Method for activating a vehicle function and associated activation device

Abstract

The invention relates to a method for starting a motor vehicle (V) by means of an activation device (D) from a portable device (SD) carried by a user, comprising the following steps: a) detecting the locking of an opening element of the vehicle, b) transmitting ultra-wideband waves into the passenger compartment, c) receiving these waves, and for each transmitter module (EM1, EM2, EM3, EM4, EM5, EM6, EM6, EM6, EM6, EM6, EM7, EM6, EM7, EM6, EM7, EM6, EM7, EM6, EM7, EM6, EM7, eM2) performs the following operations: i) comparing a time-of-flight value (TOF) with a predetermined time-of-flight value (TOF d), ii) determining the presence of the portable device within the passenger compartment from the result of the comparison, iii) if the portable device is located within the passenger compartment iv) activating the vehicle function, and v) comparing a received power value (RSSI) with a predetermined received power value (RSSId), vi) determining the presence of the portable device in the passenger compartment from the result of the comparison: 1) if the portable device is not detected in the passenger compartment, calculating a correction value ([delta] RSSI) between the received power and the predetermined received power, 2) the activation device storing said correction value associated with an identifier of the device, for subsequent detection of the presence of the device in the passenger compartment.

Description

[Technical field]

[0001] The invention relates to a method for activating a function of a motor vehicle and to an associated activation device. The invention is particularly, but in no way restrictive, applicable to a "hands-free" start function of a vehicle. [Background Technology]

[0002] In motor vehicles, it is known to use vehicle function activation devices that allow the vehicle to be started "hands-free". For example, detecting the presence of an activation device in the passenger compartment allows the vehicle to be started "hands-free".

[0003] A "hands-free" access system for a motor vehicle enables an authorized user to lock and / or unlock the opening elements of his vehicle without having to physically press a button on the key, or to open the vehicle without having to insert a physical key into the For this purpose, the vehicle recognizes a portable device such as a key fob or remote control or even a key carried by the user, and if the key fob or 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 or starts according to the user's intention, without the user physically manipulating the key.

[0004] To achieve this, 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 vehicle function activation device in order to authenticate the access device by means of its identifier.

[0005] To this end, the activation device comprises at least one radio frequency antenna making it possible to receive the 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 the prior art, the access device is typically an electronic key fob. The signal received by the antenna of the activation device (which includes an identifier of the access device) 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 the electronic control unit) from the vehicle (more commonly referred to as RSSI (received signal strength indication) measurement value), the position of the portable device around the vehicle or in the passenger compartment can be accurately determined. The activation device installed in the vehicle V receives and analyzes the measurement value of the power of each signal received by the portable device from each of the multiple RF antennas located on the vehicle, thereby determining the position of the portable device relative to the RF antenna (i.e. relative to the vehicle) by triangulation.

[0007] Depending on the location of the portable device within the location area identified by the vehicle, certain actions specific to the location area are automatically performed: unlocking / locking or starting the vehicle.

[0008] However, it is increasingly common to use a mobile phone to perform authentication functions, which makes it possible to avoid the use of dedicated electronic key fobs and thus limit the number of devices. Most mobile phones do not have RF or LF communication means. It is therefore necessary to adapt the vehicle's "hands-free" start and / or access system so that it can also communicate with other devices equipped with other communication standards (e.g. Ultra Wideband, or Bluetooth Low Energy). Ultra-wideband (UWB) is a radio modulation technology based on the emission of pulses of very short duration (usually less than one nanosecond). The bandwidth can therefore reach very large values.

[0009] Bluetooth communications, for its part, communicate at frequencies in the range of approximately 2.4 GHz.

[0010] The disadvantage of using Bluetooth (UHF) is that the positioning of the mobile phone is not precise. Bluetooth is subject to a lot of interference, which makes the positioning imprecise. In addition, the positioning of the mobile phone varies significantly from phone to phone.

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

[0012] However, a major drawback of using the received power of waves transmitted via ultra-wideband is that the received power values ​​between mobile phones available on the market are widely dispersed. This high variability in the received power values ​​can result in activating the device when the mobile phone is outside the vehicle while locating the mobile phone inside the vehicle, or vice versa.

[0013] This poses obvious safety issues in terms of authorizing the start of the vehicle.

[0014] A known solution of the prior art is to use the time of flight of the waves to locate the mobile phone. Unfortunately, the time of flight is not a reliable parameter because it is affected by multiple reflections of the waves in the passenger compartment of the vehicle, or by obstacles, thus creating blind areas where the time of flight cannot be used reliably.

[0015] The invention therefore proposes a method for activating a vehicle function, which is starting the vehicle, and an associated activation device which makes it possible to alleviate the disadvantages of the prior art, that is to say to allow precise and reliable positioning of a “hands-free” access device inside the vehicle. [Summary of the invention]

[0016] The present invention relates to a method for activating a function of a motor vehicle from a portable "hands-free" access device carried by a user, the activation of which is triggered by detecting the presence of the user in a predetermined area relative to the vehicle and according to the result of the vehicle's authentication of the "hands-free" access device, the activation device comprising at least two ultra-wideband transceiver modules capable of ultra-wideband communication with the device in the predetermined area, wherein the internal module is located in the passenger compartment of the vehicle, the method comprising the following steps:

[0017] a. Detecting the locking of the opening element of the vehicle,

[0018] b. transmitting ultra-wideband waves into the predetermined area,

[0019] c. Receive the waves from the access device and perform the following operations for each module:

[0020] i. calculating the flight time values ​​of the waves thus received and comparing them with predetermined flight time values,

[0021] ii. determining the presence of the portable device in the predetermined area according to the result of the comparison,

[0022] iii. If the portable device is within the area, then

[0023] 1. Activate the vehicle function, and

[0024] 2. measure the received power values ​​of these waves and compare them with the predetermined received power values,

[0025] 3. Determine the presence of the portable device in the area according to the comparison result:

[0026] a. If the portable device is not detected in the area, then calculating the correction value between the received power and the predetermined received power,

[0027] b. The activation device stores the correction value associated with the identifier of the device for subsequent detection of the presence of the device in the area.

[0028] Advantageously, these predetermined received power values ​​are associated with predetermined time of flight values ​​and the received power is compared with these predetermined received powers as a function of the previously calculated time of flight.

[0029] Advantageously, the predetermined received power values ​​and the predetermined time of flight values ​​are measured during an early stage of calibration using a reference portable device located within the predetermined area.

[0030] The invention also relates to a device for activating a function of a motor vehicle from a portable "hands-free" access device carried by a user, the activation of which is triggered by detecting the presence of the user in a predetermined area relative to the vehicle and based on the result of the vehicle's authentication of the "hands-free" access device, the activation device comprising at least two ultra-wideband transceiver modules capable of ultra-wideband communication with the device within said area, wherein the internal module is located in the passenger compartment of the vehicle, the device (D) further comprising

[0031] a. a device for detecting the locking of the opening element,

[0032] b. means for transmitting ultra-wideband waves into said area and receiving these waves from the device,

[0033] c. means for calculating the time-of-flight values ​​of these waves and comparing them with predetermined time-of-flight values,

[0034] d. means for determining the presence of the portable device in the area based on the result of the comparison,

[0035] e. means for activating a function of the vehicle in response to detection of the device being within the area,

[0036] f. means for measuring the received power values ​​of these waves and comparing them with predetermined received power values,

[0037] g. means for determining the presence of the portable device in the area based on the result of the comparison,

[0038] h. means for calculating a correction value between the received power and the predetermined received power, i. means for storing the correction value associated with an identifier of the device.

[0039] Advantageously, these predetermined received power values ​​are associated with predetermined time of flight values ​​and the means for comparing the received power with the predetermined received power performs the comparison based on a previously calculated time of flight.

[0040] These predetermined received power values ​​and these predetermined time of flight values ​​are determined during an early stage of calibration using a reference portable device located within the area.

[0041] The invention also relates to a computer program product comprising program code instructions for performing the steps of the method according to any of the above listed features, when said program is executed on a computer.

[0042] And finally, the invention is applicable to any motor vehicle comprising an activation device according to any of the features listed above. [Drawings]

[0043] Other features and advantages of the present invention will become more clearly apparent upon reading the following description. This description is purely illustrative and should be read with reference to the accompanying drawings, in which:

[0044] [ Figure 1 ]: Figure 1 is a schematic depiction of a vehicle equipped with an activation device according to the invention,

[0045] [ Figure 2 ]: Figure 2 is a schematic depiction of an activation device according to the invention,

[0046] [ Figure 3 ]: Figure 3 is a flow chart illustrating an activation method according to the present invention. [Specific implementation method]

[0047] Figure 1 A motor vehicle V is depicted equipped with an activation device D according to the invention. The activation device D comprises at least two ultra-wideband (UWB) transceiver antenna modules EM1, EM2 capable of ultra-wideband communication with a portable access device SD carried by a user U within zones Z0, Z1, Z2 defined relative to the vehicle V, at least one internal module EM1 of which is capable of communicating with the device when the device is located within an internal zone Z0 of the vehicle interior.

[0048] The activation device D further comprises a central control unit 10 which is electrically connected to the two UWB modules EM1 , EM2 .

[0049] The central control unit 10 makes it possible to manage the transmission and reception of UWB data via these modules. This is known in the prior art and will not be described in more detail here.

[0050] Ultra-wideband (UWB) communication is a type of radio frequency communication based on the emission of pulses of very short duration (usually less than one nanosecond). As a result, the bandwidth can reach very large values ​​between 250 and 500 MHz.

[0051] As described above, in this case, using the power value RSSI (Received Signal Strength Indication) received by the device and transmitted to the antenna modules EM1, EM2 to determine the position of the access device SD in the passenger compartment of the vehicle V is inaccurate and unreliable, because the received power value varies greatly between different access devices.

[0052] The present invention proposes an activation method and a device making it possible to remedy this disadvantage and to enable reliable and precise positioning inside the vehicle V.

[0053] For this purpose, the activation device D according to the invention comprises:

[0054] a. a device M1 for detecting the locking of the opening element,

[0055] b. means M2 for transmitting ultra-wideband waves into the vehicle V and receiving waves from the device SD,

[0056] c. means M3 for calculating the time-of-flight value TOF of the wave thus received and comparing it with a predetermined time-of-flight value TOFd,

[0057] d. means M4 for determining the presence of the portable device SD in the vehicle V according to the result of the comparison,

[0058] e. means M5 for activating a vehicle function in response to detection of the device SD in the vehicle V,

[0059] f means for measuring the received power value RSSI of the wave and comparing it with a predetermined received power value RSSId M6,

[0060] g. means M7 for determining the presence of the portable device SD in the vehicle according to the result of the comparison,

[0061] h. means M8 for calculating a correction value ΔRSSI between the received power RSSI and the predetermined received power RSSId,

[0062] i. Means M9 for storing said correction value ΔRSSI associated with the identifier ID of the device SD.

[0063] The detection means M1, the transmission means M2, the calculation and comparison means M3, the determination means M4, the means for activating the function M5, the comparison means M6, the determination means M7, the increment or decrement means M8 and the storage means M9 are preferably implemented in a manner which is contained in the central control unit 10 (see Figure 2 ) in the form of software in an integrated circuit.

[0064] The central control unit 10 also includes a processor 100 and a memory 101 (see Figure 2 ), in which instructions are stored, the processor is configured to perform certain specific processing operations, in particular, to implement the steps of the activation method according to the embodiments described below.

[0065] The means M1 for detecting opening elements make it possible to detect that all opening elements of the vehicle are closed before the triggering modules EM1 , EM2 emit UWB waves.

[0066] The means M2 for emitting UWB waves into the vehicle V and receiving waves from the portable access device SD are known to those skilled in the art and are not described in detail here. It is important to note that according to the invention, the two modules EM1, EM2 are able to emit waves that propagate through the interior zone Z0 of the vehicle V, ie the passenger compartment, once the opening element has been closed.

[0067] The means M3 for calculating the time of flight determine the time of flight TOF of these waves between emission by the modules EM1, EM2 and reception by these modules; the time of flight TOF therefore makes it possible to calculate the distance d separating each module EM1, EM2 from the portable access device SD; in particular, the time of flight TOF is directly related to said distance d by the propagation speed of the waves, i.e. the speed of light. This is known in the prior art.

[0068] By comparing the time of flight TOF with predetermined time of flight values ​​TOFd (these predetermined time of flight values ​​were previously measured with an access device SD located in the passenger compartment) for each module EM1, EM2, it is thus possible to know whether the portable device SD is located in the passenger compartment or outside the vehicle V. Preferably, but not restrictively, in a good embodiment of the invention, the interior module EM1 is located in a central position in the passenger compartment. The determination means M4 therefore make it possible to infer whether the portable device SD is present in the passenger compartment.

[0069] If, after comparing the time of flight TOF with TOFd, the device SD is detected in the passenger compartment Z0 , the device M5 for activating the vehicle function triggers the start of the vehicle.

[0070] Similarly, according to the present invention, it is recommended that for each module EM1, EM2, the received power RSSI of the access device SD when receiving the wave emitted from the module EM1, EM2 is measured with the help of the measuring and comparing device M6, and, for each module EM1, EM2, the power measurement value RSSI is compared with the predetermined received power value RSSId.

[0071] Said predetermined received power value RSSId is previously measured during a calibration phase with the aid of a reference portable device SD0 located in the passenger compartment, which has, for example, the characteristic of maximum received power, i.e. maximum radio frequency power; other portable devices have lower power and are poorly positioned, which makes it possible to avoid false detections outside the vehicle V. Preferably, during this calibration phase, for each position of the reference access device SD0 in the passenger compartment, for each module EM1, EM2, the time of flight TOFd and the received power RSSId are measured. Thus, the received power and time of flight value pair (RSSId, TOFd) of each module EM1, EM2 makes it possible to accurately locate the access device SD in the passenger compartment.

[0072] According to the invention, the received power RSSI is compared with a predetermined received power value RSSId corresponding to the time of flight TOF of a previously measured pair of values ​​RSSId, TOFd.

[0073] Like the time of flight TOF, the received power RSSI is an indicator that makes it possible to know whether the access device SD is inside the passenger cabin. The received power RSSI is also related to the distance d between each internal module EM1, EM2 of the access device SD and the internal configuration of the passenger cabin (the presence of obstacles, etc.).

[0074] However, since the received power RSSI has non-negligible variations between different portable devices, this indicator itself is unreliable.

[0075] In the case where the received power RSSI from the access device SD corresponds to the predetermined value RSSId (in other words, corresponds to the predetermined value of the reference portable device SD0), the result of the comparison is that the received power difference ΔRSSI between the two values ​​is equal to zero, and the determination means M7 concludes that the portable device SD is inside the passenger compartment Z0. In this case, the received power characteristics of the portable device correspond to the received power characteristics of the reference portable device SD0.

[0076] In contrast, if the received power RSSI from the portable device SD is different from the predetermined value RSSId from the reference device SD0, for example, if the value RSSI is higher or lower than the predetermined value RSSId, the comparison is unlikely to lead to the conclusion that the access device SD is in the passenger compartment. The received power characteristics of the portable device SD are then different from the received power characteristics of the reference portable device SD0.

[0077] In this case, according to the present invention, the device M8 for calculating the correction value ΔRSSI increases or decreases the received power value RSSI from the portable device SD so that the difference between the two values ​​is equal to zero, that is, the device M8 compensates the received power value RSSI from the access device SD so as to make it equal to the predetermined value RSSId from the reference access device SD0.

[0078] Once these two values ​​are equal, i.e. RSSI=RSSId, the storage means M9 stores the correction value ΔRSSI=RSSI-RSSId (that is, incrementing or decrementing as necessary) in, for example, the memory 101 of the central unit 10, thereby associating it with the identifier ID of the access device SD (which identifier has already been exchanged during a previous ultra-wideband communication).

[0079] Once the correction value ΔRSSI has been stored, it will be automatically applied during future communications between the activating device D (whether transceiver module EM1 or EM2) and the accessing device SD (once identified by means of its identifier ID) in order to subsequently locate said device SD precisely inside the passenger compartment Z0. The correction value ΔRSSI is then applied to all received power values ​​RSSI from said device SD.

[0080] We will now describe Figure 3 The activation method shown in .

[0081] In an earlier step E0 , it was checked that all open elements of the vehicle V were closed.

[0082] Then, in a first step E1 , the modules EM1 , EM2 transmit waves into the passenger compartment of the vehicle V. The waves are received by an access device SD located inside the vehicle V and then sent by said device SD to said modules EM1 , EM2 .

[0083] Next, during a second step E2 , these waves are received by the activation device D via the modules EM1 , EM2 .

[0084] Then, during a third step E3 , the return time of flight TOF of these waves is calculated for each module EM1 , EM2 .

[0085] During a fourth step E4 , it is determined whether the access device SD is located inside the vehicle V by comparing, for each module, the flight time TOF thus measured with flight time values ​​TOFd predetermined during an earlier calibration phase, wherein these predetermined flight time values ​​represent a reference access device SD0 located in the passenger compartment.

[0086] In particular, during this earlier calibration phase, the position of the access device SD0 inside the passenger compartment is associated with each pair of predetermined time-of-flight values ​​TOFd and received power values ​​RSSId. The time-of-flight is an accurate indicator of the location of the access device SD; however, it is affected by reflections and attenuation and is not sufficient by itself to determine the location of the access device SD within the entire interior zone Z0. Similarly, the received power RSSI is not sufficient by itself to locate a portable device. However, the Applicant has observed that by associating these two parameters RSSI, TOF, the accuracy and reliability of the location can be significantly improved.

[0087] If the access device SD is located in the passenger compartment Z0 , the function of the vehicle V is activated (step E5 ), here by starting the vehicle V, and according to the invention, in contrast to the prior art, the activation method continues as follows.

[0088] In a sixth step E6 , the received power RSSI of the portable device SD is measured for each module EM1 , EM2 and compared with a predetermined received power value RSSId corresponding to the previously determined time of flight TOF.

[0089] During a seventh step E7 , if the received power value corresponds to a predetermined received power value RSSId, the determination means M7 conclude that the access device SD is inside the passenger compartment Z0 and then activate the vehicle function (step E11 ).

[0090] If the received power value RSSI does not correspond to the predetermined received power value RSSId, the calculation means M8 determine a correction value ΔRSSI for each module EM1, EM2 (step E8), which may be an increment or decrement of the received power RSSI so that it is equal to the predetermined received power value RSSId. Of course, this increment or decrement can be performed step by step in steps of +1 dB or -1 dB. This step is repeated until the received power value RSSI is equal to the predetermined received power value RSSId (step E9). The difference ΔRSSI between the measured received power RSSI and the predetermined received power RSSId is different between the two modules EM1, EM2. Therefore, the modules EM1, EM2 can be corrected differently and each module has a specific correction value ΔRSSI.

[0091] When these two values ​​are equal (step E9 ), ie RSSI=RSSId, during a tenth step E10 , the storage means M9 of the activated device D store in its memory the correction value ΔRSSI of each module EM1 , EM2 (associated with the identifier ID of the portable device SD).

[0092] Therefore, for all future communications between the activating device D and the identified portable device SD, the activating device D will correct all received power values ​​RSSI by applying the correction value ΔRSSI specific to each module EM1 , EM2 .

[0093] The invention is particularly ingenious in that it is easy to implement and transparent to the user, making it possible to reliably and robustly locate an access device in the passenger compartment of a vehicle, thereby ensuring the safety of the vehicle's start function.

Claims

1. A method for activating a function of a motor vehicle (V) from a portable "hands-free" access device (SD) carried by a user (U), the activation of which is triggered by detecting the presence of the user (U) in a predetermined zone (Z0) relative to the vehicle (V) and according to the result of the authentication of the "hands-free" access device (SD) by the vehicle (V), the activation device comprising at least two ultra-wideband (UWB) transceiver modules (EM1, EM2) capable of ultra-wideband communication with the device in the predetermined zone, the internal module (EM1) being located in the passenger compartment of the vehicle, wherein The method comprises the following steps: a) detecting the locking of an opening element of the vehicle (V), b) transmitting ultra-wideband waves into the predetermined area (Z0), c) Receive the waves from the access device (SD) and perform the following operations for each module (EM1, EM2): i) calculating the time of flight value (TOF) of the waves thus received and comparing it with a predetermined time of flight value (TOFd), ii) determining the presence of the portable device (SD) within the predetermined area (Z0) according to the result of the comparison, iii) if the portable device (SD) is located within said zone (Z0), then 1) Activate the vehicle function, and 2) measuring the received power values ​​of these waves (RSSI) and comparing them with a predetermined received power value (RSSId), 3) Determine the presence of the portable device in the zone (Z0) according to the result of the comparison: a. If the portable device (SD) is not detected in the zone (Z0), a correction value (ΔRSSI) is calculated between the received power (RSSI) and the predetermined received power (RSSId), b. the activation device stores said correction value (ΔRSSI) associated with an identifier (ID) of the device (SD) for subsequent detection of the presence of the device in said zone (Z0), c. applying said correction value (ΔRSSI) to all these received power values ​​(RSSI) from said device (SD), d. localizing the device (SD) in the passenger compartment (Z0) on the basis of the received power corrected in this way.

2. The activation method according to the preceding claim, wherein: These predetermined received power values ​​(RSSId) are associated with predetermined time of flight values ​​(TOFd), and wherein the received power (RSSI) is compared with the predetermined received power (RSSId) based on a previously calculated time of flight (TOF) corresponding to the predetermined time of flight (TOFd).

3. The activation method according to any one of the preceding claims, wherein: The predetermined received power values ​​(RSSI) and the predetermined time of flight values ​​(TOFd) are measured during an early stage of calibration using a reference portable device (SD0) located within the predetermined zone (Z0).

4. A device (D) for activating a function of a motor vehicle from a portable "hands-free" access device (SD) carried by a user (U), the activation of which is triggered by detecting the presence of the user (U) in a predetermined zone (Z0) relative to the vehicle (V) and according to the result of the authentication of the "hands-free" access device (SD) by the vehicle (V), the activation device comprising at least two ultra-wideband (UWB) transceiver modules (EM1, EM2) capable of ultra-wideband communication with the device in said zone, wherein the internal module (EM1) is located in the passenger compartment of the vehicle (V), wherein The device (D) further comprises a) a device (M1) for detecting the locking of the opening element, b) means (M2) for emitting ultra-wideband waves into said zone (Z0) and receiving these waves from the device (SD), c) means (M3) for calculating the time of flight value (TOF) of these waves and comparing it with a predetermined time of flight value (TOFd), d) means (M4) for determining the presence of the portable device (SD) within the zone (Z0) based on the result of the comparison with a predetermined time-of-flight value, e) means (M5) for activating the vehicle function in response to detecting that the device is within the zone (Z0), f) means (M6) for measuring the received power value (RSSI) of these waves and comparing it with a predetermined received power value (RSSId), g) means (M7) for determining the presence of the portable device (SD) within the zone (Z0) based on the result of the comparison with a predetermined received power value, h) means (M8) for calculating a correction value (ΔRSSI) between the received power (RSSI) and the predetermined received power (RSSId), i) means (M9) for storing said correction value (ΔRSSI) associated with an identifier (ID) of the device (SD).

5. Activation device (D) according to the preceding claim, wherein These predetermined received power values ​​(RSSId) are associated with predetermined flight time values ​​(TOFd), and wherein the device (M6) for comparing the received power (RSSI) with the predetermined received power (RSSId) performs the comparison based on a previously calculated flight time (TOF) corresponding to the predetermined flight time (TOFd).

6. An activation device (D) as claimed in claim 4 or 5, wherein: The device further comprises a received power value (RSSId) and a time of flight value (TOFd) which are predetermined during an early stage of calibration using a reference portable device (SD0) located within the zone (Z0).

7. A computer program product comprising program code instructions for executing the steps of the method as claimed in any one of claims 1 to 3 when said program is executed on a computer.

8. A motor vehicle (V), wherein: The motor vehicle comprises an activation device (D) as claimed in any one of claims 4 to 6.

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