. not only mobile phones but also smart watches), the probability of collisions between UWB transmissions made by various devices with the vehicle increases significantly, thus affecting the positioning of the devices. Figure 1 This is shown in , which shows the probability P of a collision between UWB transmissions as a function of the number of connected devices. Based on four devices connected simultaneously to the vehicle, the probability of a collision appears to be 40%, i.e. 40% of the transmissions are not reliable enough to establish an accurate position fix.

[0019] In a scenario where eight devices are connected to the vehicle simultaneously, positioning becomes completely impossible as the probability of transmissions colliding is close to 100%.

[0020] The activation method of the prior art prioritizes activating the first access device detected. However, when the user moves towards the vehicle, the access device is sometimes not the most reliable access device for establishing a precise location. Therefore, not considering other devices is harmful.

[0021] The present invention therefore proposes a method for activating a vehicle function and an associated activation device for detecting a user's intention to unlock (or lock) his vehicle. [Summary of the invention]

[0022] The present invention relates to a method for activating a vehicle function from a "hands-free" access device carried by a user, using an activation device equipped with a magnetometer, an accelerometer and a gyroscope, wherein the activation of the function is triggered by detecting the presence of the device in a predetermined area around the vehicle and according to an authentication result associated with the device, the activation device comprising at least one transceiver capable of communicating with the device via ultra-wideband and ultra-high frequency, the method being characterized in that it comprises the following steps:

[0023] a. Transmit requests to multiple access devices via UHF;

[0024] b. receiving the request by the plurality of devices and obtaining values ​​from the magnetometer, the accelerometer, and the gyroscope for a predetermined duration for each device;

[0025] c. determining a proximity vector for each device based on the values ​​of the magnetometer, the accelerometer, and the gyroscope so acquired during the predetermined duration;

[0026] d. If the number of access devices is greater than the threshold, then:

[0027] i. Determine the correlation coefficient between various proximity vectors;

[0028] ii. merging these devices having proximity vectors whose mutual correlation coefficient is greater than a predetermined correlation coefficient value into a communication group;

[0029] iii. comparing at least one transmission parameter received by the activation device between the access devices from the same communication group;

[0030] iv. selecting the access device from the access devices from the same communication group according to the value of the at least one parameter;

[0031] v. Detecting the presence of the user in a predetermined area and authenticating the user via ultra-wideband using the access device thus selected.

[0032] Suitably, the transmission parameters are:

[0033] a. The total strength of the received transmission; or

[0034] b. signal-to-noise ratio; or

[0035] c. Power spectral density, and is characterized in that the access device with the highest total strength or signal-to-noise ratio or spectral density is selected.

[0036] Alternatively, the received transmission parameter is a time of flight or a visibility type of the received transmission and is characterized in that the access device transmitting with minimum time of flight or with direct visibility is selected.

[0037] The present invention also relates to a device for activating a vehicle function, the device being equipped with a magnetometer, an accelerometer and a gyroscope, wherein the activation of the function is triggered by detecting the presence of a "hands-free" access device in a predetermined area around the vehicle and according to an authentication result associated with said device, the activation device comprising at least one transceiver capable of communicating with said device via ultra-wideband and ultra-high frequency, the device being characterized in that, in a first embodiment of the invention, it comprises:

[0038] a UHF receiving means for receiving values ​​associated with the gyroscope, the magnetometer, and the accelerometer, wherein the values ​​originate from a plurality of access devices and are acquired within a predetermined duration;

[0039] b. means for determining a proximity vector for each device based on the values ​​of the magnetometer, the accelerometer, and the gyroscope so acquired during the predetermined duration;

[0040] c. means for determining the correlation coefficient between various proximity vectors;

[0041] d. means for merging the proximity vectors of the devices having a mutual correlation coefficient greater than a predetermined correlation coefficient value into a communication group;

[0042] e. means for comparing at least one received transmission parameter between these access devices from the same communication group;

[0043] f means for selecting the access device from among the access devices from the same communication group according to the value of the at least one parameter;

[0044] g. means for detecting the presence of the user in a predetermined area and for authenticating the user via ultra-wideband using the access device thus selected.

[0045] In a second embodiment of the invention, a device for activating a vehicle function is equipped with a magnetometer, an accelerometer and a gyroscope, wherein activation of the function is triggered by detecting the presence of a "hands-free" access device in a predetermined area around the vehicle and based on an authentication result associated with said device, the activation device comprising at least one transceiver capable of communicating with said device via ultra-wideband and ultra-high frequency, the device being characterized in that it comprises:

[0046] a. UHF receiving means for receiving proximity vectors from a plurality of access devices, the proximity vectors being determined based on the values ​​associated with the magnetometer, the accelerometer, and the gyroscope so acquired during the predetermined duration;

[0047] b. means for determining the correlation coefficient between various proximity vectors;

[0048] c. means for merging the proximity vectors of the devices having a mutual correlation coefficient greater than a predetermined correlation coefficient value into a communication group;

[0049] d. means for comparing at least one received transmission parameter between these access devices from the same communication group;

[0050] e. means for selecting the access device from the plurality of access devices from the same communication group according to the at least one received transmission parameter;

[0051] f. Means for detecting the presence of the user in a predetermined area and for authenticating the user via ultra-wideband using the access device thus selected.

[0052] Suitably, the parameter is the total strength of the received transmission, or the signal-to-noise ratio, or the power spectral density.

[0053] Alternatively, the parameter is the time of flight or visibility type of the received transmission.

[0054] The invention also applies to any computer program product comprising program code instructions for performing the steps of the method according to the features listed above, when said program is executed on a computer.

[0055] In a second embodiment, the present invention also relates to an access device, characterized in that the access device comprises: a magnetometer; an accelerometer; a gyroscope; means for acquiring values ​​of the magnetometer, the accelerometer and the gyroscope within a predetermined duration; means for determining a proximity vector based on the values ​​of the magnetometer, the accelerometer and the gyroscope thus acquired within the predetermined duration; and means for ultra-high frequency transmission of the proximity vector thus determined.

[0056] Furthermore, for a first embodiment, the invention relates to any access device, characterized in that it comprises: a magnetometer; an accelerometer; a gyroscope; means for acquiring the values ​​of the magnetometer, the accelerometer and the gyroscope over a predetermined duration; and means for ultrahigh frequency transmission of said values ​​thus determined.

[0057] Finally, the invention applies to any motor vehicle comprising an activation device according to any one of the features listed above. [Brief Description of the Drawings]

[0058] Further features and advantages of the present invention will become more clearly apparent on reading the following description. This description is purely illustrative and should be read with reference to the accompanying drawings, in which:

[0059] [ Figure 1 ]: Figure 1 is a graph showing the probability of transmission collisions between the devices and the vehicle depending on the number of access devices connected to the vehicle via UWB;

[0060] [ Figure 2 ]: Figure 2 is a graph showing continuous measurements of an accelerometer, a gyroscope, and a magnetometer included in an access device for various states of a user (i.e., standing, approaching, turning, moving away, and standing again);

[0061] [ Figure 3 ]: Figure 3 is a three-dimensional graph showing a proximity vector of an access device between three consecutive movement moments along an axis showing speed, orientation, and number of steps;

[0062] [ Figure 4 ]: Figure 4 is a three-dimensional graph showing Figure 5Approach vectors of four access devices around the vehicle are shown along axes showing speed, orientation, and number of steps during five consecutive moments of movement of the user;

[0063] [ Figure 5 ]: Figure 5 is a schematic diagram showing three users each carrying at least one access device and each performing a different movement relative to a vehicle;

[0064] [ Figure 6 ]: Figure 6 is a diagram showing seven access devices that are combined according to the user who carries them according to the activation method of the present invention;

[0065] [ Figure 7 ]: Figure 7 is a flow chart showing an activation method according to the present invention;

[0066] [ Figure 8 ]: Figure 8 An activation device according to the invention is schematically shown. [Specific implementation method]

[0067] Figure 5 A motor vehicle V equipped with an activation device D according to the present invention is shown. The activation device D includes four antenna modules EM1, EM2, EM3, and EM4 for transmitting and receiving via ultra-wideband UWB and ultra-high frequency BLE. These four antenna modules are capable of communicating with a portable access device P1 carried by a user U in zones Z1 and Z2 around the vehicle V via ultra-wideband UWB and ultra-high frequency Bluetooth Low Energy (BLE). When the portable device P1 is in a long-range zone Z2 around the vehicle, BLE communication is activated; when the portable device P1 is in a short-range zone Z1 around the vehicle V or in the passenger compartment Z0 of the vehicle V, ultra-wideband communication is activated.

[0068] The activation device D further comprises a central control unit 10 electrically connected to all antenna modules EM1 , EM2 , EM3 and EM4 .

[0069] The central control unit 10 allows the transmission and reception of UWB and Bluetooth (BLE) data to be managed via the antenna modules. This is known in the art and will not be described in further detail herein.

[0070] Ultra-wideband (UWB) communication is understood to mean radio frequency communication based on the transmission of pulses of very short duration (typically less than one nanosecond). The bandwidth can therefore reach very large values ​​between 250 MHz and 500 MHz.

[0071] Bluetooth LE (Bluetooth Low Energy) communication is understood to mean ultra-high frequency communication in the range of approximately 2.4 GHz.

[0072] According to prior art, when the number of portable access devices P1, P2, ..., Pn connected to an activation device D via ultra-wideband (UWB) exceeds a predetermined threshold, the number of collisions between transmissions originating from said devices is such that precise positioning of each device is impossible.

[0073] The portable devices P1, ..., Pn may be smart phones, smart watches, tablet computers, or the like.

[0074] The present invention proposes an activation method and device for overcoming this shortcoming of the prior art.

[0075] In this case, according to the present invention, each portable device P1 , P2 , . . . , Pn is provided with a magnetometer MG, an accelerometer Acc and a gyroscope Gyr.

[0076] If an orthogonal coordinate system (O, x, y, z) is defined, the accelerometer Acc provides acceleration measurements AccX, AccY, AccZ of the access device Pi in three dimensions. Similarly, the gyroscope Gyr provides orientation measurements GyrX, GyrY, GyrZ in three dimensions, and finally, the magnetometer MG provides values ​​representing the yaw MG1, pitch MG2, and roll MG3 of the access device Pi in three dimensions. This is Figure 2 It was displayed in . Figure 2 Shown are the values ​​of acceleration AccX, AccY, AccZ, orientation GyrX, GyrY, GyrZ, and yaw MG1, pitch MG2, and roll MG3 in three dimensions of a portable device P1 carried by a user U completing the following series of several movements:

[0077] a. During the first movement S1, the user U stands and walks towards the vehicle V;

[0078] b. During the second movement S2, the user U continues walking and approaches the vehicle V;

[0079] c. During the third movement S3, the user U completes the backward turn and turns 180°;

[0080] d. During the fourth movement S4, the user leaves the vehicle V;

[0081] e. During the last movement S5, user U remains standing and continues to move away from the vehicle.

[0082] According to the present invention, the portable devices P1, P2, ..., Pn are also capable of measuring the values ​​of the gyroscopes GyrX, GyrY, GyrZ, the accelerometers AccX, AccY, AccZ and the magnetometers MG1, MG2, MG3 within a predetermined duration Δt and transmitting the values ​​thus measured to the activation device D via ultra-high frequency (BLE).

[0083] According to the invention, the activation device D is for its part able to:

[0084] a. Receiving values ​​related to the gyroscopes GyrX, GyrY, GyrZ, the magnetometers MG1, MG2, MG3, and the accelerometers AccX, AccY, AccZ via ultra-high frequency (BLE), wherein the values ​​originate from a plurality of access devices P1, P2, ..., Pn and are acquired within a predetermined duration Δt;

[0085] b. Determine the proximity vector of each device P1, P2, ..., Pn based on the values ​​of the magnetometers MG1, MG2, MG3, the accelerometers AccX, AccY, AccZ and the gyroscopes GyrX, GyrY, GyrZ thus acquired within a predetermined duration

[0086] c. Determine various approach vectors The correlation coefficient ki between them;

[0087] d. The devices P1, P2, ..., Pn having a mutual correlation coefficient ki greater than a predetermined correlation coefficient value ks are close to the vector merged into the communication group G1, G2, ..., Gk;

[0088] e. Comparison of transmission parameters received by the activation device D between access devices from the same communication group G1, G2, ..., Gn;

[0089] f according to the received transmission parameters, from the same communication group G1, G2, ..., Gk access device P1, P2, ..., Pn select access device Pi;

[0090] g. Detecting the presence of the user U in the predetermined zone Z2, Z1 and authenticating the user via ultra-wideband using the access device Pi thus selected.

[0091] To this end, activating device D comprises:

[0092] a. a BLE receiving device M1 for receiving values ​​related to gyroscopes GyrX, GyrY, GyrZ, magnetometers MG1, MG2, MG3 and accelerometers AccX, AccY, AccZ, wherein said values ​​originate from a plurality of access devices P1, P2, ..., Pn and are determined within a predetermined duration Δt;

[0093] b. for determining the proximity vector of each device P1, P2, ..., Pn based on the values ​​of the magnetometers MG1, MG2, MG3, the accelerometers AccX, AccY, AccZ and the gyroscopes GyrX, GyrY, GyrZ thus acquired within a predetermined duration Δt. Device M2;

[0094] c. Used to determine various approach vectors The correlation coefficient ki between the devices M3;

[0095] d for having a mutual correlation coefficient ki greater than a predetermined correlation coefficient value ks proximity vector device P1, P2, ..., Pn merged into the same communication group G1, G2, ..., Gk means M4;

[0096] e for comparing the parameters of the transmission received by the activation device D between the access devices from the same communication group G1, G2, ..., Gn means M5;

[0097] f for using the parameters from the same communication group G1, G2, ..., Gk access device P1, P2, ..., Pn select access device Pi means M6;

[0098] g. Means M7 for detecting the presence of a user U in a predetermined zone Z2, Z1 and for authenticating the user by ultra-wideband (UWB) using the access device Pi thus selected.

[0099] The receiving means M1, the means for determining the approach vector M2, the means for determining the correlation coefficient M3, the merging means M4, the comparing means M5, the selecting means M6 and the detecting means M7 are included in the central control unit 10, for example, in the form of software. Figure 8 It was displayed in .

[0100] The selection means M6 allow the selection of an access device Pi as a function of at least one of the parameters of the received transmission, ie as a function of one of the following communication parameters or as a function of a combination of the following parameters:

[0101] The parameter may be composed of one of the following parameters or a combination of several of the following parameters:

[0102] a. The total strength of the received transmission RSSImax;

[0103] b. Signal-to-noise ratio Rsmax;

[0104] c. Power spectral density Dmax;

[0105] d. Time of flight TOFmin;

[0106] e. The direct or indirect visibility type Vdi of the transmission.

[0107] Suitably, the selection means M6 selects from each communication group G1, ..., Gk an access device Pi having:

[0108] a. The highest total strength RSSimax of the transmission received by the activated device D;

[0109] b. The highest signal-to-noise ratio Rsmax of the transmission received by the activated device D;

[0110] c. The highest power spectral density Dmax of the transmission received by the active device D;

[0111] d. The shortest time of flight TOFmin of a transmission received by an activated device D;

[0112] e. Direct visibility Vdi of the transmission received by the active device D, also called “line of sight”.

[0113] The use of at least one parameter according to the above criteria allows the selection means M6 to select from each communication group G1 , ..., Gk the access device Pi that is most reliable for communication with the activating device D. Said parameters are known to those skilled in the art and will not be described in further detail herein.

[0114] The activation device D further comprises a processor 100 and a memory 101 (see Figure 8 ), which stores instructions for configuring the processor to perform certain specific processing operations (in particular, implementing the steps of the method for activating a vehicle function according to an embodiment described below).

[0115] In a second embodiment of the invention, the means M2 for determining the proximity vector are not included in the activation device D, but in the portable devices P1, P2, ..., Pn. Said devices P1, P2, ..., PN are thus able to determine the proximity vector from the values ​​of the gyroscope Gyr, the magnetometer MG and the accelerometer Acc that have been acquired during a predetermined duration Δt. And the activating device D, for its part, can receive said proximity vectors thus determined by the device itself from a plurality of access devices P1 , P2 , . . . , Pn.

[0116] We will now describe Figure 7 The activation method according to the present invention is shown in FIG.

[0117] During a first step E1 , a BLE communication is established between an activating device D and a plurality of portable devices P1 , P2 , . . . , Pn located within the BLE communication range around a vehicle V. During this communication, the activating device D sends a request R to the plurality of access devices P1 , P2 , . . . , Pn.

[0118] During a second step E2 , a plurality of access devices P1 , P2 , . . . , Pn receive the request R and they then measure, within a predetermined duration Δt, the values ​​of the magnetometers MG1 , MG2 , MG3 , accelerometers AccX, AccY, AccZ , gyroscopes GyrX, GyrY, GyrZ integrated in these access devices.

[0119] During a third step E3, in a preferred embodiment of the method according to the invention, said values ​​acquired by the plurality of access devices P1, ..., Pn are transmitted via ultra-high frequency (BLE) to the activating device D, said device D then using said values ​​it has received to determine at least one or more successive proximity vectors of each device P1, ..., Pn.

[0120] It is worthwhile to determine at least two consecutive approach vectors between three consecutive movement moments of the user U (ie within two consecutive predetermined time durations).

[0121] In a second embodiment of the method according to the invention, this step of determining the proximity vector is performed by the access devices P1 , . . . , Pn themselves by means of values ​​they have themselves measured.

[0122] Used to calculate or determine the proximity vector based on the values ​​of the gyroscope GyrX, GyrY, GyrZ, the magnetometer MG1, MG2, MG3 and the accelerometer AccX, AccY, AccZ continuously acquired over time The method is known to those skilled in the art. This method is called "dead reckoning navigation" or "pedestrian dead reckoning"; it is a navigation method known in the art that estimates the speed and direction of an object or person. Figure 3 It was displayed in .

[0123] Figure 3 is a series of two approach vectors along the axes of orientation O, velocity V and number of steps S in three dimensions between consecutive instants t0, t1 and t2 (i.e., within two consecutive predetermined durations Δt1 (between t0 and t1) and Δt2 (between t1 and t2) 's curve graph.

[0124] During a fourth step E4, the number N of access devices currently connected via ultra-high frequency (BLE) to the vehicle V is counted. If the number N of connected devices is less than a threshold value Nmax, the method returns to the second step E2, i.e., the gyroscope values, magnetometer values ​​and accelerometer values ​​are measured for each of the plurality of access devices P1, ..., Pn currently connected via ultra-high frequency (BLE) to the device D, including "new" access devices that have appeared since the last BLE connection.

[0125] Otherwise, if the number N of connected devices is greater than the threshold Nmax, the activation method according to the invention proposes, in a fifth step E5, to determine the various proximity vectors The correlation coefficient ki between them.

[0126] The calculation of the correlation coefficient ki is known to those skilled in the art; it can use linear regression or any other method to determine the mathematical connection between two approach vectors originating from two different access devices; more specifically, when two approach vectors have substantially the same orientation O, the same movement speed V and the same number of steps S, there is a strong correlation coefficient ki between these two approach vectors.

[0127] It should be noted that in the case where the number N of devices connected to the vehicle V can vary over time, it is necessary to determine the proximity vector as early as possible in the method (ie upon receipt of the BLE request R from the activation device D).

[0128] In practice, the generation of the approach vector may be time-consuming. If other access devices P1 , . . . , Pn are connected to the vehicle V, the approach vector needs to be obtained as early as possible when the user approaches the vehicle in order to implement the method according to the invention.

[0129] Then, during a sixth step E6, the access devices P1, P2, ..., Pn whose proximity vectors have a correlation coefficient ki greater than a predetermined correlation coefficient value ks (for example, ks=0.7) are merged into the communication group G1, G2, ..., Gk. In fact, the activation method according to the invention is based on the Applicant's discovery that the access devices P1, P2, ..., Pn carried by the same user U1, U2, U3 have similar and strongly correlated proximity vectors. Therefore, as explained below, the method proposes not to use all the access devices P1, ..., Pn carried by the same user to locate and authenticate the user, but only to use the access devices with which the communication with the activation device D is most reliable, that is, using the parameters of the transmission received as described below.

[0130] Figure 4 Four approach vectors are shown according to orientation O, velocity V and number of steps S These four approach vectors are respectively targeted at five consecutive moments. Figure 5 The four different access devices P1, P2, P3, and P4 shown appear to be close to the vector and are strongly correlated; in fact, they have the same direction, the same speed and the same number of step lengths over time. In fact, the access devices P1 and P4 are carried by the same user U3, as Figure 5 What is shown.

[0131] Figure 6 Another example is shown in . Figure 6 Seven portable access devices P1, P2, ..., P7 are shown, all connected simultaneously to an activation device D. The devices P1, P2, P3 have strongly correlated proximity vectors (not shown); according to the invention, it is concluded that these devices P1, P2, P3 are carried by the same user, and the method therefore merges these devices into a first communication group G1.

[0132] Similarly, devices P5, P6, P7 have strongly correlated proximity vectors (not shown); according to the present invention, it is concluded that these devices are carried by the second user. Therefore, the method merges these devices into the second communication group G2.

[0133] The proximity vector of access device P4 has no correlation with the proximity vectors of the other six access devices; therefore, access device P4 appears to be the only device carried by the third user and alone constitutes the third communication group G3.

[0134] During a seventh step E7 , a comparison is made between access devices in the same communication group G1 , G2 , . . . , Gk using at least one reception parameter of the transmission received by the active device D.

[0135] The parameter may be composed of one of the following parameters or a combination of several of the following parameters:

[0136] a. The total strength of the received transmission RSSImax;

[0137] b. Signal-to-noise ratio Rsmax;

[0138] c. Power spectral density Dmax;

[0139] d. Time of flight TOFmin;

[0140] e. The direct or indirect visibility type Vdi of the transmission.

[0141] Furthermore, during an eighth step E8 , an access device Pi is selected from the communication group G1 , . . . , Gk according to one of the parameters listed above or according to a combination of several of the parameters listed above.

[0142] More specifically, according to the present invention, an access device Pi is selected from all access devices P1, ..., Pn from the same communication group G1, ..., Gk that has:

[0143] a. The highest total strength RSSimax of the transmission received by the activated device D;

[0144] b. The highest signal-to-noise ratio Rsmax of the transmission received by the activated device D;

[0145] c. The highest power spectral density Dmax of the transmission received by the active device D;

[0146] d. The shortest time of flight TOFmin of a transmission received by an activated device D;

[0147] e. Direct visibility Vdi of the transmission received by the active device D, also called “line of sight”.

[0148] Using at least one parameter according to the above criteria allows selecting from the communication groups G1 , ..., Gk the access device Pi whose communication with the activating device D is most reliable. Said parameters are known to the person skilled in the art and will not be described in further detail herein.

[0149] During a ninth and final step E9 , the positioning of the user U and his ultra-wideband (UWB) authentication are then performed using only the access devices Pi thus selected for each communication group G1 , . . . , Gk.

[0150] This is Figure 6 The received transmission strength RSSImax parameter is shown in Figure 1. In the first group G1, the access device with the highest received transmission strength is device P3, which has a strength of -78 dBm. Therefore, only one access device (i.e., access device P3) is used to establish the location of the first user U1 carrying access devices P1, P2, and P3.

[0151] In the second group, the access device with the highest reception strength is device P7, which is equal to -68 dBm; therefore, the location of the second user U2 carrying access devices P5, P6, and P7 is established with only one access device, namely access device P7.

[0152] In the case that the third user U3 carries only one access device P4, the positioning and authentication of the user are established through the only device (ie, device P4) carried by the third user U3.

[0153] Thus, the user is located and authenticated by selecting only one access device from among the multiple access devices carried by the user. This reduces the total number of devices connected to the vehicle and, therefore, the number of transmission collisions. As a result, ultra-wideband communication is more reliable and more efficient, resulting in more accurate positioning and more secure authentication.

[0154] The invention is therefore advantageous because it allows overcoming the main drawbacks of the prior art by selecting the access device with which the vehicle can communicate.

[0155] The present invention is furthermore ingenious because its implementation is simple and inexpensive, since it is implemented by software means.

Claims

1. A method for activating a vehicle function from a "hands-free" access device (SD) carried by a user (U) using an activation device (D), the access device being equipped with a magnetometer (MG), an accelerometer (Acc) and a gyroscope (Gyr), wherein The activation of the function is triggered by detecting the presence of the device (SD) in a predetermined zone (Z1, Z2) around the vehicle (V) and according to an authentication result related to the device (SD), the activation device comprising at least one transceiver (EM1, EM2, EM3, EM4) capable of communicating with the device via ultra-wideband (UWB) and ultra-high frequency (BLE), the method being characterized in that it comprises the following steps: a) transmitting a request (R) to multiple access devices (P1, ..., Pi) via UHF; b) the plurality of access devices (P1, ..., Pi) receiving the request and acquiring values ​​from the magnetometer (MG1, MG2, MG3), the accelerometer (AccX, AccY, AccZ) and the gyroscope (GyrX, GyrY, GyrZ) within a predetermined duration (Δt) of each device; c) determining a proximity vector for each device based on the values ​​of the magnetometer (MG1, MG2, MG3), the accelerometer (AccX, AccY, AccZ) and the gyroscope (GyrX, GyrY, GyrZ) thus acquired during the predetermined duration d) If the number of access devices (N) is greater than the threshold (Nmax), then: i) Determine various approach vectors The correlation coefficient (ki) between ii) merging those devices having proximity vectors with a mutual correlation coefficient (ki) greater than a predetermined correlation coefficient value (ks) into a communication group (G1, ..., Gk); Then, for each communication group: iii) comparing at least one transmission parameter (RSSImax, Rsmax, Dmax, TOFmin, Vdi); iv) selecting the access device from the plurality of access devices (P1, ..., Pi) from the same communication group (G1, ..., Gk) according to the value of the at least one parameter (RSSImax, Rsmax, Dmax, TOFmin, Vdi); v) Detecting the presence of the user in a predetermined zone (Z1, Z2) and authenticating the user by ultra-wideband (UWB) using the access device (Pi) thus selected.

2. Activation method according to the preceding claim, characterized in that The received transmission parameter is the total strength (RSSImax), or the signal-to-noise ratio (RSmax), or the power spectral density (Dmax) of the received transmission, and is characterized in that the access device (Pi) having the highest total strength, signal-to-noise ratio or spectral density is selected.

3. The activation method according to claim 1, wherein: The received transmission parameter is the time of flight (TOFmin) or the type of visibility (Vdi) of the received transmission and is characterized in that the access device (Pi) is selected that transmits with minimum time of flight or with direct visibility.

4. A device (D) for activating a vehicle function, wherein The activation of the function is triggered by detecting the presence of a "hands-free" access device (SD) equipped with a magnetometer (MG), an accelerometer (Acc) and a gyroscope (Gyr) in a predetermined zone (Z1, Z2) around the vehicle (V) and according to an authentication result associated with said device, said activation device comprising at least one transceiver (EM1, EM2, EM3, EM4) capable of communicating with said device via ultra-wideband (UWB) and ultra-high frequency (BLE), said device being characterized in that it comprises: a) an ultra-high frequency (UWB) receiving device (M1) for receiving values ​​related to the gyroscope (GyrX, GyrY, GyrZ), the magnetometer (MG1, MG2, MG3) and the accelerometer (AccX, AccY, AccZ), wherein said values ​​originate from a plurality of access devices (P1, ..., Pi) and are acquired within a predetermined time duration (Δt); b) for determining a proximity vector for each device based on the values ​​of the magnetometer, the accelerometer and the gyroscope so acquired during the predetermined duration device (M2); c) means (M3) for determining correlation coefficients (ki) between the various proximity vectors based on a comparison between the number of access devices (N) and a threshold value (Nmax); d) means (M4) for merging into a communication group (G1, ..., Gk) those access devices (P1, ..., Pi) having proximity vectors with a mutual correlation coefficient (ki) greater than a predetermined correlation coefficient value (ks); e) for comparing at least one received transmission parameter (RSSImax, Rsmax, Dmax, TOFmin, Vdi) device (M5); f) means (M6) for selecting the access device (Pi) from among the access devices from the same communication group as a function of the value of the at least one parameter; g) means (M7) for detecting the presence of the user in a predetermined zone (Z1, Z2) and for authenticating the user by ultra-wideband (UWB) using the access device (Pi) thus selected.

5. A device for activating a vehicle function, wherein: The activation of the function is triggered by detecting the presence of a "hands-free" access device (SD) equipped with a magnetometer (MG), an accelerometer (Acc) and a gyroscope (Gyr) in a predetermined zone (Z1, Z2) around the vehicle (V) and according to an authentication result associated with said device, said activation device comprising at least one transceiver (EM1, EM2, EM3, EM4) capable of communicating with said device via ultra-wideband (UWB) and ultra-high frequency (BLE), said device being characterized in that it comprises: a) an ultra-high frequency receiving device (M1'), which is used to receive proximity vectors from multiple access devices (P1, ..., Pi) the approach vectors being determined based on the values ​​related to the magnetometer (MG1, MG2, MG3), the accelerometer (AccX, AccY, AccZ) and the gyroscope (GyrX, GyrY, GyrZ) thus acquired during the predetermined duration (Δt); b) means (M3) for determining the correlation coefficients (ki) between the various proximity vectors based on a comparison between the number of access devices (N) and a threshold value (Nmax); c) means (M4) for merging access devices having proximity vectors with a mutual correlation coefficient greater than a predetermined correlation coefficient value (ks) into a communication group (G1, . . . , Gk); d) for comparing at least one received transmission parameter (RSSImax, Rsmax, Dmax, TOFmin, Vdi) device (M5); e) means (M6) for selecting the access device (Pi) from the plurality of access devices from the same communication group according to the at least one received transmission parameter; f) means (M7) for detecting the presence of the user in a predetermined zone (Z1, Z2) and for authenticating the user by ultra-wideband (UWB) using the access device (Pi) thus selected.

6. Activation device (D) according to claim 4 or 5, characterized in that The parameter is the total strength of the received transmission (RSSImax), or the signal-to-noise ratio (Rsmax), or the power spectral density (Dmax).

7. Activation device (D) according to claim 4 or 5, characterized in that The parameter is the time of flight (TOFmin) or visibility type (Vdi) of the received transmission.

8. A computer program product comprising program code instructions for executing the steps of the method according to claim 1 when said program is executed on a computer.

9. A portable access device (SD), characterized in that The device comprises: a magnetometer (MG); an accelerometer (Acc); a gyroscope (Gyr); means for acquiring values ​​of the magnetometer (MG1, MG2, MG3), the accelerometer (AccX, AccY, AccZ) and the gyroscope (GyrX, GyrY, GyrZ) within a predetermined duration (Δt); and means for determining a proximity vector based on the values ​​of the magnetometer, the accelerometer and the gyroscope thus acquired within the predetermined duration. means (M3); and means for ultra-high frequency (BLE) transmission of the proximity vector thus determined.

10. A portable access device (SD), characterized in that The device comprises: a magnetometer (MG); an accelerometer (Acc); a gyroscope (Gyr); means for acquiring values ​​of the magnetometer (MG1, MG2, MG3), the accelerometer (AccX, AccY, AccZ) and the gyroscope (GyrX, GyrY, GyrZ) within a predetermined duration (Δt); and means for UHF (BLE) transmission of said values ​​thus acquired.

11. A motor vehicle (V), characterized in that The motor vehicle comprises an activation device (D) as claimed in any one of claims 4 to 7 .

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