Method for determining presence in a vehicle, particularly in a trunk

Abstract

Method for determining a presence in a vehicle trunk, the vehicle comprising a radar antenna 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 is resting on a horizontal plane, the method being characterized in that it comprises the following steps: -a- emission of at least one emitted pulse signal, -b- reception of at least one return pulse signal, -c- filtering the return pulse signal to retain a dynamic component of said signal, -d- measurement of the amplitude of the return pulse signal filtered on a portion of this signal corresponding to a reflection of the emitted pulse signal after having traveled at least a predetermined distance, -e- detection of a presence when the measured amplitude is greater than an amplitude predetermined beforehand by calibration. Abstract figure: Figure 4

Description

Title of the invention: Method for determining presence in a vehicle, in particular in a trunk

[0001] The present disclosure relates to a method for determining presence in a vehicle, in particular in a trunk. Technical field

[0002] The present disclosure relates to the field of access management to a motor vehicle and more particularly to the trunk of this vehicle. Most often, a trunk is located at the rear of a vehicle but can also be located at the front of the vehicle. Thus, the present disclosure relates to a trunk placed at the rear as well as at the front of 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] In particular, there are 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 in time by an analog-to-digital converter. The frequency of the time 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 measurement precision, the sampling frequency must be as high as possible. In practice, a precision of of the order of ten centimeters, for example between 10 and 20 cm, for example around 15 cm.

[0007] There are more and more motorized openings on a vehicle, most often trunk doors. With a gesture detection system, it is then possible to control, for example, by a gesture of the foot at a predetermined location, the opening, and sometimes also the closing, of the trunk door. When the closing of the trunk door is controlled by a gesture, it must be ensured that when closing, said door will not hit a person, for example someone who is busy in the trunk to arrange or remove belongings. A specific sensor, for example a Doppler effect sensor, can then be provided to detect a presence and, in cooperation with an opening control system, prevent the opening from closing if a presence is detected. Summary

[0008] The original idea behind the present disclosure is to integrate into the gesture detection system used to control the opening and / or closing of the trunk the function of detecting a presence in the trunk instead of entrusting it to an external system such as a Doppler radar or other.

[0009] A method is proposed for determining a presence in a vehicle trunk, the vehicle comprising a radar antenna configured and positioned so as to emit a transmitted pulsed radar signal and to receive a return pulsed radar signal, with said return pulsed radar signal oriented along a line of sight, the line of sight being oriented in a substantially vertical direction when the vehicle is resting on a horizontal plane. Said vehicle trunk may be located at the rear or at the front of the vehicle concerned.

[0010] According to the present disclosure, this method comprises the following steps: -a- emission of at least one pulsed radar signal emitted, in particular in the direction of the trunk of the vehicle, -b- reception of at least one return pulse radar signal, corresponding to the reflection on a target of the emitted pulse radar signal, -c- measurement of the amplitude of the return pulse signal filtered on a portion of this signal corresponding to a reflection of the pulse signal emitted after having traveled at least a predetermined distance, -d- detection of a presence when the measured amplitude is greater than an amplitude predetermined beforehand by calibration.

[0011] To implement such a method, it is possible to consider using: - either a directional antenna which emits downwards and exploits the reflection of the radar signal on the ground; - either a bidirectional antenna which emits upwards (for presence detection) and downwards (for gesture detection); - either a multidirectional antenna for transmitting, as well as a directional antenna oriented vertically for receiving.

[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 return pulsed radar signal is filtered to retain only one component dynamics of said return pulsed radar signal;

[0014] - the return pulsed radar signal is time sampled by a analog to digital converter;

[0015] - the portion of signal used for the amplitude measurement in step -c- is associated with a distance between the radar antenna and the target which is between said predetermined lower threshold and a predetermined upper threshold, together defining a range of distances to the radar antenna; in this case, it can then be provided that the method further comprises a preliminary calibration step during which: -Cl- said predetermined lower and upper thresholds are determined, together defining a range of distances to the radar antenna as a function of a geometry of the trunk, -C2- a noise measurement is carried out with an empty trunk for a predetermined time interval, and using portions of return pulsed radar signal associated with said range of distances to the radar antenna, and an average noise is determined, on the one hand, in the form of a vector on the portion of signal considered and, on the other hand, a standard deviation of the noise in the form of a vector on the portion of signal considered, and -C3- a detection threshold is determined from the measured average noise and the standard deviation of the noise.

[0016] 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.

[0017] 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.

[0018] According to another aspect, there is provided a system for detecting presence in a trunk 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 at least said transmitted pulsed radar signal and to receive at least said return pulsed radar signal, the return pulsed radar signal being oriented substantially vertically when the vehicle is resting on horizontal ground, and - an electronic management module comprising a computer as defined above.

[0019] According to an alternative embodiment, in this system for detecting presence in a trunk, the radar antenna of the transmission and reception module is configured to transmit unidirectionally, in the direction of the ground when the vehicle is resting on a horizontal plane ground.

[0020] According to another aspect, there is provided a gesture detection system for a motor vehicle, comprising: - a system for detecting presence in a trunk 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 as input data relating to at least one radiofrequency signal received by the transmission and reception module of the system for detecting presence in a trunk, 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 wherein the calculator of the trunk presence detection system is configured to use said second data extracted by the data extraction unit.

[0021] The production of such a gesture detection system is particularly advantageous because it pools resources between the functions of detecting presence in the trunk and of detecting gestures. 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. A pooling of the presence detection 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.

[0022] 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 (for example between -30° and +30°, or preferably between -15° and +15° if the vertical corresponds to 0°), in use in a motor vehicle 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 a predetermined gesture; and - the calculator of the system for detecting presence in a trunk is configured to receive said second data as input, and to deduce therefrom information relating to a detection of presence in the trunk.

[0023] According to a final aspect, there is provided a 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 system for detecting presence in said trunk as defined above.

[0024] 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 drawings

[0025] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which: Fig. 1A

[0026] [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

[0027] [Fig.lB] schematically shows a pulse of transmitted pulse signal. Fig. 2

[0028] [Fig.2] schematically shows a pulse of a return pulse signal, time-sampled. Fig. 3

[0029] [Fig.3] schematically shows a matrix grouping values ​​relating to a plurality of pulses. Fig. 4

[0030] [Fig.4] schematically shows a motor vehicle trunk for the storage implementation of a method according to the present disclosure. Fig. 5

[0031] [Fig.5] schematically shows signal peaks corresponding to a presence in a trunk and a detection of a user's foot. Description of the embodiments

[0032] The present disclosure relates to a system and a method for detecting presence in a trunk 120 of a motor vehicle 100 ([Fig.4]) and aims to determine a (partial) presence in this trunk of a person, for example detecting an arm, a head, a trunk, etc. 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. [Fig.4] illustrates a rear trunk of a vehicle but the following description can also apply to a trunk arranged at the front of a vehicle.

[0033] 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.

[0034] As illustrated schematically in [Fig. 4], for a motor vehicle trunk equipped with such a system, the radar antenna A1 is for example fixed under the trunk and has a line of sight oriented at approximately 45° towards the ground. This radar antenna emits for example a continuous single-frequency 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 configured to emit pulsed signals. The lines of sight of the antennas therefore form here between them an angle of 45°. This angle value depends on the solid angle of emission 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 lines of sight of the radar antennas A1 and A2.

[0035] Such an opening system is for example equipped 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 or closing of a trunk 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.

[0036] When it comes to controlling an opening of the trunk opening from a detection of a gesture, the target is then a user's foot and otherwise the target can be another part of the body of a user of said trunk, as well as its closing as explained below.

[0037] In the remainder of this description, the second antenna A2 will be mainly discussed and for this we will simply speak of the transmitted pulse signal and the returned pulse signal. It is assumed that the second antenna A2 is a transmitting and receiving antenna. In [Fig. 1A], 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 returned pulse signal as a function of time t.

[0038] [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.

[0039] 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.

[0040] In the same way, the return pulse signal is made up of pulses each defined by a carrier of frequency f2 and an envelope of higher frequency fl.

[0041] To determine the position of a target, it is necessary to determine the distance separating the radar antenna A2 from the target. Depending on the emission carried out (either downwards only for a monodirectional antenna, or downwards and upwards for an omnidirectional antenna) the electromagnetic wave emitted by the radar antenna A2 reaches the target directly or is reflected on the ground before reaching the target (which may be the foot controlling the opening / closing of the trunk or an arm or similar in the trunk 120).

[0042] 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.

[0043] This involves in particular measuring a shift between a reception time tr and a transmission time tO, with:

[0044] - tO the instant of transmission by the transmission and reception device (radar antenna A2) of a given pulse of the emitted pulse signal, and

[0045] - tr the instant of reception by said device of the corresponding pulse of the signal impulse return.

[0046] Here, the return pulse signal is time-sampled by an analog-to-digital converter, preferably within the radar antenna A2. [Fig.2] schematically illustrates a pulse of the return pulse signal sampled in time.

[0047] The sampling frequency of the return pulse signal is denoted f_éch. According to the Shannon criterion, the minimum value that f_éch can take is twice f2, that is to say the highest frequency of the envelope of the return pulse signal, considered as equal to the highest frequency of the emitted pulse signal, that is to say fl. Thus, if we have fl=500 MHz, we will have a sampling frequency f_éch equal to 1 GHz.

[0048] The value of the sampling frequency f_éch sets a width Atl of sampling time window associated with the time sampling of the return pulse signal, with:

[0049] Atl=l / f_ech.

[0050] The value of Atl gives the margin of error in determining the time shift between a pulse of the return pulse signal and the corresponding pulse of the transmitted pulse signal. 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. Just as there is a margin of error in determining the time shift, we obtain a margin of error Adl in determining a spatial shift. Here we will have:

[0051] Adl=c / 2*f_ech

[0052] A factor of 2 is introduced because the signal makes a round trip between the antenna and the target.

[0053] With the previous numerical values, Adl is substantially equal to 15cm.

[0054] The approximate distance d_sp measured therefore corresponds to the distance separating the radar antenna A2 from the target, with or without reflection on the ground depending on the target, 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.

[0055] [Fig.2] illustrates:

[0056] - tO corresponding to the instant of emission of a pulse in a signal emitted impulse,

[0057] - Atl corresponding to the width of a sampling window, and

[0058] - FR corresponding to a time window receiving the signal pulse return pulse corresponding to the pulse of the pulse signal emitted at tO.

[0059] 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.

[0060] 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:

[0061] - a first dimension k corresponding to the count of the signal pulses emitted pulse, where each emission of a new pulse increments the value of the index k by one unit;

[0062] - a second dimension, i, corresponding, for each index k, to the time axis cut into sampling windows; and

[0063] - 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.

[0064] 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 allows to obtain directly, by identifying the time window receiving a peak of amplitude of the signal the sought time shift (and therefore also the spatial shift d_sp).

[0065] [Fig.4] illustrates a vehicle 100 comprising a trunk 120 and a trunk opening. 140 shown in dotted lines in two distinct positions: closed and fully open. This very schematic figure also shows the radar antenna Al and the radar antenna A2.

[0066] As illustrated in [Fig.4], the radar antenna A2 measures a distance between itself and a target (illustrated by a cross) in the trunk. It is assumed here that the radar antenna A2 is unidirectional and oriented towards the ground on which the vehicle 100 is resting. In this figure we have:

[0067] - dl which corresponds to the distance separating the radar antenna A2 from the ground on which the vehicle is leaning;

[0068] - d2 which corresponds to the distance traveled by a wave emitted by the radar antenna A2 until it reaches a target in chest 120 after reflection on the ground. We therefore have d2>dl (and even d2>2*dl).

[0069] An original idea for detecting the presence of a target in the trunk 120 is to isolate, from the return pulse signals, on the one hand, the part of the signal for detecting the presence of a foot, and, on the other hand, the part of the signal which will make it possible to determine the presence of a target in the trunk 120.

[0070] 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 trunk and opening geometry, same radar antenna A2). Here it is appropriate to determine limit values ​​for d2. Let da and db be respectively the lower limit for d2 and the upper limit for d2. This determination can be made by simulation or during calibration with a prototype. The distance dl between the radar antenna A2 and the ground varies very little.

[0071] 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.

[0072] If the radar antenna A2 is omnidirectional, it will be advantageous to position it so that it is closer to the ground than to a target in the trunk. The idea here is to clearly distinguish the return pulse signals that have reached a target in the trunk 120 from those that have reached another target. In the case of a pulse signal emitted towards the ground, a target that is between the ground and the trunk 120 will necessarily correspond to a distance less than dl. By placing an omnidirectional radar antenna A2 in a “low” position, that is to say closer to the ground than to the bottom of the trunk 120, it is also ensured that a peak of the return pulse signal corresponding to a target in the trunk 120 can be distinguished from a peak of the signal return pulse corresponding to a target (foot of a user wishing to open the trunk) placed between the ground and the A2 radar antenna.

[0073] It will be assumed subsequently that the radar antenna A2 is unidirectional. It then emits a radiofrequency signal in a cone whose apex is located at the level of the radar antenna A2 and with an angle at the apex sufficient for the waves reflected on the ground to cover at least the greater part of the volume of the trunk 120.

[0074] For a radar antenna A2 mounted in a given vehicle, we then define during the calibration operation values ​​i of Tap_Num (see [Fig.3]) corresponding to the interval between da and db. Let ia then be the value of Tap_Num from [Fig.3] for the distance da and ib the equivalent value for db.

[0075] The calibration operation described here also proposes to determine a signal amplitude threshold (ICIRI in [Fig.3]) from which it is appropriate to estimate that there is a presence in the trunk of the vehicle. When the trunk is empty and a signal is emitted, a signal of low but non-zero amplitude is obtained in return, corresponding to “ambient noise” linked to the antenna and the environment.

[0076] A calibration is then carried out with the antenna on the interval [da, db] or its equivalent [ia, ib].

[0077] Either: i a value of Tap_Num; CIR_tap_i the amplitude of the signal for i N_CIR_index a number of signals emitted / returned: if a signal is emitted every millisecond, with N_CIR_index equal to 100, the measurement will be carried out over 100 ms.

[0078] We then calculate an average noise, classically called “Offset” for each value i of the interval [ia, ib]: Offset (tap_i) = Average (CIR_tap_i) on N_CIR_index i.e. for N_CIR_index signals we take the average of the amplitudes measured on a return signal for the value i of Tap_Num.

[0079] We do the same operation for the standard deviation of the amplitude measurements carried out: standard_deviation (tap_i) = standard_deviation (CIR_tap_i) on N_CIR_index

[0080] The values ​​Offset (tap_i); CIR_tap_i); standard_deviation (tap_i) for I varying from ia to ib are arranged for example in a matrix.

[0081] From this matrix, we determine a vector corresponding to the amplitude threshold from which we estimate that there is a presence in the observed volume, here the trunk of the vehicle. We will take for example: minimum_threshold (tap_i) = offset (tap_i) + 6 * standard_deviation (tap_i)

[0082] This formula is proposed here but another threshold vector can be chosen depending on the sensitivity that one wishes to give to the detection system.

[0083] Thus, when detecting a presence in the trunk 120, 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 the return pulse signals to be analyzed. It should be noted that the return pulse signals are filtered to remove any continuous component so that only the dynamic part of the return pulse signal is considered here. (Electronic) analysis means are then provided to detect the presence of a peak for pulses for index values ​​i between ia (inclusive) and ib (inclusive). If a peak is detected between these two values ​​ia and ib inclusive, then it is considered to be a peak originating from a return pulse signal resulting from a reflection on a target located in the trunk 120.

[0084] The electronic means for detecting presence in the trunk 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.

[0085] [Fig.5] schematically illustrates various peaks that can be observed during a presence detection measurement in the trunk 120.

[0086] On the abscissa axis, the index i of [Fig.3] has been plotted. On this axis, a value i is provided. In this variant, it is provided in the analysis of the matrix obtained to analyze the peaks observed for i ​

[0087] The vehicle comprises an electronic control and management unit for opening and closing the trunk in the case of a motorized trunk opening. This electronic unit is connected to the gesture detection system also including the detection of presence in the trunk. When a foot gesture to control opening or closing of the trunk opening is detected, when a presence is detected in the trunk, a corresponding signal is sent, for example to separate inputs (one input for the opening signals, one for closing and one for presence detection).Programming of the electronic control and management unit can then advantageously provide that if a presence is detected in the trunk and a trunk opening closing command signal is received simultaneously or within a predefined time interval, priority will then be given to the presence detection and the closing command will be cancelled or delayed.

[0088] Such a situation may occur, for example, when a person is storing belongings in the trunk of their car. They may be stamping near the trunk while their arms are moving in the trunk to store and / or move belongings. Stamping may be interpreted as a command to close the trunk opening, and it is then advisable to avoid closing the trunk so that the opening does not hit the person standing near the trunk.

[0089] The signal from the radar antenna A2 can also be used for a function other than the function described above of determining a presence in the trunk 120. The data extraction unit, thanks to the calibration operation, will be able to distinguish the parts of the return signals which are related to a presence in the trunk and parts of these signals related 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.

[0090] For the functions of detecting presence in the trunk and detecting gestures, it is possible to provide omnidirectional transmission / reception with a UWB type signal, directional reception then being used for detecting a presence in the trunk (or other volume).

[0091] 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

[0092] It is already known to have two antennas in a gesture detection system for controlling an opening, in particular a trunk opening, in the context of hands-free access to a vehicle. In a known manner, there is then an antenna observing, for example, towards the rear of the vehicle (assuming the latter is resting on a horizontal plane ground) with an orientation of approximately 45° downwards relative to a vertical. Another antenna is oriented vertically to observe the ground.

[0093] It is chosen here in an original manner to use for the vertically oriented antenna an antenna of the pulsed radar antenna type, for example of the UWB type. This antenna then makes it possible to have information on the distance separating the radar antenna from a detected target and thus to discriminate a gesture of the foot which would be at ground level (in the figures, the distance between the target and the antenna is less than dl) from a hand or other part of the body of a person (or an animal) which would come to interact in the trunk (distance from the antenna to the target greater than dl and preferably included in the example described between da and db.

[0094] The system for implementing the presence detection method according to the present disclosure may comprise: - either a ground-oriented radar antenna of the unidirectional type (therefore emitting according to an emission cone) for which the reflection on the ground makes it possible to detect what is happening inside the trunk; - either an omnidirectional radar antenna (therefore also partially oriented towards the ground) which will naturally detect what is happening inside the trunk. Here the position of the antenna is chosen to allow discrimination between a target between the antenna and the ground and a target in the trunk.

[0095] The principle of detecting the presence of a person (or a part of a person's body) interacting in the trunk of the vehicle is based on a template, i.e. it must be considered that the (part of the) person is more or less close to the pulse radar antenna (A2 in the figures). Two distances da and db are then defined (db can be very large). A threshold (Th in [Fig.5]) is also defined - in the form of a preference vector - which, when exceeded, indicates that there is an interaction in the trunk.

[0096] The present disclosure is not limited to the examples of method and system described above, only as examples, and to the variants mentioned, but it encompasses all the variants that may be envisaged by those skilled in the art within the framework of the protection sought.

Claims

Claims

1. Method for determining a presence in a vehicle trunk, the vehicle comprising a radar antenna configured and positioned so as to emit a transmitted pulse radar signal and to receive a return pulse radar signal, with said return pulse radar signal oriented along a line of sight, the line of sight being oriented in a substantially vertical direction when the vehicle is resting on a horizontal plane, the method being characterized in that it comprises the following steps: -a- emission of at least one transmitted pulse radar signal, in particular in the direction of the vehicle trunk, -b- reception of at least one return pulse radar signal, corresponding to the reflection on a target of the transmitted pulse radar signal, -c- measurement of the amplitude of the filtered return pulse radar signal, on a portion of this signal associated with a distance between the radar antenna and the target greater than a predetermined lower threshold,-d- detection of a presence when the measured amplitude is greater than an amplitude predetermined beforehand by calibration.,

2. Method according to claim 1, characterized in that the return pulse radar signal is filtered to retain only a dynamic component of said return pulse radar signal.

3. Method according to claim 1 or 2, characterized in that the return pulsed radar signal is time sampled by an analog-digital converter.

4. Method according to one of claims 1 to 3, characterized in that the portion of signal used for the amplitude measurement in step -c- is associated with a distance between the radar antenna and the target which is between said predetermined lower threshold and a predetermined upper threshold, together defining a range of distances to the radar antenna.

5. Method according to claim 4, characterized in that a preliminary calibration step is provided during which: -Cl- said predetermined lower and upper thresholds are determined, together defining a range of distances to the radar antenna, as a function of a geometry of the trunk, -C2- a noise measurement is carried out with an empty trunk, during a predetermined time interval, and using portions of return pulse radar signal associated with said range of distances to the radar antenna, and on the one hand, an average noise is determined in the form of a vector on the portion of return pulse radar signal considered and, on the other hand, a standard deviation of the noise in the form of a vector on the portion of return pulse radar signal considered, and -C3- a detection threshold is determined from the measured average noise and the standard deviation of the noise.

6. Computer program comprising instructions which, when the program is executed by a computer, cause the latter to implement steps -c- and following of a method according to one of claims 1 to 5.

7. 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 5.

8. System for detecting presence in a trunk 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 at least said transmitted pulsed radar signal and to receive at least said return pulsed radar signal, the return pulsed radar signal being oriented substantially vertically when the vehicle is resting on a horizontal plane ground, and - an electronic management module comprising a computer according to claim 7.

9. System for detecting presence in a trunk according to claim 8, characterized in that the radar antenna (A2) of the transmission and reception module is configured to transmit unidirectionally, in the direction of the ground when the vehicle is resting on horizontal flat ground.

10. Gesture detection system for a motor vehicle, comprising: - a system for detecting presence in a trunk according to claim 8 or 9; - 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 presence detection system, and to deduce therefrom information relating to the detection of a predetermined gesture, said gesture being intended to control the opening and / or closing of a trunk 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; in which the computer of the trunk presence detection system is configured to use said second data extracted by the data extraction unit and to inhibit closing of the trunk opening if a presence has been detected in the trunk by the presence detection system.;

11. Gesture detection system according to claim 10, 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 sighting axis of said second radar antenna being oriented along a substantially vertical axis, in use in a motor vehicle 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 a predetermined gesture; and - the computer of the system for detecting presence in a trunk is configured to receive said second data as input, and to deduce therefrom information relating to a presence in the trunk.

12. Motor vehicle equipped 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 system for detecting presence in said trunk according to one of claims 8 or 9.

13. Motor vehicle according to claim 12, 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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