Vehicle obstacle detection and signaling system

Abstract

Vehicle Obstacle Detection and Signaling System The invention relates to a vehicle obstacle detection and signaling system, comprising: - photonic emitters on the front of the vehicle, - means for emitting a high-frequency coded light signal (s1) to the outside of the vehicle, - means for receiving a reflected, high-frequency coded light signal arriving from outside the vehicle, the receiving means being coupled to means for detecting obstacles on the vehicle, the signaling and detection system comprising a control unit supplying a first set of photonic emitters with a low-frequency voltage (PWM15) to emit a signal light, and the emitting means comprising a control unit supplying a second set of photonic emitters with a high-frequency voltage for the high-frequency coded light signal (s1). (Figure 4)

Description

Title of the invention: Vehicle obstacle detection and signaling system

[0001] The present invention relates to the fields of automotive, optics and electronics. More specifically, it relates to a vehicle signaling system.

[0002] In modern vehicles, light-emitting diode (LED) arrays are commonly used to create external lighting devices such as dipped or signal lights. These LED arrays allow for energy savings while providing vehicles with distinctive brand-specific light signatures, and are anticipated as future means of communication between vehicles or with road infrastructure, thanks to optical communication technologies such as VLC (Visible Light Communication), for example.

[0003] Indeed, the bandwidth of a conventional light-emitting diode with a side of one millimeter is approximately 5 MHz (Megahertz), and is therefore sufficient to enable light communication between vehicles or between a vehicle and road infrastructure. However, this bandwidth is not suitable for obstacle detection applications. Such an application is generally implemented optically in certain vehicles using LiDAR (Light Detection and Ranging) technology based on laser sensors that allow analysis of the reflected signal over a bandwidth on the order of several tens of Megahertz, or even several hundred Megahertz. LiDAR systems installed on vehicles are nevertheless very expensive.

[0004] The inventors have discovered, however, that such an obstacle detection application is possible by using light-emitting diodes (LEDs), by increasing their bandwidth, either through equalization techniques, or by using diodes smaller than 300 micrometers, or by combining these techniques. This application may require the use of a specific type of control unit, such as a high-speed control unit or a laser control unit. Furthermore, the LEDs used for this application are blue LEDs adapted to emit white light.

[0005] Thanks to this discovery, the inventors have made it possible to replace, in a vehicle, the costly means of LiDAR technology with specific signaling devices based on light-emitting diodes, which, in addition to regulatory signaling functions, perform an obstacle detection function. In particular, the obstacle detection function is carried out during the day by the daytime running lights, also called DRL (for the English "Day Running Lights").

[0006] The cost of this obstacle detection function is, however, not negligible, especially since, in order to detect obstacles in a blind area at the front of the vehicle, between the front left and front right optical blocks of the vehicle, light-emitting diodes present on the front of the vehicle are often used in addition to signal lights for obstacle detection to illuminate the vehicle logo or to perform display functions or even purely aesthetic ones.

[0007] The number of LEDs used for the obstacle detection function is therefore very large, requiring several high-frequency power supplies and several associated driver units. These driver units are more expensive than those typically used for simply emitting a traffic light, and they consume more energy. Furthermore, the distance between the different LEDs powered by different high-frequency modulated power supplies, for example, high-frequency modulated voltage sources, can generate interference problems between the signals emitted by these different sources.

[0008] The present invention aims to remedy at least in part the aforementioned drawbacks by providing a vehicle signaling and obstacle detection system, which reduces the costs of the obstacle detection function, and the problems of interference between the different high-frequency signals.

[0009] To this end, the invention proposes a signaling and obstacle detection system for a vehicle, comprising: - a plurality of photonic emitters distributed on one side of the vehicle, - means for emitting a high-frequency coded light signal to the outside of the vehicle, - means for receiving a reflected light signal, coded at high frequency and arriving from outside the vehicle, the receiving means comprising means for coupling to means for detecting obstacles on the vehicle, the signaling and detection system being characterized in that it includes at least one control unit capable of supplying a first part of the plurality of photonic emitters with a low-frequency modulated power supply, to emit a signal light, and in that the emission means include at least one control unit capable of supplying a second part of the plurality of photonic emitters with a high-frequency modulated power supply to form at the output of the photonic emitters of the second part, the high-frequency coded light signal.

[0010] The photonic emitters are preferably light-emitting diodes. They are powered by several power sources and several control units. These control units correspond either to a low-frequency control unit or a high-frequency control unit. Specifically, each optical unit in the vehicle has at least one dedicated power supply and control unit.

[0011] Thanks to the invention, the photonic emitters participating in a vehicle signaling function are at least partially powered by a low-frequency modulated power supply, i.e., on the order of one hundred Hertz, which is much less expensive than the high-frequency modulated power supply powering the second part of the photonic emitters, participating in the obstacle detection function. Furthermore, reducing the number of high-frequency sources allows for a reduction in interference between the high-frequency signals.

[0012] Preferably, the vehicle's front is a front face, and the signaling function is a night-time position light or a day-time position light, located at least partially on the front face. Preferably, the photonic emitters contribute to both the night-time position light and day-time position light functions; thus, the detection function can be performed day and night.

[0013] Light emitters can be considered to be located on the same face when they directly illuminate the same objects when the signaling and detection system is operating.

[0014] It is understood that the modulated power supply can be achieved by a voltage source or a current source, or any other electronic device capable of driving photonic emitters at the appropriate frequency, in particular pumping devices adapted for high-frequency control. In the present description of the invention, references to the power supply refer interchangeably to voltage and current, and references to the power supply device refer interchangeably to voltage sources and current sources.

[0015] It should be noted that in this application, "low frequency" means a frequency below 1000 Hz and can be 0 Hz for a continuous supply, while "high frequency" means a frequency above 1 MHz.

[0016] In one embodiment of the invention, the first part of the plurality of photonic emitters and the second part of the plurality of photonic emitters are capable of together forming a light distribution corresponding to a daytime or nighttime position light. In this embodiment, in order to save the energy and material costs dedicated to detection, only certain photonic emitters participating in the signaling function (i.e., those capable of forming a daytime or nighttime position light) are also sources of the high-frequency coded light signal. These emitters are located near the photonic emitters participating only in this signaling function, within the same optical unit of the vehicle.

[0017] In another embodiment, the first part of the plurality of photonic emitters is capable of forming a light distribution corresponding to a daytime or nighttime position light, and the second part of the plurality of photonic emitters is capable of performing a display or illumination function. In this other embodiment, the second part of the photonic emitters is, for example, located in a central part of the front of the vehicle.

[0018] Of course, many other configurations of the invention are conceivable. For example, only some of the photonic emitters participating in a daytime or nighttime position light function are used for detection and are supplemented, to ensure the detection function, by other photonic emitters located on a central part of the front of the vehicle, which also have a display or illumination function. Furthermore, separate groups of high-frequency emitting LEDs can be powered by high-frequency modulated power supplies of different frequencies. Similarly, several low-frequency modulated power supplies, at different frequencies, can be used to power the LEDs performing only one or more signaling functions.

[0019] In one embodiment of the signaling and detection system according to the invention, the receiving means comprise means for thresholding the intensity of the reflected light signal relative to a threshold, a default value of the threshold being determined as a function of an ambient light intensity, at the beginning of a detection period.

[0020] More specifically, the default value of the threshold is determined so as to distinguish between an excess of received photons and a situation in which the signaling and detection system emits no light. This excess of photons is due to the reception of the reflected light signal following the emission of the high-frequency coded light signal. For example, it could be a number of photons received per unit of time corresponding to an equal probability of receiving a photon from ambient light outside the vehicle or receiving a photon from the reflected light signal.

[0021] This default value is, for example, determined at the beginning of a detection period, lasting approximately 30 ms (milliseconds). This default value therefore depends on the intensity of sunlight during the day, but may also depend on the average intensity of light reflected by obstacles at night.

[0022] However, preferably, in this embodiment of the invention, the signaling and detection system according to the invention includes means for adapting the threshold during the detection period, depending on the light intensity emitted by the first part of the plurality of photonic emitters.

[0023] In particular, when the low-frequency modulated power supply is a pulse-width modulated signal, the adaptation means are capable of raising the threshold during a pulse of the low-frequency modulated power supply, and of lowering the threshold between two pulses of the low-frequency modulated power supply.

[0024] Optionally, when a third part of the plurality of photonic emitters is powered by other low-frequency voltage pulses, with a frequency different from the low-frequency voltage, to perform another signaling function, the adaptation means are capable of adjusting the threshold according to the light intensity emitted by the third part of the plurality of photonic emitters during each other voltage pulse. For example, the third part of the photonic emitters performs a flashing light function, while the first part of the photonic emitters performs a daytime running light function.

[0025] It should be noted that the first, second, and third parts of the plurality of photonic emitters can take very different forms without changing the nature of the invention. In particular, the first and second parts can take the form of LED arrays, i.e., LEDs sharing the same substrate, or take the form of "pixelated" LEDs, i.e., LEDs separated from one another. Optionally, the first part takes the form, in each optical block, of a single LED cooperating with a light guide, allowing the light emitted by the LED to propagate along the length of the guide and reflect the emitted light toward an output surface that can also cover the entire length of the guide. Finally, the different parts of the photonic emitters can be segmented in each optical block to provide an aesthetic effect.

[0026] When the low frequency voltage(s) have periods during which the threshold of the thresholding means is increased compared to the default value of the threshold, it is preferable that the patterns to be decoded in the reflected light signal be received at a constant threshold value.

[0027] To achieve this, the high-frequency coded light signal preferentially includes emission periods interspersed with time-dead periods straddling each rising or falling edge of the pulse-width modulated signal, the duration of the time-dead periods corresponding to twice a predetermined maximum time offset between sending the high-frequency coded light signal and receiving the corresponding reflected light signal.

[0028] In an alternative embodiment of the invention, the low-frequency modulated power supply is provided by a pulse-width modulated signal, and the high-frequency coded light signal is emitted only between two pulses of the modulated signal. pulse width.

[0029] This variant of the invention requires multiplying by two a detection period in order to have, over this detection period, the same amount of data to decode as in the main variant of the invention, which makes the detection process less fast.

[0030] In order to favor the time intervals during which code is sent over the same period of the low-frequency power supply signal, preferably when the control unit powers the second part of the plurality of photonic emitters, the duty cycle of the pulse-width modulated signal is between 10 and 50%, and the pulse value of the pulse-width modulated power supply signal is strictly greater than a given value, for example, 5V (volts). Indeed, to maintain the same light intensity at a lower duty cycle, the pulse value of the low-frequency modulated signal must be increased. The duty cycle is defined as the ratio between the time interval at which a modulated power supply is equal to its high value, divided by the period of this modulated voltage, which is the inverse of its modulation frequency.

[0031] Furthermore, in order to avoid unpleasant visual effects due to this low duty cycle, the frequency of the low-frequency modulated power supply is increased. For example, the frequency of the pulse-width modulated signal is greater than or equal to 100 Hz, preferably greater than or equal to 200 Hz. Indeed, above 200 Hz, the visual effects

[0032] Finally, in order to receive the patterns of the reflected signal only between two pulses of the low-frequency modulated power supply, it is necessary to take into account the time lag between the sending of the high-frequency coded light signal and the reception of the reflected light signal.

[0033] To do this, the high-frequency coded light signal is not emitted for example over a predetermined time interval after a falling edge or before a rising edge of the pulse-width modulated supply signal, the duration of the predetermined time interval corresponding to a predetermined maximum time offset between sending the high-frequency coded light signal and receiving the corresponding reflected light signal.

[0034] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given by reference to the accompanying schematic drawings on the other hand, in which:

[0035] [Fig. 1] represents a signaling and detection system according to the invention, in an embodiment of the invention, and the front face of a vehicle on which are arranged various photonic emitters and receivers of the signaling and detection system according to the invention,

[0036] [Fig.2] schematically represents the operation of an obstacle detection application implemented in the signaling and detection system of the [Fig.1],

[0037] [Fig.3] represents statistical distributions of the number of photons captured as a function of time by the reception means of the signaling and detection system of the [Fig.1],

[0038] [Fig.4] represents the evolution over time of the luminous intensity in candela (cd) of a high-frequency coded light signal during the operation of a low-frequency voltage source, the corresponding evolution over time of the low-frequency voltage delivered by this source, as well as the corresponding evolution over time of a threshold applied by thresholding means of the signaling and detection system of the [Fig.1],

[0039] [Fig. 5] represents the evolution over time of the luminous intensity of the high-frequency coded light signal during the operation of two low-frequency voltage sources, the corresponding evolution over time of the low-frequency voltages delivered by these sources, as well as the corresponding evolution over time of the threshold applied by the thresholding means of the signaling and detection system of [Fig. 1], and

[0040] [Fig.6] represents the evolution over time of the light intensity of a high-frequency coded light signal during the operation of a low-frequency voltage source, and the corresponding evolution over time of the low-frequency voltage delivered by this source, in an embodiment of the invention.

[0041] According to an embodiment of the invention shown [Fig. 1], a signaling and obstacle detection system 1 for a vehicle comprises, on a front face 20 of the vehicle, a plurality of photonic emitters. These photonic emitters are, in this embodiment of the invention, light-emitting diodes.

[0042] A first part of the photonic emitters is distributed between photonic emitters 14, 14b used respectively in a right front optical block and in a left front optical block of the vehicle.

[0043] A second part of the photonic emitters is distributed between photonic emitters 12, 12b used respectively in the front right optical block and in the front left optical block of the vehicle.

[0044] Finally, a third part of the photonic emitters includes light-emitting diodes 16 distributed over a central portion of the front face 20 to illuminate it and highlight a logo of the vehicle.

[0045] Although the first and second parts of the photonic emitters are shown disjoint in [Fig. 1], the light-emitting diodes forming the photonic emitters of the first and second parts are preferably made of These elements are interwoven within each optical unit of the vehicle to homogenize the appearance of the signal lights. Indeed, in this embodiment of the invention, the first and second parts of the photonic emitters cooperate to form a daytime running light. In other words, the sum of the light emissions from the photonic emitters in the first and second parts of each optical unit provides the light distribution required for a daytime running light.

[0046] The first, second, and third parts of the photonic emitters are powered by separate control units at different frequencies. In particular:

[0047] - the photonic emitters 14, 14b of the first part are driven respectively by control units 15, 15b, connected to low frequency voltage sources, the voltage delivered by these sources being here 100Hz;

[0048] - the photonic emitters 12, 12b of the second part are driven respectively by control units 3, 3b, connected to high-frequency voltage sources, delivering a high-frequency voltage of 50MHz, in this embodiment of the invention;

[0049] - and the photonic emitters 16 of the third part are driven by a unit of control 17 connected to a low frequency voltage source, the voltage delivered by this source being here 50Hz.

[0050] The photonic emitters 12, 12b of the second part are powered at a high frequency, because in addition to the signaling function in which they participate, they also participate in an obstacle detection function. More precisely, they are part of means for emitting a light signal (referenced in [Fig. 2]) coded at a high frequency and emitted outwards from the vehicle, these emission means being part of the signaling and detection system 1.

[0051] The signaling and detection system 1 also includes means for receiving a reflected light signal s2 (referenced [Fig.2]), coded at high frequency and arriving from outside the vehicle.

[0052] These receiving means include, in particular: - pluralities of photodiodes 32, 32b, each distributed respectively in the front right optical block and the front left optical block of the vehicle, - other photodiodes (not referenced) distributed over a central part of the front face 20 of the vehicle, - electronic control devices 13, 13b of the respective pluralities of photodiodes 32, 32b.

[0053] The receiving means include means for coupling to obstacle detection means 40 of the vehicle. The [Fig.2] described now will give a better understanding of the operation of the obstacle detection operated by the transmitting means, the receiving means and the detection means 40 of the signaling and detection system according to the invention.

[0054] In this embodiment of the invention, obstacle detection uses the photonic emitters 12, 12b of the vehicle's optical units. The photonic emitters comprise, for example, two blue LEDs 121, 122, adapted to emit white light. These LEDs 121, 122 of the emission means contribute to providing a daytime running light function.

[0055] The light-emitting diodes 121, 122 each comprise, for example, a layer of gallium-indium nitride (InGaN) on which a layer of phosphor is deposited. Thus, they are suitable for producing a light beam for a daytime running light.

[0056] Furthermore, the plurality 32 of photonic receivers in the receiving means of system 1 here include SPAD photodiodes (for "Single Photon Avalanche Diode") for increasing the reception gain, in particular the photodiodes referenced 321, 322. Of course, [Fig. 2] only shows two light-emitting diodes and two photodiodes for simplicity. Many more photodiodes are preferentially used, and the detection function can use many more diodes in each traffic light.

[0057] The light-emitting diodes 121, 122 are capable of emitting a light signal if coded at high frequency to the outside of the vehicle 2, and the plurality 32 of photodiodes is capable of receiving a corresponding reflected light signal s2, arriving from outside the vehicle 2.

[0058] In order to generate the high-frequency coded light signal, the right front optical block includes a voltage square wave source 10 and a control unit 3, connected upstream of the light-emitting diodes 121, 122. To send the light signal, the source 10 provides a square wave signal with a width 1 of approximately 10 ns (nanoseconds), the signal frequency being 50 MHz. The duty cycle of the signal is, for example, less than or equal to 50%. It depends on the light intensity required to generate, with the photonic emitters 14, a daytime running light.

[0059] To enable the transmission of this signal at such a high frequency level, the control unit 3 includes, for example, a pre-equalization stage, possibly combined with an amplifier stage. Instead of, or in addition to, the light-emitting diodes 121, 122 are chosen to be smaller than 300 micrometers so as to naturally have a cutoff frequency greater than 50 MHz.

[0060] Furthermore, control unit 3 includes, in a known manner, a so-called "bias" device "tee" allowing the injection of a DC voltage to the signal from the signal source 10, possibly amplified, before the application of the sum of this DC voltage and the square wave signal from the signal source 10, across the diodes 121, 122. The application of the DC voltage allows the diodes 121, 122 to be biased and allows the emission of the light signal si by them.

[0061] The light signal sent by diodes 121, 122 encodes a specific sequence of 1-second pulses of width 1 and a duration of 10 ns, this sequence repeating cyclically. The pulse sequence is defined so as to easily evaluate a time lag between its emission and reception as explained below. For example, it presents three consecutive pulses after two periods of zero voltage, then a zero voltage for one period, then two consecutive pulses, the encoded pattern being 00111011.

[0062] The reflection of the light signal si on an obstacle 6 gives rise to the reflected light signal s2 of sufficient light power to be captured by the photodiodes 321, 322.

[0063] The receiving means comprise, in addition to the photodiodes 321, 322, a blue light filter 8 for filtering the light from the reflected light signal s2 so as to allow only the blue component of this light to pass through, and a lens 9 for focusing this component towards the photodiodes 321, 322. The blue light emitted by the diodes 121, 122 generally has a lower luminous intensity than sunlight, but approaches it for wavelengths close to 460 nm. Modulation of the reflected signal s2 makes it possible to distinguish it from external light pollution in the decoding process of this reflected light signal s2.

[0064] More specifically, the photodiodes 321, 322 capture the blue components of the reflected light signal s2 and ambient light, for example, sunlight, and provide an electrical signal to the electronic control device 13, which amplifies it and supplies it to processing means 38 included in the receiving means. The electronic control device 13 optionally includes, in addition to an amplifier stage, a post-equalization stage. Since the photodiodes 321, 322 are SPAD photodiodes, the electrical signal they provide is equivalent to a count Nb of the photons received as a function of time t by each of the photodiodes 321, 322. Thresholding means 34 adjust the detection level of these photodiodes so as to separate, in the intensity of the light signal received by the photodiodes 321, 322, the portion of light intensity due to sunlight.This thresholding corresponds to a clipping of the counting signal Nb as a function of time t, beyond a number of photons corresponding to the light intensity of the blue component of sunlight, which gives rise to a thresholded light signal s3. Such thresholding allows for . remove the component due to sunlight from the received electrical signal. Of course, here we are referring to a thresholded light signal as an electrical or digital signal corresponding to the thresholding of the received light signal s2.

[0065] The processing means 38 comprise the photodiodes 321, 322 as well as the thresholding means 34 which can alternatively be implemented in software or analog form from an unthresholded electrical signal from the photodiodes 321, 322.

[0066] The processing means 38 cooperate with correlation means 36 of the thresholded light signal s3 with the light signal si sent by the diodes 121, 122. These correlation means 36 determine a time offset r between the thresholded light signal s3 and the light signal si sent, and transmit this time offset r to the obstacle detection means 40 of the vehicle 2.

[0067] The obstacle detection means 40 convert this time delay r into a distance relative to the obstacle 6, and thus enable the obstacle to be detected. The correlation means 36 are part of the signaling and obstacle detection system 1; they are, for example, located in the vehicle's optical units or in another part of the vehicle. They allow the receiving means to be coupled to the obstacle detection means 40. Communication between the correlation means 36 and the detection means 40, implemented via software, uses, for example, a CAN bus (Controller Area Network). The detection means 40 use, for example, dedicated memory and a computer in the vehicle.

[0068] It should be noted that the receiving means in the optical blocks process reflected light signals s2 corresponding to light signals emitted by one or the other of the optical blocks.

[0069] The threshold value S used by the thresholding means has a default value S0, shown in [Fig. 3], and is determined at the beginning of a detection period. A detection period corresponds to a period of reception of the light signal, approximately 30 ms in this embodiment of the invention, to which is added a processing, correlation, and obstacle detection time by the processing means 38, correlation means 36, and detection means 40. This detection period is therefore, for example, 40 ms and is repeated in a loop by the signaling and detection system 1.

[0070] This detection period is different from the duration of a pattern coded by the light signal si, which is on the order of 200 to 300ns (nanoseconds) and which is repeated cyclically over the duration of a detection period.

[0071] Returning to [Fig. 3] representing the statistical distribution Ds of the number of photons Nb received per unit time by the plurality 32 of photodiodes, when no photon emitter of the signaling and detection system 1 emits light, the number of photons Nb received per unit time by the plurality 32 of photodiodes corresponds to the statistical distribution Cl, while when the photonic emitters 12, 12b of the signaling and detection system 1 emit light, the number of photons Nb received per unit time by the plurality 32 of photodiodes corresponds to the statistical distribution C2.

[0072] The statistical distribution C1 therefore corresponds to the blue sunlight as received by the plurality 32 of photodiodes, while the statistical distribution C2 corresponds to the blue sunlight and the blue light of the reflected signal s2, received together by the plurality 32 of photodiodes. The statistical distribution C1 forms a Gaussian distribution whose peak is reached for a number NO of photons received per unit time, and the statistical distribution C2 forms a Gaussian distribution whose peak is reached for a number NI of photons received per unit time C2, NI being greater than NO. The statistical distributions C1 and C2 intersect at the default value S0 of the threshold, which therefore corresponds to a number of photons per unit time from which the photons received by diodes 321, 322 are more likely to come from the reflected signal s2 than from sunlight.

[0073] The default value S0 is therefore determined, at the beginning of a detection period, as a number of photons received per unit of time corresponding to an equiprobability of coming from an external ambient light (not from the vehicle) or from the reflected signal s2.

[0074] The default value S0 therefore does not take into account the emission of light by the first part of the photonic emitters 14, 14b, which are more or less colocalized with the second part of the photonic emitters 12, 12b. However, this light emitted at low frequency forms light pollution which can interfere with the reception of the reflected light signal s2.

[0075] In order to overcome this problem, in this embodiment of the invention, the signaling and detection system 1 adapts the value of the threshold S during the detection period, according to the light intensity emitted by the first part of the photonic emitters 14, 14b.

[0076] Figure 4 illustrates this adaptation of the threshold value S when the photonic emitters 14, 14b of the first part are powered by a pulse-width modulated low-frequency voltage PWM15 with a duty cycle of 50%, the frequency of this low-frequency voltage being 100 Hz. The PWM15 low-frequency voltage therefore produces voltage pulses of 5 ms on each 10 ms period, the value of a voltage pulse being 3.3 V, i.e., the PWM15 low-frequency voltage alternates between a low value of 0 V and a high value of 3.3 V.

[0077] Simultaneously with the emission of this low-frequency light by the photonic emitters 14, 14b, the light-emitting diodes 121, 122 emit the high-frequency coded light signal, repeating several coded patterns when the low voltage The PWM15 frequency is at its low value, and also when the low voltage, the PWM15 frequency is at its high value.

[0078] To better distinguish, at reception, the photons from the reflected light signal s2 coded at high frequency from the photons from the light emitted by the first part of the photonic emitters 14, 14b, the value of the threshold S changes, when the low frequency voltage PWM15 takes its high value, from the default value S0 to a threshold value S1 strictly greater than the default value S0.

[0079] The receiving means therefore have means for adapting the value of the threshold S, alternating this threshold value between its default value S0 and the threshold value SI synchronously with the low-frequency voltage PWM15. When the low-frequency voltage PWM15 is at its high value, the value of the threshold S is therefore equal to the threshold value SI, and when the low-frequency voltage PWM15 is at its low value, the value of the threshold S is equal to its default value S0.

[0080] In order not to disrupt the decoding process of the reflected light signal s2, it is preferable that the patterns to be decoded in the reflected light signal s2 be received at a constant threshold value. Therefore, when sending the coded patterns of the high-frequency coded light signal si, the time delay r between the transmission of a pattern of the light signal si and the reception of the corresponding pattern in the reflected light signal s2 must be taken into account.

[0081] To achieve this, a maximum time lag is determined, representing the duration between the transmission of a pattern of the high-frequency coded light signal si by the photonic emitters 12, and the reception of the pattern in the reflected light signal s2 corresponding to the light signal si, when the reflected light signal s2 originates from the reflection of the light signal si off an obstacle placed at a predetermined distance from the vehicle. This predetermined distance, for example, defines the detection range of the signaling and detection system 1 at the front of the vehicle; the non-detection of an obstacle beyond this predetermined distance is then considered not dangerous for driving the vehicle.

[0082] The emission of the high-frequency coded light signal then includes dead time periods TM that overlap each rising or falling edge of the low-frequency voltage PWM15, the duration of the dead times corresponding to twice this predetermined maximum time offset. More precisely, before and after each rising or falling edge of the low-frequency voltage PWM15, the high-frequency coded light signal takes a zero value for a duration equal to the predetermined maximum time offset.

[0083] In another example of use of the invention, when the photonic emitters 14, 14b of the first part emit continuous light, that is, when they are powered by a direct voltage, then the value of the threshold S changes from the value by default SO to threshold value SI as soon as the photonic emitters 14, 14b of the first part are activated, and remains at threshold value SI throughout the continuous emission of light by the photonic emitters 14, 14b of the first part.

[0084] In another use of the invention shown in [Fig. 5], the photonic emitters 14, 14b are powered by the low-frequency voltage PWM15, identical to that of [Fig. 4], simultaneously with the photonic emitters 16 of the third part being powered by a low-frequency voltage PWM17 at 50 Hz, which is also a square wave voltage with a 50% duty cycle. The low-frequency voltage PWM17 produces voltage pulses of 10 ms duration over every 20 ms period, the value of a voltage pulse being 5 V, i.e., the low-frequency voltage PWM17 alternates between a low value of 0 V and a high value of 5 V.

[0085] Simultaneously with the emission of low-frequency light by the photonic emitters 14, 14b, and 16, the light-emitting diodes 121, 122 emit the high-frequency coded light signal si, identical to that of [Fig. 4]. In particular, the light signal si has dead times TM before and after each rising edge of one of the low-frequency voltages PWM15 and PWM17.

[0086] To better distinguish, at reception, the photons from the reflected high-frequency coded light signal s2 from the photons from the light emitted by the photonic emitters 14, 14b, and 16, the value of the threshold S is adjusted according to the emission times of the low-frequency voltages PWM15 and PWM17. Thus:

[0087] - when the low-frequency voltages PWM15 and PWM17 are at their low values, the The threshold value S is equal to its default value S0.

[0088] - when the low-frequency voltages PWM15 and PWM17 are at their high values, the threshold value S is equal to a threshold value S12 strictly greater than the threshold value SI,

[0089] - when the low-frequency voltage PWM17 is at its high value and the low-frequency voltage The PWM15 frequency is at its low value, the threshold value S is equal to a threshold value S10 strictly greater than the default value S0 but less than the threshold value SI, and

[0090] - when the low-frequency voltage PWM15 is at its high value and the low-frequency voltage The PWM17 frequency is at its low value, the threshold value S is equal to the threshold value SI.

[0091] It should be noted that the increase in the value of the threshold S to take into account the emission from diodes 16 is small compared to the increase in this threshold to take into account the emission from diodes 14, 14b, because diodes 16 are much further from the photonic emitters 12, 12b than diodes 14, 14b. Indeed, the adjustment of the value of the threshold S depends on the light intensity of the sources. vehicle light to be taken into account, but also the distance of these light sources from the location of the photonic emitters 12, 12b.

[0092] Figure 6 now illustrates an alternative embodiment of the invention, in which the photonic emitters 14, 14b of the first part are powered by a low-frequency voltage PWM15c, simultaneously with the emission of high-frequency light by the photonic emitters 12, 12b of the second part. For simplicity, it is assumed here that the diodes 16 are not activated and that only the photonic emitters 14, 14b, 12, and 12b are activated.

[0093] In this embodiment, in order to eliminate any light pollution from other light sources in the vehicle, the photonic emitters 12, 12b of the second part send a high-frequency coded SiC light signal only between two voltage pulses from the low-frequency voltage PWM15c. This reduces the number of patterns to be decoded, received by the plurality 32 of photodiodes over the same period of time, compared to the main embodiment. Rather than increasing the detection period to mitigate this drawback, a duty cycle of between 10 and 50% is chosen for the pulse-width modulated low-frequency PWM15c voltage, here 20%. To compensate for the loss of brightness due to this low duty cycle, the high value of the PWM15c low-frequency voltage is chosen to be relatively high, here 5 V. To limit the visual effects due to this low duty cycle, a relatively high frequency is also chosen for the power supply of the photonic emitters 14 and 14b in the first part, which only have a signaling function; here the chosen frequency is 250 Hz.

[0094] Finally, as in the main embodiment, in order to receive the reflected light signal corresponding to the high-frequency coded SiC light signal, between two low-frequency voltage pulses, the high-frequency coded SiC light signal is not emitted over a predetermined AM time interval after a falling edge or before a rising edge of the low-frequency voltage PWM15c. This predetermined AM time interval corresponds, for example, to the predetermined maximum time offset mentioned previously in relation to [Fig. 5].

[0095] The implementation examples shown in the figures and described above implement the invention within the framework of voltage modulation achieved by voltage or current sources. Those skilled in the art will be able to adapt the examples described in the figures without any difficulty to other types of power supply devices, for example, current sources and pumped power supplies suitable for high frequencies, in particular devices employing capacitors or H-bridges, which are well known to those skilled in the art.

[0096] Of course, the invention is not limited to the examples just described, and many modifications can be made to these examples without departing from the scope of the invention. In particular, the features of different embodiments can be combined to carry out the invention, provided that these embodiments are not incompatible with each other. For example, it is possible to adapt the threshold value S to the light intensity emitted by the photonic emitters 14, 14b during the pulses of the low-frequency voltage PWM15c, similarly to the example in [Fig. 4], so as not to impose a predetermined time interval AM between the end of a pattern of the high-frequency coded sic light signal and the beginning of a rising edge of the low-frequency voltage PWM15c, or between a falling edge of the low-frequency voltage PWM15c and the beginning of a pattern of the high-frequency coded sic light signal.

Claims

Claims

1. Signaling and obstacle detection system (1) for a vehicle, comprising: - a plurality of photonic emitters (12, 12b, 14, 14b, 16) distributed over a face (20) of the vehicle, - means (10, 3, 3b, 12, 12b) for transmitting a high-frequency coded light signal (s1, s2) to the outside of the vehicle, - means (32, 32b, 13, 13b) for receiving a reflected, high-frequency coded light signal (s2) arriving from outside the vehicle, the receiving means (32, 32b, 13, 13b) comprising means for coupling to obstacle detection means (40) of the vehicle, the signaling and detection system (1) being characterized in that it comprises at least one control unit (15, 15b) capable of supplying a first part (14, 14b) of the plurality of photonic transmitters with low-frequency modulated power supply, for emitting a signal light, and in that the transmission means (10, 3, 3b, 12,12b) comprise at least one control unit (3, 3b) capable of supplying a second part (12, 12b) of the plurality of photonic emitters with a high-frequency modulated power supply to form at the output of the photonic emitters of the second part (12, 12b), the high-frequency coded light signal (si, sic).,

2. System (1) for signaling and obstacle detection according to claim 1, in which the first part (14, 14b) of the plurality of photonic emitters and the second part (12, 12b) of the plurality of photonic emitters are capable of forming together a light distribution corresponding to a daytime or nighttime position light.

3. System (1) for signaling and obstacle detection according to claim 1, in which the first part (14, 14b) of the plurality of photonic emitters is capable of forming a light distribution corresponding to a daytime or nighttime position light, and the second part of the plurality of photonic emitters is capable of performing a display or illumination function.

4. System (1) for signaling and obstacle detection according to any one of claims 1 to 3, in which the reception means (32, 32b, 13, 13b) comprise thresholding means (34) of an intensity of the reflected light signal (s2) relative to a threshold (S), a default value (S0) of the threshold (S) being determined according to an ambient light intensity, at the start of a detection period.

5. System (1) for signaling and detecting obstacles according to claim 4, comprising means for adapting the threshold (S) during the detection period, as a function of the light intensity emitted by the first part (14, 14b) of the plurality of photonic emitters.

6. System (1) for signaling and obstacle detection according to claim 5, in which the low-frequency power supply is a pulse-width modulated signal (PWM15), the adaptation means being capable of raising the threshold (S) during a pulse of the low-frequency modulated power supply signal, and of lowering the threshold (S) between two pulses of the low-frequency modulated power supply signal.

7. System (1) for signaling and obstacle detection according to claim 6, in which a third part (16) of the plurality of photonic emitters is powered by other low-frequency voltage pulses (PWM17), of a frequency different from the low-frequency voltage, to perform another signaling function, and in which the adaptation means are capable of adjusting the threshold (S) as a function of the light intensity emitted by the third part (16) of the plurality of photonic emitters, during each other voltage pulse.

8. System (1) for signaling and obstacle detection according to claim 6 or 7, in which the high-frequency coded light signal (si) comprises transmission periods interspersed with dead times (TM) temporally straddling each rising or falling edge of the pulse-width modulated signal, the duration of the dead times (TM) corresponding to twice a predetermined maximum time shift between sending the high-frequency coded light signal (si) and receiving the corresponding reflected light signal (s2).

9. A signaling and obstacle detection system (1) according to any one of claims 1 to 5, wherein the low-frequency voltage is a pulse-width modulated signal (PWM15c), and wherein the high-frequency coded light signal (sic) is emitted only between two pulses of the pulse-width modulated signal (PWM15c).

10. System (1) for signaling and obstacle detection according to claim- indication 9, wherein when the control unit (3, 3b) supplies the second part (12, 12b) of the plurality of photonic emitters, the duty cycle of the pulse width modulated signal (PWM15c) is between 10 and 50% and the value of the voltage pulses of the pulse width modulated signal (PWM15c) is strictly greater than a given value, in particular greater than 5V.

11. System (1) for signaling and obstacle detection according to claim 10, in which the frequency of the pulse width modulated signal (PWM15c) is greater than or equal to 100Hz.

12. System (1) for signaling and obstacle detection according to any one of claims 9 to 11, in which the high-frequency coded light signal (sic) is not emitted over a predetermined time interval (AM) after a falling edge or before a rising edge of the pulse-width modulated signal, the duration of the predetermined time interval (AM) corresponding to a predetermined maximum time shift between a sending of the high-frequency coded light signal (sic) and a reception of the corresponding reflected light signal.

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