DE102021130866A1 - Method for determining a vehicle mass of a vehicle, mass estimation unit and vehicle - Google Patents

Abstract

The invention relates to a method for determining a vehicle mass, the vehicle (1) being accelerated with a driving force and a driving power, a mean mass value characterizing the vehicle mass (M) being calculated from a plurality of individual mass values, with a mass -Individual value- follows from a determined drive force value and a simultaneously determined first acceleration value, or- from a determined drive power value and a simultaneously determined speed value the speed value is corrected with a correction factor, which is determined as a function of a deviation between the first acceleration value and a second acceleration value determined at the same time, and/or the driving force value is corrected with a force correction value that is dependent on a slope force (FH) acting on the vehicle (1) at the same time, and/or the individual mass values are each weighted with a first or second quality factor, which increases the accuracy of the driving force value or the driving power value indicate.

Description

The invention relates to a method for determining a vehicle mass of a vehicle, in particular a commercial vehicle, a mass estimation unit for carrying out the method, and a vehicle with such a mass estimation unit.

In the central processing unit of an electronic brake system of a vehicle, in particular a commercial vehicle, there is an algorithm for estimating the vehicle mass of the entire vehicle, consisting of at least one towing vehicle and possibly at least one trailer or semi-trailer. Depending on this estimated vehicle mass, settings are made in the brake management of the electronic brake system and, in particular, decisions are made for threshold values of an RSC system (RSC, Roll Stability Control).

The vehicle mass is conventionally estimated according to Newton's second law (F = M × A), with the driving force (F) resulting, for example, from an engine torque taking into account other vehicle parameters (e.g. the effective transmission ratio) and the losses in the drive train, and the vehicle Acceleration (A) is derived from the change in wheel speed of the wheels. Since the driving force in particular, but also the acceleration, is dependent on a number of unobserved influencing factors, this determination is subject to inaccuracies.

The pamphlets EP 3 262 386 A1 , EP 3 262 385 A1 and WO2016/135317 A1 describe, for example, a method for estimating a vehicle mass using a recursive least square algorithm, with the input variables being in particular a second acceleration value of a longitudinal acceleration sensor, which characterizes the acceleration of the vehicle in the longitudinal direction, and a driving force value, which is derived from the Vehicle-driving engine torque can be used to better estimate vehicle mass using Newton's second law. In DE 60 2004 003 387 T2 the consideration of an inclination when determining the vehicle mass via the recursive least square algorithm is also described.

Also in DE 10 2017 129 828 A1 , EP 3 019 379 B1 , EP 3 077 781 A1 , DE 42 28 413 A1 the vehicle mass is estimated using an acceleration value that characterizes the longitudinal acceleration of the vehicle and the drive force value calculated from the engine torque. In EP 3 501 924 A1 the driving force value is determined using signals from a wheel torque sensor. In DE 197 28 769 A1 provision is made for determining the mass via drive force values and acceleration values that are present when the clutch is open and closed, with mass determination based on the individual values not being permitted in the event of excessive drive slip.

In EP 2 502 759 B1 wheel speeds of the vehicle's wheels are still used in order to determine the vehicle mass. Wheel acceleration information or first acceleration values are determined in order to subsequently determine a frequency characteristic from which the vehicle mass is then estimated.

In EP 1 951 534 B1 a load or a change in the load on the vehicle is recognized by analyzing the rotational behavior of the wheels. For this purpose, in a frequency analysis, parameters are used that are related to a natural frequency of the respective wheel and these frequency-dependent parameters are evaluated in order to draw conclusions about the load or a load change.

In DE 10 2016 200 778 A1 The loading status of the vehicle is also determined, with a tire pressure-sensitive parameter that characterizes the current loading status being determined from the wheel rotation behavior. The parameter follows from the frequency spectrum, which is determined from the wheel speed of the respective wheel.

In DE 10 2013 008 839 A1 it is also provided that a speed of the motor vehicle and a drive power of the motor vehicle are determined and the mass of the motor vehicle is determined from the speed and the drive power, for example via the power rate, according to which the sum of all powers acting on a system is equal to the change over time at any time is the kinetic energy of the system.

The object of the invention is therefore to specify a method for estimating a vehicle mass of a vehicle, with which the vehicle mass can be estimated easily and precisely. The object of the invention is also to specify a mass estimation unit and a vehicle.

This object is solved by a method, a mass estimation unit and a vehicle according to the independent claims. The dependent claims indicate preferred developments.

• - ein Antriebskraft-Wert und/oder ein Antriebsleistungs-Wert in Abhängigkeit des Motordrehmomentes ermittelt wird, wobei der Antriebskraft-Wert die Antriebskraft und der Antriebsleistungs-Wert die Antriebsleistung charakterisieren;
• - ein erster Beschleunigungs-Wert in Abhängigkeit von Raddrehzahlen von Rädern des Fahrzeuges und/oder ein Geschwindigkeits-Wert, vorzugsweise ebenfalls in Abhängigkeit der Raddrehzahlen, ermittelt wird;
• - ein Masse-Mittelwert aus mehreren Masse-Einzelwerten berechnet wird, wobei der Masse-Mittelwert die Fahrzeugmasse charakterisiert und ein Masse-Einzelwert
• - aus einem ermittelten Antriebskraft-Wert und einem zeitgleich ermittelten ersten Beschleunigungs-Wert oder
• - aus einem Antriebsleistungs-Wert und einem zeitgleich ermittelten Geschwindigkeits-Wert folgt.

The starting point is a method for determining a vehicle mass of a vehicle, with a drive for generating an engine torque, the vehicle being accelerated in a longitudinal direction with a vehicle acceleration due to the engine torque with a drive force and a drive power, with a movement of the vehicle ongoing

• - A driving force value and/or a driving power value is determined as a function of the engine torque, the driving force value characterizing the driving force and the driving power value characterizing the driving power;
• - a first acceleration value is determined as a function of the wheel speeds of wheels of the vehicle and/or a speed value, preferably also as a function of the wheel speeds;
• - a mean mass value is calculated from a plurality of individual mass values, with the mean mass value characterizing the vehicle mass and an individual mass value
• - from a determined driving force value and a simultaneously determined first acceleration value or
• - follows from a drive power value and a speed value determined at the same time.

• - der Antriebskraft-Wert zur Berechnung der Masse-Einzelwerte mit einem Kraft-Korrektur-Wert korrigiert wird, wobei der Kraft-Korrektur-Wert abhängig von einer zeitgleich auf das Fahrzeug wirkenden Hangabtriebskraft ist, und/oder
• - die Masse-Einzelwerte zur Berechnung des Masse-Mittelwertes jeweils mit einem ersten Qualitäts-Faktor oder einem zweiten Qualitäts-Faktor gewichtet werden, wobei der erste Qualitäts-Faktor eine Genauigkeit des Antriebskraft-Wertes, in Abhängigkeit dessen der jeweilige Masse-Einzelwert berechnet wird, angibt und der zweite Qualitäts-Faktor eine Genauigkeit des Antriebsleistungs-Wertes, in Abhängigkeit dessen der jeweilige Masse-Einzelwert berechnet wird, angibt.

Using a first acceleration value determined from the wheel speeds, which normally characterizes the vehicle acceleration, and/or the speed value, which normally characterizes the vehicle speed, the vehicle mass is calculated, preferably according to Newton's laws and/or according to a Estimated power rate or an energy consideration, whereby according to the power rate the sum of all powers acting on a system at any time is equal to the change in the kinetic energy of the system over time. Since, due to a number of influencing factors, it cannot always be assumed that the wheel accelerations of the individual wheels of the vehicle can be used to derive the correct vehicle acceleration or vehicle speed, the invention provides that - the first acceleration value and/or the The speed value for calculating the individual mass values is corrected with a correction factor, the correction factor being determined as a function of a deviation between the first acceleration value and a second acceleration value determined at the same time, the second acceleration value characterizing the vehicle acceleration and is determined independently of the wheel speeds, ie in a different way or based on other measured variables than is the case with the first acceleration value and/or the speed value, and/or

• - the driving force value for calculating the individual mass values is corrected with a force correction value, the force correction value being dependent on a downhill gradient force acting on the vehicle at the same time, and/or
• - the individual mass values for calculating the mean mass value are each weighted with a first quality factor or a second quality factor, the first quality factor being an accuracy of the drive force value, as a function of which the respective individual mass value is calculated , indicates and the second quality factor indicates an accuracy of the drive power value, as a function of which the respective individual mass value is calculated.

Furthermore, a mass estimation unit and a vehicle with such a mass estimation unit for carrying out the method according to the invention are also provided.

According to the invention, it is therefore recognized that the determination of the vehicle mass based on the wheel accelerations (first acceleration value) and the drive force (drive force value) or on the vehicle speed (speed value) and the drive power (drive power value) may is error-prone and therefore, if deviations are present, corresponding corrections must be made in the calculation in order to improve the quality or the accuracy of the calculation of the vehicle mass. In the present case, this can be done in that the determined vehicle acceleration (first acceleration value) and/or the determined driving force (driving force value) and/or the determined average drive power (drive power value) are checked for plausibility and the following deviations in the respective factors are taken into account from this plausibility check. In this way, influences on the wheel rotation behavior that are not caused by acceleration of the vehicle as a result of the engine torque generated can be taken into account.

By resorting to the ascertained factors, with which deviations can ideally be compensated for, the vehicle mass can then advantageously also continue to be based on the ascertained first acceleration value or the ascertained drive force value or the ascertained speed value or the ascertained drive power value. value can be calculated with a high degree of accuracy, so that no fundamental adjustments need to be made when determining the mass. This also makes it easier to retrofit or adapt.

It is preferably also provided that the second acceleration value is determined by a longitudinal acceleration sensor in the vehicle, which can be part of an EBS system in the vehicle, for example, at the same time as the first acceleration value, with the correction factor depending on a deviation between the first acceleration value and the second acceleration value is defined in such a way that the deviation is compensated for when the first acceleration value is corrected with the correction factor.

Advantageously, the acceleration value determined via the wheel speeds can be checked for plausibility by resorting to a vehicle acceleration measured elsewhere or redundantly (cf. diverse redundancy) by the longitudinal acceleration sensor, with a longitudinal acceleration sensor of the EBS system already present in the vehicle being used for this purpose. The longitudinal acceleration sensor is only used for the plausibility check or for determining the deviation, and the resulting factor is used continuously to correct future first acceleration values and/or speed values from the wheel speeds. In this case, the longitudinal acceleration sensor can be read out with an update frequency which, in the event of decisive changes in the roadway gradient here, enables a timely correction via the correction factor.

Provision is preferably also made for the correction of the first acceleration value and/or the speed value to take place using the correction factor if the absolute value of the deviation is above a deviation limit value of 10%, for example. In this way, a correction can be avoided in the case of minimal deviations that can be attributed to measurement inaccuracies, for example.

It is preferably also provided that the correction factor and/or the deviation for determining the correction factor is determined when an angle of inclination of a roadway on which the vehicle is moving is zero. In this way, influences on the second acceleration value, which are caused by a downhill slope force, can be avoided.

It is preferably also provided that the angle of inclination is determined as a function of the second acceleration value of the longitudinal acceleration sensor. For example, at a constant driving speed, i.e. with a vehicle acceleration of zero, it can be checked whether the second acceleration value deviates from the first acceleration value, which should ideally be zero in this case. A deviation can then be attributed to the fact that a downhill slope force component acts, which only has an influence on the second acceleration value determined by the longitudinal acceleration sensor. Since the amount of the deviation results from the current slope, the angle of inclination can be deduced.

According to this procedure, the downhill slope force for determining the force correction value for correcting the driving force value for calculating the individual mass values can also be determined from the second acceleration value and/or from the angle of inclination. Accordingly, the driving force can also be checked for plausibility and corrected accordingly in a simple manner by resorting to the measured second acceleration value from the deviation or the angle of inclination. In principle, the slope force determined in this way can also be used to determine the power loss that counteracts the drive power, in order in this way to enable the vehicle mass to be correctly determined from the drive power and the speed value.

Provision is preferably also made for the drive force value and/or the drive power value to be determined as a function of losses in a drive train of the vehicle. can Losses due to the vehicle body or the design of the drive train are estimated, for example, and are taken into account accordingly in order to improve the quality and accuracy of the mass determination.

• - MWi = FW/(AW1 × K), wenn der erste Beschleunigungs-Wert mit dem Korrektur-Faktor korrigiert wird, und/oder
• - MWi = (FW - FKW)/(AW1), wenn der Antriebskraft-Wert mit einem Kraft-Korrektur-Wert korrigiert wird. Demnach werden mathematische Zusammenhänge, die auf die Newtonschen Gesetze zurückzuführen sind, angewandt, die es auch weiterhin ermöglichen, die Masseermittlung ausgehend von dem ermittelten Raddrehverhalten (erster Beschleunigungs-Wert) bzw. Antriebsverhalten des Fahrzeuges (Antriebskraft-Wert) durchzuführen.

Provision is preferably also made for the individual mass values to be determined for the respective point in time from

• - MWi = FW/(AW1 × K), if the first acceleration value is corrected with the correction factor, and/or
• - MWi = (FW - FKW)/(AW1) when the driving force value is corrected with a force correction value. Accordingly, mathematical relationships that can be traced back to Newton's laws are applied, which continue to make it possible to carry out the mass determination based on the determined wheel rotation behavior (first acceleration value) or drive behavior of the vehicle (driving force value).

It is preferably also provided that the individual mass values are determined from speed values at two different points in time and drive power values for these two points in time, with the two points in time being selected in such a way that a total driving resistance assigned to the points in time, which composed, for example, of the sum of rolling resistance, air resistance and gradient resistance, does not change significantly between the two points in time, with this total driving resistance determining a power loss as a function of speed, which counteracts the drive power. In this way, almost constant driving resistances do not have to be taken into account when estimating the vehicle mass, which simplifies the mass estimation. In addition, taking such driving resistances into account can lead to the mass determination becoming even more imprecise, e.g. if the methods used to determine the driving resistances are subject to inaccuracies.

Provision is preferably also made for the speed values for the two different points in time to be corrected as a function of the correction factor, for example by mathematically integrating the correction factor determined from the vehicle acceleration. Equally effective, however, a diverse determination of the vehicle speed can also be used if, for example, the vehicle speed is not determined directly or indirectly from the wheel speeds.

• - erste Wertepaare aus einem Antriebsschlupf zwischen Vorderrädern und Hinterrädern des Fahrzeuges und einem zeitgleich vorliegenden erster Antriebskraft-Wert und/oder
• - zweite Wertepaare aus dem Antriebsschlupf zwischen den Vorderrädern und den Hinterrädern des Fahrzeuges und einem zeitgleich vorliegenden Antriebsleistungs-Wert gebildet werden, wobei
• - aus den ersten Wertepaaren eine erste Regressionsgerade und/oder aus den zweiten Wertepaaren eine zweite Regressionsgerade ermittelt wird und
• - für jedes erste Wertepaar ein erster Werte-Abstand zwischen dem ersten Wertepaar und der erste Regressionsgerade und/oder
• - für jedes zweite Wertepaar ein zweiter Werte-Abstand zwischen dem zweiten Wertepaar und der zweiten Regressionsgerade bestimmt wird, wobei
• - dem ersten Wertepaar der erste Qualitäts-Faktor in Abhängigkeit seines ersten Werte-Abstandes und/oder
• - dem zweiten Wertepaar ein zweiter Qualitäts-Faktor in Abhängigkeit seines zweiten Werte-Abstandes zugeordnet wird, und der jeweilige Masse-Einzelwert,
• - der aus dem Antriebskraft-Wert des jeweiligen ersten Wertepaares folgt, mit dem diesem ersten Wertepaar zugeordneten ersten Qualitäts-Faktor gewichtet wird und/oder
• - der aus dem Antriebsleistungs-Wert des jeweiligen zweiten Wertepaares folgt, mit dem diesem zweiten Wertepaar zugeordneten zweiten Qualitäts-Faktor gewichtet wird.

It is preferably also provided that the individual mass values that result from the drive force value are multiplied by the respective first quality factor and the individual mass values that result from the drive power value are multiplied by the respective second quality factor become. This makes it possible to weight the individual mass values determined at the respective point in time independently of one another. It is preferably provided that continuously

• - first pairs of values from a drive slip between the front wheels and rear wheels of the vehicle and a first driving force value that is present at the same time and/or
• second pairs of values are formed from the drive slip between the front wheels and the rear wheels of the vehicle and a drive power value that is present at the same time, with
• - a first regression line is determined from the first pairs of values and/or a second regression line is determined from the second pairs of values and
• - for each first pair of values, a first value distance between the first pair of values and the first regression line and/or
• - for each second pair of values, a second value distance between the second pair of values and the second regression line is determined, where
• - the first pair of values, the first quality factor depending on its first value difference and/or
• - a second quality factor is assigned to the second pair of values depending on its second value distance, and the respective individual mass value,
• - which follows from the driving force value of the respective first pair of values, is weighted with the first quality factor assigned to this first pair of values and/or
• - which follows from the drive power value of the respective second pair of values, is weighted with the second quality factor assigned to this second pair of values.

Therefore, a deviation can easily be determined or a plausibility check of the determined drive force values or the drive power values are carried out. Depending on the level of the deviation or the quality of the driving force values or the driving power values with regard to this respective regression line, the weighting can then take place so that the driving force value or the driving power value can also be checked for plausibility and corrected in a simple manner can be.

It is preferably also provided that the drive slip is adjusted to zero in a freely rolling manner and the regression line is thus defined in such a way that it runs through the origin. As a result, the regression line can be defined by a point already determined by the theory.

• 1 eine schematische Ansicht eines Fahrzeuges;
• 2a ein Schlupf-Diagramm zum Plausibilisieren eines Antriebskraft-Wertes;
• 2b ein Schlupf-Diagramm zum Plausibilisieren eines Antriebsleistungs-Wertes; und
• 3 ein Flussdiagramm des erfindungsgemäßen Verfahrens.

The invention is explained in more detail below with reference to figures. Show it:

• 1 a schematic view of a vehicle;
• 2a a slip diagram for plausibility checking of a driving force value;
• 2 B a slip diagram for plausibility checking of a drive power value; and
• 3 a flowchart of the method according to the invention.

1 shows a highly schematic vehicle 1, which consists of a towing vehicle 1a and a trailer 1b. However, the vehicle 1 can in principle also be a one-piece vehicle or, as a multi-piece vehicle, consist of a towing vehicle 1a with one or more trailers (drawbar trailers, etc.) or semi-trailers 1b. The vehicle 1 has an electronic braking system 2 (EBS) which, in the case of a two-part vehicle, can be divided into a towing vehicle braking system and a trailer braking system. The electronic brake system 2 has a central module 3 that controls the electronic brake system 2 in a conventional manner in order to brake the vehicle 1 accordingly, for example by activating various assistance functions (ESC, RSC, ABS, ASR, etc.).

The vehicle 1 also has a mass estimation unit 4 which is arranged, for example, in the towing vehicle 1a and is designed to estimate the vehicle mass M of the vehicle 1 and to output a corresponding estimated estimated mass value MW. The vehicle mass M here relates to the entire vehicle 1 from any vehicle parts (traction vehicle 1a and semi-trailer 1b or other trailers/semi-trailers). The mass estimation unit 4 can be integrated, for example, in the central module 3 of the electronic braking system 2, for example as software, so that the estimated mass value MW can be generated directly in the central module 3, in particular for consideration in the respective assistance functions. Equally effective, the mass estimation unit 4 can also be connected to the central module 3 in a signal-conducting manner, so that the estimated mass value MW can be transmitted to the central module 3 from the outside.

According to a first embodiment, the mass estimation unit 4 estimates the vehicle mass M on the basis of Newton's second law F=M×A, where F is a driving force with which the vehicle 1 is driven in order to drive the vehicle mass M with a longitudinal direction L of the vehicle 1 oriented vehicle acceleration A to accelerate. The drive force F results, for example, from an engine torque D generated by the drive 50 of the vehicle 1, taking into account losses AV that normally occur in a drive train 55 of the vehicle 1. The engine torque D or a variable associated therewith can be transmitted to the mass estimation unit 4 by a drive controller 51 (engine electronics) of the drive 50, for example via a data bus of the vehicle 1. Depending on this, the latter can determine a drive force value FW, which characterizes the drive force F, taking into account the losses AV in the drive train 55 .

Vehicle acceleration A can be characterized by a first acceleration value AW1, which results, for example, as a function of calculated wheel accelerations A5 of individual wheels 5 of vehicle 1. For this purpose, the wheel speeds N are determined wheel-specifically by wheel speed sensors 6 on the respective wheels 5 of the vehicle 1 and, from this, the individual wheel accelerations A5 calculated. The vehicle acceleration A or the first acceleration value AW1 then follows, for example by forming an average value over all or some wheels 5.

The vehicle mass M is estimated in the mass estimation unit 4 according to the first embodiment, for example, by continuously using the formula M=F/A to calculate individual mass values MWi=FW/AW1, with i=1, 2, 3, . . . p (p=number of individual values) can be calculated for the currently available acceleration or drive force values AW1, FW. A mean mass value MWM (arithmetic mean) is then formed from the individual mass values MWi determined at different points in time t, the mean mass value MWM indicating the estimated mass value MW to be output. As a result of the averaging, the estimated mass value MW approaches the actual vehicle mass M of the vehicle 1 as the number p of individual mass values MWi increases.

According to a second embodiment, the mass estimation unit 4 can also determine the vehicle mass M on the basis of a power rate or an energy balance. Accordingly, it is taken into account that the sum of all powers acting on a system, in this case a drive power PA and a power loss PV, is equal to a change dt over time in a kinetic energy Ekin of the system at any point in time t. This can be expressed by the formula (d/dt)Ekin = PA - PV, where (d/dt) denotes the time derivative.

The drive power PA results from the engine torque D, with the engine torque D or a variable associated therewith being able to be transmitted from the drive controller 51 (engine electronics) of the drive 50, for example via a data bus of the vehicle 1, to the mass estimation unit 4. If a corresponding sensor system is present in the vehicle 1, via which, for example, a rolling resistance FR, an air resistance FL and a gradient resistance FSt can be determined as individual driving resistances (corresponding to a force), which each counteract the drive power PA, the power loss PV can also be estimated directly become. The power loss PV is dependent on the speed, i.e. from a speed value VW, which is present at time t, and a total driving resistance FV, which acts on vehicle 1 at the same time t and which is the sum of the individual driving resistances mentioned above FR, FL, FSt results.

wobei V eine Fahrzeug-Geschwindigkeit des Fahrzeuges 1, J ein Trägheitsmoment und ω eine Winkelgeschwindigkeit angeben. Demnach setzt sich die kinetische Energie Ekin aus einem Translations-Anteil ET = ½ * M * V² und einem Rotations-Anteil ER = ½ * J * ω² zusammen. Wird dieser Zusammenhang für die kinetische Energie Ekin mit dem o.g. Leistungssatz verknüpft, ergibt sich nach entsprechender Umstellung: $$\left(\text{d/dt}\right)\text{ET}=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.*\text{M*}\left(\text{d/dt}\right){\text{V}}^2=\text{PA}-\text{FV*V}-\left(\text{d/dt}\right)\text{ER}$$

At the same time, the following applies to the kinetic energy of the system: $$\text{Ekin}=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.*{\text{M*V}}^2+\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.*\text{Y*}{\mathrm{\omega }}^2=\text{ET}+\text{HE}\text{,}$$

where V indicates a vehicle speed of the vehicle 1, J indicates a moment of inertia, and ω indicates an angular velocity. According to this, the kinetic energy Ekin consists of a translation part ET = ½ * M * V ² and a rotational part ER = ½ * J * ω ² . If this relationship for the kinetic energy Ekin is linked to the above power rate, the result after appropriate conversion is: $$\left(\text{d/dt}\right)\text{ET}=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.*\text{M*}\left(\text{d/dt}\right){\text{<figure-callout id="2" label="V" filenames="DE102021130866A1\_0008.png" state="{{state}}">V</figure-callout>}}^2=\text{PA}-\text{FV*V}-\left(\text{d/dt}\right)\text{HE}$$

$$\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.*\text{M*}\left(\text{d/dt}\right){\text{V2}}^2=\text{PA2}-\text{FV*V2}-\left(\text{d/dt}\right)\text{ER2}\text{,}$$

wobei „V1“ durch den Geschwindigkeits-Wert VW bei t=t1, „PA1" durch den Antriebsleistungs-Wert PA bei t=t1 und „ER1“ durch den Rotations-Anteil ER bei t=t1 gegeben sind, und „V2“ durch den Geschwindigkeits-Wert VW bei t=t2, „PA2“ durch den Antriebsleistungs-Wert PA bei t=t2 und „ER2“ durch den Rotations-Anteil ER bei t=t2 gegeben sind. Wird die erste Gleichung in die zweite Gleichung eingesetzt (aufgelöst nach dem in etwa identischen Gesamt-Fahrwiderstand FV), ergibt sich in guter Näherung: $$\text{M}=2*\left[\text{PA1}-\left(\text{d/dt}\right)\text{ER1}-\left(\text{V2/V1}\right)\left(\text{PA2}-\left(\text{d/dt}\right)\text{ER2}\right)\right]/\left[\left(\text{d/dt}\right){\text{V1}}^2-\left(\text{V2/V1}\right)\left(\text{d/dt}\right){\text{V2}}^2\right]$$

If the power loss PV or the total driving resistance FV is known, this equation can be rearranged based on the vehicle mass M. However, if the power loss PV or the total driving resistance FV is not known, the energy or the power is considered at two points in time t that follow each other briefly, a first point in time t1 and a second point in time t2. In this case, it can be assumed as a good approximation that the total driving resistance FV, which determines the power loss PV as a function of speed, does not change significantly between times t1, t2. The above equation for both points in time t1, t2 is then as follows: $$\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.*\text{M*}\left(\text{d/dt}\right)\text{<figure-callout id="1" label="V" filenames="DE102021130866A1\_0008.png" state="{{state}}">V</figure-callout>}{1}^2=\text{PA1}-\text{FV*V1}-\left(\text{d/dt}\right)\text{ER1}$$

$$\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.*\text{M*}\left(\text{d/dt}\right){\text{v2}}^2=\text{PA2}-\text{FV*V2}-\left(\text{d/dt}\right)\text{ER2}\text{,}$$

where "V1" is given by the speed value VW at t=t1, "PA1" by the drive power value PA at t=t1 and "ER1" by the rotation component ER at t=t1, and "V2" by the speed value VW at t=t2, "PA2" by the drive power value PA at t=t2 and "ER2" by the rotation component ER at t=t2. If the first equation is inserted into the second equation ( resolved according to the approximately identical total driving resistance FV), the result is a good approximation: $$\text{M}=2*\left[\text{PA1}-\left(\text{d/dt}\right)\text{ER1}-\left(\text{V2/V1}\right)\left(\text{PA2}-\left(\text{d/dt}\right)\text{ER2}\right)\right]/\left[\left(\text{d/dt}\right){\text{<figure-callout id="2" label="V1" filenames="DE102021130866A1\_0008.png" state="{{state}}">V1</figure-callout>}}^2-\left(\text{V2/V1}\right)\left(\text{d/dt}\right){\text{v2}}^2\right]$$

Since the respective parameters in this formula are known at the respective points in time t1, t2 from corresponding measurements in the vehicle 1 or can be provided in some other way, the vehicle mass M can be estimated using this formula. The speed value VW at the respective point in time t=t1,t2 can be determined, for example, as a function of the wheel accelerations A5 of the individual wheels 5 of the vehicle 1 calculated above, by mathematical integration or, with the same effect, also directly from the wheel speed sensors 6 on the respective wheels 5 of the vehicle 1 determined wheel speeds N derive.

The vehicle mass M is then estimated in the mass estimation unit 4 according to the second embodiment, for example, by continuously using the above formula M=2*[PA1-(d/dt)ER1-(V2/V1)(PA2-(d/ dt)ER2)] / [(d/dt)V1 ² -(V2/V1)(d/dt)V2 ² ] Individual mass values MWi, with i = 1, 2, 3, ... p (p = number on individual values) are calculated. A mean mass value MWM (arithmetic mean) is then formed from the individually determined individual mass values MWi, the mean mass value MWM indicating the estimated mass value MW to be output. As a result of the averaging, the estimated mass value MW approaches the actual vehicle mass M of the vehicle 1 as the number p of individual mass values MWi increases.

• So ist gemäß einer Ausführung vorgesehen, auf einen Längsbeschleunigungssensor 7 im Fahrzeug 1 zurückzugreifen, der die in Längsrichtung L des Fahrzeuges 1 orientierte Fahrzeug-Beschleunigung A direkt misst und in Abhängigkeit davon einen zweiten Beschleunigungs-Wert AW2 erzeugt und ausgibt. Dieser zweite Beschleunigungs-Wert AW2 sollte im Idealfall dem zum selben Zeitpunkt t ermittelten ersten Beschleunigungs-Wert AW1 (aus den Radbeschleunigungen A5) entsprechen.

According to the invention, when calculating the vehicle mass M using the formula M=F/A (first embodiment) or M=2*[PA1-(d/dt)ER1-(V2/V1)(PA2-(d/dt)ER2) ] / [(d/dt)V1 ² -(V2/V1)(d/dt)V2 ² ] (second embodiment) made the following additions in order to make the estimation of the vehicle mass M or the estimated mass value MW more precise:

• According to one embodiment, a longitudinal acceleration sensor 7 in the vehicle 1 is used, which directly measures the vehicle acceleration A oriented in the longitudinal direction L of the vehicle 1 and generates and outputs a second acceleration value AW2 as a function of this. In the ideal case, this second acceleration value AW2 should correspond to the first acceleration value AW1 (from the wheel accelerations A5) determined at the same point in time t.

Depending on the second acceleration value AW2, an inclination angle NW can be estimated according to the current gradient (uphill, downhill) of a roadway 10 on which the vehicle 1 is moving. For this purpose, at a constant vehicle speed V, i.e. at a vehicle acceleration of A=0, it is checked whether the second acceleration value AW2 deviates from the first acceleration value AW1, which should ideally be zero, with a deviation being attributable to this is that a downhill slope force component acts, which only has an influence on the second acceleration value AW2 determined by the longitudinal acceleration sensor 7 . Since the amount of the deviation results from the current gradient (uphill, downhill gradient), the angle of inclination NW can be deduced. From this angle of inclination NW, a slope force FH acting parallel to the longitudinal direction L of the vehicle 1 can then be estimated, which also causes the vehicle 1 to accelerate at the relevant point in time t. When there is an incline, the vehicle mass M is therefore no longer set in motion only by the engine torque D (driving force value FW) generated by the drive 50 of the vehicle 1, but also by the downhill gradient force FH.

In order to improve the accuracy of the mass calculation according to the first embodiment using the formula M=F/A, a force correction value FKW that is dependent on the downhill force FH and influences the driving force F must also be applied for the respective point in time t. Accordingly, the formula for calculating the individual mass values MWi for estimating the vehicle mass M is adjusted in: $$\text{MWi}=\left(\text{fw}-\text{HFC}\right)/\text{AW1}\text{.}$$

In the second embodiment, the slope force FH determined in this way can be taken into account for the gradient resistance FSt, which as a driving resistance contributes to the power loss PV via the total driving resistance FV, insofar as a mass estimate is to be made taking into account the power loss PV.

Provision can furthermore be made for the first acceleration value AW1, which is determined via the wheel speeds N of the respective wheels 5, to be checked for plausibility by the second acceleration value AW2, which is output by the longitudinal acceleration sensor 7. For this purpose, at an angle of inclination NW of zero degrees, ie when driving on level ground or when no downhill force FH is acting, a Ver carried out equally between the first acceleration value AW1 and the simultaneously determined second acceleration value AW2. In the plane, the two acceleration values AW1, AW2 should roughly match. However, if there is a deviation dAW=AW1 - AW2, the absolute value of which is above a deviation limit value GAW (e.g. 10%), an incorrect determination of the first acceleration value AW1 can be concluded, for example due to incorrectly parameterized rolling circumferences of the wheels 5.

In order to compensate for this systematic error in the mass calculation, a correction factor K dependent on the deviation dAW (e.g. with a 15% upward deviation: K = 0.85) is determined, which compensates for this deviation dAW, so that the individual mass values can be calculated MWi for estimating the vehicle mass M according to the first embodiment (M=F/A), the following formula can be applied: $$\text{MWi}=\left(\text{fw}-\text{HFC}\right)/\left(\text{AW1*K}\right).$$

An intermediate variable (AW1*K) is thus determined which characterizes the actual vehicle acceleration A more precisely.

This deviation-dependent (dAW) correction factor K can also be used for the second embodiment. Since the correction factor K follows from the systematically incorrect measurement of the wheel speeds N via the wheel speed sensors 6, the vehicle speed V following from the wheel speeds N of the respective wheels 5 (directly from N or by integrating the vehicle acceleration A) or the speed value VW can be corrected as a function of this correction factor K. For this purpose, the correction factor K that follows from the deviation dAW for the vehicle acceleration A must be integrated accordingly, so that with this correction factor K or, depending on this correction factor K, the determined vehicle speed V or the speed -Value VW, which in the above formula M=2*[PA1-(d/dt)ER1-(V2/V1)(PA2-(d/dt)ER2)] / [(d/dt)V1 ² -( V2/V1)(d/dt)V2 ² ] is used, can be corrected.

In this way, a more precise mass calculation is made possible by checking the vehicle acceleration A or indirectly also the vehicle speed V and by including the incline of the roadway 10 . This eliminates or reduces influences or error sources that occur due to the angle of inclination NW of the roadway 10 or due to an incorrect or imprecise determination of the vehicle acceleration A or the vehicle speed V via the wheel speeds N of the wheels 5 .

A further improvement in the accuracy when estimating the vehicle mass M via the two embodiments mentioned can be achieved in that the driving force F or the driving force value FW and/or the driving power PA or the driving power value PAW, which follow the generated engine torque D, taking into account losses AV in the drive train 55, is or are being checked for plausibility. In the present case, this is done by determining a drive slip S between the freely rolling front wheels 5V and the driven rear wheels 5H of the vehicle 1. This drive slip S results from a comparison or from a difference between the front wheel wheel speeds NV (e.g. averaged over both front wheels 5V ) of the non-driven front wheels 5V and the rear wheel wheel speeds NH (e.g. averaged over both rear wheels 5H) of the driven rear wheels 5H, i.e. S = NH - NV.

• Im normalen Fahrbetrieb wird ein fahrzeugspezifisches Schlupf-Diagramm SD (s. 2a für die erste Ausführungsform und 2b für die zweite Ausführungsform) gebildet, das sich zusammensetzt aus mehreren Antriebskraft-Werten FW (s. 2a) oder aus mehreren Antriebsleistungs-Werten PAW (s. 2b), die jeweils zu unterschiedlichen Zeitpunkten t ermittelt wurden, und Antriebsschlüpfen S, die zeitgleich zu den jeweiligen Antriebskraft-Werten FW bzw. Antriebsleistungs-Werten PAW ermittelt wurden. Es findet also eine Zuordnung zwischen einem Antriebskraft-Wert FW und einem zeitgleich ermittelten Antriebsschlupf S oder zwischen einem Antriebsleistungs-Wert PAW und einem zeitgleich ermittelten Antriebsschlupf S statt.

It is assumed that in a driving situation without an active engine torque D (all wheels 5; 5H, 5V rolling freely), the drive slip S is zero, since ideally there should be no speed differences between the axles when rolling freely. The drive slip S is therefore initially adjusted to zero in such a driving situation. Proceeding from this, it is assumed that the drive slip S in stable driving operation changes linearly with the acting drive force F or with the acting drive power PA, which is or are transmitted to the ground via the driven rear wheels 5H. This is used as follows for a plausibility check of the drive force value FW in the first embodiment and/or the drive power value PAW in the second embodiment:

• In normal driving operation, a vehicle-specific slip diagram SD (see 2a for the first embodiment and 2 B for the second embodiment), which is composed of several driving force values FW (see 2a ) or from several drive power values PAW (s. 2 B ), which were determined at different points in time t, and drive slip S, which was determined at the same time as the respective drive force values FW or drive power values PAW the. There is therefore an association between a driving force value FW and a drive slip S determined at the same time or between a drive power value PAW and a drive slip S determined at the same time.

Such first pairs of values WP1 (S, FW) or second pairs of values WP2 (S, PAW) are determined continuously for different points in time t, this being shown in the slip diagrams SD in FIGS 2a , 2 B is shown as an example in the form of several crosses.

With these pairs of values WP1, WP2, a first or second regression line R1, R2 is continuously determined, each of which intersects the origin, with the respective regression line R1, R2 becoming more precise as the number of pairs of values WP1, WP2 determined increases. If the accuracy or number of respective value pairs WP1, WP2 is sufficiently high, the determination of the respective regression line R1, R2 can be stopped or suspended. Individual pairs of values WP1, WP2 are more or less close to the respective regression line R1, R2, as in FIGS 2a and 2 B shown. A linear course of the regression is applied here, since a linear relationship between the drive force F (FW) and the drive slip S or between the drive power PA (PAW) and the drive slip S is also assumed. Therefore, with continuous improvement of the accuracy of the respective regression line R1, R2, it can be assumed that a first value distance WA1 between a first pair of values WP1 and the first regression line R1 can be used to calculate a first quality factor Q1. Correspondingly, a second value distance WA2 between a second value pair WP2 and the second regression line R2 can be used to calculate a second quality factor Q2.

An increasing value distance WA1, WA2 to the respective regression line R1, R2 is an indicator of a higher inaccuracy of a pair of values WP1, WP2, for example due to inaccuracies in determining the drive force value FW or the drive power value PAW from the engine torque D or when estimating losses AV in the drive train 55, so that a lower quality factor Q1, Q2 can be used for this respective pair of values WP1, WP2. A driving force value FW or a driving power value PAW from an imprecise pair of values WP1, WP2 with a lower quality factor Q1, Q2 cannot be supported as a measured value by considering the drive slip S at the same point in time t. The individual mass value MWi, which contains the drive force value FW or drive power value PAW from this respective imprecise value pair WP1, WP2, is therefore not used, or only used to a reduced extent, for calculating the vehicle mass M. This allows outliers or systematic errors due to e.g. additional losses due to cold oil or other sources of error to be recognized and eliminated.

The vehicle mass M can therefore be calculated in the sense that each individual mass value MWi (determined by FW - FKW) / (AW1 *K) or (FW - FKW) / (AW1) or (FW) / (AW1 *K ) in the first embodiment or by the respective formula in the second embodiment via the power set or the energy) when determining the mean mass value MWM (arithmetic mean) is weighted with that quality factor Q1, Q2, which is for the driving force Value FW or drive power value PAW of this individual mass value MWi follows from the respective slip diagram SD. With the continuous determination of the respective regression lines R1, R2, the respective quality factor Q1, Q2 can also change for some individual mass values MWi, so that the mean mass value MWM or the estimated mass value MW also changes as the driving operation progresses and converges to the actual vehicle mass M with higher accuracy.

According to the invention, the additional use of the longitudinal acceleration sensor 7 and/or the plausibility check of the driving force F or the driving power PA in each case on the basis of the drive slip S makes the accuracy of the mass determination according to Newton's second law (first embodiment) or the power set (second embodiment) qualitative clearly improved. For this purpose, the procedure according to the flow chart in 3 for example as follows:

• - eine Korrektur des ersten Beschleunigungs-Wertes AW1 und/oder des Geschwindigkeits-Wertes VW in Abhängigkeit eines oder mit einem Korrektur-Faktor K anhand der Plausibilisierung mit dem zeitgleich ermittelten zweiten Beschleunigungs-Wert AW2, und/oder
• - eine Korrektur des Antriebskraft-Wertes FW mit dem Kraft-Korrektur-Wert FKW in Abhängigkeit der zeitgleich wirkenden Hangabtriebskraft FH, und/oder
• - eine Plausibilisierung des Antriebskraft-Wertes FW und/oder des Antriebsleistungs-Wertes PAW über den zeitgleich wirkenden Antriebschlupf S mit entsprechender Ermittlung des jeweiligen Qualitäts-Faktors Q1, Q2 erfolgt.

After the initialization, in a first step ST1, the drive force values FW and/or the drive power values PAW are determined and/or read for a specific point in time t as a function of the engine torque D and other influencing factors, such as losses AV in the drive train 55. In a second step ST2, the first acceleration values AW1 and/or the speed values VW are also determined and/or read for the same point in time t, each depending on the respective wheel speeds N of the wheels 5 of the vehicle. In a third step ST3, individual mass values MWi are obtained from the driving force value FW and the second acceleration value AW1 and/or determined from the drive power value PAW and the speed value VW for the respective point in time t

• - a correction of the first acceleration value AW1 and/or the speed value VW as a function of or with a correction factor K based on the plausibility check with the second acceleration value AW2 determined at the same time, and/or
• - A correction of the drive force value FW with the force correction value FKW depending on the slope force FH acting at the same time, and/or
• - A plausibility check of the drive force value FW and/or the drive power value PAW is carried out via the drive slip S acting at the same time with a corresponding determination of the respective quality factor Q1, Q2.

These three steps ST1 to ST3 are carried out continuously for a number of points in time t and then, in a fourth step ST4, the estimated mass value MW is calculated from the plurality of determined individual mass values MWi by forming a mean mass value MWM (arithmetic mean) and output as the vehicle mass M , where the individual mass values MWi can be weighted accordingly with the respective quality factor Q1, Q2.

It can also be provided that both embodiments are linked with one another, i.e. a mean mass value MWM or an estimated mass value MW is formed from the individual mass values MWi corrected according to the first embodiment and the individual mass values MWi corrected according to the second embodiment.

Reference List

1

vehicle

1a

towing vehicle

1b

trailer

2

electronic braking system

3

central module

4

mass estimation unit

5

wheels of the vehicle

5V

front wheels

5H

rear wheels

6

wheel speed sensors

7

longitudinal acceleration sensor

10

roadway

50

drive

51

drive control

55

powertrain

A

vehicle acceleration

A5

wheel acceleration

AV

Powertrain losses 55

AW1

first acceleration value

AW2

second acceleration value

b

number of pairs of values

D

engine torque

dAW

Deviation between AW1 and AW2

German

temporal change

Ekin

kinetic energy

HE

rotation proportion

ET

translation part

f

driving force

FH

downhill force

HFC

Force Correction Value

FL

air resistance

FR

rolling resistance

FSt

incline resistance

FV

total driving resistance

fw

Upload Value

GAW

Deviation Limit

i

index

J

moment of inertia

K

correction factor

L

longitudinal direction

M

vehicle mass

MW

mass estimate

MWi

mass single value

MWM

mass mean

N

wheel speeds

NH

rear wheel speeds

NV

Front Wheel Speeds

NW

tilt angle

p

Number of individual mass values MWi

PA

drive power

PAW

drive power value

PV

dissipation

Q1

first quality factor

Q2

second quality factor

R1

first regression line

R2

second regression line

S

drive slip

SD

Slip Chart

t

time

t1

first time

t2

second point in time

V

vehicle speed

VW

speed value

ω

angular velocity

WA1

first value distance

WA2

second value distance

WP1

first pair of values (S, FW)

WP2

second pair of values (S, PAW)

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 3262386 A1 [0004]
• EP 3262385 A1 [0004]
• WO 2016135317 A1 [0004]
• DE 602004003387 T2 [0004]
• DE 102017129828 A1 [0005]
• EP 3019379 B1 [0005]
• EP 3077781 A1 [0005]
• DE 4228413 A1 [0005]
• EP 3501924 A1 [0005]
• DE 19728769 A1 [0005]
• EP 2502759 B1 [0006]
• EP 1951534 B1 [0007]
• DE 102016200778 A1 [0008]
• DE 102013008839 A1 [0009]

Claims (15)

Method for determining a vehicle mass (M) of a vehicle (1) having a drive (50) for generating an engine torque (D), the vehicle (1) being provided with a driving force (F) and a driving power ( PA) is accelerated in a longitudinal direction (L) with a vehicle acceleration (A), with a drive force value (FW) and/or a drive power value (PAW) being determined as a function of the engine torque (D), with the driving force value (FW) characterizes the driving force (F) and the driving power value (PAW) characterizes the driving power (PA); - A first acceleration value (AW1) is determined as a function of wheel speeds (N) of wheels (5) of the vehicle (1) and/or a speed value (VW); - a mean mass value (MWM) is calculated from a number of individual mass values (MWi), with the mean mass value (MWM) characterizing the vehicle mass (M) and an individual mass value (MWi) - from a determined driving force value (FW ) and a simultaneously determined first acceleration value (AW1), or - follows from a drive power value (PAW) and a simultaneously determined speed value (VW), characterized in that - the first acceleration value (AW1) and/ or the speed value (VW) for calculating the individual mass values (MWi) is corrected with a correction factor (K), the correction factor (K) depending on a deviation (dAW) between the first acceleration value ( AW1) and a second acceleration value (AW2) determined at the same time, with the second acceleration value (AW2) characterizing the vehicle acceleration (A) and being determined independently of the wheel speeds (N), and/or - the drive force value (FW ) is corrected with a force correction value (FKW) to calculate the individual mass values (MWi), the force correction value (FKW) being dependent on a slope force (FH) acting on the vehicle (1) at the same time, and/or - the individual mass values (MWi) are each weighted with a first quality factor (Q1) or a second quality factor (Q2) to calculate the mean mass value (MWM), with the first quality factor (Q1 ) indicates an accuracy of the drive force value (FW), as a function of which the respective individual mass value (MWi) is calculated, and the second quality factor (Q2) indicates an accuracy of the drive power value (PAW), as a function of which the respective Mass Single Value (MWi) is calculated indicates. procedure after claim 1 , characterized in that the second acceleration value (AW2) is determined by a longitudinal acceleration sensor (7) in the vehicle (1) at the same time as the first acceleration value (AW1), the correction factor (K) depending on the deviation ( dAW) between the first acceleration value (AW1) and the second acceleration value (AW2) is defined in such a way that the deviation (dAW) is compensated for when the first acceleration value (AW1) is corrected with the correction factor (K). becomes. procedure after claim 1 or 2 , characterized in that the first acceleration value (AW1) and/or the speed value (VW) is corrected with the correction factor (K) if the deviation (dAW) is above a deviation limit value (GAW) lies. procedure after claim 2 or 3 characterized in that the correction factor (K) and/or the deviation (dAW) for determining the correction factor (K) is determined when an angle of inclination (NW) of a roadway (10) on which the vehicle (1st ) moves is zero. procedure after claim 4 , characterized in that the angle of inclination (NW) is determined as a function of the second acceleration value (AW2) of the longitudinal acceleration sensor (7). procedure after claim 4 or 5 , characterized in that the slope force (FH) is determined from the second acceleration value (AW2) and/or from the angle of inclination (NW). Method according to one of the preceding claims, characterized in that the driving force value (FW) and/or the driving power value (PAW) is determined as a function of losses (AV) in a drive train (55) of the vehicle (1). Method according to one of the preceding claims, characterized in that the individual mass values (MWi) are determined for the respective point in time (t). - MWi = FW/(AW1 × K), if the first acceleration value (AW1) is corrected with the correction factor (K), and/or - MWi = (FW - FKW)/(AW1), if the driving force value (FW) is corrected with a force correction value (FKW). Method according to one of the preceding claims, characterized in that the individual mass values (MWi) are determined from speed values (VW) at two different points in time (t) and drive power values (PAW) for these two points in time (t), the two points in time (t) being selected in such a way that a total driving resistance (FV) assigned to the points in time (t) does not change significantly between the two points in time (t). procedure after claim 9 , characterized in that the speed values (VW) for the two different points in time (t) are corrected as a function of the correction factor (K). Method according to one of the preceding claims, characterized in that the individual mass values (MWi) which follow from the driving force value (FW) are multiplied by the respective first quality factor (Q1), and the individual mass values (MWi ), which follow from the drive power value (PAW), are multiplied by the respective second quality factor (Q2). Method according to one of the preceding claims, characterized in that continuously - first pairs of values (WP1) from a drive slip (S) between front wheels (5V) and rear wheels (5H) of the vehicle (1) and a driving force value (FW) present at the same time and /or - second pairs of values (WP2) are formed from the drive slip (S) between the front wheels (5V) and the rear wheels (5H) of the vehicle (1) and a drive power value (PAW) present at the same time, with - from the first pairs of values (WP1) a first regression line (R1) and/or a second regression line (R2) is determined from the second pairs of values (WP2) and - for each first pair of values (WP1) a first value distance (WA1) between the first pair of values (WP1 ) and the first regression line (R1) and/or - for every second pair of values (WP2) a second value distance (WA2) between the second pair of values (WP2) and the second regression line (R2) is determined, with - the first pair of values ( WP1) a first quality factor (Q1) depending on its first value difference (WA1) and/or - the second value pair (WP2) is assigned a second quality factor (Q2) depending on its second value difference (WA2). , and the respective individual mass value (MWi), - which follows from the driving force value (FW) of the respective first pair of values (WP1), is weighted with the first quality factor (Q1) assigned to this first pair of values (WP1), and /or - which follows from the drive power value (PAW) of the respective second pair of values (WP2), is weighted with the second quality factor (Q2) assigned to this second pair of values (WP2). procedure after claim 12 , characterized in that the drive slip (S) is adjusted to zero in a freely rolling manner. Mass estimation unit (4) for carrying out a method according to any one of the preceding claims. Vehicle (1) with a mass estimation unit (4). Claim 14 for carrying out a method according to one of Claims 1 until 13 .

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