Vehicle function activation method using portable user equipment through ultra-wideband and related function activation system and device

Abstract

The present invention relates to an activation method for activating a vehicle (V) function by means of a portable user device (P), wherein the portable user device (P) performs ultra-wideband communication with an activation device (D) carried in the vehicle, and the vehicle function is activated according to the position of the portable device relative to the boundary (F) between an inner zone (Z2) and an outer zone (Z1) of the vehicle, the activation method comprising the following steps: a) pre-equipping the vehicle with an inner antenna (A2) and an outer antenna (A1), b) determining the presence of the portable device in an authorized zone around the vehicle, c) storing a power delay (PDP) of a multipath ultra-wideband signal received by each antenna according to time, d) determining a decay period (I, I′, I″, I″′) of the received power for each antenna and for a power threshold (T), e) comparing the decay period (I, I′, I″, I″′) with at least one reference period (Iref), f) determining, according to the result of the comparison, whether the portable device is located in the inner zone or the outer zone, and g) activating the vehicle function corresponding to the position of the portable device.

Description

Technical Field

[0001] The present invention relates to a function activation method for activating a function of a motor vehicle by using a portable user device via ultra wide band (ULB, or "ultra wide band" in English, UWB) and a related function activation system and device.

[0002] The invention applies more particularly to "hands-free" entry and / or starting systems for motor vehicles. So-called "hands-free" entry systems for motor vehicles enable an authorized user to lock and / or unlock the opening of his vehicle or to start the vehicle without using a key. To this end, the vehicle identifies a portable device carried by the user, such as a badge or a remote control, and if the badge or remote control is located in a predetermined area around or in the vehicle and is identified as belonging to the vehicle, the vehicle automatically locks / unlocks its opening or starts according to the user's intention, without the user having to use a key. Background Art

[0003] Such "hands-free" entry systems are known to those skilled in the art and typically consist of an electronic control unit carried in the vehicle, one or more radio frequency (RF) antennas located on the vehicle, and an identification remote control or badge carried by the user that includes an RF antenna.

[0004] The exchange of identifiers between the portable device and the vehicle via the RF antenna and the electronic control unit enables the vehicle to identify the portable device and trigger the locking or unlocking of the opening member or the starting of the vehicle.

[0005] Instead of being contained in a badge or remote control, the identifier may be contained in a portable device, for example it may be contained in a mobile phone or "smartphone" or a watch carried by the user.

[0006] The identifier exchange is usually carried out through radio frequency (RF) waves and low frequency (LF, English for "Low Frequency") waves. The vehicle first transmits an LF polling signal through the LF antenna, and if the portable device is located in the reception area of ​​the signal (i.e., a predetermined area around the vehicle), an RF presence message containing its identifier is returned to the vehicle.

[0007] The portable device is accurately located around the vehicle by measuring the strength of the LF signal received by the portable device (via the antenna and the electronic control unit) from the vehicle (commonly referred to as RSSI ("Received Signal Strength Indication" or a measurement of the received power of the signal received by the antenna). The positioning device on board the vehicle receives and analyzes the power measurements of the signal received by the portable device from each LF antenna to determine the position of the portable device relative to the LF antenna, i.e., relative to the vehicle.

[0008] Based on the location of the portable device identified by the vehicle, certain actions specific to the location area are automatically performed in the location area, such as starting the vehicle, unlocking / locking, or pre-activating interior lighting (also called guide lighting).

[0009] RSSI measurements enable accurate localization of the portable device in the localization area, ie around and inside the vehicle, so that when the portable device is detected inside the vehicle not only the opening means can be locked / unlocked but also the vehicle can be started.

[0010] In the case where the portable device is a mobile phone, communication with the vehicle at RF (e.g., in the ISM band) and LF (e.g., at 125 kHz) is not always possible because most mobile phones do not have RF or LF communication means with frequencies compatible with the frequencies used when communicating with the vehicle, such as 315 MHz and 433.92 MHz for RF and 125 kHz for LF.

[0011] In contrast, mobile phones now have Or the Bluetooth Low Energy "BLE" communication standard, i.e. Ultra High Frequency (UHF) communication from 2402MHz to 2480MHz, or the Ultra Wideband communication standard (or "UWB" in English), i.e. a short-range wireless communication protocol (IEEE 802.15.4a standard) that enables the use of a very wide frequency band. Like Bluetooth and Wi-Fi, this communication protocol uses radio waves, but at very high frequencies, it includes 14 communication channels, each with a bandwidth equal to 500MHz, in a frequency range from 3.1GHz to 10.6GHz. A UWB transmitter can send a pulse every two nanoseconds.

[0012] Communication standards such as BLE, Bluetooth or UWB have the advantage of being universal and therefore do not require licensing specific to each country as is currently the case for RF and LF communication standards (only "Bluetooth Low Energy" or "UWB" international certification is required), the operating frequencies of which vary from country to country.

[0013] Therefore, it is necessary to adapt the vehicle's "hands-free" entry and / or starting system so that it can also be used with a vehicle equipped with a Or UWB communication standards with mobile phones, rather than just operating via radio waves and low-frequency waves (RF, LF).

[0014] The advantage of the communication standard is that it enables a large communication range of about 250 meters around the vehicle. However, it cannot accurately detect the presence of a portable device at a shorter distance. For example, when the portable device is inside a vehicle and the user wishes to start his vehicle, the accurate positioning of the portable device that can be achieved by the prior art communication device operating by exchanging RF and LF waves is not enough. No longer possible. In fact, RSSI measurements of Bluetooth signals are very inaccurate and vary greatly depending on the environment (noise, interference, etc.), and there is no way to know if a fixed-position portable device is 5m, 10m, 40m or more away from the vehicle.

[0015] Therefore, it is no longer possible to use communication to activate functions such as starting the vehicle, since starting must only be authorized when the portable device is inside the vehicle and a few centimeters away from the vehicle's UHF antenna. Due to the large changes in RSSI, it is impossible to detect the portable device a few centimeters away from the UHF antenna.

[0016] As for the UWB communication standard, it enables more accurate positioning than the Bluetooth standard and consumes less energy. It is known in the prior art to use the UWB signal power by transmitting short pulses in order to measure the distance between a portable device and a vehicle.

[0017] One solution of the prior art consists in using the time of flight, which enables the propagation time of the waves to be estimated and hence the distance between the portable device and the vehicle to be deduced.

[0018] However, this solution has several disadvantages:

[0019] a. Due to multiple reflections on the metal parts of the vehicle, UWB signals are usually transmitted to one or more receivers (antennas) in the vehicle via several propagation paths. Therefore, the signal arrives with a delay related to the length of the propagation path. These delays can cause significant errors in the positioning of portable devices.

[0020] b. The flight time is calculated between the portable device and at least three receivers (antennas) visible to the portable device. If the portable device is located on one side of the vehicle, the communication with one or more antennas located on the other side of the vehicle (i.e. not "visible" to the portable device) is interrupted, and the flight time calculation cannot be performed.

[0021] c. UWB signals are sensitive to the orientation of the portable device and its position relative to the user's body. This sensitivity can affect the calculation of the flight time and produce errors in the positioning of the portable device.

[0022] d. The diversity of portable devices in terms of antenna type and location, transmit power and receive sensitivity will also affect the calculation of flight time.

[0023] e. Finally, to partially overcome the above disadvantages, a positioning method using time of flight would require eight antennas on the vehicle, four located outside the vehicle and four located inside the vehicle, which means a non-negligible excess cost.

[0024] The present invention proposes a vehicle function activation method and a related function activation device using a portable user device through ultra-wideband communication, which enable these disadvantages to be overcome.

[0025] Specifically, the present invention proposes a function activation method through ultra-wideband waves that enables accurate positioning of a portable user device inside or outside a vehicle. Summary of the invention

[0026] The present invention proposes a method for activating a vehicle function by ultra-wideband communication through a portable user device, wherein the portable user device performs ultra-wideband communication with an activation device carried in the vehicle, and the vehicle function is activated according to the position of the portable device relative to the boundary between the inner area and the outer area of ​​the vehicle, and the activation method is characterized in that it comprises the following steps:

[0027] a. Equip the vehicle with internal and external antennas in advance,

[0028] b. determining the presence of a portable device in an authorized area around the vehicle,

[0029] c. storing the power delay of the multipath UWB signal received by each antenna according to time,

[0030] d. determining a decay period of the received power for each antenna and for a power threshold,

[0031] e. comparing the decay period to at least one reference period,

[0032] f. determining whether the portable device is located in an inner area or an outer area according to the result of the comparison,

[0033] g. Activate a vehicle function corresponding to the location of the portable device.

[0034] Ingeniously, the reference period is predetermined as a function of the received signal power for each antenna when the portable device is located on the boundary between the interior area and the exterior area of ​​the vehicle.

[0035] Advantageously, decay periods are determined for several power thresholds and compared with several corresponding reference periods.

[0036] The vehicle function includes unlocking a vehicle's opening feature when the portable device is in an exterior area.

[0037] The vehicle function includes starting the vehicle when the portable device is within an interior area of ​​the vehicle.

[0038] The invention also relates to a device for activating vehicle functions by ultra-wideband, intended to be carried in a vehicle and to communicate with a portable user device by ultra-wideband, activating vehicle functions according to the position of the portable device relative to the boundary between the interior area and the exterior area of ​​the vehicle, said device comprising an electronic management unit controlling the activation of the functions, characterised in that it comprises:

[0039] a. Internal antenna,

[0040] b. External antenna,

[0041] c. a determination means for determining the presence of a portable device in an unlocking zone around the vehicle,

[0042] d. an analysis and processing component for analyzing and processing a multipath ultra-wideband signal received by the antenna, adapted to:

[0043] i. storing the power delay of the multipath UWB signal received by each antenna according to time,

[0044] ii determining a decay period for each antenna and for a power threshold,

[0045] iii. comparing the decay period to at least one reference period,

[0046] iv. determining whether the portable device is located in the inner area or the outer area according to the result of the comparison,

[0047] v. Activate a vehicle function corresponding to the location of the portable device.

[0048] In a first embodiment of the invention, the analysis and processing means are comprised in a transceiver module of the vehicle.

[0049] The invention also applies to a vehicle function activation system comprising an activation device according to any of the features listed above and a portable user device, the system being characterized in that the analysis and processing means are also comprised in the portable device.

[0050] In a second embodiment of the present invention:

[0051] a. The device comprises an electronic management unit controlling activation of the function, an internal antenna, an external antenna, at least one transceiver module connected to the antenna, a determination component for determining the presence of a portable device in an unlocking zone around the vehicle,

[0052] b. and the portable device comprises an analysis and processing component for analyzing and processing the multipath ultra-wideband signal received by the antenna, which is adapted to:

[0053] i. storing the power delay of the multipath UWB signal received by each antenna according to time,

[0054] ii. determining a decay period for each antenna and for at least one power threshold,

[0055] iii. comparing the decay period to at least one reference period,

[0056] iv. determining whether the portable device is located in the inner area or the outer area according to the result of the comparison,

[0057] v. Activate a vehicle function corresponding to the location of the portable device.

[0058] Finally, the invention relates to any motor vehicle comprising an activation device according to any of the features listed above. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Other features and advantages of the present invention will become more apparent from the following description. This description is purely illustrative and should be read with reference to the accompanying drawings, in which:

[0060] Figure 1 A vehicle equipped with a vehicle function activation device according to the present invention is schematically shown,

[0061] Figure 2 is a flow chart showing a vehicle function activation method according to the present invention,

[0062] Figure 3a is a graph showing the normalized power variation over time of a multipath signal received by an external UWB antenna when the portable device P is located outside a vehicle V,

[0063] Figure 3b is a graph showing the normalized power variation over time of a multipath signal received by an internal UWB antenna when a portable device P is located outside a vehicle V,

[0064] Figure 3cis a graph showing the normalized power variation over time of a multipath signal received by an external UWB antenna when the portable device P is located inside a vehicle V,

[0065] Figure 3d is a graph showing the normalized power variation over time of a multipath signal received by an internal UWB antenna when a portable device P is located inside a vehicle V,

[0066] Figure 4a schematically illustrates multiple propagation paths of a UWB signal transmitted by a portable device when the portable device is located outside a vehicle,

[0067] Figure 4b schematically illustrates multiple propagation paths of a UWB signal transmitted by a portable device when the portable device is located inside a vehicle,

[0068] Figure 5a schematically illustrates the delimitation between an inner area and an outer area for positioning a portable device relative to a vehicle,

[0069] Figure 5b is a graph showing a reference attenuation period Iref as a function of normalized power of a received multipath signal by placing the portable device at a boundary F between the inner area and the outer area. DETAILED DESCRIPTION

[0070] According to the present invention, Figure 1 A motor vehicle V is schematically shown, which is equipped with a vehicle function activation device D for activating a vehicle function, the vehicle function activation device D being able to communicate with a portable user device P via UWB communication and being able to accurately locate the portable device around the vehicle V via UWB communication, the device D comprising:

[0071] a. A first module ER1 for UWB signal transceiver connected to an external UWB antenna A1,

[0072] b. A second module ER2 for UWB signal transceiver connected to the internal UWB antenna A2,

[0073] c. An electronic management unit, also called "BCM", body control unit or body management unit, which is electrically connected to the first and second modules.

[0074] The first module ER1 and the second module ER2 are equipped with software components or electronic components that enable the transmission and reception of UWB signals by means of the external antenna A1 and the internal antenna A2, respectively. The first and second modules can be combined into a single module and form a unique single module including software components and / or electronic components, which enable the transmission and reception of UWB signals by means of two antennas A1 and A2, and control the transmission and reception of the two antennas A1 and A2. Each antenna can be connected to a dedicated transceiver circuit so that the two antennas A1 and A2 can transmit and receive UWB signals in parallel, or alternatively, a single transceiver circuit can be connected to the two antennas A1 and A2 for the two antennas to transmit and receive UWB signals, and the transmission and reception of the two antennas are then operated in a sequential mode. In the latter configuration, the transceiver circuit switches from one antenna A1, A2 to another antenna A1, A2 at a fixed frequency. This is known to those skilled in the art.

[0075] Internal and external antennas are radio frequency antennas that enable the transmission and reception of UWB signals, i.e. in the frequency range between 3 GHz and 10 GHz. An internal antenna A2 means that the antenna A2 is located inside the vehicle V (e.g. in the passenger compartment) or is facing the interior of the vehicle V. An external antenna A1 means that the antenna is preferably located in or on the body of the vehicle V, i.e. on an outer surface of the vehicle V or is facing the exterior of the vehicle V.

[0076] As for the first and second modules ER1 , ER2 , they may be located anywhere in the vehicle V.

[0077] As for the electronic management unit BCM, it enables processing of the signals received by the first and second modules ER1 and ER2 and also enables control of the transmission of signals to the portable device P by means of said first and second modules and the associated external and internal antennas A1 , A2 .

[0078] The device D also comprises an analysis and processing unit M1 for analyzing and processing the signals received by the two antennas A1, A2 (see Figure 1 ), which enables the positioning of the portable device P relative to the vehicle to be determined, and if the portable device P is located outside the vehicle V, it controls unlocking the vehicle door, and if the portable device P is located inside the vehicle V, it controls starting the engine of the vehicle V.

[0079] Said analysis and processing means M1 may be comprised in the vehicle V, for example in the electronic management unit BCM, or in the first and second modules ER1, ER2, or in the portable device P, or in both. Said means M1 is connected to unlocking control means and / or starting means of the vehicle V, which are usually situated in the electronic management unit BCM. Said electronic management unit BCM controls the door opening mechanism and / or the starting circuit of the vehicle V.

[0080] The invention is then applicable to a system comprising an activation device D and a portable device P, in the case where the analysis and processing means M1 is also or only located in the portable device P. The presence of the analysis and processing means M1 in the vehicle V and in the portable device P, i.e. the duplication of said means M1, enables redundancy to be provided for information processing and decision making.

[0081] In the case where the analysis and processing means M1 are comprised only in the portable device P, the vehicle actions are controlled only by the phone which will request the door opening mechanism and / or the starting circuit of the vehicle V to unlock or start the vehicle depending on the positioning of the portable device P.

[0082] In this case, the analysis and processing means M1 make it possible to store the decay period of the UWB signals received by the first and second antennas A1, A2 based on a parameter called PDP (“Power Delay Profile”). Said PDP parameter gives the value of the power of the received signals as a function of time, these signals having propagated along several paths, in this case direct paths, but also indirect paths in which the signals are reflected by any metallic surface or the ground of the vehicle V. This is in Figure 4a and 4b Shown in.

[0083] Figure 4a A UWB signal S is shown that is transmitted by a portable device P to a vehicle V when the portable device P is located outside the vehicle V in an exterior zone Z1. The signal S is characterized by multiple propagation paths, including paths reflected by the ground. Only some of these propagation paths enter the vehicle V. When the signal enters the passenger compartment of the vehicle, it is reflected more due to the presence of many metal surfaces.

[0084] Figure 4b The UWB signal S transmitted by the portable device P to the vehicle V is shown when the portable device P is located inside the vehicle V in the interior zone Z2. In this case, the signal is also divided into multiple propagation paths that are reflected on various metal surfaces in the passenger compartment.

[0085] In practice, as will be explained below, by comparing the power decay period (Iref) of the multipath signal received by the external antenna A1 with respect to at least one reference period Iref, Figure 4a ) and the power decay period of the reflected multipath signal received by the internal antenna A2 ( Figure 4b ), it can be determined that the portable device P is located outside the vehicle V ( Figure 1 , 4a , 4b and 5a) or in the interior of the vehicle V ( Figure 1 , 4a, the inner area Z2 in 4b and 5a).

[0086] To this end, as will be described below, the analysis and processing component M1 is adapted to:

[0087] a. Store the power delay PDP of the multipath ultra-wideband signal received by each antenna A1 and A2 according to time,

[0088] b. determining for each antenna A1, A2 and for at least one power threshold T a decay period I, I', I", I'',

[0089] c. comparing the decay periods I, I', I", I'' with at least one reference period Iref,

[0090] d. according to the result of the comparison, determining whether the portable device P is located in the inner zone Z2 or the outer zone Z1,

[0091] e. Activate the vehicle function corresponding to the location of the portable device P.

[0092] An activation device D intended to be mounted in a vehicle V makes it possible to accurately locate the portable user device relative to the vehicle, i.e., in an interior zone Z2 or in an exterior zone Z1 of the vehicle V; so as to activate a function of the vehicle, unlocking the portable device P if it is located in the exterior zone Z1, or starting the vehicle's engine if the portable user device P is located in the interior zone Z2.

[0093] Unlike the prior art which requires at least three associated antennas located on the vehicle V to determine the position of the portable user device P relative to the vehicle V by triangulation, the activation device according to the present invention itself only includes at least two antennas A1 and A2, one antenna A1 is located outside the vehicle V, for example, on the door body on the driver's seat side, and the other antenna A2 is located inside, for example, in the center console between the two front seats.

[0094] The external antenna A1 is preferably (but not restrictively) located on the opening part that is desired to be unlocked, here, in this example, on the front door on the driver's side. The first module ER1 electrically connected to said antenna A1 is then located on or in the vehicle V, its location being unimportant.

[0095] If it is desired to unlock the trunk of the vehicle V, it may be considered to add a third antenna A3 on the trunk outside the vehicle (see Figure 1 ), which antenna is electrically connected to a unique transceiver module already connected to the internal antenna A2 and the external antenna A1, or to an additional module ER3 (not shown) dedicated to the third antenna A3.

[0096] According to one aspect of the invention, at least two antennas are therefore required, one inside and one outside the opening member that is desired to be unlocked (A1, A2).

[0097] Now according to Figure 2 and in Figures 3a to 3d , 4a, 4b, 5a, 5b support the description of a vehicle function activation method according to one aspect of the present invention.

[0098] In an initial step E0, the vehicle V repeatedly transmits UWB signals in order to detect the presence of a portable device P in the UWB transmission area around the vehicle V. This method of transmission is also called "polling", probing or scanning. To this end, the electronic unit BCM controls the transmission of the UWB signals by means of the first module ER1 and the associated external antenna A1.

[0099] In step E1, if the portable device P receives the scanning signal, this means that the portable device P is located in the area for UWB communication with the vehicle V (step E2). The portable device P sends a response signal to the vehicle V, otherwise, if the portable device P does not receive the scanning signal, the scanning method continues (returning to the preliminary step E0).

[0100] The scanning signal received by the portable device P is time-stamped, and similarly, the response signal sent by the portable device P to the vehicle V is also time-stamped.

[0101] When the vehicle V receives the response signal (step E3 ), the vehicle V then sends a confirmation signal to the portable device P again (step E3 ), which confirmation signal is also time-stamped.

[0102] By calculating the flight time of the response signal from the portable device P to the vehicle V (step E4) and the flight time of the confirmation signal from the vehicle V to the portable device P, it is then possible to determine the presence of the portable device P in a predetermined area around the vehicle, which is a fairly close area corresponding to the area of ​​authorized actions on the vehicle V, for example, authorization to unlock or start heating the seats or turn on the lights. This positioning method is a prior art positioning method and is based on the flight time. However, as mentioned above, this method is not accurate and it is not possible to know whether the portable device P is outside or inside the vehicle V.

[0103] In step E5 , it is verified whether the flight time corresponds to the portable device P being located in the unlocking authorization zone or outside said zone.

[0104] It should be noted that verifying the presence of the portable device P in the unlocking authorization zone may be performed by any other method, for example by radio frequency and low frequency communication, by Bluetooth or BLE (“Bluetooth low energy”). Or any communication means making it possible to detect approximately the presence of the portable device P in the unlocking authorization zone around the vehicle V.

[0105] If the portable device P is located in the unlocking authorization zone (step E5), the "PDP" of each module is calculated. More specifically, the power of the signal, or also called "path power" (in dBm), the analysis and processing means M1 of each module - in this case the external module ER1 (step E6) and then the internal module ER2 (step E7) - store, in time, all the multipath signals received by each antenna, which are Figure 3a , 3b , 3c, 3d.

[0106] Figure 3a , 3b , 3c, 3d show the normalized power An of the received multipath signal as a function of the time unit (u) for four examples:

[0107] a. Figure 3a In the example, the portable device P is located outside the vehicle V, and the normalized power An is the power received by the external antenna A1.

[0108] b. Figure 3b In the example, the portable device P is located outside the vehicle V, and the normalized power An′ is the power received by the internal antenna A2.

[0109] c. Figure 3c In the example, the portable device P is located inside the vehicle V, and the normalized power An″ is the power received by the external antenna A1.

[0110] d. in Figure 3d In FIG. 5 , the portable device P is located inside the vehicle V, and the normalized power An″′ is the power received by the internal antenna A2.

[0111] The normalized powers An, An′, An″, An′″ correspond to the power of the signal received for each path at time t divided by the maximum power value of the signal received within the observation duration. It should be noted that here, for Figures 3a to 3d , the normalized power or the absolute power of the signal can be used.

[0112] Then, the decay period "I" of the signal power is calculated for each module based on the predefined power threshold T. The decay period "I" is obtained by calculating the period between the following two moments: the moment when the normalized power exceeds the predefined power threshold T, and the moment when the normalized power becomes lower than the predefined power threshold T.

[0113] By setting the power threshold T to 0.4 (i.e. 40% of the maximum power), Figure 3a The decay period I in is calculated as follows:

[0114] [Mathematical formula 1] I = t1-t0

[0115] in,

[0116] I: decay period, in time (u),

[0117] t0: the time when the normalized power An exceeds the threshold T,

[0118] t1: The time when the normalized power An becomes lower than the threshold T.

[0119] By applying the calculation of the decay period "I" of the signal power based on a predefined power threshold T to each module ER1, ER2, we obtain:

[0120] exist Figure 3a , t0 equals 30, t1 equals 36, and therefore I equals 6.

[0121] By applying the same formula to the curve Figure 3b , 3c , 3d, in Figure 3b Obtained from:

[0122] [Mathematical formula 2] I′=t1′-t0′=27-13=14

[0123] exist Figure 3c middle:

[0124] [Mathematical formula 3] I″=t1″-t0″=32-15=17

[0125] exist Figure 3d middle:

[0126] [Mathematical formula 4] I″′=t1″′-t0″′=51-30=21

[0127] The decay periods I, I', I", I'" are then compared with a predetermined reference period Iref (step E8).

[0128] Figure 5a A vehicle V, an outer zone Z1 and an inner zone Z2, and a boundary F between the two zones are shown. By placing a portable device P at the boundary F defining the two zones Z1, Z2 (i.e., the outer and inner portions of the vehicle V), Figure 5a ), and predetermine the reference period Iref by performing the following steps:

[0129] a. measure the PDP or power delay profile of the multipath UWB signal received by each antenna A1, A2,

[0130] b. For each normalized power value An (received power divided by maximum power), calculate the decay period I of the UWB signal received by the external antenna A1 and the internal antenna A2. Then for each antenna A1, A2, obtain Figure 5b The curve shown.

[0131] A curve is then obtained showing the reference period Iref as a function of the normalized power An (see Figure 5b ). Figure 5b The curve obtained for the first antenna A1 is shown.

[0132] If the portable device P is located on the boundary P, the reference period Iref of the UWB signal received by the internal antenna A2 or the external antenna A1 is calculated according to Figure 5b The curve shown varies as a function of the normalized power. A curve of the decay period I of the normalized power An is then obtained for each antenna A1 , A2 .

[0133] exist Figure 5b In FIG. 1 , if the power threshold T is set to 0.4, a reference period Iref equal to 13 is obtained for the first antenna A1. For the second antenna A2, this reference period Iref may be different.

[0134] Then, it is determined whether the position of the portable device P is inside or outside the vehicle V based on the comparison between the decay periods I, I′, I″, I″′ calculated for each antenna A1, A2 and at least one of their reference periods Iref. The antenna whose decay period I, I′, I″, I″′ has the largest deviation with respect to its reference period Iref corresponds to the position of the portable device P relative to the vehicle V (step E9).

[0135] For explanation purposes only, here, the two antennas A1 , A2 will be considered to have the same reference value, ie, Iref equal to 13.

[0136] Similarly, in order to simplify the description of the present invention, the comparison between the decay periods I, I′, I″, I″′ and a single reference period Iref will be given as an example. However, if according to Figure 5b The curve shown repeats the comparison for a plurality of reference periods Iref selected for various values ​​An of the normalized power, then the accuracy of the position determination of the portable device P can be improved.

[0137] In this case, Figure 3a and 3b In the example, since the decay periods measured by the external antenna A1 and the internal antenna A2 are respectively: I equals 6 and I′ equals 14, I exhibits a greater deviation relative to Iref (equal to 13), namely:

[0138]

Mathematical formula 5

[0139] In this case, the decay period measured by the external antenna A1 has a greater variation relative to the reference period Iref, from which it is deduced that the portable device P is located outside the vehicle V, in the external zone Z1 (step E10b) and the unlocking of the vehicle V can be authorized (step E11b).

[0140] On the contrary, Figure 3c and 3d In the example, since the decay periods measured by the external antenna A1 and the internal antenna A2 are respectively: I″=17, I″′=21, I″′ shows a greater deviation relative to Iref (equal to 13), namely:

[0141]

Mathematical formula 6

[0142] In this case, the decay period measured by the interior antenna A2 has a greater variation relative to the reference period Iref, from which it is deduced that the portable device P is located inside the vehicle, in the interior zone Z2 (step E10a ), and the start of the vehicle V can be authorized (step E11a ).

[0143] The present invention thus enables determination of whether a portable device P is located inside or outside a vehicle V by clever use of multipath ultra-wideband signals.

[0144] The present invention is low-cost because it only requires two antennas, a transceiver module and an analysis and processing component M1 to robustly overcome the shortcomings of the prior art.

Claims

1. An activation method for activating a vehicle (V) function by means of an ultra-wideband (UWB) communication by means of a portable user device (P), the portable user device (P) performing ultra-wideband communication with an activation device (D) on board the vehicle (V), activating the vehicle (V) function according to the position of the portable device (P) relative to a boundary (F) between an inner zone (Z2) and an outer zone (Z1) of the vehicle (V), the activation method being characterized in that it comprises the following steps: a) The vehicle is pre-equipped with an internal antenna (A2) and an external antenna (A1), b) determining the presence of the portable device in an authorized area around the vehicle (V), c) storing the power delay (PDP) of the multipath UWB signal received by each antenna (A1, A2) according to time, d) determining for each antenna (A1, A2) and for a power threshold (T) a decay period (I, I', I", I'") of the received power, e) comparing said decay periods (I, I', I", I'") with at least one reference period (Iref), f) determining, based on the result of said comparison, whether the portable device (P) is located in the inner zone (Z2) or the outer zone (Z1), g) activating a vehicle function corresponding to the location of the portable device (P), Wherein a reference period (Iref) is predetermined as a function of received signal power for each antenna (A1, A2) when the portable device (P) is located on a boundary (F) between an interior zone (Z2) and an exterior zone (Z1) of a vehicle (V).

2. The activation method according to claim 1, characterized in that: The decay periods (I, I', I", I'") are determined for several power thresholds (T) and compared with several corresponding reference periods (Iref).

3. The activation method according to claim 1 or 2, characterized in that: The vehicle (V) function comprises an opening means for unlocking the vehicle (V) when the portable device (P) is located in the external zone (Z1).

4. The activation method according to claim 1 or 2, characterized in that: The vehicle (V) function includes starting the vehicle (V) when the portable device (P) is located in an interior zone (Z2) of the vehicle (V).

5. Device (D) for activating a vehicle (V) function by ultra-wideband (UWB), intended to be on board a vehicle (V) and to communicate with a portable user device (P) by ultra-wideband, activating a vehicle (V) function according to the position of the portable device (P) relative to a boundary (F) between an interior zone (Z2) and an exterior zone (Z1) of the vehicle (V), said device (D) comprising an electronic management unit (BCM) for controlling the activation of the function, characterized in that The device (D) comprises: a) Internal antenna (A2), b) External antenna (A1), c) determination means for determining the presence of the portable device (P) in an unlocking zone around the vehicle (V), d) an analysis and processing component (M1) for analyzing and processing multipath ultra-wideband signals received by the antennas (A1, A2), adapted to: i) storing the power delay (PDP) of the multipath UWB signal received by each antenna (A1, A2) according to time, ii) determining a decay period (I, I', I", I'") for each antenna (A1, A2) and for a power threshold (T), iii) comparing said decay periods (I, I', I", I'") with at least one reference period (Iref), iv) determining, based on the result of said comparison, whether the portable device (P) is located in the inner zone (Z2) or the outer zone (Z1), v) activating a vehicle function corresponding to the location of the portable device (P), Wherein a reference period (Iref) is predetermined as a function of received signal power for each antenna (A1, A2) when the portable device (P) is located on a boundary (F) between an interior zone (Z2) and an exterior zone (Z1) of a vehicle (V).

6. The activation device (D) according to claim 5, characterized in that The analysis and processing component (M1) is included in a transceiver module (ER1, ER2) of a vehicle (V).

7. A vehicle function activation system comprising an activation device (D) according to claim 5 or 6 and a portable user device (P), the system being characterized in that the analysis and processing component (M1) is also included in the portable device (P).

8. A vehicle function activation system by ultra-wideband (UWB), comprising an activation device (D) intended to be onboard a vehicle (V) and a portable user device (P), the device (D) and the portable device (P) communicating with each other by ultra-wideband (UWB), activating a vehicle (V) function according to the position of the portable device (P) relative to a boundary (F) between an inner zone (Z2) and an outer zone (Z1) of the vehicle (V), the system being characterized in that: a) the device (D) comprises an electronic management unit (BCM) controlling activation of the function, an internal antenna (A2), an external antenna (A1), at least one transceiver module (ER1, ER2) connected to the antennas (A1, A2), a determination component for determining the presence of a portable device (P) in an unlocking zone around the vehicle (V), b) the portable device (P) comprises an analysis and processing component (M1) for analyzing and processing multipath ultra-wideband signals received by the antennas (A1, A2), which is adapted to: i) storing the power delay (PDP) of the multipath UWB signal received by each antenna (A1, A2) according to time, ii) determining a decay period (I, I', I", I'") for each antenna (A1, A2) and for at least one power threshold (T), iii) comparing said decay periods (I, I', I", I'") with at least one reference period (Iref), iv) determining, based on the result of said comparison, whether the portable device (P) is located in the inner zone (Z2) or the outer zone (Z1), v) activating a vehicle function corresponding to the location of the portable device (P), Wherein a reference period (Iref) is predetermined as a function of received signal power for each antenna (A1, A2) when the portable device (P) is located on a boundary (F) between an interior zone (Z2) and an exterior zone (Z1) of a vehicle (V).

9. A motor vehicle (V), characterized in that It comprises an activation device (D) according to claim 5 or 6.

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