Method for activating a vehicle function and associated device

Abstract

The invention relates to a method for activating a function of a vehicle from a "hands-free" access device (SD) carried by a user (U) by means of an activation device (D), the activation of the function being triggered by detecting a pressing of the user on a contact surface (S) of the vehicle and depending on the result of authentication of the device, the device comprising at least one transceiver (EM1), the invention relates to a method for transmitting a wave to a device, said device being located below a contact surface (S) and being able to communicate with said device via ultra wide band (UWB), comprising the following steps: a) transmitting a wave to said device, b) receiving a reflected wave, c) comparing, during a predetermined time length ([Delta] T), i) comparing the value of the phase ([phi]) of the reflected wave with a predetermined phase value distribution, said distribution exhibiting a phase rotation, and ii) comparing the value of the amplitude (A) of the reflected wave with a predetermined distribution of amplitude values, said distribution exhibiting an amplitude increase, d) detecting a pressing force of the user on the contact surface as a function of the result of said comparison, e) activating the vehicle function in the event of detecting the pressing force.

Description

[Technical field]

[0001] The invention relates to the field of motor vehicles and more particularly to a method for activating a function of a motor vehicle and to an associated device. The invention is particularly applicable to the function of locking and unlocking the doors of a motor vehicle. [Background Technology]

[0002] In motor vehicles, it is known to use presence detection devices to detect the presence of a hand or foot of a vehicle user, thereby allowing the locking or unlocking of all or some of the vehicle hatches (hatch here means passenger door, trunk lid, front hood where appropriate and possibly even hood). By way of example, the detection of the presence of a user's hand on or in front of a door handle, coupled with an identifier identifying a "hands-free" access device carried by the user, allows the locking and unlocking of these hatches.

[0003] For this purpose, when the user approaches the vehicle, communication is established between an access device (eg an electronic key card or a mobile phone) and a detection device via a wireless communication link in order to authenticate the access device using its identifier.

[0004] To this end, the detection device comprises an antenna allowing reception of the identifier sent by the access device.The detection device is connected to an electronic control unit (ECU) of the vehicle, to which ECU it transmits the identifier.

[0005] In the prior art, the access device is usually an electronic key card. A signal containing an identifier of the access device received by the antenna of the detection device is transmitted via radio frequency (RF) or low frequency (LF) waves.

[0006] However, it is now increasingly common to use a mobile phone to perform authentication functions, which makes it possible to avoid the use of dedicated electronic key cards, thus limiting the number of pieces of equipment required. Since most mobile phones do not have RF or LF communication means, it is known to send an identifier of the device in the case of the function of unlocking the vehicle, using for example UWB communication (UWB stands for Ultra Wideband), with which most existing phones are equipped.

[0007] The access device is brought into proximity with the detection device (less than 10 cm away) and recognizes the identifier received by the computer, plus detects the presence of the user's hand, allowing the door to be locked or unlocked.

[0008] In order to detect the presence of a user's hand and allow unlocking of the hatch of the vehicle, such a detection device usually comprises a capacitive sensor in a known manner. Usually, the capacitive sensor is dedicated to one detection zone and in the prior art there is one capacitive sensor for the unlocking zone and one capacitive sensor for the locking zone, the two zones being different.

[0009] According to one example of capacitance measurement, such a capacitive sensor includes a first capacitor that is periodically charged from and discharged into a second capacitor. When the first capacitor is discharged into the second capacitor, the charges on the two capacitors eventually reach equilibrium.

[0010] When the hand is placed on or near the handle (e.g. less than 10 mm away), the charge level of the first capacitor rises. This causes a greater discharge from the first capacitor to the second capacitor and thus a higher balance level with the hand on the handle than without. Such a sensor can therefore be used to detect the user's intention to unlock the vehicle hatch.

[0011] However, using capacitive sensors has a number of disadvantages:

[0012] The detection of user proximity by capacitive sensors is not robust and can produce false detections.

[0013] In particular, under certain environmental conditions, when the ambient air is humid, or when salt is present on the road and sprayed onto the metal body of the vehicle, capacitive coupling may occur between the detection area and the metal parts of the vehicle, thereby preventing any detection of the user's presence by the capacitive sensor.

[0014] Additionally, raindrops or snowflakes on a door handle can increase the capacitance value measured by a capacitive sensor, causing a false positive.

[0015] Finally, capacitive sensor detection is not compatible with handles that are painted metallic or have chrome surfaces; the presence of metal in the handle will couple with the detection area and inhibit detection of the user's presence.

[0016] Some vehicles do not want false detections, while others cannot tolerate them.

[0017] This is the case with vehicles equipped with deployable handles, i.e., handles where the movement of a motorized handle is controlled by detecting the presence of a user, which is fully integrated into the door when at rest and deploys and extends out of the door when activated. With this type of handle, untimely deployment or retraction of the handle due to false detection by the capacitive sensor can put the user's hand at risk of being struck or pinched.

[0018] This is also the case with vehicles equipped with automatic opening systems, where detection of an unlock will not only result in the doors being unlocked, but also in the doors being opened. In this case, false detection can result in untimely opening of the doors.

[0019] Finally, vehicles equipped with a "safety lock" safety feature cannot tolerate false detections, where detection of a lock would result in the vehicle being locked not only from the outside, but also from the inside (anti-theft device). In this case, a false detection could result in the user being locked inside the vehicle.

[0020] In order to overcome these drawbacks, it is known in the prior art to replace at least one of the capacitive sensors (e.g. a capacitive sensor dedicated to locking the vehicle) with a press detection sensor, for example an inductive sensor comprising a metal target that moves towards the coil of the sensor when the user presses the locking or unlocking zone. The change in the inductance of the coil caused by the proximity of the target to the coil of the inductive sensor allows verification of the detection of the user's intention to lock or unlock the vehicle.

[0021] However, integrating a UWB communication device and an inductive press detection sensor into the same vehicle door handle has a big disadvantage: the space inside the handle is becoming increasingly limited (for reasons related to the handle aesthetics), and mechanical integration of the components is no longer always possible due to lack of space and is costly.

[0022] The present invention provides a method and a device for activating a vehicle function, in this case for unlocking and / or locking the vehicle doors, allowing to overcome the disadvantages of the prior art. More particularly, the present invention provides a UWB communication device which has been improved and modified to also allow to detect a user's press on a dedicated surface, thus saving space and reducing costs relative to the prior art. [Summary of the invention]

[0023] The present invention relates to a method for activating a vehicle function from a "hands-free" access device carried by a user by means of an activation device, the activation of which is triggered by detecting a user's press on a contact surface of the vehicle and according to an authentication result of the device, the activation device comprising at least one transceiver located below the contact surface and capable of communicating with the device via ultra-wideband, notably comprising the following steps:

[0024] a. perform ultra-wideband transmission to the equipment,

[0025] b. Receive reflected waves,

[0026] c. Perform the following comparisons during a predetermined period of time,

[0027] i. comparison of the value of the phase of the reflected wave with a predetermined distribution of phase values, said distribution exhibiting a phase rotation, and

[0028] ii. comparison of the value of the amplitude of the reflected wave with a predetermined distribution of amplitude values, said distribution showing an increase in amplitude,

[0029] d. Based on the result of the comparison, detecting a user pressing on the contact surface,

[0030] e. Activate vehicle functions if a press is detected.

[0031] Preferably, the phase rotation corresponds to a change in phase value between -180° and -270° during the predetermined length of time.

[0032] Furthermore, an increase in amplitude preferably corresponds to a change in amplitude value above a threshold value during a predetermined length of time.

[0033] The present invention relates to any device for activating a vehicle function, the device being configured to be installed in a motor vehicle, the activation of the function being triggered by detecting a user pressing on a contact surface of the vehicle and according to an authentication result of the equipment, the activation device comprising at least one transceiver located below the contact surface and capable of communicating with the equipment via ultra-wideband, it is noteworthy that the device comprises:

[0034] a. means for receiving reflected ultra-wideband waves,

[0035] b. means for comparing the value of the phase of the reflected wave during a predetermined length of time with a predetermined phase distribution, said distribution exhibiting a phase rotation,

[0036] c. means for comparing the value of the amplitude of the reflected wave with a predetermined distribution of amplitude values ​​during a predetermined length of time, said distribution showing an increase in amplitude,

[0037] d. means for detecting a user pressing on the contact surface based on the result of said comparison,

[0038] e. Means for activating a vehicle function if a press is detected.

[0039] Preferably, the means for comparing the value of the phase of the reflected wave compares said value with a phase rotation of between -180° and -270° during a predetermined length of time.

[0040] Furthermore, the means for comparing the value of the amplitude preferably compares said value to an increase in the amplitude above a threshold value during a predetermined length of time.

[0041] The invention also relates to any computer program product comprising program code instructions for performing the steps of the method according to any of the above listed features, when said program is executed on a computer.

[0042] Finally, the invention relates to any motor vehicle comprising an activation device according to the features listed above. [Drawings]

[0043] Other features and advantages of the present invention will become more clearly apparent when reading the following description. This is purely illustrative and should be read with reference to the accompanying drawings, in which:

[0044] [ Figure 1 ]: Figure 1 A vehicle equipped with an activation device according to the invention is schematically shown,

[0045] [ Figure 2 ]: Figure 2 A door handle including an ultra-wideband antenna according to the present invention is shown,

[0046] [ Figure 3 ]: Figure 3 An activation device according to the invention is shown,

[0047] [ Figure 4 ]: Figure 4 Contains two figures, the first figure is located at Figure 4 The top graph shows the amplitude as a function of time during the UWB wave transmission, and the second graph is located at Figure 4 The bottom of the figure shows the channel impulse response as a function of time during reception of the reflected UWB wave.

[0048] [ Figure 5 ]: Figure 5 schematically shows a user's finger approaching, touching and then pressing a contact surface, and a graph of the phase and quadrature phase of the reflected wave in each of these three cases,

[0049] [ Figure 6 ]: Figure 6 is a graph showing changes in the phase and quadrature phase of a reflected wave during a predetermined time length, and changes in the phase and amplitude corresponding to the pressing of a user's finger on a contact surface,

[0050] [ Figure 7 ]: Figure 7 is a flow chart showing the steps of the activation method according to the present invention. [Specific implementation method]

[0051] Figure 1A motor vehicle V is shown equipped with a device D for activating a vehicle function according to the invention. The activation device D comprises at least one UWB transceiver EM1 (UWB stands for Ultra Wideband) capable of communicating via ultra-wideband with a portable access device SD (e.g. a smartphone or an electronic key carried by a user U).

[0052] The activation device D further comprises a central control unit 10 electrically connected to the transceiver EM1 .

[0053] The central control unit 10 makes it possible to manage the transmission and reception of UWB data by means of the transceiver. This is known in the art and will not be described in greater detail here.

[0054] Ultra-wideband (UWB) communication means radio frequency communication based on the transmission of pulses with very short duration (generally less than one nanosecond). The bandwidth can therefore reach values ​​of 250 MHz to 500 MHz or even higher. It should be noted that the present invention is also applicable to any other communication means allowing to obtain broadband signals, such as Wi-Fi, which uses OFDM modulation (OFDM stands for Orthogonal Frequency Division Multiplexing), i.e. a method for encoding digital signals by distributing them between orthogonal frequencies in the form of a plurality of subcarriers.

[0055] According to the invention, the transceiver EM1 is located in a body element accessible to the user by touch. Preferably, the transceiver EM1 is located in a door handle (whether it is deployable or not), in a pillar of the driver's door, in a rearview mirror, etc., or in other words, in a body element that can be easily touched by the user. The transceiver EM1 can also be included in an insert located in the window of the driver's door. This location is advantageous because the transceiver EM1 is thus able to transmit to the inside of the vehicle or to the outside of the vehicle, the window attenuating the waves only very slightly when they pass through the window.

[0056] exist Figure 2 In the example shown, the transceiver EM1 is located in the handle P of the door 20 of the motor vehicle V. The transceiver EM1 comprises, in a manner known per se, a UWB antenna AT1 located below a contact surface S. The contact surface S is preferably, but not restrictively, oriented towards the outside of the vehicle V. Activation of a vehicle function is triggered by a press of the user U on this contact surface S, as described below. The contact surface S can be elastically deformable; however, the invention is also applicable to rigid contact surfaces (for example contact surfaces made of rigid plastic).

[0057] According to the invention, the activation of a vehicle function (here the unlocking of the hatch) is based on pre-authentication of the access equipment via ultra-wideband or Bluetooth (this method is known to a person skilled in the art and is not described in detail here), and according to the invention, based on the pressing of a part of the user's body on a contact surface, below which an ultra-wideband antenna is located, as will be described in detail below.

[0058] According to the present invention, the activation device D further comprises (refer to Figure 3 ):

[0059] a. means M1 for receiving reflected ultra-wideband waves,

[0060] b. means M2 for comparing the value of the phase φ of the reflected wave during a predetermined time length ΔT with a predetermined phase distribution, said distribution exhibiting a phase rotation within a range of angular values,

[0061] c. means M3 for comparing the value of the amplitude A of the reflected wave during a predetermined time length ΔT with a predetermined distribution of amplitude values, said distribution exhibiting increases in amplitude above a predetermined threshold value,

[0062] d. means M4 for detecting a pressing of a part of a user's body (eg a finger) on the contact surface S according to the result of said comparison,

[0063] e. Means M5 for activating a vehicle function if a press is detected.

[0064] The receiving means M1, the means for comparing phase values ​​M2, the means for comparing amplitude values ​​M3, the detection means M4 and the activation means M5 are preferably included in the central control unit 10 (refer to Figure 3 ) in the form of software in an integrated circuit.

[0065] According to the embodiment described below, the central control unit 10 further includes a processor 100 and a memory 101 (refer to Figure 3 ), in which instructions are stored that allow the processor to be configured to perform certain specific processing operations, and in particular to implement the steps of the activation method.

[0066] The means M1 for receiving reflected ultra-wideband waves comprise software processing means allowing analysis of the channel impulse response (CIR) of the reflected waves.

[0067] This is Figure 4 It was demonstrated in Figure 4 At the top of FIG. 1 , the amplitude A of the UWB wave emitted by the activation device D at time t=t0 and directed toward the outside of the vehicle V has been shown as a function of the time t.

[0068] exist Figure 4 At the bottom of FIG. , the channel impulse response (CIR) of a wave reflected by the whole body or a part of the body of the user U carrying the access equipment SD and received by the activation device D at time t=t1 is shown.

[0069] It is known in the art to use the time difference Δt between the time t0 of transmitting the wave and the time t1 of receiving the reflected wave and the speed of light to estimate the distance separating the user U carrying the access equipment SD from the activation device D (or vehicle V).

[0070] The received reflected wave signal is a complex signal having an amplitude A and a phase φ.

[0071] It is important to note that the reflected wave is received at the same time as the wave is emitted. There is no pause between the emission of the wave and its reception: emission and reception occur in parallel, with a very slight offset corresponding to the round trip path of the wave and the distance of the access device SD.

[0072] According to the invention, the phase φ and amplitude A of the received reflected wave signal are therefore stored for a predetermined time length ΔT, for example equal to a minimum duration of 4 seconds, ie the time allocated for the wave to make a round trip when, for example, the user touches the contact surface S.

[0073] The comparison means M2 then compares the value of the phase φ with a predetermined phase value distribution within a predetermined time length ΔT.

[0074] The comparison is based on taking samples of the digitized reflected signal over time, which takes the form of a composite I / Q signal (I stands for in-phase and Q stands for quadrature phase). The shape of the reflected signal will depend, among other things, on the shape and distance of the object reflecting the wave (here the user's body) and its radar cross section (RCS). This method is known to those skilled in the art.

[0075] This is Figure 6 , which shows the Q value and I value of the reflected wave signal received during a predetermined time length ΔT when the user approaches and then effectively presses on the contact surface S. The first received reflected wave signal P1 has a phase φ1 and an amplitude A1. At the end of the predetermined time length, the last received reflected wave signal P2 has a phase φ2 and an amplitude A2.

[0076] During this approach-then-press, the phase changes from φ1 = +45° to φ2 = -135°, and thus rotates clockwise by a value of Δφ = -180°.

[0077] Therefore, the predetermined phase value distribution exhibits a rotation between -180° and -270°, which rotation can be adjusted according to the mechanism and performance of the transceiver EM1. This will be explained below.

[0078] The means M3 for comparing the value of the amplitude A compares the value of the amplitude A of the received reflected wave signal with a predetermined amplitude distribution.

[0079] exist Figure 6 In the example, the change in amplitude from the value A1 of the first signal to the value A2 of the last signal is positive. In other words, the approach of the user and then an effective press on the contact surface S results in an increase in the amplitude value by ΔA=A2-A1 within a predetermined time length ΔT.

[0080] The predetermined amplitude value distribution corresponding to a press after approaching consists of an increase in amplitude values ​​(at least ΔAs, for example equal to at least 50% of the initial amplitude value A1). Of course, this increase threshold ΔAs will be calibrated in advance. Here, in this example, the increase threshold is equal to 1.5*A1. This example is completely non-limiting. The threshold can also be calibrated based on the maximum amplitude measured when the user touches the contact surface, the threshold then representing a minimum percentage of this maximum amplitude.

[0081] The means M4 for detecting a press make it possible to verify a press by a user on the contact surface S if, during a predetermined length of time ΔT:

[0082] a. means M2 for comparing phase values ​​to determine that the phase rotation is within the above values, and

[0083] b. Means M3 for comparing the values ​​of the amplitude A determine that the amplitude has increased beyond the above-mentioned threshold value ΔAs (ie for example at least 50%).

[0084] The means M5 for activating a vehicle function then triggers the desired vehicle function V, in this case unlocking a hatch of the vehicle V, if a valid press is detected.

[0085] We will now describe Figure 7 Shown is the method for activating a vehicle function.

[0086] In a preliminary step E0, ultra-wideband communication is established between the access equipment SD and the activation device D. UWB waves are emitted by the activation device D and at the same time the waves reflected by any part of the body of the user U carrying the access equipment SD, in particular her or his fingers, are received by said device D when her or his fingers approach, touch or press the contact surface S.

[0087] In the next step E1 , the reflected waves thus received are processed using the channel impulse response (CIR), thereby allowing the amplitude A and the phase φ of each received wave to be determined.

[0088] Next, in a second step E2 , the phase I and the quadrature phase Q are determined for each received reflected wave signal during a predetermined time length ΔT at least equal to 4 seconds.

[0089] In a third step E3, the phase variation Δφ of the reflected wave is compared with a predetermined phase value distribution during a predetermined time length ΔT. The predetermined distribution has a phase rotation between -270° and -180°.

[0090] If the phase values ​​stored during said time length exhibit a phase rotation between -270° and -180°, the method proceeds to the next step E4, otherwise the method returns to the step of analyzing the received waves and performs a new CIR analysis on the newly received reflected waves.

[0091] If the phase of the received wave has undergone a rotation of its value, in a fourth step E4 , a comparison is made between the value of the amplitude A of the received reflected wave signal and a predetermined amplitude value distribution.

[0092] If the amplitude values ​​stored during the predetermined time length ΔT show an increase ΔA that is greater than a threshold ΔAs, a press by the user U is detected and a vehicle function can be triggered.

[0093] Otherwise, if the amplitude value stored during the predetermined time length ΔT shows no increase or if the increase is less than the threshold ΔAs, no press is detected and the vehicle function is not triggered.

[0094] This is Figure 5 It was displayed in. Figure 5 The changes in phase and amplitude of the received wave during a predetermined time length ΔT are shown for three cases of the user U approaching, touching and then effectively pressing on the contact surface S, below which the UWB communication antenna AT1 is located.

[0095] exist Figure 5 On the left side of , the user's finger is at a distance P1 from the contact surface. At this distance P1, the received wave has an amplitude A1 and a phase φ1.

[0096] exist Figure 5 In the middle, the user's finger is touching the contact surface S: at this new distance P2, the received wave has an amplitude A2 greater than A1 and a phase φ2 offset by -135° relative to φ1.

[0097] exist Figure 5 to the right, the user's finger is pressing the contact surface S: at this new distance P3, the received wave has an amplitude A3 greater than A1, the amplitude variation between A3 and A1 is greater than the threshold ΔAs, and has a phase φ3 offset by -135° relative to φ2 and therefore -270° relative to φ1.

[0098] Since the amplitude change between A1 and A3 is greater than the threshold ΔAs and the phase change between φ1 and φ3 is indeed between -270° and -180°, the pressing of the user U on the contact surface S is verified and the vehicle function is triggered.

[0099] This very particular spiral signature from P1 to P3 represents the approach and then effective pressing of the user U on the contact surface S.

[0100] The method according to the invention for activating a vehicle function is particularly elegant because the ultra-wideband communication antennas which are usually used for communication with “hands-free” access equipment are used here to detect human body contact on a contact surface.

[0101] The UWB antenna thus has two functions, namely its main UWB communication function and an additional press detection function, which makes it possible to dispense with the inductive sensor.

[0102] The synergy of both functions in a single UWB antenna makes it possible to reduce costs and also reduce the space allocated to the active device D.

Claims

1. A method for activating a vehicle function from a "hands-free" access device (SD) carried by a user (U), the activation of the function being triggered by detecting a press of the user on a contact surface (S) of the vehicle and according to an authentication result of the device (SD), by means of an activation device (D), the activation device comprising at least one transceiver (EM1) located below the contact surface (S) and capable of communicating with the device (SD) via ultra-wideband (UWB), the method being characterized in that it comprises the following steps: a) performing ultra-wideband transmission to the equipment, b) receiving the reflected wave, c) performing the following comparisons during a predetermined length of time (ΔT), i) comparison of the phase (φ) values ​​of these reflected waves with a predetermined phase value distribution, The distribution exhibits a phase rotation, and ii) comparison of the amplitude (A) values ​​of these reflected waves with a predetermined amplitude value distribution, The distribution exhibits an increase in amplitude, Represents a spiral signature, d) detecting a press of the user on the contact surface (S) based on the result of said comparison, e) activating the vehicle function if the press is detected.

2. Activation method according to the preceding claim, characterized in that The phase rotation corresponds to a change in the phase value during the predetermined time length (ΔT) between -180° and -270°.

3. The activation method according to any one of the preceding claims, characterized in that An increase in amplitude corresponds to a change in amplitude value above a threshold value (ΔAs) during the predetermined length of time (ΔT).

4. A device (D) for activating a vehicle function, the device being configured to be installed in a motor vehicle (V), the activation of the function being triggered by detecting a press of the user (U) on a contact surface (S) of the vehicle and depending on the result of the authentication of the equipment (SD), the activation device comprising at least one transceiver (EM1) located below the contact surface (S) and capable of communicating with the equipment (SD) via ultra-wideband (UWB), the device (D) being characterized in that it comprises: a) means (M1) for receiving reflected ultra-wideband waves, b) means (M2) for comparing the values ​​of the phase (φ) of these reflected waves during a predetermined length of time (ΔT) with a predetermined phase distribution, said distribution exhibiting a phase rotation, c) means (M3) for comparing the values ​​of the amplitude (A) of the reflected waves during the predetermined length of time (ΔT) with a predetermined distribution of amplitude values, said distribution exhibiting an increase in amplitude, d) means (M4) for detecting a press of the user on the contact surface (S) based on the result of said comparison, e) means (M5) for activating the vehicle function if the pressing is detected.

5. Activation device (D) according to the preceding claim, characterized in that The means (M2) for comparing the values ​​of the phases of the reflected waves compare said values ​​with a phase rotation during the predetermined length of time (ΔT) between -180° and -270°.

6. An activation device (D) as claimed in any one of claims 4 and 5, characterized in that The means (M3) for comparing the value of the amplitude (A) compare said value with an increase in the amplitude above a threshold value (ΔAs) during the predetermined length of time (ΔT).

7. A computer program product comprising program code instructions for executing the steps of the method according to any one of claims 1 to 3 when the program is executed on a computer.

8. A motor vehicle (V), characterized in that The motor vehicle comprises an activation device (D) as claimed in claims 4 to 6.

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