FR2893172A1 - Motor vehicle e.g. truck, driving assistance system, has light emitting device positioned on target vehicle, and receiving device with two reception units tuned at respective frequencies of light signal emitted by emitting device - Google Patents

Abstract

The system has a light emitting device (EV) positioned on a target vehicle (VC), and a receiving device placed in front of an assisted vehicle (VA) for detecting a light signal emitted by the device (EV). The emitting device has pulsed light sources having two levels of modulation, and the receiving device comprises two reception units tuned at respective frequencies of the signal emitted by the emitting device. The sources are arranged along a determined geometric pattern according to the type of an indexed target and according to the position of the sources on the target vehicle. An independent claim is also included for a method for assisting in driving of a motor vehicle.

Description

Assistance system for driving a motor vehicle by detection

of the environment

  The present invention relates to an on-board driving assistance system in a motor vehicle for the detection of the environment, said embedded system comprising a receiver device for detecting a signal emitted by a light emitting device on board a target to detect, in order to know in real time information on its position and its relative speed with respect to obstacles in front of him such as other vehicles, as well as on the possible trajectory of these other vehicles. The information must be known with high reliability, accuracy and resolution. The invention also relates to a method of assisting the driving of a motor vehicle for the detection of the environment using such a receiver device.

  There are currently systems that use RADAR, or LIDAR, or video technologies, separately or in combination, but which do not allow for innovative driver assistance services such as Stop and Go or the maintenance of the safety distance, or active safety such as assistance with braking or obstacle avoidance, or even passive safety such as pre-crash of different levels in frontal, side and rear impact, and that for all environments and contexts specific to driving, that is to say, urban, road, highway

  . With regard to RADAR-based environmental detection systems, they have the drawback of not correctly detecting a stopped obstacle, in particular a vehicle, from having a reduced aperture wave field with an antenna. size compatible with vehicle integration and does not have high reliability when the environment analyzed becomes dense, especially in urban areas. In addition, a radar measures distances and radial velocities over a range of determined measurements, so that current ACC RADARs designed to operate over distances of several tens of meters do not perform well when the inter-vehicle distance drops to a few meters, nor can they measure the relative speed of vehicles coming in opposite directions. The lateral component of the position of the vehicles is not precise and that of the inter-vehicle speed is currently inaccessible, as well as the size and the geometry of the detected object ... DTD: Concerning the detection systems of the based on LIDARs, whether with multiple fixed or scanning beams, the infrared energy they produce is only reflected well on a few specific vehicle surfaces of relatively small dimensions, such as retro-reflectors or plate registration, and easily soiled while driving in rainy or foggy weather. In addition, their range is limited because, on the one hand, the power level emitted must not exceed a threshold that is both technical and safe for the eyes of road users and, on the other hand, the power received is generally inversely proportional to the the power four of the distance. A current solution to improve the LIDAR signal-to-noise ratio is to limit the beam emission angle, which therefore limits the vertical area of the space being explored, which can result in momentary loss of targets due to movement. roll of the transmitting vehicle and / or the target vehicle. Fixed multi-beam LIDAR systems provide longitudinal and non-lateral relative distance information, and do not provide accurate information on the size and geometry of the detected object. Scanned LIDAR systems provide information on the longitudinal and lateral components of the distance to the target, but its acquisition is slow, as well as the speed obtained by derivation. With regard to environmental detection systems based on the processing of video images on open scenes, that is, real-world scenes whose infinite variability can not be described by algorithms, we do not can guarantee the reliability of the algorithms that perform the assembly of the elementary components of the image that are extracted, such as points, segments, curves, homogeneous regions according to given criteria, to conclude on the nature of the detected object. Another disadvantage of video systems is that they require a sufficient level of contrast between the different objects of the image to be detected, which is not always guaranteed by the combination of the spectral and geometric characteristics of the natural and and the optical and geometrical properties of the different objects of a road scene.

  These three types of detection systems can be combined, such as in US Pat. No. 6,370,471 to Robert BOSCH GmbH, which describes a stop and go assistance assistance strategy in a stopper, with tracking of the line. median white, thanks to the combination of an ACC radar or short range with a video camera.

  There are also detection solutions based on communication between vehicles, with exchange of information on the relative position and speed, but which necessarily require the use of a GPS (Global Positioning System) to deliver this information with a sufficient accuracy. Finally, there are solutions based on the communication between vehicles and infrastructures, as described in the European Patent EP 0 561 353 in the name of ROCKWELL INTERNATIONAL CORPORATION, which relates to the exchange of information between vehicles by optical communication in the near infrared , with relay and transmission of information by the infrastructure. Such a solution requires on the one hand, large investments for the construction and maintenance of these infrastructures so that they will not be installed on the entire road network, and on the other hand, to define common standards for all the countries concerned. It can thus be seen that the problems not solved by the current systems are essentially due to the limits of detection and perception of the sensors used.

  The purpose of the invention is to overcome these drawbacks by proposing an on-board driving assistance system in a motor vehicle for the detection of the environment, said embedded system comprising a receiver device for the detection of a signal emitted by a light emitting device embedded on a target to be detected, characterized in that said receiving device comprises a first and a second receiving unit respectively allocated to a first and a second frequency of said distinct light signal emitted by said transmitting device. According to the characteristics of the invention: the two units are communicating with each other, the first unit being informed of the arrival of the first frequency by the detection of the second frequency by the second unit; the second frequency is higher than the first frequency, preferably 100 to 10000 higher; the second received signal with the second frequency occurs within the first received signal at the first frequency; the first unit of the receiving device is a video unit and the second unit of the receiving device is a telecom unit, the telecom unit being able to warn the video unit of the arrival of the first signal; the first unit of the receiver device comprises a video camera sensitive to visible and / or near infrared radiation, the image acquisition frequency of which is greater than the transmission frequency of the pulsed sources carried by the target, said camera being associated an image processing means for delivering the optical information produced by the target, and said acquired image processing means performs a processing which comprises a subtraction of consecutive images, acquired in a short time interval and in particular included between 1 millisecond and 25 milliseconds, for delivering the new optical information between two consecutive images received by the first unit of the receiving device; the acquired image processing means calculate, from the optical information received from the detected target, at least the distance between the assisted vehicle and the detected target or their relative speeds, or predict the relative trajectory between them; the second unit of the receiver device comprises an optronic component whose bandwidth makes it possible to acquire the second optical signal modulated at a telecommunication frequency, said optronic component comprising for example a photodetector, preferably a thermal photodetector or a quantum photodetector. Advantageously, this system is used in combination with a starting system and automatic shutdown of said assisted vehicle. The invention also relates to a method of operating the system comprising such a receiver device whose main steps are as follows: (a) reception of pulses received with a telecommunication frequency by a telecom unit of the receiver device; and (b) then triggering the acquisition of the pulses at a transmission frequency by a video unit, said triggering being generated by receiving pulses received with said telecommunication frequency. Moreover, according to this method, subtracted consecutive video images, to deliver the new optical information between two consecutive images received by said video unit. Finally, according to this method, it controls a starting device and automatic shutdown of said vehicle with the embedded system.

  Other characteristics and advantages of the invention will appear on reading the detailed description of several exemplary embodiments, illustrated by the following figures which are: FIG. 1a: three examples of patterns of pulsed light sources according to the invention, positioned on a vehicle; - Figure 2: an example of an overview of the driving assistance system according to the invention; - Figure 3a: an example of a road scene in front of an assisted vehicle; FIGS. 3b and 3: the N and N + 1 images of the road scene acquired by the video camera of the detection device according to the invention; FIG. 3d: the image obtained by difference between the images N and N + 1; FIG. 4a: the emission timing diagram of the pulsed light sources of a target, according to the invention; FIG. 4b: the detail of the chronogram of the emission of the light signal for the communication between the transmitter of the vehicle to be detected and the telecom unit of reception of the assisted vehicle, FIG. 4 and FIG. 4e: the chronogram of the transmitting the pulsed light signal and acquiring the images in the case of synchronization, respectively without synchronization, between transmission and acquisition; FIG. 4d and FIG. 4f: the result of the subtraction of images taken two by two consecutive, in the case of synchronization, respectively without synchronization, according to the system of the invention; - Figure 5: the operating steps of the transmitter device with the receiver device according to the invention; FIG. 6: the steps of the stop and go stopper method, using an assistance system according to the invention.

  The driver assistance system embedded in a motor vehicle for the detection of the environment, according to the invention, comprises a receiver device for detecting a light emitting device embedded on a target to be detected. The transmitting device produces an optical signal having a pulsed light source with two modulation levels. The modulation can be amplitude or frequency. Indeed, amplitude modulation is a special case of modulation that will be applied to the video portion of the signal explained later. The type of modulation on the telecommunication portion of the signal is however open (amplitude or frequency). According to our invention, the first modulation level is emitted with a determined fixed frequency Fe, according to a determined periodic sequence and a radiation in the visible and / or infrared range, and makes it possible to cooperate with a first unit 12 of the receiver device 10. This transmission frequency is of the order of a few tens of Hertz. Moreover, the second modulation level is emitted with a second telecommunication frequency Fooms, from 100 to 10,000 times higher than Fe, and occurs inside the light pulses of the first modulation level and makes it possible to cooperate with a second unit 14 of the receiver device 10 as illustrated in FIG. 4b. In particular, the transmitting device may comprise several pulsed elementary light sources, arranged in a geometric pattern established according to the type of target listed and according to their position on the target. Thus, for a given target vehicle the sources must emit light energy simultaneously.

  These light sources are either existing sources, already mounted on the target vehicle to be detected, such as traffic lights, codes, headlights equipping the motor vehicles, new sources specially added, or a combination of these two types of sources if you transmit the same sequence at the same frequency. The only restriction on these light sources is that they accept dual modulation at frequencies Fe and Fooms. When the rear lamps of the vehicle consist of a light-emitting diode assembly, it is easy to incorporate an LED pattern, the management electronics of which must be equipped with a module for detecting the malfunctions of the light sources. In the case of detection of such a malfunction, the driver of the vehicle must be informed, visually for example. The integration of patterns from multiple LEDs should be done in a way that minimizes the exposure of LED optics to rain and splashing from other vehicles on wet roads. In the case of sources placed on motor vehicles, which will be targets for assisted vehicles, these additional sources may be located inside existing optics, as well as externally, on the bodywork or at the edge of the roof, and can preferentially emit a near-infrared signal. These are, for example, light-emitting diodes or laser diodes. In the case of several emitting sources forming a geometric pattern, the latter may be characteristic of the target itself, a truck or a particular vehicle, for example, different according to its positioning on the target, at the front or rear or on the wings of a vehicle. These sources may even have a sub-pattern to better characterize the vehicle, by its range of mass, stiffness. Figure 1a is an example of patterns, M ,, M2 and M3 respectively, light sources, different depending on whether they are positioned on a vehicle at the front, rear or side. All the light sources of a given target vehicle must emit the same simultaneous radiation with a double modulation of frequencies Fe and Fooms, the intensity of which varies according to a periodic function of time with a frequency and a duration of emission determined according to the applications and technological constraints, and identical for reasons of simplification and robustness of the system. The emission frequency Fe may be superimposed on a lower frequency light signal or replace an initially continuous light signal since, above about 25 Hz, the human eye no longer detects the oscillations of the signal and perceives a continuous signal, this in case the transmitted optical signal is in the visible spectral band. Thus, the method of assisting the driving of a motor vehicle for the detection of the environment comprising such a transmitting device for the emission of a light signal is characterized in that it comprises the following steps: a) pulse emission with a telecommunication frequency Fooms; and (b) pulses emitting with an emission frequency Fe. The pulses of the telecommunication frequency occurring in the pulses of the transmission frequency. The receiver device 10, embedded on the vehicle is composed of two reception units which are distinct and which communicate with each other. Indeed, the first unit 12 is a video optronic unit tuned to the transmit frequency Fe of the transmitting device and the second unit 14 is a telecontrol optronic unit tuned to the telecommunication frequency Fooms. The video optronic unit 12 is composed of a video camera sensitive to visible and / or near infrared radiation, the image acquisition frequency Fa of which is greater than the emission frequency Fe of the pulsed sources carried by the target. The camera forms, with a sufficient signal-to-noise ratio, a two-dimensional image of the transmitting sources, which must be detected and localized with the precision required by the application concerned and up to the desired distances, thanks to the sensitivity and the resolution from the camera.

  The camera is associated with image processing means for delivering the optical information produced by the carrier target of the transmitting sources. The processing means use an algorithm based on the differences of images acquired by the camera at a frequency Fa which is greater than the emission frequency Fe of the light signals produced by the obstacles to be detected. The processing means subtract consecutive images acquired in a relatively short period of time to eliminate the complex and useless information of the scene seen by the camera to keep only the new information between the N and N + images. 1 for example, that is to say the optical information actually produced by the light sources of the target. Of course, it is quite possible to use the results of existing image processing to enrich the information or to make the result of the image detection even more reliable. For example, if the application uses an image processing that makes it possible to extract the contours of a vehicle, if one superimposes in this contour image, the image of the optical information actually produced by the light sources of the target, the combination of these two types of images will further improve the detection and identification of the target vehicle. FIG. 2 is an example of an overview of the driver assistance system comprising a transmitter device Ev positioned on a target vehicle Vc and a receiver device 10 placed at the front of the assisted vehicle VA, at the top of the screen. for example, at the level of the foot of the central rearview mirror or at the level of the cap on the dashboard, facing the driver. FIG. 3a is an example of a road scene occurring in front of an assisted vehicle, and comprising targets equipped with pulsed light sources Lp according to the invention. These are, for example, Vc vehicles. FIG. 3b shows the image N acquired by the video camera of the detection device mounted on the assisted vehicle. The light sources Lp active during the acquisition of this image N are blackened unlike those that are extinct. In FIG. 3, representing the next image N + 1 acquired, the previously active sources Lp are off and those previously off are on. FIG. 3d is the image obtained by difference between these two consecutive images N and N + 1, that is to say the new information between these two images, namely the pulsed light sources Lp equipping targets, without the information complex of the existing scene on these two images. FIG. 4a is the emission timing diagram of the pulsed light sources of a target. The signal is periodic, of emission frequency Fe, of determined duration of emission De and thus of duration of silence DS determined. FIG. 4c is the timing diagram of the emission of the pulsed light signal Se and the acquisition of images Sa in the case of a synchronization between transmission and acquisition whose frequency is twice that of the program. Figure 4d is the result of the subtraction of images taken two to two consecutive. When in the image N, the source does not emit light and the image N + 1 is lit, the result is a positive pulse P +. On the other hand, if in the next image N + 2, the source is again extinguished, the result is a negative pulse P_. In the case where the acquisition, which takes place with a frequency equal to twice that of light emission, is not synchronized with the emission, as shown in Figure 4ef the result of the subtraction of two consecutive images is presented, in the most unfavorable configuration, in the form of two energy pulses halved compared to the case of the synchronization between transmission and acquisition (Figure 4f), referenced p + or p_ depending on whether the source emits or not the light in the image N.

  The telecom optronic unit 14 will detect the high frequency modulation Fooms of the optical signal. More precisely, it is a photodetector such as a photodiode whose bandwidth makes it possible to acquire the optical signal modulated at the telecommunication frequency Fooms • According to FIG. 4b, it is understood that the pulse produced according to the first level modulation is broken down into two series of sub pulses. The first series of sub pulses aims to synchronize the acquisition of video images with the generation of pulses at the emission frequency Fe by the light sources. It can therefore be found only in the configuration described in Figure 40 with regard to the synchronization between the optical source and the acquisition of the video image. Indeed, the telecommunication frequency Fooms is 100 times to 10000 times higher than the emission frequency Fe. Once the synchronization subpulses of the high frequency modulation of the signal detected by the telecom unit 14 as shown in FIG. 5, the telecommunication unit 14 transmits the information to the video unit 12 which can then trigger an acquisition synchronized with the production of the pulse by the light source. The configuration described in FIG. 4e corresponds to the case where the telecommunication unit 14 is no longer operational for any reason. This unfavorable configuration shows that the system can still operate in degraded mode. The consequence of the malfunction of the telecom unit 14 resulting in a decrease in the range of the detection system since for identical conditions, the optical signal received by the video unit 12 in the worst case is twice as low as the optical signal received by the video unit 12 in the optimal case, that is to say when the acquisition of the image is perfectly synchronized with the emission of light pulses by the light sources of the target vehicle. The coding of the information of the synchronization sub pulses must simply respect the constraints necessary to obtain a good synchronization between the sources of illumination and the acquisition of video images, that is to say to allow a response time as short as possible. The merit of the invention lies in the fact that the detection of this high frequency synchronization code Fooms makes it possible to make the detection of the light pulses by the video unit 12 more robust and more reliable because this redundant information is mutually reinforcing (cooperation and Data fusion). The sub pulses of information (FIG. 5) can contain all the information useful for the application concerned with regard to the target vehicle: speed, braking action, mass, stiffness, etc. The coding of this information is arbitrary.

  Thus, the invention also relates to a method of operating the receiving device 10 of the assistance system, the steps of which are the following: (a) reception of pulses received with a telecommunication frequency Fooms by a telecommunication unit 14 of the receiving device 10; and (b) then triggering the acquisition of the pulses at a transmission frequency Fe by a video unit 12, said triggering being generated by receiving pulses received with said telecommunication frequency Fooms. Following these two successive major steps, the image of the road scene is acquired and digitized by means of digitization 16 of the video reception unit 12, the high frequency signal Fooms is also digitized by such means 18 to extract the image. information of this signal, such as the speed of the target vehicle, however it is not used directly for image analysis. This data is then transmitted to data processing means 20, such as software for calculating and predicting the trajectory of the vehicle as explained hereinafter. In the case where the pulsed light, emitted in addition to the headlights equipping the vehicle, comes from several elementary sources forming a geometric pattern, the latter allow, by simple geometric calculations from the collected images, to directly obtain the vector distance between the assisted vehicle and the target to be detected, and to deduce a speed vector with a very good accuracy. Thanks to such robust and accurate information obtained at a sufficient frequency, it is possible to calculate and predict the relative trajectory between the detector vehicle and the detected object. Such an environmental detection driving assistance system can advantageously be used to carry out the service listed under the name Stop and Go in a traffic jam situation, that is to say, frequent starts. in case of heavy traffic at low traffic speed. The stop-and-go stopper method then comprises the following steps, represented in FIG. 6. Once the process has been initialized (step a), the driver can define the parameters of the system (step b), namely: the tracking distance ; - the target detection mode; - the mode of control of the assisted vehicle; - the speed threshold to deactivate the process.

  The tracking distance between the assisted vehicle and a target in front of it can be set by the driver or the system uses the default setting with the last stored values. The target detection mode can notably use the assistance system according to the invention with an ASL pulsed light source. An appropriate human-machine interface will inform the driver of the vehicle of the presence of a detected obstacle. This detection mode will make the detection more reliable than if it were performed without an SSL light source. The automatic longitudinal and lateral control of the vehicle assumes a detection of the markings on the ground, of which the white line continues, and may be chosen by the driver. Without a method of detecting ground markings, the detection of only the targets placed in front of the vehicle, by the pulsed light source system, makes it possible to control the longitudinal advance of the vehicle by controlling acceleration and braking while the driver takes care of the lateral movement of the vehicle via the steering wheel.

  The driver finally sets a speed threshold beyond which the driving assistance method is disabled, by issuing a message to the driver who takes control of the progress of the vehicle. When the method is activated in step c) by the driver, by means of any type of manual control, voice, automatic, cork or traffic situation slowed down, target detection takes place by the system according to the invention from pulsed light sources (step d). A video sensor as defined above will acquire a succession of images at a frequency greater than the emission frequency of the light sources and send them to an ASIC algorithm for example that will, in real time, to differentiate between two consecutive images N and N + 1 in order to extract the images alone from the pulsed sources. The position and the contours of the detected light sources are transmitted to a central unit, managing all of these sources, to identify the predefined patterns of the sources according to the type of target vehicle seen by its rear face, or lateral, or before. The CPU also tracks their evolutions in time-tracking and predicts their future positions - prediction. When the light patterns detected are part of the predefined patterns stored in the central unit, the information is directly transferred to the computers that manage the human-machine interface and the longitudinal control of the vehicle. On the other hand, if these light patterns are not recognized by the central unit, a message is sent to the driver, which may or may not validate the detection, so that the new light pattern is then stored in the base of the light source patterns. . If the driver invalidates this detection, he regains control of the driver assistance system. If, in addition, the vehicle is equipped with means for detecting the ground markings (step e) and the detection of a target is validated in step f), the automatic vehicle progress control mode is set to road, with longitudinal and lateral help (step g). In the case where the detection of the targets takes place conventionally by a system without pulsed light source, the detection of an obstacle must be validated in step h). In the case where the vehicle is not equipped with white line detection means on the ground, the lateral control mode of the vehicle is not assured, only the longitudinal control is implemented (step i).

  Thus, thanks to the driving assistance system according to the invention, using pulsed light sources whose signal is captured by a video camera, the method follows the target vehicle keeping the set distance predetermined by the driver. There are several situations of exit of the control of the vehicle in automatic mode, which are defined in particular by the loss or the degradation of the detection of the light sources, not allowing any more to appreciate the inter-vehicle distances in the case of a detection by pulsed light sources, or by the loss or degradation of the quality of detection of the target vehicle by conventional means such as the quality of the detection of ground markings. It can also be when the speed of the vehicle followed exceeds the predefined threshold speed, when the processing of the inter-vehicle surveillance image detects an object movement between the occupied vehicle and the target vehicle or even when a door or the trunk of the vehicle is open. If this is the case, the driver must regain control of the vehicle and validate the recovery in hand by any means touch, voice, control of acceleration or braking, etc. The advantage of the assistance system according to the invention is to guarantee high reliability in the delivery of Stop and Go because the pulsed sources are associated with a simple and robust algorithm for detecting a target, its identification as a vehicle thanks to their specific motives and calculation of inter-vehicle distance thanks to the standard spacing between the elementary light sources at the rear of the target vehicle. In addition, the loss of partial or complete detection of pulsed light sources by the video camera makes it possible to quickly and reliably detect the insertion of an object, such as a motorcycle or pedestrian, into the space between the vehicle and target.

Claims (12)

  1. On-board driving assistance system in a motor vehicle for the detection of the environment, said embedded system comprising a receiving device (10) for detecting a signal emitted by a light emitting device on board a target to be detected, characterized in that said receiver device (10) comprises a first (12) and a second (14) receiving unit respectively allocated to a first (Fe) and a second frequency (Fcoms) of said distinct light signal emitted by said transmitting device.   Driver assistance system according to Claim 1, characterized in that the two units are communicating with each other, the first unit (12) being informed of the arrival of the first frequency (Fe) by the detection of the second frequency (Fooms) by the second unit (14).   3. Driving assistance system according to one of claims 1 or 2, characterized in that the second frequency (Fcoms) is higher than the first frequency (Fe), preferably 100 to 10000 higher.   Driver assistance system according to one of the preceding claims, characterized in that the second received signal with the second frequency (Fooms) occurs within the first received signal at the first frequency (Fe). 25   Driving assistance system according to one of the preceding claims, characterized in that the first unit (12) of the receiving device (10) is a video unit and the second unit (14) of the receiving device (10) is a telecom unit, the telecom unit (14) being able to warn the video unit (12) of the arrival of the first signal.   Driver assistance system according to one of the preceding claims, characterized in that the first unit (12) of the receiver device (10) comprises a video camera sensitive to visible and / or near infrared radiation, the image acquisition frequency is greater than the emission frequency (Fe) of the pulsed sources carried by the target, said camera being associated with image processing means for delivering the optical information produced by the target, and said acquired image processing means performs a subtraction of consecutive images, acquired in a short time interval and in particular between 1 ms and 25 ms, for delivering the new optical information between two consecutive images received by the first unit the receiving device (10).   Driver assistance system according to Claim 6, characterized in that the acquired image processing means calculate, from the optical information received from the detected target, at least the distance between the assisted vehicle and the vehicle. detected target or their relative velocities, or predict the relative trajectory between them.   8. Driving assistance system according to one of the preceding claims, characterized in that the second unit (14) of the receiver device (10) comprises an optronic component whose bandwidth makes it possible to acquire the second modulated optical signal. at a telecommunication frequency (Fcoms), said optronic component comprising for example a photodetector, preferably a thermal photodetector or a quantum photodetector.   9. Driving assistance system according to one of the preceding claims, characterized in that it is used in combination with a starting system and automatic shutdown of said assisted vehicle.   10. A method for assisting the driving of a motor vehicle for the detection of the environment, said vehicle comprising a receiving device (10) for the detection of a signal emitted at two frequencies by a light emitting device on board. a target to be detected, characterized in that it comprises the following steps: (a) reception of pulses received with a telecommunication frequency (Fcoms) by a telecom unit (14) of the receiver device (10); and (b) then triggering the acquisition of the pulses at a transmission frequency (Fe) by a video unit (12), said triggering being generated by receiving pulses received with said telecommunication frequency (Fcoms).   11. The method of claim 10, characterized in that subtracted consecutive video images, for delivering the new optical information between two consecutive images received by said video unit (12). 10   12. Method according to one of claims 10 or 11, characterized in that controls a starting device and automatic shutdown of said vehicle with the embedded system. 15