DE102018215170A1 - Method and system for exchanging friction data for vehicles - Google Patents

Abstract

The invention relates to a method for exchanging friction data. The method enables a more precise utilization of the coefficients of friction and has the following steps:
- Providing a coefficient of friction (μ) of a traffic area section (160, 170) through a database (120) to which at least a first vehicle (140) and a second vehicle (150) have access, at least data for determining the coefficient of friction (μ) partly determined on the vehicle side and made available to the database (120),
- Assigning a first coefficient of friction correction factor (k1) to the first vehicle (140) and a second coefficient of friction correction factor (k2) to the second vehicle (150), the respective coefficient of friction correction factor (k1, k2) being determined at least in part by the vehicle.
The invention also relates to a system (100) suitable for carrying out the method.

Description

The present invention relates to a method and a system for exchanging friction data of a traffic area section. The invention can be used advantageously, in particular, for vehicles that travel on such a traffic area section.

State of the art

The coefficient of friction between a vehicle, in particular its tire, and a traffic area section, such as a roadway, influences the dynamic driving limits of a vehicle with regard to longitudinal and transverse guidance. In a conventional vehicle driven by a human driver, the driver may e.g. Using empirical values, brief braking, visual perception or the like, at least to some extent, determine whether the current coefficient of friction is rather high or rather low. For example, the current coefficient of friction on a well-developed and clean road surface and when it is dry can be rather high and thus promote good static friction between the vehicle and the road surface, whereas wetness, black ice, dirt on the road surface or the like can adversely affect the coefficient of friction.

In the case of a partially or fully autonomous driving operation of a vehicle, it is more difficult to estimate the current coefficient of friction of a traffic area section, since the information of the human vehicle driver is at least partially eliminated. To counter this problem, for example, the WO 2016/120092 A1 a database-based coefficient of friction map in which information sent by sending vehicles is received and stored in the database, the information comprising at least the data describing the coefficient of friction of a road segment, the location data describing the geometric position of this segment of the road, and the time data describing the time of determination of the coefficient of friction and in data stored in the database can be called up by receiving vehicles. Although the vehicle can thus be provided with useful information on the current coefficient of friction of a traffic area section, there is a desire to be able to provide a vehicle with even more precise coefficient of friction data.

Disclosure of the invention

Embodiments of the invention provide an improved possibility for exchanging friction data of traffic areas.

• - Es wird ein Reibwert eines Verkehrsflächenabschnitts durch eine Datenbank zur Verfügung gestellt, wobei auf die Datenbank wenigstens ein erstes Fahrzeug und ein zweites Fahrzeug Zugriff haben. Die Daten zum Bestimmen des Reibwerts werden zumindest teilweise fahrzeugseitig bestimmt und der Datenbank zur Verfügung gestellt. Der Austausch der Daten zwischen der Datenbank und den Fahrzeugen kann beispielsweise über ein Datennetzwerk erfolgen.
• - Zudem erfolgt ein Zuordnen eines ersten Reibwertkorrekturfaktors zu dem ersten Fahrzeug und eines zweiten Reibwertkorrekturfaktors zu dem zweiten Fahrzeug, wobei der jeweilige Reibwertkorrekturfaktor zumindest teilweise fahrzeugseitig bestimmt wird. Der Reibwertkorrekturfaktor kann in diesem Zusammenhang als ein Maß verstanden werden, das angibt, welche fahrdynamischen Werte das betrachtete Fahrzeug im Vergleich zu einer Anzahl anderer Fahrzeuge bewerkstelligen kann. Beispielsweise können in einer Menge von Fahrzeugen mit durchgemischten Fahrzeugtypen Sportfahrzeuge höhere Reibwerte aufweisen als der Durchschnitt, was z.B. durch die Fahrzeugkonstruktion, wie etwa die Fahrwerkausgestaltung, oder durch andere Reifenmischungen usw. zustande kommen kann. Wird allerdings eine Flotte von Fahrzeugen gleichen Typs betrachtet, die also ausschließlich aus solchen Sportwagentypen besteht, könnte dasselbe Fahrzeug einen anderen Reibwertkorrekturfaktor aufweisen. Das Zuordnen des Reibwertkorrekturfaktors kann beispielsweise über ein Datennetzwerk erfolgen, wobei der Reibwertkorrekturfaktor gemeinsam mit dem Reibwert durch die Datenbank, also z.B. mit dem Reibwert verknüpft als ein Datensatz, bereitstellt werden kann. Das erste und das zweite Fahrzeug können z.B. über eine mobile Datenverbindung Zugriff auf die Datenbank haben. Das Fahrzeug kann insbesondere ein Kraftfahrzeug sein, das sich auch für einen teilautonomen oder vollautonomen Fahrbetrieb eignen kann.

A proposed method for exchanging coefficient of friction data can be carried out, for example, with a database and / or server-based system which enables the coefficient of friction data to be exchanged via, for example, a data network. The process has the following steps:

• A coefficient of friction of a traffic area section is made available by a database, with at least a first vehicle and a second vehicle having access to the database. The data for determining the coefficient of friction are determined at least in part on the vehicle side and made available to the database. The data can be exchanged between the database and the vehicles, for example, via a data network.
• In addition, a first coefficient of friction correction factor is assigned to the first vehicle and a second coefficient of friction correction factor to the second vehicle, the respective coefficient of friction correction being determined at least in part by the vehicle. In this context, the coefficient of friction correction can be understood as a measure which specifies which dynamic driving values the vehicle under consideration can achieve in comparison to a number of other vehicles. For example, in a lot of vehicles with mixed vehicle types, sports vehicles can have higher coefficients of friction than the average, which can come about, for example, from the vehicle construction, such as the chassis design, or from other tire mixtures, etc. If, however, a fleet of vehicles of the same type is considered, which therefore only consists of such sports car types, the same vehicle could have a different coefficient of friction correction. The assignment of the coefficient of friction correction can take place, for example, via a data network, wherein the coefficient of friction correction can be made available together with the coefficient of friction through the database, that is, for example, linked to the coefficient of friction as a data record. The first and the second vehicle can have access to the database, for example, via a mobile data connection. The vehicle can in particular be a motor vehicle, which can also be suitable for semi-autonomous or fully autonomous driving.

This method makes it possible to provide a more precise, in particular more plausible, coefficient of friction for a traffic area section, in that not only weather data, for example from a rain sensor of the vehicle or a weather data service, but also other vehicle-related influencing variables can also be taken into account. For example, when determining the vehicle the condition of the tires, the mix, age of the tread depth etc. can also be taken into account. In principle, the coefficient of friction correction can thus establish a clearer relationship between the coefficient of friction and a particular vehicle.

A further development provides that the respective coefficient of friction correction can be made available to the database. A data connection can be used for this, e.g. can also be configured bidirectionally, on the one hand to send the coefficient of friction correction factor determined at least partially in the vehicle to the database and on the other hand to receive the coefficient of friction and / or the possibly also adapted coefficient of friction correction from the database in the vehicle, in particular during its operation.

According to another development, the coefficient of friction can be standardized with the coefficient of friction correction. This enables a better comparison with other coefficients of friction. Here, for the standardized coefficient of friction µ (norm) e.g. apply: µ (standard) = k (vehicle) * µ (vehicle), where k (vehicle) is the coefficient of friction correction related to the vehicle and µ (vehicle) is the associated coefficient of friction.

In another development, the coefficient of friction correction factor can be determined on a vehicle-specific basis. This means that it cannot only be used for a specific vehicle, e.g. can be identified by its registration number or its vehicle identification number (VIN), but instead or in addition be assigned to a specific vehicle type, vehicle model, a specific vehicle configuration etc. The vehicle type can also be determined, for example, from the vehicle identification number (VIN) and / or other key numbers. This enables an even more objective assessment of the coefficient of friction, in particular the proportion thereof, which is dependent on the vehicle type.

According to a further development, a warning can be provided for the respective vehicle, e.g. as signal data or the like if the coefficient of friction related to the vehicle and corrected by the coefficient of friction correction factor deviates inadmissibly from a warning threshold. In this way, certain vehicles and / or drivers of a specific vehicle can be warned even more precisely or can be specifically informed about a warning or the like. In particular, an individual warning of a vehicle is possible. For example, for a traffic area section, there may be a danger to a vehicle due to wetness, e.g. has tires with a shallow tread depth on one or both axles, while there is no immediate danger for another vehicle with a high tread depth. In this case, one vehicle can be warned in a timely manner before reaching the traffic area section, while the other vehicle can be warned accordingly. This can prevent unwanted or unnecessary warnings. For the provision of the warning, e.g. apply: µ (norm) <µ (warning) * k (vehicle), where µ (norm) is the standardized coefficient of friction, µ (warning) the warning threshold and k (vehicle) is the coefficient of friction correction related to the vehicle.

Another development provides that the coefficient of friction correction factors are compared between at least the first vehicle and the second vehicle, a problem of the respective vehicle being concluded if the coefficient of friction correction factors deviates. In other words, the coefficient of friction correction factors among themselves, i.e. among the vehicles are compared with each other to identify vehicle-specific problems, such as tires with insufficient tread depth. This can be carried out in particular in vehicle fleets of a certain vehicle type, so that an outlier can be clearly identified among the coefficient of friction correction factors.

It is also possible for the database to identify abnormal states of the respective vehicle. For this purpose, for example, the coefficient of friction correction factors can be filtered according to a specific model and / or vehicle type and this can be viewed as a distribution. The bottom x% of the vehicles can then be informed accordingly that there may be a malfunction on the vehicle side.

As mentioned above, the coefficient of friction correction can be provided or sent from the database. In one development, the coefficient of friction correction factor for vehicles of identical, same or at least similar type can have at least one essentially identical initial value. This can e.g. the current average coefficient of friction correction for this vehicle type or this vehicle model or in the initial state 1. During the operation of the vehicle, with the aging of certain vehicle parts etc., this value can then be measured on the vehicle side be adjusted algorithmically.

Another development provides that the coefficient of friction correction factors of the vehicles can mutually influence one another. This can be particularly the case if the vehicles are in a similar or the same location at a similar or the same time. In other words, when the first and second vehicles meet, that is if they provide a value for the coefficient of friction correction within narrow geographical and / or topographical and temporal limits, the respective ones Coefficient of friction correction factors are redistributed. These limits can be freely defined. For example, these smaller fleets can be defined more generously, since the specific coefficient of friction correction becomes more meaningful from a certain frequency. Furthermore, points and times can be identified at which traffic area sections often provide similar values - due to the same surface and weather conditions - in order to additionally increase the number of meetings. At such a meeting, the coefficients of friction correction of the vehicles can be redistributed in accordance with the determined, for example measured, coefficients of friction. For redistribution based on mean values, for example: $$k\left(\mathrm{<figure-callout\; id="1"\; label="F\; e.g.\; G"\; filenames="DE102018215170A1\_0003.png"\; state="\{\{state\}\}">F\; </figure-callout>}\mathrm{e.g.}G\mathrm{1,}neu\right)=\frac{\mathrm{\mu }\left(F\mathrm{e.g.}G1\right)}{{\displaystyle \sum \mathrm{\mu }}}\ast {\displaystyle \sum k\left(alt\right)}$$

The coefficient of friction correction of the vehicle can preferably increase with the higher measured coefficient of friction and decrease that of the other vehicle, since they have experienced a comparable situation. This decrease or increase can be linear, exponential, logarithmic, or a combination thereof.

According to another further development, at least data from a vehicle dynamics control system of the respective vehicle can be evaluated for determining the coefficient of friction correction on the vehicle. From this, e.g. Information on the slip behavior is determined, with data already being available for a specific, in particular temporally and spatially determined, traffic area section, so that a worn tire or the like can be inferred from a slip that is not expected per se, and a comparatively low coefficient of friction correction may be derived therefrom can.

The invention also relates to a system for exchanging friction data. The system can be computerized and e.g. be server-like with a data connection. The system has a database which is set up to provide an at least partially determined coefficient of friction for a traffic area section of at least a first vehicle and a second vehicle. The database is also set up to assign a vehicle-specific first coefficient of friction correction to the first vehicle and a vehicle-specific second coefficient of friction correction to the second vehicle.

The system can be operated using the methods explained above in one or more of the embodiment variants described and thus offers the advantages explained above.

Further measures improving the invention are described below together with the description of the preferred exemplary embodiments of the invention with reference to figures.

Figure list

• 1 eine schematische Übersicht über ein System zum Austausch von Reibwertdaten zwischen einer Datenbank und einer Mehrzahl von Fahrzeugen und
• 2 ein Flussdiagramm eines Verfahrens zum Austausch von Reibwertdaten.

In the following, advantageous exemplary embodiments of the invention are described in detail with reference to the accompanying figures. Show it:

• 1 a schematic overview of a system for exchanging friction data between a database and a plurality of vehicles and
• 2nd a flowchart of a method for exchanging friction data.

The figures are only schematic and are not to scale. In the figures, the same, equivalent or similar elements are provided with the same reference numerals throughout.

Embodiments of the invention

1 shows a system 100 , which is suitable for the electronic exchange of friction data, e.g. using cloud computing. The system 100 has a server 110 having a memory for program instructions, a processor for executing the program instructions, etc. via a database 120 that are functional with the server 100 is connected, and via a communication interface 130 to a data network, which in particular enables a radio connection.

Furthermore, the system points 100 here two vehicles as examples 140 , 150 on that over a first data connection 141 , 151 , which are only indicated by two symbols, each access to the server 110 or have the database. The vehicles are also standing 140 , 150 over a second data connection 142 , 152 in contact with each other, whereby this is only exemplarily indicated as a separate data connection and, for example, centrally via the communication interface 130 can be done. The data connections 141 , 151 respectively. 142 , 152 accomplishes, for example, a radio module in the respective vehicle 140 respectively. 150 is installed. The data connection 141 , 151 respectively. 142 , 152 is bidirectional and allows receiving and sending data both on the server side and on the vehicle side. It should be noted that the system 100 For example, it can also be accessible by vehicle fleet, so that dozens, hundreds, thousands or even millions of vehicles can be integrated.

The first vehicle 140 drives on a first traffic area section 160 and the second vehicle 150 drives a second Traffic area section 170 which may be geographically far apart and which are, for example, roads with, for example, paved road surfaces. The determination of the coefficient of friction data of the traffic area sections to be exchanged 160 , 170 takes place at least partially on the vehicle side, for which purpose a control unit (not specified) of the vehicles 140 , 150 accesses data from a vehicle dynamics control system and, for example, an anti-lock braking system and an anti-slip control system.

The system 100 can be operated as described below, the server-side functions being contained in the stored program instructions and being executed by the processor in order to also control the communication interface 130 as well as the database 120 to cause.

In principle, the vehicles collect 140 , 150 data on the coefficient of friction µ of the traffic area section they are traveling on 160 , 170 and send it to the database at a definable frequency, for example with additional information about location, time, weather, etc. 120 . This processes the sent data and, if necessary, supplements it with further information, such as other weather data. In addition, the vehicles 140 , 150 collected data can be checked for plausibility among themselves. The in the database 120 collected data are available to all vehicles 140 , 150 are available and are either made available in the form of map data from a navigation system as a data block or selectively for individual traffic area sections to be traveled as individual data.

In this embodiment it is possible, for example, that the vehicle 140 from the database at time t1 120 Data on the coefficient of friction µ of the road section 160 receives that at a time t0 from the vehicle 150 while driving on the road section 160 were collected. Conversely, the vehicle can 150 at time t2 data on the coefficient of friction µ of the road section 170 get that from the vehicle 140 were collected at time t1.

To the for the vehicles 140 , 150 To support the provided coefficient of friction µ, a first coefficient of friction correction factor k1 is additionally provided by the first vehicle 140 and a second coefficient of friction correction factor k2 from the second vehicle 150 determined to the database 120 transmitted and processed there or in the server. The coefficient of friction correction k1, k2 is vehicle-specific and / or vehicle-type-specific and can, at least over a period of time, differ from the vehicle 140 to vehicle 150 differentiate. The coefficient of friction correction factor k1, k2 contains, for example, a statement about the quality of the road holding of the vehicle under consideration 140 , 150 etc. Thus the database represents 120 a combination of the coefficient of friction µ and the coefficient of friction correction factor k1, k2 are available.

Database 120 or the system 100 use the coefficient of friction correction factor k1, k2 to normalize the coefficient of friction µ, so that in this exemplary embodiment the following applies: µ (norm) = k (vehicle) * µ (vehicle). This enables a more precise determination of the coefficient of friction µ and a more precise comparison of the coefficient of friction µ, since vehicle-related influencing variables are taken into account more precisely. A lower coefficient of friction μ can also be negatively influenced by a comparatively poor vehicle condition, which can be recognized by the additional coefficient of friction correction factor k1, k2.

Furthermore, the system 100 set up to send out a vehicle-specific warning when a warning threshold value for the respective vehicle 140 , 150 taking into account the specific coefficient of friction correction k1, k2, where: µ (norm) <µ (warning) * k (vehicle).

In the event that the vehicles 140 , 150 Drive in the same traffic area section at a definable time interval, for example the traffic area section 160 , is the system 100 set up to initiate a mutual influencing of the coefficient of friction correction factors k1 and k2, whereby the following applies: $$k\left(\mathrm{<figure-callout\; id="1"\; label="F\; e.g.\; G"\; filenames="DE102018215170A1\_0003.png"\; state="\{\{state\}\}">F\; </figure-callout>}\mathrm{e.g.}G\mathrm{1,}neu\right)=\frac{\mathrm{\mu }\left(F\mathrm{e.g.}G1\right)}{{\displaystyle \sum \mathrm{\mu }}}\ast {\displaystyle \sum k\left(alt\right)}$$

In 2nd For the sake of clarity, the method described above is shown again in a flow chart. In one step S1 the friction coefficient µ traffic area section is provided 160 , 170 through the database 120 to the vehicles 140 , 150 . In one step S2 the first coefficient of friction correction k1 is assigned to the first vehicle 140 and the second coefficient of friction correction factor k2 to the second vehicle 150 .

QUOTES INCLUDE IN THE DESCRIPTION

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Patent literature cited

• WO 2016/120092 A1 [0003]

Claims (10)

Method for exchanging coefficient of friction data, comprising the steps of: providing a coefficient of friction (μ) of a traffic area section (160, 170) through a database (120) to which at least a first vehicle (140) and a second vehicle (150) have access, wherein data for determining the coefficient of friction (µ) is determined at least partially on the vehicle side and made available to the database (120), characterized by - assigning a first coefficient of friction correction factor (k1) to the first vehicle (140) and a second coefficient of friction correction factor (k2) to the second vehicle (150), the respective coefficient of friction correction (k1, k2) being determined at least partially on the vehicle side. Procedure according to Claim 1 , characterized in that the respective coefficient of friction correction (k1, k2) is made available to the database. Procedure according to Claim 1 or 2nd , characterized in that the coefficient of friction (µ) is standardized with the coefficient of friction correction (k1, k2). Method according to one of the preceding claims, characterized in that the coefficient of friction correction (k1, k2) is determined specifically for the vehicle type. Method according to one of the preceding claims, characterized in that a warning is provided for the respective vehicle (140, 150) when the coefficient of friction (µ) corrected by the coefficient of friction correction (k1, k2) related to the vehicle (140, 150) deviates from a warning threshold value (µ (Warn)) inadmissibly. Method according to one of the preceding claims, characterized in that the coefficient of friction correction factors (k1, k2) are compared between at least the first vehicle and the second vehicle, wherein if the coefficient of friction correction factors (k1, k2) deviates, a problem of the respective vehicle is concluded. Method according to one of the preceding claims, characterized in that the coefficient of friction correction factor (k) for vehicles of identical type has at least one essentially identical initial value. Method according to one of the preceding claims, characterized in that the coefficients of friction correction (k1, k2) of the vehicles (140, 150) mutually influence one another if the vehicles are at a similar or the same time at a similar or the same location. Method according to one of the preceding claims, characterized in that at least data from a vehicle dynamics control system of the respective vehicle is evaluated for determining the coefficient of friction correction factor (k) on the vehicle. System (100) for exchanging coefficient of friction data, with a database (120), which is set up to determine an at least partially determined coefficient of friction (µ) on the vehicle side for a traffic area section (160, 170) of at least a first vehicle (140) and a second vehicle ( 150), characterized in that the database (120) is further configured to assign a vehicle-specific first coefficient of friction correction factor (k1) to the first vehicle (140) and a vehicle-specific second coefficient of friction correction factor (k2) to the second vehicle (150).

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