EP1262934A2 - Method to detect a traffic situation - Google Patents

Abstract

The method involves the following steps: (a) determination of the positions of motor vehicles (b) determination of the corresponding speeds of vehicles (c) determination of a traffic situation criterion from the captured data (d) determination of a limiting velocity (e) comparison of measured vehicle velocities with the limiting velocity (f) determination of the traffic situation criterion by assignment of a given value to the traffic, i.e. free-flowing, if traffic velocity exceeds the limit velocity.

Description

The invention relates to a method for recording traffic conditions on roads after Preamble of claim 1.

In traffic telematics, traffic conditions are recorded on roads Traffic situation detection systems used by which traffic information to be delivered. For this purpose, traffic data from land vehicles are determined and use this as the basis for recording the traffic situation on the roads. The recorded traffic data can, for example, position and speed one or more land vehicles. These traffic data are through appropriate Sensors determined and evaluated based on certain parameters. Dependent on Certain values (e.g. "undisturbed Traffic "" stalled traffic ", heavy traffic" or "traffic jam") of traffic condition criteria be determined. The determined values of the traffic condition criteria can used for statistical purposes or as the basis for the generation of a Serve traffic status message, which is then available to road users (e.g. traffic reports and travel times via radio or telematic Terminals).

The traffic data can be obtained in different ways. For example can determine the position using the GPS ("Global Positioning System") telematic devices in land vehicles or by stationary cameras. The Speed can be determined by stationary systems or by in Plants carried on land vehicles. There are essentially two Data acquisition systems: the stationary acquisition system ("SES") with permanently installed Sensors (e.g. on a freeway) for measuring traffic flow and "floating Car data method "(" FCD method "), in which telematic devices (so-called" on board units "(OBU)) as mobile sensors in land vehicles, for example one Sample vehicle fleet are provided. The same device with which the Motorists access telematics services, at the same time serve as transmitters for traffic data.

In the known methods for recording the traffic situation, the determined Traffic data evaluated using different algorithms. Essentially these algorithms are based on the fact that a traffic incident is reported when a certain number of land vehicles in a certain area and time interval fall below a specified speed value.

Precise and up-to-date is a prerequisite for many telematics services Knowledge of the traffic situation. However, it has been shown that the known methods for Traffic situation detection does not always provide reliable results. This is true especially when recording the traffic situation on roads that are not crossing Traffic lights too. The state of the art for traffic situation detection in urban road networks only central-side and no terminal-side procedures (FCD procedure).

The invention has for its object in a method for Traffic situation detection of the type mentioned the detection of traffic disruptions to improve.

The invention is based in particular on the task of recognizing To carry out traffic disruptions depending on the respective road network.

The invention is further based in particular on the task of recognizing Improve traffic disruption on intersection-free roads.

According to the invention this object is achieved by the in the characterizing part of Features listed claim 1 solved.

According to the invention, a limit speed is set with which the actual vehicle speed of land vehicles is compared. In A value of a traffic condition criterion then becomes dependent on this comparison determined, exceeding the limit speed as a parameter is used to determine the traffic condition criterion.

Known methods for recording traffic conditions on roads are for national networks, especially optimized for expressways (and motorways) and for example for Congestion detection designed. Rides on expressways that are free of traffic lights and intersections characterized by high speeds. As soon as the speed is sufficient long enough to become sufficiently small, a traffic disruption can be assumed whereby only stopping at service stations, petrol stations or similar must be filtered out. This is the basic idea of detecting disrupted traffic (e.g. traffic jam detection) Expressways using the FCD method.

The invention is based on the knowledge that such methods for use in Conurbations are not suitable. For traffic detection using such FCD procedures is needed in metropolitan areas because of lower traffic flows with the same quality higher equipment levels than on expressways. Because of the frequent stopping in metropolitan areas, e.g. at an intersection or at a traffic light, one is on the Traffic jam detection based on falling below a limit speed is not suitable. ever after the restrictivity of the parameterization, the traffic is erroneously considered to be disturbed or reported undisturbed. The known methods can cause traffic disruptions Do not differentiate undisturbed traffic in metropolitan areas quickly and safely, because Link lengths, duration of red phases in traffic lights, loss of time in Turn maneuvers etc. can vary within wide limits.

The invention is further based on the knowledge that a characteristic of undisturbed Traffic in metropolitan areas exists, which so far has not been able to distinguish between disrupted and undisturbed traffic has been used. This characteristic consists of a (explicitly or implicitly determined) maximum speed, which of all Vehicle types can also be reached, for example those in Germany statutory maximum speed of 50 km / h. In this sense is a Undisturbed city traffic characterized by the fact that a certain Limit speed (e.g. 40 km / h) is not always, but always exceeded becomes.

Surprisingly, tests with real data have shown that the The method according to the invention can be used very well in all road networks, independently whether it is in the supraregional secondary, tertiary or regional area located.

The method according to the invention can be used for local, stationary acquisition (SES) are used in which the observation of land vehicles with cameras or by air observation or similar he follows. In particular, however, is the invention Procedure suitable for FCD procedures, since it with speed profiles of Land vehicles operated.

The procedure is basically by detecting the vehicle position and the Vehicle speed of a single land vehicle feasible. On A single vehicle can find disrupted traffic, for example if it is longer Time from a tractor creeping in front of him, heavily loaded trailers or similar. is hindered. However, the method according to the invention preferably includes this Detect the vehicle positions and the associated vehicle speeds from several land vehicles, the traffic status reports (e.g. "undisturbed Traffic ") depending on several of the detected vehicle positions and several the detected vehicle speeds is determined.

The value of the determined traffic condition criterion can exceed the Limit speed of at least one land vehicle in a particular one local area and / or within a certain time interval. For certain It is important to know traffic reports in which local Range and / or the time interval in which the limit speed is exceeded, thus, for example, a corresponding traffic report to the road users in this local area and / or can be sent in this time interval.

The method according to the invention is preferably used in combination with an FCD method used. The vehicle positions of the land vehicles and the vehicle speeds assigned to the respective land vehicle by in Mobile vehicles with land vehicles are detected. Such sensors are for example known as "on board units" (OBU).

A period of time during which the value of the Traffic condition criterion is maintained even if during this Time period there is no exceeding of the limit speed. This can do that Registration volume from the vehicles can be reduced without loss of quality.

The limit speed that can be specified in the method according to the invention can be determined by first defining a maximum speed and determining the limit speed as a function of this maximum speed. The specified maximum speed can be the respective legally permissible maximum speed and the determination of the limit speed can take place according to a certain mathematical relationship. For example, the limit speed can be determined by the relationship ν _f = αν _H , where ν _{f is} the limit speed, α is a freely selectable control parameter with α <1 and ν _{H is} the specifiable maximum speed. The maximum speed ν _H can depend on the street class and assume different values, for example for residential areas, thoroughfares and federal highways. The control parameter α can then be varied, for example, to take account of certain local conditions.

The predefinable maximum speed can be explicitly specified by as Maximum speed the legally permitted on the respective street class Maximum speed is chosen. This can be permitted by law Top speed using a telematic terminal (OBU) one Land vehicle can be detected. For this purpose, the end device contains a digital card, from which the applicable maximum speed can be found. Furthermore can the specifiable maximum speed also from an application-specific Table are obtained through which road classes and permissible Maximum speeds can be linked. This is particularly advantageous if only the street class can be found on the terminal.

Furthermore, the predeterminable maximum speed can be obtained in that the Land vehicle localized and the predefinable maximum speed set centrally a feedback to the land vehicle.

The predeterminable maximum speed can be determined implicitly by the maximum speed being obtained from the driving data of the land vehicle (s). This estimate can be obtained from a certain relationship within which limits of a speed interval can go. This relationship can be, for example, ν _H = (ν _- + ν ₊ ) / 2, where ν _{H is} the predefinable maximum speed and ν _- and ν _{+ are} the limits of a speed interval [ν _- , ν ₊ ], which is determined by the fact that during a certain time a certain percentage of the regularly repeated speed measurement values lie in this speed interval [ν _- , ν ₊ ].

The determined traffic condition (e.g. "undisturbed traffic") can Road users transmitted by sending a corresponding status message become.

Embodiments of the invention are the subject of the dependent claims.

Embodiments of the invention are below with reference to the associated drawings explained in more detail.

Brief description of the drawings

Fig. 1

shows a block diagram of an embodiment of a method the one for traffic situation detection.

Fig. 2

shows a typical speed profile of a vehicle with undisturbed Traffic in metropolitan areas.

Fig. 3

shows a typical speed profile of a vehicle with a fault Traffic in metropolitan areas.

Fig. 4

shows an application-specific table through which street classes and permissible maximum speeds are linked.

Preferred embodiment of the invention

The exemplary embodiments listed relate to FCD methods in which the land vehicles are equipped with telematic end devices (OBUs). Such OBUs include, among other things, a GPS unit for determining the current vehicle position (x, y) _ist , a speed sensor for determining the current vehicle speed ν _ist , a memory for storing data (eg the current vehicle speed ν _ist and the current vehicle position (x, y) _is ), a transmitter for sending data (eg traffic data) and a receiver for receiving data (eg telematics services). Such terminals are known per se and are therefore not described in detail here.

1 shows the sequence of an exemplary embodiment of a method for recording the traffic situation in a block diagram. First, a certain non-zero limit speed ν _{f is} determined. This is represented by block 10. Several limit speeds ν _{f, 1} , ..., ν _{f, n} (n ∈ N) can be specified, which are assigned to different local areas [x, y] ₁ , ..., [x, y] _n . A specific time interval [t ₁ , t ₂ ] can also be specified, in which this limit speed ν _f or limit speeds ν _{f, 1} , ..., ν _{f, n are} valid, or different such time intervals [t ₁ , t ₂ ] ₁ , ..., [t ₁ , t ₂ ] _n for the different local areas. The limiting speeds ν _{f, 1} , ..., ν _{f, n} can be defined in different ways. It can take place either centrally, for example in a traffic situation recording center, or locally in a land vehicle. Some embodiments of the definition of the limit speeds ν _{f, 1} , ..., ν _{f, n} are described later.

If not already determined in the land vehicle itself, the specified limit speeds ν _{f, 1} , ..., ν _{f, n are} transmitted to the land vehicles equipped with OBUs. This is represented by block 12. The transmission takes place by means of wireless communication. The OBU determines in which local area [x, y] _i (i ∈ [1, ..., n]) the land vehicle is located (block 14) and the associated limit speed ν _{f, i} is determined (block 16 ). The current vehicle speed _is ν is determined (block 18) and with the valid limit velocity ν _{f, i} is compared (block 20). This comparison is repeated with a certain clock frequency (eg 1 Hz).

• Wenn ν_ist größer als ν_f,i ist, wird der Wert des Verkehrszustands-Kriteriums auf "ungestört" gesetzt. Dies ist durch Block 22 dargestellt.
• Wenn ν_ist während einer festgelegten Zeitperiode T (z.B. 20 Sekunden) kleiner als ν_f,i ist, wird der Wert des Verkehrszustands-Kriteriums auf "gestört" gesetzt. Dazu wird zunächst festgestellt, ob ν_ist kleiner als ν_f,i schon während einer längeren Zeitperiode t als T ist (Block 24). Wenn dies nicht der Fall ist ("NO"), dann wird der Wert des Verkehrszustands-Kriteriums auf "ungestört" gehalten (Block 22). Wenn jedoch ν_ist kleiner als ν_f,i während einer längeren Zeitperiode als T bleibt ("YES"), dann wird der Wert des Verkehrszustands-Kriteriums auf "gestört" gesetzt. Dies ist durch Block 26 dargestellt.

This defines a traffic condition criterion, the value of which depends on this comparison, with at least one value "undisturbed" being assigned to the exceeding of the limit speed ν _f . In the exemplary embodiment described, the value of the traffic condition criterion is determined as follows:

• If ν _is greater than ν _{f, i} , the value of the traffic condition criterion is set to "undisturbed". This is represented by block 22.
• If ν _is less than ν _{f, i} during a fixed time period T (eg 20 seconds), the value of the traffic condition criterion is set to "disturbed". For this purpose, it is first determined whether ν _is less than ν _{f, i} has been t for a longer period of time t (block 24). If this is not the case ("NO"), then the value of the traffic condition criterion is kept at "undisturbed" (block 22). However, if ν _is less than ν _{f, i} remains as T for a longer period of time ("YES"), then the value of the traffic condition criterion is set to "disturbed". This is represented by block 26.

The values of the traffic condition criterion then become one Traffic situation detection center transmitted via a wireless communication path. The frequency of this transmission is chosen so that as little as possible Notifications take place. A transmission preferably only takes place at one Change of state of the value of the traffic condition criterion takes place.

In the traffic situation detection center, the traffic data reported by the land vehicles are then evaluated and a traffic status report (for example "undisturbed traffic", "undisturbed traffic during [t ₁ , t ₂ ]", "undisturbed traffic in [x, y] _j ") as a function of the values of the traffic condition criteria and, if applicable, the time interval ([t ₁ , t ₂ ]) and the local area ([x, y] _i ). This will be illustrated with reference to FIGS. 2 and 3. 2 and 3 show the current speed ν _{ist of} a land vehicle as a function of time t. The predetermined maximum speed ν _H and the defined limit speed ν _f are shown by dashed lines. At a certain point in time t _A , the land vehicle exceeds the limit speed ν _f . As a result, the value of the traffic condition criterion is set to the value "undisturbed" and a corresponding message ("telegram") is transmitted to the traffic situation recording center. This is shown by an arrow A.

In the further course of the journey shown in Fig. 2, the limit speed ν _f of the land vehicle is repeatedly undershot, that is, ν _is less than ν _f , but the duration of the undershoot is always shorter than the specified time period T, so that the value of the traffic condition criterion maintains the value "undisturbed" and no message is transmitted to the traffic situation recording center. It is therefore assumed that the traffic is undisturbed, although the speed ν _{ist of} the land vehicle can even assume the value zero. This corresponds, for example, to stopping at a red phase in a traffic light system.

In contrast to this, in the further course of the journey shown in FIG. 3, the limit speed ν _f of the land vehicle falls below the specified time period T (here T = t _C -t _B ). At t _C , the value of the traffic condition criterion is then set to the value "disturbed". Since this causes a change in the value of the traffic condition criterion (from "undisturbed" to "disturbed"), a corresponding message is also transmitted to the traffic situation recording center. This is shown by an arrow C. It is therefore assumed that the traffic is then disrupted.

In einem ersten Beispiel wird die Grenzgeschwindigkeit ν_f dadurch festgelegt, daß zunächst eine Höchstgeschwindigkeit ν_H festgelegt wird und die Grenzgeschwindigkeit ν_f in Abhängigkeit von dieser Höchstgeschwindigkeit ν_H bestimmt wird. Wie unten aufgeführt, kann die festgelegte Höchstgeschwindigkeit ν_H die jeweils gültige gesetzliche Höchstgeschwindigkeit in dem jeweiligen örtlichen Bereich sein. Die Bestimmung der Grenzgeschwindigkeit ν_f erfolgt in Übereinstimmung mit der Gleichung ν_f = αν_H, wobei α ein frei wählbarer Steuerungsparameter mit α<1 ist. Dabei wird die Höchstgeschwindigkeit ν_H von der Straßenklasse abhängen und unterschiedliche Werte beispielsweise für Wohngebiete, Durchgangsstraßen und Bundesstraßen annehmen. Da man davon ausgehen muß, daß die meisten Landfahrzeuge die gesetzliche Höchstgeschwindigkeit nicht überschreiten, wird durch den Steuerungsparameter α die Grenzgeschwindigkeit ν_f gegenüber der Höchstgeschwindigkeit ν_H etwas reduziert.

As already mentioned above, there are various options for determining the limit speed ν _f . Some such possibilities will now be described using examples:

In a first example, the limit speed ν _f is determined by first defining a maximum speed ν _H and determining the limit speed ν _f as a function of this maximum speed ν _H. As stated below, the maximum speed ν _H can be the applicable legal maximum speed in the respective local area. The limit speed ν _f is determined in accordance with the equation ν _f = αν _H , where α is a freely selectable control parameter with α <1. The maximum speed ν _{H will} depend on the street class and assume different values, for example for residential areas, thoroughfares and federal highways. Since it must be assumed that most land vehicles do not exceed the legal maximum speed, the control speed α somewhat reduces the limit speed ν _f compared to the maximum speed ν _H.

The specified maximum speed ν _H can be set explicitly by selecting the maximum speed ν _H that is legally permissible on the respective road class. This legally permissible maximum speed can be recorded using the telematic terminal (OBU) of the land vehicle. For this purpose, the end device contains a digital map from which the applicable maximum speed can be found. Furthermore, the predeterminable maximum speed can also be obtained from an application-specific table, by means of which road classes and permissible maximum speeds are linked. A section of an example of such a table is shown schematically in FIG. 4. 4 shows that the local area [x, y] _{1 of} a federal highway (BAB) with a permissible maximum speed of 130 km / h, the local area [x, y] _{2 of} a federal highway (B) with a permissible maximum speed of 100 km / h and the local area [x, y] _{3 is assigned to} a city street (S) with a permissible maximum speed of 50 km / h.

Furthermore, the predetermined maximum speed ν _{H can} be obtained by locating the land vehicle and defining the top speed centrally, with feedback to the land vehicle. This definition can also be made using tables similar to FIG. 4.

However, the predetermined maximum speed ν _H can also be determined implicitly by the maximum speed ν _{H being} obtained from the driving data of the land vehicle (s) itself by an estimate. This estimate can be obtained from the equation ν _H = (ν _- + ν ₊ ) / 2, where ν _- and ν _{+ are} the limits of a speed interval [ν _- , ν ₊ ] (e.g. [63 km / h, 77 km / h ]), which is determined by the fact that during a certain time t _R (e.g. 10 minutes) a certain percentage p% (e.g. 85%) of the regularly (e.g. every second) repeated speed measurement values lie in this speed interval [ν _- , ν ₊ ] , This type of determination of the maximum speed also provides values which are useful for the method.

In the exemplary embodiments listed here, the traffic condition criterion is two-valued with the values "undisturbed" and "disturbed". However, it should be noted that the traffic condition criterion can of course also have more than two values. For example, several different limit speeds for one and same local area, not only between undisturbed and disturbed traffic, but for example between undisturbed Traffic, sluggish traffic, heavy traffic and traffic jams can be distinguished.

Claims (20)

Process for recording traffic conditions on roads by data acquisition using sensors and data evaluation based on parameters, with the following process steps: (a) detecting the vehicle position ((x, y) _is ) of land vehicles, (b) detecting the vehicle speed (ν _ist ) assigned to the respective land vehicle, (c) determining a traffic condition criterion as a function of the detected vehicle position ((x, y) _ist ) and the detected vehicle speed (ν _ist ), marked by (d) determining a specific, non-zero limit speed (ν _f ), (e) comparison of the detected vehicle speed (ν _ist ) of a land vehicle with the limit speed (ν _f ), and (f) determining a traffic condition criterion in which the exceeding of the limit speed (ν _f ) is associated with a specific value (“undisturbed”). A method according to claim 1, characterized by determining a traffic condition criterion in which the exceeding of the limit speed (ν _f ) in a certain time interval ([t ₁ , t ₂ ]; [t ₁ , t ₂ ] _i ) a certain value (" undisturbed ") is assigned. Method according to Claim 1 or 2, characterized by determining a traffic condition criterion in which the exceeding of the limit speed (ν _f ) in a specific local area ([x, y] _i ) is assigned a specific value ("undisturbed"). A method according to any of claims 1-3, characterized in that ß the vehicle positions ((x, _y) act) and the vehicle velocities (ν _is) are detected by a plurality of land vehicles and traffic state criteria where the exceeding of the speed limit (ν _f ) is assigned to a certain value ("undisturbed") for several of the detected vehicle positions ((x, y) _ist ) and several of the detected vehicle speeds (ν _ist ) are determined. Method according to one of claims 1-4, characterized in that a time period (T) is determined during which said value ("undisturbed") of the traffic condition criterion is maintained even if the time period (T) is not exceeded Limit speed (ν _f ) is present. Method according to one of Claims 1-5, characterized in that the vehicle position ((x, y) _is ) of the land vehicles and the vehicle speed (ν _ist ) assigned to the respective land vehicle are detected by stationary sensors. Method according to one of Claims 1-6, characterized in that the vehicle position ((x, y) _is ) of the land vehicles and the vehicle speeds (ν _ist ) assigned to the respective land vehicle are detected by mobile sensors carried in land vehicles. Method according to one of claims 1-7, characterized in that the limit speed (ν _f ) is determined by the relationship ν _f = αν _H , where α is a freely selectable control parameter with α <1 and ν _{H represents} a specifiable maximum speed. Method according to Claim 8, characterized in that the specifiable maximum speed (ν _H ) represents the maximum speed permitted by law on the respective road class. Method according to Claim 8 or 9, characterized in that the specifiable or legally permissible maximum speed (ν _H ) is recorded with the aid of a telematic terminal (OBU) of a land vehicle. Method according to one of claims 8-10, characterized in that the specifiable or legally permissible maximum speed (ν _H ) is obtained from a table (Fig. 4) by which road classes and permissible maximum speeds are linked. Method according to one of claims 8-11, characterized in that the specifiable or legally permissible maximum speed (ν _H ) is obtained by feedback from a central office. Method according to Claims 8-12, characterized in that the specifiable or legally permissible maximum speed (ν _H ) is obtained from the driving data of a land vehicle by an estimate. A method according to claim 13, characterized in that the estimate of the specifiable or legally permissible maximum speed (ν _H ) is obtained from the relationship ν _H = (ν _- + ν ₊ ) / 2, where ν _- and ν ₊ the limits of a speed interval ([ν _- , ν ₊ ]), which is determined by the fact that for a certain time (t _R ) a certain percentage (p%) of the regularly repeated speed measurements lie in this speed interval ([ν _- , ν ₊ ]). Method according to one of claims 1-14, characterized by sending a traffic condition report ("undisturbed traffic") depending on the value (s) ("undisturbed") of the traffic condition criteria or. Method according to one of claims 2-15, characterized by sending a traffic condition report ("undisturbed traffic during [t ₁ , t ₂ ]") depending on the value (s) ("undisturbed") of the traffic condition criteria or Time interval ([t ₁ , t ₂ ]). Method according to one of claims 3-16, characterized by sending a traffic condition report ("undisturbed traffic in [x, y]") depending on the value (s) ("undisturbed") of the traffic condition criteria or the local area ([x, y]). Use of the method according to one of claims 1-17 for Traffic situation detection on streets that are not intersections. Use of the method according to one of claims 1-17 for Traffic situation detection on streets with prescribed maximum speed. Use of the method according to one of claims 1-17 for Traffic situation detection on streets with traffic lights.

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