EP0384794A1 - 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 for collecting and disseminating information on the circulation and parking of transport vehicles, intended in particular for motorists.

It is common practice 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 an agglomeration.

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.

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.

Mention may in particular be made of the system developed by Siemens AG with the assistance of the University of Berlin and of Robert Bosch GmbH under the name Aliscout , which is based on a system of bidirectional data exchange by infrared 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, orientation compass, etc.) and a transceiver operating as an answering machine.

When approaching a crossroads, and upon 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.

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 the possibility of reuse 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 host center. The increase in the number of crossroad beacons therefore requires a correlative 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 equipment emitting infrared receiver / receiver 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 simply wish 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 an automatic guidance of which they are not masters.

The invention aims to remedy the drawbacks of the above system, by proposing a system for collecting and disseminating information which:
- for the collection of information, uses, 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 the regulation of circulation by synchronization of traffic lights, and
- for the dissemination of information, makes it possible to offer a wide audience of users the dissemination of information by 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 providing information of interest to the driver given his route, for example information relating to ten or fifteen sections or characteristic places.

More specifically, the system of the invention comprises, for this purpose:
means of collecting information, for collecting and centralizing a set of information relating to the state of traffic in a given area, in particular an urban area, each of the items of information in this set of information corresponding to a section between two predetermined characteristic places,
means for transforming this set of information into a series of elementary digital information each consisting of a section identifier, comprising a parameter for indicating the direction of traffic on this section and a state variable representative of the traffic status of this section in said traffic direction;
means for developing, from this series of digital information, a scrolling sequence of information, continuous and cyclic, consisting of elementary digital information from all the sections considered, this sequence being regularly updated as a function of evolution of the information collected;
means for broadcasting this scrolling sequence of information by radio; and
- on board said vehicles: means for receiving the scrolling sequence of information thus broadcast; means discriminators to select, from among all of the elementary information, that likely to interest the driver according to a predetermined criterion introduced by the latter; and means for presenting the driver with the elementary information thus discriminated.

Very advantageously, the means of collecting information comprise transmitting and / or receiving beacons cooperating with answering machines installed on board a subset of witness vehicles constituting a sample of all the vehicles participating in the traffic, these vehicles -witches being provided with means for the responders to return to the beacons, information on their progress in said zone.

These means of collecting information can for example be constituted by the aforementioned Aliscout system, namely a system in which the means for returning to the beacons information on the progress of the witness vehicles in said zone include distance traveled sensors and / or orientation whose information is returned by the responders to the beacons when they emit an interrogation signal.

However, in the latter 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 among the vehicles circulating intensive (taxis, buses, couriers, public service vehicles, etc.).

If such an information collection system is used, 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,
- either use only a simplified system, with a unidirectional link from the beacon to the server center and without a decoding and display system for 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. teme 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 broadcasting receivers equipped with a decoder providing separation of digital signal information from audio program signal.

One can in particular use for this purpose the RDS system ( Radio Data System ) for the broadcasting of digital data by radio in frequency modulation, and whose specifications have been defined by the European Radiocommunication Union, these specifications being notably 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" making it possible to transmit 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 suffices only to code in an appropriate manner the signal on transmission) 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.

According to other advantageous characteristics:
- the means of collecting information include means for transmitting indications relating to the state of occupation of parking areas attached to characteristic places;
the predetermined criterion according to which the discriminating means act comprises a route formed by a sequence of sections determined from selection data previously entered by the user, the discriminating means then selecting only the elementary digital information corresponding to the sections and / or characteristic places of this route and, possibly, to sections and / or characteristic places close to this route.

• La figure 1 est un schéma synoptique du système de l'invention, montrant les différentes fonctions mises en oeuvre.
• La figure 2 est une représentation d'un itinéraire choisi par le conducteur ainsi que des lieux caractéristiques environnants de celui-ci.

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 with respect 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 numerics representative of the state of traffic in each characteristic place of the agglomeration.

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 the characteristic places and the sections is carried out so as to achieve a complete grid of the agglomeration, while making it possible to describe almost all the possible routes in a simple and unequivocal 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.).

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 slowdown 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 by the same amount during a phase of return to a normal situation. .

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 “fluid” class;
- '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 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.

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 occupancy between 0,2.C and 0,7.C;
- '011' for an effective occupancy between 0.77C and 0.9.C;
- '100' for an effective occupation 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.

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 section 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.

We then provide additional values for the state variable, for example:
- '110' for “to avoid”; or
- '111' for “prohibited”.

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.

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 together (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. meration (as well as characteristic places thereof corresponding to the parking areas whose occupancy 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 will be able to code the elementary digital information on 16 bits which, once grouped together, will form a segment of 16 000 bits. If we consider that 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.

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 from a recording control unit (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 encoder (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 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 criteria introduced. (s) by the latter by means of a keyboard 250.

This selects the relevant messages and restores only those 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 ' that is to say, 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.

It is possible to provide a number of variants or improvements:
- the storage of several pre-established 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 returned at the same time as the route itself;
- isolated interrogation of a given section or of a given parking area.

Furthermore, it is possible to provide for dissemination not only of information relating to the sections of the chosen route (ABCDE, in the example illustrated), but also of 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 (6)

1. A system for collecting and disseminating information on the circulation and parking of transport vehicles, in particular for motorists, characterized in that it comprises:
- Information collection means (100) for collecting and centralizing a set of information relating to the state of traffic in a given area, in particular an urban area, each of the items of information in this set of information corresponding to a section between two predetermined characteristic places,
- Means (210) for transforming this set of information into a series of elementary digital information each consisting of:
· A section identifier and direction of traffic on this section, and
· A state variable representative of the traffic state of this section in said traffic direction;
- Means (220) for developing, from this series of digital information, a scrolling sequence of information, continuous and cyclic, consisting of elementary digital information from all the sections considered, this sequence being regularly updated as a function the evolution of the information collected;
- means (330, 340, 350) for broadcasting this scrolling sequence of information by radio; and
- on board said vehicles:
· Means (360) for receiving the scrolling sequence of information thus broadcast,
Discriminating means (240) for selecting, from among all of the elementary information, that likely to interest the driver according to a predetermined criterion introduced by the latter, and
· Means for presenting the driver with the elementary information thus discriminated. 2. The system of claim 1, in which the means for collecting information comprise transmitting and / or receiving beacons (120) cooperating with answering machines (115) installed on board a subset of witness vehicles constituting a sample of all the vehicles participating in traffic, these witness vehicles being provided with means for the responders to return to the beacons, information on their progress in said zone. 3. The system of claim 2, in which the means for returning the information on the progress of the control vehicles in said zone to the beacons include distance traveled (113) and / or orientation (112) sensors, the information of which are returned by the responders to the beacons when they emit an interrogation signal. The system of claim 1, wherein the scrolling sequence of information is broadcast over the air by a method of broadcasting sub-carrier digital data added to a broadcast transmission signal, the receivers (360) on board vehicles being broadcast receivers equipped with a decoder ensuring the separation of digital signal information from the audio program signal. 5. The system of claim 1, wherein the information gathering means comprises means for transmitting indications relating to the state of occupation of parking areas attached to characteristic places. 6. The system of claim 1 or claim 5, in which the predetermined criterion according to which the discriminating means act comprises a route formed by a sequence of sections (AB-BC-CD-DE) determined from data previously introduced by the user, the discriminating means then selecting only the elementary digital information corresponding to the sections and / or places characteristics of this route and, possibly, to sections and / or characteristic places neighboring this route.

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