FR3043965A1 - METHOD AND COMMUNICATION DEVICE FOR REMOTELY ACTIVATING A FUNCTION OF A MOTOR VEHICLE - Google Patents

Abstract

The present invention relates to a method of communication between a device of a motor vehicle and a user equipment for the remote activation of at least one function of the vehicle, said device comprising an antenna. The method comprises a first step (E1) of transmission or reception by the antenna, over a first time interval, of at least a first electromagnetic wave, whose main component is electric, on a first radiation surface, a second step (E2) of transmission or reception by the antenna, over a second time interval, of at least a second electromagnetic wave, whose main component is magnetic, on a second radiation surface and a step ( E3) communicating with the user equipment via the antenna when said equipment is in the first surface or in the second surface.

Description

The invention relates to the field of localization and relates more particularly to a method and a communication device for the remote activation of a function of a motor vehicle.

In a motor vehicle, it is known to use an omnidirectional radiation antenna to communicate with a user equipment in a predetermined area extending around the vehicle.

Such detection can be achieved using the vehicle lock key or a mobile phone worn by the user.

This detection can be performed in particular to lock the access to the vehicle when the user moves away or to activate a number of functions in the vehicle when the user approaches such as, for example, the unlocking of access to the passenger compartment or adjustment of certain equipment such as, for example, preheating the passenger compartment, adjusting the driver's seat, adjusting the mirrors, lighting the lights, etc.

The radiation pattern of such an antenna in the horizontal plane is not circular but varies around a 360 ° average radius generally presenting two contiguous lobes.

Also, at equal distance from the antenna, a user can be in the antenna coverage area for a first direction and out of the antenna coverage area for a second direction, corresponding for example to a position located between the two lobes, which can prevent communication between the vehicle and the user equipment and therefore has major disadvantages.

To partially correct this problem, a known solution, called antenna diversity, consists in using a first antenna and a second antenna arranged perpendicularly and that alternately emit electromagnetic waves so that their radiation patterns are superimposed, thereby compensating for an antenna. at least partially the defects of the other antenna.

The electromagnetic waves emitted by the first antenna and the second antenna both have a predominantly electrical component or both a predominantly magnetic component. In the latter case, the antennas may be composed of metal elements to form antennas called "3D".

The antennas emit alternately at a sufficiently high frequency to ensure that the user is substantially in the same place during two successive transmissions, respectively of the first antenna and the second antenna.

In order to simplify the architecture of the system and in particular the synchronization of the antennas so that they emit alternately, it is known to integrate the two antennas on the same printed circuit board ("Printed Circuit Board" or PCB in English). Such integration may, however, generate a coupling phenomenon between the two antennas.

Indeed, each antenna has its own radiation and this radiation influences the other antenna, which reduces the overall radiation surface of the system and therefore its effectiveness.

In addition, the use of two antennas makes the architecture of the electrical circuit complex and expensive. Indeed, the diversity of antennas involves a significant occupation on the printed circuit, which results in an integration into the vehicle which can be complex and expensive.

In addition, the use of predominantly 3D-type magnetic antennas increases the cost of the system, which has another disadvantage. The aim of the invention is to overcome at least part of these disadvantages by proposing a solution which is at the same time simple, reliable and effective while making it possible to cover a large area of radiation. To this end, the invention firstly relates to a method of communication between a device of a motor vehicle and a user equipment for the remote activation of at least one function of the vehicle, said device comprising an antenna configured both for transmitting and receiving electromagnetic waves, said method comprising: a first step of transmitting or receiving by the antenna, on a first time interval and on a first radiation surface, of least a first electromagnetic wave whose main component is electrical, • a second step respectively of emission or reception by the antenna, over a second time interval, of at least a second electromagnetic wave whose main component is magnetic, on a second radiation surface at least partly complementary to the first surface so that the total area of ra yonnement corresponding to the superposition of the first surface and the second surface is greater than the first surface taken alone or the second surface taken alone, • a step of communication with the user equipment via the antenna when said equipment is in the first surface or in the second surface.

The term "principal component" means that the maximum amplitude of this component represents more than 50% of the maximum amplitude of the emitted field.

By the terms "transmission or reception" and "transmit or receive" means in this description transmission and / or reception and transmit and / or receive. The use of a single antenna makes it possible to eliminate the coupling phenomenon (generated by the use of several antennas). In addition, the use of a single predominantly electric or magnetic antenna provides two radiation surfaces, defining the radiation zone, the superposition is wider than each of the two surfaces taken separately, which improves the size and the accuracy of the coverage of the antenna and ensures communication with a user equipment located in one of the radiation surfaces but not in the other.

Finally, the use of a single antenna, and therefore the absence of coupling, provides greater accuracy and gain than those obtained by a system consisting of two coupled antennas while advantageously improving the radio radiation surface.

According to one aspect of the invention, the first generation step and the second generation step are performed alternately and successively, which allows to alternate the first time intervals and the second time intervals.

Preferably, the first generation step and the second generation step are performed alternately at a frequency greater than a predetermined threshold so that communication is possible between the user equipment and the vehicle in order to activate to distance at least one function of the vehicle. Advantageously, the antenna emits alternately at a sufficiently high frequency to ensure that the user is substantially in the same place during two successive transmissions, respectively on the first time interval and on the second time interval. The frequency switching threshold is preferably greater than or equal to the transmission frequency of the frames exchanged between the vehicle and the device. For example, if the signals between the vehicle and the device are transmitted in the form of a "burst" comprising three frames spaced by 90 ms and a duration (per frame) of 10 ms, it will be necessary for the switching to be performed at least all the 100 ms.

Advantageously, the method furthermore comprises a step of activating at least one function of the vehicle following a communication between the user equipment and the vehicle, for example in order to unlock the access to the passenger compartment or to carry out the adjustment. certain vehicle equipment such as, for example, preheating the passenger compartment, adjusting the driver's seat, adjusting the mirrors, lighting the lights, etc. The invention also relates to a device intended to be mounted in a motor vehicle for communication with an equipment of a user of said vehicle for the remote activation of at least one function of the vehicle, said device comprising: • a single antenna configured to transmit or receive at least a first electromagnetic wave, the main component of which is electrical, on a first radiation surface and at least a second electromagnetic wave, the main component of which is magnetic, on a second radiation surface at least in part complementary to the first surface so that the total area of radiation corresponding to the superposition of the first surface and the second surface is greater than the first surface taken alone or the second surface taken alone, a management module configured to to control said antenna so that it alternatively transmits or receives the first electromagnetic wave and the second electromagnetic wave, • a power supply module configured to supply the management module and the antenna with electrical energy, and • a communication module configured to communicate with the equipment of user via the antenna when said equipment is in the first surface or in the second surface. The use of a single antenna requires fewer components than a solution with two antennas, which advantageously makes the device less bulky.

Preferably, the management module is configured to adapt the output impedance of the antenna so that it alternately generates the first electromagnetic wave and the second electromagnetic wave. To this end, in a preferred embodiment, the management module comprises a first variable capacitance comprising a first terminal, electrically connected to a ground, and a second terminal, a first inductive coil comprising a first terminal and a second terminal and a terminal. second variable capacitance comprising a first terminal and a second terminal electrically connected to the ground, the second terminal of the first variable capacitance being electrically connected to the first terminal of the first inductive coil, the second terminal of the first inductive coil being electrically connected to the first terminal of the second variable capacitance and on the antenna.

Advantageously, the management module further comprises an input capacitor connected, on the one hand, to the power supply module and, on the other hand, to the first terminal of the first inductive coil.

In another embodiment, the antenna comprises a first branch and a second branch, said first branch comprising a first diode, a second inductive coil and a first resistor connected in series, said second branch comprising a second diode, a third coil inductive and a second resistor connected in series. The invention also relates to a motor vehicle comprising a communication device as presented above. The invention relates to a system comprising a motor vehicle as presented above and at least one user equipment configured to communicate with the vehicle communication device. Other features and advantages of the invention will become apparent from the following description given with reference to the appended figures given by way of non-limiting examples and in which identical references are given to similar objects. - Figure 1 schematically illustrates an embodiment of the system according to the invention. - Figure 2 schematically illustrates the device according to the invention. - Figure 3 schematically illustrates an embodiment of the device according to the invention. - Figure 4 schematically illustrates an embodiment of the method according to the invention. FIG. 5 schematically illustrates an example of a radiation pattern obtained with the device according to the invention.

The system according to the invention will firstly be described hereinafter with reference to FIG.

The system 1 comprises a vehicle 2 and a vehicle 3 carried by a user (not shown) of the vehicle 2 located, in this illustrative example, in a predetermined area 4 around the motor vehicle 2.

The vehicle 2 comprises a device 20 able to communicate with the user equipment 3 in order to remotely activate one or more functions of the vehicle 2 such as, for example, the unlocking of access to the passenger compartment or the adjustment certain equipment of the vehicle 2 such as, for example, a preheating of the passenger compartment, the adjustment of the driver's seat, the adjustment of the mirrors, the lighting of lighting etc.

With reference to FIG. 2, the communication device 20 comprises a single antenna 210, a management module 220, a power supply module 230 and a communication module 240. The antenna 210 is configured to transmit and receive at least a first electromagnetic wave, whose main component is electric, on a first radiation surface (it is said that the antenna operates in "electric mode"). The antenna 210 is also configured to transmit and receive at least a second electromagnetic wave, the main component of which is magnetic, on a second radiation surface (it is said that the antenna operates in "magnetic mode").

The second radiating surface is at least partially complementary to the first surface so that the total area corresponding to the superposition of the first surface and the second surface is greater than the first surface taken alone or the second surface taken separately .

In the example of FIG. 1, it is considered that the superposition of the first surface and the second surface corresponds substantially to the predetermined zone 4.

The management module 220 is configured to control the antenna 210 so that it emits or passively alternatively receives the first electromagnetic wave, over a first time interval, and the second electromagnetic wave, over a second time interval, subsequent to the first time interval.

In the preferred embodiment illustrated in Figure 3, the management module 220 is in the form of an impedance matching structure, common to both modes of operation of the antenna. This common structure comprises a fixed input capacitance C0, a first variable capacitance Ci, a coil L1s a second variable capacitance C2, a switch h and control means of the switch h (not shown).

The fixed input capacitance C0 is connected by a first terminal to the power supply module 230 and by its second terminal to a first terminal of the first variable capacitance Ci and to a first terminal of the coil L1.

The first variable capacitance Ci is connected to the ground M by its second terminal.

The second terminal of the coil is connected to a first terminal of the second variable capacitance C2, to the antenna 210 and to a first terminal of the switch h.

The second variable capacitance C2 is connected to the ground M by its second terminal. The output impedance of this common structure is materialized by an impedance Zc disposed between the second terminal of the switch h and the ground M. This impedance Zc can be an adaptation circuit or a direct connection to a mass-type load allowing a preferred magnetic radiation, for example a predominantly magnetic radiation, that is to say whose magnetic component represents more than 50% of the total electromagnetic wave. By way of example, the following values may be used: 0.1 pF <C0 <1 nF, 0.1 pF <C <1 nF, 0.1 pF <C2 <1 nF, 0.1 nH <L, <1 μΗ.

The common structure allows the adaptation of the antenna 210 both when operating in the antenna and magnetic antenna so that it covers the entire Smith chart. More precisely, the adapted choice of the values of the coil L1s of the first variable capacitance C! and the second variable capacitance C2 makes it possible to adapt the antenna 210 regardless of the output impedance Zc, judiciously using a single switch which reduces the dimensions of the device 20.

The power supply module 230 is configured to supply the management module 220 and the antenna 210 with electrical energy.

The communication module 240 is configured to communicate with the user equipment 3 via the antenna 210 when said equipment 3 is in the first radiation surface or in the second radiation surface. The invention will now be described in its implementation with reference to FIG. 4.

In a first step E1, the antenna 210 transmits or receives, on a first time slot, at least a first electromagnetic wave, whose main component is electrical, on a first radiation surface, corresponding to a first radiation pattern.

Subsequently, in a second step E2, the antenna 210 transmits or receives, over a second time interval, at least one second electromagnetic wave, whose main component is magnetic, on a second radiation surface.

This second radiation surface is at least partially complementary to the first surface and corresponds to a second radiation pattern which is at least partly complementary to the first radiation pattern. The antenna 210 is controlled by the management module 220 in transmission but the management module 220 is passive in receiving electromagnetic waves from the user equipment 3. The step E1 is then performed again, consecutively to the step E2 and so on as long as the device is in operation. In other words, the first step E1 and the second step E2 are performed alternately.

In a communication step E3, the communication module 240 receives messages from the user equipment 3 or sends messages to the user equipment 3 via the antenna 210 on the first time slot or on the second time interval when the equipment 3 is respectively in the first surface or in the second surface.

The total area of radiation of the antenna 210 then corresponds to the superposition of the first surface and the second surface which is greater than the first surface taken alone or the second surface taken alone. The alternation of waves with a predominantly electric component and predominantly magnetic component waves, advantageously implemented by the impedance matching structure of the management module 220, makes it possible to cover radiation zones reached by one of them. waves but not the other.

FIG. 5 illustrates an example of radiation diagrams (gain G as a function of the angle α in the electrical mode E and the magnetic mode M) obtained with the communication device 20 according to the invention.

In this example, the curve E corresponds to the operation of the antenna 210 in electrical mode and has a non-electromagnetic wave reception point indicated by the arrow F. The curve M corresponds to the operation of the antenna 210 in magnetic mode.

Thus, if a message is transmitted by the antenna 210 over a second time interval at the angle corresponding to the non-reception point F while the user equipment 3 is listening to the antenna 210 in electrical mode, the message will not be received by the user equipment 3.

When automatic switching of the antenna 210 from the electrical mode to the magnetic mode, the user equipment 3 can then receive the message transmitted by the antenna 210, the radiation pattern of the curve M having higher performance than that of curve E at point F. The inverse reasoning is also valid, that is to say when the radiation pattern of the curve E has higher performances than that of the curve M. The use of a single antenna 210 alternatively electrical and magnetic allows both to eliminate the coupling phenomenon generated by the use of several antennas and to obtain two complementary radiation patterns that alternate so as to allow communication with a user equipment 3 on a surface of radio radiation 4 important while increasing the accuracy of the device.

In addition, the use of a single antenna 210 provides greater accuracy and gain than those obtained by a system of two coupled antennas, which improves the quality of communication.

Finally, it should be noted that the present invention is not limited to the examples described above and is capable of numerous variants accessible to those skilled in the art.

In particular, the shapes and dimensions of the antenna 10 and radiation patterns as shown in the figures so as to illustrate an exemplary embodiment of the invention, can not be interpreted as limiting.

Claims (10)

A method of communication between a device (20) of a motor vehicle (2) and a user equipment (3) for remote activation of at least one function of the vehicle (2), said device (20) ) comprising an antenna (210) configured both for transmitting and receiving electromagnetic waves, said method being characterized in that it comprises the following steps: a first step (E1) of transmission or reception by the antenna (210), on a first time interval and on a first radiation surface, at least a first electromagnetic wave whose main component is electric, • a second step (E2) respectively transmission or reception by the antenna (210), over a second time interval, of at least a second electromagnetic wave, the main component of which is magnetic, on a second radiation surface at least partly complementary to the first surface so that the total area of radiation corresponding to the superposition of the first surface and the second surface is greater than the first surface taken alone or the second surface taken separately, a step (E3) of communication with the user equipment (3) via the antenna (210) when said equipment (3) is in the first surface or in the second surface. 2. Method according to claim 1, characterized in that the first generation step (E1) and the second generation step (E2) are performed alternately and successively. 3. Method according to one of the preceding claims, characterized in that said method further comprises a step of activating at least one function of the vehicle (2) following a communication between the user equipment (3) and the vehicle (2). Device (20) for mounting in a motor vehicle (2) for communication with equipment (3) of a user of said vehicle (2) for remote activation of at least one vehicle function ( 2), said device (20) being characterized in that it comprises: • a single antenna (210) configured to transmit or receive at least a first electromagnetic wave, the main component of which is electrical, on a first radiation surface and at least one second electromagnetic wave, the main component of which is magnetic, on a second radiation surface at least partially complementary to the first surface so that the total area of radiation corresponding to the superposition of the first surface and the second surface greater than the first surface alone or the second surface alone, • a management module (220) configured to control der said antenna (210) so that it alternately emits or receives the first electromagnetic wave and the second electromagnetic wave, • a supply module (230) configured to supply the management module (220) and the antenna (210) with electrical power, and • a communication module (240) configured to communicate with the user equipment (3) via the antenna (210) when said equipment (3) is in the first surface or in the second surface. 5. Device (20) according to claim 4, characterized in that the management module (220) is configured to adapt the output impedance of the antenna (210) so that it alternately generates the first electromagnetic wave and the second electromagnetic wave. 6. Device (20) according to claim 5, characterized in that the management module (220) comprises a first variable capacitance (Ci) comprising a first terminal, electrically connected to a ground (M), and a second terminal, a first inductive coil (U) comprising a first terminal and a second terminal and a second variable capacitance (C2) comprising a first terminal and a second terminal electrically connected to the ground (M), the second terminal of the first variable capacitance (C ^ being electrically connected to the first terminal of the first inductive coil (L,), the second terminal of the first inductive coil (U) being electrically connected to the first terminal of the second variable capacitance (C2) and the antenna (210). ). 7. Device (20) according to claim 6, characterized in that the management module (220) further comprises an input capacitor (C0) connected, on the one hand, to the power supply module (230) and, on the other hand, at the first terminal of the first inductive coil (L,). 8. Device (20) according to any one of claims 6 and 7, characterized in that the antenna (210) comprises a first branch and a second branch, said first branch comprising a first diode, a second inductive coil and a first resistor connected in series, said second branch comprising a second diode, a third inductive coil and a second resistor connected in series. 9. Vehicle (2) automobile characterized in that it comprises a device (20) for communication according to any one of claims 4 to 8. 10. System (1) characterized in that it comprises a motor vehicle (2) according to claim 9 and at least one user equipment (3) configured to communicate with the communication device (20), according to one any of claims 4 to 8 of the vehicle (2).