Telemetry light system for a motor vehicle comprising a module for receiving a light beam

Abstract

The invention relates to a telemetry system for a motor vehicle, the system comprising a receiving module (3) that comprises a plurality of elementary acquisition modules (32), each capable of generating an elementary detection signal (Sde); and a computing unit (4) capable of detecting, in each received elementary detection signal (Sde), the presence of a sequence (Seq) of predetermined data; characterised in that, in the absence of detection of the data sequence (Seq) in a first elementary detection signal (Sde1) generated by a first elementary acquisition module (321), the computing unit (4) is arranged to generate a combination of the first elementary detection signal (Sde1) and of a second elementary detection signal (Sde2) generated by a second elementary acquisition module (322) adjacent to the first elementary acquisition module (321), and to detect the presence of the data sequence (Seq) in the combination.

Description

Description Title of the invention: Light telemetry system for a motor vehicle comprising a module for receiving a light beam

[0001] The invention relates to the field of automotive lighting and / or light signaling, to functions for detecting an object by a motor vehicle and estimating the distance separating this object from the vehicle. More specifically, the invention relates to a lighting and / or signaling system for a motor vehicle capable of implementing telemetry functions.

[0002] It is known, in the automotive field, to use a pulsed light beam emitted by a light module of a lighting system of a motor vehicle to perform a given photometric function.

[0003] Conventionally, the light source enabling the emission of this light beam is controlled by a pulse width modulated electrical signal, or PWM (from the English "Pulse Width Modulation"). The light source is thus periodically activated and deactivated by this PWM signal, so that the emitted light beam is composed of light pulses succeeding one another with a frequency high enough that the human eye can no longer distinguish them. The intensity of the emitted light beam is a function of the duty cycle of this PWM signal, so that it is possible to control it by adjusting this duty cycle and therefore to perform a photometric function.

[0004] Beyond the realization of one or more photometric functions, such as a daytime running light or dipped-beam lighting, various functions can be implemented by this type of light module. For example, the light source of the light module can be controlled so that the pulses of the emitted light beam carry a data sequence. The lighting system can thus be equipped with a reception module in order to receive the emitted light beam, after reflection on an object in the vicinity of the vehicle. A computing unit of the motor vehicle can then, after detecting the data sequence in the received light beam, determine the time of flight of the emitted light beam and therefore evaluate the distance separating the vehicle from the object.

[0005] In this way, the light beam can retain its original function, namely performing a photometric function, while allowing the lighting system to implement a telemetry function, which can be particularly advantageous, for example, for driving assistance functions or in the context of autonomous or semi-autonomous driving.

[0006] However, this type of system based on the use of a transmission module capable of both performing a photometric light function and data transmission has drawbacks. Indeed, the reception module intended to receive the light beam carrying the data, whether it is arranged in the same vehicle or in another vehicle, must include at least one photodetector to convert this light beam into an electrical signal in order to demodulate this signal and extract a data sequence from it.

[0007] Generally speaking, in order to be able to detect an object with an acceptable spatial resolution, it is necessary to use an array of photodetectors, each photodetector being intended for the detection of an object in a given angular range.

[0008] However, under certain conditions, a photodetector may see its signal-to-noise ratio significantly degraded, taking into account the sources of stray light present in the vehicle's environment, such as urban lighting, automobile lighting from passing or following vehicles, or even sunlight, and the nature of the objects present in the environment, and in particular their reflective capacity. This degradation of the signal-to-noise ratio can then reduce the accuracy of the calculation unit in estimating the distance of the target object, or even lead to false positive detections.

[0009] Furthermore, some types of photodetectors have a dead time after receiving a photon during which they are inoperative. Given the modulation frequencies of the light beams considered, this dead time has the consequence of reducing the detection resolution and the signal-to-noise ratio of the telemetry system.

[0010] In order to increase this signal-to-noise ratio and to overcome the disadvantages mentioned, it was considered to group together, in a single elementary acquisition module, several photodetectors intended together to detect an object in the same angular range. The redundancy thus introduced makes it possible in particular to continue detection in this angular range, when one of the photodetectors is in a post-detection configuration, and this despite very high brightness. However, this solution has the disadvantage of reducing the angular resolution of the system.

[0011] There is therefore a need for a lighting system for a motor vehicle, capable of performing a telemetry function, which is efficient and whose signal-to-noise ratio is optimal in all weather conditions, as well as finding an optimal compromise between the signal-to-noise ratio and the angular resolution.

[0012] The present invention is placed in this context, and aims to meet these needs.

[0013] To this end, a telemetry system for a motor vehicle has been developed comprising a reception module capable of receiving a light beam, in which the reception module comprises a plurality of elementary acquisition modules each comprising at least one photodetector capable of converting a light signal that it receives into an electrical signal, each elementary acquisition module being capable of generating an elementary detection signal as a function of the electrical signal(s) converted by the photodetector(s) of the elementary acquisition module, a calculation unit capable of receiving the elementary detection signals generated by the elementary acquisition modules and capable of detecting in each elementary detection signal received, the presence of a sequence of predetermined data.

[0014] According to the invention, in the absence of detection of said data sequence in at least one first elementary detection signal generated by a first elementary acquisition module, the calculation unit is arranged to generate a combination of said first signal elementary detection and a second elementary detection signal generated by a second elementary acquisition module adjacent to the first elementary acquisition module and to detect the presence of said predetermined data sequence in said combination.

[0015] The invention thus makes it possible to improve the signal-to-noise ratio in order to improve long-distance object detection while improving the angular resolution of said object detection. Indeed, the portion of the light beam received by an elementary acquisition module having generated an elementary detection signal corresponds to the reflection by an obstacle of a modulated light beam emitted and containing said sequence of predetermined data. This elementary acquisition module thus defines a detection pixel.

[0016] In the event of detection failure at a pixel corresponding to a single elementary acquisition module, a new detection will be attempted at a virtually larger pixel, corresponding to an aggregation of different acquisition modules. The portion of the light beam received by all of these elementary acquisition modules corresponds to the reflection of said modulated light beam by an obstacle contained in this larger pixel.

[0017] The fact that the computing unit can dynamically accumulate the detection information from several elementary acquisition modules then allows for easier separation of the signal from the noise. Thus, the detection of the object is dependent on the noise of the ambient environment, in other words, when the noise is low, the angular resolution is higher and when the noise is high, the computing unit includes more detection signals from elementary acquisition modules, reducing the angular resolution but making it possible to reduce the risk of false positives.

[0018] Advantageously, the plurality of elementary acquisition modules is arranged in a matrix. For example, all of the photodetectors can form a sensor, for example a single electronic component. For example, each photodetector, or each plurality of photodetectors, may have a width and / or a length of less than about ten micrometers, which makes it possible to obtain a reception field of the elementary acquisition module of at most 0.1° and therefore to increase the spatial resolution of the reception module.

[0019] Advantageously, the or each photodetector of each elementary acquisition module is an avalanche photodiode. This type of photodetector is also known as SPAD, from the English "Single-Photon Avalanche Diode". The set of avalanche photodiodes can thus form a silicon photomultiplier or SiPM (from the English "Silicon PhotoMultiplier"). This type of photodetector makes it possible to detect the incidence of a single photon with a significant gain, for example of the order of 106, and therefore to compensate for the degradations of the signal-to-noise ratio due to external conditions

[0020] According to an exemplary embodiment of the invention, the reception module may comprise an optical unit arranged in front of the elementary acquisition modules.

[0021] In a particular embodiment, each elementary acquisition module comprises a comparator arranged to compare the electrical signal converted by each photodetector with a given threshold value and to generate said elementary detection signal as a function of said comparison. The comparator thus forms a unit for demodulating the light beam received by the reception module, capable of extracting a data sequence, called demodulated, from an electrical signal converted by a photodetector.

[0022] Preferably, each elementary acquisition module comprises a plurality of photodetectors, the comparator being arranged to compare the electrical signal converted by each photodetector to the same given threshold value and to generate an elementary detection sub-signal as a function of said comparison. Where appropriate, the comparator is arranged to sum the elementary detection sub-signals to form the elementary detection signal.

[0023] In a particular embodiment, for each elementary detection signal that it receives, the calculation unit is arranged to estimate values ​​of a correlation function between said elementary detection signal and said sequence of predetermined data and to detect the presence of said sequence of predetermined data in said elementary detection signal from said values ​​of the correlation function.

[0024] For example, the calculation unit is arranged to estimate each value of the correlation function between said elementary detection signal and said predetermined data sequence by evaluating the cross-correlation of the elementary detection signal and said predetermined data sequence delayed by a given duration associated with said value.

[0025] In other words, each value of the correlation function is thus associated with a value of a time shift of the modulating sequence used to estimate this value of the correlation function. The calculation unit is thus arranged to identify the time shift value associated with the maximum value of the cross-correlation function.

[0026] Preferably, the calculation unit is arranged to determine the value of a peak of said correlation function, to compare said peak value with a predetermined threshold value and to detect the presence of said predetermined data sequence in said elementary detection signal as a function of said comparison. The calculation unit may, for example, conclude that said predetermined data sequence is present in said elementary detection signal only if said peak value is greater than the predetermined threshold value, and may, otherwise, generate said combination of the first and second elementary detection signals.

[0027] In a particular embodiment, the calculation unit is arranged to generate said combination of said first elementary detection signal and a second elementary detection signal generated by a second elementary acquisition module adjacent to the first elementary acquisition module by adding said first and second elementary detection signals.

[0028] Thus, the computing unit is arranged to generate a combination of detection signals, and thus determine the presence of an object if the value of the peak of the combination is greater than the predetermined threshold value.

[0029] In a preferred embodiment, the calculation unit is arranged to, in the absence of detection of said predetermined data sequence in a first combination of elementary detection signals generated by a plurality of elementary acquisition modules: a. generate a second combination of said first combination and of an elementary detection signal generated by an elementary acquisition module neighboring said plurality of elementary acquisition modules, b. detect the presence of said predetermined data sequence in said second combination.

[0030] Where appropriate, the computing unit is arranged to iterate the steps of generating a combination of elementary signals and detecting said predetermined data sequence in said combination, until said predetermined data sequence is detected in a combination of elementary signals and / or at least one predetermined stopping condition is satisfied.

[0031] Preferably, the calculation unit is arranged to generate said second combination from said first combination and from an elementary detection signal generated by an elementary acquisition module neighboring said plurality of elementary acquisition modules and located in a given direction of the first elementary acquisition module from which the first combination was generated.

[0032] In a particular embodiment, the calculation unit is arranged to generate several second combinations from the first combination and elementary detection signals generated by neighboring elementary acquisition modules of said plurality of elementary acquisition modules and located in different given directions from the first elementary acquisition module from which the first combination was generated. The generation and detection steps will thus be iterated for each of the second combinations thus generated until said predetermined data sequence is detected in a combination of elementary signals and / or at least one predetermined stopping condition is satisfied, all of the iterations initiated in said given direction from the initial elementary acquisition module being stopped in this case.

[0033] For example, it may be envisaged that the neighboring modules are the modules immediately to the left, to the right, above and below the first elementary acquisition module from which the first combination was generated. More particularly, the calculation unit may be arranged to generate a second combination using the elementary acquisition module located to the right of the first elementary acquisition module from which the first combination was generated, a second combination using the elementary acquisition module located to the left of this first elementary acquisition module, a second combination using the elementary acquisition module located at the top of this first elementary acquisition module and a second combination using the elementary acquisition module located at the bottom of this first elementary acquisition module.

[0034] In a preferred embodiment, said stopping condition is satisfied if the number of elementary acquisition modules making up said plurality of elementary acquisition modules is greater than a predetermined threshold number. It will thus be possible to limit the expansion of the combinations to a given number of elementary acquisition modules from the initial elementary acquisition module in a given direction, for example to 20 acquisition modules.

[0035] In a particular embodiment, said stopping condition is satisfied if the calculation unit has detected the presence of said predetermined data sequence in the elementary detection signal received from said neighboring elementary acquisition module.

[0036] In one embodiment of the invention, the system comprises an emission module comprising a light module capable of emitting a light beam, and a modulation unit capable of receiving a data sequence, called a modulating sequence, and arranged to modulate the light beam emitted from said modulating sequence. Said modulating sequence thus forms said predetermined data sequence that the calculation unit seeks to detect.

[0037] The light beam may for example be a pulsed beam, each pulse corresponding to one or more consecutive high values ​​of the modulating data sequence and the interval separating two consecutive pulses corresponding to one or more consecutive low values ​​of this modulating data sequence. Each pulse of the modulated light beam is emitted with a peak light power, so that the average light power of the emitted modulated light beam is thus defined by the peak light power and the duty cycle of the modulating data sequence.

[0038] The light beam received by the receiving module thus contains the reflection of the light beam by an object to be detected. Said elementary detection signal received by the computing unit is therefore formed from a data sequence, called demodulated, composed of the delayed modulating sequence and noise. Each value of the correlation function estimated by the computing unit is associated with a value of a time shift of the modulating sequence, or of the demodulated sequence, used to estimate this value of the correlation function. The correlation function between this demodulated data sequence and the modulating sequence is therefore a function of the autocorrelation of this modulating sequence.

[0039] It is thus possible to detect the presence of this modulating data sequence in the received light beam, after reflection on an object in the vehicle's environment and thus detect the presence of this object as well as estimate its distance from the vehicle.

[0040] In one embodiment of the invention, the light module is capable of emitting a light beam whose spectrum has a peak at a wavelength in the visible, in particular between 400 nm and 500 nm. Advantageously, the light module comprises a light source comprising a semiconductor generator capable of emitting an elementary light beam, in particular the spectrum of which has a peak at a wavelength in the visible, and a photoluminescent element capable of converting said elementary light beam to obtain said light beam.

[0041] The semiconductor may, for example, be a gallium nitride, or GaN, capable of emitting, by electroluminescence and in response to an electric current passing through it, rays of blue light. The photoluminescent element may, for example, be in the form of a resin comprising a cerium-doped yttrium aluminum garnet, or CE:YAG, capable of absorbing blue light and, by photoluminescence and in response to the excitation carried out by this light, emitting rays of yellow light. The photoluminescent element is arranged on the generator so that a portion of the blue light rays excites this element so that it emits, by photoluminescence, rays of yellow light. The other portion of the blue light rays passes through this element. Thus, the light source emits simultaneously, when it is electrically powered, rays of blue and yellow light, the light thus formed appearing white to the human eye.

[0042] The light source could therefore be a laser type source, a light-emitting diode, a vertical-cavity surface-emitting laser diode, also called VCSEL (from the English "Vertical-Cavity Surface-Emitting Laser") or even a superluminescent diode or SLED (from the English "Superluminescent diode").

[0043] Advantageously, the light module may comprise an optical unit arranged to project the light rays emitted by the light source to form said light beam.

[0044] Advantageously, the modulation unit is arranged to generate a pulse-width modulated control signal, to modulate said control signal from the modulating data sequence and to control the emission of said light beam by the light module from the modulated control signal. For example, the modulation unit may be arranged to convert the modulating data sequence into a modulating signal and to modulate, for example in amplitude, frequency or phase, the control signal with this modulating signal.

[0045] Where appropriate, the modulation unit may be arranged to control the light source of the light module, and in particular a power supply supplied to this light source, to modulate the light beam.

[0046] Advantageously, the calculation unit is arranged to generate a modulating data sequence, in particular of pseudo-random binary type, to transmit the modulating data sequence to the modulation unit of the transmission module for the transmission of a light beam modulated by the transmission module.

[0047] A pseudo-random binary sequence, or PRBS, is a data sequence composed of high values, namely "1s", and of low values, namely "0". This type of sequence has particularly interesting properties. Indeed, its autocorrelation function is maximum for a zero time lag, that is to say when the sequence is compared to itself, and has a value significantly lower than this maximum for all other time lags, that is to say when the sequence is compared to time-shifted versions of itself.

[0048] Furthermore, the cross-correlation function between two pseudo-random binary sequences is significantly smaller than the maximum of the autocorrelation functions of these sequences. Finally, this type of sequence is generally generated using a linear feedback shift register, or LFSR, which produces a periodic recurring sequence whose pattern is a pseudo-random binary sequence.

[0049] Given the autocorrelation properties of pseudo-random binary sequences, the correlation function thus estimated will be maximum for the time shift value corresponding to the time of flight of the modulated light beam emitted, reflected then received, even in the event of significant noise.

[0050] Therefore, the computing unit can identify this time shift value associated with the maximum value of the correlation function with significant precision and deduce the distance separating the object on which the beam was reflected and the motor vehicle.

[0051] Furthermore, given the cross-correlation properties, it thus appears unlikely that the reception of a modulated light beam emitted by an equivalent system of another motor vehicle would lead to the detection of a false positive.

[0052] Finally, we understand that the detection is carried out not on a single pulse but on a complete data sequence, so that the signal-to-noise ratio of the system is improved.

[0053] Advantageously, the emission module is arranged so that the light beam participates, totally or partially, in the realization of a predetermined regulatory photometric function. It could for example be a daytime running light or DRL (from the English "Daytime Running Lamp"), which has the advantage of being emitted in a wide field with a low intensity.

[0054] Advantageously, the transmission module is arranged in a front headlight of the motor vehicle. Preferably, the reception module and the transmission module are arranged in the same front headlight of the vehicle.

[0055] The invention also relates to a telemetry method implemented by a system according to the invention.

[0056] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

[0057] In addition, various other features of the invention will be apparent from the accompanying description. carried out with reference to the drawings which illustrate non-limiting forms of embodiment of the invention and where:

[0058] [Fig.l] represents, schematically and partially, a view of a telemetry system of a motor vehicle according to an exemplary embodiment of the invention.

[0059] [Fig.2] schematically represents an example of operation of the system in the absence of detection of the predetermined data sequence.

[0060] [Fig.3] represents, schematically and partially, an example of operation of the system of [Fig.l] during the implementation of a telemetry method.

[0061] It should be noted that in these figures the structural and / or functional elements common to the different variants may have the same references.

[0062] Of course, various other modifications may be made to the invention within the scope of the appended claims.

[0063] Referring to [Fig. 1], the present invention is a telemetry system 1 of a vehicle comprising a transmitting module 2, a receiving module 3, and a computing unit 4.

[0064] The emission module 2 comprises a light module 21 capable of emitting a first light beam Fl, and a modulation unit 22 capable of receiving a modulating data sequence Seq and arranged to modulate the light beam Fl emitted from said modulating sequence Seq.

[0065] The first emission module 2 is for example arranged in a headlight of the motor vehicle.

[0066] The light module 21 is arranged so that the light beam Fl that it emits has an electromagnetic spectrum of which at least a portion is located in the visible spectrum. Preferably, the spectrum of this light beam Fl has an intensity peak, or line, in the blue at 450 nm. It will be noted that it is possible for the spectrum to have other intensity peaks, in the visible and / or in the infrared.

[0067] To the extent that the light beam Fl is composed, partially or totally, of white light, it is possible to use this light beam to participate, partially or totally, in the realization of a predetermined photometric function, in particular regulatory. In this case, the light module 21 may comprise an optical unit arranged to shape this light beam Fl so that its photometric distribution satisfies the requirements of said function. For example, it may be provided that the light beam Fl participates in the realization of a function of the daytime running light, or DRL, type.

[0068] In addition to this photometric function, the light beam Fl allows the system 1 to perform functions of detecting and evaluating the position of an obstacle on the road and / or communicating with another vehicle or with road infrastructure.

[0069] For these purposes, the modulation unit 22 is arranged to modulate the light beam Fl emitted by the light module 21, from the sequence of modulating data Seq that it receives, for example by controlling the electrical power supplied to the light source of the light module.

[0070] It will thus be possible to provide that the modulation unit 22 comprises a generator of a pulse width modulated control signal. This control signal makes it possible to control a switching power supply (not shown) of the light source of the light module 21. Conventionally, the duty cycle of this control signal, set by the modulation unit 22, thus makes it possible to control the average electrical power supplied to the light source, and therefore to control the light intensity of the light beam F1, so as to satisfy the requirements of the photometric function that it performs.

[0071] In the example described, the modulation unit 22 is arranged to convert the data sequence Seq into a modulating signal and to modulate the initial control signal using this modulating signal. It will be noted that several types of modulation can be used indifferently within the framework of the present invention, and in particular an on-off keying modulation (OOK), a pulse code modulation (PGM), a pulse amplitude modulation (PAM), a pulse width modulation (PWM) or a pulse position modulation (PPM).

[0072] The light beam Fl thus emitted is composed of a train of light pulses succeeding one another with a sufficiently high frequency, for example greater than 30 MHz, in particular between 50 MHz and 100 MHz, so that the human eye can no longer distinguish them. Furthermore, the amplitude, width and / or position of each pulse with respect to the period allows the light beam Fl to carry the data sequence Seq.

[0073] If an object is present in the environment of the motor vehicle, it can reflect this light beam Fl towards the receiving module 3, which thus receives a light beam F2.

[0074] In connection with [Fig. 2] representing an exemplary embodiment of a reception module 3, this reception module 3 comprises a plurality of elementary acquisition modules 32i,j, each comprising several photodetectors 32a capable of converting a light signal that it receives into an electrical signal. Each elementary acquisition module 32i,j further comprises a demodulation unit 34, comprising a comparator arranged to compare the electrical signal converted by each photodetector 32a of the module 32i,j to the same given threshold value. The demodulation unit 34 is thus arranged to generate, from each of the comparisons of the electrical signals from the photodetectors 32a, an elementary detection sub-signal, and to sum the elementary detection sub-signals thus generated to generate an elementary detection signal Sdei,j, which therefore forms a data sequence, called demodulated.

[0075] The photodetectors 32a are identical and are each formed by an avalanche photodiode of a silicon photomultiplier. It should be noted that the dimensions of the photodetectors are of the order of a micrometer. The assembly thus forms a sensor whose resolution spatial reception is of the order of 1°, or even 0.1°, and whose detection capacities, due to the use of avalanche photodiodes, are particularly significant, even in the event of degraded acquisition conditions.

[0076] Each of the photodetectors 32a of the same elementary acquisition module 32i,j can thus convert the portion of the light beam F2 that it receives into an electrical signal that it transmits to the demodulation unit 34, which can then extract a data sequence SdeiJ to transmit it to the calculation unit 4.

[0077] As shown in [Fig. 2], the elementary acquisition modules 32i,j are arranged in a matrix fashion, on N rows and M columns.

[0078] In the example described, the receiving module 3 is arranged in the headlight of the motor vehicle, next to the transmitting module 2.

[0079] The computing unit 4 is capable of receiving the elementary detection signals SdeiJ generated by the elementary acquisition modules 32i,j and capable of detecting in each elementary detection signal SdeiJ received, the presence of the modulating data sequence Seq.

[0080] For these purposes, the calculation unit 4 is thus arranged to estimate values ​​of a correlation function Fcorr between each received elementary detection signal SdeiJ and said modulating data sequence Seq, and to detect in this elementary detection signal SdeiJ, the presence of the modulating data sequence Seq from these values ​​of the correlation function Fcorr. In the event of detection, it can then determine a time of flight T separating the emission of said first emitted modulated light beam Fl from the reception of said received light beam F2.

[0081] The computing unit 4 can thus perform functions of detecting and evaluating the position of an object on the road, as will be described in connection with [Fig. 3] which represents a telemetry method implemented by the lighting system 1.

[0082] In a first step E1, the calculation unit 4 generates, periodically, a modulating data sequence Seq, for example of binary type, composed of “0” and “1”, pseudo random and of maximum size, also called M-sequence, having a duty cycle of 50%.

[0083] The computing unit 4 transmits the modulating data sequence Seq to the modulation unit 22 of the transmission module 2 for the simultaneous transmission of the light beam Fl by the transmission module 2.

[0084] In a second step E2, the modulation unit 22 modulates the light beams Fl emitted by the light module 21 from this data sequence Seq. Thus, each modulation unit 22 converts the data sequence Seq into a modulating signal and modulates the initial control signal using this modulating signal.

[0085] It will be noted that in the example described, each light pulse of the light beam Fl emitted by the light module 21 corresponds to a bit of value “1” of the modulating sequence Seq. The average power of a portion of the light beam Fl containing the sequence Seq is thus defined by the number of bits of value “1” of this sequence Seq at with regard to the total number of bits in this sequence, by the duration of the pulses and by the peak power of these pulses.

[0086] The light beam Fl is thus emitted until it reaches an object O, located in the vehicle's environment, which reflects it towards the reception module 3.

[0087] Depending on the angular position of the object O, the light beam F2 received by the reception module 3 is thus concentrated on one of the elementary acquisition modules 32i,j.

[0088] When the sunlight conditions in the vicinity of the vehicle are particularly strong, sunlight is thus added to the light beam F2 received by the receiving module 3. The light beam F2 received by the receiving module 3 is thus composed of a part of the light beam Fl reflected by the object O and of noise, for example generated by sources of stray light such as urban lighting, automobile lighting, or even the sun.

[0089] In a third step E3, each of the elementary acquisition modules 32 thus extracts, using its demodulation unit 34, an elementary detection signal SdeiJ which it transmits to the calculation unit 4.

[0090] For each elementary detection signal SdeiJ that it receives, the calculation unit 4 estimates, in a fourth step E4, values ​​of a correlation function Fcorr between the modulating sequence Seq and this elementary detection signal Sdei.

[0091] The calculation unit 4 thus evaluates, for a plurality of time shift values, the value of the cross-correlation, by means of a cyclic convolution product, between each elementary detection signal SdeiJ and the modulating sequence Seq delayed according to each of the time shift values.

[0092] Taking into account the autocorrelation and cross-correlation properties of the modulating sequence, the correlation function Fcorr will thus be maximum for a time shift value corresponding to the time of flight of the light beam Fl, separating the instant when it is emitted by the emission module 2 and the instant when it is received by an elementary acquisition module 32i,j of the reception module 3, the modulating sequence Seq delayed by this value thus corresponding substantially to the elementary detection signal SdeiJ, apart from noise.

[0093] In a fifth step E5, the calculation unit 4 identifies the maximum value Fcorr_max of each correlation function Fcorr associated with each elementary acquisition module 32i,j and compares it to a threshold value Vs.

[0094] In the case where the maximum value of a correlation function Fcorr is greater than the threshold value Vs, the modulating sequence Seq is considered to be detected by the calculation unit 4 in the elementary detection signal SdeiJ from the elementary acquisition module 32i,j associated with this correlation function Fcorr. An object O is therefore detected in the angular range, or the pixel, monitored by this elementary acquisition module 32i,j and the calculation unit 4 can then estimate, in a sixth step E6, the value T of the time of flight of the light beam Fl between the object O and the vehicle, associated with this maximum value, as well than the distance d separating object 0 from the vehicle.

[0095] On the other hand, in the case where the maximum value of a correlation function Fcorr is lower than the threshold value Vs, that is to say in the absence of detection of said data sequence Seq in the elementary detection signal SdeiJ generated by an elementary acquisition module 32i,j, the calculation unit 4 generates, in a seventh step E7, combinations Csde of this elementary detection signal SdeiJ and of each elementary detection signal Sdei-l,j, Sdei+l,j, Sdei,j-1 and Sdei,j+1 generated by the elementary acquisition modules 32i-l,j, 32i+l,j, 32i,jl and 32i,j+l located immediately to the right, to the left, at the top and at the bottom of the elementary acquisition module 32i,j.

[0096] For each of the elementary detection signals Sdei'J' generated by the elementary acquisition module neighboring the module 32i,j, the combination Csde is carried out by adding the signals SdeiJ and Sdei'J'.

[0097] Steps E4 of estimating the values ​​of the correlation function Fcorr and E5 of searching for the maximum value Fcorr_max with comparison of this maximum value to the threshold value Vs are repeated with the sequences Csde resulting from these combinations.

[0098] Again, in the absence of detection of said data sequence Seq in the different sequences Csde resulting from these combinations, the calculation unit 4 generates, in the seventh step E7, a new sequence Csde from the previous sequence Csde, obtained using the neighboring module in a direction given to the initial module 32i,j, and the elementary detection signal Sdei'J' generated by the following elementary acquisition module in this given direction.

[0099] The calculation unit 4 thus iterates the steps E7, E4 and E6, until said predetermined data sequence Seq is detected, a combination Csde of elementary signals and / or until at least one predetermined stopping condition is satisfied.

[0100] The reiteration of steps E7, E4 and E6 for a given direction is notably interrupted when the elementary detection signal Sdei'J' generated by the following elementary acquisition module in this given direction itself allows a detection of the modulating data sequence Seq in this signal or in another combination Csde originating from this signal or using this signal. It is thus considered that this following module defines or is part of another pixel in which another object has been detected.

[0101] The repetition of steps E7, E4 and E6 for a given direction is also interrupted when the number of elementary acquisition modules, whose elementary detection signals Sdei'J' compose the combination Csde, exceeds a given threshold value, for example 20. It is then considered that there is no object to be detected at the level of a pixel defined by these elementary acquisition modules or that the compromise between signal-to-noise ratio and angular resolution is no longer satisfactory.

[0102] The foregoing description clearly explains how the invention achieves the objectives it sets for itself, namely providing a lighting system for a motor vehicle, capable of performing both a given regulatory photometric function and a telemetry function, and enabling an optimal compromise to be achieved between the signal-to-noise ratio and the angular resolution. These objectives are achieved in particular using on-the-fly adaptation of the size of an elementary angular detection range, by aggregating the detection signals from the elementary acquisition modules of the reception module when these signals alone do not allow the detection of an object.

[0103] In any event, the invention cannot be limited to the embodiments specifically described in this document, and extends in particular to any equivalent means and to any technically effective combination of these means. In particular, other configurations of the emission modules may be provided, and in particular an emission module using other types of light source than those described, such as a laser diode, a VCSEL or a SLED or an RGB diode. It may also be possible to provide other photometric functions than that described, and in particular lighting functions of the dipped beam type or signaling functions of the position light or direction indicator type.

Claims

Claims

1. Telemetry system (1) of a motor vehicle comprising: A reception module (3) capable of receiving a light beam (F2), in which the reception module (3) comprises a plurality of elementary acquisition modules (32) each comprising at least one photodetector (32a) capable of converting a light signal that it receives into an electrical signal (Sel), each elementary acquisition module (32) being capable of generating an elementary detection signal (Sde) as a function of the electrical signal(s) (Sel) converted by the photodetector(s) (32a) of the elementary acquisition module (32); A calculation unit (4) capable of receiving the elementary detection signals (Sde) generated by the elementary acquisition modules (32) and capable of detecting in each elementary detection signal (Sde) received, the presence of a sequence of predetermined data (Seq); Characterized in that in the absence of detection of said data sequence (Seq) in at least a first elementary detection signal (Sdel) generated by a first elementary acquisition module (321), the calculation unit (4) is arranged to generate a combination of said first elementary detection signal (Sdel) and a second elementary detection signal (Sde2) generated by a second elementary acquisition module (322) adjacent to the first elementary acquisition module (321) and to detect the presence of said predetermined data sequence (Seq) in said combination.

2. Telemetry system (1) according to claim 1, characterized in that each elementary acquisition module (32) comprises a comparator (34) arranged to compare the electrical signal (Sel) converted by each photodetector (32a) with a given threshold value (Vs) and to generate said elementary detection signal (Sde) as a function of said comparison.

3. Telemetry system (1) according to the preceding claim, characterized in that each elementary acquisition module (32) comprises a plurality of photodetectors (32a), in which the comparator (34) is arranged to compare the electrical signal (Sel) converted by each photodetector (32a) with the same given threshold value (Vs) and to generate an elementary detection sub-signal as a function of said comparison and in which the comparator (34) is arranged to sum the elementary detection sub-signals to form the elementary detection signal (Sde).

4. Telemetry system (1) according to one of the preceding claims, characterized in that, for each elementary detection signal (Sde) that it receives, the calculation unit (4) is arranged to estimate values ​​of a correlation function (Fcorr) between said elementary detection signal (Sel) and said predetermined data sequence (Seq) and to detect the presence of said predetermined data sequence (Seq) in said elementary detection signal (Sde) from said values ​​of the correlation function (Fcorr).

5. Telemetry system (1) according to the preceding claim, characterized in that the calculation unit (4) is arranged to determine the value of a peak (P) of said correlation function (Fcorr), to compare said value of the peak (P) with a predetermined threshold value (Vs) and to detect the presence of said predetermined data sequence (Seq) in said elementary detection signal (Sde) as a function of said comparison.

6. Telemetry system (1) according to one of the preceding claims, characterized in that the calculation unit (4) is arranged to generate said combination of said first elementary detection signal (Sdel) and a second elementary detection signal (Sde2) generated by a second elementary acquisition module (322) adjacent to the first elementary acquisition module (321) by adding said first and second elementary detection signals (Sdel, Sde2).

7. Telemetry system (1) according to one of the preceding claims, characterized in that the calculation unit (4) is arranged to, in the absence of detection of said predetermined data sequence (Seq) in a first combination of elementary detection signals (Csdel) generated by a plurality of elementary acquisition modules (32): generate a second combination (Csde2) of said first combination (Csdel) and of an elementary detection signal (Sde) generated by an elementary acquisition module (32) adjacent to said plurality of elementary acquisition modules (321, 322); detect the presence of said predetermined data sequence (Seq) in said second combination (Csde2);the calculation unit (4) being arranged to iterate the steps of generating a combination of elementary signals (Csde) and of detecting said predetermined data sequence (Seq) in said combination (Csde), until said predetermined data sequence (Seq) is detected in a combination of elementary signals and / or at least one predetermined stopping condition is satisfied.;

8. Telemetry system (1) according to the preceding claim, characterized in that the calculation unit (4) is arranged to generate said second combination (Csde2) from said first combination (Csdel) and an elementary detection signal (Sde) generated by an elementary acquisition module (32) adjacent to said plurality of elementary acquisition modules (321, 322) and located in a given direction of the first elementary acquisition module (321) from which the first combination was generated (Csdel).

9. Telemetry system (1) according to the preceding claim, characterized in that said stopping condition is satisfied if the number of elementary acquisition modules (32) making up said plurality of elementary acquisition modules is greater than a predetermined threshold number.

10. Telemetry system (1) according to the preceding claim, characterized in that said stopping condition is satisfied if the calculation unit (4) has detected the presence of said predetermined data sequence (Seq) in the elementary detection signal (Sde) received from said neighboring elementary acquisition module.

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