EP0880120B1 - Method for detecting and signalling traffic position data - Google Patents

Description

The invention relates to a method for detection and Reporting traffic situation data of a road network by means of sampling vehicles, according to the method in each sampling vehicle at predeterminable times an automatic position determination is carried out and dependent on associated traffic situation data be recorded and reported.

Conventionally, traffic situation data, e.g. for an automobile road network, determined by infrastructure. For example are the traffic situation data of measuring instruments in the form of Induction loops detected along the considered road network and relayed via signal cables to a central office where they evaluated by means of special hardware and software and in particular investigated for occurred incidents of traffic become. These infrastructure-based procedures are comparative consuming and also allow the detection of accidents only if their effects affect at least one Point of the road network show.

To improve this conventional approach are already Method of the type mentioned, without trackside infrastructure by capturing and Reporting the traffic situation data of so-called sampling vehicles, also referred to as "floating cars", which are suitable for this purpose and the considered road network traveled. By the name sample vehicle is intended be expressed that it is sufficient, a comparatively small proportion of all vehicles using the road network in this way for collecting the traffic situation data, i. from track-related, to assess the traffic situation in the Road network relevant data, as such sampling vehicles interpreted. The message of the traffic situation data is preferably via a radio communication link, e.g. a mobile network, to a stationary center and / or others Vehicles. A known difficulty of these methods is in that usually during each traffic situation reporting process transferred amount of data related to the capacity existing radio networks is relatively large, so that there are radio network overloads can come. In addition, the processing requires the large amounts of data corresponding computing effort.

To remedy this situation, in the published patent application DE 195 21 919 A1 a method of the type mentioned, proposed which reduces the amount of data to be transferred shall be that those recorded by the relevant sampling vehicle, traffic-related vehicle and position data of one or multiple vehicle and position data classes that correspond to a particular correspond to typical vehicle behavior and the assigned class as the current vehicle behavior pattern with the position data for a respective reporting process is transmitted, especially to a traffic computer. So that should be achieved that in a respective reporting process not the transfer complete data records of the vehicle and position data but only the assigned vehicle behavior pattern in the form of an identifier, which refers to the current Class affiliation, along with the positional data of the sample vehicle.

Another method for traffic location detection means a sample vehicle fleet with data volume reducing Measures is described in the published patent application DE 195 17 309 A1. In this procedure, the vehicles are in exchange groups subdivided, where vehicles of a respective exchange group under itself vehicle data, i. Data about the environmental and / or operating condition of the vehicle, and position data, i.e. Data about the position of the respective vehicle too at any given time. A selected vehicle Each exchange group transmits the reconditioned vehicles and vehicles Position data of a replacement group to a central computer, wherein the position data regularly after covering a certain distance and / or after a predetermined Time span are transmitted. For the vehicle data can be provided be to specify tolerance values and this together with the To transmit positional data only if a part of them exceeds the specified tolerance values.

WO 95/14292 discloses a comprehensive, centralized Method of data collection, processing and storage using a lot of sampling vehicles. there be in a sample vehicle on sections of a Road network related data stored together with the road network, and a traffic data reporting process is triggered if data currently collected in the sample vehicle is a Deviation by more than a respective, specifiable threshold is detected from the stored data.

The invention is the provision as a technical problem a method of the type mentioned, with the Traffic situation data reliable and with comparatively To raise little effort and relatively easy different driving conditions of sampling vehicles Account can be taken.

The invention solves this problem by providing a Method with the features of claim 1. In this method becomes the considered road network in the sample vehicles together with journey time data for the sections of the road network expected travel time, e.g. as digital Data in an electronic memory. After each one automatic position detection, e.g. at certain intervals or upon reaching certain locations of the road network or upon occurrence of one or more other predetermined triggering criteria can be triggered, then the determined, actual Position with the stored on the basis Teilstrekken travel time data expected position and / or the actual Travel time with the stored on the basis of the distance traveled trip duration data compared to the expected journey duration. The actual travel time is determined as the time span between the current and the previous position determination process, while the expected journey time directly from the stored travel duration data is readable. The expected Position is starting from that from the previous one Position determination process known vehicle position thereby determines that the point of the subsequently traveled route network sub-section visited on the basis of the stored route network is, for the stored, the expected travel duration the time span until the current position determination process equivalent. A traffic data reporting process then becomes at most then triggered when the actual position and / or journey time by more than one, specifiable Threshold deviates from the expected position or travel time. In this case, the threshold value for the determined position or Driving time deviations not immutable, but as given a variable that is at least determined by the variance of Vehicle speed depends.

As a result, this procedure avoids traffic data reporting procedures, as long as the sample vehicle with a through the tolerance specified in the threshold for the individual Sections of the route network stored travel duration data emotional. Conveniently, the stored correspond Partial journey duration data of a trouble-free traffic situation. The absence of traffic situation reporting by a respective sampling vehicle is thus for any headquarters and / or for the other vehicles driving the route network an indication of a trouble-free traffic situation. That for detection of traffic jams unnecessary transferring distance-related Data from a respective sample vehicle in traffic jam-free Situations is avoided by this method Overall, the amount of data to be transferred is considerable reduced, so that the data communication easily on one usual mobile communication path, e.g. a digital one Radiotelephone network, can be done. Results on one of one Sampling vehicle traveled segment a traffic incident, e.g. a jam, so this is reliable in a next position determination this vehicle detected by then a strong Deviation of the actual from the stored according to the Teilstrecken-driving time data expected position or a corresponding significant deviation to achieve a certain Waypoint required travel time of the according to the stored travel duration data expected to travel time becomes. This then leads, possibly linked to more Tripping conditions, to trigger a corresponding message the current traffic situation data, which is stored by the expected traffic situation deviating traffic situation, i. the traffic congestion, characterize. Where is the threshold not for the determined position or travel time deviations invariable, but given as a variable that depends at least on the variance of the vehicle speed. This allows relatively different driving conditions Be taken into account by e.g. typically stronger fluctuating vehicle speed, a traffic data reporting process only with a larger deviation of the actual Position or travel time from the expected position or Driving time than with lower speed fluctuations is triggered. By appropriately variable selection of the threshold value systematic deviations can also be taken into account, which may be due, for example, to the fact that for a more sporty driver tends to be lower than that expected driving time and vice versa for a more cautious Driver higher than expected driving times result.

In a further developed according to claim 2 method is for the individual sections of the route network expected, stored Driving time not fixed, but given as a variable, which depends at least on the time and / or the date. This can easily take into account the fact that, at least on certain sections, to certain Times for daily, weekly and / or seasonally fluctuating traffic density and / or road conditions different driving times are to be expected.

In a further developed according to claim 3 method are reported Traffic situation data pointing to a specific traffic jam only from a receiving headquarters or receiving vehicles other than actual traffic jams interprets if there are more than one traffic data message in this regard of the sample vehicle (s) be received within a predetermined confirmation time. This provides protection against accidental misreporting or pre fake traffic disruption messages by an untypically driven Sample vehicles.

In a further developed according to claim 4 method is provided if there is a permanent deviation from the actual from the expected journey time over a predefinable, longer Observation period, the actual journey time for the respective leg of the road network as new expected Save travel time for all vehicles. To this Way can also for road network sections, for the so far no the expected journey duration is present for the first time become. In addition, if necessary, new sections, the not yet part of the saved road network are the first time you drive through a sample vehicle recorded and along with the required travel time than the expected Driving time are stored for the first time, making the stored road network is extended accordingly.

Fig. 1

ein schematisches Blockdiagramm einer in einem jeweiligen Stichprobenfahrzeug untergebrachten Vorrichtung zur Erfassung und Meldung von Verkehrslagedaten und

Fig. 2

ein Flußdiagramm des Grobverlaufs eines von der Vorrichtung gemäß Fig. 1 durchführbaren Verfahrens zur Erfassung und Meldung von Verkehrslagedaten.

An advantageous embodiment of the invention is illustrated in the drawings and will be described below. Hereby show:

Fig. 1

a schematic block diagram of an accommodated in a respective sampling vehicle device for detecting and reporting traffic situation data and

Fig. 2

a flowchart of the coarse course of a feasible from the apparatus of FIG. 1 method for detecting and reporting traffic situation data.

The device shown in Fig. 1 is in a respective Sample vehicle installed, with the distance-related data, i.e. Traffic situation data, without trackside infrastructure measures can be recorded and reported. The device has a conventional hardware structure, the vehicle-side On-board computer 1 comprises, to which a road network memory 2, a vehicle position measuring device in the form of a GPS receiver 3 or alternatively another position determining device and a radiotelephone 4 are connected. About the GPS receiver 3, the on-board computer 1 is able in the usual way at desired times the vehicle position automatically determine. The on-board computer 1 determines the vehicle position within a road network accessible by the vehicle, e.g. one Motorway network, this navigable road network in digital Form retrievable stored in the road network memory 2. The Radiotelephone 4 serves as a vehicle-side communication terminal for communication of the on-board computer 1 with a not shown, stationary headquarters. Specifically, the communication terminal 4 e.g. a D-network telephone or a so-called Modakom unit his.

To carry out the characteristic described below Process are compared to conventional system designs the on-board computer 1 and the road network memory 2 in particular as regards the implemented software or the stored Data modified in a way that is obvious to those skilled in the art the following explanation of the feasible by this device Method readily yields and therefore none here requires more detailed explanation. In particular, the road network memory includes 2 not only the data on the structure of the passable Road network including distance information between individual road signs, but also driving time data, with those of a respective section of the road network a for their driving normally, i. without traffic congestion, expected driving time is assigned. This the respective route network sub-section individually assigned information For example, the expected driving time can be determined empirically and in advance both to the existing Sampling vehicles as well as a possible stationary Central and the rest, the road network driving vehicles to provide. The expected journey time does not need to be invariable for a particular leg, fixed size, but it is preferred as at least one of the time and / or the date assigned dependent variable. This can be taken into account that the expected for a particular leg route duration generally fluctuates both on a daily basis and depends on whether the trip is on a weekday or on a weekend and / or winter or summer road conditions it is to be reckoned with, which in each case appropriate effects on the average vehicle speed and thus the expected travel time has.

FIG. 2 is a schematic flow diagram roughly illustrating the main flow of the method of detecting and reporting traffic situation data by a respective sampling vehicle that can be performed by the apparatus of FIG. 1. After the start of the process 10, the required initial conditions are determined in an initialization step 11. This involves the start of a time counter which continuously detects the time t starting with the start time t _o = 0. In addition, the initial position x _o = x (0) of the relevant sampling vehicle is determined by a corresponding initial position determination. Furthermore, a time interval t _{p is} specified, after the expiry of which a new position determination is to be carried out. Alternatively, the position determinations carried out at predeterminable times can also be made in each case when the vehicle has reached certain road network points, for example the end point of a respective road network sub-section, which is assigned a specific, expected driving time. As a further alternative, a triggering of position determination operations may be provided by certain events, especially after a strong braking operation with subsequent actuation of the hazard warning lights as suspected jam end. In this alternative, information about the triggering event is then transmitted in addition to the determined position. In addition, in all alternatives, an event counter having a count i which detects the number of position determinations made is initially set to zero.

Subsequently, it is continuously queried (step 12) whether the predetermined time span t _{p has} elapsed since the time t _{i of} the initialization or of a preceding position determination, ie whether t≥t _i + t _p holds. Only when this condition is met, in the next step 13, is the position determination event count i increased by one, and then the vehicle position x _i = (t) determined at that time. In the relevant position determination step 14, the associated position determination time t _i is then set to the corresponding time value t of the time counter, and the distance traveled since the preceding position determination or initialization s _i = x _i -x _i-1 is calculated as the difference between the currently determined vehicle position x _i and the previously determined vehicle position x _i-1 calculated. In addition, the on-board computer 1 determines, as a function f (x _i-1 , t _p ) of the last measured position x _i-1 and the elapsed time t _p, that distance w _i , starting from the last measured vehicle position x _i-1 from the vehicle is to be expected during the time elapsed in the meantime t _p on the basis of the stored for the relevant part of the traveled route network, expected driving time in trouble-free traffic as covered by the vehicle distance. It is understood that both the actual distance s _i and the expected distance w _{i are} not to be understood as pure distance indications, but additionally contain the information about the associated route network sub-section, which was traveled by the vehicle since the previous position determination. By way of example, the measured distances s _i and the determined, expected distance w _i are to be regarded as different from one another, even though they have the same distances, but relate to path network sections extending in different directions.

In addition, in the position determining step 14, a threshold value is defined in the form of a percentage deviation amount ds _i by which the actual distance s _i may deviate from the determined, expected distance w _i , without this leading to the triggering of a traffic situation data reporting process. Preferably, this deviation amount ds _{i is} not invariable, but redefined for each positioning operation as a variable amount that depends in a predetermined manner on vehicle condition and / or vehicle environment parameters. Specifically, the allowable amount of deviation ds _{i is set} as a function of the variance in the instantaneous speed of the sampled vehicle so that it can be set to a higher value than, for example, slower vehicle speed than less speed variations, unnecessarily frequent traffic-situation reporting with temporarily greater variations in vehicle speed to avoid.

In a subsequent query step 15, the on-board computer 1 determines whether the percentage deviation of the difference between the actually traveled distance s _i and the expected distance w _i determined for the traveled section has exceeded the predetermined deviation amount ds _i . If this is not the case, a message of traffic situation data is omitted and the process returns before the inquiry step 12, after which a new position determination event is awaited. If, on the other hand, the permissible, predefined deviation amount ds _{i is} exceeded, the on-board computer 1 evaluates this as a release of a traffic position data reporting process (step 16). Depending on the application, the actual triggering of the relevant reporting process can be linked to other conditions, for example, whether the aboard computer 1 an abrupt braking operation or setting the hazard warning lights is observed, which may indicate an incipient traffic jam and therefore the automatic triggering of a traffic situation data reporting and / or whether a fuel cap or a door of the vehicle is opened, indicating a driver-initiated stop, which is not due to the traffic situation and therefore does not require the triggering of a traffic situation data reporting process.

Regardless of whether in the relevant method step 16, a traffic data reporting process is already triggered due to the exceeding of the specified deviation amount ds _i or only on satisfaction of other conditions are required by the present event discrete method less data transfer operations on the mobile communication path 5, what their respective load and the associated cost significantly compared to the aforementioned conventional approaches significantly reduced. After the completion of the reporting process, a cycle of the cycle is completed when the cycle end 17 is reached, and the process returns to the query step 12 for a new cycle, as long as no system shutdown has occurred. The method shown in Figure 2 in its rough sequence can also be further refined as needed. Thus, for example, the reliability of the traffic situation message can be increased by an individually adjustable factor, which constantly compares the actual with the determined, expected driving time from the start of the journey, ie from the initialization time t ₀ , taking into account systematic deviations. Such deviations may, for example, be such that for a sample vehicle occupied by a sporty driver, the actual driving time tends to be shorter than the expected driving time, whereas for a more cautious driver, the actual driving time tends to be longer than the expected driving time.

The after triggering of a corresponding message process in the step 16 from the on-board computer 1 via the communication terminal 4 and the Mobile radio link 5 reported traffic situation data are sent to the stationary headquarters and / or directly as broadcast to all or to certain, e.g. those near the sending sample vehicle transmitted vehicles. Receiver side can. the reported traffic situation data then from the central office or the Notified vehicles evaluated in the desired manner become. The evaluation may e.g. as protection against unique, accidental Failure messages include the measure that one of a certain traffic situation reporting process reported traffic disruption is only considered as such if it is within one certain, specifiable observation period by a traffic data message same content is confirmed, the a later positioning of the same or another Sampling vehicle requires. Preferably is a confirmation provided, the same messages from requires multiple sampling vehicles to avoid traffic jams by a single, inappropriately driven sample vehicle to avoid.

As a further advantageous evaluation measure can for the headquarters and / or the individual vehicles the ability to be provided that if repeated over a long period of time identical traffic position data messages are received, the a permanent deviation of the actual journey time from the stored, expected journey time for the concerned Partial route signal this fact as an indication of a for this section newly resulting, expected travel time is valued. The head office and / or the vehicles involved in this case, override those for the relevant leg previously stored, expected journey time with the transmitted by the traffic data messages, actual Travel time as new expected travel time. With this Measure, it is also possible to split sections of the stored Road network, which so far still no expected journey time was assigned, for the first time with such an expected Travel time to occupy. In this way, if necessary, all Travel time data previously stored without this data Road network during ongoing operation of the or the sample vehicles be assigned, resulting in an empirical preliminary determination the sub-route-related travel time may be unnecessary. Even further in this way even so far not included in the stored path network sections of a sample vehicle driving on it together with associated Duration of travel are reported, so that in the headquarters and / or the other vehicles stored route networks around this section together with associated, expected driving time extended can be.

Claims (4)

1. Method of detecting and reporting data pertaining to traffic conditions on a road network by means of a respective probe vehicle, whereby

   one or more criteria triggering a position detection routine are predefined and, whenever a trigger criterion occurs in the respective probe vehicle, an automatic position detection routine is run, on the basis of which .associated data about traffic conditions is detected and reported,

   the road network is stored in the respective probe vehicle together with travel time data about the anticipated travel time for the part sections of the road network,

   once the actual position (x_i) has been automatically detected, the road network-part section covered since the preceding position detection routine,and the associated actual travel time (t_p) are detected, the anticipated position (w_i+w_i-1) for the actual travel time and/or the anticipated travel time for the actual position are determined on the basis of the stored part sections-travel time data, and the actual position is compared with the anticipated position and/or the actual travel time is compared with the anticipated travel time and a traffic status reporting routine is triggered at most if the actual position and/or travel time deviates from the anticipated position or travel time by more than a respective pre-settable threshold value, and

   the threshold value (ds_i) is pre-set as a variable dependent on at least the variance of the instantaneous vehicle speed.
2. Method as claimed in claim 1, further
   characterised in that
   the stored, anticipated travel time for a respective road network-part section is pre-set as a variable dependent on at least the time or date.
3. Method as claimed in claim 1 or 2, further
   characterised in that
   a traffic disruption message contained in a respective traffic status report is not evaluated as being a traffic disruption at the receiver end unless at least one other traffic status report containing the same information relating to it is received within a pre-settable confirmation period, transmitted in particular from another probe vehicle.
4. Method as claimed in one of claims 1 to 3, further
   characterised in that
   if traffic status reports containing the same information about a respective part section are received over and above a pre-settable observation time indicating a persistent deviation of the actual travel time.from the stored anticipated travel time, the reported actual travel time is stored as a new anticipated travel time for the relevant part section.

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