WO2019072879A1

WO2019072879A1 - Method and device for ascertaining a friction value of a roadway

Info

Publication number: WO2019072879A1
Application number: PCT/EP2018/077532
Authority: WO
Inventors: Simon GEISLER; Christian Lellmann
Original assignee: Robert Bosch Gmbh
Priority date: 2017-10-13
Filing date: 2018-10-10
Publication date: 2019-04-18
Also published as: DE102017218386A1

Abstract

The invention relates to a method for ascertaining a friction value (μ) of a roadway. For this purpose, a data set (16) of street condition data (14) of a winter service (50) and/or a street cleaning service (50) is provided, wherein the street condition data (14) correlates to a surface quality of the roadway. Furthermore, at least one component of the street condition data (14) is assigned to at least one position (s) of the roadway, and at least the component of the street condition data (14) is assigned to at least one point in time (t) at which the component of the street condition data (14) is detected. Furthermore, at least one friction value (μ) of the roadway is ascertained at the at least one position (s) of the roadway and at the at least one point in time (t) on the basis of at least the component of the street condition data (14).

Description

Description title

Method and device for determining a coefficient of friction of a roadway Area of the invention

The present invention relates generally to the field of determining friction coefficients of a roadway. In particular, the invention relates to a method for determining a coefficient of friction of a road and / or a method for creating a friction coefficient map. Furthermore, the invention relates to a device, in particular a data processing device, for determining a

Coefficient of friction of a roadway.

State of the art

Frictional coefficients for lanes, such as roads, parking lots, runways and / or airport runways, are often determined and / or measured based on a direct and active coefficient of friction measurement. To active

Friction value measurement are usually used special measuring vehicles with a Reibwertmesstechnik. Examples of such measuring vehicles are the so-called "Surface Friction Tester" and the "Sideway-force Coefficient Routine Investigation Machine" in which Reibmesswerte the roadway are determined based on a force measurement. For example, the measuring vehicle may have a three-wheeled vehicle trailer with the third wheel in the physical boundary area, i. until the tire stops, can be braked. About the required braking force and / or the necessary braking torque can be the friction force and determine with the help of the known normal force of the coefficient of friction between the road and the third wheel. Alternatively, the frictional force can be determined, for example, by a lateral force of a fifth wheel inclined at about 20 ° to the direction of travel. Also in this case, the coefficient of friction can be determined by knowing the normal force.

However, such measuring methods can not be used without great effort in production vehicles because of the elaborate measuring technology used therein. Disclosure of the invention

With embodiments of the invention, coefficients of friction of a roadway can advantageously be determined reliably, quickly and with high accuracy.

One aspect of the invention relates to a method for determining a coefficient of friction of a roadway and / or a coefficient of friction between a vehicle, such as a tire of the vehicle, and the roadway. The coefficient of friction may denote a coefficient of friction between the roadway and the vehicle. The roadway may refer to a road of a road network, a parking lot, a runway, a runway and / or any other vehicle drivable area. The method is characterized in particular by the following steps:

Providing a record of road condition data of a

Winter service and / or a street cleaning service, the

Road condition data correlate with a road surface condition;

Associating at least a part of the road condition data with at least one

Position of the roadway;

Associating at least the part of the road condition data with at least one

Time at which the part of the road condition data is recorded; and

- Determining at least one coefficient of friction of the roadway at least one

Position of the roadway and at least one time based on and / or using at least the part of

Road condition data.

Generally, the winter service and / or the street cleaning service may designate a road service. The winter service may include, for example, one or more snow clearance vehicles for sprinkling salt and / or gravel on the roadway. Alternatively or additionally, the winter service one or more

Include clearing vehicles for clearing and / or removing snow on the road. Similarly, the street cleaning service may include one or more

Street cleaning vehicles include, which serve for cleaning the roadway, such as by means of water and / or by means of a sweeper.

The road condition data may be from the winter service and / or the

Street cleaning service, for example, be provided via a server. Alternatively or additionally, the road condition data may be provided by at least one clearance vehicle and / or at least one road cleaning vehicle, such as via a suitable data communication interface. The road condition data may in particular describe the surface condition of the roadway, a condition of the roadway and / or a condition of a surface, such as a road surface. For example, the road condition data may indicate at which position and / or in which portion of the roadway the roadway has been cleaned and / or at which position salt has been scattered on the roadway. Also, the

Road condition data indicate at what position and / or in which section of the road snow has been cleared. Also, the

Road condition data include time information and indicate, for example, when was cleared on the road snow and / or when salted. Furthermore, the road condition data can also

Information regarding a type of used clearing vehicle and / or road cleaning vehicle include. Also, information regarding a salt type used, a salt amount, a salt amount scattered per unit time and / or area unit, an amount of water used per unit time and / or unit area, or the like may include.

According to the invention, at least a part of the road condition data can be assigned to at least one position and / or to a section of the roadway. Further, the part of the road condition data is assigned to at least one time point at which the part of the road condition data was acquired. The time may also designate a period of time within which the road condition data has been recorded and / or determined. In other words, the road condition data can be referenced in position and time. Based on and / or using the portion of the road condition data, the coefficient of friction of the roadway at the at least one position and / or in the section and at least one point in time and / or in the time period can then be estimated, estimated and / or calculated.

To determine the coefficient of friction, other data can also be used. For example, sensor data from vehicles, such as data from acceleration sensors, gyro sensors, ESP sensors, yaw rate sensors or the like, as well as weather data and / or road sensor data, such as smoothness sensors, humidity sensors and / or

Temperature sensors are used to determine the coefficient of friction. The actual coefficient of friction can be determined using the road condition data and possibly other data, for example using a geostatistical method.

The method may be considered to be based on the findings described below. The current developments in the area of networked vehicles allow connectivity units to exchange

Sensor data on current lane, speed, traffic situation or the like. By processing these data and the resulting information gain over road sections, automated driving and predictive driver assistance systems can all be improved

Promote safety. The vehicle will be informed about the

Surroundings that it could not generate alone with its own sensors. In this context, the road friction coefficient and / or the coefficient of friction of the road also plays a role. There are no dedicated friction sensors for cars. However, it is due to server-side processing of many sensor data from many different vehicles (eg acceleration sensors) in combination with

Weather sensors and road-side sensors (smoothness sensors) make it possible to estimate a coefficient of friction for road sections. This information can then be used for further functional development with the aim of increasing safety and comfort.

By using the road condition data for determining the coefficient of friction, a precision of the determination of the coefficient of friction and / or an accuracy of the determined coefficient of friction can advantageously be increased. If, for example, the coefficient of friction is determined on the basis of weather data, it may happen that an excessively low coefficient of friction is estimated, since, for example, the roadway has already been cleared of snow and / or salt has been scattered. To take this into account, it is provided according to the invention to determine the coefficient of friction based on the road condition data. For example, an amount of salt on the roadway can advantageously be used to determine the coefficient of friction, since the formation of a snow and / or ice layer can be prevented by scattering salt or the layer can be degraded and / or dissolved, which is the coefficient of friction raised again. It can therefore be too Constellations come in which, for example, the weather conditions would cause low coefficients of friction, but these are not actually present, as was intervened by the scattering of salt. It may therefore be advantageous for the friction coefficient determination to know whether and how much salt was distributed on the road and / or whether the roadway has been cleared of snow.

Thus, based on the road condition data, the friction value can be estimated with higher accuracy. The road condition data can also be used to check the plausibility of a friction coefficient determined on the basis of other data.

Another advantage of the proposed method is that many road condition data, such as swarming knowledge, can be used. Thus, individual errors of the sensors have little effect and statistical evaluations can provide good results. Furthermore, by using the road condition data, a significant improvement in friction coefficient estimation can be made. Also, it is conceivable the remaining

Residual amount of a salt deposit on the road due to various

Factors, such as As weather conditions and / or traffic, and thus to improve a prediction of the coefficient of friction for a future time.

According to one embodiment of the invention, the

Road condition data Data from at least one clearing vehicle and / or from at least one road cleaning vehicle. The at least one

Clearing vehicle and / or the at least one street cleaning vehicle can be equipped with a GPS sensor and so local

Provide road condition data and / or position data. Also, the at least one clearing vehicle and / or the at least one

Road cleaning vehicle have a timer and so on

Provide time information of the road condition data.

According to one embodiment of the invention, the

Road condition data Position data of at least one clearing vehicle and / or at least one road cleaning vehicle. Alternatively or additionally, the at least part of the road condition data may be based on

Position data of at least one clearing vehicle and / or at least one road cleaning vehicle to the at least one position of the roadway be assigned. In this way it can be determined, for example, which position or which section of the roadway has been cleared of snow and / or at which position or on which section salt was sprinkled. So that the coefficient of friction at the corresponding position and / or the portion of the roadway can be determined with high accuracy.

According to one embodiment of the invention, the

Road conditions data a time information. Alternatively or additionally, the at least part of the road condition data may be based on

Time information of the road condition data are assigned to the at least one time. In this way, for example, it can be determined when a section of the road has been cleared and / or salted. In this way, it is also possible to determine the point in time and / or a time period in which the determined coefficient of friction is likely to be valid and / or high

Probability may correspond to an actual coefficient of friction of the roadway.

According to one embodiment of the invention, the correlate

Road condition data having a salt amount distributed on the road surface, a snow clearing operation, a salt type of salt distributed on the road surface, a road cleaning operation, an amount of water distributed on the road surface, and / or a slab amount distributed on the road surface. In other words, the road condition data for a salt amount distributed on the road, for a snow-clearing operation, for a salt type of a salt distributed on the road, for a

Street cleaning process, for a distributed amount of water on the road surface and / or for a distributed on the road surface Rollsplittmenge be representative and / or indicative. All the above-mentioned variables can also be specified per unit of time and / or per unit area.

According to one embodiment of the invention, the method further comprises the following step:

Deriving and / or determining, from the road condition data, a quantity of salt distributed at the at least one position of the road and at least one time on the road, one carried out at the at least one position of the road and at least one time

Snow clearing process, a salt type one at the at least one Position of the roadway and to the at least one time distributed on the road salt, one at the at least one position of the road and at least one time performed road cleaning operation, one at the at least one position of the road and at least one time distributed on the road Amount of water, and / or distributed at the at least one position of the road and at least one time on the road surface Rollsplittmenge. In other words, the road condition data can be evaluated in terms of position and time so as to enable a reliable estimation and / or determination of the coefficient of friction.

According to an embodiment of the invention, the method further comprises a step of determining a plurality of friction values at a plurality of positions of the roadway and / or for a plurality of points in time. Furthermore, the method has a step of creating a coefficient map based on the plurality of determined coefficients of friction. Such a coefficient map may be advantageous in particular with regard to an autonomous driving of vehicles, since based on such a coefficient map, for example, a speed of a vehicle can be automatically adapted to the currently existing coefficient of friction. The friction coefficient card can be a digital one

Road map with registered and / or assigned friction coefficients.

Developments in the area of networked vehicles and / or in the field of autonomous driving can, for example by means of connectivity units, an exchange of

Sensor data about a current lane, a speed, a

Traffic situation or similar allow. Through the processing of such data and the resulting information gain on the road, automated driving and predictive driver assistance systems can be driven forward with an increase in safety. The vehicle can do so

Information about the environment can be shared with it

could not generate on-board sensor technology. Since there is usually no coefficient of friction sensors for vehicles, in particular not for passenger cars, the creation and provision of the friction coefficient map can provide an additional information gain. Such coefficient map can then for further

Functional development can be used with the aim of increasing safety and comfort. Friction values entered in a coefficient of friction map can be found here for example, to automatically set vehicle speeds before bends, for example. So can dangerous situations or accidents by agreement from the lane, especially in difficult

Road conditions such as wet or snow, be avoided.

According to an embodiment of the invention, the method further comprises the step of receiving, from a road user, a request for a coefficient of friction at a request position and / or for a request time. Furthermore, the method has the step of determining the coefficient of friction at the request position and / or for the request time. Furthermore, the

Process the step of providing the determined coefficient of friction to the road user. In other words, the inventive method can be implemented, for example, in a server and / or a server-based data processing device. In this case, road users can request a friction value in real time for any request positions and / or at any desired request time, and in accordance with the ascertained

Friction, for example, a driving behavior, such as a speed adapt. Also, a functionality of the method according to the invention can be made available to any number of road users, without requiring a cost-intensive upgrade of the vehicles.

Another aspect of the invention relates to a data processing device for determining a coefficient of friction of a road, wherein the

Data processing device is adapted to perform the method as described above and below. The

Data processing device can also be a network of

Data processing devices, such as a cloud environment denote.

Features, elements, functions and / or steps of the method as described above and below may be features, elements and / or functions of the data processing device as described above and below, and vice versa.

According to one embodiment of the invention, the

Data processing device, a data memory for storing the

Road condition data, a processor, and an interface for transmitting a coefficient of friction. In the data memory can be a program element deposited, who it is carried out on the processor, which

Data processing device instructs to perform steps of the method, as described above and below. In particular, the interface may be a wireless interface for bidirectional communication between a vehicle and the data processing device. The communication can be about the Internet, a mobile network and / or a

Telephone network done. About the interface can be about the request of

Received friction coefficient of the vehicle and the friction coefficient then determined are sent to the vehicle.

Brief description of the drawings

Embodiments of the invention will now be described in detail with reference to the accompanying drawings.

Fig. 1 shows a data processing apparatus according to a

Embodiment of the invention.

Fig. 2 shows a system with a data processing apparatus according to an embodiment of the invention.

3 shows a flowchart for illustrating steps of a method for determining a coefficient of friction according to an exemplary embodiment of the invention.

The figures are only schematic and not to scale. In the figures are the same, the same or similar elements with the same

Provided with reference numerals.

Embodiments of the invention

Fig. 1 shows a data processing apparatus 10 according to a

Embodiment of the invention.

The data processing device 10 has a data memory 12 for storing road status data 14 and / or a data set 16 of road status data 14. The road condition data 14 come from a winter service 50 and / or a street cleaning service 50, which one or more vehicles 52, such as clearing vehicles 52 and / or

Street cleaning vehicles 52 may have.

Furthermore, the data processing device 10 has a processor 18. In the data memory 12 and / or another data storage device of

Data processing device 10 may be deposited about a program element which, when executed on the processor 18, the

Data processing apparatus 10 instructs to carry out steps of the method for determining a coefficient of friction μ (8, t) at a position s of the roadway and at a time t, as described above and below.

The data processing device 10 is set up to determine the coefficient of friction p (s, t) at the position s of the roadway and at the time t based on the road condition data 14. Generally describe the

Road condition data 14 a surface condition and / or a

Condition of a road surface of the roadway. So that a local and temporal friction coefficient μ can be determined, the road condition data 14

Position data of at least one clearing vehicle 52 and / or at least one road cleaning vehicle 52 include. Also, the

Road status data 14 include a time information and / or indicate a time in which the road condition data 14 has been detected. Specifically, the road condition data 14 may be representative of a salt amount distributed on the road, a snow clearing process, a salt type of salt distributed on the road, a road cleaning process, a quantity of water distributed on the road surface, and / or a rolling chippings amount distributed on the road surface , The data processing device 10 may be configured to derive this information from the road condition data so as to determine the coefficient of friction μ with high accuracy. Furthermore, the data processing device 10 has an interface 20. In particular, the interface 20 may be an interface 20 for wireless communication with a road user 22, such as a vehicle 22. By way of example, the interface 20 can be designed for bidirectional communication with the road user 22, wherein the communication can take place, for example, via the Internet, a mobile radio network, a telephone network and / or another suitable data transmission network. The

Road user 22 may be about a request for a coefficient of friction μ at a Request item and / or for a request time to the

Data processing device 10 which can receive this request via the interface 20. The data processing device 10 can also be designed and / or configured to determine the corresponding coefficient of friction μ, as described above and in detail below, and to send the coefficient of friction μ to the road user 22 via the interface 20.

Also, the data processing device 10 may receive the road condition data 14 via the interface 20. For example, the

Road condition data 14 from the winter service 50 and / or the

Street cleaning service 50, about a server of the winter service 50 and / or the street cleaning service 50, are received. Also, the vehicles 52 of the winter service 50 and / or the

Street cleaning service 50 the road condition data 14 directly to the

Data processing device 10 transmit.

The data processing device 10 may in particular designate and / or include one or more servers. For example, the

Data processing device 10 in a cloud environment and / or a

Cloud computer environment be realized.

FIG. 2 shows a system 100 with a data processing device 10 according to an embodiment of the invention. Unless otherwise described, the data processing apparatus 10 of Figure 2 has the same elements and

Features such as the data processing device 10 of Figure 1.

The system 100 includes a weather information station 102 that provides the data processing device 10 with up-to-date and / or predicted weather data, such as temperature, air pressure, humidity, precipitation rate, or the like.

Furthermore, the system 100 has a road sensor station 104, which supplies the data processing device 10 with road sensor data and / or

Road sensor data, such as smoothness sensor data,

Moisture sensor data, temperature data or the like provides. The data processing device 10 is further provided with vehicle sensor data from one or more vehicles 106. The vehicle sensor data may be data from acceleration sensors, gyro sensors, ESP sensors, yaw rate sensors or the like. These data can be wirelessly transmitted over a telephone network, in particular a mobile radio network, to the

Data processing device 10 are transmitted.

Furthermore, road condition data 14 from the winter service 50, the road cleaning service 50, and / or the vehicles 52 of the winter service 50 and the road cleaning service 50 are provided to the system 100, respectively.

Optionally, the system 100 has a connection to the Internet 108 via which additional data relating to a roadway and / or a

Road network can be queried by the data processing device 10.

Based on road condition data 14, the

Data processing device 10 a coefficient of friction μ at a position s of a road and for a time t. However, to determine the coefficient of friction μ, the data processing device 10 can also store weather data.

Use road sensor data, vehicle sensor data and / or other data so as to determine location-dependent and / or time-dependent friction coefficients μ (8, t). For this purpose, the road condition data 14, the weather data, the

Road sensor data, the vehicle sensor data and / or the other data are processed by means of a particle filter and / or a Kalman filter in time sequences to aggregate a location-dependent and / or time-dependent coefficient of friction μ. This coefficient of friction μ can then be sent to the road user 22 via the interface 20 of the data processing device 10 in order to provide the road user 22 with information about the current coefficient of friction.

Furthermore, the data processing device 10 may be configured to determine a plurality of coefficients of friction μ for different roadway positions s and / or for different times t and to generate a coefficient of friction map. The friction coefficient map may designate a road map, in particular a digital road map, with friction coefficients μ entered therein. Also, such a friction coefficient map can be sent to the road user 22. FIG. 3 shows a flow chart for illustrating steps of a method for determining a coefficient of friction μ according to an exemplary embodiment of FIG

Invention.

In a first step S1, a record 16 of road condition data 14 of a winter service 50 and / or a road cleaning service 50 is provided. Optionally, in step Sl preprocessing and / or

Evaluation of the road condition data 14 are made.

In a further step S2, at least part of the road condition data 14 is assigned to at least one position s and / or at least one section s of the road, for example based on position data of at least one clearing vehicle 52 and / or at least one road cleanup vehicle 52 Location information from the

Road condition data 14 are determined and / or derived.

In a further step S3, at least the part of the road condition data 14 is at least one time t at which the part of the road

Road condition data 14 is recorded, assigned, based approximately on

Time information of the road condition data 14. In step S3, the time information can also be derived from the road condition data 14.

In a step S4, from the road condition data 14, one at the at least one position s of the roadway and to the at least one

Time t on the roadway distributed amount of salt, at the at least one position s of the road and at least one time t performed snow removal process, a salt type at the at least one position s of the roadway and at least one time t on the roadway distributed salt a road cleaning operation performed on the at least one position s of the road and at least one time t, a quantity of water distributed on the roadway at the at least one position s of the road and at least one time t, and / or one on the at least one Position s of the road and to the at least one

Time t distributed on the road surface distributed and / or determined roller split amount. In a further step S5, at least coefficient of friction μ of the roadway at the at least one position s of the roadway and at least one time point t based on and / or using the road condition data 14 is determined. For this purpose, in particular those determined in step S4

Information used, so that the friction coefficient μ can be determined with high precision.

The above-described steps S1 to S5 can also be run through several times, so that friction coefficients μ can be determined at a plurality of different roadway positions s and / or at different times. In an optional step S6, based on this plurality of determined coefficients of friction μ, a friction coefficient map can be created, for example by

Enter the coefficients of friction μ in a road map. Alternatively or additionally, individual coefficients of friction μ can also be transmitted to a road user 22, for example via the interface 20. Also, the Reibwertkarte can be transmitted to the road user 22 and / or the Reibwertkarte can be outputted approximately on a user interface of the data processing device 10 and / or stored in the data memory 12.

In addition, it should be noted that "comprehensive" does not exclude other elements and "a" or "an" does not exclude a multitude

Embodiments have been described, can also be used in combination with other features of other embodiments described above. Reference signs in the claims are not to be considered as limiting.

Claims

claims

1 . Method for determining a coefficient of friction (μ) of a roadway,

characterized in that the method comprises the following steps:

Providing a record (16) of road condition data (14) of a winter service (50) and / or a road cleaning service (50), the road condition data (14) correlating with a road surface condition;

Associating at least a portion of the road condition data (14) with at least one position (s) of the roadway;

Assigning at least part of the road condition data (14) to at least one point in time (t) at which the part of the road

Road condition data (14) is detected; and

Determining at least one coefficient of friction (μ) of the road at the at least one position (s) of the road and at least one time (t) based on at least the part of the road condition data (14).

2. The method according to claim 1,

wherein the road condition data (14) includes data from at least one of

Clearing vehicle (52) and / or at least one

Road cleaning vehicle (52) include.

3. Method according to one of the preceding claims,

wherein the road condition data (14) position data of at least one clearing vehicle (52) and / or at least one

Road cleaning vehicle (52) include; and or

wherein the at least one part of the road condition data (14) is assigned to the at least one position (s) of the roadway based on position data of at least one clearance vehicle (52) and / or at least one road cleaning vehicle (52). Method according to one of the preceding claims,

wherein the road condition data (14) comprises time information;

and or

wherein the at least a portion of the road condition data (14) is assigned to the at least one time point (t) based on time information of the road condition data (14).

Method according to one of the preceding claims,

wherein the road condition data (14) correlates with a salt amount distributed on the road surface, a snow clearing operation, a salt type of salt distributed on the road surface, a road cleaning operation, an amount of water distributed on the road surface, and / or a slab amount distributed on the road surface ,

The method of any one of the preceding claims, the method further comprising:

Deriving from the road condition data (14), a quantity of salt distributed at least one position (s) of the road and at least one time (t) on the road, one at the at least one position (s) of the roadway and to the at least one a snow removal operation carried out at a time point (t), a salt type of a salt distributed at least one position (s) of the roadway and at least one time point (t) on the roadway, one at the at least one position (s) of the roadway and to the roadway at least one time point (t) carried out road cleaning process, one at the at least one position (s) of the road and at least one time (t) on the road surface distributed amount of water, and / or at least one position (s) of the road and to the at least one time (t) on the roadway distributed Rollsplittmenge.

Method according to one of the preceding claims, further comprising: determining a plurality of friction coefficients (μ) at a plurality of

Positions (s) of the roadway and / or for a plurality of times (t); and

Creating a friction coefficient map based on the plurality of determined coefficients of friction (μ).

8. The method of claim 1, further comprising: receiving, from a road user, a request for a coefficient of friction at a request position and / or for a request time; Determining the coefficient of friction (μ) at the request position and / or for the request time; and

Providing the determined coefficient of friction (μ) to the road user (22).

9. Data processing device (10) for determining a coefficient of friction (μ) of a roadway, wherein the data processing device (10) is adapted to perform steps of the method according to one of the preceding claims.

The data processing apparatus (10) according to claim 9, wherein the

Data processing device (10) has a data memory (12) for

Storage of the road condition data (14);

a processor (18); and

an interface (20) for transmitting a coefficient of friction (μ).