EP0384794B1 - Traffic and parking information collecting and broadcasting system for transport vehicles, especially for motorists - Google Patents

Abstract

This system comprises: - information-collecting means (100) for gathering and centralising a set of information relating to the state of the traffic in a given zone, in particular an urban zone, each item of information corresponding to a segment included between two predetermined characteristic sites, - means (210) for transforming this set of information into a series of elementary digital information each consisting of an identifier of segment and of direction of flow and of a state variable representing the state of traffic of this segment in the said direction of flow; - means (220) for formulating, on the basis of this series of digital information, a scrolling, continuous and cyclic sequence of information consisting of the elementary digital information from all the relevant segments, this sequence being regularly updated as a function of the change in the information gathered; - means (330, 340, 350) for broadcasting this scrolling sequence of information over the air; and - on board the said vehicles: means (360) of receiving the said scrolling sequence of information thus broadcast, discriminator means (240) for selecting, from the set of elementary information, that likely to interest the driver, as a function of a predetermined criterion inserted by the latter; and means for presenting the driver with the elementary information thus picked out. <IMAGE>

Description

The present invention relates to a system and method for collecting and disseminating information on the circulation and parking of transport vehicles, intended in particular for motorists.

It is common to broadcast information bulletins during radio broadcasts warning motorists of traffic difficulties (traffic jams, accidents, etc.) on certain arteries or at certain traffic nodes in a built-up area.

This information can only be ad hoc information, in a limited number, and it is also not personalized according to the driver, who will indiscriminately receive all of the messages thus broadcast.

The device described in EP-A-290679 receives a large amount of traffic information and makes it possible to select the messages concerning an area of interest to the user, but does not solve the problem of collecting information, and cannot provide personalized guidance information.

It is for this reason that we have recently developed specific guidance systems which provide each driver with personalized information on the route he must follow, indicate alternate routes if necessary, allow him to locate its position in the city, etc.

We can notably cite the system developed by Siemens AG with the assistance of the University of Berlin and Robert Bosch GmbH under the name Aliscout , which is based on a system of bidirectional infrared data exchange between the vehicles to be guided and beacons placed at different crossroads.

In this system, each automobile is equipped with various sensors (distance traveled, speed, steering compass, etc.) and a transceiver operating as an answering machine.

When approaching a crossroads, and on reception of an interrogation signal emitted by the beacon of this crossroads, the responder of the vehicle will transmit to the beacon the information collected by the sensors of this vehicle. This information will then be transmitted by the beacon to a central computer which will compare this information with homologous information given by the same vehicle to the previous beacon and will determine the traffic flow and drift possible real trajectory of the vehicle compared to the initially planned trajectory.

In return, the host center will send guide information to the beacon which will be transmitted to the vehicle by the beacon. This guidance information will for example appear on a screen in the form of an arrow indicating to the driver the direction to take to reach the next beacon of his route (or, if the host center has determined that this is preferable, the next beacon of 'an alternate route), as well as the distance as the crow flies to it.

Such a system is for example described in a document entitled LISB Leit- und Informationssystem Berlin -ALISCOUT im Großfeldversuch, published by Siemens AG under the reference A 1900-N9-11, as well as in EP-A-0 029 201 and EP- A-0 292 897.

• Du point de vue de l'infrastructure au sol, notamment du fait de la densité élevée de balises de carrefour nécessaire à un fonctionnement satisfaisant du système en milieu urbain, il est nécessaire d'installer un système qui soit entièrement nouveau (sans possibilité de réutiliser les équipements souvent existants tels que les systèmes déjà en place destinés à la régulation de la circulation par synchronisation des feux tricolores) et sans possibilité de mise en place progressive - d'où des investissements très lourds pour la collectivité. En outre, ce système nécessite un nombre important de liaisons bidirectionnelles à la fois entre balises et véhicules et entre balises et centre serveur. L'augmentation du nombre de balises de carrefour nécessite donc une augmentation corrélative de la taille du réseau, ce qui limite les possibilités de généralisation rapide du système, compte tenu du coût et de la complexité qu'entraîne une telle infrastructure.
• Du point de vue des équipements embarqués par chacun des véhicules souhaitant participer au système, ceux-ci devront tous être pourvus non seulement d'un équipement émetteur/récepteur infrarouge et d'un certain nombre de capteurs permettant au système de connaître leurs déplacements, mais aussi d'une interface sophistiquée permettant au conducteur d'être guidé par l'intermédiaire d'un écran et d'un synthétiseur vocal. Cet ensemble très complet représente pour l'équipement individuel un coût important.

Obviously, such a system, although effective, is extremely cumbersome and expensive to set up. Indeed:

• From the point of view of the ground infrastructure, in particular due to the high density of crossroad beacons necessary for satisfactory operation of the system in urban areas, it is necessary to install a system which is entirely new (without possibility of reusing often existing equipment such as systems already in place intended for traffic regulation by synchronization of traffic lights) and without the possibility of progressive installation - hence very heavy investments for the community. In addition, this system requires a large number of bidirectional links both between beacons and vehicles and between beacons and server center. The increase in the number of crossroad beacons therefore requires a corresponding increase in the size of the network, which limits the possibilities of rapid generalization of the system, taking into account the cost and the complexity that such an infrastructure entails.
• From the point of view of the equipment on board by each of the vehicles wishing to participate in the system, these must all be provided not only with transmitter / receiver equipment infrared and a number of sensors allowing the system to know their movements, but also a sophisticated interface allowing the driver to be guided via a screen and a voice synthesizer. This very complete set represents a significant cost for individual equipment.

Finally, it appears that there is a potential clientele of motorists who would simply like to benefit from precise and personalized information on the traffic status of the route they plan to take; this in order to adapt or modify this itinerary accordingly taking into account the knowledge that they already have places, without having to submit to automatic guidance of which they are not masters.

• pour la collecte des informations, utilise, en complément ou en variante du système précité, d'autres techniques et d'autres systèmes existants d'acquisition de données - notamment les systèmes déjà en place destinés à la régulation de la circulation par synchronisation des feux tricolores, et
• pour la diffusion des informations, permette de proposer à un large public d'utilisateurs la diffusion d'informations par un canal adapté, en complément du système de guidage des abonnés ayant choisi ce système.

The invention aims to remedy the drawbacks of the above system, by proposing a system for collecting and disseminating information which:

• to collect information, use, in addition to or as a variant of the aforementioned system, other techniques and other existing data acquisition systems - in particular the systems already in place intended for traffic regulation by synchronization of lights tricolor, and
• for the dissemination of information, makes it possible to offer a wide audience of users the dissemination of information through a suitable channel, in addition to the guidance system for subscribers who have chosen this system.

It will indeed be seen that, although simplified compared to the aforementioned known system, the system of the invention can be implemented for a low cost in each vehicle wishing to take advantage of the information produced and disseminated by the system of the invention.

In addition, and as will also be explained, the increase in the number of these vehicles does not entail any need to increase the transmission capacity of the network leading to the server center.

Despite this, as will be seen, the driver equipped with a receiver of the information broadcast by the system according to the invention will be able to know the state of traffic on the entire route it plans to take - and only on this route - as well as, if applicable, on areas adjacent to this route.

Selectively presenting information to the driver according to the route he has chosen makes it possible to provide very fine information (the agglomeration being for example divided into a thousand sections or characteristic places of which the state can be known each person’s traffic), while only supplying information of interest to the driver given his route, for example information relating to ten or fifteen sections or characteristic places.

To this end, the system of the invention includes the features set out in claim 1. The invention also covers a corresponding method, set out in claim 12.

• soit utiliser le système complet décrit plus haut, ce qui permettra d'assurer le guidage des véhicules flottants, qui sont par nature des véhicules auquel ce guidage est le plus utile,
• soit n'utiliser qu'un système simplifié, avec une liaison unidirectionnelle de la balise vers le centre serveur et sans système de décodage et d'affichage des informations de guidage à bord des véhicules. Un tel système simplifié n'assurerait que la seule fonction d'analyse du trafic par suivi des véhicules flottants, nécessaire mais suffisante à la mise en oeuvre du système de l'invention.

The means of collecting information can for example integrate the aforementioned Aliscout system. However, in this case, only a limited number of vehicles will be fitted (which will be called in the following description "floating vehicles") which will serve as control vehicles and which will be chosen from vehicles which circulate intensively. (taxis, buses, couriers, public service vehicles, etc.). We can then:

• either use the complete system described above, which will ensure the guidance of floating vehicles, which are by nature vehicles for which this guidance is most useful,
• or use only a simplified system, with a unidirectional link from the beacon to the server center and without a system for decoding and displaying guidance information on board vehicles. Such a simplified system would only provide the sole function of traffic analysis by tracking floating vehicles, necessary but sufficient for the implementation of the system. of the invention.

Advantageously, the scrolling sequence of information is broadcast over the air by a method of broadcasting digital data with subcarrier added to a broadcast transmission signal, the receivers on board vehicles being broadcast receivers equipped with a decoder ensuring separation of digital signal information from audio program signal.

One can in particular use for this purpose the system RDS ( Radio Data System ) for the diffusion of digital data by radio in frequency modulation, and whose specifications were defined by the European Radiocommunication Union, these specifications being in particular detailed in the document referenced Tech. 3244 published in March 1984 by this organization.

Indeed, the specifications of the RDS system provide for the possibility, in addition to the dissemination of a certain number of standard information (type and name of the transmitter, other frequencies of emission of the same program, time and date, radio text information) to have "data channels for external use" allowing the transmission of messages of any length and format and which can convey alphanumeric characters or any other digital data.

The reception by RDS of traffic information messages is for example described in EP-A-0 290 679, EP-A-0 263 332 or EP-A-0 300 205.

The advantage of the RDS system is that it can be used by simple car radios fitted with an appropriate decoder, and of which various models are currently available or under development. To use the guidance information of the invention, it will then suffice to connect to the digital data output of the car radio a box comprising the appropriate circuits and control means.

Compared to a guidance system such as the aforementioned Aliscout system, this saves both the specific data dissemination system (which is, in the case of the invention, a transmitter FM radio already existing, of which it is enough only to code in an appropriate way the signal on the emission) and of the specific receiver on board the vehicle, which could be a simple car radio provided with an RDS decoder.

Alternatively, instead of using the carrier frequency of one or more radio stations, other radio frequencies could possibly be used.

Other advantageous features are set out in the dependent claims.

We will now give a detailed example of implementation of the invention, with reference to the appended figures.

FIG. 1 is a block diagram of the system of the invention, showing the various functions implemented.

Figure 2 is a representation of a route chosen by the driver and the surrounding characteristic places thereof.

In FIG. 1, the reference 100 designates the information collection system which can be, as indicated above, a coupling of a complete or simplified Aliscout type system to systems based on loops put in place for traffic regulation by synchronization of traffic lights.

This system essentially comprises a set 110 of elements installed on board floating vehicles (as defined above, that is to say control vehicles in limited number chosen from vehicles circulating intensively), beacons 120 installed in a certain number of places, and a server center 130 centralizing and processing the information collected by the beacons.

The elements 110 on board the floating vehicles essentially comprise an on-board computer 111 receiving the signals coming from an electronic compass 112 giving the absolute orientation of the vehicle relative to magnetic North and an odometer 113 counting the number of turns wheel (therefore the distance traveled) since the last beacon. A keyboard 114 makes it possible to introduce a certain number of information such as a vehicle identifier, necessary to be able to locate and follow a vehicle from one beacon to another.

The computer 111 communicates with an infrared responder 115 receiving from the beacon 120 an interrogation signal and returning to the latter, on reception of this interrogation signal, the values measured by the sensors.

Each beacon 120 comprises, for example mounted on a three-color light 121, an infrared transceiver 122 exchanging information with the vehicles of the system, as well as a computer 123 managing these exchanges of information and ensuring the interfacing with the server center 130 .

The server center 130 makes it possible both to calculate the route (block 131), when the possibilities (not necessary for the implementation of the invention) of specific guidance of floating vehicles are used by sending information via the beacon, and the analysis of the traffic according to the information collected, with possible visualization (block 132).

Characteristically of the invention, the information produced by block 132 is used to develop information elementary numbers representing the state of traffic in each characteristic location of the agglomeration.

• soit, définissent un tronçon orienté (vecteur défini par ses deux lieux caractéristiques d'origine et d'extrémité) pour lequel l'état du trafic des véhicules est une information déterminante pour la régulation de ce trafic, typiquement des artères de circulation (avenues, boulevards, voies rapides) ou des sections d'artères,
• soit, éventuellement, correspondent à des aires de stationnement dont l'état d'occupation (taux d'occupation) par des véhicules est une information déterminante pour la régulation du trafic.

By “characteristic places”, we mean different places in the agglomeration which:

• or, define an oriented section (vector defined by its two characteristic places of origin and end) for which the state of vehicle traffic is decisive information for the regulation of this traffic, typically traffic arteries (avenues, boulevards, expressways) or sections of arteries,
• or, possibly, correspond to parking areas whose occupancy status (occupancy rate) by vehicles is decisive information for traffic regulation.

The choice of characteristic places and sections is made in order to achieve a complete network of the agglomeration, while making it possible to describe almost all the possible routes in a simple and unambiguous way.

It is thus estimated that, for an agglomeration such as Paris intra muros , a thousand sections and parking areas should make it possible to report on the state of traffic in a sufficiently complete and detailed manner.

It is important to provide a parameter for indicating the direction of circulation, either by using for example a specific coding bit, or by designating the section by its two ends, the direction then being determined by the order in which these are stated. two ends (AB corresponding to one of the directions, and BA to the other).

Indeed, the traffic can be fluid in one direction and congested in the other, so that, if one did not distinguish the direction of traffic, one would deliver to the driver information which would not be representative of the real situation.

Each oriented section (or each characteristic location, in the case of a parking area) will be associated with a "state variable", which will be information representative of the traffic status of this section (or the rate of occupancy by vehicles, in the case a parking area).

To determine this "traffic state", a certain number of classes of relative levels of deceleration are defined, expressed in relative values of a journey time on the section concerned. The state variable is then the digital information identifying the class to which the effective deceleration level belongs, that is to say the one that has been calculated, at the instant considered, from the various information collected. upstream.

At a minimum, we could only code the state variable on a single bit (which would give two states: fluid / congested), but we preferably code it on a larger number of bits, for example two or three bits, which makes it possible to provide more nuanced information (four possible states on two bits, eight possible states on three bits, etc.).

• «fluide», pour un niveau relatif de ralentissement compris entre 0 % et 10 % (c'est-à-dire pour un temps de parcours effectif compris entre t_m et 1,10.t_m) ;
• «dense», pour un niveau relatif de ralentissement compris entre 10 % et 50 % (c'est-à-dire pour un temps de parcours réel compris entre 1,10.t_m et 2.t_m) ;
• «ralenti», pour un niveau relatif de ralentissement compris entre 50 % et 75 % (c'est-à-dire pour un temps de parcours réel compris entre 2.t_m et 3.t_m) ;
• «bouché», pour un niveau relatif de ralentissement supérieur à 75 % (c'est-à-dire pour un temps de parcours réel supérieur à 3.t_m); et
• «indéterminé», lorsqu'il n'est pas possible de déterminer le niveau de ralentissement, ou lorsque la valeur déterminée pour celui-ci est entachée d'une telle incertitude que cette valeur n'est plus significative.

Thus, if the journey time in the event of total fluidity (minimum journey time taking into account speed limits, sequences of traffic lights, etc.) is t _m minutes on the oriented section considered, we could define for example the following five retardation classes:

• "Fluid", for a relative level of deceleration between 0% and 10% (that is to say for an effective travel time between t _m and 1.10.t _m );
• "Dense", for a relative level of deceleration between 10% and 50% (that is to say for an actual journey time between 1.10.t _m and 2.t _m );
• "Slowed down", for a relative level of deceleration between 50% and 75% (that is to say for an actual journey time between 2.t _m and 3.t _m );
• "Blocked", for a relative level of deceleration greater than 75% (that is to say for an actual journey time greater than 3.t _m ); and
• "Indeterminate", when it is not possible to determine the level of deceleration, or when the value determined for it is marred by such uncertainty that this value is no longer significant.

Of course, the numerical values given above are only for illustrative purposes; it will also be noted that they are not necessarily the same for the entire network but that, on the contrary, it may be advantageous to give the respective levels of slowdown values depending on the section concerned, typically as a function of the topography of this section and the corresponding type of road (expressway or crossroads).

In addition, in practical terms, and to avoid instability of the indications, the actual values of the thresholds thus determined may be lowered by 10% in the event of increasing congestion, and increased accordingly during a phase of return to a normal situation .

• '001' pour la classe «fluide» ;
• '010' pour la classe «dense» ;
• '011' pour la classe «ralenti»
• '100' pour la classe «bouché» ; et
• '101' pour la classe «indéterminé».

The state variable will then be the digital information designating the deceleration class to which the actual deceleration level belongs at the instant considered, for example:

• '001' for the class "fluid";
• '010' for the “dense” class;
• '011' for the “idle” class
• '100' for the “plugged” class; and
• '101' for the class 'undetermined'.

It will be noted that, in all cases, the state variable is determined in an exclusively relative manner, that is to say that, although being a quantitative variable, it is never delivered to the motorist in the form of a journey time, but in the form of a relative value of traffic flow ("fluid", "dense", "slowed down", "blocked"), the only one that is easily and directly perceptible by the driver.

It will also be noted that, very advantageously, the state variable is always given an unambiguous value, even if the information to which it corresponds could not be determined. This allows, on board the vehicle, to immediately determine and report to the driver the existence of a reception anomaly if, for example, a value such as '000' is obtained at the output.

• '001' pour une occupation effective comprise entre 0 et 0,2.C ;
• '010' pour une occupation effective comprise entre 0,2.C et 0,7.C ;
• '011' pour une occupation effective comprise entre 0,7.C et 0,9.C ;
• '100' pour une occupation effective comprise entre 0,9.C et C ; et
• '101' lorsque l'occupation effective n'est pas connue.

If the state variable must represent the state of occupation of a parking area with a capacity of C vehicles, we can then, for example, choose from the following five numerical values:

• '001' for an effective occupation between 0 and 0.22C;
• '010' for an effective occupation between 0,2.C and 0,7.C;
• '011' for effective occupancy between 0.77C and 0.9.C;
• '100' for effective occupancy between 0.9.C and C; and
• '101' when the actual occupation is not known.

As for the slowdown classes, in practical terms, and to avoid instability of the indications, the actual values of the thresholds thus determined may be lowered by 10% in the event of increasing congestion, and increased accordingly during a return phase to a normal situation.

• analyse de la circulation de véhicules flottants par l'ensemble 100 décrit plus haut et illustré à la figure 1, l'emplacement des balises 120 pouvant éventuellement correspondre à celui d'un certain nombre de lieux caractéristiques,
• capteurs magnétiques utilisés pour la régulation des feux de circulation,
• comptage des entrées/sorties dans les parkings,
• caméras, informations transmises par les voitures de police, etc.

The state variables that we have just defined can be obtained from different sources:

• analysis of the circulation of floating vehicles by the assembly 100 described above and illustrated in FIG. 1, the location of the beacons 120 possibly being able to correspond to that of a certain number of characteristic places,
• magnetic sensors used to regulate traffic lights,
• counting of entrances / exits in car parks,
• cameras, information transmitted by police cars, etc.

To simplify the preparation of the information in block 210, it is desirable to collect this information from a system which is as automated and as homogeneous as possible.

It is for this reason that we prefer to collect most of this information from beacons interrogating floating vehicles. However, the system of the invention does not exclude, as a variant or in addition, the use of other modes of data collection.

Block 210 thus develops a series of digital information elementary each consisting of an oriented segment identifier and a state variable, as defined above.

Preferably, it will be possible to manually force the value of certain state variables, for example by means of an input console 230, in order to deliberately influence the course of traffic, regardless of the state of traffic. A typical case is that where one wishes to clear a crossroads by diverting the vehicles which planned to pass there.

• '110' pour «à éviter» ; ou
• '111' pour «interdit».

We then provide additional values for the state variable, for example:

• '110' for “to avoid”; or
• '111' for 'forbidden'.

It will be noted that, in these latter cases, the state variable no longer represents a calculated value which is the image of an actual situation (degree of deceleration), but forced information from a command post.

This block 210 can also weight the information which it produces as a function of a certain number of parameters, so as to adapt the messages broadcast to the circumstances or to anticipate a probable development.

• le degré d'évolution de la variable d'état entre sa valeur instantanée et sa valeur précédente,
• la valeur de la variable d'état la veille à la même heure (compte tenu des jours fériés, chômés, etc.)
• la valeur de la variable d'état le même jour l'année précédente,
• les valeurs des variables d'état de certains tronçons et/ou lieux caractéristiques voisins (afin d'anticiper les réactions en chaîne, par exemple en cas d'accident en un point d'une artère).

The weighting factors can, among others, be:

• the degree of evolution of the state variable between its instantaneous value and its previous value,
• the value of the state variable the day before at the same time (taking into account public holidays, non-working days, etc.)
• the value of the state variable on the same day the previous year,
• the values of the state variables of certain neighboring sections and / or characteristic places (in order to anticipate chain reactions, for example in the event of an accident at a point on an artery).

The elementary digital information produced by block 210 is then grouped (block 220) to develop a "segment of information" made up of all of the elementary digital information, placed end to end, of all the sections of the agglomeration (as well as characteristic places thereof corresponding to the parking areas whose occupancy status is to be disseminated).

The segment thus developed will constitute a scrolling sequence of information, continuous and cyclic, which will be the subject of coding, advantageously the RDS coding mentioned above.

The type of modulation used in RDS is amplitude modulation with two sidebands with carrier suppression and two-phase differential coded signals. Such coding allows, for a total transmitted bit rate of 1187.5 bits per second, a useful information bit rate of 730 bits per second for all of the information transmitted, approximately 80 bits per second being reserved for the data channel to external use, which is the route used by the present invention to transmit guidance signals.

As it scrolls, the segment will be updated, the periodicity of the scrolling then corresponding to the periodicity of the update.

In the example cited above of 1000 sections and parking areas, if we choose a state variable with 10 positions, we can code the elementary digital information on 16 bits which, once grouped together, will form a segment of 16 000 bits. If we consider that the RDS coding authorizes a useful bit rate of information of 80 bits per second, we can have a periodicity of scrolling of the system (and therefore of updating information of 200 seconds, or 3 ′ 20˝, value fully compatible with efficient guidance in built-up areas, even in the presence of rapidly changing traffic conditions.

• le nombre de tronçons et aires de stationnement,
• le nombre de positions de la variable d'état, et
• la périodicité de défilement du segment.

Of course, these values are given only by way of example. Given the specific cases, and with the constraint of the maximum speed allowed by the data dissemination system, a compromise must be sought between:

• the number of sections and parking areas,
• the number of positions of the state variable, and
• the periodicity of scrolling of the segment.

The elementary digital information segment thus coded is broadcast to the vehicle by a broadcasting chain comprising transmitter means 310 to 350 and a receiver 360 in each vehicle.

On transmission, the audio signal coming from a recording control room (block 310) is transformed (block 320) into a modulation signal in a conventional manner, for example with stereo coding at pilot frequency. The audio signal is then multiplexed (block 340) with the signal from the RDS coder (block 350), for example on a sub-carrier at 57 kHz (harmonic 3 of the sub-carrier of the stereo pilot signal at 19 kHz).

The signal thus multiplexed is directed to a frequency modulation broadcasting transmitter 330 of the conventional type.

In addition, the various vehicles are equipped with 360 receivers, which are car radio receivers equipped with conventional RDS decoders.

The digital output of the data channel for external use of the RDS 360 receiver is connected to a box 240, specific to the invention, which will therefore receive from this output, continuously, the scrolling sequence of information broadcast by the system.

The elementary digital information will be decoded and presented to the driver in clear visually on a screen and / or by text-to-speech means 260.

However, the driver is not presented with all of the information disseminated.

Indeed, given the large number of sections and parking areas (a thousand, in the example considered) and the relatively high periodicity (3.2 minutes) of the scrolling, the motorist would hear an uninterrupted series of messages, and would have a hard time hearing and retaining only the messages that interest him, and this at the cost of attention prejudicial to his safety.

Provision is therefore made in the housing 240 for discriminating means for selecting, from among all of the elementary digital information, only that likely to interest the driver, as a function of one or more predetermined criterion (ies) introduced. (s) by the latter by means of a keyboard 250.

This selects the relevant messages and only returns these relevant messages.

The predetermined criterion may in particular include a route, composed directly on the keyboard 250 by the driver (or selected indirectly, as will be explained below, from information entered by the latter) from one on which will be clearly indicated the different characteristic places of the agglomeration and their identification code (the code to type on the keyboard).

The driver can thus compose for example (Figure 2) the route ABCDE.

In this case, for each elementary digital information received, the unit 240 will test the segment identifier of this information and will not return to the driver the corresponding state variable unless this segment identifier corresponds to the previously chosen route (c ' ie, in the example illustrated, the only state variables of successive sections AB, BC, CD and DE); the driver will therefore only receive the relevant messages - in the example illustrated, four messages out of a total of one thousand messages received.

• la mise en mémoire de plusieurs itinéraires préconstitués, qui seront rappelés par une simple pression de touche ;
• le codage, pour un même couple origine/destination, de plusieurs itinéraires alternatifs que le conducteur pourra tester l'un après l'autre ;
• l'incorporation à un itinéraire donné de variantes qui seront restituées en même temps que l'itinéraire lui-même ;
• l'interrogation isolée d'un tronçon donné ou d'une aire de stationnement donnée.

It is possible to provide a number of variants or improvements:

• the storage of several pre-arranged routes, which will be recalled at the press of a button;
• the coding, for the same origin / destination pair, of several alternative routes that the driver can test one after the other;
• the incorporation into a given route of variants which will be restored at the same time as the route itself;
• isolated interrogation of a given section or of a given parking area.

Furthermore, provision can be made not only for information relating to the sections of the chosen route (ABCDE, in the example illustrated), but also to neighboring sections (marked out by black dots in FIG. 2, the corresponding white dots at the characteristic places staking out sections for which information is not returned to the user).

A more or less wide “corridor” is thus defined around the route, the width of this corridor depending on the number of intermediate points between the origin and the destination that the user has provided to the device.

By thus disseminating to the driver information relating to the chosen route and its immediate environment, it is possible to take into account any deviations, during the journey, from the planned route.

Claims (21)

1. A system for collecting and broadcasting information concerning vehicle traffic and parking, in particular for car drivers, comprising:

   - information-collecting means (100) for collecting and centralizing information relating to the state of traffic in a given zone, in particular a built-up area, said zone being described by a lattice of segments extending between predetermined pairs of reference locations, each individual record in said centralized information corresponding to a respective segment;

   - means (210) for transforming this centralized information into a series of individual digital messages each constituted by an identifier specifying the segment and the direction of travel over said segment and a state variable representative of the state of the traffic on said segment in said travel direction;

   - means (220) for generating a running sequence of messages based on said series of individual digital messages, said running sequence being continuous and cyclic and being constituted by the individual digital messages corresponding to each of the segments under consideration, said sequence being regularly updated as a function of changes in the information as collected;

   - means (330, 340, 350) for broadcasting said running sequence of messages by radio; and

   - on board said vehicles: means (360) for receiving the running sequence of messages broadcast in this way; discriminator means (240) for selecting those individual digital messages from amongst the set of messages of the running sequence of information thus received that may be of interest to the driver as a function of predetermined selection criteria entered thereto by the driver; and means for presenting the individual messages selected in this way to the driver,

   said system being characterized in that:

   - said information-collecting means (100) comprises transmitting and/or receiving beacons (120) co-operating with responders (115) installed on a traffic-sampling subset of vehicles constituting a sample of all of the vehicles constituting the traffic, said traffic-sampling vehicles being provided with means for providing said beacons, via said responders, with information concerning their own progress within said zone, and/or information originating from sensors for distance travelled (113) and/or travel direction (112), said system further being possibly adapted to collect information originating from magnetic pick-ups used for controlling traffic lights and/or from means for counting vehicles entering and leaving car parks and/or from video cameras and/or information provided by police cars, and in that

   - said means (210) for transforming said centralized information collected into a series of individual digital messages derives from said information, for each segment and direction of travel under consideration, respective travel times (t_m) on the basis of which are determined the corresponding state variables.
2. The system of claim 1, in which said state variable is a digital value ('001', '010', '011', '100') designating, amongst a plurality of classes of hold-up degrees ("fluid"; "dense"; "held-up"; "jammed"), the class to which the effective degree of hold-up at a given instant for the segment and direction of travel under consideration belongs, said hold-up degree being a relative degree (x.t_m, with x≧1) expressed with respect to said travel time (t_m) determined for the segment and direction of travel under consideration upon a situation of total fluidity.
3. The system of claim 2, in which the partitioning of the classes with respect to the hold-up degrees is an adaptative partitioning which may vary depending on the segment and direction of travel under consideration, in particular as a function of the lie of the land over which the segment runs and of the corresponding type of road.
4. The system of claim 2, in which the partitioning of the classes with respect to the hold-up degrees is an adaptative partitioning which may vary depending on the increase of the state of congestion of the traffic.
5. The system of claim 2, in which a predetermined, non-ambiguous value ('101') is given to the state value whenever the effective degree of hold-up is indeterminate or non-significant.
6. The system of claim 1, in which the information-collecting means include means for transmitting information concerning the occupancy rate of parking areas attached to reference locations, and the associated state variable in this case is a digital value ('001', '01 0', '011', '100') designating, amongst a plurality of classes of occupancy rates, the class to which the effective occupancy rate of the reference location under consideration belongs.
7. The system of claim 6, in which the occupancy rate is a relative degree (x . C, with x ≦ 1) expressed with respect to the capacity (C) of the parking area.
8. The system of claim 6, in which the partitioning of the classes with respect to the occupancy rates is an adaptative partitioning which may vary depending on the increase of the state of congestion of the parking situation.
9. The system of claim 1, in which means are provided for forcing the value of the state variable to one or several predetermined values ("to be avoided", "closed") which are independent of the state of the traffic.
10. The system of claim 1, in which the running sequence of messages is broadcast by radio by means of a digital data broadcasting method using a subcarrier added to the transmitted signal of a radio broadcast, with the receivers (360) on board the vehicles being radio broadcast receivers fitted with decoders capable of separating out the digital signal from the audio program signal.
11. A system according to claim 1, in which the predetermined criterion on the basis of which the discriminator means act comprises an itinerary formed by a sequence of segments (AB-BC-CD-DE) determined from selection data previously entered by the user, the discriminator means then selecting only those individual digital messages which correspond to the reference locations and/or segments of said itinerary, optionally in conjunction with messages relating to reference locations and/or segments in the vicinity of said itinerary.
12. A method for collecting and broadcasting information concerning vehicle traffic and parking, in particular for car drivers, characterized by the following successive steps:

    (a) describing a zone, in particular a built-up area, by a lattice of segments extending between predetermined pairs of reference locations,

    (b) collecting and centralizing information relating to the state of traffic in said given zone, each individual record in said centralized information corresponding to a respective segment, said information being collected from transmitting and/or receiving beacons co-operating with responders installed on a traffic-sampling subset of vehicles constituting a sample of all of the vehicles constituting the traffic, said traffic-sampling vehicles being provided with means for providing said beacons, via said responders, with information concerning their own progress within said zone, and/or information originating from sensors for distance travelled and/or travel direction, said centralized information further possibly including information originating from magnetic pick-ups used for controlling traffic lights and/or from means for counting vehicles entering and leaving car parks and/or from video cameras and/or information provided by police cars, and

    (c) transforming this centralized information into a series of individual digital messages each constituted by an identifier specifying the segment and the direction of travel over said segment and a state variable representative of the state of the traffic on said segment in said travel direction, expressed as a respective travel time;

    (d) generating a running sequence of messages based on said series of individual digital messages, said running sequence being continuous and cyclic and being constituted by the individual digital messages corresponding to each of the segments under consideration, said sequence being regularly updated as a function of changes in the information as collected;

    (e) broadcasting said running sequence of messages by radio; and

    (f) on board said vehicles: for receiving the running sequence of messages broadcast in this way; selecting those individual digital messages from amongst the set of messages of the running sequence of information thus received that may be of interest to the driver as a function of predetermined selection criteria entered thereto by the driver; and presenting the individual messages selected in this way to the driver.
13. The method of claim 12, in which said state variable is a digital value ('001', '010', '011', '100') designating, amongst a plurality of classes of hold-up degrees ("fluid"; "dense"; "held-up"; "jammed"), the class to which the effective degree of hold-up at a given instant for the segment and direction of travel under consideration belongs.
14. The method of claim 13, in which said hold-up degree is a relative degree (x.t_m, with x ≧ 1) expressed with respect to said travel time (t_m) determined for the segment and direction of travel under consideration upon a situation of total fluidity.
15. The method of claim 13, in which the partitioning of the classes with respect to the hold-up degrees is an adaptative partitioning which may vary depending on the segment and direction of travel under consideration, in particular as a function of the lie of the land over which the segment runs and of the corresponding type of road.
16. The method of claim 13, in which the partitioning of the classes with respect to the hold-up degrees is an adaptative partitioning which may vary depending on the increase of the state of congestion of the traffic.
17. The method of claim 13, in which a predetermined, non-ambiguous value ('101') is given to the state value whenever the effective degree of hold-up is indeterminate or non-significant.
18. The method of claim 12, in which a step is provided which consists in transmitting information concerning the occupancy rate of parking areas attached to reference locations, and the associated state variable in this case is a digital value ('001', '010', '011', '100') designating, amongst a plurality of classes of occupancy rates, the class to which the effective occupancy rate of the reference location under consideration belongs.
19. The method of claim 18, in which the occupancy rate is a relative degree (x . C, with x ≦ 1) expressed with respect to the capacity (C) of the parking area.
20. The method of claim 18, in which the partitioning of the classes with respect to the occupancy rates is an adaptative partitioning which may vary depending on the increase of the state of congestion of the parking situation.
21. The method of claim 12, in which a step is provided which consists in forcing the value of the state variable to one or several predetermined values ("to be avoided", "closed") which are independent of the state of the traffic.

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