Method for determining quantity characterizing friction between vehicle wheel and ground, and vehicle

Abstract

To provide a method for using an electronic computing device (17) to determine at least one quantity (49) that characterizes the current friction between a vehicle wheel (2) of a vehicle (1) and a current ground surface (5).SOLUTION: In the method, the electronic computing device (17) is used to determine at least one actual torque value (46), which characterizes an actual steering moment acting in a steering device (24) of the vehicle (1). At least one actual angle value characterizing a current roll angle of the vehicle (1) is determined. At least one actual speed value is determined characterizing a current traveling speed of the vehicle (1) and forming an actual value pair with the associated actual angle value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for determining at least one quantity characterizing the current friction between vehicle wheels of a vehicle and a current ground surface.Furthermore, the present invention relates to a vehicle. [Background technology]

[0002] US 2022 / 0126833 A1 discloses a method for receiving road friction coefficient information indicative of road friction estimates for a number of regions surrounding a vehicle. US 10773725 A1 discloses a method for determining an image of a roadway arranged in front of the vehicle with the aid of sensors of the vehicle. From US 2018 / 0037234 A1 it is known how to determine a known coefficient of friction of the wheels of the vehicle with respect to the underlying surface. Furthermore, DE 102009002245 A1 discloses a method for determining the coefficient of friction between the tires of a vehicle and the roadway. EP 2290318 A1 discloses a tilting vehicle. From DE 102019210807 A1 it is further known a steering system for a vehicle with at least one sensor for determining the steering moment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2022 / 0126833 [Patent Document 2] U.S. Pat. No. 1,077,3725 [Patent Document 3] US Patent Application Publication No. 2018 / 0037234 [Patent Document 4] DE 102009002245 A1 [Patent Document 5] European Patent No. 2290318 [Patent Document 6] DE 102019210807 Summary of the Invention [Problem to be solved by the invention]

[0004] It is an object of the invention to provide a method and a vehicle with which at least one quantity characterizing the current friction between the vehicle wheels of a vehicle and the current ground surface can be determined in a particularly advantageous manner. [Means for solving the problem]

[0005] This problem is solved according to the invention by a method having the features of claim 1 and by a vehicle having the features of claim 10. Advantageous embodiments of the invention are subject of the dependent claims.

[0006] A first aspect of the invention relates to a method for determining at least one, in particular a current quantity, characterizing the current friction between a vehicle wheel of a vehicle and a current ground surface, for example configured as a roadway and also referred to as ground, on which the vehicle is currently supported, in particular downwards in the vehicle height direction. The quantity includes, for example, at least one actual friction coefficient characterizing the current friction and / or at least one friction coefficient class characterizing the current friction, or the quantity is an actual friction coefficient characterizing the current friction, or the quantity is a friction coefficient class characterizing the current friction. For example, the method is carried out during the travel of a vehicle traveling along a ground surface (ground) during which the vehicle is supported on the ground, in particular downwards in the vehicle height direction, via the vehicle wheel, and thus during which the vehicle wheel is in particular in direct contact with the ground. The vehicle wheel is therefore merely a ground contact element, also referred to as a wheel, via which the vehicle is supported, in particular downwards in the vehicle height direction, during the method. The vehicle wheel includes, in particular, a rim and a tire, in particular configured separately from the rim, which is fitted on the rim and thus supported by the rim. In particular, the vehicle wheel is held on a component of the vehicle so as to be rotatable relative to the component about a wheel rotation axis, and in particular it is specified that during the method the vehicle wheel rolls, in particular directly on the ground surface, and in the process rotates relative to the component about the wheel rotation axis. In particular, the component is a steering element of a steering device of the vehicle, for example configured as a fork, in particular a front wheel fork, which is held on a frame so as to be rotatable relative to the frame of the vehicle, for example configured as a space frame, for example around a rotation axis, also referred to as the steering axis. Here, the vehicle wheel, for example configured as a front wheel, together with the steering element is rotatable together relative to the frame about the steering axis.

[0007] By pivoting the steering element and thus the vehicle wheels about the steering axis and relative to the frame, it is possible to steer the vehicle, and thus to make the motor vehicle turn, change direction and change lanes or roads. For example, a user of the vehicle, such as a vehicle driver, can pivot the steering element and thereby the vehicle wheels about the steering axis relative to the frame, and thus to steer the vehicle, and thus to make the motor vehicle turn, change direction and change lanes or roads.

[0008] In particular, the friction characterized by the quantity is the friction between a vehicle wheel, in particular a contact point or contact area of ​​the vehicle wheel, and a ground surface area of ​​the ground surface, with which the vehicle wheel is in particular in direct contact at a contact point or contact area, the ground surface area extending in particular on the ground surface, also called the roadway surface, which may extend perpendicularly to the vertical or at an incline.

[0009] In order to be able to determine the quantity and thus the friction in a particularly advantageous manner, it is specified according to the invention that, very preferably, at least one actual torque value acting in the steering system of the vehicle and characterizing the current steering moment, also called steering torque, is determined, i.e. indicated or determined, by means of an electronic computing device which is a component of the vehicle. In particular, for example, the steering moment is a torque acting around the steering axis. This torque acts in the steering system, for example, by a person, such as the driver of the vehicle, applying a torque, also called human moment or human torque, to the steering system, in particular to the steering element, in particular with his / her own hand, and via the steering element. For example, the steering moment is a human moment or results from a human moment. For example, the steering moment acting in the steering is detected, in particular by means of a sensor device of the vehicle. In this case, for example, the sensor device supplies, in particular an electrical sensor device signal, and for example the electronic computing device receives the sensor device signal. The sensor device signal characterizes the steering moment detected by the sensor device, so that, for example, the sensor device signal contains an actual torque value. The actual torque value is determined, for example, by the electronic computing device, by receiving the sensor device signal. It is further conceivable that the electronic computing device receives the sensor device signal and determines, in particular calculates, the actual torque value depending on the received sensor device signal.

[0010] In the method according to the invention, at least one actual angle value characterizing the actual roll angle of the vehicle is determined by means of an electronic calculation device. Roll is understood to mean the movement of the vehicle around the vehicle longitudinal axis of the vehicle, also referred to as the longitudinal axis, and the roll angle is the angle through which the vehicle is currently rolling, i.e. tilting around the longitudinal axis, in particular with respect to a starting position, also referred to as the neutral position. It is basically assumed that the current roll angle, and thus for example the actual angle value, is zero, whereby the vehicle is located in the above-mentioned starting position, or that the current roll angle is an angle different from zero by which the vehicle is currently tilted around the longitudinal axis, whereby the vehicle is currently located, for example, in an inclination position different from the neutral position, as seen around the longitudinal axis, whereby for example the actual angle value is a value different from zero. The current roll angle is calculated, for example, by means of an electronic calculation device. It is further assumed that the current roll angle is detected by means of a sensor device of the vehicle, and that the current roll angle detected by means of the sensor device is characterized by the actual angle value.

[0011] In the method according to the invention, at least one actual speed value, which characterizes the current travel speed of the vehicle, also simply referred to as speed, is determined using an electronic computing device, also referred to as a control device. In particular, the current travel speed of the vehicle, and thus for example the actual speed value, is different from 0, in particular greater than 0, so that for example during or in the method the vehicle is travelling along the ground surface at the travel speed, in particular forward. For example, the current travel speed of the vehicle is measured using a sensor device of the vehicle, so that for example the actual speed value characterizes, i.e. indicates, represents or determines, the current measured travel speed. The determined actual angle value belongs to the determined actual speed value or vice versa, so that the determined actual angle value and the determined actual speed value form an actual value pair. This does not necessarily have to be understood as the electronic computing device forming the above-mentioned actual value pairs from the actual angle values ​​and the actual speed values, i.e. the electronic computing device does not necessarily have to carry out special calculation steps in order to form the actual value pairs from the actual angle values ​​and the actual speed values ​​or to assign the actual angle values ​​and the actual speed values ​​to actual value pairs or the like, but essentially the determined actual angle values ​​and the determined actual speed values ​​are considered as values ​​forming the above-mentioned actual value pairs, this is particularly true in the case that the method can be described in a more clear and understandable manner based on the term "actual value pairs".

[0012] In the method, an electronic computing device is used to select one of the reference value pairs as a value pair belonging to the actual value pairs from at least one reference characteristic map determined for a reference friction coefficient, which comprises a number of reference angle values, a number of reference speed values ​​and a number of reference torque values ​​as a function of the actual value pairs, i.e. the actual angle value and the actual speed value, and which assigns exactly one of the reference torque values ​​to each reference value pair that comprises exactly one of the reference angle values ​​and exactly one of the reference speed values. The reference characteristic map is thus, for example, an at least or exactly three-dimensional characteristic map, which represents, so to speak, a reference torque value in relation to a reference angle value and a reference speed value. In this case, it is assumed that a number of reference value pairs are assigned to each reference torque value. It is further assumed that the same reference angle value is part of a number of reference value pairs. It is further assumed that the same reference speed value is part of a number of reference value pairs. The feature that each reference value pair contains exactly one of the reference angle values ​​and exactly one of the reference speed values, and that in particular exactly one of the reference value pairs is selected as a value pair belonging to the actual value pair, does not necessarily have to be understood as meaning that the reference value pairs, i.e. the reference angle value and the reference speed value, are actually stored and included in the reference characteristic map as reference value pairs, and the term "reference value pair" is used for the time being only in order to be able to explain the method in a clear and understandable manner below. Therefore, the feature of selecting in particular exactly one of the reference value pairs as a function of the actual value pair, i.e. the actual speed value and the actual angle value, is understood as meaning that in particular exactly one of the reference angle values ​​and in particular exactly one of the reference speed values ​​is selected as a function of the actual value pair, i.e. the actual speed value and the actual angle value, and the selected reference angle value and the selected reference speed value belong to the determined actual value pair, i.e. the determined actual angle value and the determined actual speed value, and form, for example, a merely virtual reference speed value pair.

[0013] The reference torque values ​​assigned to the selected reference value pairs are determined by means of an electronic computing device, in particular read out from a reference characteristic map, also simply referred to as characteristic map, which means that, in accordance with the selected reference angle value and the selected reference speed value, the electronic computing device determines in particular exactly one of the reference torques.

[0014] The electronic computing device is used to compare the determined reference torque value with the determined actual torque value, in other words, the electronic computing device is used to perform a comparison, in which the determined reference torque value is compared with the determined actual torque value.

[0015] The electronic computing device is used to determine a quantity depending on the comparison between the reference torque value and the actual torque value. It is further preferred that the method includes using the electronic computing device to operate, in particular for open-loop or closed-loop control, at least one component of the vehicle, i.e. at least one function of the vehicle, depending on the determined quantity.

[0016] The invention is based, inter alia, on the following findings and considerations: In many vehicle systems and driver assistance systems of a vehicle, information about the available friction coefficient or available friction coefficient class at the contact area between the vehicle wheels and the ground surface, in particular between the vehicle wheels and the ground surface, is important. This applies in particular to vehicle systems and driver assistance systems that relate to vehicle dynamics. In existing applications, the currently utilized friction coefficient or the current friction coefficient class is usually estimated, often using measured inertial quantities, including, for example, the vehicle acceleration and / or the vehicle angular velocity. However, this usually does not provide information about the currently maximally available friction coefficient or the currently maximally available friction coefficient class. For the friction coefficient, assumptions are often made or the friction coefficient is estimated by deliberately exceeding the maximally transferable tire force (limit range), for example in antilock braking systems (ABS). Another background is that the kinematics of turning and the kinematics of the steering device, also referred to as the steering system, are fundamentally different in a single-track two-wheeled vehicle, for example configured as a motorcycle, from those of a motor vehicle, for example a passenger car, in terms of the forces during turning and the torques in the steering system, also referred to simply as moments. Therefore, the methods known from the prior art that are not based on sensing the surrounding environment cannot be used to estimate the maximum coefficient of friction, for example, for a single-track two-wheeled vehicle. In contrast, the present invention makes use of the calculation, in particular the measurement, of the steering moment acting in the steering device (steering system), which acts in particular around the above-mentioned steering axis.

[0017] The invention also starts from the fact that in today's mass-produced vehicles, in particular mass-produced two-wheelers, which are constructed on a single track, information is not available about the current and preferably maximum possible coefficient of friction at the contact surface between the vehicle wheel, in particular the tire, and the ground surface, since up to now there has been no method for determining this quantity, in particular during normal driving, also called road driving. However, this coefficient of friction between the vehicle wheel and the ground surface, in particular the maximum possible coefficient of friction, can represent a quantity that can be used for improving existing safety and assistance systems and for future safety and assistance systems, in comparison with conventional solutions. The invention makes it possible, in particular, to continuously determine, in particular continuously estimate, the quantity between the vehicle wheel and the current ground surface, and thus the current friction. It is therefore preferably specified that the current maximum possible coefficient of friction between the vehicle wheel and the ground surface or the current maximum possible coefficient of friction class between the vehicle wheel and the ground surface is characterized, i.e. is shown, represented or determined, by the quantity determined by the method. In this case, the invention utilizes the steering moment, i.e. the actual torque value, and in particular, if the vehicle is preferably a single-track two-wheeler, at least one or more two-wheeler-specific characteristics. The quantities determined by the method according to the invention can, for example, be fed to at least one or more other functions of the vehicle, so that, for example, at least one other function, and thus for example the aforementioned components, can be operated depending on the determined quantities. In particular, these components or functions are, for example, warning and / or intervention functions, which are used for stabilizing the current driving state of the vehicle. An exemplary situation is the driving when driving around a curve on a test course, which typically always has a similar tilt position structure / course. If on one day the friction coefficient between the tire and the road, i.e. between the vehicle wheel and the ground surface, decreases or the friction coefficient class decreases, it may happen that this friction coefficient or friction coefficient class does not allow the tilt position that is usually driven.When this reduced coefficient of friction, in particular with respect to a normal coefficient of friction, or this reduced coefficient of friction class, in particular with respect to a normal coefficient of friction class, is recognized, the method for determining the reduced coefficient of friction and / or the reduced coefficient of friction class as a quantity or by determining the quantity is used to, for example, enable the travel of the vehicle to be assisted by at least one system of the vehicle, in particular configured as a driver assistance system, for example by reducing the vehicle speed, and / or to warn the driver of the vehicle, by outputting an indication signal, in particular haptically and / or optically and / or acoustically perceptible, by means of which the determined quantity is communicated to the driver. In particular, for example, this indication signal is output by means of an electrically operable, in particular fully electronic, reproduction device of the vehicle. Thus, for example, the reproduction device may be the component mentioned above.

[0018] The method according to the invention is further explained below on the basis of an embodiment. For example, the driver of a vehicle configured as a single-track two-wheeled vehicle supports a number of torques acting on the steering system (steering device) by means of torques, also called driver steering moments, applied by the driver to the steering system (steering device) when the vehicle is negotiating a curve and the method according to the invention is carried out, which torques act on the steering system as the above-mentioned steering moments or torques which result in steering moments acting on the steering device. The latter can act directly as torques or can result from forces acting under the corresponding lever arms. For example, when a vehicle, preferably configured as a single-track two-wheeled vehicle, travels around a curve at a first driving speed and a first roll angle, in which case the friction between the vehicle wheels and the ground surface forming the curve has a first actual value, and when, in a second curve which precedes or follows the first curve, the vehicle travels around the same curve with an equivalent first roll angle and an equivalent first driving speed, but the friction between the vehicle wheels and the ground surface has a second actual value which is different from the first actual value, the driver forms and applies to the steering system a steering moment which is different from that which was generated during the first curve, in which case the steering moment has, in the first curve, a first actual torque value, in which case the steering moment has, in which case the steering moment has, in which case the steering moment has, in which case the steering moment has, in which case the steering moment has, in which case the steering moment has, in which case the steering moment has, in which case the steering moment has, in which case the steering moment has, in which case the steering moment has, in which case the steering moment has In other words, the invention makes full use of the fact that, for equal roll angles and equal driving speeds, but with different coefficients of friction or actual values ​​of friction, the steering moment changes or must change, since both the individual torques acting on the steering system as well as the torque or steering moment components of the steering moment, in this case in particular the so-called tire torsional moment T z too 、This is because it changes when the friction coefficients are different. Tire torsional moments arise, for example, due to deformations of the tires when a vehicle, in particular configured as a single-track two-wheeler, travels in an inclined position, i.e. in particular when the roll angle or actual angle value is different from 0. This effect that different steering moments are set, i.e. acting in the steering system, for essentially the same curve maneuvers, but with or at different friction coefficients, is utilized in the method according to the invention configured as friction coefficient identification or friction coefficient calculation, in particular by determining the actual torque value, for example by measuring, i.e. detecting, the steering moment, in particular by means of a steering moment sensor of the vehicle.

[0019] The basis for the friction coefficient identification according to the invention is at least one reference characteristic map, also referred to as steering moment characteristic map. The reference characteristic map forms a known friction coefficient, for example for static curve or circular driving, configured as a high friction coefficient, in the form of a reference friction coefficient. For this friction coefficient, a reference characteristic map is determined, which is a steering torque to be set in the form of a reference steering torque value in relation to the driving speed in the form of a reference speed value and the roll angle in the form of a reference angle value. The reference characteristic map can be, for example, a M KF_μ(v,φ) where v is the driving speed, φ is the roll angle, M KF_μ stands for steering moment. The reference characteristic map may, for example, be stored in an electrical or electronic data storage device, in particular an electronic computing device. The reference characteristic map may, for example, be recorded for static and / or quasi-static circular or curved driving under defined test conditions, e.g. known coefficients of friction, pressure in the tires, also referred to as tire pressure, etc., and / or may consist of specifically calculated measurement signals determined using a validated simulation environment.

[0020] In order to be able to determine the quantity between the vehicle wheels, in particular their tires, and the ground surface, and thus the current, in particular the maximum possible friction, in one embodiment of the invention, it is specified that in order to determine the actual torque value using an electronic computing device, at least one first output value is determined using an electronic computing device, which determines at least one dynamic steering moment component acting in the steering system (steering device) and a static steering moment component acting in the steering device, whereby the first output value is, for example, a sum or represents a sum of at least one dynamic steering moment component acting in the steering device and a static steering moment component acting in the steering device. In particular, the at least one first output value represents or characterizes a static torque component and a plurality, in particular all dynamic steering moment components acting in the steering device, whereby in particular the static steering torque component and at least one dynamic steering moment component, in particular a plurality of dynamic steering torque components, as a sum, give rise to the first output value. Furthermore, for example, in order to determine the actual torque value with the aid of an electronic computing device, at least one second output value is determined with the aid of the electronic computing device in relation to the at least one dynamic steering moment component acting at the steering device and to the static steering moment component acting at the steering device, which only characterizes the at least one dynamic steering moment component acting at the steering device. To determine the actual torque value, the electronic computing device determines the actual torque value as a function of the output values, in particular by subtracting the second output value from the first output value.

[0021] In order to be able to determine the actual torque value from the output value and thus the quantity in a particularly advantageous manner, in another embodiment of the invention it is specified to calculate the second output value by means of an electronic computing device as a function of the rotational speed of the vehicle wheel and / or at least one other vehicle wheel of the vehicle, and / or the roll rate of the vehicle and / or the roll acceleration of the vehicle, and / or the steering angle rate of the vehicle, and / or the deceleration acting in particular in the longitudinal direction of the vehicle, i.e. the negative acceleration of the vehicle, and / or the pressure in at least one wheel brake of the vehicle, and / or the gyro moment, also called gyro torque, of the vehicle. For example, the rotational speed of the vehicle wheels is detected by means of a rotational speed sensor. The roll rate of the vehicle is the first time derivative of the roll angle and the roll acceleration of the vehicle is the second time derivative of the roll angle, i.e. the first time derivative of the roll rate. The yaw acceleration is in particular the second derivative of the yaw angle of the vehicle acting around the vehicle height direction of the vehicle. The deceleration of the vehicle results, for example, from braking of the vehicle. The wheel brakes are, for example, assigned to the vehicle wheels and are designed to brake the vehicle wheels and thus the motor vehicle. Thus, the wheel brakes, which are, for example, designed as friction brakes, are the service brakes of the vehicle.

[0022] Another aspect of the invention is that, in particular in real road traffic, static curve and / or circular maneuvers occur only rarely or not at all. Therefore, a quantity is determined, in particular continuously, and thus, for example, for a particularly continuous friction coefficient classification / friction identification, for example, a dynamic steering moment component is calculated from a first output value determined by measurement, i.e. by subtracting a second output value from the first output value. In particular, by subtracting the second output value from the first output value, a static value is determined, in particular calculated, and further in particular estimated, which characterizes, i.e. represents, indicates or determines, the static steering torque component in relation to at least one dynamic steering torque component and at least one static steering torque component. The static value can, for example, be a value M stationaer For example, the first output value is Mmess and the second output value is M dynamisch This means that, for example, M stationaer is M stationaer =M mess -M dynamisch In particular, M dynamisch , i.e. the second output value is a sum of a plurality of individual dynamic steering torque components or characterizes or represents this. For example, the sensor device is used to detect, i.e. measure, in particular the current steering torque, and thereby determine the first output value. For this purpose, for example, the sensor device provides a moment signal, in particular an electrical one, which characterizes the measured steering torque and thereby, for example, the first output value. The moment signal can be received by an electronic computing device, and thereby the first output value can be determined. It is further conceivable that the electronic computing device receives a moment signal and determines the first output value from or as a function of this torque signal. For example, the moment signal is a sensor device signal or a part of a sensor device signal or another signal.

[0023] The actual torque value is determined depending on the output value, for example by subtracting the second output value from the first output value, as described above. For example, the static value (M stationaer ) is used as actual torque value, which is compared with a reference torque value read out from a reference characteristic map, in particular for the measured driving speed and in particular for the measured roll angle, also called tilt angle, i.e. actual speed value and actual angle value. For example, the actual speed value is determined by measuring the driving speed. Alternatively or additionally, for example, the actual angle value is determined by measuring the roll angle. For example, the driving speed and / or the roll angle can be measured by means of a sensor device in the vehicle.

[0024] In particular, during or by means of the comparison of the reference torque value and the actual torque value, a difference between the reference torque value and the actual torque value is determined, in particular calculated. If this difference is, for example, 0, then, for example, the quantity, in particular the actual friction coefficient, is or contains the reference friction coefficient for which the reference characteristic map was determined. For example, if the actual torque value is greater than the reference torque value, for example, the difference exceeds, for example, a predefinable or preset threshold value, then it can be inferred that the quantity, in particular the actual friction coefficient, is smaller than the reference friction coefficient. However, if, for example, the actual torque value is smaller than the reference torque value, for example, the difference exceeds a threshold value and / or another threshold value, then it can be inferred that the quantity, in particular the actual friction coefficient, is larger than the reference friction coefficient. This makes it possible to advantageously determine the actual friction coefficient, in particular during the travel of the vehicle. Thus, for example, the reference friction coefficient can be understood as a reference quantity which may include at least one reference value and / or at least one reference class, or the reference quantity is a reference value or the reference quantity is a reference class.

[0025] In order to be able to determine the quantity in a particularly advantageous manner, in another embodiment of the invention, it is specified that a sensor device of the vehicle is used to detect the torque acting on the steering system, in particular the steering moment, and an actual torque value is determined as a function of the detected torque. As already explained, for example, the sensor device provides a torque signal, in particular an electric torque signal, which characterizes the torque acting on the steering system, in particular the steering moment, detected by the sensor device. For example, the moment signal is received by an electronic computing device, which determines, in particular calculates, the actual torque value as a function of the received moment signal. This allows the actual torque value, and therefore the quantity, to be determined in a particularly advantageous manner.

[0026] In order to be able to determine the quantity particularly advantageously, in another embodiment of the invention, it is specified that the first output value is determined, in particular by means of an electronic computing device, as a function of the torque detected by the sensor device. For example, the torque detected by the sensor device is characterized by the first output value, in particular, such that, for example, a moment signal comprises the first output value. Thus, for example, the electronic computing device determines the first output value, by means of the electronic computing device receiving the moment signal. It is further conceivable that the electronic computing device receives the moment signal and determines the first output value as a function of the moment signal. The actual torque value is determined, in particular calculated and thus, for example, estimated, from the output value, for example, such that the second output value is subtracted from the first output value, so that the actual torque value and the quantity can be determined particularly advantageously.

[0027] M dynamisch , i.e. the second output value is composed of, for example, individual dynamic steering moment components. In other words, for example, the second output value characterizes or represents a plurality of dynamic steering torque components. The dynamic steering moment components are calculated, for example, as a function of, in particular, measured driving dynamics variables, such as, for example, vehicle wheel rotation speeds, roll rate, roll acceleration, yaw acceleration, steering angle rate, deceleration, wheel brake pressure, etc., and also, for example, as a function of, in particular, known vehicle parameters, such as, for example, mass inertia of the vehicle wheels configured as front wheels, steering head angle, etc. The measured driving dynamics variables are, for example, appropriately filtered beforehand as a function of their respective signal quality. It is further conceivable to filter the torque, in particular the steering moment, measured by means of the sensor device, so that an actual torque value is determined as a function of the filtered torque, in particular the steering moment.

[0028] One of the important dynamic steering moment components is, for example, the wheel rotation speed ω VR of a vehicle wheel rotating at

number

number

number

number

[0029] Furthermore, one of the multiple dynamic steering moment components is

number

number

[0030] In order to be able to determine the actual torque value and thus the quantity in a particularly advantageous manner, it is furthermore necessary to provide at least one or more correction terms M korr It may be specified that the actual torque value is determined, in particular calculated, depending on a first output value, which may be configured, for example, as a measured value and is determined, in particular by measuring the torque, in particular the steering moment, and a second output value, for example a second output value (M dynamisch ) and at least one correction term M korr from the first output value to obtain a static value M station The first output value is determined, in particular by measuring the torque, in particular the steering moment, acting on the steering system, for example by means of a sensor device, so that the first output value is, for example, a measured value which characterizes the measured torque and thus the moment signal, for example being a component of the moment signal. korris, for example, a correction torque, also called a correction value, which is in particular a first output value (M mess ) is subtracted from the actual torque value or M station is M station =M mess -M dynamisch -M korr You can get 。 Correction term M korr For example, M korr_x =k x A simple first-order correction term of the form ×x. For example, the correction term M korr is, for example, denoted by x and depends, for example, on the measured driving dynamics variable, in particular on one of the driving dynamics variables denoted by x. Alternatively or additionally, for example, a correction term M korr is M korr_v_x =k v_x is a velocity-dependent correction term of the form ×v×x.

[0031] In order to be able to determine the quantity in a particularly advantageous manner, in a further embodiment of the invention it is provided that at least one position value, which characterizes at least one position of a person using the vehicle, such as the driver, relative to the vehicle, is determined by means of an electronic computing device, whereby it is advantageously provided that the actual torque value is determined as a function of the position value.

[0032] In this case, it has proven to be particularly advantageous to determine, by means of an electronic computing device, at least one influence value that characterizes the influence of the position on the current steering moment acting on the steering device of the vehicle as a function of the position value. The influence value in particular influences the steering moment component, i.e. the steering moment, and characterizes or represents or defines, for example, a dynamic torque, so that the actual torque value can be determined in a particularly advantageous manner. The background to this embodiment is that the position of the person using the vehicle relative to the vehicle, and thus for example a position change and / or a weight transfer, can result in a torque component, i.e. for example a dynamic steering moment component and / or a static steering moment component of the steering moment. It is advantageous to take this influence of the steering torque into account, so that the actual torque value can be advantageously determined. For this purpose, it is specified, for example, to subtract the steering moment component caused by the position of the person using the vehicle from the first output value. For this purpose, for example, an influence value is subtracted from the first output value.

[0033] In order to advantageously determine the position of the vehicle user relative to the vehicle and thus to be able to determine the actual torque value in a particularly advantageous manner, in another embodiment of the invention, it is specified that at least one sensor of the vehicle is used to detect a measured quantity that is influenced by the position of the vehicle user, thereby detecting the position of the person relative to the vehicle, and this position value characterizes the detected measured quantity. In other words, the position of the vehicle user relative to the vehicle is detected by a sensor that is, for example, a sensor device or a component of a sensor device, and thus this position can be detected in a particularly advantageous manner. The sensor is, for example, a force sensor and / or a pressure sensor. The sensor can be used to detect, for example, a load on the seat of the vehicle, and by detecting the load on the seat, the position of the vehicle user relative to the vehicle can be detected advantageously.

[0034] The method according to the invention is essentially intended for normal driving, also referred to as road driving, for example along a roadway configured as a road, in which a significant hang-off or hang-on driving style is not common. However, for drivers driving in this manner, the position of the driver relative to the vehicle and thus for example the upper body movements and / or the upper body position and / or the weight movement of the vehicle user are detected, in particular for example the M Fahrer It is advantageous to consider calculating an influence value M from the first output value, for example. Fahrer Therefore, M Fahrer The influence value, denoted by stationaer is M stationaer = First output value (M mess )-M dynamisch -M Fahrer It becomes.

[0035] As explained above, for example, M korr This makes it possible to determine the actual torque value and thus the quantity in a particularly advantageous manner.

[0036] Static steering moment component, i.e., the static value M stationaerFor highly dynamic driving situations, in which a particularly high accuracy of the calculation, in particular of the estimation, of is not always and easily realizable, the friction coefficient identification can, for example, be temporarily stopped, in particular until a driving state of the vehicle suitable for the friction coefficient identification is identified again via the driving situation classification. For example, measured driving dynamics signals or driving dynamics variables are used for the driving situation classification, which can be realized, for example, via a threshold-based method. For example, the friction coefficient identification can be stopped only when the vehicle is traveling straight ahead and, if necessary, at very small lean positions or roll angles below a limit. The method has also been described in relation to a person using the vehicle, such as a driver who drives and thus controls the vehicle. However, the method according to the invention can also be used to determine the steering moment and thus, for example, the first output value M mess However, it can also be applied to autonomous vehicles, such as autonomous, in particular single-track two-wheeled vehicles, in which the steering moment is set exclusively, in particular automatically, by the vehicle's systems, and / or to assisted and / or semi-autonomous vehicles, in which the steering moment consists of a steering moment set by the vehicle's systems and a steering moment set by a human being.

[0037] Finally, it has proven to be particularly advantageous if the vehicle is configured as a single-track two-wheeled vehicle, in particular a single-track motorcycle or motor cycle, in which the actual torque value and thus the amount can be determined particularly advantageously by means of the method.

[0038] A second aspect of the invention relates to a vehicle configured to carry out the method according to the first aspect of the invention. Advantageous and advantageous embodiments of the first aspect of the invention may be regarded as advantageous and advantageous configurations of the second aspect of the invention and vice versa.

[0039] Furthermore, it is also conceivable to use, for example, a second reference characteristic map, which is provided in addition to the reference characteristic map. In this case, one of the second reference value pairs is selected as the second value pair belonging to the actual value pair from a second reference characteristic map determined for a second reference friction coefficient different from the reference friction coefficient, which contains, for example, a number of second reference angle values, a number of second reference speed values ​​and a number of second reference torque values ​​depending on the actual value pairs and which assigns exactly one of the second reference torques to each second reference value pair containing exactly one of the second reference angle values ​​and exactly one of the second reference speed values. This is done, for example, by means of an electronic computing device. The second reference torque value assigned to the selected second reference value pair is determined by means of the electronic computing device. The determined second reference torque value is compared with the determined actual torque value by means of the electronic computing device. In this case, a quantity is determined depending on the comparison between the second reference torque value and the actual torque value. For example, if the actual torque value lies between the first and second reference torque values, then for example the quantity is determined, in particular calculated, and thus for example estimated, from the first and second reference friction coefficients, in particular by interpolation. Thus, for example, the current actual friction coefficient or the current friction, in particular the value, can be determined, for example, by interpolation between the two closest friction coefficients. This means, for example, that the reference torque value read out from the reference characteristic map, in particular the two reference torques read out from the reference characteristic map, which are located closest to the actual torque value, are selected, in particular the actual torque value is selected so that it lies between the selected reference torque values. In this case, for example, the quantity or the actual friction coefficient is determined from the reference friction coefficient, in particular by interpolation. For this reference friction coefficient, a reference characteristic map is determined and the closest reference torque value is read out from this reference characteristic map.

[0040] Further details of the invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings. [Brief description of the drawings]

[0041] [Figure 1]FIG. 1 is a schematic side view of a vehicle configured as a single track two-wheeled vehicle. [Diagram 2] FIG. 2 is a partial schematic perspective view of a vehicle for explaining torque. [Diagram 3] 3 is a schematic diagram showing a first reference characteristic map for explaining a method for determining at least one quantity characterizing the current friction between the vehicle wheels of a vehicle and the current ground surface; FIG. [Figure 4] FIG. 4 is a schematic diagram of a second reference characteristic map to further illustrate the method. [Diagram 5] FIG. 2 shows a flow chart to further illustrate the method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] In FIG. 1, identical or functionally equivalent elements are provided with the same reference numbers.

[0043] FIG. 1 shows a schematic side view of a vehicle 1, which is configured here as a single-track two-wheeled vehicle, in the exemplary embodiment shown in FIG. 1 as a single-track motorcycle, in particular as a single-track motor cycle. The vehicle 1 has exactly two vehicle wheels 2 and 3, which are arranged one behind the other and thus one after the other in the vehicle longitudinal direction of the vehicle. The vehicle longitudinal direction is indicated by a double arrow 4. In the exemplary embodiment shown in FIG. 1, the vehicle wheel 2 is the front wheel and the vehicle wheel 3 is the rear wheel. The vehicle wheels 2 and 3 are also simply referred to as wheels. The vehicle wheels 2 and 3 are ground contact elements of the vehicle 1, which can or are supported via the ground contact elements downwards in the vehicle height direction of the vehicle 1 on the ground 5, also referred to as the ground surface. If the vehicle 1 travels along the ground 5 while the vehicle 1 is supported downwards in the vehicle height direction of the vehicle 1 via the ground contact elements, the ground contact elements roll in particular directly on the ground 5. The vehicle height direction of the vehicle is indicated by a double arrow 6. The vehicle wheel 2 is held on a steering element 8 of the vehicle 1 rotatably about a wheel rotation axis 7 relative to the steering element 8. The steering element 8 includes a steering fork 9 and a grip 10 and is held on a frame 11 of the vehicle 1 rotatably about a rotation axis, also called steering axis L (FIG. 2). This means that the steering element 8 and also the vehicle wheel 2 together with the steering element 8 can be rotated about the steering axis L relative to the frame 11 and thus steered. This allows, inter alia, for example, for the vehicle 1 to be driven around a curve, to change direction and to change roads or lanes by a person using the vehicle 1, such as the driver of the vehicle 1. The vehicle wheel 3 is held on a swing arm 13 of the vehicle 1 rotatably about a second wheel 12 relative to the swing arm 13, also called rear wheel swing arm. The swing arm 13 itself is held on the frame 11 so as to be rotatable relative to the frame 11 around the rotation axis S, whereby the swing arm 13 and the vehicle wheel 3 are held on the frame 11 so as to be rotatable relative to the frame 11 around the rotation axis S.During straight-ahead travel of the vehicle 1, in which the vehicle 1 travels in the longitudinal direction of the vehicle, in particular forward, and in particular along a straight line, the wheel rotation axis 7 and the wheel rotation axis 12 extend parallel to one another. Furthermore, for example, the pivot axis S extends in the transverse direction of the vehicle 1, which is indicated by the double arrow 14 and extends perpendicularly to the drawing plane of FIG. 1. The vehicle 1 has, for example, a seat 15 held in the frame 11, in which a person using the vehicle 1, i.e. the driver, can sit. If reference is made above or below to a person or persons using the vehicle 1, this term is to be understood as the driver of one of the vehicles, unless otherwise specified. A person can sit on the seat 15 and can hold, in particular grab, the steering wheel 10 with his / her hands, so that via the steering wheel 10 the person can rotate the steering element 8 and by means of the steering element 8 the vehicle wheels 2 about the steering axis L relative to the frame 11. This allows the person to make the vehicle 1 turn, change direction and change lanes, and thus steer the vehicle 1. In other words again, in order to steer the vehicle 1, the steering element 8 and, together with it, the vehicle wheels 2 are rotatable about the steering axis L relative to the frame 11.

[0044] The vehicle 1 comprises an electronic calculation device 17, also referred to as a control device, by means of which a method for determining at least one quantity, also referred to as a friction coefficient quantity, is implemented, as will be explained in further more detail below, which quantity characterizes the current friction between the vehicle wheels 2 and the current ground surface 5. In the illustrated embodiment, the quantity is an actual friction coefficient or the quantity comprises at least one or exactly one actual friction coefficient, which characterizes the current friction between the vehicle wheels 2 and the current ground surface 5. If an actual friction coefficient is mentioned above or below, this term is to be understood as a quantity, unless otherwise stated.

[0045] The vehicle 1 further comprises a sensor arrangement 45, also referred to as a detection device. The sensor arrangement 45 comprises, for example, an inertial measurement technique 18, by means of which, for example, the acceleration of the vehicle 1 can be detected, for example in the vehicle transverse direction and / or in the vehicle longitudinal direction and / or in the vehicle height direction. Furthermore, for example, the roll angle of the vehicle 1 can be detected by means of the inertial measurement technique 18. Furthermore, by means of the inertial measurement technique 18, it is possible to detect the roll rate as the first time derivative of the roll angle and / or the roll acceleration as the second time derivative of the roll angle, i.e. the roll acceleration as the first time derivative of the roll rate of the vehicle 1 and / or the yaw acceleration. The sensor arrangement 45 comprises a vehicle wheel rotation speed sensor 19, also referred to simply as a rotation speed sensor, which is assigned to the vehicle wheel 2, by means of which the rotation speed of the vehicle wheel 2 around the wheel rotation axis 7 can be detected. The sensor arrangement 45 further comprises a vehicle wheel rotation speed sensor 20, also referred to simply as rotation speed sensor, which is assigned to the vehicle wheel 3, by means of which the rotation speed of the vehicle wheel 3 around the wheel rotation axis 12 can be detected. A respective wheel brake is assigned to each vehicle wheel 2, 3, for example. The respective wheel brake may be a friction brake. The respective wheel brake may in particular be configured as a respective disk brake. Particularly preferably, the respective wheel brake may be a service brake of the vehicle 1, by means of which the vehicle 1 can be braked. The sensor arrangement 45 comprises, for example, a brake pressure sensor 21, which is assigned to the wheel brake assigned to the vehicle wheel 2. The wheel brake assigned to the vehicle wheel 2 is also referred to as a first wheel brake, by means of which a first brake pressure, also referred to simply as a first pressure, can be detected in the first wheel brake.The sensor arrangement 45 further comprises a second brake pressure sensor 22, which is assigned to a wheel brake, also referred to as second wheel brake, which is assigned to the vehicle wheel 3. A second brake pressure, also referred to simply as second pressure, can be detected at the second wheel brake by means of the brake pressure sensor 22. The sensor arrangement 45 further comprises a steering moment sensor 23, by means of which a steering moment acting around the steering axis L can be detected. The steering element 8 is a component of a steering arrangement 24, also referred to as a steering system, of the vehicle 1, by means of which the vehicle 1 can be steered. The above-mentioned steering moment is a torque acting in the steering arrangement 24 (steering system), which can be detected by means of the steering moment sensor 23 of the sensor arrangement 45. The sensor arrangement 45 optionally includes a steering angle sensor 25 by means of which a respective steering angle extending around a steering axis L can be detected, and the steering element 8 can be rotated around the steering axis L relative to the frame 11 by this steering angle. In order to drive the vehicle 1 straight, the steering element 8 is located in a straight-ahead position with a steering angle of zero degrees. The sensor arrangement 45 optionally includes a steering rate sensor 26 by means of which a steering rate of the steering element 8 or of the steering device 24 can be detected. In particular, the steering rate is the first-order time derivative of the steering angle.

[0046] In FIG. 2, the vehicle 1 is shown in a partially schematic perspective view, in which forces and torques are shown. In FIG. 2, the above-mentioned steering moment is shown by the arrow 27. The arrow 28 shows the gravity force of the vehicle 1, and the arrow 29 shows the centrifugal force acting on the vehicle 1, for example when the vehicle 1 is going around a curve. The arrow 30 shows the rotation speed of the vehicle wheel 2, for example marked ω, which rotates around the wheel rotation axis 7 relative to the steering element 8, for example when going around a curve as mentioned above. The rotation speed of the vehicle wheel 2 can be detected by means of the vehicle wheel rotation speed sensor 19, also referred to simply as rotation speed sensor. The arrow 31 shows the gyro moment, also referred to as gyro torque, which acts, for example, around the vehicle longitudinal axis, also referred to simply as longitudinal axis, of the vehicle 1, in particular when going around a curve. In Fig. 2, a contact point is indicated with KP, at which the vehicle wheel 2, in particular its tire, is in particular in direct contact, i.e. in contact with the ground 5. A lateral force acting in particular on the vehicle wheel 2, in particular its tire, in the contact point KP is indicated by arrow 32, a longitudinal force acting in particular on the vehicle wheel 2, in particular at the contact point KP, is indicated by arrow 33. Arrow 34 indicates a normal force acting in particular at the contact point KP, arrow 35 indicates a T z The arrow 36 indicates the tire torsional moment, also called the rolling moment.

[0047] A first reference characteristic map 37 is shown in schematic form in Figure 3 and a second reference characteristic map 38 is shown in schematic form in Figure 4. The reference characteristic maps 37 and 38 are explained in more detail below.

[0048] In the above-mentioned method, an electronic calculation device 17 is used to determine an actual friction coefficient characterizing the current friction between the vehicle wheels 2, in particular their tires, and the current ground surface 5. The ground surface 5 being characterized as the current ground surface, i.e. the current ground surface, is understood to mean, for example, that the method is performed during a movement of the vehicle 2, which during the movement runs along the ground surface 5, during which the vehicle 2 is supported on the ground surface 5 downwards in the vehicle height direction via the ground contact elements. In particular, the movement means, for example, a curved movement in which the vehicle 1 runs through a curve, for example a right or left curve, etc., so that, for example, the vehicle 1 is in a tilting situation and thus has a roll angle different from 0 when moving and when the method is performed.

[0049] The roll angle of the vehicle 1 can be detected, for example, by means of a sensor arrangement 45, in particular by means of inertial measurement techniques 18.

[0050] In the method, the steering moment is measured by means of a sensor arrangement 45, in particular by means of a steering moment sensor 23. For example, the sensor arrangement 45, in particular the steering moment sensor 23, supplies a particularly electrical measurement signal, which is indicated by an arrow 39 in FIG. 5 and characterizes, i.e. indicates or represents, the steering moment measured by means of the sensor arrangement 45. The measurement signal 39 is filtered by means of a filter 40. The filtered measurement signal is a measured value or is indicated as a measured value or comprises at least one measured value, which is used as a first output value. The aforementioned measurement signal is also referred to as a first measurement signal. Furthermore, a driving dynamics quantity, which is in particular representative of the current driving state of the vehicle 1, i.e. the current driving dynamics, is measured by means of the sensor arrangement 45. In this case, for example, a second measurement signal, indicated by an arrow 41, is provided by the sensor arrangement 45, which is filtered by means of a second filter 42. The second measurement signal is also referred to as a driving dynamics signal. The vehicle dynamics quantities include, for example, the rotation speed of the vehicle wheels 2 and possibly also the rotation speed of the vehicle wheels 3, the roll angle of the vehicle 1, the roll rate of the vehicle 1 as the first time derivative of the roll angle, the roll acceleration of the vehicle 1 as the second time derivative of the roll angle, the yaw acceleration of the vehicle 1, the steering angle rate, the positive acceleration and / or negative acceleration acting in particular in the longitudinal direction of the vehicle 1, i.e. the deceleration of the vehicle 1, and the pressure in the wheel brakes, in particular of the vehicle wheels 2 of the vehicle 1.

[0051] In FIG. 5, the arrow 43 indicates the above-mentioned measured value, also referred to as the first output value, which in particular characterizes the steering moment, filtered by the filter 40 and detected by the steering moment sensor 17. Another of the driving dynamics variables is the current driving speed of the vehicle 1, which travels at the current driving speed along the ground 5 while the vehicle 1 is supported on the ground 5 in the vehicle height direction downwards via the ground contact element. The arrow 44 indicates an actual angle value, which represents the current roll angle of the vehicle 1, which is measured by the sensor device 45, in particular by the inertial measurement technique 18, and filtered, for example, by the filter 42. In addition, the arrow 44 indicates an actual speed value, which characterizes the current driving speed of the vehicle 1, which is measured by the sensor device 45, in particular by the inertial measurement technique 18, and filtered, for example, by the filter 42. The reference characteristic maps 37 and 38 are stored, for example, in a data storage device of the electronic computing device 17.

[0052] A current actual speed value characterizing the travel speed of the vehicle 1 detected and thus measured with the sensor arrangement 45 and a current actual angle value characterizing the roll angle of the vehicle 1 measured and thus detected with the sensor arrangement 45 form an actual measurement value pair. The first reference characteristic map 37 is determined for a first reference friction coefficient, which is, for example, 1.0. The first reference characteristic map 37 comprises a number of first reference angle values, a number of first reference speed values ​​and a number of first reference torque values. The first reference characteristic map 37 assigns exactly one of the first reference torque values ​​to each first reference value pair comprising exactly one of the first reference angle values ​​and exactly one of the first reference speed values.

[0053] The second reference characteristic map 38 is determined for a second reference friction coefficient, for example 0.5. The second reference characteristic map 38 comprises a plurality of second reference angle values, a plurality of second reference speed values ​​and a plurality of second reference torque values. The second reference characteristic map 38 assigns exactly one of the second reference torque values ​​to each second reference value pair comprising exactly one of the second reference angle values ​​and exactly one of the second reference speed values. Depending on the actual value pair, one of the first reference value pairs is selected from the first reference characteristic map 37 as a first value pair belonging to the actual value pair and depending on the actual value pair, one of the second reference value pairs is selected from the second reference characteristic map 38 as a second value pair belonging to the actual value pair. The first reference torque value assigned to the selected first reference value pair by the first reference characteristic map 37 is determined, i.e. read out, by means of the electronic calculation device 17, and the second reference torque value assigned to the selected second reference value pair is determined, i.e. read out, by means of the electronic calculation device 17, from the second reference characteristic map 38. In FIG. 5 , the static value M stationaer5 shows an actual torque value, also referred to as actual friction coefficient, which is determined, in particular calculated, by the electronic calculation device 17 from a first output value, indicated by arrow 43, and a second output value, indicated by arrow 47. In FIG. 5, a block 48 shows that a first comparison is performed by the electronic calculation device 17, in which a first reference torque value is determined and a determined actual torque value are compared. In addition, the block 48 shows that a second comparison is performed by the electronic calculation device 17, in which a second reference torque value is determined and a determined actual torque value are compared. The determined reference torque value is indicated by arrow 50. In addition, the block 48 shows that an actual friction coefficient, indicated by arrow 49 in FIG. 5, is determined by the electronic calculation device 17 as a result of the comparison. The steering moment acting on the steering device 24, measured, i.e. detected, by means of the steering moment sensor 23, is composed of at least one or exactly one static steering moment component and at least one or several dynamic steering moment components. stationaer The actual torque value, also referred to as actual torque value , characterizes, for example, the static steering moment component and at least one dynamic steering moment component exclusively, because the second output value, for example indicated by the arrow 47, characterizes at least one dynamic steering moment component, in particular the dynamic steering moment component, and is subtracted from the first output value. In FIG. 5, parameters of the vehicle 1, also referred to as vehicle parameters, are shown by block 51. Furthermore, correction factors are shown by block 52 in FIG. 5. Block 53 shows that the dynamic steering moment component is calculated by the electronic computing device 17 as a function of at least some of the driving dynamics values ​​measured by the sensor device 45 and measured, for example, by the filter 42. Furthermore, block 54 shows that a correction term, in particular as a correction torque, is calculated as a function of the correction factor and at least some of the driving dynamics values ​​measured by the sensor device 45 and filtered, for example, by the filter 42. The correction term can be, for example, M korrand the dynamic steering moment components are, for example, M dyn , where for example the correction term and the dynamic steering moment component are combined in a second output value in block 55, in particular by addition. This means, for example, that the second output value comprises the dynamic steering moment component and the correction term. In particular, the correction term and the dynamic steering moment component are combined in a second output value, for example by addition. The second output value is subtracted from the first output value, i.e. the measured value, so that the correction term and the dynamic steering moment component are calculated from the measured value (first output value). Thus, for example the actual torque value indicated by the arrow 46 characterizes the static steering moment component of the steering moment actually and currently acting on the steering device 24, which is measured with the sensor device 45 in a particularly advantageous manner. The actual friction coefficient is calculated, for example, by interpolation from the reference friction coefficient, so that the actual friction coefficient can be determined in a particularly advantageous manner. The actual friction coefficient can therefore be an estimated friction coefficient and / or can be assigned to a friction coefficient class, whereby the friction coefficient class is determined. For example, if the actual torque value is smaller than the first reference torque and larger than the second reference torque value, it can be deduced that the actual friction coefficient is smaller than the first reference friction coefficient and larger than the second reference friction coefficient, in which case the actual friction coefficient can be calculated, for example, by interpolation from the reference friction coefficient. The arrow 49 indicates that the determined, in particular calculated and even in particular estimated actual friction coefficient is an output quantity, and for example at least one component, such as at least one driver assistance system of the vehicle 1, can be operated as a function of the actual friction coefficient. With the method, the actual friction coefficient and thus the current friction can be determined in a particularly advantageous manner, so that at least one component can be operated as a function of the actual friction coefficient in a particularly advantageous manner.

[0054] For example, a large coefficient of friction, also called high μ, can be separated from a small coefficient of friction, also called low μ, when the difference, also called the distance, has a corresponding amount. Furthermore, at least two or exactly two classes may be provided, into which the coefficients of friction can be separated or assigned. [Explanation of symbols]

[0055] 1 vehicle 2 Vehicle Wheels 3 Vehicle Wheels 4. Double Arrow 5 ground 6 Double Arrow 7 Wheel rotation axis 8 Steering Elements 9. Fork 10 Handle 11 Frame 12 Wheel rotation axis 13 Swingarm 14 Double Arrow 15 sheets 17 Electronic computing equipment 18 Inertial measurement technology 19 Rotational speed sensor 20 Rotational speed sensor 21 Brake pressure sensor 22 Brake pressure sensor 23 Steering moment sensor 24 Steering Gear 25 Steering angle sensor 26 Steering rate sensor 27 Arrow 28 Arrow 29 Arrow 30 Arrow 31 Arrow 32 Arrow 33 Arrow 34 Arrow 35 Arrow 36 Arrow 37 First reference characteristic map 38 Second Reference Characteristic Map 39 Arrow 40 Filters 41 Arrow 42 Filters 43 Arrow 44 Arrow 45 Sensor Device 46 Arrow 47 Arrow 48 blocks 49 Arrow 50 Arrow 51 Block 52 blocks 53 Blocks 54 Blocks 55 blocks KP contact point L Steering axis S Rotation axis

Claims

1. A method for determining at least one quantity (49) that characterizes the current friction between the vehicle wheels (2) of a vehicle (1) and the current ground surface (5), using an electronic computer (17), - Using the aforementioned electronic computing device (17), - Determine at least one actual torque value (46) that characterizes the current steering moment acting in the steering device (24) of the vehicle (1), - Determine at least one actual angle value that characterizes the current roll angle of the vehicle (1), - Determine at least one actual speed value that characterizes and relates to the current travel speed of the vehicle (1) and forms an actual angle value and actual value pair, - Depending on the actual value pair, one of the reference value pairs is selected from at least one reference characteristic map (37) obtained for the reference friction coefficient, which includes a plurality of reference angle values, a plurality of reference speed values, and a plurality of reference torque values, and assigns exactly one of the reference torque values ​​to each reference value pair that includes exactly one of the reference angle values ​​and exactly one of the reference speed values, as the value pair belonging to the actual value pair. - Determine the reference torque value (50) assigned to the selected reference value pair, - Compare the calculated reference torque value with the calculated actual torque value (46), - The amount (49) is determined by comparing the reference torque value (50) with the actual torque value (46). A method characterized by the following:

2. In order to determine the actual torque value using the aforementioned electronic computing device (17), Using the aforementioned electronic computer (17), - Determine at least one first output value (43) that characterizes at least one dynamic steering moment component acting in the steering device (24) and a static steering moment component acting in the steering device (24), - In relation to the at least one dynamic steering moment component acting in the steering device (24) and the static steering moment component acting in the steering device (24), at least one second output value (47) is determined that characterizes only the at least one dynamic steering moment component acting in the steering device (24). - Determine the actual torque value (46) according to the first and second output values ​​(43, 47) above. The method according to claim 1, characterized in that

3. - The rotational speed of the vehicle wheel (2) and / or at least one other vehicle wheel (3) of the vehicle (1), and / or - The roll rate of the vehicle (1), and / or - The roll acceleration of the vehicle (1), and / or - The yaw acceleration of the vehicle (1), and / or, - The steering angle rate of the vehicle (1), and / or - The deceleration of the vehicle (1), and / or - Pressure in at least one wheel brake of the vehicle, and / or - Gyro moment of the vehicle (1) Accordingly, the second output value (47) is calculated using the electronic computer (17). The method according to claim 2, characterized in that

4. Using the sensor device (45) of the vehicle (1), the torque acting in the steering device (24) is detected as the steering moment, and the actual torque value (46) is determined according to the detected torque. The method according to claim 2, characterized in that

5. The first output value (43) is determined according to the torque detected using the sensor device (45). The method according to claim 4, characterized in that

6. Using the aforementioned electronic computer (17), - Determine at least one position value that characterizes the position of a person using the vehicle (1) relative to the vehicle (1), - Determine the actual torque value (46) according to the position value. The method according to claim 1, characterized in that

7. Using the aforementioned electronic computer (17), - Determine at least one influence value that characterizes the influence of the position on the current steering moment acting in the steering device (24) of the vehicle (1), according to the position value. - Determine the actual torque value (46) according to the influence value. The method according to claim 6, characterized in that

8. Using at least one sensor of the vehicle (1), a measurement quantity affected by the position of the person is detected, and the position value characterizes the detected measurement quantity. The method according to claim 6, characterized in that

9. The aforementioned vehicle (1) is configured as a single-track, two-wheeled vehicle. The method according to claim 1, characterized in that

10. A vehicle (1) configured to carry out the method described in any one of claims 1 to 9.

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