DE19738646A1 - Arrangement for distributed traffic state detection - Google Patents

Abstract

The arrangement has a central unit (13) and a number of stations (10), each with at least one detection unit monitoring an area, pref. a section of road (1), and data reception and transmitting units for exchanging data with at least one other station. The stations are arranged within the ranges of wireless data communications paths to form a communications chain longer than an individual range. The central unit combines traffic data sets from at least two stations and transmits the result to at least one other station An Independent claim is also included for a method for distributed traffic state detection.

Description

The invention relates to an apparatus and a method for distributed traffic condition detection, consisting of a A plurality of stations with at least one acquisition unit, a data receiver and a data transmitter in particular those with short range, the stations simultaneously record the traffic condition and a wireless Form data transmission chain.

The ever increasing volume of traffic leads in particular to the limited inner-city traffic areas to a destination conflict between maintaining an economical necessary mobility, the limited infrastructural res resources, safety and environmental sustainability. Therefore there are efforts to address urban traffic problems to defuse suitable traffic management systems. Traffic management systems aim to traffic through law Timely information of road users about the current traffic conditions in terms of time, location and modal relocate.

For the functionality of a traffic management is the most extensive possible determination of the current Traffic condition in the road network is an essential requirement. However, the determination of the traffic condition is, in particular in cities because of the large number of facilities, which are also transmission technology have to be networked, have difficulties.

While the problem of widespread distribution currently traffic information by providing it novel electronic media such as digital broadcasting (DAB) and the Internet for both mobile and stationary Is resolved, the crystallizes here too nationwide traffic data collection as a not yet satisfactorily solved problem.  

The state of the art with regard to the nationwide The following is known about traffic data acquisition: Usually become the traffic identifier describing the traffic condition traffic volume, time gap between vehicles, Occupancy of a detector, instantaneous speed and Vehicle category for the location of the registration device determined. So these are local measurements for no clear conclusion on a route-related Allow traffic conditions. A description of the network state in turn consists of individual route-related Traffic conditions together.

Existing detector loops and other detection facilities serve almost exclusively for data supply of control units for traffic-dependent signaling from nodes. Simultaneous use for the Traffic condition detection often fails because the arrangement tion of the detectors for this is unfavorable that third-party systems considerable difficulties in accessing the detector data have and that the installation of a data transmission system is very complex for detector data.

From document WO 95/14292 it is known that route-related traffic conditions due to a sample of vehicles can be determined their position with a Satelli Determine your own navigation system and traffic conditions descriptive data such as B. the sectionally middle Travel speed over a cellular channel to a Zen transmit trale. This procedure is followed by the following sharing afflicted: it is an on-board equipment required, and the level of equipment must be sufficiently large be. Furthermore, a sufficiently large number of equipments Distribute constant vehicles so evenly that everyone Areas are driven sufficiently often. Have first experiences demonstrated that there is a great deal, especially in urban areas uneven distribution of the equipped vehicle fleet in the Network. This has the consequence that in a central incoming status data have different topicality.  

This leads to an inconsistency in the traffic condition data solution and presentation and can thus ensure the success of the process question rens.

There are also several publications for local surveillance of road sections and the derivation of traffic jam warnings known. DE 41 02 381 describes a traffic jam warning system, in which a plurality of traffic jam sensors along a road is arranged, the assigned when the traffic jam is detected by radio Activate warning indicators. In principle, it is about a system for traffic condition detection, its field of activity however, it is limited locally to the dusty areas is.

The publication DE 42 44 393 describes a traffic measuring and Surveillance system, which by means of Sen sorik for recording the traffic condition over a network is connected to a road processor, which is the main pro processor controls signal lights placed on the roadside so that early information and warning of traffic participant is possible. This solution also aims through Warning of road users on site at each local limited effect and does not give an overall view of the traffic conditions in the network.

From the publication DE 43 41 891 is a highly mobile system for measuring and influencing the flow of traffic on roads known for operation in changing locations. Here are known measurement methods for traffic parameters in a mobile system with implementable route stations, implementable Display units, a control center and a system for data transmission used. Disadvantages of this system are the dimensions and masses of the components that make up a trans port on trucks and sometimes in containers. The Data transmission is controlled by a control center and takes place via above-ground cable connections or via an unspecified radio connection. On the Problems of radio data transmission in built-up areas Areas will not be entered.  

Finally, the publication DE 43 07 486 gives traffic control device that by means of an image capture unit and an image radio device to a still image Traffic control unit transmits. It will also be an opportunity specified, several large crossings using a variety of Monitor video radio devices and this by means of a Radio concentrator over a channel with a centrally arranged neten image recovery unit to connect. It is about again a concept of centrally organized transport data transfer. On the problem of radio transmission in urban areas are not included. Instead of which is proposed that a mobile operator Data transport takes over. The disadvantage here is that the Use of the infrastructure of the service provider running costs caused. Alternatively, the use of company radio is proposed beaten, but in which several users share a channel have to share. There can be mutual interference and bloc cations come, especially when there is traffic are not acceptable.

The invention has for its object a device and a method for distributed traffic condition detection create so that in a simple and inexpensive manner without the use of third-party infrastructure as flat as possible in particular, trouble-free recording of traffic conditions which is achieved in urban road networks. The image of the overall traffic condition should be consistent and in even time intervals or completely available on request be cash.

According to the invention the object is achieved in that the front direction for distributed traffic condition detection from one There are a large number of preferably similar stations, which in turn consists of at least one registration unit, put together a data receiver and a data transmitter. The stations are thus within the mutual reach a wireless data transmission link, preferably ent  along the streets in the network, arranged that they have a data about form a chain.

The station's data receiving unit receives from at least another station, hereinafter called the predecessor station denotes a traffic image encoded in digital data. Furthermore, that of at least one detection unit of the Station identified traffic image in digital data encoded. Both data of the registration unit now available and the data receiving unit become a new data record put together, which is now in coded form the traffic image the surroundings of the station and the predecessor station contains. The Sen unit of the station to at least one further station, in referred to as the successor station. The The successor station then proceeds analogously to the station. Minde decoded at least one station in the data transmission chain the sum of all traffic images encoded in a data set to an overall picture of the distributed traffic condition.

Unlike a system that relies on data delivery from is dependent on vehicles moving in the network a non-moving system regardless of the equipment degree of vehicles and their distribution in the network Stent image of the distributed network-wide traffic condition.

Advantageously, the sequence of the Stations, preferably along streets, one spacious and largely complete, distributed traffic status recording. This is especially true for capturing the Traffic density and the current speed z. B. as a traffic jam criterion of importance because of the inner-city traffic flow due to the large number of intersections and traffic lights is naturally very uneven. When assessing the Traffic conditions in city street networks are e.g. B. the on stagnations in front of red light signal transmitters as long as not from Significance, like traffic in the subsequent green phase can drain completely again. If that is not possible  backwash waves, which are only caused by an extensive recording can be recognized and interpreted can. A critical situation is the traffic jam block crossing of upstream intersections because of this other streets are also affected. This blocking can be advantageous by detection at the drainage sections an intersection. It is obvious that a distributed traffic condition detection at different Cross sections along a route is required. It is known to realize a close-range traffic status detection mainly through the wiring effort for the power supply and especially for data transfer limits are set.

In particular, the problem of data transmission is caused by the Training of the described data transmission chain in front partially solved. The data transmission chain enables light the use of wireless data transmission, preferably radio, with a range that is only a fraction is part of the network length to be covered.

The placement of the sta infrastructure along the streets Data transmission that is used exclusively and free of charge can. Because of the usual line of sight along streets, the data transmission unit can be equipped with a low transmission power can be operated. That is an advance setting for the use of frequency bands used for advantageously free use in industry, Service and medicine are released.

In one of several advantageous embodiments of the Invention offer radio receiving and transmitting units, those according to the Europe-wide DECT standard for cordless Phones work. The DECT standard secures with 120 over transmission channels that are used alternately, one after state of the art today the highest possible exclusivity and Interference immunity of the connection. The connection is established using previously agreed addresses for the station  nen. The range can be up to with the directional receiving antenna to be 5 km.

In one embodiment of the invention, statio in the data transmission chain that are not recorded own equipment. If necessary, these serve to bridge larger distances.

In a further embodiment of the invention, in each Station retrieved the entire distributed traffic image become. A maximum of decentralization is thus achieved. In Advantageously, several institutions such. B. Police, emergency services and transport companies to various the current traffic situation see.

The traffic data acquisition is preferably touched by ineffective, installed above the road surface Sensors such as B. infrared sensors, sound sensors, micro wave sensors, magnetic field sensors, light barriers, reflect xions light barriers and video cameras as well as combinations of these sensors. Can also be used in Road surface laid induction loops.

According to a development of the invention, the Device through the use of solar cells from one to make power supply infrastructure independent and thus in connection with the aforementioned design feature advantageously paint a completely self-sufficient, to create a decentralized traffic registration system.

To be the most cost-effective for solar power supply and to achieve wind-resistant construction, the Power requirements of the stations can be minimized. That happens in a further embodiment of the invention by the control Switched off unneeded modules. For the appraisal Traffic sharing is a cyclical update the distributed traffic condition z. B. at a distance of 5 or 10 minutes is sufficient. A data transfer takes place demented speaking only cyclically, so that in the meantime  the sending unit, the receiving unit and the central unit can be switched off. The shutdown of the central office However, prerequisite is that the registration units continue working independently and their recording results can cache. In this way the Power consumption minimized and the sizing of the solar power supply simplified.

In a further interpretation of the invention, the Zen supplements traleinheit the message stream for status information about the current energy supply. Can the used elec amount of energy not supplied by the solar cells , all units of the Station can be switched off for a longer period of time, so that at least the data transmission is ensured can.

The invention thus represents a device with the following advantages:

• - Flexibility and mobility through wireless data transmission and decentralized way of working,
• - independence from existing infrastructure,
• - Low costs due to uniformity of the stations and Wireless data transmission free of charge,
• - Interference immunity and exclusivity of the data transmission channels and
• - Consistent determination of the distributed traffic condition through stationary registration points.

The invention is intended in the following in exemplary embodiments will be explained with reference to the accompanying drawings.

Show it:

Fig. 1 shows a detail of the device for distributed traffic condition detection;

Fig. 2 shows the structure of a station of the apparatus;

Fig. 3 shows the method according to the exchange of messages between the stations, variant 1;

Fig. 4 shows a schematic structure of the exchanged After, variant 1;

Fig. 5 shows the process according to exchange of messages between the stations, version 2;

Fig. 6 shows a schematic structure of the exchanged After, variant 2;

Fig. 7 shows the process according to the exchange of messages between the stations, Variant 3.

The section shown in Fig. 1 from the device for distributed traffic condition detection shows an exemplary arrangement of individual, preferably similar stations ( 10 ) along a road section ( 1 ) and the data transmission chain, which is formed by individual wireless data transmission lines ( 20 ). A station ( 10 ), preferably at the end of the data transmission path ( 20 ), is not equipped with a detection unit ( 11 ) and supplies the sum of the distributed traffic conditions to an evaluation station ( 13 ).

Fig. 2 illustrates the structure of a station ( 10 ). The central unit ( 16 ) is connected to the detection units ( 11 ), to the receiving unit ( 14 ), the transmitting unit ( 15 ) and an interface ( 18 ). The transmitter unit ( 15 ) and the receiver unit ( 14 ) are connected to an antenna ( 12 ), separate antennas for the transmitter unit ( 15 ) and the receiver unit ( 14 ) are also possible. The station ( 10 ) has a power supply ( 30 ), which preferably works with solar energy. A power distribution unit ( 17 ) allocates the electrical energy to the detection units ( 11 ), the central unit ( 16 ), the receiving unit ( 14 ) and the transmitting unit ( 15 ) depending on the agreed operating mode.

Below with reference to FIG. 3 and FIG. 4, the method for decentralized traffic condition detection for a Liniento topology are explained in detail.

Fig. 3 shows the method of exchanging messages in the data transmission chain, which is via the station ( 10 ) as the initiator of a detection cycle, the stations ( 10 ') and ( 10 '') as transit stations and the station ( 10 ''') as the last Station extends. All stations are addressed via their address. Fig. 4 shows the time sequence of the process according to the message composition. In the presentation, any necessary start, separator and end codes as well as checksums and address codes were dispensed with. The procedure for distributed traffic condition detection is described in detail as follows:

• 1. The station ( 10 ) initiates a detection cycle by sending a request message A [10], which is initiated by an agreed request identifier ( 41 ), to the subsequent station ( 10 ').
• 2. If a station that is not a last station detects a message with a request identifier, this message is only passed on to the neighboring station. In Fig. 3 and Fig. 4 in this respect can be seen that station (10 ') the Anfra genachricht A [10], which consists of the request identifier (41) at least, it receives and the request message A [10] subsequent to the station ( 10 '') sends.
• 3. If a station receives a message with a request ID as a last station, the request ID is replaced by a reply ID. Furthermore, the station detects the local traffic image, encodes it into digital data and transmits the response identifier, its own identifier and the digitally coded traffic image to the penultimate station in the data transmission chain. In Fig. 3 and Fig. 4 can be seen in this regard that station (10 '''), as the last station, the request message A [10], which consists of the request identifier (41) at least from the previous station (10' receives') , the request identifier ( 41 ) is replaced by the response identifier ( 42 ) and the self-recorded and digitally coded local traffic image ( 75 ) including its own identifier ( 74 ) is combined to form the response message D [10 ''']. The reply message D [10 '''] is then sent to the predecessor station ( 10 '').
• 4. If a station that is not a last station receives a response message that is identified on the basis of the response identifier, it compiles a new response message by expanding the received response message with its own identifier and the local traffic image that it has captured and encoded . The extended reply message is then transmitted to the predecessor station. In Fig. 3 and Fig. 4 in this respect can be seen that station (10 '') that do not last station, the response message D [10 '] receives with response ID (42), this about its own identifier (76 ) and the local traffic image ( 77 ) detected and encoded by it is expanded and sent to the predecessor station ( 10 ').
• 5. If the response message which is continuously expanded when passing through individual stations reaches the station which initiated the acquisition cycle, the sum of all traffic images coded in a data record, that is to say the overall image of the distributed traffic state, is available there. This overall image can then be transferred to an evaluation station for evaluation. In Fig. 3 and Fig. 4 can be seen in this regard Lich that the cycle initiating station ( 10 ) the response message D [10 '''+10''+10'], which results from the response identifier ( 42 ), the station identifiers ( 74 , 76 and 78 ) and the coded traffic images ( 75 , 77 , 79 ) of the respective stations, the evaluation station ( 13 ) passes.

In a further embodiment of the invention, there is no distinction between an inquiry and an answer message. Fig. 5 and Fig. 6 illustrate the procedural message exchange. At least one message with the sum of the digitally coded traffic images between the stations at the two ends of the data transmission chain, hereinafter referred to as end stations, circulates in the data transmission chain at predetermined time intervals. A section in the message is reserved for each station, where the local traffic image captured and digitally coded by it is to be stored. When a message is received, each station overwrites the digitally encoded traffic image it has captured in the intended message section and sends the message so modified to its successor station. The message length remains constant. In Fig. 5 and Fig. 6 is in this respect can be seen that Zvi rule the end stations (10 and 10 ''') messages of constant length but with digitally encoded Verkehrsabbildern that in the intended portions (75, 77, 79, 81) change, cure. The end station ( 10 ) has, for example, updated its section ( 75 n) with its traffic image and transmits the message D [10n + 10 '+ 10''+10'''] to the successor station ( 10 '). The station ( 10 ') in turn writes its message section ( 77 ) with the captured and coded traffic image. The message D [10n + 10'n + 10 '' + 10 '''] with the overwritten section ( 77 n) is transmitted to the successor station ( 10 ''), which operates analogously. If the message run ends in one cycle in one and the same end station ( 10 ), i.e. there is a return and a return run per cycle, the overall image of the distributed traffic state advantageously lies in each station ( 10 , 10 ', 10 '', 10 ''') and can be viewed and / or evaluated if necessary.

A further embodiment of the invention enables the treatment of disturbed data transmission links ( 20 ). Disturbances are noticed by the sending station ( 10 ) due to the lack of an agreed receipt. If multiple data transmission attempts fail and a preset time passes without a positive receipt, the station ( 10 ) declares itself to be the new end station and behaves as described above. In addition, a malfunction message is now added to the message to be sent back to the predecessor station, so that the remaining stations ( 10 ) and, if necessary, evaluation stations ( 13 ) connected to the interfaces ( 18 ) via the shortening of the data transmission chain and the incompleteness of the determined distributed traffic state are informed. The position of the disturbed data transmission link can be via a temporary replacement transmission system, e.g. B. radio or fixed network the cut off rest of the data transmission chain can be communicated so that this, now also with a new end station, can start as a second system, the independent work. The data exchange with the rudimentary first system can take place via the replacement transmission medium, which can also be coupled via the interface ( 18 ), until the fault has been rectified. Here, too, the fact that the overall image of the distributed traffic condition is present in each station ( 10 ) has an advantageous effect.

In a further embodiment of the invention, shown in FIG. 7, a predetermined station ( 10 ) queries the other stations ( 10 ', 10 '', 10 ''') of the data transmission chain. If a station ( 10 ', 10 '', 10 ''') recognizes its address in the inquiry message, it sends the local traffic image it has captured and digitally coded back to the querying station ( 10 ). All other non-addressed stations in the data transmission chain to the addressed station pass the request message on the outward route and the response message on the return route without inserting their captured and digitally coded traffic image. In Fig. 7 it can be seen in this regard that the predetermined station ( 10 ) z. B. sends a request message A → 10 ''], addressed to station ( 10 ''), first to station ( 10 '). The unaddressed station ( 10 ') forwards the request message A [→ 10''] to station ( 10 ''). The addressed station ( 10 '') sends the local traffic image it has captured and digitally coded in a reply message D [10 ''] to the querying station ( 10 ) via station ( 10 '). The unaddressed station ( 10 ') passes the reply message D [10''] through to station ( 10 ) without inserting its captured and digitally encoded traffic image.

A further embodiment of the invention consists in that the data transmission chain out in a ring topology leads is. Advantageously, at least one night circles correct with the sum of the digitally coded traffic images  of the individual stations in the ring. Here too lies in everyone Station the distributed overall traffic condition and can possibly be viewed and / or evaluated. The ring topology enables easier handling of data transmission malfunctions, but is not sensibly feasible if e.g. B. only individual routes that are not the starting point lead back, should be monitored.

Claims (15)

1. Device for distributed traffic condition detection with a plurality of stations, which in turn from

• - At least one detection unit for monitoring an area, preferably a road section and
• - A data receiving unit for receiving data at least one other station and
• a data transmission unit for transmitting data to at least one further station and
• - there is a central unit,
  characterized in that
• - The stations are arranged within the at least pairwise mutual range of wireless data transmission lines that they form a data transmission chain of greater length than a single range of a wireless data transmission line, and
• - in at least one station
  • a) at least one detection unit determines a traffic image, encodes it in digital data and supplies the digital data to the central unit, and
  • b) the central unit assigns the digital data supplied by the recording unit to a data record A, and
  • c) the data receiving unit receives at least one traffic image encoded in digital data from the transmitting unit at least one other station and forwards these digital data to the central unit, and
  • d) the central unit assigns the digital data supplied by the data receiving unit to a data record B, and
  • e) the central unit combines the digital data of the data sets A and B into a new data set C and forwards it to the data transmission unit, and
  • f) the data transmission unit transmits the data record C supplied by the central unit to at least one further station.

2. Device for decentralized traffic condition detection according to claim 1, characterized in that it in the Data transmission chain also stations without registration can give at least one in digital data encoded traffic image of at least one station received and this to at least one other station to transfer. 3. Device for decentralized traffic condition detection according to claim 1, characterized in that individual, in a record A, B or C digitally encoded traffic images or the sum of all in a data set B or C encoded traffic images at at least one station from an evaluation station via an interface can be seen. 4. Device for decentralized traffic condition detection according to claim 3, characterized in that the Interface to at least one station an alternative transmission link can be established. 5. Device for decentralized traffic condition detection according to claim 1, characterized in that the data transmission chain open at the ends or to a ring can be closed. 6. Device for decentralized traffic condition detection according to claim 1, characterized in that for recording solution of the traffic image without contact, upper sensors attached half of the road surface, in particular Infrared sensors, sound sensors, ultrasonic sensors, Microwave sensors, magnetic field sensors, light barriers,  Retro-reflective sensors and video cameras as well as Kombina ions from these sensors. 7. Device for decentralized traffic condition detection according to claim 1, characterized in that for recording solution of the traffic image in the road surface or Use induction loops glued to the road be det. 8. Device for decentralized traffic condition detection according to claim 1, characterized in that the current the stations are supplied via solar cells. 9. Device for decentralized traffic condition detection according to claim 1, characterized in that the current saving operation of the stations a power distribution unit the registration units, the central unit, the Receiving unit and the sending unit the electrical Allocates energy depending on the agreed operating mode. 10. A method for decentralized traffic condition detection before preferably using the device according to claim 1, characterized in that a station

• - A traffic image is captured, encoded in digital data and assigned to a data record A and
• - Receives and receives a message in which at least one further traffic image encoded in digital data of at least one further station is contained
• - Assigns the digital data of the received message to a data record B and
• - Combined both data records A and B into a new data record C and
• - Sends the new data record C as a message to at least one other station.

11. The method according to claim 10, characterized in that

• a station initiates a detection cycle with a request phase by sending a request message to another station, and
• - The request message is passed on from one station to the next station of the data transmission chain without adding the data record A until the request message has reached the last station of the data transmission chain, and
• - The last station in the data transmission chain after receiving the request message initiates a response phase by capturing a traffic image, encoding it in digital data, assigning it to a data record C and sending the data record c together with its own identifier as a response message to the predecessor station in the data transmission chain , and
• - Each station during the response phase in the order of the data transmission chain until it reaches exactly the station which initiated the acquisition cycle, forms the data records A, B and C and sends a response message with the content of the data record C, and
• - The acquisition cycle is ended with the arrival of the response message in exactly the station that initiated the acquisition cycle.

12. A method for decentralized traffic condition detection preferably before using the device according to claim 1, characterized in that

• a predetermined station, preferably the first of the data transmission chain, which addresses the remaining stations in the data transmission chain with an inquiry message, and
• an addressed station answers the request message addressed to it by sending out a reply message which is addressed to the requesting station and contains at least the self-recorded local traffic image encoded in digital data, and
• - An unaddressed station in the data transmission chain between the predetermined station and the addressed station forwards messages without adding the self-encoded traffic image encoded in digital data.

13. The method according to claim 10, characterized in that

• the circulating messages contain all or part of the traffic images encoded in digital data of all stations or part of the stations in the data transmission chain, and
• - Each station inserts its data record A into a predetermined, preferably always the same section of the cursing message by overwriting the section data from the previous acquisition cycle, and
• - A detection cycle is started with the sending of a message from a station preferably located at the end of the data transmission chain and is finished with the return of the circulating message in the same station.

14. The method according to claim 13, characterized in that

• - A detection cycle is started with the sending of a message from both stations at the end of the data transmission chain and with the return of the two circulating messages in the opposite station at the end of the data transmission chain is ended, and
• - the two messages circulate at least temporarily at the same time in the data transmission chain, and
• - The two messages have an opposite direction of movement in the data transmission chain.

15. The method according to claim 13, characterized in that at least one message in the data transfer at the same time chain.