METHOD FOR DETECTING PRESENCE INSIDE A LOCKED VEHICLE, ASSOCIATED DETECTION DEVICE

Abstract

The invention proposes a method for detecting presence inside a motor vehicle by means of a detection device (D) comprising at least one internal ultra-wideband (ULB) transmit / receive module (I1) capable of transmitting into the interior of the vehicle (V), the method comprising the following steps: a) Emission for a predetermined duration (Δt) of a plurality of waves (R), a portion of which comprises waves emitted in phase (I) and another portion comprising waves out of phase (Q) with each other, b) Reception of the reflected waves (RTG1, RTG2) comprising static and dynamic waves, and filtering (F1) of the static waves, c) Application of a low-pass filter (F2) to the received dynamic waves, d) Determination of a distance (D) with a dynamic target (TG1, TG2), e) Extraction from the received dynamic waves, of a first signal (SCH) representing the movement of a torso and a second signal (SAB) representing abdominal movement,f) Determination of a phase shift (Δφ) between the two signals, g) Comparison of the phase shift with a predetermined phase shift value (ΔφS), h) Detection of the presence of a child (E) or an adult (A) based on the comparison result. Figure for the abstract: Fig. 4,

Description

Title of the invention: METHOD FOR DETECTING PRESENCE INSIDE A LOCKED VEHICLE, ASSOCIATED DETECTION DEVICE Technical field

[0001] The invention relates to a method for detecting presence inside a vehicle which has been previously locked, an associated detection device. The invention applies particularly to the detection of young children, or a baby who may have been forgotten in the rear seats when the driver left the vehicle and locked it. Prior art

[0002] New automotive standards are emerging and now require manufacturers to detect a child aged 0 to 6 years in a vehicle for 10 seconds after the vehicle is locked. This is the case, for example, with the "EuroNCAP" standard. This standard is divided into three levels: a first level which triggers the horn and the activation of the vehicle's headlights in the event of detection; a second level which triggers the sending of a notification to the driver's phone; and finally a third level which triggers an emergency call, i.e. an "e-call" ("emergency call" in English) issued by the vehicle.

[0003] To warn the driver of the presence of a young child or a baby in a rear seat of a motor vehicle, several methods or devices of the prior art are known.

[0004] The majority of methods use dedicated sensors, for example a sensor on the rear seat belt, which detects that the belt is fastened, or infrared or radar sensors making it possible to detect the presence of an “object” on the rear seat, supplemented by the detection of a breathing movement, or sensors located under the rear seat which detect a weight or a camera which visualizes the environment near the rear seats.

[0005] However, the disadvantages of these dedicated sensors lie in their additional cost to the vehicle and the lack of respect for privacy in the case of use of the camera.

[0006] It is also known to use sensors already existing on the vehicle, for example UWB frequency transmitters / receivers, "Ultra Wide Band" or Ultra Wide Band, which are located on the vehicle in order to allow "hands-free" access to the vehicle and / or "hands-free" starting of the vehicle. These sensors are then used to detect the movement of breathing, i.e. the heart rate of a human located in the vehicle.

[0007] The advantage of using the ultra-wideband band lies in the frequency of the emitted waves which allows the waves to penetrate through clothing.

[0008] However, if UWB transmitters / receivers are used for presence detection inside the vehicle, they are not reliable enough to distinguish the presence of a child from that of an adult. Indeed, if it is detected that an adult is present in the back seat alone or with a child, it is not necessary to trigger an alert.

[0009] It is known from the prior art to use artificial intelligence which takes into account parameters such as respiratory rate, but it has become apparent that since the respiratory rates of a child and an adult can be very close, the use of artificial intelligence is not reliable or the time required for discrimination by data processing is too long.

[0010] The invention therefore proposes a method for detecting presence inside a vehicle; as well as an associated detection device, making it possible to discriminate the presence of a child from that of an adult in a reliable and inexpensive manner. Statement of the invention

[0011] The invention proposes a method for detecting presence inside a motor vehicle by a detection device comprising at least one internal ultra-wideband transmission and reception module capable of transmitting towards the interior of the vehicle, said method being remarkable in that it comprises the following steps: a. Transmission for a predetermined duration of a plurality of ultra-wideband waves, a part of which comprises waves transmitted in phase and another part of which comprises waves out of phase with each other, b. Receiving reflected waves including static waves and dynamic waves, and filtering static waves representing fixed obstacles, c. Applying a low-pass filter to the received dynamic waves, d. Determination of a distance to a dynamic target from the filtered dynamic waves, e. Extraction of the received dynamic waves from two oscillating signals, a first signal representing a movement of a torso and a second signal representing a movement of an abdomen, f. Determination of a phase shift between the first and second signals, g. Comparison of the phase shift with a predetermined phase shift value, h. Detection of the presence of a child or an adult based on the result of the comparison.

[0012] In an improvement of the method according to the invention, the method comprises in in addition to a determination and an amplitude comparison between an amplitude of the first signal and an amplitude of the second signal and in that the detection of a presence of a child or an adult is a function of the result of the phase shift comparison and the amplitude comparison between the two signals.

[0013] In a first embodiment of the detection method, the extraction of two oscillating signals is carried out by demodulation of the received dynamic waves.

[0014] In a second embodiment of the detection method, the extraction of the two oscillating signals is carried out by means of a prior spatial scanning of the waves emitted towards the target.

[0015] The invention also relates to a device for detecting a presence in a motor vehicle, comprising at least one internal ultra-wideband transmission and reception module capable of transmitting towards the interior of the vehicle, said device being remarkable in that it is also capable of: a. Emit for a predetermined duration ultra-wideband waves, part of which comprises waves emitted in phase and another part of which comprises waves out of phase with each other, b. Receive reflected waves including static waves and dynamic waves and filter out static waves, c. Apply a low-pass filter to the dynamic waves, d. Determine a distance to a dynamic target, e. Extract dynamic waves, two oscillating signals, a first signal representing the movement of a torso and a second signal representing a movement of an abdomen, f. Determine a phase shift between the first and second signals, g. Compare the phase shift with a predetermined phase shift value, h. Detect the presence of a child or an adult based on the result of said comparison.

[0016] In the improvement of the invention, the detection device is further capable of a. determine an amplitude of each of the two signals, b. compare the two amplitudes with each other c. .detect the presence of a child or an adult based on the result of the comparison between the two amplitudes and based on the comparison between the phase shift and the predetermined phase shift value.

[0017] In the first embodiment, the device is capable of demodulating the received dynamic waves to extract the two oscillating signals.

[0018] In the second embodiment, the device is capable of carrying out a preliminary spatial scan of the waves emitted towards the target.

[0019] The invention applies to any computer program product comprising program code instructions for executing the steps of the method according to any one of the characteristics listed above when said program is executed on a computer.

[0020] Finally, the invention applies to any motor vehicle comprising a detection device according to any one of the characteristics listed above. Brief description of the drawings

[0021] 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:

[0022] [Fig.l]: [Fig.l] is a schematic representation of a vehicle V equipped with the detection device according to the invention,

[0023] [Fig.2]: [Fig.2], is a schematic representation of the desynchronized breathing between the abdomen and the torso of a baby,

[0024] [Fig.3] :1a [Fig.3] is a schematic representation of the transmission and reception of reflected waves in ultra wide band between a transmission reception module and a first target consisting of a child and between the transmission module and a second target consisting of an adult,

[0025] [Fig.4]: [Fig.4] is a graph representing the amplitude of the respiratory signals from the abdomen and torso that are reflected when the target is a child, as a function of time,

[0026] [Fig.5]: [Fig.5] is a graph representing, over time, the emission frames of ultra-high frequency waves,

[0027] [Fig.6]: [Fig.6] comprises two graphs, which represent, according to time, on the upper graph the reflected waves as a function of time before the filtering of the static waves and on the lower graph, the reflected waves as a function of time, after the filtering of the static waves,

[0028] [Fig.7]: [Fig.7] comprises two graphs, representing over time, for the left graph, the reflected waves before demodulation, and on the right graph the reflected waves after demodulation, according to a first mode of extraction of the two oscillating signals,

[0029] [Fig.8]: [Fig.8] comprises a graph and a diagram, the graph represents the amplitude of the two oscillating signals of the torso and the abdomen and the diagram illustrates the scanning of the waves emitted towards the target, according to a second embodiment of extraction of the oscillating signals,

[0030] [Fig.9]: [Fig.9] represents the detection device D according to the invention,

[0031] [Fig. 10]: [Fig. 10] is a flowchart representing the detection method according to the invention. Description of the embodiments

[0032] In [Fig.l] a vehicle V is shown equipped with a detection device D according to the invention, the device comprises at least one internal module II for transmitting and receiving in ultra wide band ULB capable of transmitting towards the interior of the vehicle, that is to say in a multidirectional manner in the passenger compartment of the vehicle.

[0033] Preferably, the internal module II is located centrally in the passenger compartment in order to be able to emit R waves throughout the passenger compartment.

[0034] Ultra Wide Band (UWB) communication is understood to mean radiofrequency communication which is based on the transmission of very short pulses, often less than a nanosecond. Thus, the bandwidth can reach very high values ​​between 250 and 500 MHz.

[0035] The internal transmission and reception module II is electronically connected to a central control unit 10 which manages the transmission and reception of data via said module and which also processes this data. This is known from the prior art. Of course, the central control unit 10 and the internal transmission and reception module II may be one and the same and be integrated together in the same unit.

[0036] According to the invention, the device D is further capable of: a. Emit for a predetermined duration At ultra wide band ULB R waves, part of which comprises waves emitted in phase I and another part comprises waves out of phase Q with each other, b. Receive the reflected waves RTG1, RTG2 including static waves and dynamic waves and filter the static waves, c. Apply a low-pass filter F2 to the dynamic waves S, d. Determine a distance D with a target TGI, TG2 on which the waves are reflected, e. Extract from the dynamic waves S two oscillating signals, a first signal SCH representing the movement of a torso CH and a second signal SAB representing a movement of an abdomen AB, f. Determine a phase shift Aq> between the first signal SCH and the second signal SAB, g. Compare the phase shift Aq> with a predetermined phase shift value Aq>S, h. Detect the presence of a TG2 child or a TGI adult depending on the result of said comparison.

[0037] For this purpose, the detection device D comprises: a. Means of Ml emissions in ultra wide band ULB of R waves in phase I and out-of-phase waves Q between them, b. Means for receiving reflected waves and filtering static waves M2, c. M3 low-pass filtering means for dynamic S waves, d. Means for determining M4 a distance D with a dynamic target TGI, TG2, from dynamic waves, e. Means for extracting M5 two oscillating signals SCH, SAB from the dynamic waves thus filtered, f. Means for determining M6 a phase shift Aq> between the two oscillating signals SCH, SAB, g. Comparison means M7 between the phase shift Aq> and a predetermined phase shift value Aq>S, h. Means of M8 detection of the presence of a TG2 child or a TGI adult depending on the result of the comparison.

[0038] In a preferred embodiment of the device D, illustrated in [Fig.9]; the transmission means M1, the means for receiving and filtering static waves M2, the low-pass filtering means M3, the means for determining a distance M4, the extraction means M5, the determination means M6, the comparison means M7 and the detection means M8 are in the form of software and are integrated into the central control unit 10.

[0039] The central control unit 10 also comprises a processor 100 and a memory 101 (see [Fig.9]) in which instructions are recorded for configuring the processor to execute certain particular processing operations, in particular to implement the steps of the detection method, according to the embodiment as described below.

[0040] In a first embodiment of the invention, the extraction means M5 consist of a demodulation M51 (see [Fig.9]) of the reflected waves which make it possible to distinguish between two oscillating signals SAB and SCH. The techniques for demodulating signals in phase or out of phase with each other are known to those skilled in the art and will not be detailed further here.

[0041] In a second embodiment of the invention, the extraction means M5 consist of a prior spatial scanning of the waves emitted towards the target TGI, TG2 and by a method of spatial distinction M52 of the reflected waves. The spatial scanning uses the known state-of-the-art technique of beamforming, also called "beamforming" in English. This technique makes it possible to modify the radiation angle of the antenna of the internal module according to a vertical plane.

[0042] The angular resolution depends on the frequency of the emitted waves. In the ultra-wideband frequency band, the minimum resolution to be used is 10°. The scanning angular is + / -30° to cover the abdomen and torso of a TGI, TG2 target.

[0043] Preferably, the wave emission means Ml emit waves R in phase at 0° and phase-shifted by 90° between them, according to a plurality of frames Tl, T2...Tn of duration d of 100 ns each for a predetermined duration At of 10 seconds for example (see [Fig.5]).

[0044] The means for filtering the static waves M2 can be presented in different forms, known from the state of the art, said filtering means can consist of the analog ball filter or called "Loopback filter" in English, or the decomposition into singular values, also called "singular Value decomposition SVD" in English, or even averaging filters such as the Kalman filter or methods for calculating averages.

[0045] The low-pass filtering means M3 comprise a low-pass filter with a cut-off frequency of 1 Hz to keep only a signal representative of the movements linked to breathing.

[0046] The means M4 for determining a distance D with a target TGI, TG2, comprise means for determining a time of flight of the waves, thus allowing the calculation of the distance.

[0047] In an improvement of the invention, the device D is also capable of determining an amplitude ACH, AAB of each of the two signals SCH, SAB and of comparing the two amplitudes ACH, AAB with each other. In this improvement, the device D then also comprises means for determining the amplitude ACH, AAB of the two signals SCH, SAB and for comparing the two amplitudes with each other (not shown in [Fig.9]).

[0048] In this improvement, the device D then comprises means M8' for detecting a child TG2 or an adult TGlen as a function of the result of the comparison between the phase shift Aq> and the predetermined phase shift value Aq> S and as a function of the result of the comparison between the two amplitudes ACH, AAB.

[0049] Preferably, the predetermined phase shift value Aq>S is between 30° and 150°

[0050] The detection method, illustrated in [Fig. 10] will now be described.

[0051] During a first step E1, a plurality of ultra-wideband ULB R waves are emitted into the passenger compartment of the vehicle for a predetermined duration At. This plurality comprises in-phase I waves and out-of-phase Q waves, i.e. offset by 90°.

[0052] The R waves are sent in successive frames T1, T2...Tn with a duration of approximately 500 ps and at an interval between each frame of 10 ms. The duration of emission of the waves to detect a presence is 10 seconds. The maximum delay between the emission of a wave and the reception of the reflected wave corresponds to laying and 100 ns.

[0053] This train of frames is illustrated in [Fig.5].

[0054] A portion of the R waves thus emitted is reflected by any obstacle, whether fixed or dynamic, including any body in the passenger compartment, whether that of an adult TG2 or that of a child TGI (see [Fig.3]).

[0055] The reflected waves RTG1, RTG2 are received, during the second step E2 by the internal transmission reception module II (see [Fig.3]). On the left of [Fig.7], there is a graph illustrating the amplitude A(V) according to the time t(s) of the reflected waves RTG2, RTG1 and received by the internal module II.

[0056] The waves thus reflected include so-called “static” waves and so-called “dynamic” waves. “Static” waves are waves reflected by static obstacles and with which the distance between the internal module II and the obstacle does not vary. “Dynamic” waves are waves reflected by moving obstacles for example, and with which the distance between the internal module II and the obstacle varies. For example, a moving obstacle may be the torso or abdomen of an individual who is breathing. Indeed, during breathing the abdomen or torso moves by approximately 4 mm, the torso and abdomen are therefore dynamic targets.

[0057] In a third step E3, the detection method according to the invention proposes to filter the static waves with a filter F1 in order to keep only the dynamic waves. The filtering method is known to those skilled in the art as specified above: the filter can be in different forms, known from the state of the art, said filtering means can consist of the analog ball filter or called "Loopback filter" in English, or the singular value decomposition, also called "singular Value decomposition SVD" in English, or even averaging filters such as the Kalman filter or average calculation methods.

[0058] This filtering is illustrated in [Fig.6]. At the top of [Fig.6] is a graph representing the amplitude A in volts of the reflected R waves RTG1, RG2 as a function of time t in seconds. The waves represented here include static waves and dynamic waves.

[0059] At the bottom of [Fig.6], there is a graph representing the amplitude A of the reflected waves according to the time t in seconds after the filtering of the static waves. The signal S thus obtained is a sinusoidal signal whose amplitude and frequency are representative of the amplitude and frequency of the movement of the dynamic obstacle.

[0060] In a fourth step E4, it is proposed to apply a low-pass filter F2 with a cut-off frequency equal to 1 Hz to this signal, in order to keep only a signal S representative of the movement of a torso or an abdomen during breathing.

[0061] From the signal S thus filtered, during a fifth step E5, a distance D between the internal module and the dynamic target TGI, TG2. The distance D is determined by the time of flight of the UWB waves. This is known to those skilled in the art. Said distance D makes it possible to determine the position of said target TGI, TG2 and to extract the sinusoidal signals coming from the same target.

[0062] During a sixth step E6, two oscillating signals are extracted from this signal S; a first signal representing a movement of a torso SCH, and a second signal representing a movement of an abdomen SAB.

[0063] This extraction can be carried out in two different ways.

[0064] In a first embodiment, the signal S is demodulated in phase and in phase opposition. The demodulation is a method known to those skilled in the art and will not be detailed further here.

[0065] In a second embodiment, a spatial scan of the emitted ULB waves is carried out towards the target TGI, TG2 detected at the distance D determined beforehand. This scan, for example at an angle of 10°, makes it possible to send a plurality of beams of waves R towards the target and to receive two types of reflected signals. Those reflected by the abdomen AB and those reflected by the torso CH.

[0066] The spatial scanning is illustrated in [Fig.8]. The internal module II emits waves RI, R2 spatially offset from each other by a few degrees. For example, 10 degrees, thus scanning the upper part of the body, that is to say the torso CH, and the lower part, the abdomen AB of the target TGI, TG2. We thus receive in return the two oscillating signals spatially offset from each other, the signal reflected by the torso SCH, representing the breathing signal of the torso CH and the signal reflected by the abdomen SAB, representing the breathing signal of the abdomen AB.

[0067] The applicant has in fact noted that the functioning of a child's breathing is different from that of a TG2 adult. In this case, in an adult, ventral breathing and thoracic breathing are synchronized. Consequently, the reflected RTG2 waves received from the torso or abdomen of an adult form only one signal having a single amplitude and a single frequency. In reality, a plurality of signals can be obtained but whose amplitudes and frequencies are very close to each other, within a measurement tolerance.

[0068] On the contrary, in a baby or a child under 4 years old, ventral breathing and thoracic breathing are desynchronized. This is illustrated in [Fig.3] which includes a graph representing the desynchronized movements of the torso CH and the abdomen AB of a baby TGI when the latter breathes. It is clearly seen that when the abdomen AB rises, the torso CH collapses and vice versa. Consequently, the reflected waves RTG1 received from the torso or abdomen of a child TGI are made up of two types of waves, of different amplitude and frequency, a first signal SCH representing the breathing movement of the torso, and a second SAB signal representing the breathing movement of the abdomen.

[0069] The invention therefore proposes to extract these two signals SCH, SAB, representative of the breathing movement of the torso and that of the abdomen, and to compare them in order to determine whether the presence detected in the passenger compartment is that of a TG2 adult or that of a TGI child.

[0070] The signals thus extracted are represented in [Fig.4]. In [Fig.4], the amplitude variations of the first signal SCH representing the movement of the torso and of the second signal SAB representing the movement of the abdomen AB during breathing for a baby or a child are represented over time t(s).

[0071] Then in the next step (step E7a), a phase shift Aq> is calculated between the first SCH and the second signal SAB.

[0072] This phase shift Aq> is then compared to a predetermined phase shift value Aq>S (step E8a), for example greater than 30°.

[0073] If the phase shift Aq> is greater than the predetermined phase shift value Aq>S, then it is considered that the presence of a TGI child in the passenger compartment has been detected (step E10).

[0074] If the phase shift Aq> is less than the predetermined phase shift value Aq>S, then it is considered that the presence of an adult TG2 in the passenger compartment has been detected (step E9).

[0075] In an improvement of the invention, in step E7b, it is proposed to compare the amplitude of the first signal ACH with the amplitude of the second signal AAB (see step E7b).

[0076] Indeed, in TGI children, the amplitude of movement of the torso is higher than the amplitude of movement of the abdomen when the child breathes, i.e. ACH>AAB or if the variation in amplitude is equal to AA=ACH-AAB, then for a child this variation is higher than a predetermined amplitude threshold AA>AAS or the ratio between the amplitude of the torso and the amplitude of the abdomen is between AAAB / ACH is between 0.3 and 0.7.

[0077] There are then four possible cases: a. If the amplitude difference AA is greater than a predetermined amplitude threshold AAS and if the phase difference Aq> is greater than the predetermined phase shift value Aq>S then a TGI child is detected; b. If the amplitude difference AA is less than a predetermined amplitude threshold AAS and if the phase difference Aq> is less than the predetermined phase shift value Aq>S then a TG2 adult is detected; c. If the amplitude difference AA is greater than a predetermined amplitude threshold AAS and if the phase difference Aq> is less than the predetermined phase shift value Aq>S then the method returns to step El and the process is repeated, d. If the amplitude difference AA is less than a predetermined amplitude threshold AAS and if the phase difference Aq> is greater than the predetermined phase shift value Aq>S then the method returns to step El and the method is repeated.

[0078] The invention is therefore ingenious, inexpensive and easy to implement. By using a single internal ultra-wideband transmission and reception module, the detection method according to the invention makes it possible to reliably and robustly distinguish the presence of a child from that of an adult in the passenger compartment of the vehicle.

Claims

Claims

1. Method for detecting presence inside a motor vehicle by a detection device (D) comprising at least one internal ultra-wideband (ULB) transmission-reception module (II) capable of transmitting towards the interior of the vehicle (V), said method being characterized in that it comprises the following steps: a. Emission for a predetermined duration (At) of a plurality of waves (R) in ultra wide band (ULB) of which a part comprises waves emitted in phase (I) and another part comprises waves out of phase (Q) with each other, b. Reception of reflected waves (RTG1, RTG2) including static waves and dynamic waves, and filtering (Fl) of static waves representing fixed obstacles, c. Application of a low-pass filter (F2) on the received dynamic waves, d. Determination of a distance (D) with a dynamic target (TGI, TG2) from the filtered dynamic waves, e. Extraction of the received dynamic waves from two oscillating signals, a first signal (SCH) representing a movement of a torso and a second signal (SAB) representing a movement of an abdomen, f. Determination of a phase shift (Aq>) between the first (SCH) and the second signal (SAB), g. Comparison of the phase shift (Aq>) with a predetermined phase shift value (Aq>S), h. Detection of the presence of a child (TGI) or an adult (TG2) depending on the result of the comparison.

2. Detection method according to claim 1, characterized in that it further comprises a determination and an amplitude comparison between an amplitude of the first signal (ACH) and an amplitude of the second signal (AAB) and in that the detection of a presence of a child (TGI) or an adult (TG2) is a function of the result of the phase shift comparison and the amplitude comparison between the two signals (SCH, SAB).

3. Detection method according to claim 1 or 2, characterized in that the extraction of two oscillating signals (SCH, SAB) is carried out by demodulation of the received dynamic waves.

4. Detection method according to claim 1 or 2, characterized in that the extraction of the two oscillating signals (SCH, SAB) is carried out by means of a prior spatial scanning of the waves emitted (R) towards the target (TGI, TG2).

5. Device (D) for detecting a presence in a motor vehicle (V), comprising at least one internal ultra-wideband (ULB) transmission and reception module (II) capable of transmitting towards the interior of the vehicle (V), said device (D) being characterized in that it is further capable of: a. Emit for a predetermined duration (At) ultra wide band (ULB) waves, part of which comprises waves emitted in phase (I) and another part (Q) comprises waves out of phase with each other, b. Receive reflected waves (RTG1, RTG2) including static waves and dynamic waves and filter the static waves, c. Apply a low-pass filter (F2) to the dynamic waves, d. Determine a distance (D) with a dynamic target (TGI, TG2), e. Extract dynamic waves, two oscillating signals (SCH, SAB), a first signal (SCH) representing the movement of a torso and a second signal (SAB) representing a movement of an abdomen, f. Determine a phase shift (Aq>) between the first (SCH) and the second signal (SAB), g. Compare the phase shift (Aq>) with a predetermined phase shift value (Aq>S), h. Detect the presence of a child (TGI) or an adult (TG2) depending on the result of said comparison.

6. Detection device (D) according to the preceding claim, characterized in that it is further capable of: a. determine an amplitude (ACH, AAB) of each of the two signals (SCH, SAB), b. compare the two amplitudes (ACH, AAB) with each other c. .detect the presence of a child (TGI) or an adult (TG2) depending on the result of the comparison between the two amplitudes (ACH, AAB) and depending on the comparison between the phase shift (Aq>) and the predetermined phase shift value (AcpS).

7. Detection device (D), according to any one of claims 5 or 6, characterized in that the device (D) is capable of demodulating the dynamic waves received to extract the two oscillating signals (SCH, SAB).

8. Detection device (D) according to any one of claims 5 or 6, characterized in that the device (D) is capable of carrying out a preliminary spatial scan of the emitted waves (R) towards the target (TGI, TG2).

9. A computer program product comprising program code instructions for executing the steps of the method according to any one of claims 1 to 4 when said program is executed on a computer.

10. Motor vehicle (V), characterized in that it comprises a detection device (D) according to any one of claims 5 to 8.

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