Method for determining the opening of a vehicle opening and gesture detection system implementing this method

Abstract

Method for determining a position of a trunk opening of a vehicle comprising a radar antenna configured and positioned so as to emit a pulse signal in a substantially vertical direction, method comprising the following steps: - a preliminary step for determining by calculation or by measurements a range of possible distances that can separate the radar antenna and the trunk opening, - emission of a pulse signal, - reception of a return pulse signal, - measurement of a time difference between a pulse of the return pulse signal and a corresponding pulse of the emitted pulse signal, - estimation of a distance corresponding to the measured time difference knowing the speed of the signal, - if the estimated distance is included in the range of possible distances that can separate the radar antenna and the trunk opening,then it is considered to be the distance separating the radar antenna from the trunk opening Figure of the abstract: Figure 4,

Description

Title of the invention: Method for determining the opening of a vehicle opening and gesture detection system implementing this method

[0001] The present disclosure relates to a method for determining the opening of a vehicle opening and a gesture detection system implementing this method. Technical field

[0002] The present disclosure relates to the field of managing access to a motor vehicle. Prior art

[0003] It is known to use radiofrequency signals to control the opening of a motor vehicle door. A radiofrequency signal is an electromagnetic signal comprising a carrier with a frequency of, for example, between 3 kHz and 300 GHz but most often between 5 and 20 GHz in applications in the automotive world.

[0004] There are in particular gesture detection methods used for controlling a vehicle opening. In such a method, a radiofrequency signal is transmitted towards a target and the analysis of a return radiofrequency signal makes it possible to recognize a user's foot performing a predetermined gesture.

[0005] It is also known to use a pulse-type radiofrequency signal (as opposed to a continuous signal) having so-called radiofrequency pulses, i.e. whose carrier frequency belongs to the radiofrequency spectrum. In other words, the radiofrequency signal has a pulse-type modulation. The use of this type of signal makes it possible in particular to determine a distance between a target and a device for transmitting and receiving said pulse-type radiofrequency signal.

[0006] Source radiofrequency signal pulses are emitted and corresponding return radiofrequency signal pulses are detected on an amplitude signal, sampled temporally by an analog-to-digital converter. The frequency of the temporal sampling defines sampling time windows and thus a precision on the measurement of a duration taken by the pulse in question to make the round trip between the transmission / reception device and the target. To increase the precision of the measurement, the sampling frequency must be as high as possible. In practice, a precision of the order of ten centimeters is generally achieved, for example between 10 and 20 cm, for example approximately 15 cm.

[0007] There are more and more motorized openings on a vehicle, most often trunk doors. If an obstacle has been identified near the opening, it is appropriate to order a partial opening of only the opening. To then open the opening in question without the said opening encountering an obstacle, then it is often necessary to know the percentage of opening of the opening.

[0008] For cost reasons, opening motors are often all-or-nothing type actuators which do not provide an indication of the opening percentage of the controlled element. In the case where the motor makes it possible to know the position of the controlled opening, then for safety reasons, it is advantageous to check the opening rate given by the motor, with a redundant system.

[0009] The present disclosure aims to provide a method for determining the degree of opening of a vehicle opening, for example a trunk opening. Such a determination can then be used in an opening control to avoid a collision of said opening with a previously detected obstacle. Summary

[0010] The present disclosure then proposes a method for determining a position of a trunk opening of a vehicle, the vehicle comprising a radar antenna configured and positioned so as to emit a pulsed signal along a line of sight, the line of sight being oriented in a substantially vertical direction when the vehicle is resting on substantially horizontal ground, the vertical direction corresponding to a direction perpendicular to the ground on which the vehicle is located.

[0011] According to the present disclosure, this method comprises the following steps: -a- emission of at least one emitted pulse signal, -b- reception of at least one return pulse signal, -c- measurement of a time shift between a pulse of the return pulse signal considered and a corresponding pulse of the emitted pulse signal, -d- estimation of a distance corresponding to the measured time shift knowing the speed of the signal, -e- if the estimated distance is included in a range of possible distances that can separate the radar antenna and the trunk opening, then it is considered to be the distance separating the radar antenna from the trunk opening.

[0012] The features set out in the following paragraphs may, optionally, be implemented, independently of one another or in combination with one another:

[0013] - the radar antenna is a bidirectional antenna (one direction being used to determine a position of a trunk opening, the other direction being used to implement gesture detection as described below);

[0014] - the radar antenna is arranged closer to the ground than to the trunk opening in position closed;

[0015] - a preliminary step to determine by calculation or by measurements a range of possible distances that can separate the radar antenna and the trunk opening,

[0016] - the return pulse signal is sampled in time by a converter analog digital; and / or

[0017] - the method further comprises a step of determining the relative opening of the trunk opening.

[0018] According to another aspect, there is provided a computer program comprising instructions for implementing all or part of a method as defined herein when this program is executed by a processor / computer. According to another aspect, there is provided a non-transitory, computer-readable recording medium on which such a program is recorded.

[0019] According to another aspect, there is provided a computer intended to be installed in a motor vehicle comprising at least one processor and at least one memory, characterized in that it is configured for the implementation of steps -c- and following of a method as defined herein.

[0020] According to another aspect, there is proposed a trunk opening management system intended to be installed in a motor vehicle, characterized in that it comprises: - a transmission and reception module comprising at least one radar antenna, and configured to transmit and receive a pulsed radiofrequency signal, and - an electronic management module comprising a computer as defined above.

[0021] According to an alternative embodiment, in this trunk opening management system, the radar antenna of the transmission and reception module may be intended to transmit omnidirectionally, and the system advantageously further comprises at least one directional antenna intended to receive directionally.

[0022] According to another aspect, there is provided a gesture detection system for a motor vehicle, comprising: - a safe opening management system as described above, - a data extraction unit, configured to receive as input data from the transmission and reception module relating to a pulsed radiofrequency signal received by said module, and to extract therefrom first data relating to a first range of distances to the radar antenna of the transmission and reception module, and to further extract therefrom second data relating to a second range of distances to the radar antenna of the transmission and reception module; and - a gesture detection unit, configured to receive input data relating to at least one radiofrequency signal received by the transmission and reception module of the trunk opening management system, and to deduce therefrom information relating to the detection of a predetermined gesture, said gesture being intended to control the opening of an opening of the motor vehicle; said data relating to at least one radiofrequency signal received comprising at least said first data, extracted by the data extraction unit; and in which the calculator of the trunk opening management system is configured to use said second data extracted by the data extraction unit.

[0023] The production of such a gesture detection system is particularly advantageous because it pools resources between the trunk opening measurement and gesture detection functions. This pooling is made possible by the use of a pulsed radar signal which makes it possible to extract data relating to different detection zones. Pooling the trunk opening measurement function with other functions using a pulsed signal can be envisaged, for example with a secure location function involving two-way communication between the vehicle in question and a corresponding badge worn by a user.

[0024] In such a gesture detection system, optionally: - the transmission and reception module comprises at least a first radar antenna and a second radar antenna configured, each to transmit at least one transmitted radiofrequency signal and receive a return radiofrequency signal, and having respective sighting axes inclined at least 30° relative to each other; - the transmission and reception module is configured to transmit a continuous signal using said first radar antenna, and a pulsed signal using said second radar antenna, with the line of sight of said second radar antenna which is oriented along a substantially vertical axis, in use in a motor vehicle having its four wheels resting on a horizontal plane: - the data extraction unit is configured to receive as input data from said second radar antenna, and to extract therefrom the first data relating to a first range of distances to the second antenna, and the second data relating to a second range of distances to the second antenna; - the gesture detection unit is configured to receive said first data as well as data from the first radar antenna, and to deduce therefrom said information relating to the detection of the predetermined gesture; and - the calculator of the trunk opening management system is configured to receive said second data as input, and to deduce information therefrom relative to a current position of the opening.

[0025] According to a final aspect, a motor vehicle is provided with a trunk associated with a trunk opening movable between a position allowing access to the trunk from a space outside the vehicle and a closed position isolating an interior space of the trunk from the space outside the vehicle, characterized in that it comprises a trunk opening management system as defined above.

[0026] This vehicle may further comprise a motorized trunk opening device as well as a gesture detection device associated with said motorized trunk opening device. Brief description of the drawing

[0027] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawing showing various figures, in which: Fig. 1A

[0028] [Fig.lA] schematically shows a transmitted pulse signal and a return pulse signal that can be used in a method according to the present disclosure. Fig. 1B

[0029] [Fig.lB] schematically shows a pulse of transmitted pulse signal. Fig. 2

[0030] [Fig.2] schematically shows a pulse of a return pulse signal, sampled in time. Fig. 3

[0031] [Fig.3] schematically shows a matrix grouping values ​​relating to a plurality of pulses. Fig. 4

[0032] [Fig.4] schematically shows a motor vehicle trunk for implementing a method according to the present disclosure. Fig. 5

[0033] [Fig.5] schematically shows signal peaks corresponding to trunk opening positions and user foot detection. Description of the embodiments

[0034] The present disclosure relates to a system and a method for managing the opening of a trunk opening 140 of a motor vehicle 100 ([Fig.4]) and aims to determine the opening position (relative or absolute) of the trunk opening 140. This disclosure relates more particularly but not exclusively to a trunk 120 having a system for opening its motorized opening, said opening system being controlled for example by detecting a user's gesture.

[0035] It is particularly known to have a system which allows the detection of a user's foot passing under the rear of the vehicle. Such a system ([Fig.4]) most often uses a first radar antenna A1 and a second radar antenna A2, a radar antenna being a device for transmitting and / or receiving radiofrequency signals.

[0036] As schematically illustrated in [Fig. 4], for a vehicle trunk equipped with such a system, the radar antenna A1 is for example fixed under the trunk and has a viewing axis oriented at approximately 45° towards the ground. This radar antenna emits for example a continuous monofrequency signal. The radar antenna A2 is oriented to emit a signal perpendicular to the ground, that is to say most often a substantially vertical signal. This second antenna A2 is for its part configured to emit pulsed signals. The viewing axes of the antennas thus form an angle of 45° with each other here. This angle value depends on the emission solid angle of the antennas. To avoid an overlap of the information corresponding to the emissions of the two antennas, there will preferably be an angle of at least 30° between the two viewing axes of the radar antennas A1 and A2.

[0037] Such an opening system is for example provided with electronic processing means and comprises - a gesture detection unit, configured to receive as input data relating to said return signals, and to deduce therefrom information relating to the detection of a predetermined gesture, said gesture being intended to control the opening of an opening of the motor vehicle; - a transmission and reception module, including the radar antennas A1 and A2, configured to transmit a continuous signal using the first radar antenna A1, and a pulsed signal using the second radar antenna A2: - a data extraction unit, configured to receive as input data from the second radar antenna A2, and to extract therefrom first data relating to a first range of distances to the second antenna, and to further extract therefrom second data relating to a second range of distances to the second antenna; - the gesture detection unit is configured to receive said first data as well as data from the first radar antenna, and to deduce therefrom said information relating to the detection of the predetermined gesture. When it comes to controlling an opening of the opening from a gesture detection, the target is then a user's foot and otherwise the target can be the opening which allows access to the trunk of the vehicle from outside of it as well as its closing as explained below.

[0038] In the remainder of this description, the second antenna A2 will be discussed mainly and for this we will simply speak of a pulsed signal. transmitted and return pulse signal. We assume that the second antenna A2 is a transmitting and receiving antenna. In [Fig.lA], a curve 11, in solid lines, represents an intensity of the transmitted pulse signal as a function of time t. A curve 12, in dotted lines, represents an intensity of the return pulse signal as a function of time t.

[0039] [Fig.lB] illustrates in more detail one of the pulses of the transmitted pulse signal. Each pulse is defined by a carrier and an envelope. The carrier frequency, f2, belongs to the radio frequency spectrum. For example, the carrier frequency is equal to 7.8 GHz. The envelope is defined by a frequency spectrum, the highest value of which, fl, is much lower than f2. For example, fl less than or equal to f2 / 10. For example, fl is equal to 500 MHz.

[0040] Preferably, the emitted pulse signal is a signal modulated according to the modulation technique known as “UWB”, for “Ultra Wide Band”. This modulation technique is based on the transmission of pulses of very short duration, preferably less than one nanosecond, and over a wide frequency spectrum.

[0041] In the same way, the return pulse signal is constituted by pulses each defined by a carrier of frequency f2 and an envelope of higher frequency fl.

[0042] To determine the position of the opening, it is necessary to determine the distance separating the radar antenna A2 from the opening. Depending on the transmission carried out (either downwards only for a monodirectional antenna, or downwards and upwards for a bidirectional antenna) the electromagnetic wave emitted by the radar antenna A2 reaches the opening directly (after having passed through the bottom of the trunk) or is reflected on the ground before reaching the opening (passing through the bottom of the trunk).

[0043] To measure the distance (direct or with reflection) traveled by the emitted pulse signal, a measurement of a time shift between a pulse of the return pulse signal and the corresponding pulse of the emitted pulse signal is carried out. In particular, the time shift between the respective amplitude maxima of these two pulses is measured.

[0044] This involves in particular measuring a shift between a reception time tr and a transmission time tO, with: - tO the instant of emission by the emission and reception device (radar antenna A2) of a given pulse of the emitted pulse signal, and - the instant of reception by said device of the corresponding pulse of the return pulse signal.

[0045] Here, the return pulse signal is sampled in time by an analog-to-digital converter, preferably within the radar antenna A2. [Fig.2] schematically illustrates a pulse of the return pulse signal time-sampled.

[0046] The sampling frequency of the return impulse signal is denoted as f_samp. According to the Shannon criterion, the maximum value that f_samp can take is twice f2, that is, the highest frequency of the envelope of the return impulse signal, considered equal to the highest frequency of the emitted impulse signal, that is, f1. Thus, if we have f1 = 500 MHz, we will have a sampling frequency f_samp of 1 GHz.

[0047] The value of the sampling frequency f_samp determines a temporal sampling window width Atl associated with the temporal sampling of the return impulse signal, with: Atl = 1 / f_samp.

[0048] The value of Atl gives the margin of error on the determination of the time shift between a pulse of the return pulse signal and the corresponding pulse of the emitted pulse signal. By then considering the speed c of the signal, which is substantially the speed of light in a vacuum, i.e. 3 10exp8 m / s, we can obtain the spatial shift d_sp between the transmitter / receiver device, i.e. the radar antenna A2, and the target, i.e. the trunk opening. Just as there is a margin of error on the determination of the time shift, we obtain a margin of error Adl on the determination of a spatial shift. Here we will have: Adl=c / 2*f_éch A factor of 2 is introduced because the signal travels back and forth between the antenna and the target. With the previous numerical values, Adl is approximately equal to 15 cm.

[0049] The approximate distance d_sp measured therefore corresponds to the distance separating the radar antenna A2 from the trunk opening, with or without reflection on the ground depending on the direction of emission towards the ground or towards the trunk of the emitted pulse signal (if there is no other “reflecting” obstacle between them such as a user's foot) with a margin of error Adl.

[0050] [Fig.2] illustrates: - tO corresponding to the instant of emission of a pulse in an emitted pulse signal, - Atl corresponding to the width of a sampling window, and - FR corresponding to a time window receiving the pulse of the return pulse signal corresponding to the pulse of the pulse signal emitted at tO.

[0051] The instant t0 can be defined from a start instant of the emission of the pulses and a repetition frequency of the pulses. Alternatively, t0 can be defined from a reception instant, by the radar antenna A2, of a signal of (very) high intensity. The latter corresponds to a part of the pulse of the emitted pulse signal which is detected directly by the radar antenna A2, without having been reflected by the target.

[0052] The determination of the distance d_sp can be carried out by constituting a matrix with the data, as illustrated in [Fig.3]. This matrix is ​​a 3D matrix with: - a first dimension k corresponding to the count of the pulses of the emitted pulse signal, where each emission of a new pulse increments by one unit the value of the index k; - a second dimension, i, corresponding, for each index k, to the time axis divided into sampling windows; and - a third dimension, called S(k,i), corresponding to the absolute value of the amplitude of the signal measured by the radar antenna A2, where appropriate after application of at least one filter to overcome the noise.

[0053] The first dimension and the second dimension together correspond to a folding of the time axis to define a new origin of times at each new emission of a pulse of the emitted pulse signal. This folding of the time axis makes it possible to obtain directly, by identifying the time window receiving an amplitude peak of the signal, the sought time shift (and therefore also the spatial shift d_sp).

[0054] [Fig.4] illustrates a vehicle 100 comprising a trunk 120 and a trunk opening 140 shown in dotted lines in three distinct positions: closed, half-open and fully open. This very schematic figure also shows the radar antenna A1 and the radar antenna A2.

[0055] As illustrated in [Fig.4], the radar antenna A2 measures a distance between itself and the trunk opening which is equal to: - DI when the trunk is closed (trunk opening 120 locked for example); - D2 when the trunk opening 140 is in an intermediate position (trunk half-open); and - D3 when the trunk opening 140 is in a maximum opening position.

[0056] An original idea for measuring the position of the trunk opening 140 is to isolate, from the return pulse signals, the part of the signal which will make it possible to determine the position of the trunk opening 140.

[0057] It is then proposed to carry out a preliminary calibration operation. This operation can be carried out once and for all for the same type of vehicle (same geometry of trunk and opening, same radar antenna A2). Here it is appropriate to determine the values ​​of DI and D3. This determination can be made by simulation or during calibration with a prototype. The distance between the radar antenna A2 and the ground varies very little.

[0058] If the radar antenna A2 only transmits towards the ground, it will be necessary to take into account reflection conditions which may differ from one measurement to another.

[0059] If the radar antenna A2 is bidirectional, it will be advantageous to arrange it so that it is closer to the ground than to the trunk opening in its closed position. The idea here is to clearly distinguish the return pulse signals having reached the trunk opening 140 from those which have reached another target. In the case of a pulse signal emitted towards the ground, a target which would be between the ground and the trunk 120 will necessarily correspond to a distance d_sp less than that of the closed trunk (Dl). By placing a bidirectional radar antenna A2 in the “low” position, that is to say closer to the ground than to the trunk opening 140 in the closed position, it is also ensured that a peak of the return pulse signal corresponding to the trunk opening 140 can be distinguished from a peak of the return pulse signal corresponding to a target (foot of a user wishing to open the trunk) arranged between the ground and the radar antenna A2.

[0060] For a radar antenna A2 mounted in a given vehicle, the values ​​of i (see [Fig.3]) corresponding to D1 and D3, respectively il and i3, are then defined during the calibration operation. The calibration operation may consist of determining the values ​​il and i3.

[0061] Thus, when carrying out a measurement to know the position of the trunk opening 140, a data matrix such as that of [Fig.3] is constructed within an electronic unit integrating a computer (or microprocessor) and a memory capable of recording, for example, data corresponding to the emitted pulse signals and to the return pulse signals to be analyzed. (Electronic) analysis means are then provided to detect the presence of a peak for pulses for index values ​​i between i1 (inclusive) and i3 (inclusive). If a peak is detected between these two values ​​i1 and i3 inclusive, then it is considered that it is a peak originating from a return pulse signal resulting from a reflection on the trunk opening 140. It is appropriate to determine the index corresponding to this peak: then i2 is said index.

[0062] The electronic means for determining the opening of the trunk opening can be integrated into a radar antenna (A2 and / or A1) or can be located in an electronic unit separate from the antennas, for example an electronic vehicle control and management unit.

[0063] To determine the proportion of opening of the trunk %_ouv, we can for example use the formula: %_ouv=(i2-i 1 ) / (i3-i 1 )* 100

[0064] [Fig.5] schematically illustrates various peaks that can be observed during a trunk opening measurement.

[0065] On the abscissa axis, the index i of [Fig.3] has been plotted. On this axis, a value i_lim is provided. In this variant, it is provided in the analysis of the matrix obtained to analyze the peaks observed for i>i_lim. Advantageously, an upper limit i_sup is also determined.

[0066] If a peak is observed for i=i0 <i_lim, alors on considère que ledit pic ne peut pas correspondre à une valeur d’ouverture d’ouvrant de coffre.

[0067] The values ​​il and i3 correspond to the values ​​il and i3 previously defined. We will have: i_lim<=il and i_lim <i3.

[0068] When a peak corresponding to an index i2 (with i2>=i_lim and il<=i2<=i3) is detected, the peak corresponding to this index i2 is considered to result from a reflection on the trunk opening 140 and the proportion of opening of the trunk %_ouv will then be determined.

[0069] As mentioned above, the signal from the radar antenna A2 can also be used for a function other than the function described above of determining the position of the opening 140. The data extraction unit, thanks to the calibration operation, will be able to distinguish the parts of the return signals which are relative to the position of the opening and the parts of these signals relative to another function. This other function can be the gesture detection mentioned above but it can also be obstacle detection, two-way communication with a badge, etc.

[0070] It is possible to provide for the functions of detecting the opening of an opening and of detecting gestures to have an omnidirectional emission / reception with a UWB type signal, a directional reception then being used for the detection of a proportion of opening of the trunk opening (or other opening).

[0071] While as described, the signal emitted by the radar antenna A2 is a pulsed signal, the signal emitted by the radar antenna A1 can be a continuous signal. We can then have for the radar antenna A1 and for the radar antenna A2 a directional emission / reception of a continuous wave (or in English "continuous wave" or CW) respectively a directional emission / reception of a pulsed wave (of the UWB type). A part of the return signals from the pulsed radar antenna A2 can then be used for gesture detection (corresponds to a detection "close" to the antenna) and another part is used for determining the position of an opening.The combination of the analysis of the signals received in return by the radar antenna A2 in combination with the analysis of the signals received in return by the radar antenna A1 is used by the electronic processing means to carry out a detection of a movement, for example of a movement of a user's foot, with a view to controlling an opening of an opening in a manner known to those skilled in the art. Industrial application

[0072] The present disclosure therefore proposes in an original manner to use a transmitter-receiver device to carry out detection of a proportion of opening of an opening, for example of a trunk, rather than using a sensor on an opening actuator.

[0073] This is particularly interesting on a vehicle equipped with a gesture detection device used to control the opening of the relevant opening, in particular the trunk. Indeed, such a gesture detection device is conventionally equipped with a radar antenna which is then also used in an original manner for measuring the distance between said radar antenna and the corresponding trunk opening.

[0074] Furthermore, the use of pulsed signals (commonly known by the English acronym UWB) makes it possible to avoid providing an additional radar antenna which is used solely for measuring the opening of the trunk, but to use an antenna already present in the vehicle for other functions (detection of gestures and / or secure location implementing two-way communication between the vehicle and a badge worn by a user).

[0075] The information on the opening of the trunk opening can then be used by a motorized trunk opening control device. It is known in particular to detect an obstacle. Once the obstacle is detected, a maximum opening of the opening can be determined. The power supply to the opening control motor will then be cut off as soon as the determined maximum opening is reached.

[0076] The measurement can be carried out with a monodirectional radar antenna but is preferably implemented with a bidirectional radar antenna, or even with transmission using an omnidirectional radar antenna coupled with reception using a directional radar antenna.

[0077] The method proposed here in an original manner is to only be interested in a part of a return pulse signal which may correspond to the information sought on the opening of the opening and not to take into account the rest of this signal. The relevant part of the signal is determined during a prior calibration step.

[0078] The invention, based on the use of a pulsed radiofrequency signal, makes it possible to share resources with at least one other device such as a gesture detection device. Advantageously, this sharing is made possible by a data extraction unit, configured isolated from the return signal portions associated with one or other range of distances to the vehicle.

[0079] The method can be applied to any type of vehicle. It is more particularly intended for vehicles with a motorized trunk opening, but other applications on vehicles without a motor for opening the trunk opening can be envisaged.

[0080] The present disclosure is not limited to the exemplary embodiments and variants described above, only as examples, but it encompasses all variants which the person skilled in the art may consider within the framework of the protection sought.

Claims

Claims

1. Method for determining a position of a trunk opening (140) of a vehicle (100), the vehicle comprising a radar antenna (A2) configured and positioned so as to emit a pulse signal along a line of sight, the line of sight being oriented in a substantially vertical direction when the vehicle has its wheels resting on a horizontal plane, the method being characterized in that it comprises the following steps: -a- emission of at least one transmitted pulse signal, -b- reception of at least one return pulse signal, -c- measurement of a time difference between a pulse of the return pulse signal considered and a corresponding pulse of the transmitted pulse signal, -d- estimation of a distance corresponding to the measured time difference, knowing the speed of the signal, -e- if the estimated distance is included in a range of possible distances that can separate the radar antenna and the trunk opening,then it is considered to be the distance separating the radar antenna from the trunk opening.,

2. Method according to claim 1, characterized in that the radar antenna (A2) is a bidirectional antenna.

3. Method according to one of claims 1 or 2, characterized in that the radar antenna (A2) is arranged closer to the ground than to the trunk opening (140) in the closed position.

4. Method according to one of claims 1 to 3, characterized in that it comprises a prior step for determining by calculation or by measurements a range of possible distances which can separate the radar antenna (A2) and the trunk opening (140).

5. Method according to one of claims 1 to 4, characterized in that the return pulse signal is sampled in time by an analog-digital converter.

6. Method according to one of claims 1 to 5, characterized in that it further comprises a step of determining the relative opening of the trunk opening (140).

7. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to implement steps -c- and following of a method according to one of the claims- indications 1 to 6.

8. Computer intended to be installed in a motor vehicle comprising at least one processor and at least one memory, characterized in that it is configured for the implementation of steps -c- and following of a method according to one of claims 1 to 6.

9. Trunk opening management system intended to be installed in a motor vehicle, characterized in that it comprises: - a transmission and reception module comprising at least one radar antenna (A2), and configured to transmit and receive a pulsed radiofrequency signal, and - an electronic management module comprising a computer according to claim 8.

10. Trunk opening management system according to claim 9, characterized in that the radar antenna (A2) of the transmission and reception module is intended to transmit omnidirectionally, and in that the system further comprises at least one directional antenna intended to receive directionally.

11. Gesture detection system for a motor vehicle, comprising: - a trunk opening management system according to claim 9 or 10; - a data extraction unit, configured to receive as input data from the transmission and reception module relating to a pulsed radiofrequency signal received by said module, and to extract therefrom first data relating to a first range of distances to the radar antenna of the transmission and reception module, and to further extract therefrom second data relating to a second range of distances to the radar antenna of the transmission and reception module;- a gesture detection unit, configured to receive as input data relating to at least one radiofrequency signal received by the transmission and reception module of the trunk opening management system, and to deduce therefrom information relating to the detection of a predetermined gesture, said gesture being intended to control the opening of an opening of the motor vehicle, said data relating to at least one received radiofrequency signal comprising at least said first data, extracted by the data extraction unit; and in which the computer of the trunk opening management system is configured to use said extracted second data; by the data extraction unit.

12. Gesture detection system according to claim 11, wherein: - the transmission and reception module comprises at least a first radar antenna and a second radar antenna configured, each to transmit at least one transmitted radiofrequency signal and receive a return radiofrequency signal, and having respective sighting axes inclined at least 30° relative to each other;- the transmission and reception module is configured to transmit a continuous signal using said first radar antenna, and a pulsed signal using said second radar antenna, with the line of sight of said second radar antenna which is oriented along a substantially vertical axis, in use in a motor vehicle having its four wheels resting on a horizontal plane: - the data extraction unit is configured to receive as input data from said second radar antenna, and to extract therefrom the first data relating to a first range of distances to the second antenna, and the second data relating to a second range of distances to the second antenna; - the gesture detection unit is configured to receive said first data as well as data from the first radar antenna, and to deduce therefrom said information relating to the detection of the predetermined gesture;and - the calculator of the trunk opening management system is configured to receive said second data as input, and to deduce therefrom information relating to a current position of the opening.;

13. Motor vehicle provided with a trunk associated with a trunk opening movable between a position allowing access to the trunk from a space outside the vehicle and a closed position isolating an interior space of the trunk from the space outside the vehicle, characterized in that it comprises a trunk opening management system according to one of claims 9 or 10.

14. Motor vehicle according to claim 13, characterized in that it comprises a motorized trunk opening device as well as a gesture detection device associated with said motorized trunk opening device.

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