WO2019223938A1

WO2019223938A1 - On-board system, identifier and method for assessing a distance

Info

Publication number: WO2019223938A1
Application number: PCT/EP2019/059655
Authority: WO
Inventors: Laurent Petel
Original assignee: Valeo Comfort And Driving Assistance
Priority date: 2018-05-23
Filing date: 2019-04-15
Publication date: 2019-11-28
Also published as: FR3081637A1; FR3081637B1

Abstract

The invention relates to an on-board system (15) which comprises an electronic unit (11) and a first wireless communication circuit (12). The electronic unit (11) is designed to implement a communication protocol according to which the first wireless communication circuit (12) exchanges data with a second wireless communication circuit (22) during time slots separated by a predetermined time interval. The electronic control unit is also designed to trigger, after each of a plurality of said data exchanges, an exchange, between the first wireless communication circuit (12) and the second wireless communication circuit (22), of at least one electromagnetic signal used to assess the distance (d) separating the first wireless communication circuit (12) from the second wireless communication circuit (22). A corresponding identifier and a method for assessing a distance are likewise described.

Description

Embedded system, identifier and method for evaluating a distance

TECHNICAL FIELD TO WHICH THE INVENTION REFERS

The present invention generally relates to the field of wireless exchanges between an onboard system, for example equipping a vehicle, and an identifier associated for example with this vehicle.

It relates more particularly to an on-board system, an identifier and a method of evaluating a distance.

BACKGROUND

Passive Entry (Passive Starf) type systems are known in which the implementation of a feature (such as unlocking the doors of a vehicle or starting such a vehicle) is conditioned by the presence near the vehicle of an identifier (usually worn by the user of the vehicle).

It is necessary in this context in particular to evaluate at each moment the distance separating the identifier and the vehicle in order to determine on this basis the functionalities to possibly implement.

It has thus been proposed in document FR 3,044,100 to evaluate this distance by means of electromagnetic signals exchanged between communication modules equipping respectively the vehicle and the identifier, and furthermore designed to establish a wireless exchange link. in accordance with a communication protocol.

OBJECT OF THE INVENTION

In this context, the present invention proposes an embedded system comprising an electronic unit and a first wireless communication circuit, characterized in that the electronic unit is designed to implement a communication protocol according to which the first communication circuit without wire performs data exchange with a second wireless communication circuit for time slots separated by a predetermined time interval, and for triggering, after each of a plurality of said data exchanges, an exchange, between the first communication circuit wireless and the second wireless communication circuit, at least one electromagnetic signal used to evaluate the distance between the first wireless communication circuit and the second wireless communication circuit. The electromagnetic signals exchanged in order to evaluate the distance between the two wireless communication circuits are thus clocked and do not further interfere with the data exchanges carried out within the time slots defined by the communication protocol.

Other non-limiting and advantageous features of such an embedded system, taken individually or in any technically possible combination, are as follows:

the communication protocol is of the BLE type (for "Bluetooth Low Energy");

the exchange of the electromagnetic signal is triggered at the end of the data exchange concerned;

the electronic unit is adapted to control the first wireless communication circuit so that the first wireless communication circuit exchanges a plurality of electromagnetic signals at different frequencies with the second wireless communication circuit, and / or for evaluating said distance on the basis of measurements relating to said electromagnetic signals;

said measurements are phase measurements of the electromagnetic signal concerned;

said data comprises configuration data of said electromagnetic signals;

the electronic unit is adapted to determine an ordered list of channels according to the configuration data and / or to control the first wireless communication circuit the exchange of electromagnetic signals successively in each of the channels of the ordered list of channels;

said data (data exchanged between the first wireless communication circuit and the second wireless communication circuit) are encrypted (for example because of the use of the aforementioned BLE type protocol).

The invention also proposes an identifier comprising a control unit and a wireless communication circuit, characterized in that the control unit is designed to implement a communication protocol according to which the wireless communication circuit carries out exchanges. of data with another wireless communication circuit for time slots separated by a predetermined time interval, and for triggering, after each of a plurality of said data exchanges, an exchange between the wireless communication circuit and the other wireless communication circuit, of at least one electromagnetic signal used to evaluate the distance between the wireless communication circuit and the other wireless communication circuit.

According to one possible embodiment, the control unit may be designed to control the wireless communication circuit so that the wireless communication circuit exchanges a plurality of electromagnetic signals at different frequencies with the other communication circuit. wirelessly, and / or for evaluating said distance on the basis of measurements relating to said electromagnetic signals.

As already indicated with regard to the onboard system, provision may furthermore be made for said data to comprise configuration data of said electromagnetic signals. Said data may furthermore be encrypted (for example because of the use of the aforementioned BLE type protocol).

The invention also proposes a method of evaluating a distance separating a first wireless communication circuit fitted to an on-board system and a second wireless communication circuit equipping an identifier, characterized in that, data exchanges between the first wireless communication circuit and the second wireless communication circuit being implemented during time slots separated by a predetermined time interval according to a communication protocol, the evaluation method comprises, after each of a plurality of said data exchange, a step of triggering an exchange, between the first wireless communication circuit and the second wireless communication circuit, of at least one electromagnetic signal used to evaluate said distance.

It is possible for the first wireless communication circuit to exchange a plurality of electromagnetic signals at different frequencies with the second wireless communication circuit, the method then possibly comprising a step of evaluating said distance on the basis of measurements relating to said electromagnetic signals.

Said data may further comprise configuration data of said electromagnetic signals and / or be exchanged encrypted (for example because of the use of the BLE protocol).

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The following description with reference to the accompanying drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be achieved.

In the accompanying drawings:

- Figure 1 shows schematically the main elements of a system in which the invention can be implemented; and

FIG. 2 represents an exemplary method implemented in the system of FIG. 1.

Figure 1 shows schematically the main elements of a system in which the invention can be implemented.

Such a system comprises a vehicle 10, here a motor vehicle, and an identifier 20, for example a vehicle access key or badge 10 (or, alternatively, a user terminal, such as a mobile phone or a smartphone - or "smartphone" according to the English application commonly used, provided with rights of access to the vehicle 10).

The vehicle 10 is equipped with an onboard system 15 comprising in particular an electronic control unit 11 and a communication circuit 12.

The electronic control unit 11 comprises for example a microprocessor and at least one memory, for example a rewritable non-volatile memory. The memory notably stores program instructions which, when executed by the microprocessor, enable the electronic control unit 11 to implement the method described below with reference to FIG. 2. The memory also stores values or parameters used during these processes, for example measured phase values F, (when the electronic control unit 11 which determines characteristic measurements of an electromagnetic signal received by the communication circuit as explained later).

The memory of the electronic control unit 1 1 also stores a cryptographic key K (which has for example been registered within the electronic control unit 1 1 during its manufacture).

Alternatively, the electronic control unit 11 could be realized in the form of a specific application integrated circuit (or ASIC for "Application Specifies Integrated Circuit").

The communication circuit 12 is designed to establish a wireless link with other electronic devices, here a connection of "Bluetooth Low Energÿ" (or "BLE") type, the communication circuit 12 is therefore especially designed to transmit and receive electromagnetic signals (typically with a frequency greater than 1 MHz or even 500 MHz), here in the 2.4 GHz band.

The identifier 20 is generally worn by a user of the vehicle 10 and allows the control of certain functionalities of the vehicle 10 (for example the unlocking of the doors of the vehicle 10), especially when approached from the vehicle 10. The identifier 20 may optionally further comprising control buttons, with which the user can control at least some of the aforementioned features or other features of the vehicle 10.

The identifier 20 comprises a control unit 21 and a communication circuit 22.

The control unit 21 is for example made by means of a microprocessor and at least one memory, for example a rewritable non-volatile memory. The memory notably stores program instructions which, when executed by the microprocessor, enable the control unit 21 to implement the method described below with reference to FIG. 2. The memory also stores values or parameters used during these methods, for example measured phase values F, (when it is the control unit 21 which determines characteristic measurements of an electromagnetic signal received by the communication circuit 22, as explained more far).

The memory of the control unit 21 also stores the cryptographic key K. In the case where the identifier 20 is a key (or key) for access to the vehicle, the cryptographic key K has for example been written in the memory of the control unit 21 during the manufacture of the identifier 20. In the variant mentioned above where the identifier 20 is a user terminal, the cryptographic key K has for example been received from a remote server and stored during a subscription phase to a service of control of the functionalities of the vehicle by means of the user terminal.

Alternatively, the control unit 21 could be made in the form of a specific application integrated circuit.

The communication circuit 22 is designed to establish a wireless link (here of "Bluetooth Low Energy" or "BLE") type with other electronic devices, in particular with the electronic control unit 1 1 of the vehicle 10 via the The communication circuit 22 is also designed to transmit and receive electromagnetic signals (typically with a frequency greater than 1 MHz or even 500 MHz), here in the 2.4 GHz band.

Thanks to the wireless link thus established between the communication circuit 12 of the on-board system 15 of the vehicle 10 and the communication circuit 22 of the identifier 20, data D can be exchanged between the electronic control unit 11 of the system. embedded vehicle 15 and the control unit 21 of the identifier 20, as explained below.

The electromagnetic signals exchanged between the communication circuits 12, 22 can also be used to evaluate the distance d between the identifier 20 and the vehicle 10 (precisely the distance d between the communication circuits 12, 22), as also explained more far.

FIG. 2 represents an example of a method implemented within the framework of the system which has just been described.

This method starts at step E2 during which the communication circuit 22 of the identifier 20 transmits at least one advertisement frame ADV ("advertising packet" according to the English terminology), in accordance with the BLE protocol.

For example, such announcement frames ADV are sent periodically by the communication circuit 22 of the identifier 20 (under the control of the control unit 21 of the identifier 20) as long as no response is received from a communication partner (as explained below in step E8).

The ADV announcement frames are here of the ADVJND type: they are announcement frames indicating the availability for a connection and not specifically directed to a communication partner (or "connectable undirected advertising event" according to the English terminology ).

The ADV announcement frames transmitted by the communication circuit 22 of the identifier 20 may include data, including data Identification code ID of the identifier 20. According to one conceivable variant, the announcement frames ADV may furthermore comprise at least some of the configuration data mentioned below.

When the vehicle 10 is sufficiently close to the identifier 20 (which occurs when the carrier of the identifier 20 approaches the vehicle 10), the communication circuit 12 of the on-board system 15 of the vehicle 10 receives the frame of the vehicle. ADV announces and signals to the electronic control unit 11 the arrival of this ADV announcement frame (step E4). The communication circuit 12 also transmits at this stage the data possibly included in the advertisement frame ADV (in particular the identification data ID of the identifier 20) to the electronic control unit 11.

The electronic control unit 1 1 can then control the communication circuit 12 to respond to the announcement frame ADV sent by the identifier 20, typically by sending a CONN_REQ connection request to the communication circuit 22 of the identifier 20 (step E6).

According to one possible embodiment, the transmission of the CONN_REQ connection request by the communication circuit 12 (on the order of the electronic control unit 11) may, however, be conditioned by the presence of the identification data ID of the identifier 20 within a list of previously paired identifiers (this list being stored in the memory of the electronic control unit 11, the identification data of a given identifier being added in this list by means of a specific matching process).

The connection request CONN_REQ notably includes data CONNJNT defining the time interval I between time slots dedicated to the data exchanges between the communication circuits 12, 22 during the requested connection. This time interval I is referred to as "Connection Intervat" according to the aforementioned BLE communication protocol.The time interval I used in a given system is predefined by the system designer, the data CONNJNT defining the time interval I are thus for example stored in the memory (non-volatile) of the electronic control unit 1 1 to be transmitted in step E6 as indicated above In practice, in the application envisaged here, the interval time I is for example between 100 ms and 300 ms. The communication circuit 22 of the identifier 20 receives the connection request CONN_REQ in the step E8 and a connection between the on-board system 15 and the identifier 20 can thus be established via the communication circuit 12 of the on-board system 15 and the communication circuit 22 of the identifier 20, in accordance with the communication protocol concerned (here the BLE protocol already mentioned).

Within the framework of this connection established according to the communication protocol concerned, are provided, as already indicated, time slots dedicated to data exchanges D (represented by steps E10 and E12 in FIG. 2) between the communication circuit 12 of the system embedded circuit 15 and the communication circuit 22 of the identifier 20.

According to one conceivable embodiment, the data D exchanged between the identifier 20 and the embedded system 15 during the steps E10, E12 are encrypted (typically by means of an encryption cryptographic algorithm, for example using the shared cryptographic key K by the electronic control unit 1 1 and the control unit 21 as already indicated) during their exchange between the communication circuit 12 of the embedded system 15 and the communication circuit 22 of the identifier 20. The encryption used is for example that provided in the context of the relevant data exchange protocol D, here the BLE protocol.

The data D exchanged between the identifier 20 and the on-board system 15 (that is to say precisely between the control unit 21 and the electronic control unit 11) comprises in particular here configuration data CONF of electromagnetic signals. exchanged between the communication circuits 12, 22 to evaluate the distance d between the communication circuits 12, 22 (as described below with reference to steps E14 and 16). As already indicated, this configuration data CONF can be transmitted encrypted.

For example, it can be provided that these configuration data CONF are transmitted from the electronic control unit 11 to the control unit 21. However, at least some of the configuration data CONF could be transmitted from the control unit 21. command 21 to the electronic control unit 1 1.

CONF configuration data include for example at least one of the following data:

a description (for example a frequency value) of each of the channels that can be used to exchange the electromagnetic signals used to evaluate the distance d separating the communication circuits 12, 22;

a mapping of these different channels (defining for example which channels are used among all the usable channels);

a list defining an ordered sequence of said channels;

- a number of channels to jump;

- a seed (or "seed" according to the Anglo-Saxon name).

For example, it can be provided that the configuration data CONF is exchanged (as has just been indicated) at least during the first time slot of data exchange D (after establishment of the connection), so that the embedded system 15 and the identifier 20 can implement the electromagnetic signal exchanges from the first pass to steps E14, E16 as described below. Some configuration data CONF can however also be exchanged during the subsequent data exchange time slots D, for example to update the configuration of the electromagnetic signals exchanged.

In the example described here, thanks to the exchange of CONF configuration data, the electronic control unit 1 1 of the onboard system 15 and the control unit 21 of the identifier 20 can each determine the same ordered sequence of channels to use.

According to a first example that can be envisaged, this ordered sequence is determined by a list defining this sequence and included in the configuration data CONF as already indicated. In this case, it is possible for the list to be determined by random selection by a communication partner (for example the electronic control circuit 11) and transmitted to the other partner of the communication (here the control circuit 21) at the other end. within CONF configuration data.

According to a second example that can be envisaged, this ordered sequence is determined by successive jumps of a number of channels defined by the configuration data CONF (from an initial channel which may also be defined by the CONF configuration data).

According to a third example that can be envisaged, this ordered sequence is determined by means of a pseudo-random number generator (or PRNG for "pseudo random number generato") using for example a secret (shared between the electronic control unit 1 1 and the control unit 21, such as the cryptographic key K or another cryptographic key stored both within the electronic control unit 11 and the control unit 21) and a seed included in the configuration data CONF as already indicated. for example a linear congruence generator, a multiplicative linear congruence generator, a Tausworthe generator or a Fibonacci generator.

At the end of the data exchanges D in the time slot provided by the communication protocol (here the BLE protocol), that is to say at the end of this time slot, the electronic control unit 11 (or, alternatively, the control unit 21) triggers (between the communication circuit 12 and the communication circuit 22) an exchange of at least one electromagnetic signal R, determined in accordance with at least a portion of the aforementioned CONF configuration data, here on a channel of the aforementioned ordered list of channels (steps E14 and E16).

The electronic control unit 1 1 thus controls for example the emission of this electromagnetic signal R by the communication circuit 12; the control unit 21 can then obtain a measurement (for example a measurement of phase F,) characteristic of this electromagnetic signal R as detected (that is to say, received) by the communication circuit 22. (As a variant it could be the control unit 21 which controls the emission of the electromagnetic signal R by the communication circuit 22 and the electronic control unit 11 which obtains a characteristic measurement of the electromagnetic signal R received by the communication circuit 12 .)

According to one possible embodiment, it is possible during steps E14 and E16 to exchange several electromagnetic signals R used to evaluate the distance d separating the communication circuits 12, 22 (these electromagnetic signals respectively having different frequencies in practice). for example, electromagnetic signals transmitted successively on several successive channels of the aforementioned ordered list of channels.

After this exchange of electromagnetic signals, the electronic control unit 1 1 monitors (for example by means of a counter managed within the electronic control unit 1 1) the expiration of the time interval I (with respect to the beginning of the previous data exchange time slot D, represented by step E10 in FIG. 2). This waiting time is represented by step E18 in FIG.

At the expiry of the time interval I, the electronic control unit 11 opens a new data exchange slot D between the communication circuit 12 of the on-board system 15 and the communication circuit 22 of the identifier 10. note here that the communication circuit 22 is prepared for this new time slot of exchange because the control unit 21 has received the value of the time interval I (defined by the data CONNJNT) with the connection request CONN_REQ in step E8 described above. The method thus closes at step E10 (for the electronic control unit 1 1) and at the step E12 (for the control unit 21) as represented in FIG. 2.

During the process of FIG. 2, the steps E14, E16 for exchanging at least one electromagnetic signal R are thus implemented repeatedly (following each time slot of data exchange D) so that a plurality of electromagnetic signals R are exchanged (in practice at respectively different frequencies) between the communication circuits 12, 22 and that characteristic measurements of these electromagnetic signals (for example F phase measurements) are obtained by the unit. electronic control 1 1 and / or by the control unit 21.

In the example described here, the electromagnetic signals R are successively exchanged (during the different iterations of the steps E14, E16) on the different channels of the above-mentioned ordered list (in the order indicated by this ordered list).

The electronic control unit 11 (or alternatively the control unit 21) can thus evaluate the distance d between the communication circuit 12 and the communication circuit 22 on the basis of the characteristic measurements obtained.

For example, reference may be made to the aforementioned patent application FR 3,044,100 for more details regarding this evaluation.

This evaluation is for example based on the fact that, for a given distance d between the communication circuits 12, 22, the phases Fi, F ₂ respectively measured in reception for two electromagnetic signals of respective frequencies f ₁ , f ₂ (which correspond to two distinct channels) are linked by the relation:

d = o (F ₂ - Fi) / [2tt (ί ₂ - fi)],

where is the celerity of electromagnetic waves.

Thus, on the basis of a plurality of frequency pairs f, measured phase F ,, it is possible to evaluate the distance separating the communication circuits 12, 22 by determining the slope of a regression line associated with the defined points. respectively by these pairs frequency f, - measured phase F ,.

Claims

An on-board system (15) comprising an electronic unit (1 1) and a first wireless communication circuit (12), characterized in that the electronic unit (1 1) is designed to implement a communication protocol according to wherein the first wireless communication circuit (12) performs data exchanges (D) with a second wireless communication circuit (22) for time slots separated by a predetermined time interval, and for triggering, after each a plurality of said data exchanges (D), an exchange, between the first wireless communication circuit (12) and the second wireless communication circuit (22), of at least one electromagnetic signal (R) used to evaluate the distance (d) separating the first wireless communication circuit (12) and the second wireless communication circuit (22).

2. Embedded system according to claim 1, wherein the exchange of the electromagnetic signal (R) is triggered at the end of the data exchange (D) concerned.

An on-board system according to claim 1 or 2, wherein the electronic unit (1 1) is adapted to control the first wireless communication circuit (12) so that the first wireless communication circuit (12) exchanging a plurality of electromagnetic signals (R) at different frequencies with the second wireless communication circuit (22), and for evaluating said distance (d) based on measurements of said electromagnetic signals (R).

4. Embedded system according to claim 3, wherein said measurements are phase measurements of the electromagnetic signal (R) concerned.

5. Embedded system according to one of claims 1 to 4, wherein said data (D) comprises configuration data (CONF) of said electromagnetic signals (R).

An on-board system according to claim 5, wherein the electronic unit (11) is adapted to determine an ordered list of channels according to the configuration data (CONF) and to control the first wireless communication circuit (12). exchanging electromagnetic signals (R) successively in each of the channels of the ordered list of channels.

7. Embedded system according to one of claims 1 to 6, wherein said data (D) are encrypted.

8. Identifier (20) comprising a control unit (21) and a wireless communication circuit (22), characterized in that the control unit (21) is designed to implement a communication protocol according to which the wireless communication circuit (22) performs data exchange (D) with another wireless communication circuit (12) for time slots separated by a predetermined time interval, and for triggering, after each of a plurality of said data exchange (D), an exchange, between the wireless communication circuit (22) and the other wireless communication circuit (12), of at least one electromagnetic signal (R) used to evaluate the distance (d) ) separating the wireless communication circuit (22) and the other wireless communication circuit (12).

An identifier according to claim 8, wherein the control unit (21) is adapted to control the wireless communication circuit (22) so that the wireless communication circuit (22) exchanges a plurality of signals electromagnetically (R) at different frequencies with the other wireless communication circuit (12), and for evaluating said distance (d) based on measurements of said electromagnetic signals (R).

An identifier according to claim 8 or 9, wherein said data (D) comprises configuration data (CONF) of said electromagnetic signals (R).

An identifier according to one of claims 8 to 10, wherein said data (D) is encrypted.

12. A method for evaluating a distance (d) between a first wireless communication circuit (12) equipping an on-board system (15) and a second wireless communication circuit (22) equipping an identifier (20), characterized in that data exchanges (D) between the first wireless communication circuit (12) and the second wireless communication circuit (22) are implemented (E10, E12) during time slots separated by an interval. predetermined time according to a communication protocol, the evaluation method comprises, after each of a plurality of said data exchanges (D), a step (E14; E16) for triggering an exchange, between the first circuit of wireless communication (12) and the second wireless communication circuit (22), at least one electromagnetic signal (R) used to evaluate said distance (d).

The method of claim 12, wherein the first wireless communication circuit (12) exchanges a plurality of electromagnetic signals (R) at different frequencies with the second wireless communication circuit (22), the method comprising a step evaluating said distance (d) based on measurements of said electromagnetic signals (R).

The method of claim 12 or 13, wherein said data (D) comprises configuration data (CONF) of said electromagnetic signals (R).

15. Method according to one of claims 12 to 14, wherein said data (D) are exchanged encrypted.