Presence detection method implemented in a motor vehicle

Abstract

A presence detection method (100) implemented within a motor vehicle, and using a return pulse signal resulting from the reflection on a target of an emitted pulse signal, the return pulse signal and the emitted pulse signal each being made up of radio frequency pulses, the presence detection method (100) comprising the following steps: a / generation (101) of sampled data (I, Q) relating to the return pulse signal; b / for each of a plurality of successive time intervals (ΔTj), extraction (102) of the sampled data located in said time interval (ΔTj), and relating to sampling instants for which the deviation at an emission instant of a respective pulse of the emitted pulse signal (SE) is less than a predetermined threshold;c / for each of the said successive time intervals (ΔTj), and using the values ​​extracted in step b / , calculation (103) of a phase shift value (φ(ΔTj)) between the return impulse signal and the emitted impulse signal; then d / use of the phase shift values ​​(φ(ΔTj)) to identify the presence or absence of a user. Figure 1;

Description

Title of the invention: Presence detection method implemented in a motor vehicle Technical field

[0001] The invention relates to the automotive field and more particularly to a presence detection method, implemented within a motor vehicle to detect the presence of a user in the immediate vicinity of an element such as a door handle. State of the art

[0002] Presence detection devices implemented within a motor vehicle are known in the prior art, based on the use of an electrode coupled to capacitive measurements.

[0003] A disadvantage of solutions based on capacitive technology is that they can be vulnerable to disturbances from the external environment such as rain droplets.

[0004] An objective of the invention is to propose a solution making it possible to implement presence detection within a motor vehicle, which is robust to disturbances such as raindrops while maintaining reduced bulk and complexity. Statement of the invention

[0005] This objective is achieved with a presence detection method implemented within a motor vehicle, and using a return pulse signal resulting from the reflection on a target of an emitted pulse signal, the return pulse signal and the emitted pulse signal each being made up of radiofrequency pulses.

[0006] The presence detection method comprises the following steps: a / generation of sampled data to the return pulse signal; b / for each of a plurality of successive time intervals, extraction of the sampled data located in said time interval, and relating to sampling times for which the deviation from an emission time of a respective pulse of the emitted pulse signal is less than a predetermined threshold; c / for each of said successive time intervals, and using the values ​​extracted in step b / , calculation of a phase shift value between the return pulse signal and the emitted pulse signal; then d / use of phase shift values ​​to identify the presence or absence of a user.

[0007] Throughout the text, the term “radio frequency” refers to a signal whose carrier frequency is between 3 kHz and 300 GHz. Preferably, the carrier frequency is, in the invention, between 5 GHz and 20 GHz, more preferably between 5 GHz and 10 GHz.

[0008] In use, the target is for example the hand of a user.

[0009] The data sampled from the return pulse signal correspond for example to the sampled values ​​of an in-phase component and a quadrature-phase component of the return pulse signal.

[0010] The method according to the invention may comprise the steps of transmitting the transmitted pulse signal and receiving the return pulse signal.

[0011] One of the ideas underlying the invention is to detect the presence or absence of a user, via gesture detection. The detection of a gesture indicates the presence of a user, and vice versa.

[0012] Gesture detection is based on radar technology, making it robust to disturbances such as raindrops while maintaining reduced footprint and complexity.

[0013] In a manner known per se, gesture detection by radar technology is based on the emission of a radiofrequency signal towards a reception zone, and the reception of a return signal resulting from the reflection of the emitted radiofrequency signal, on at least one target located in the reception zone.

[0014] The most economical systems are based on simple time-of-flight calculations: for each of a plurality of sampling instants, the time taken by the radiofrequency signal for the round trip between a transmitter-receiver and the target is determined. This time indicates a current distance to the target. A disadvantage, however, is that the accuracy in determining the current distance to the target is limited by the sampling frequency. However, this sampling frequency cannot be increased indefinitely without leading to boundary conditions of spectrum folding (Shannon criterion). Thus, typical values ​​of the sampling frequency are 1 GHz, or a period of one nanosecond. This corresponds to an accuracy of only 15 cm in determining the current distance to the target.This precision is insufficient in the context of presence detection, based on the detection or not of a gesture in the immediate vicinity of a radar module, i.e. often less than 10 cm from a radar module.

[0015] The invention therefore proposes, in order to overcome this limitation, to use phase shift measurements instead, variations in this phase shift indicating the presence or absence of a gesture.

[0016] Furthermore, in order to spatially circumscribe the presence detection, the invention proposes to use only data relating to sampling instants for which the difference from an instant of emission of a pulse respective of the emitted pulse signal is lower than a predetermined threshold. Said predetermined threshold is a threshold in units of time, easily convertible into a threshold in units of distance delimiting the maximum range of the presence detection. This ensures that the presence detection corresponds to a presence detection in the immediate vicinity of a transmitter-receiver module carrying out the emission of the emitted pulse signal and the reception of the return pulse signal.

[0017] Advantageously, step d / comprises the following sub-steps: di / for each of said successive time intervals, calculation of a derivative value of the phase shift; d-ii / comparison between said phase shift derivative value and the limits of at least one predetermined interval; d-iii / for a time window of predetermined width enclosing a plurality of said successive time intervals, calculation of a final value of a counter, the value taken by the counter being incremented by at least one unit each time the derivative value of the phase shift is included in the at least one predetermined interval; d-iv / comparison between the final value of the counter and a counter threshold, and generation of a high or low response value depending on whether the final value of the counter is lower or higher than the counter threshold; dv / successive shifts of the time window, and new iteration of steps d-iii / and d-iv / , so as to construct a response signal formed by the sequence of high or low response values; and d-vi / use of the response signal to identify the presence or absence of a user.

[0018] The phase shift derivative values ​​characterize a speed of the target. By comparing a phase shift derivative value with the limits of at least one predetermined interval, it is verified whether a movement of the target has the speed characteristics of a gesture expected from the user.

[0019] By using a wide time window, and a counter whose value is incremented each time it is considered that the movement of the target has the expected speed characteristics, it is ensured that a presence detection based on an analysis of the speed of the target is stabilized. This stabilization of the presence detection ensures great robustness with respect to noise and disturbances of the environment.

[0020] By sliding the time window in time, a binary response signal is progressively constructed, taking a high or low value depending on whether or not a stabilized movement of the target presenting predetermined speed characteristics has been detected.

[0021] This response signal is then used to identify the presence or absence of a user. For example, information relating to presence detection can be generated as soon as the response signal makes a jump from a low value to a high value. Alternatively, the information relating to presence detection is only generated if, in addition, the high value is maintained for a duration greater than a predetermined threshold.

[0022] Preferably, in step di / , the phase shift derivative value is calculated using a difference between the phase shift value associated with the time interval considered and the phase shift value associated with the immediately preceding time interval.

[0023] Advantageously, the successive time intervals all have the same time width AT and follow each other immediately two by two.

[0024] Preferably, the successive shifts of step dv / define a series of positions of the time window, distributed temporally according to a regular distribution step.

[0025] The distribution step of the positions of the time window is advantageously equal to N*AT, with N an integer greater than or equal to unity.

[0026] Preferably, the width of the time window is between 50 and 200 times the distribution step of the positions of said window.

[0027] The method may further comprise a step of using the information relating to the presence or absence of a user, to generate a command to lock or unlock an opening of the vehicle.

[0028] Preferably, the transmitted pulse signal is a UWB signal.

[0029] The invention also covers a system comprising: - a radar module, comprising an electrical oscillator, at least one radiofrequency antenna, at least one mixer and at least one analog-digital converter, and configured to emit the emitted pulse signal, receive the return pulse signal, and generate the sampled data relating to the return pulse signal; and - a calculation unit, comprising at least one memory and at least one processor, the at least one memory comprising program code instructions which, when executed by the at least one processor, configure said processor to implement steps b / and following of the method according to the invention.

[0030] The system may further comprise a door handle integrating the radar module.

[0031] The invention also relates to a computer program product comprising instructions for implementing steps b / and following of the method according to the invention when this program is executed by a processor. Description of figures

[0032] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This is purely illustrative and must be read in conjunction with the appended drawings in which:

[0033] [Fig-1] [Fig.l] schematically illustrates the steps of a method according to the invention;

[0034] [Fig.2] [Fig.2] schematically illustrates a system according to the invention;

[0035] [Fig.3] [Fig.3] schematically illustrates sampled data relating to the return pulse signal;

[0036] [Fig.4] [Fig.4] illustrates an example of the evolution, as a function of time, of the value of the phase shift between the return pulse signal and the emitted pulse signal;

[0037] [Fig.5] [Fig.5] illustrates an example of the evolution, as a function of time, of the derivative of the phase shift between the return pulse signal and the emitted pulse signal;

[0038] [Fig.6] [Fig.6] schematically illustrates the time window of predetermined width used in the method according to the invention;

[0039] [Fig.7] [Fig.7] illustrates an example of the evolution, as a function of time, of the final counter value, as well as the counter threshold and the response signal constructed using the final counter values.

[0040] Detailed description of at least one embodiment

[0041] A particular example of method 100 and system 200 according to the invention is described below.

[0042] The method according to the invention is implemented within a motor vehicle. Its purpose is to detect the presence of a user in the immediate vicinity of an element such as a door handle or a vertical structural upright (B-pillar, for example).

[0043] The system 200 according to the invention is illustrated schematically in [Fig.2].

[0044] The system 200 comprises: - a radar module 210; and - a 220 computing unit.

[0045] The radar module 210 comprises, in a manner known per se, at least one electrical oscillator, at least one radiofrequency antenna, at least one mixer and at least one analog-digital converter.

[0046] It is configured to: - emit a pulsed signal emitted SE, in the direction of a target 208 located in use outside the vehicle; - receive a return pulse signal SR, corresponding to a reflection (or backscattering) of the emitted pulse signal SE on the target 208; -performing in-phase mixing and quadrature-phase mixing between the return pulse signal and the transmitted pulse signal or its carrier, so as to generate data I(t) relating to an in-phase component of the return pulse signal SR and data Q(t) relating to a quadrature-phase component of the return pulse signal SR; and - carry out time sampling upstream or downstream of the mixing, to provide sampled data relating to the return pulse signal SR, here sampled data relating to the in-phase component I(t) and to the quadrature phase component Q(t) of the return pulse signal SR.

[0047] In use, the radar module 210 is placed for example inside a door handle, or in a vertical structural upright (B pillar, for example).

[0048] The emitted pulse signal SE is a radiofrequency signal, preferably of the UWB type.

[0049] Throughout the text, the term UWB (ultra-wide band) refers to a low-energy, wide-spectral radiofrequency signal. In particular, a UWB radiofrequency signal is defined by a ratio of the bandwidth divided by the center frequency that is greater than or equal to 20%, or by a bandwidth of 250 MHz or more.

[0050] The return pulse signal SR comes from the reflection, on a target, of the emitted pulse signal. It is therefore also a radiofrequency signal, for example of the UWB type, but whose characteristics such as the phase, the oscillation frequency, the amplitude, have been modified by the interaction with the target.

[0051] The computing unit 220 comprises at least one memory and at least one processor, the at least one memory comprising program code instructions which, when executed by the at least one processor, configure said processor to implement steps of the method as described below. The computing unit 220 may be arranged remotely relative to the radar module 210.

[0052] The calculation unit 620 is configured to provide, as output, information relating to the presence or absence of a user.

[0053] The method 100 according to the invention is illustrated in [Fig.l]. It comprises the steps detailed below.

[0054] Step 101:

[0055] The method according to the invention firstly comprises a step 101 of generating sampled data relating to the return pulse signal SR.

[0056] The sampling preferably has a sampling step between 0.8 ns and 2 ns, for example 1 ns.

[0057] In [Fig. 3], sampled data relating to the return pulse signal are schematically illustrated. They are presented in matrix form. A axis of the matrix corresponds to an index k of the pulse of the emitted pulse signal. An axis of the matrix corresponds to an index i of a sampling instant, the value of the index being reset to zero at each new pulse of the emitted pulse signal. A last axis of the matrix corresponds to the value S(k,i) taken by the sampled data, each value being associated with an index k of the pulse of the emitted pulse signal and with an index i of the sampling instant.

[0058] The values ​​S(k,i) preferably correspond to the values ​​of the in-phase component I(t) of the return pulse signal SR, and to the values ​​of the quadrature-phase component Q(t) of the return pulse signal SR.

[0059] The radar module 210 is configured to store the data S(k,i), then send them in packets to the calculation unit 620. The sending is done at regular intervals ATj.

[0060] The time intervals ATj each have the same time width, and follow one another directly. This time width is advantageously between 0.8 ms and 1.2 ms, for example equal to 1 ms.

[0061] Step 102:

[0062] The method then comprises, for each time interval ATj, a step of extracting the data S(k,i) situated in said time interval ATj, and relating to sampling instants for which the deviation from an instant of emission of a respective pulse of the emitted pulse signal SE is less than a predetermined threshold EC1.

[0063] The predetermined threshold EC1 defines a maximum time difference at an instant of emission of a respective pulse of the emitted pulse signal SE. It therefore corresponds to a maximum distance to the radar module 610, beyond which the return pulse signal SR is no longer used.

[0064] For example, a threshold is set at EC1 = 2 ns. This amounts to only considering the return pulse signal coming from a target located 30 cm or less from the radar module 610.

[0065] This ensures that only the most relevant data is selected in the context of detecting presence in the immediate vicinity of the radar module 6100.

[0066] Step 103:

[0067] The method then comprises, for each time interval ATj, a step of calculating a phase shift value <p(ATj) entre le signal impulsionnel retour SR et le signal impulsionnel émis SE.

[0068] Said phase shift value <p(ATj) est obtenue à l’aide des valeurs S(k,i) extraites à l’étape 102, et avec <p(t)=arctan (Q(t) / I(t)).

[0069] Preferably, the values ​​S(k,i) relating to different pulses k, and possibly to different sampling instants i, are combined together in the form of an arithmetic mean for the calculation of <p(ATj).

[0070] [Fig.4] illustrates an example of the evolution, as a function of time, of the value of the phase shift <p(ATj) entre le signal impulsionnel retour et le signal impulsionnel émis. L’axe des abscisses est le temps, l’axe des ordonnées est un angle qui varie ici entre -180° et +180°. Sur la [Fig.4], l’axe du temps s’étend sur une durée d’environ 1 seconde.

[0071] In [Fig.4] we observe zones with rapid variations in the phase shift (on the left and right in [Fig.4]), and a zone ZI with a slow variation in the phase shift (in the center in the figure).

[0072] The areas with rapid variations in the phase shift roughly correspond to the times at which the detected movement is a parasitic, relatively erratic movement.

[0073] Conversely, the zone ZI roughly corresponds to the times at which the target makes a relatively regular movement, corresponding to an approach gesture made deliberately by a user, and indicating its presence.

[0074] At this stage, however, it is difficult to precisely discriminate between a voluntary approach gesture and a parasitic movement.

[0075] Step 104:

[0076] The method then comprises, for each time interval ATj, a step of calculating the time derivative of the phase shift dq>(ATj) / dt.

[0077] We preferably have: dq>(ATj ) / dt= ( <p(ATj )- <p(ATj4 )) / AT, avec AT la largeur temporelle des intervalles temporels ATj.

[0078] The value AT being a constant, we can consider in the process that dq>(t) / dt= Ç>(ATk )- 9(ATk4 ).

[0079] In other words, the derivative value of the phase shift associated with the time interval ATj is considered to be equal to the difference between the phase shift value associated with the time interval considered ATj and the phase shift value associated with the immediately preceding time interval ATj4.

[0080] [Fig.5] illustrates an example of the evolution of the derivative of the phase shift as a function of time. The abscissa axis is time, the ordinate axis is an angle in degrees.

[0081] We identify in [Fig.5]: - a region 51 in which the values ​​of the phase shift derivative vary, while remaining close to the zero value; and - two regions 52 in which the values ​​of the phase shift derivative take high values ​​in absolute value.

[0082] One of the reflections underlying the invention is that it is not possible, on the basis of [Fig.5] alone, to directly make a reliable distinction between high phase shift values ​​linked to erratic movement of the target, and values high phase shift values ​​that can be obtained even in the presence of a voluntary gesture made by the target.

[0083] These high phase shift values, obtained even in the presence of a voluntary gesture, may correspond to localized but sudden variations in the phase (zones 44 in [Fig.4]) which are linked simply to the fact that the phase shift values ​​take values ​​modulo 2*ji (circular nature of the phase).

[0084] Step 105:

[0085] In a subsequent step, said phase shift derivative value d is compared <p(atj )) dt avec les bornes d’au moins un intervalle prédéterminé.

[0086] Here, the at least one predetermined interval comprises a low interval Ib and a high interval Ih, together framing the zero value.

[0087] Preferably, the low interval Ib and the high interval Ih are symmetrical around the zero value of the derivative of the phase shift. This amounts to comparing the absolute value of the derivative of the phase shift with the limits of at least one predetermined interval.

[0088] The fact that the current value of the derivative of the phase shift is included in the low interval Ib or in the high interval Ih, indicates that the phase shift presents variations characteristic of a voluntary gesture. In other words, the speed of the target is regular, and circumscribed between a maximum speed and a minimum speed characteristic of a voluntary gesture.

[0089] For example, we have Ih between 0.1° and P, and Ib between -0.1° and -P, with P between 5° and 30°, for example P=20°.

[0090] Step 106:

[0091] For a time window 65 of predetermined width framing a plurality of said successive time intervals AT), the final value Cfn of a counter is calculated, the value taken by the counter being incremented by at least one unit each time that the derivative value of the phase shift d <p(atj)) dt est comprise dans l’au moins un intervalle prédéterminé ib, ih. For a time window of predetermined width, the final value of a counter Cf; is calculated.

[0092] The calculation of step 106 therefore uses: - a counter with a predetermined initial value, preferably the zero value; and - the phase shift derivative values ​​associated with each of the intervals AT] temporal windows located in time window 65.

[0093] The counter is incremented by at least one unit each time one of said phase shift derivative values ​​is included in at least one predetermined interval Ib, Ih. In other cases, the value of the counter is not modified.

[0094] Advantageously, the counter is incremented by exactly one unit each time a phase shift derivative value is included in at least one pre-interval determined Ib, Ih.

[0095] In variants, we use: - several intervals, symmetrical two by two and increasingly distant from a zero value of the derivative of the phase shift; and - an increment value that gradually increases as it approaches the zero value of the phase shift derivative.

[0096] It is thus possible to ensure that the value taken by the counter increases all the more quickly as the movement of the target is regular.

[0097] As mentioned above, two intervals surrounding the zero value are used here. The zero value is excluded to avoid incrementing the counter in the absence of a target movement.

[0098] In variants, a single interval incorporating the zero value is considered. It is then ensured that the counter is not incremented in the absence of movement of a target, using data relating to the amplitude of the return pulse signal.

[0099] Step 107:

[0100] The final value of the counter Cfn is then compared with a counter threshold Sc, and a high or low response value Rn is generated depending on whether the final value of the counter Cfn is lower or higher than the counter threshold Sc. Sc is for example between 10 and 15.

[0101] Step 108:

[0102] The position of the time window is then temporally shifted by an AF shift value. The time window 65 thus forms a sliding window.

[0103] Steps 106 and 107 are then repeated for the new position of the time window.

[0104] The successive shifts of the time window 65 thus gradually construct a response signal formed by the sequence of response values ​​Rn. The index n (see Rn and Cfn) relates to the successive positions of the time window.

[0105] [Fig.6] schematically illustrates the time window 65 of predetermined width, for four successive positions of the latter. The successive positions of the time window are spaced two by two in a regular manner, with a time interval AF between two successive positions of the time window.

[0106] The distribution step AF of the positions of the time window is equal to the distribution step AT of the time intervals ATj considered, or to an integer multiple of said distribution step AT.

[0107] Advantageously, the sliding window has a temporal width Tw which is between 50 and 200 times the distribution step AF of the positions of said window.

[0108] For example, Tw=100 ms, AT= ms, and AF= 1 ms.

[0109] In [Fig.6], the abscissa axis is time, the ordinate axis is an angle. The [Fig.6] also shows a curve 66 schematically representing the evolution, as a function of time, of the phase shift <p(t) mentionné ci-avant.

[0110] Advantageously, the steps described above are repeated at least until a final counter value Cfn greater than the counter threshold Sc is obtained.

[0111] We have also represented, in [Fig.7]: - a curve 71 representing the evolution of the final value of the counter as a function of the position taken by the time window, and therefore as a function of time, in the presence of a voluntary approach gesture indicating the presence of the user; - a line 72 representing the value of the counter threshold Sc; - a curve 73 representing the evolution of the final value of the counter, in the presence of a parasitic movement; and - a template 74 representing the response signal formed by the sequence of response values ​​Rn.

[0112] The template 74 initially takes a low value, indicating an absence of voluntary gesture. It switches to a high value as soon as the curve 71 (final value of the counter) exceeds the line 72 (counter threshold Sc). It then returns to the low value as soon as the curve 71 (final value of the counter) falls below the line 72 (counter threshold Sc).

[0113] The template 74 is constructed as the time window is shifted successively.

[0114] Step 109:

[0115] Then, the response signal formed by the sequence of response values ​​Rn is used to identify the presence or absence of a user.

[0116] In particular, information relating to the presence of a user can be generated as soon as the response signal changes from the low value to the high value.

[0117] Alternatively, information relating to the presence of a user is generated as soon as the response signal changes from the low value to the high value, and remains there for a duration greater than or equal to a predetermined threshold.

[0118] In an optional subsequent step, not shown, the information relating to the presence of a user is used to generate a command to lock or unlock an opening of the vehicle (depending on the initial state of the opening).

[0119] The steps of the method according to the invention are thus implemented repeatedly, until the response signal changes from the low value to the high value, then from the high value to the low value. This amounts to identifying the start and then the end of a gesture made near the radar module 210. By using a sliding window, the start time and the end time of the gesture are determined reliably. In particular, it is avoided to erroneously detect a succession of short gestures instead of a single long gesture.

[0120] In [Fig.l], and to facilitate understanding of the invention, step 108 of shifting the time window is shown after step 107 of comparing the final counter value with a counter threshold. In practice, however, step 108 can be carried out, i.e. starting the implementation of steps 106 and 107 relating to a following position of the time window, without waiting for steps 106 and 107 relating to a previous position of the time window to be completed.

[0121] In variants, the method according to the invention may comprise a preliminary step of detecting any movement, controlling a switch of the system 200 from a standby state to an active state. The detection of any movement may be based on a comparison between an amplitude of the return pulse signal and a predetermined amplitude threshold.

[0122] In still other variants, the sampled data generated in step 101 are corrected for a bias, or offset. This bias is linked in particular to the delay introduced by the radar module 210, and to the surrounding noise. This bias can be measured in a preliminary calibration step.

[0123] A particular example of the use of phase shift values ​​has been described above.

Claims

Claims

1. Method (100) for detecting presence implemented within a motor vehicle, and using a return pulse signal (SR) resulting from the reflection on a target (208) of a transmitted pulse signal (SE), the return pulse signal and the transmitted pulse signal each consisting of radiofrequency pulses, the method (100) for detecting presence being characterized in that it comprises the following steps: a / generation (101) of sampled data (I, Q) relating to the return pulse signal (SR); b / for each of a plurality of successive time intervals (ATj), extraction (102) of the sampled data located in said time interval (ATj), and relating to sampling instants for which the deviation from an instant of emission of a respective pulse of the emitted pulse signal (SE) is less than a predetermined threshold; c / for each of said successive time intervals (ATj), and using the values extracted in step b / , calculation (103) of a phase shift value ( <p(ATj)) entre le signal impulsionnel retour et le signal impulsionnel émis ; puis d / use of phase shift values ( <p(ATj)) pour identifier la présence ou non d’un utilisateur, l’étape d / comportant les sous étapes suivantes : di / for each of said successive time intervals (ATj), calculation (104) of a value of the derivative of the phase shift (dq>(ATj)) / dt); d-ii / comparison (105) between said phase shift derivative value (d <p(atj)) dt) et les bornes d’au moins un intervalle prédéterminé (ib, r) ; d-iii pour une fenêtre temporelle (65) de largeur encadrant pluralité desdits intervalles temporels successifs (atj), calcul (106) d’une valeur finale (cfn) d’un compteur, la prise par le compteur étant incrémentée unité chaque fois que dérivée du déphasage (d <p(atj)) est comprise dans t au ih) ;d-iv / comparison (107) between the final value of the counter (Cfn) and a counter threshold (72), and generation of a high or low response value (Rn) depending on whether the final value of the counter (Cfn) is lower or higher than the counter threshold; dv / successive shifts (108) of the time window (65), and new iteration of steps d-iii / and d-iv / , so as to construct a signal of response (74) formed by the sequence of high or low response values (Rn); and d-vi / use (109) of the response signal (74) to identify the presence or absence of a user.

2. Method (100) according to claim 1, characterized in that in step di / , the derivative value of the phase shift (d <p(atj)) dt) est calculée à l’aide d’une différence entre la valeur de déphasage (<p(aj)) associée l’intervalle temporel considéré (atj) et (<p(at j i)) immédiatement précédent (atj_i).

3. Method (100) according to claim 1 or 2, characterized in that the successive time intervals (ATj) all have the same time width AT and follow each other immediately two by two.

4. Method (100) according to claim 3, characterized in that the successive shifts of step dv / define a series of positions of the time window (65), distributed temporally according to a regular distribution step (AF).

5. Method (100) according to claim 4, characterized in that the distribution step (AF) of the positions of the time window (65) is equal to N*AT, with N an integer greater than or equal to unity.

6. Method (100) according to claim 4 or 5, characterized in that the width of the time window (Tw) is between 50 and 200 times the distribution step (AF) of the positions of said window.

7. Method according to any one of claims 1 to 6, characterized in that it further comprises a step of using the information relating to the presence or absence of a user, to generate a command for locking or unlocking an opening of the vehicle.

8. Method (100) according to any one of claims 1 to 9, characterized in that the transmitted pulse signal (SE) is a UWB signal.

9. System (200) comprising: - a radar module (210), comprising an electrical oscillator, at least one radiofrequency antenna, at least one mixer and at least one analog-to-digital converter, and configured to transmit the transmitted pulse signal, receive the return pulse signal, and generate the sampled data relating to the return pulse signal (SR); and - a computing unit (220), comprising at least one memory and at least one processor, the at least one memory comprising program code instructions which, when executed by the at least one memory,

10.

11. at least one processor, configure said processor to implement steps b / and following of the method (100) according to one of claims 1 to 8. The system (200) of claim 9, further comprising a door handle incorporating the radar module (210). Computer program product comprising instructions for implementing steps b / and following of the method (100) according to one of claims 1 to 8 when this program is executed by a processor.

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