Method for activating a vehicle function and associated activation device

Abstract

The invention relates to a method for activating a vehicle function using an activation device (D) comprising at least two transceivers (Tx1, Tx2) communicating with a portable user equipment (SD) and communicating with each other via ultra-wideband communication, the invention comprising the following steps: 0 transmitting using a first transceiver; 0, calculating the radius of a circle centered on the first transceiver from the time of flight of the wave reflected by the portable equipment, and determining the circumference of said circle; 0 comparing the curve of the received reflected wave originating from the second transceiver with a predetermined received wave curve; 0 detecting the presence as a function of the result of the comparison; if a presence is detected, calculating a distance (d2) between the second transceiver and the presence; positioning the portable equipment by calculating an intersection point (I) between the distance (d2) and the circumference (C); the vehicle function is activated as a function of the position.

Description

[Technical field]

[0001] The invention relates to a method for activating a function of a motor vehicle and to an associated activation device. The invention is suitable in particular, but in no way in a restrictive manner, for a function of hands-free access to a motor vehicle, ie for locking and unlocking an opening element of a motor vehicle. [Background Technology]

[0002] In motor vehicles, it is known practice to use vehicle function activation devices that are able 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's opening elements, such as doors or a trunk. 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 opening elements.

[0003] "Hands-free" access systems for accessing motor vehicles allow an authorized user to lock and / or unlock the opening elements of his vehicle without physically pressing a button on the key. For this purpose, the vehicle recognizes a portable device such as a key fob or remote control or even a key carried by the user, and if the key fob or remote control or the key is located in a predetermined area around the vehicle or in the vehicle and is recognized as belonging to the vehicle, the vehicle automatically locks / unlocks its opening elements according to the user's intention, without the user having to physically manipulate the key.

[0004] To this end, when the user approaches the vehicle, communication is established via a wireless communication link between a “hands-free” access device (eg an electronic key fob or a smartphone) and a vehicle function activation device in order to authenticate the access device by means of its identifier.

[0005] To this end, the activation device comprises at least one radio frequency antenna for receiving the identifier sent by the "hands-free" access equipment. The activation device is connected to the vehicle's electronic computer ("ECU": short for "electronic control unit") to which it transmits the identifier.

[0006] According to the prior art, the access equipment is usually an electronic key fob. The signal received by the antenna of the activation device (including the identifier of the access equipment) is transmitted via RF (radio frequency) or LF (low frequency) waves. By measuring the strength of the LF signal originating from the vehicle received by the portable equipment (via the antenna and the electronic control unit), the precise position of the portable equipment around the vehicle can be found, and these strength measurements are more generally referred to as RSSI (received signal strength indication) measurements. The strength measurements of each signal received by the portable equipment from each of the multiple LF antennas located on the vehicle V are received and analyzed by the activation device installed in the vehicle, so that the activation device uses triangulation to determine the position of the portable equipment relative to the LF antenna (i.e., relative to the vehicle).

[0007] Depending on the position of the portable equipment recognized by the vehicle within the localization area, certain actions specific to the localization area are automatically performed: unlocking / locking or preliminary switching on of the lighting in the passenger compartment (also called welcome lighting).

[0008] However, it is increasingly common to use a mobile phone to perform authentication functions, which avoids the need for a dedicated electronic key fob and thus limits the number of devices. Most mobile phones do not have RF or LF communication facilities. Therefore, there is a need to adapt a "hands-free" starting and / or access system for a vehicle so that the system can also communicate with other devices equipped with other communication standards (e.g., Ultra Wideband, or BLE (Bluetooth Low ), or Wi-Fi (Wireless Fidelity) communications) instead of using only radio waves and low-frequency waves (RF and LF). In particular, Ultra-Wideband (UWB) is a radio modulation technology based on the transmission of pulses with very short duration (usually less than a nanosecond). As a result, the passband can reach very large values.

[0009] The access equipment comes into proximity with the activation device (less than 2 m from the activation device) and recognizes the identifier received by the computer, which, combined with the detection of the user's hand, allows locking or unlocking the vehicle doors.

[0010] A disadvantage of using a UWB communication device is that the location accuracy of the access device (mobile phone or key fob) is poorer than using prior art low frequency 125 kHz communication devices.

[0011] This is because UWB is more sensitive to reflections and interference. Therefore, precise positioning involves equipping the vehicle with six to eight UWB transceivers (four to six on the outside of the vehicle and two on the inside), so that three UWB transceivers are always visible to the access equipment, while according to the prior art, at low frequencies, a single visible transceiver can accurately locate the access equipment. The increase in the number of UWB transceivers on the vehicle will result in undesirable additional costs for the activation equipment.

[0012] It is impossible to reduce the number of UWB transceivers on a vehicle to three or four without putting activated devices at risk of being constantly in black spots, especially when a user approaches the vehicle to unlock it and the device is visible to only one transceiver. In this case, unlocking cannot be triggered.

[0013] For the user, the disadvantage is considerable, since certain functions are not activated when the user enters an unlocked area or a locked area, for example, automatic “hands-free” unlocking or automatic “hands-free” locking of the vehicle.

[0014] The present invention therefore proposes a vehicle function activation method and an associated activation device which overcome the disadvantages of the prior art and more particularly allow a reliable and precise positioning of access equipment. [Summary of the invention]

[0015] The invention relates to a method for activating a vehicle function using an activation device intended to be fitted on a vehicle, the activation device comprising at least two ultra-wideband transceivers, the at least two ultra-wideband transceivers being located on both sides of an opening element and on the same side of the vehicle, at a predetermined distance and capable of communicating with a portable user equipment, the method being characterized in that the two transceivers are adapted so that they can communicate with each other via ultra-wideband communication, and wherein the method comprises the following steps:

[0016] a. using at least one first transceiver to transmit UHF waves;

[0017] b. receiving the reflected wave from the portable device and determining the flight time of the wave;

[0018] c. calculating the radius of a circle centered at the first transceiver according to the flight time, and determining the circumference of the circle where the portable equipment may be located;

[0019] d. receiving the reflected wave from the second transceiver;

[0020] e. Comparing the curve of the received wave with the predetermined received wave curve over time;

[0021] f. detecting the presence of an object in a predetermined area around the two transceivers based on the comparison result;

[0022] g. If an object is detected, the distance between the second transceiver and the object is calculated;

[0023] h. locating the portable equipment based on the calculation of the intersection between the calculated distance and the previously determined perimeter;

[0024] i. Activate vehicle functions based on the position.

[0025] Preferably, the curve of the received wave corresponds to the impulse response of each channel and the presence is detected by the presence of two consecutive peaks in said response.

[0026] The invention also relates to a device for activating a vehicle function, the device being intended to be mounted on a vehicle, the device comprising at least two ultra-wideband transceivers, the at least two ultra-wideband transceivers being located on both sides of an opening element, at a predetermined distance from each other and on the same side of the vehicle, capable of communicating with a portable user equipment, the device being characterized in that the two transceivers are capable of communicating with each other, and wherein the device further comprises:

[0027] a. means for determining the time of flight of a reflected wave originating from a portable device;

[0028] b. means for calculating the radius of a circle centered at the first transceiver according to the flight time, and determining the circumference of the circle in which the portable equipment may be located;

[0029] c. means for comparing the curve of the reflected wave originating from the second transmitter with a predetermined received wave curve;

[0030] d. means for detecting the presence of an object in a predetermined area around the two transceivers based on the result of the comparison;

[0031] e. means for calculating the distance between the second transceiver and said object;

[0032] f. means for locating the portable equipment based on the calculation of the intersection between the calculated distance and the previously determined perimeter;

[0033] g. Means for activating a vehicle function dependent upon said position.

[0034] Advantageously, the curve of the received wave corresponds to the impulse response of each channel, and the means for detecting the presence are capable of detecting two consecutive peaks in said response.

[0035] The invention also relates to any computer program product comprising program code instructions for executing the steps of the method according to any of the aforementioned features, when said program is executed on a computer.

[0036] Finally, the invention relates to any motor vehicle comprising an activation device according to any one of the previously mentioned characteristics. [Drawings]

[0037] Further features and advantages of the present invention will become more clearly apparent upon reading the following description. The description is purely illustrative and should be read with reference to the accompanying drawings, in which:

[0038] [ Figure 1 ]: Figure 1 A motor vehicle equipped with an activation device according to the invention is schematically shown;

[0039] [ Figure 2 ]: Figure 2 Intersection I according to the activation method of the present invention is shown;

[0040] [ Figure 3 ]: Figure 3 Schematically illustrates an activation device according to the invention;

[0041] [ Figure 4 ]: Figure 4 is a flow chart showing the various steps of the activation method according to the present invention;

[0042] [ Figure 5 ]: Figure 5 is a graph showing the impulse response of each channel versus time for the case where an object is located between the two transmitters. [Specific implementation method]

[0043] Figure 1 A motor vehicle V is shown comprising an activation device D according to the invention for activating a vehicle function. The activation device D according to the invention allows:

[0044] a. Detecting the presence of a user U in a predetermined area around the vehicle V;

[0045] b. Authenticate the portable access device SD carried by the user,

[0046] in order to activate vehicle functions.

[0047] “Vehicle functions” are understood to mean locking / unlocking opening elements of the vehicle V, such as the driver's door or the trunk at the rear of the vehicle V, but also include turning on the heated seats, turning on the ceiling lighting (“welcome lighting”), or even pre-adjusting the seats or pre-tuning the radio station before the user U enters the vehicle.

[0048] Figure 1 A motor vehicle V is shown equipped with an activation device D for activating vehicle functions according to the invention. The activation device D comprises at least two UWB transceivers Tx1, Tx2, Tx3, Tx4 capable of communicating with a portable access equipment SD (e.g. a smartphone or an electronic key carried by a user U) via ultra-wideband communication.

[0049] The activation device D further comprises a central control unit 10 electrically connected to the transceivers Tx1 , Tx2, Tx3, Tx4.

[0050] The central control unit 10 allows managing the transmission and reception of UWB data by the transceiver. This is known in the prior art and will not be described in further detail herein.

[0051] Ultra-wideband (UWB) communication is understood to mean radio frequency communication based on transmission of pulses of very short duration, generally lasting less than one nanosecond. The bandwidth can therefore reach values ​​between 250 MHz and 500 MHz and even higher. It should be noted that the invention is also applicable to any other communication means allowing broadband signals to be obtained, such as Wi-Fi, which uses modulation of the OFDM (Orthogonal Frequency Division Multiplexing) type, i.e. a method for encoding digital signals by distributing orthogonal frequencies in the form of multiple subcarriers.

[0052] According to the invention, transceivers Tx1, Tx2, Tx3, Tx4 are located in a body element oriented toward the outside of the vehicle V in order to transmit to the outside of the vehicle V on the side on which the user approaches the vehicle V. According to the invention, at least two transceivers Tx1, Tx2 are located on the same side of the vehicle and on both sides of an opening element (in this case, the door P1 that the user wishes to unlock, i.e. close to the body element that the user wishes to approach).

[0053] exist Figure 1 In the example shown, two transceivers Tx1, Tx2 are located on either side of a door P1, on the driver's side of the motor vehicle V. The transceivers Tx1, Tx2 each comprise, in a manner known per se, an ultra-wideband (UWB) antenna, as well as ultra-wideband transmitting and receiving means, which are not described or shown herein, but are known in the prior art.

[0054] As explained before, a user U approaching the vehicle may not be "seen" by all transceivers Tx1 , Tx2, Tx3, Tx4 located on the vehicle.

[0055] In this case, if Figure 1 As shown, when the user U arrives from the front of the vehicle V, the user can only be seen by the first transceiver Tx1 closest to the user because the user is located in the transmission area Z1 of the first transceiver. However, the user cannot be seen by the second transceiver Tx2 located on the other side of the door P1 because the user is not located in the transmission area Z2 of the second transceiver.

[0056] As for the other two transceivers Tx3, Tx4 located on the other side of the vehicle V, either they are too far away to communicate with the portable device SD carried by the user U, or the waves transmitted or received by the transceivers Tx3, Tx4 encounter various reflections and obstacles between the two transceivers Tx3, Tx4 and the portable device SD, which means that positioning the portable device based on these two transceivers is neither reliable nor robust.

[0057] Therefore, the present invention proposes an activation device capable of overcoming the disadvantages of the prior art.

[0058] To this end, according to the invention, two transceivers Tx1 , Tx2 located on the same side of the vehicle and on either side of the opening element are able to communicate with each other via ultra-wideband communication.

[0059] Furthermore, still according to the invention, the activation device D comprises:

[0060] a means M1 for determining the time of flight of a reflected wave originating from a portable device (SD) emitted by the first transceiver Tx1;

[0061] b. means M2 for calculating the radius of a circle centered on the first transceiver according to the flight time, and determining the circumference of the circle where the portable equipment may be located;

[0062] c. means M3 for comparing the curve of the reflected wave originating from the second transmitter with a predetermined received wave curve;

[0063] d. means M4 for detecting the presence of an object in a predetermined area around the two transceivers based on the result of the comparison;

[0064] e. means M5 for calculating the distance between the second transceiver and the presence;

[0065] f. means M6 for locating the portable equipment based on the calculation of the intersection between the calculated distance and the previously determined perimeter;

[0066] g. Means M7 for activating a vehicle function as a function of the position.

[0067] The means M1 for determining the time of flight are able to calculate the round trip time of the waves between the first transceiver Tx1 and the portable equipment SD, also called TOF ("time of flight"), as is known to those skilled in the art. The time of flight thus calculated can be used to determine the distance separating the first transceiver Tx1 and the portable equipment SD.

[0068] Based on this distance, the calculation means M2 determine the circumference of a circle centered at the first transceiver Tx1 , the radius R of this circle being equal to the distance previously calculated based on the time of flight TOF. The portable equipment SD may be located at any point on said circumference C.

[0069] Then, the comparison device M3 compares the curve of the received wave originating from the second transceiver Tx2 emitted by the first transceiver Tx1 with the predetermined received wave curve. In this case, the curve of the received wave is CIR or "channel impulse response". The comparison device M3 includes a device for determining a parameter called CIR ("channel impulse response"), that is, a device for measuring the received wave sampled over time t. It should be noted that the amplitude of the CIR or the phase of the CIR can be used. In this example, the frequency measurement result of the received wave is transformed via an inverse Fourier transform to generate a value in units of time. The amplitude of the CIR is composed of the absolute values ​​of the real and imaginary parts of the value in units of time. The phase of the CIR is composed of the inverse tangent value of the ratio of the imaginary part of the value in units of time divided by the parts of these values. The calculation of the amplitude or phase of the CIR is well known to those skilled in the art and will not be described in further detail herein. The curve of the CIR changing over time can be used to detect any object or existence that may reflect the transmitted wave. Therefore, the peaks in the CIR curve correspond either to waves that were received directly in line of sight with no obstacles, or to waves that were received but reflected by an obstacle in their path.

[0070] According to the present invention, the predetermined reception wave curve comprises a single peak, which corresponds to the presence of the second transceiver Tx2 reflecting the wave.

[0071] If there is an object near the two transceivers Tx1 and Tx2, the object will reflect the wave, thereby generating a second peak on the CIR curve, and then the detection device M4 detects the existence of the object in a predetermined area around the two transceivers Tx1 and Tx2. Figure 2 ), so the distance D' between the second transceiver Tx2 and the object can be determined using the CIR and the occurrence times of the first peak and the second peak.

[0072] This is Figure 5 , which is a graph showing the power spectral density of the propagation channel or the impulse response of each channel (i.e., CIR varying with time t). This type of representation of CIR is known to those skilled in the art and will not be described in further detail herein.

[0073] At the first instant t1, a first peak Pk1 of the reflected wave occurs, which corresponds to the wave reflected by the second transceiver Tx2. The first instant thus corresponds to the round trip flight time required for the wave to propagate twice the distance d1 between the two transceivers Tx1, Tx2.

[0074] At the second instant t2, a second peak Pk2 of the reflected wave occurs, corresponding to the wave reflected by an object located around the two transceivers Tx1, Tx2. The calculation means M5 determine the distance d2 between the second transceiver Tx2 and the object based on the delay Δt between the first instant t1 and the second instant t2.

[0075] Once the circumference of the circle around the first transceiver Tx1 where the portable device SD may be located is determined and the distance d2 separating the object from the second transceiver Tx2 is calculated, the device for locating the portable device SD determines an intersection point I on the circle that is at a distance d2 from the second transceiver Tx2.

[0076] According to the invention, this intersection point I is considered to be the position of the portable equipment SD.

[0077] The activation device M7 triggers the activation of a vehicle function, in this example the unlocking of the driver's door P1 , as a function of the position I of the portable appliance SD.

[0078] Means M1 for determining the time of flight of a wave, means M2 for calculating the radius of a circle centered on the first transceiver, means M3 for comparing the curve of the reflected wave originating from the second transmitter with a predetermined wave curve, means M4 for detecting the presence of an object in a predetermined area around the two transceivers based on the result of the comparison, means M5 for calculating the distance between the second transceiver and the object, means M6 for locating a portable device based on the calculation of the intersection between the calculated distance and the previously determined circumference, and means M7 for activating a vehicle function based on the position are preferably integrated in the form of software into a printed circuit located in the central control unit 10.

[0079] According to the embodiment described below, the central control unit 10 also includes a processor 100 and a memory 101 (see Figure 3 ), the memory stores instructions that allow the processor to be configured to perform certain specific processing operations and, in particular, to implement the steps of the activation method.

[0080] We will now describe Figure 4 The method is shown for activating and unlocking the driver's door P1 of the vehicle V, but the method can also be applied to other vehicle functions or to other opening elements, such as the right front door P2 or the trunk P3 (see Figure 2).

[0081] During a first step E0 , a first transceiver Tx1 transmits ultra-wideband (UWB) waves. These waves are then received and reflected by a portable access equipment SD located in the transmission zone of said first transceiver Tx1 .

[0082] Once these waves are received by the first transceiver Tx1 , the time of flight TOF of the waves is calculated (step E1 ).

[0083] Then, based on the flight time, the distance of the first transceiver Tx1 from the portable equipment is determined. Based on this distance, the circumference C of the circle around the transmitter Tx1 is defined (see Figure 2 )(step E2), the radius R of this circle is equal to said distance. It is then assumed that the portable access equipment SD can be located anywhere on this circumference.

[0084] In the next step (step E3), the wave transmitted by the first transceiver Tx1 is simultaneously received by the second transceiver Tx2.

[0085] Then, the CIR curve of the reception waves originating from the second transceiver Tx2 is determined and compared with a predetermined reception wave curve including only a single peak Pk1 corresponding to the second transceiver Tx2 that may reflect these waves (step E4).

[0086] If a second peak Pk2 is detected on the CIR curve corresponding to the reflection of an object located in a predetermined area around the two transceivers Tx1, Tx2 (step E5), the distance d2 separating the second transceiver Tx2 from the object is calculated based on the delay Δt between the two peaks Pk1 and Pk2 (step E6).

[0087] Then, according to the invention, the point of intersection I between the circumference C of the circle and the line segment of length d2 originating from the second transceiver Tx2 is determined (step E7). According to the invention, the position of this point of intersection I is considered to be the position of the access equipment SD.

[0088] Depending on the position of the intersection point I and whether the intersection point belongs to a predetermined area authorizing the activation of certain vehicle functions, one or more vehicle functions are activated (eg unlocking the door P1 ) (step E8 ).

[0089] The invention thus cleverly allows determining the position of a portable device SD simply by using the reflection of the waves caused by the presence of a user carrying said device and the influence of said reflection on the curve of the received waves when the two transceivers communicate with each other, even when said device is visible only to transceiver Tx1.

[0090] The present invention is particularly noteworthy in that it requires limited resources (in this case software resources), is easy to implement and is inexpensive.

Claims

1. A method for activating a vehicle function using an activation device (D) intended to be fitted on a vehicle, the activation device comprising at least two ultra-wideband (UWB) transceivers (Tx1, Tx2), the at least two ultra-wideband transceivers being located on both sides of an opening element (P1) and on the same side of the vehicle (V), at a predetermined distance (d1) apart and being able to communicate with a portable user equipment (SD), the method being characterized in that the two transceivers (Tx1, Tx2) are adapted so that they can communicate with each other via ultra-wideband communication, and wherein, The method comprises the following steps: a) transmitting waves through at least one first transceiver (Tx1); b) receiving reflected waves originating from the portable device (SD) and determining the time of flight (TOF) of these waves; c) calculating the radius (R) of a circle centered at the first transceiver (Tx1) based on the time of flight (TOF), and determining the circumference (C) of the circle where the portable equipment may be located; d) receiving a reflected wave from the second transceiver (Tx2); e) comparing a curve of the reflected wave received over time (t) (CIR) with a predetermined received wave curve; f) detecting the presence (U) in a predetermined zone (Z1, Z2) around the two transceivers (Tx1, TX2) based on the result of the comparison; i) if a presence is detected, calculating the distance (d2) between the second transceiver (Tx2) and said presence (U); ii) locating the portable device (SD) based on the calculation of the intersection point (I) between said calculated distance (d2) and the previously determined perimeter (C); iii) activating the vehicle function based on the position.

2. The activation method according to the preceding claim, wherein: The curve of the received wave (CIR) corresponds to the impulse response of each channel and wherein the presence is detected by the presence of two consecutive peaks (Pk1, Pk2) in said response.

3. A device (D) for activating a vehicle function, the device being intended to be mounted on a vehicle, the device comprising at least two ultra-wideband (UWB) transceivers (Tx1, Tx2), the at least two ultra-wideband transceivers being located on both sides of an opening element (P1), at a predetermined distance (d1) apart and on the same side of the vehicle (V), capable of communicating with a portable user equipment (SD), the device (D) being characterized in that the two transceivers (Tx1, Tx2) are capable of communicating with each other via ultra-wideband communication, and wherein, The device further comprises: a) means (M1) for determining the time of flight (TOF) of the reflected wave originating from the portable device (SD); b) means (M2) for calculating, from the flight time, the radius (R) of a circle centered on the first transceiver (Tx1), and for determining the circumference (C) of said circle where the portable equipment (SD) may be located; c) means (M3) for comparing the curve (CIR) of the received reflected waves originating from the second transmitter with a predetermined received wave curve; d) means (M4) for detecting the presence of an object in a predetermined zone (Z1, Z2) around the two transceivers (Tx1, Tx2) as a function of the result of the comparison; e) means (M5) for calculating the distance (d2) between the second transceiver (Tx2) and said being (U); f) means (M6) for locating the portable equipment (SD) based on the calculation of the point of intersection (I) between said calculated distance (d2) and the previously determined perimeter (C); g) means (M7) for activating a vehicle function as a function of said position.

4. Activation device (M7) according to the preceding claim, wherein The curve of the received wave (CIR) corresponds to the impulse response of each channel and wherein the means (M4) for detecting the presence of an object are capable of detecting two consecutive peaks (Pk1, Pk2) in said response.

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

6. A motor vehicle (V), wherein: The motor vehicle comprises an activation device (D) as claimed in any one of claims 3 and 4 .

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