METHOD FOR ACTIVATING A VEHICLE FUNCTION AND ASSOCIATED ACTIVATION DEVICE

Abstract

The invention relates to a method for activating a vehicle function by an activation device (D), comprising at least two transceivers (Tx1, Tx2) communicating with a user's portable equipment (SD), and with each other in ultra wide band, the invention comprising the steps: Emission by a first transceiver, Calculation of a radius of a circle centered around the first transmitter as a function of the time of flight of the waves reflected by the portable equipment, and determination of a perimeter of said circle, Comparison of a wave profile received from the second transceiver, with a predetermined received wave profile Detection of a presence as a function of the result of the comparison, If a presence is detected, calculation of a distance (d2) between the second transceiver and said presence, Location of the portable equipment by calculation of an intersection (I) between said distance (d2) and the perimeter (C),Activation of the vehicle function based on said location. Figure for the abstract: Fig. 1,

Description

Title of the invention: METHOD FOR ACTIVATING A VEHICLE FUNCTION AND ASSOCIATED ACTIVATION DEVICE Technical field

[0001] The invention relates to a method for activating a function of a motor vehicle and an associated activation device. The invention applies particularly but in no way limitingly to the hands-free access function of a motor vehicle, that is to say to the function of locking and unlocking the openings of a motor vehicle. Prior art

[0002] In a motor vehicle, it is known to use vehicle function activation devices capable of detecting the presence of a hand or a foot of a user of the vehicle and thus allowing the locking or unlocking of all or part of the openings of the vehicle, for example the doors or the trunk. For example, the detection of the presence of a user's hand on or in front of a door handle coupled with the recognition of an identifier of a "hands-free" access device worn by this user, allows the locking and unlocking of these openings.

[0003] A so-called "hands-free" access system for a motor vehicle allows an authorized user to lock and / or unlock the openings of his vehicle without having to physically press buttons on a key. To do this, the vehicle identifies portable equipment such as a badge or a remote control carried or even a key, by the user and if the badge or the remote control or the key is located in a predetermined area around the vehicle or in the vehicle and is identified as belonging to the vehicle, then the vehicle automatically locks / unlocks its openings according to the user's intention, without the user having to physically handle a key.

[0004] To do this, when the user approaches the vehicle, communication is established on a wireless communication link between the “hands-free” access equipment, for example an electronic badge or a smart mobile phone, and the vehicle function activation device in order to authenticate said access equipment using its identifier.

[0005] For this purpose, the activation device comprises at least one radiofrequency antenna allowing the reception of the identifier sent by the “hands-free” access equipment. The activation device is connected to an electronic computer of the vehicle (“ECU”: English abbreviation for “Electronic Control Unit”) to which it transmits the identifier.

[0006] According to the state of the art, the access equipment is generally an electronic badge. The signal received by the antenna of the activation device, comprising the identifier of the access equipment, is transmitted via RF (Radiofrequency) or LF (Low Frequency) waves. The precise location of the portable equipment around the vehicle is carried out by measuring the intensity of the LF signal received by the portable equipment (via the antennas and the electronic control unit) from the vehicle, more commonly called RSSI measurements (Received Signal Strength Indication, or measurement of the power received by a signal received by an antenna).The measurement of the power of each signal received by the portable equipment from each antenna of the plurality of LF antennas located on the vehicle V is received and analyzed by an activation device, on board the vehicle, which thus determines by triangularization, the position of the portable equipment relative to said LF antennas, that is to say relative to the vehicle.

[0007] Depending on the location of the portable equipment identified by the vehicle, in said location zones certain actions specific to said location zones are automatically carried out, unlocking / locking or prior switching on of the passenger compartment lighting (also called “welcome lighting” in English).

[0008] Nowadays, however, it is increasingly common to use a mobile phone to perform authentication functions, which makes it possible to avoid using a dedicated electronic badge and thus limit the number of devices. Most mobile phones do not have RF or LF communication means. It therefore becomes necessary to adapt the "hands-free" access and / or starting system to a vehicle so that it can also operate with a mobile phone equipped with other communication standards, such as, for example, "Ultra Wide Band" in English or Ultra Large Band, ULB in French, or by BLE ("Blue Tooth Low Energy" ®), or by WIFI communication ("wireless fidelity" in English or wireless fidelity) and no longer only via radio waves and low frequencies (RF, LF).Ultra wideband (UWB) is a radio modulation technique based on the transmission of very short pulses, often less than a nanosecond. Thus, the bandwidth can reach very high values.

[0009] The approach of the access equipment close to the activation device (less than 2m) and the recognition of the identifier received by the computer, coupled with the detection of the presence of the user's hand, allows the door to be locked or unlocked.

[0010] The disadvantage of using ULB communication means lies in the location accuracy of the access equipment (mobile telephone or badge) which is degraded compared to the use of low frequency communication means of the prior art at 125 kHz.

[0011] Ultra Wide Band is in fact more sensitive to reflections and interference. Thus, for precise location, the vehicle must be equipped with six to eight ULB transmitters / receivers (four to six outside the vehicle and two inside the vehicle), so that three ULB transmitters / receivers are always visible to the access equipment, whereas in low frequency, according to the prior art, a single visible transceiver can precisely locate the access equipment. This increase in the number of ULB transmitters / receivers on the vehicle results in an additional cost for the activation device, which is not desirable.

[0012] The number of UWB transmitters / receivers on the vehicle cannot be reduced to three or four without running the risk that the activation device is often located in shadow areas, in particular when the user approaches the vehicle to unlock his vehicle and the device is only visible to a single transmitter / receiver. In this case, unlocking cannot be triggered.

[0013] The disadvantage for the user is major since certain functions will not be activated, for example the automatic “hands-free” unlocking or the automatic “hands-free” locking of the vehicle, when the user enters the unlocking or unlocking zone.

[0014] The invention therefore proposes a method for activating a vehicle function as well as an associated activation device overcoming the drawbacks of the prior art, more particularly allowing reliable and precise location of the access equipment. Presentation of the invention

[0015] The invention relates to a method for activating a vehicle function by an activation device intended to be mounted on a vehicle, comprising at least two ultra-wideband transmitters and receivers located on either side of an opening, and on the same side of the vehicle, separated by a predetermined distance and capable of communicating with a user's portable equipment, the method being remarkable in that the two transmitters and receivers are adapted so that they can communicate with each other in ultra-wideband, and in that it comprises the following steps: a. Emission of ultra-frequency waves by at least one first transmitter-receiver, b. Reception of reflected waves from the portable equipment and determination of a time of flight of the waves, c. Calculation of a radius of a circle centered around the first transmitter receiver as a function of the flight time, and determination of a perimeter of said circle on which the portable equipment may be located, d. Reception of reflected waves from the second transmitter-receiver, e. Comparison of a profile of the waves received over time with a predetermined profile of received waves, f. Detection of a presence in a predetermined area around the two transmitters and receivers based on the result of the comparison, g. If a presence is detected, calculation of a distance between the second transmitter receiver and said presence, h. Location of the portable equipment based on the calculation of an intersection between said calculated distance and the previously determined perimeter, i. Activation of the vehicle function based on said location.

[0016] Preferably; the received wave profile corresponds to an impulse response per channel and in that a presence is detected by the presence of two consecutive peaks in said response

[0017] The invention also relates to a device for activating a vehicle function intended to be embedded in a vehicle, comprising at least two ultra-wideband transmitters and receivers located on either side of an opening, separated by a predetermined distance, and located on the same side of the vehicle, capable of communicating with a user's portable equipment, the device being remarkable in that the two transmitters and receivers are capable of communicating with each other and in that it further comprises: a. Means for determining a time of flight of reflected waves from the portable equipment, b. Means for calculating a radius of a circle centered around the first transmitter-receiver as a function of the time of flight, and for determining a perimeter of said circle on which the portable equipment may be located, c. Means for comparing a reflected wave profile from a second transmitter with a predetermined wave profile, d. Means for detecting a presence in a predetermined area around the two transmitters and receivers depending on the result of the comparison, e. Means for calculating a distance between the second transmitter receiver and said presence, f. Means for locating the portable equipment based on the calculation of an intersection between said calculated distance and the previously determined perimeter, g. Means for activating the vehicle function based on said location.

[0018] Advantageously, the received wave profile corresponds to an impulse response per channel and in that the means for detecting a presence are capable of detecting two consecutive peaks in said response.

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

[0020] Finally, the invention relates to any motor vehicle comprising an activation device according to any one of the characteristics listed above. Brief description of the drawings

[0021] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This is purely illustrative and must be read in conjunction with the appended drawings in which:

[0022] [Fig.l]: [Fig.l] schematically represents a motor vehicle equipped with the activation device according to the invention,

[0023] [Fig.2]: [Fig.2] illustrates the intersection point I according to the activation method of the invention,

[0024] [Fig.3]: [Fig.3] schematically represents the activation device according to the invention,

[0025] [Fig.4]: [Fig.4] is a flowchart representing the different stages of the process activation according to the invention

[0026] [Fig.5]: [Fig.5] is a graph representing the impulse response per channel depending on the time in the case where a presence is located between the two transmitters. Description of the embodiments

[0027] In [Fig.l] a motor vehicle V is shown comprising an activation device D for a vehicle function according to the invention. The activation device D according to the invention makes it possible to: a. detect the presence of a user U in a predetermined area around the vehicle V, b. to authenticate the SD portable access device carried by the user, in order to activate a vehicle function.

[0028] By vehicle function is meant the locking / locking of the openings of the vehicle V, such as the driver's door, or the rear trunk of the vehicle V but also the switching on of the heated seats, the switching on of the ceiling light ("welcome lighting" in English or welcome light), or even the presetting of the seats or a radio station and this even before the user U has entered the vehicle.

[0029] In [Fig.l], a motor vehicle V is shown equipped with an activation device D for a vehicle function according to the invention. The activation device D comprises at least two transmitters and receivers Txl, Tx2, Tx3, Tx4 in Ultra Wide Band ULB capable of communicating in ultra wide band with portable access equipment SD, for example a smartphone or an electronic key carried by a user U.

[0030] The activation device D further comprises a central control unit 10 electronically connected to the transmitters and receivers Txl, Tx2, Tx3, Tx4.

[0031] This central control unit 10 makes it possible to manage the transmission and reception of data in ULB via the transceivers. This is known from the prior art and will not be detailed further here.

[0032] Ultra Wide Band ULB communication is understood to mean radiofrequency communication which is based on the transmission of pulses of very short duration, often less than a nanosecond. Thus, the bandwidth can reach very high values ​​between 250 and 500 MHz and beyond. Note that the invention also applies to any other means of communication allowing a wideband signal to be obtained, for example Wifi which uses OFDM (“Orthogonal Frequency Division Multiplex” type modulation), i.e. a method of coding digital signals by orthogonal frequency distribution in the form of multiple subcarriers.

[0033] According to the invention, the transmitters and receivers Txl, Tx2, Tx3, Tx4 are located in an element of the bodywork oriented towards the outside of the vehicle V in order to transmit towards the outside of the vehicle V on the side where the user approaches the vehicle V. According to the invention, at least two transmitters and receivers Txl, Tx2 are located on the same side of the vehicle, and on either side of an opening, here a door PI that the user wishes to unlock, that is to say near an element of the bodywork towards which the user wishes to approach.

[0034] In the example illustrated in [Fig.l], the two transceivers Txl, Tx2 are located on either side of a door PI, located on the driver's side of the motor vehicle V. The transceivers Txl, Tx2 each comprise, in a manner known per se, an ultra-wideband ULB antenna and ultra-wideband transmission and reception means not detailed and not shown here, known from the state of the art.

[0035] As explained previously, it may happen that the user U approaching the vehicle is not “seen” by all the transmitters Txl, Tx2, Tx3, Tx4 located on the vehicle.

[0036] In this case, as illustrated in [Fig.l], when user U arrives from the front of the vehicle V, it is only seen by a first transmitter receiver Txl, located closest to it, because it is in its transmission zone Zl. On the other hand, it is not seen by the second transmitter receiver Tx2, located on the other side of the door PI, because it is not in its transmission zone Z2.

[0037] As for the two other transceivers Tx3, Tx4 located on the other side of the vehicle V, either they are too far away to communicate with the portable equipment SD carried by the user U, or the various reflections and obstacles that the waves emitted or received by these two transceivers Tx3, Tx4 undergo between said transceivers Tx3, Tx4 and the portable equipment SD mean that locating the portable equipment from these two transceivers is neither reliable nor robust.

[0038] The invention therefore proposes an activation device making it possible to overcome the drawbacks of the prior art.

[0039] For this purpose, according to the invention the two transmitters Txl, Tx2 which are located on the same side of the vehicle and on either side of an opening are able to communicate with each other in ultra wide band.

[0040] Furthermore, still according to the invention, the activation device D comprises: a. Means for determining M1 a time of flight of reflected waves coming from the portable equipment SD, emitted by the first transmitter receiver Txl b. Means for calculating a radius M2 of a circle centered around the first transmitter receiver as a function of the flight time, and determining a perimeter of said circle on which the portable equipment can be located, c. Means M3 for comparing a reflected wave profile from a second transmitter with a predetermined wave profile, d. Means M4 for detecting a presence in a predetermined area around the two receiver transmitters depending on the result of the comparison, e. Means for calculating a distance M5 between the second transmitter receiver and said presence, f. Means of locating M6 the portable equipment based on the calculation of an intersection between said calculated distance and the previously determined perimeter, g. Means of activation M7 of the vehicle function according to said location.

[0041] The means M1 for determining a flight time are capable of calculating the round-trip travel time or also called flight time TOF (“Time of flight” in English) of the waves between the first transmitter-receiver Txl and the portable equipment SD. This is known to those skilled in the art. The flight time thus calculated makes it possible to determine a distance separating the first Txl transmitter receiver from the portable SD equipment.

[0042] From this distance, the calculation means M2 determine the perimeter of a circle centered around the first transmitter receiver Txl, the radius R of which is equal to the distance previously calculated from the time of flight TOF. The portable equipment SD can be located at any point on said perimeter C.

[0043] The comparison means M3 then compare a profile of the waves received from the second transceiver Tx2, emitted by the first transceiver Txl with a predetermined profile of received waves. The profile of the waves received here is the CIR or “Channel Impulse Response” in English, impulse response per channel. The comparison means M3 comprise means for determining the parameter called CIR (“Channel Impulse Response” in English or impulse response), that is to say means for measuring the received waves sampled according to the time t. It should be noted that either the amplitude of the CIR or the phase of the CIR can be used. In this example the frequency measurements of the received waves are transformed by the inverse of a Fourier Transform in order to generate values ​​in time units.The amplitude of the CIR consists of the absolute value of the real part and the imaginary part of the values ​​in time units. The phase of the CIR consists of the arctangent of the ratio of the imaginary part divided by the part of the values ​​in time units. The calculation of the amplitude or the phase of the CIR are well known to those skilled in the art and will not be detailed further here. The profile of the CIR over time makes it possible to detect any object or presence likely to reflect the emitted waves. Thus, a peak on the CIR profile corresponds either to waves received directly, in line of sight, without obstacles, or to waves received but which have been reflected by an obstacle present on their path.

[0044] According to the invention, the predetermined received wave profile comprises a single peak, that which corresponds to the presence of the second transmitter receiver Tx2, which reflects the waves.

[0045] If a presence is located around the two transmitters / receivers Txl, Tx2, said presence will reflect the waves and thus create a second peak on the profile of the CIR, the detection means M4 then detect a presence in a predetermined zone around the two transmitters / receivers Txl, Tx2. The two transmitters / receivers Txl, Tx2 being separated by a predetermined distance dl (see [Fig.2]), it is thus possible, thanks to the CIR and at the instant of appearance of the first peak and the second peak, to determine a distance D' separating the second transmitter / receiver Tx2 from the presence.

[0046] This is illustrated in [Fig.5] which is a graph representing the power spectral density of the propagation channel or impulse response per channel, i.e. CIR as a function of time t. This type of representation of the CIR is known to man of the profession and will not be detailed further here.

[0047] At the first instant tl, there is a first peak Pki, of reflected waves, which corresponds to the waves reflected by the second transmitter-receiver Tx2. The first instant therefore corresponds to the round-trip flight time of the waves necessary to travel twice the distance dl separating the two transmitter-receivers Txl, Tx2.

[0048] At the second instant t2, there is a second peak Pk2 of reflected waves which corresponds to the waves reflected by a presence located in the vicinity of two transmitters / receivers Txl, Tx2. The calculation means M5 determine a distance d2 between the second transmitter / receiver Tx2 and said presence from the delay At between the first instant tl and the second instant t2.

[0049] Once the perimeter of the circle around the first transceiver Txl on which the portable equipment SD can be located is determined and the distance d2 separating the presence of the second transceiver Tx2 is calculated, the means for locating the portable equipment SD determine a point of intersection I on the circle located at a distance d2 from the second transceiver Tx2.

[0050] This intersection point I is considered according to the invention as the position of the portable equipment SD.

[0051] The activation means M7 trigger the activation of the vehicle function, in this example the unlocking of the driver's door PI, according to the position I of the portable equipment SD.

[0052] The means M1 for determining a wave flight time, the means M2 for calculating a radius M2 of a circle centered around the first transmitter-receiver, the means M3 for comparing a reflected wave profile from a second transmitter with a predetermined wave profile, the means M4 for detecting a presence in a predetermined area around the two transmitter-receivers as a function of the result of the comparison, the means M5 for calculating a distance M5 between the second transmitter-receiver and said presence, the means M6 for locating the portable equipment as a function of the calculation of an intersection between said calculated distance and the previously determined perimeter, and the means M7 for activating the vehicle function as a function of said location are preferably in the form of software integrated into a printed circuit located in the central control unit 10.

[0053] The central control unit 10 also comprises a processor 100 and a memory 101 (see [Fig. 3]) in which instructions are recorded for configuring the processor to execute certain particular processing operations, in particular to implement the steps of the activation method, according to the embodiment as described below.

[0054] The activation process, illustrated in [Fig.4] will now be described. This process illustrates the case where the activation function and unlocking of the driver's door PI of the vehicle V but can be applied to other vehicle functions, or to other openings such as the front right door P2, or the trunk P3 (see [Fig.2]).

[0055] During a first step E0, the first transceiver Txl transmits waves in ultra wide band ULB. These waves are then received and reflected by portable access equipment SD located in the transmission zone of said first transceiver Txl.

[0056] Once the waves have been received by the first transmitter / receiver Txl, a time of flight, TOF of the waves is calculated (step E1).

[0057] Then, from the flight time, a distance separating the first transmitter receiver Txl from the portable equipment is determined. From this distance, a perimeter C (see [Fig.2]) of a circle around said transmitter Txl is defined (step E2) whose radius R is equal to said distance. It is then considered that the portable access equipment SD can be located at any position on this perimeter.

[0058] In the following step E3, the waves emitted by the first transmitter receiver Txl are simultaneously received by the second transmitter receiver Tx2

[0059] A CIR profile of the waves received from the second transceiver Tx2 is then determined and is compared (step E4) to a predetermined received wave profile comprising only a single peak Pki corresponding to the second transceiver Tx2 capable of reflecting the waves.

[0060] If a second peak Pk2 is detected on the CIR profile corresponding to the reflection of a presence located in a predetermined zone around the two transmitters / receivers Txl, Tx2 (step E5), then a distance d2 is calculated (step E6) separating the second transmitter / receiver Tx2 from said presence as a function of a delay At between the two peaks Pki and Pk2.

[0061] Then according to the invention, an intersection point I is determined between the perimeter C of the circle and a segment of length d2 having as its origin the second transmitter receiver Tx2 (step E7). According to the invention, the position of this intersection point I is considered as the position of the access equipment SD.

[0062] Depending on the position of this intersection point I and its belonging to a predetermined zone authorizing the activation of certain vehicle functions, one or more vehicle functions such as unlocking the door PI is activated (step E8).

[0063] The invention therefore ingeniously makes it possible to determine the position of the portable SD equipment, even when it is only visible to a Txl transmitter / receiver, simply by using the reflection of the waves induced by the presence of the user wearing said equipment and its effect on the wave profile received when the two transmitter / receivers communicate with each other.

[0064] The invention is all the more remarkable as it requires only a few means, in the occurrence of software means, easy to implement and inexpensive.

Claims

Claims

1. Method for activating a vehicle function by an activation device (D) intended to be on board a vehicle, comprising at least two ultra-wideband (ULB) transceivers (Txl, Tx2) located on either side of an opening (PI), and on the same side of the vehicle (V), separated by a predetermined distance (dl) and capable of communicating with a portable user equipment (SD), the method being characterized in that the two transceivers (Txl, Tx2) are adapted so that they can communicate with each other in ultra-wideband, and in that it comprises the following steps: a. Emission of waves by at least one first transmitter receiver (Txl), b. Reception of reflected waves from the portable equipment (SD) and determination of a time of flight (TOF) of the waves, c. Calculation of a radius (R) of a circle centered around the first transmitter receiver (Txl) as a function of the time of flight (TOF), and determination of a perimeter (C) of said circle on which the portable equipment can be located, d. Reception of reflected waves from the second transmitter receiver (Tx2), e. Comparison of a profile (CIR) of the reflected waves received according to time (t) with a predetermined profile of received waves, f. Detection of a presence (U) in a predetermined zone (Zl, Z2) around the two transmitters (Txl, TX2) according to the result of the comparison, i. If a presence is detected, calculation of a distance (d2) between the second transmitter receiver (Tx2) and said presence (U), ii. Location of the portable equipment (SD) based on the calculation of an intersection (I) between said calculated distance (d2) and the previously determined perimeter (C), iii. Activation of the vehicle function according to said location.

2. Activation method according to the preceding claim, characterized in that the received wave profile (CIR) corresponds to an impulse response per channel and in that a presence is detected by the presence of two consecutive peaks (Pki, Pk2) in said response

3. Device (D) for activating a vehicle function intended to be embedded in a vehicle, comprising at least two ultra-wideband (ULB) transceivers (Txl, Tx2) located on either side of an opening (PI), separated by a predetermined distance (dl), and located on the same side of the vehicle (V), capable of communicating with portable user equipment (SD), the device (D) being characterized in that the two transceivers (Txl, Tx2) are capable of communicating with each other in ultra-wideband and in that it further comprises: a. Means for determining (Ml) a time of flight (TOF) of reflected waves from the portable equipment (SD), b. Means for calculating (M2) a radius (R) of a circle centered around the first transmitter receiver (Txl) as a function of the flight time, and for determining a perimeter (C) of said circle on which the portable equipment (SD) can be located, c. Comparison means (M3) between a reflected wave profile (CIR) received from a second transmitter with a predetermined received wave profile, d. Means for detecting (M4) a presence in a predetermined zone (Zl, Z2) around the two transmitters / receivers (Txl, Tx2) depending on the result of the comparison, e. Means (M5) for calculating a distance (d2) between the second transmitter receiver (Tx2) and said presence (U), f. Means for locating (M6) the portable equipment (SD) based on the calculation of an intersection (I) between said calculated distance (d2) and the previously determined perimeter (C), g. Means for activating (M7) the vehicle function depending on said location.

4. Activation device (M7) according to the preceding claim, characterized in that the received wave profile corresponds to a response impulse per channel (CIR) and in that the presence detection means (M4) are capable of detecting two consecutive peaks (Pki, Pk2) in said response.

5. A computer program product comprising program code instructions for executing the steps of the method according to any one of claims 1 to 2 when said program is executed on a computer.

6. Motor vehicle (V), characterized in that it comprises an activation device (D) according to any one of claims 3 and 4.

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