METHOD AND DEVICE FOR DETERMINING AT LEAST ONE ROAD CONTACT PARAMETER OF A VEHICLE

Description

[0001] The invention relates to a method and a device for determining at least one road contact parameter of a vehicle, which represents a road surface and / or tire property of the vehicle.

[0002] Methods are known from the prior art that use sensors installed in the vehicle, such as ultrasonic sensors, piezoelectric sensors, or accelerometers, to determine parameters that define the properties of a road surface and / or the tire. Such parameters include, among others, road surface wetness, coefficient of friction, road roughness, tire type, tire wear, and / or snow cover.

[0003] Other known methods first determine the degree of road wetness, then the road roughness, and then the degree of tire wear. For this purpose, various frequency ranges of the signals generated by the sensors described above are evaluated.

[0004] US Patent 2015 / 02160614 A1 discloses a method and a system for collecting and / or monitoring road properties. The patent describes how type-specific calibration data is used to determine a road condition category. This calibration data consists of predetermined relationships between vehicle movement parameters and road condition classes.

[0005] Also known is EP 2 950 290 A1, which concerns the provision of traffic information. This document describes how control information can include information about road conditions, in particular wetness.

[0006] DE 10 2016 221 975 A1 relates to a method for operating a driver assistance system for motor vehicles, each of which has several wheels in contact with a road surface, wherein at least one of the motor vehicles determines at least one current coefficient of friction between at least one of the wheels and the road surface by means of at least one friction coefficient model, and wherein at least one driver assistance device of the respective motor vehicle is adjusted or calibrated depending on the determined coefficient of friction.

[0007] WO 2019 / 063589 A1 refers generally to systems and methods for estimating the friction between a road surface and a vehicle tire.

[0008] DE 10 2018 214 882 A1 concerns a method for determining a maximum coefficient of friction between a vehicle tire and a road surface.

[0009] US 2015 / 260614 A1 concerns a method and system for recording and / or monitoring road conditions, which is easily accomplished with relatively simple means and at the same time allows for scalability and general usability.

[0010] The technical problem is to create a method and a device for determining at least one road contact parameter of a vehicle that enables an accurate and reliable, and in particular robust, determination of the road contact parameter.

[0011] The solution to the technical problem is provided by the articles with the features of the independent claims. Further advantageous embodiments of the invention are described in the dependent claims.

[0012] A method for determining at least one road contact parameter of a vehicle is proposed. The vehicle can be, in particular, a motor vehicle. The vehicle contact parameter represents a road property. A road property can be, in particular, the degree of road wetness, the degree of snow cover, or the road roughness. The road contact parameter can also represent a tire property of the vehicle. Such a parameter can, for example, represent a tire type or a degree of tire wear. It is also possible for the road contact parameter to represent both road and tire properties. In this case, the road contact parameter can, for example, represent a coefficient of friction between the road and the tire.

[0013] The procedure involves defining at least one calibration section within a road network. The calibration section can be a road segment, in particular a carriageway segment or a lane segment. A carriageway segment can comprise multiple lanes. The calibration section can have a predetermined length. In particular, the calibration section is thus a sub-segment of a road within the road network.

[0014] The road network can refer to the entire structure of roads within a predetermined traffic area, for example, within a region, a city, or a country. Furthermore, information about the size and spatial location of the calibration section in a reference coordinate system, such as a global reference coordinate system, may be assigned to the calibration section.

[0015] Furthermore, at least one section-specific value or range of values ​​for at least one road contact parameter is assigned to the calibration section. The assignment of a section-specific value or range of values ​​to the calibration section means that the value of the road contact parameter does not change, or changes no more than a predetermined amount, within the calibration section. In particular, the value within the calibration section can be constant or essentially constant. The value or range of values ​​can be predetermined or determined in a manner explained below.

[0016] Information about the calibration section, in particular its spatial location and / or size, as well as the section-specific value or value range, can be stored in a retrievable manner, especially in a storage device. Preferably, information about the calibration section and the section-specific value or value range is stored in a server device and made available in a retrievable manner. This server device can be a participant in a network, for example, the internet, whereby a vehicle or a vehicle communication device can also be a participant in this network, which can retrieve information via the network. In this case, this information can be retrieved, in particular by a vehicle, especially via wireless communication. However, the information can also be stored in a storage device located in the vehicle.

[0017] The next step is to determine whether the vehicle is located within the calibration section. For this purpose, the vehicle's (own) position can be determined, for example, by evaluating the output signals of at least one position sensor. Suitable position sensors are known to those skilled in the art. A position sensor can, in particular, be a GNSS sensor. Of course, other position sensors can also be used. Furthermore, it can be determined that the vehicle is located within the calibration section if its position lies within the spatial area of ​​the calibration section by retrieving information about the location of the spatial area, and in particular its size and / or shape – as explained above – from a storage device.

[0018] Furthermore, at least one road contact parameter is determined by evaluating at least one output signal from a vehicle sensor, whereby the output signal is generated during the vehicle's journey in the at least one calibration section.

[0019] The vehicle sensor can be, in particular, a sensor whose output signal changes when road surface conditions and / or tire properties change. Examples of such vehicle sensors include ultrasonic sensors, piezoelectric sensors, which are installed, for example, in a wheel arch liner of the vehicle, or acceleration sensors, which are arranged, for example, in the tread of the tire.

[0020] It is also possible that several road contact parameters, in particular two or more than two road contact parameters, are determined by evaluating an output signal from a single vehicle sensor or by evaluating output signals from several vehicle sensors, whereby these output signals / this output signal are generated during the vehicle's journey in the at least one calibration section.

[0021] It is also possible for a calibration section to be a parameter-specific calibration section. This can mean that only one or more selected road contact parameters are assigned to a calibration section, whereby these road contact parameters assigned to the calibration section are determined by evaluating the at least one output signal. Information about the assignment of a road contact parameter to a calibration section can be stored in a retrievable manner, as described above. If the calibration section is a parameter-specific calibration section, a road contact parameter that differs from the road contact parameter(s) assigned to the calibration section is not determined by evaluating the output signal of the vehicle sensor, which is generated during the vehicle's travel within the at least one calibration section.

[0022] The calibration section within the road network can be defined, in particular, such that the at least one road surface contact parameter can be determined as reliably as possible within the calibration section. Specifically, the calibration section can be defined such that the variation in road surface properties within the calibration section is less than a predetermined threshold. This can mean that at least one road surface property, preferably several, lies within a range of values, where the difference between a maximum and minimum value of the range is less than or equal to a predetermined threshold. The calibration section can also be defined such that the variation of at least one road surface property in the direction of travel along the calibration section is less than a predetermined threshold.Alternatively or cumulatively, the calibration section can be defined such that the variation in the road surface properties perpendicular to the direction of travel is less than a predetermined threshold.

[0023] Alternatively or cumulatively, the at least one calibration section can be defined such that a change in at least one road surface property is reproducible. This can mean that a deviation between the maximum and minimum values ​​of a set of road surface properties is less than or equal to a predetermined threshold, where the road surface properties are determined by the same vehicle during a predetermined number of passes through the calibration section. Such changes in road surface properties can result, for example, from changing road markings or lane boundaries along the calibration section.

[0024] Alternatively or cumulatively, the at least one calibration section can be defined in such a way that one or more causes leading to changes in the at least one road surface property can be reliably detected and then taken into account when determining the road surface contact parameter. A cause can be detected, for example, by an (additional) vehicle sensor, such as a radar sensor or an image acquisition device, in particular a vehicle camera. This makes it possible to additionally consider output signals from the vehicle sensor when determining the at least one road surface contact parameter, as these signals detect causes of non-road surface-related changes in the output signals. Such non-road surface-related causes could include, for example, lane markings and / or other vehicles.

[0025] This can mean that a causal relationship between the detection of the cause and the change in at least one road surface property, and in particular the change in the output signal of the vehicle sensor, is reproducible. This, in turn, can mean that—if both the cause and the change are detected for a predetermined number of passages through the calibration section with the same vehicle—the difference between the maximum and minimum values ​​of this quantity of cause-related change in at least one road surface property is smaller than a predetermined threshold.

[0026] In a further embodiment, the presence and, if applicable, at least one further property of a road boundary and / or another vehicle is determined by evaluating an output signal of at least one (additional) vehicle sensor during the vehicle's journey in the at least one calibration section, wherein the at least one road contact parameter is determined by evaluating the at least one output signal of the vehicle sensor for detecting road contact properties as well as depending on the output signals of the (additional) sensor.

[0027] Alternatively or cumulatively, at least one calibration section can be defined such that a change in at least one road surface property caused by an undetectable cause is less than a predetermined threshold. Such an undetectable cause could be, for example, road surface contamination, e.g., by sand. Furthermore, an undetectable cause could be background noise, e.g., from other vehicles.

[0028] Determining the road contact parameter during driving in the defined calibration section advantageously allows for reliable and accurate determination of the road contact parameter, since – as explained above – the assignment of a section-specific value or range of values ​​ensures that the road contact parameter does not change, or does not change by more than a predetermined amount, in the calibration section.

[0029] Furthermore, according to the invention, the at least one road contact parameter determined in this way, in particular its value, is compared with the section-specific value or value range. For example, a difference can be determined between the road contact parameter determined for the vehicle's journey in the calibration section and the corresponding section-specific value. Such a difference can also be determined between a minimum value, a mean value, or a maximum value within the value range. It can also be determined whether the road contact parameter lies within the value range.

[0030] According to the invention, a calibrated state of an uncalibrated vehicle is established using the section-specific value or range of values, or an uncalibrated state of a calibrated vehicle is detected when the at least one road contact parameter deviates from the section-specific value or range of values ​​by more than a predetermined amount. This can be the case, in particular, if the difference described above is greater than a predetermined threshold. It can also be the case if the road contact parameter is not within the predetermined range of values.

[0031] A vehicle can be in a calibrated or an uncalibrated state. In a calibrated state, the vehicle can also be referred to as a calibrated vehicle. In an uncalibrated state, the vehicle can also be referred to as an uncalibrated vehicle.

[0032] A calibrated state can be established from an uncalibrated state by adjusting the determination of the road contact parameter through evaluation of at least one output signal from the vehicle sensor in such a way that the road contact parameter represents the actual road contact property or does not deviate from this actual road contact property by more than a predetermined amount. This can be the case if the road contact parameter determined as proposed does not deviate from the section-specific value or value range by more than a predetermined amount.

[0033] If parameters are used, for example, to determine, and in particular evaluate, the output signal—such as parameters of mathematical operations—the calibration may include determining these parameters. The calibration may also include determining filter parameters for filtering the output signal. Furthermore, the calibration may include selecting one or more mathematical operations for determining the road contact parameter and, if applicable, their sequence. It is understood by those skilled in the art that the calibration may also include further measures by which the determination of the road contact parameter can be adjusted.

[0034] In particular, the calibration can be carried out in such a way that the at least one road contact parameter, which is determined by evaluating the at least one output signal which was determined during the journey of the vehicle in the at least one calibration section, does not exceed a predetermined value of a section-specific value or value range, or lies within the section-specific value range.

[0035] This advantageously results in a reliable calibration of the vehicle, enabling it to reliably and accurately determine a road contact parameter even in sections of the road network that differ from the calibration section.

[0036] If the vehicle is calibrated and the described deviation between the road contact parameter determined as proposed is detected within the section-specific value or value range, then an uncalibrated state of the vehicle can also be detected. Information about an uncalibrated state can be transmitted to a driver and / or a higher-level system. The driver can be informed of an uncalibrated state, for example, audibly, visually, or in another way. It is also possible for such information to be transmitted to a vehicle (assistance) system. Furthermore, the operation of the vehicle, in particular a function of a vehicle (assistance) system, can be adapted to an uncalibrated or calibrated state.

[0037] This advantageously results in reliable detection of a (newly occurring) uncalibrated state. Such an uncalibrated state can occur, for example, when a tire has been changed, the tire wear has changed by more than a predetermined amount, the vehicle's payload has changed by more than a predetermined amount, or other modifications or defects have been made to the vehicle. Thus, even non-specific causes of changes in the vehicle's calibrated state can be detected.

[0038] The method also advantageously enables the monitoring or validation of a road contact parameter determined independently of the proposed method, e.g., a degree of tire wear determined as a function of mileage and / or a wear counter, a tire change detected as a function of a changed ratio of rotational speed to GPS speed of the vehicle and / or as a function of a tire pressure sensor.

[0039] If a vehicle passes through calibration sections, confirmation of the calibrated state can be performed in each calibration section.

[0040] In a further embodiment, to achieve the calibrated state, i.e., during calibration, the evaluation of the output signal is adjusted such that the at least one road contact parameter does not deviate from the section-specific value or value range by more than a predetermined amount. This and the corresponding technical advantages have already been explained above.

[0041] In a further embodiment, a calibrated state of an uncalibrated vehicle is established using section-specific values ​​or value ranges from at least two different calibration sections. In particular, the at least two different calibration sections can have different section-specific values ​​or value ranges of the at least one road contact parameter, or these different values ​​or value ranges can be assigned to the at least two different calibration sections.

[0042] This advantageously increases the reliability and accuracy of the calibration and thus also the reliability and accuracy of the vehicle-specific road contact parameter calibrated in this way. It is possible that different tire types and / or tires with different degrees of wear, even with identical road surface characteristics, especially within a single calibration section, can lead to the same output signals from the vehicle sensor, making accurate calibration more difficult.

[0043] By using section-specific values ​​or value ranges from multiple calibration sections, the probability can be increased that different tire types and / or tires will also lead to different output signals, which in turn improves the reliability of the calibration.

[0044] In a further embodiment, the at least one calibration section is determined based on design information. Design information can include, for example, information about the completion or repair date of a road section. Furthermore, design information can include information about road curvature, particularly in the longitudinal and / or transverse direction. Design information can also include information about the properties of a road surface used. Additionally, design information can include information about the properties, in particular the presence and spatial location, of road markings and / or road boundaries.

[0045] For example, a road segment can be designated as a calibration section if the time difference between the current time and the completion date or the last maintenance date is less than a predetermined threshold. Alternatively or cumulatively, a road segment can be designated as a calibration section if the curvature of the road surface is less than a predetermined threshold. Furthermore, alternatively or cumulatively, a road segment can be designated as a calibration section if the properties of the road surface used meet predetermined specifications or deviate from them by no more than a predetermined amount. Alternatively or cumulatively, a road segment can also be designated as a calibration section if the properties of road boundaries and / or lane markings meet predetermined specifications.

[0046] Alternatively or cumulatively, at least one calibration section is determined based on weather information. For example, a road segment can be designated as a calibration section if rain or snowfall is detected in that area, or if the time between the last occurrence of rain or snowfall in that area and the current time is no longer than a predetermined period. However, it is also possible for a road segment to be designated as a calibration section if no rain or snowfall is detected in that area and / or if the time between the last occurrence of rain or snowfall in that area and the current time is longer than a predetermined period.

[0047] Alternatively or cumulatively, at least one calibration section is determined based on traffic information. For example, a road segment can be designated as a calibration section if its traffic rate exceeds a certain threshold, where the traffic rate refers to the number of vehicles traveling on or through the road segment within a predetermined time interval.

[0048] It can be assumed that at high traffic rates, undetectable influences on a road surface property are minimal, for example, contamination by sand.

[0049] Alternatively or cumulatively, a road segment can be designated as a calibration section if the traffic rate is less than a further predetermined threshold. This advantageously ensures that interference from other vehicles in the calibration section does not affect the determination of the road contact parameter, or only to a tolerable extent, thereby increasing the accuracy of the determination.

[0050] The explained determination of the calibration section based on this information advantageously enables the identification of road sections that are suitable for accurately determining the road contact parameter, thereby increasing the accuracy of the subsequent determination.

[0051] In a further embodiment, an activation state of a calibration section is determined, wherein the determination of at least one road contact parameter by evaluating at least one output signal of a vehicle sensor only occurs when an active state of the calibration section is detected. Information about an activation state can be assigned to the calibration section and, as explained above, can also be stored in a retrievable manner. An activated state refers to a state of the calibration section in which the road contact parameter determined by a calibrated vehicle does not deviate from the section-specific value or range by more than a predetermined amount, or in which a reliable determination of the value / range by a calibrated vehicle is possible.

[0052] A deactivated state refers to a state of the calibration section in which the road contact parameter determined by a calibrated vehicle deviates from the section-specific value or range by more than a predetermined amount, or in which a reliable determination of the value / range by a calibrated vehicle is not possible.

[0053] It is possible for the activation state to be set depending on design information, weather information, and / or traffic information. For example, an activated state for the calibration section can be set when the traffic rate is within a predetermined range, and a deactivated state when the traffic rate is outside that range. An activated state can also be set when rain or snow falls within the calibration section, or when no more than a predetermined time has elapsed since the last occurrence of snow or rain, or when no snow or rain falls and / or when more than a predetermined time has elapsed since the last occurrence of snow or rain.

[0054] It is important to note that the amount of road moisture kicked up is significantly greater with a high axle load than with a low axle load on a vehicle driving on the road. Heavy vehicles, for example, kick up not only the surface moisture but also the moisture that has penetrated deeper into the road surface. This is most noticeable, for instance, on a road surface that has been driven over by many light vehicles and is therefore superficially dry, where a heavier vehicle, such as a truck, then kicks up a considerable amount of moisture. This is because a tire, which is pressed against / into the road surface with high force, digs into it particularly deeply. This fact is important to consider when, for example, a method for determining the degree of road wetness is to be calibrated on a wet road surface. Ideally, the calibration should be performed when the road surface has only been lightly wetted.This can be ensured if a corresponding calibration section is only activated as a calibration section for a predetermined period of time after the end of the rainfall.

[0055] In this case, after determining whether the vehicle is in the calibration section, it can be determined whether the calibration section is in an activated or deactivated state, whereby the determination of at least one road contact parameter only takes place if the calibration section is in an activated state.

[0056] This ensures that the road contact parameter is determined as accurately as possible, since no determination follows in a road section designated as a calibration section, which does not allow for a determination with the desired reliability.

[0057] In another embodiment, the activation state of the calibration section is set depending on weather and / or traffic information. This and its corresponding advantages have already been explained.

[0058] In a further embodiment, at least one road contact parameter is determined for a road segment by a plurality of calibrated vehicles. Furthermore, the road segment is designated as a calibration segment, or the designation of the road segment as a calibration segment is maintained, or a deactivated calibration segment is activated, if the road contact parameters determined by at least a predetermined number of calibrated vehicles within a predetermined time interval do not differ from each other by more than a predetermined amount. In other words, the variation in the road contact parameters determined by several calibrated vehicles for the road segment is analyzed, whereby the designation as a calibration segment occurs or is maintained, or an activated state of the calibration segment is set, only if the variation is less than a predetermined threshold.

[0059] In this case, it can be assumed that the road surface properties of the road segment will not change, or will change only by a predetermined amount, since a number of calibrated vehicles determine essentially the same road surface contact parameters. This advantageously allows such road segments to be used as calibration sections for determining a road surface contact parameter, enabling a reliable and accurate determination of that parameter.

[0060] Furthermore, the road section will not be designated as a calibration section, or the designation of the road section as a calibration section will not be maintained, or the calibration section will be deactivated if the parameters determined in the predetermined time interval by at least a predetermined number of calibrated vehicles differ from each other by more than a predetermined amount, or if the number of road contact parameters determined in the predetermined time interval is less than a predetermined threshold.In other words, a road section will not be used as a calibration section if the previously explained variation is greater than a predetermined threshold or if the number of calibrated vehicles determining at least one road contact parameter in the relevant road section is less than a predetermined threshold, which does not allow for a reliable determination of constant or substantially constant road surface characteristics.

[0061] This advantageously results in road sections that are (temporarily) unsuitable for the reliable and accurate determination of a road contact parameter not being used for its determination, and road sections for which no reliable statement can be made about the constancy of road properties are also not being used for the determination of the road contact parameter.

[0062] Overall, this advantageously results in an improvement in the reliability and accuracy of determining the road contact parameter.

[0063] In a further embodiment, for a calibration section or a road section not designated as a calibration section, the section-specific value or value range of the at least one road contact parameter is determined or updated depending on at least one road contact parameter determined by at least one calibrated vehicle. Preferably, for a calibration section or a road section not designated as a calibration section, the section-specific value or value range of the at least one road contact parameter is determined or updated depending on road contact parameters determined by calibrated vehicles. For example, an average value from a predetermined number of calibrated vehicles in a road section or a road section not designated as a calibration section can be used.In a calibration section, specific road contact parameters are determined and defined as the section-specific value for that calibration or road section. It is also possible to define a range of values ​​that includes, for example, a predetermined percentage (e.g., more than 75%) of the road contact parameters determined by a predetermined number of calibrated vehicles for the road section or calibration section.

[0064] Furthermore, it is possible that the section-specific values ​​or value ranges determined in this way, which may contain information about the location of the respective road section, can be stored in a retrievable manner in a storage device, such as the server device described above. This advantageously enables the creation of a road contact parameter map. In particular, it is therefore possible to store the road contact parameter on a section-specific basis. This information can then be retrieved by other vehicles, for example, for vehicle operation, such as through operation adapted to the section-specific road contact parameter.

[0065] In particular, it is possible to create a wetness map that includes information about the wetness levels of different road sections. Naturally, a road roughness map and a snow cover map can also be created in a similar manner.

[0066] The development of a road contact parameter map advantageously allows vehicles to use the relevant information for vehicle control or operation, thus improving operational safety. The proposed method can also minimize the calibration effort required to determine road contact parameters. In particular, it is possible to fully calibrate an uncalibrated or partially calibrated vehicle by driving it through at least one, but preferably several, defined calibration sections. This allows calibration to be performed not immediately after the vehicle's manufacture, but rather, and especially automatically, when the vehicle is first put into operation after purchase.

[0067] According to the invention, the road contact parameter, which was determined by a calibrated vehicle, is assigned to a weight or weight range of vehicles.

[0068] Thus, it is possible for each calibration section to be assigned several section-specific values ​​or value ranges, each of which in turn is assigned to different vehicle weights or weight ranges. According to the invention, the weight- and section-specific value of the road contact parameter or value range is taken into account for the calibration of a vehicle or for monitoring the calibration status.

[0069] A further proposal is for a device for determining at least one road contact parameter representing a road surface and / or tire property of a vehicle, wherein the device comprises at least one vehicle sensor and at least one evaluation unit. The evaluation unit can be configured as a computing unit. This can include a microcontroller or an integrated circuit, or be configured as such.

[0070] According to the invention, the device comprises at least one means for detecting a defined calibration section in a road network, to which a section-specific value or range of values ​​of the at least one road contact parameter is assigned. This means can in particular include a position determination device for determining the vehicle's own position.

[0071] This device can, for example, include a communication device for retrieving information about defined calibration sections as well as information about the position in a reference coordinate system. Such information can be retrieved from a server device via the communication device, particularly wirelessly.

[0072] Furthermore, the detection system determines whether the vehicle is located within a calibration section. This can be achieved, in particular, by comparing the vehicle's own position with information about the spatial location of calibration areas. Additionally, the evaluation unit determines at least one road contact parameter by evaluating at least one output signal from the vehicle sensor, whereby the output signal is generated while the vehicle is driving within the at least one calibration section.

[0073] Furthermore, the device may include a means for determining the section-specific value or range of values.

[0074] The device is designed such that a method according to one of the embodiments described in this disclosure can be carried out to determine at least one road contact parameter of the device. Thus, the device enables the implementation of a method with the corresponding technical advantages explained.

[0075] The invention is explained in more detail using exemplary embodiments. The figures show: Fig. 1 a schematic flowchart of the method according to the invention for determining at least one road contact parameter of a vehicle, Fig. 2 a schematic flowchart of a method for calibrating a vehicle, Fig. 3 a schematic flowchart of a method according to the invention for monitoring a calibration state, Fig. 4 a schematic flowchart of a method according to the invention in a further embodiment, Fig. 5 a schematic representation of a road network and Fig. 6 a schematic block diagram of a device according to the invention.

[0076] In the following, identical reference symbols denote elements with the same or similar technical characteristics.

[0077] Fig. 1 shows a schematic flowchart of a method according to the invention for determining at least one road contact parameter FKP of a vehicle 1 (see Fig. 5 ), where the road contact parameter FKP represents a road surface and / or tire property of vehicle 1. In particular, the road contact parameter FKP can represent a degree of road wetness.

[0078] This involves defining FK at least one calibration section KA (see Fig. 5 ) in a road network 2, wherein the calibration section KA is assigned at least one section-specific value or value range of the at least one road contact parameter FKP. This value or value range can be a constant value or value range.

[0079] Following this determination of FK, it is then determined B1 whether vehicle 1 is located in the calibration section KA. For this purpose, for example, the vehicle 1's own position can be determined and compared with stored information about the spatial location of the calibration section KA, whereby this spatial information is retrieved, for example, from a storage device not shown, which may in particular be part of a server system.

[0080] If it is detected that vehicle 1 is in calibration section KA, the road contact parameter FKP is determined by evaluating at least one output signal from a vehicle sensor 3, which is generated while vehicle 1 is driving in the at least one calibration section KA. If it is determined that vehicle 1 is not in a calibration section KA, the at least one road contact parameter FKP is not determined.

[0081] The determination of FK for at least one calibration section KA can be based on design information and / or weather information and / or traffic information. This has already been explained previously. FK can also be determined by determining the road contact parameter FKP for a road section, particularly with a predetermined position and / or length, from a plurality of calibrated vehicles 1k (see Fig. 5 ) is determined, whereby this road section is designated as calibration section KA, if the road surface contact parameters FKP determined by at least a predetermined number of calibrated vehicles 1k within a predetermined time interval do not deviate from each other by more than a predetermined amount. However, if these road surface contact parameters FKP deviate from each other by more than the predetermined amount, this road section is not designated as calibration section KA.

[0082] Fig. 2 shows a schematic flowchart of a further embodiment of a method according to the invention. In contrast to the one in Fig. 1 In the illustrated embodiment, after determining B1 whether vehicle 1 is in the calibration section, BAZ determines an activation state of the calibration section KA if vehicle 1 is in the calibration section KA. Then the road surface contact parameter FKP is set as shown in Fig. 1 The determination of B2 shown is only carried out if an active state of the calibration section KA is detected. If a deactivated state of the calibration section KA is detected, the road contact parameter FKP is not determined by B2.

[0083] As previously explained, the activation state of the calibration section KA can be established depending on weather and / or traffic information. It is also possible for a calibration section KA to be activated if the road surface contact parameters FKP, determined by at least a predetermined number of calibrated vehicles (1k) within a predetermined time interval, do not deviate from each other by more than a predetermined amount.

[0084] Accordingly, a deactivated state of an activated calibration section KA can be set if certain road contact parameters FKP deviate from each other by more than a predetermined amount.

[0085] Fig. 3 shows a schematic flowchart of a calibration method according to the invention for an uncalibrated vehicle 1u (see Fig. 5 In addition to the steps of the in Fig. 1 In the described procedure, calibration K is carried out after determining B2 of the road contact parameter FKP by comparing the road contact parameter FKP determined as proposed with the section-specific value or value range of the calibration section KA and adjusting the evaluation of the output signal of the vehicle sensor 3 in such a way that the road contact parameter FKP, which is determined with adapted evaluation, does not deviate from the section-specific value or value range by more than a predetermined amount.

[0086] Fig. 4 shows a schematic flowchart of a method according to the invention for monitoring a calibration state of a calibrated vehicle 1k (see Fig. 5 ). Unlike the one in Fig. 3 In the illustrated embodiment of the method, after determining B2 the road contact parameter FKP, the calibration state is monitored U. An uncalibrated state of the calibrated vehicle is detected if the road contact parameter FKP, determined by B2, deviates from the section-specific value or range by more than a predetermined amount. A still-calibrated state of the calibrated vehicle 1k is detected if the road contact parameter FKP does not deviate from the section-specific value or range by more than a predetermined amount.

[0087] Fig. 5 Figure 1 shows a schematic diagram of a road network 2. Vehicles 1 are also depicted. The road network 2 comprises roads with lanes. Road markings are also shown.

[0088] Also shown are calibration sections KA, which are outlined by dotted lines.

[0089] Here, a first calibration section KA1 and a second calibration section KA2 are activated calibration sections KA. A third calibration section KA3 is a deactivated calibration section.

[0090] The diagram shows an uncalibrated vehicle 1u, which is located in the activated, second calibration section KA2. This vehicle 1u can, as described in the Fig. 3 The illustrated embodiment explains a road contact parameter FKP (see Fig. 3 ) by evaluating an output signal from a vehicle sensor 3 (see Fig. 6 ) determine, wherein this output signal is generated during the journey of the vehicle 1u in the second calibration section KA2, wherein then as in relation to Fig. 3 A calibration K process is explained.

[0091] Further shown are calibrated vehicles 1k. These can determine a road contact parameter FKP in the calibration section KA and various sections of the road network 2. Depending on these parameters, the road- or contact section-specific value or value range of a road contact parameter FKP can then be defined.

[0092] Fig. 6 Figure 1 shows a schematic block diagram of a device 9 according to the invention for determining at least one road contact parameter FKP, which represents a road surface and / or tire property of a vehicle 1. The device comprises at least one vehicle sensor 3 and at least one evaluation unit 4. Furthermore, the device 9 comprises at least one device 5 for detecting a defined calibration section KA in a road network 2 (see Figure 1). Fig. 5 This device 5 can include a position sensor 6 for detecting the vehicle 1's own position. Furthermore, the device 5 can include a communication device 7 for retrieving information about the location of calibration sections KA and information about the activation state of these calibration sections KA from a server device 8.

[0093] Furthermore, this device 5, which is connected to the evaluation device 4 via signals and / or data, can determine whether the vehicle 1 is located in a calibration section KA, in particular in an active or activated calibration section KA. Furthermore, the evaluation device 4 determines at least one road contact parameter FKP, such as, for example, in relation to Fig. 1 explained, by evaluating an output signal of the vehicle sensor 3, which is connected to the evaluation unit 4 in terms of signal and / or data technology, wherein this output signal is generated during the journey of the vehicle 1 in the at least one calibration section.

[0094] Furthermore, the device 9 can include a device (not shown) for determining a section-specific value or range of values ​​for the at least one road contact parameter FKP. This device can be part of the detection device 5. The evaluation device 4 can then perform the calibration K or monitoring U described above. Bezugszeichenliste

[0095] FKDetermine B1Determine B2Determine the road contact parameter BAZDetermine the activation state FKPRoad contact parameter KKalign UMonitor KAKalignment section KA1First calibration section KA2Second calibration section KA3Third calibration section 1Vehicle 1Calibrated vehicle 1Uncalibrated vehicle 2Road network 3Vehicle sensor 4Evaluation unit 5Detection unit 6Position sensor 7Communication unit 8Server unit 9Device

Claims

1. Method for determining at least one roadway contact parameter (FKP) for a vehicle (1), which parameter represents a roadway property and / or a tire property of the vehicle (1), the method comprising: • defining (FK) at least one calibration portion (KA, KA1, KA2, KA3) in a road network (2), wherein the calibration portion (KA, KA1, KA2, KA3) is assigned at least one portion-specific value or range of values of the at least one roadway contact parameter (FKP), wherein the value or range of values of the at least one roadway contact parameter (FKP) is assigned to a weight or range of weights of vehicles (1), • determining (B1) whether the vehicle (1) is located in the calibration portion (KA, KA1, KA2, KA3), • determining (B2) the at least one roadway contact parameter (FKP) by evaluating at least one output signal from a vehicle sensor (3), which signal is generated while the vehicle (1) is traveling in the at least one calibration portion (KA, KA1, KA2, KA3), wherein the at least one roadway contact parameter (FKP) is compared to the portion-specific value or range of values, wherein a calibrated state of an uncalibrated vehicle (1u) is established using the weight-specific and portion-specific value or range of values, or an uncalibrated state of a calibrated vehicle (1k) is detected if the at least one roadway contact parameter (FKP) deviates from the weight-specific and portion-specific value or range of values by more than a predetermined amount.

2. Method according to claim 1, characterized in that in order to establish the calibrated state, the evaluation of the output signal is adjusted in such a way that the at least one roadway contact parameter (FKP) does not deviate from the portion-specific value or range of values by more than a predetermined amount.

3. Method according to either of claims 1 and 2, characterized in that a calibrated state of an uncalibrated vehicle (1u) is established using portion-specific values or ranges of values from at least two mutually different calibration portions (KA, KA1, KA2, KA3).

4. Method according to any of the preceding claims, characterized in that the at least one calibration portion (KA, KA1, KA2, KA3) is defined on the basis of construction information and / or on the basis of weather information and / or on the basis of traffic information.

5. Method according to any of the preceding claims, characterized in that an activation state of a calibration portion (KA, KA1, KA2, KA3) is determined, the step of determining (B2) the at least one roadway contact parameter (FKP) by evaluating at least one output signal from a vehicle sensor (3) being carried out only if an active state of the calibration portion (KA, KA1, KA2, KA3) is detected.

6. Method according to claim 5, characterized in that the activation state of the calibration portion (KA, KA1, KA2, KA3) is adjusted on the basis of weather information and / or traffic information.

7. Method according to any of the preceding claims, characterized in that for a road portion, the at least one roadway contact parameter (FKP) is determined by a plurality of calibrated vehicles (1k), the road portion being defined as a calibration portion (KA, KA1, KA2, KA3) or the definition of the road portion as a calibration portion (KA, KA1, KA2, KA3) being maintained or a deactivated calibration portion (KA3) being activated if the roadway contact parameters (FKP) determined by at least a predetermined number of calibrated vehicles (1k) in a predetermined time interval do not deviate from each other by more than a predetermined amount, the road portion not being defined as a calibration portion (KA, KA1, KA2, KA3) or the definition of the road portion as a calibration portion (KA, KA1, KA2, KA3) not being maintained or the calibration portion (KA1, KA2) being deactivated if the roadway contact parameters (FKP) determined by at least a predetermined number of calibrated vehicles (1k) in the predetermined time interval deviate from each other by more than a predetermined amount or the number of roadway contact parameters (FKP) determined in the predetermined time interval is less than a predetermined threshold value.

8. Method according to any of the preceding claims, characterized in that for a calibration portion (KA, KA1, KA2, KA3) or a road portion not defined as a calibration portion, the portion-specific value or range of values of the at least one roadway contact parameter (FKP) is determined or updated on the basis of roadway contact parameters (FKP) determined by calibrated vehicles (1k).

9. Method according to any of the preceding claims, characterized in that the roadway contact parameter (FKP) is a roadway wetness degree.

10. Method according to any of the preceding claims, characterized in that by evaluating an output signal from at least one further vehicle sensor, the presence of a roadway boundary and / or a further vehicle is determined when the vehicle (1) is traveling in the at least one calibration portion (KA, KA1, KA2, KA3), the at least one roadway contact parameter (FKP) additionally being determined on the basis of the output signal from the further vehicle sensor.

11. Device for determining at least one roadway contact parameter (FKP) which represents a roadway property and / or tire property of a vehicle (1), the device comprising at least one vehicle sensor (3) and at least one evaluation apparatus (4), the device (9) comprising at least one apparatus (5) for detecting a defined calibration portion (KA, KA1, KA2, KA3) in a road network (2), which portion is assigned a portion-specific value or range of values of the at least one roadway contact parameter (FKP), the detection apparatus (5) determining whether the vehicle (1) is located in a calibration portion (KA, KA1, KA2, KA3), characterized in that the value or range of values of the at least one roadway contact parameter (FKP) is assigned to a weight or range of weights of vehicles (1), the evaluation apparatus (4) determining the at least one roadway contact parameter (FKP) by evaluating at least one output signal from the vehicle sensor (3), which signal is generated while the vehicle (1) is traveling in the at least one calibration portion (KA, KA1, KA2, KA3), the at least one roadway contact parameter (FKP) being compared to the portion-specific value or range of values, a calibrated state of an uncalibrated vehicle (1u) being established using the weight-specific and portion-specific value or range of values, or an uncalibrated state of a calibrated vehicle (1k) being detected if the at least one roadway contact parameter (FKP) deviates from the weight-specific and portion-specific value or range of values by more than a predetermined amount.