Method and device for determining a vibration-relevant parameter of a vehicle output shaft

Abstract

A method for determining the parameter value of a vibration-relevant parameter of an output shaft of a motor vehicle's drive system is described, wherein the output shaft is driven by a drive motor and is configured to drive a wheel of the motor vehicle. The method includes abruptly changing the motor torque produced by the drive motor and determining the time-dependent rotational speed profile of a component of the drive system caused by the change in motor torque. Furthermore, the method includes determining the parameter value of the vibration-relevant parameter of the output shaft based on the time-dependent rotational speed profile.

Description

[0001] The invention relates to a method and a corresponding device designed to efficiently and precisely determine one or more parameters of the output shaft of a vehicle that describe the vibration behavior of the output shaft.

[0002] A (motorized) vehicle comprises a drive system with a drive motor configured to drive one or more output shafts of the drive system, each of which is connected to a wheel of the vehicle. During operation, one or more control systems may be used to ensure stable vehicle operation. For example, slip control of the vehicle's one or more wheels may be implemented. Alternatively or additionally, one or more model-based observers may be used to determine estimated values ​​for one or more measured variables (such as the force acting on the tire of a wheel).

[0003] For the operation of the vehicle, in particular for the operation of a control system and / or an observer, a mathematical and / or computational model of the vehicle can be used, wherein the vehicle model comprises parameter values ​​for a multitude of different model parameters. The vehicle model can, in particular, include one or more model parameters that describe the vibration behavior of the one or more output shafts of the vehicle's drive system.

[0004] This document addresses the technical task of efficiently and reliably determining parameter values ​​for one or more vibration-relevant parameters of an output shaft of the drive system of a (motor) vehicle.

[0005] The problem is solved by each of the independent claims. Advantageous embodiments are described, inter alia, in the dependent claims. It should be noted that additional features of a claim dependent on an independent claim, without the features of the independent claim itself or only in combination with a subset of the features of the independent claim, can constitute a separate invention independent of the combination of all features of the independent claim, which can be made the subject of an independent claim, a divisional application, or a subsequent application. This applies equally to technical teachings described in the description, which can constitute an invention independent of the features of the independent claims.

[0006] According to one aspect, a method for determining the parameter value of (at least) one vibration-relevant parameter of an output shaft of a motor vehicle's drive system is described. The output shaft can be modeled as a torsion bar. The vibration-relevant parameter of the output shaft can relate to a torsional vibration of the output shaft. For example, the vibration-relevant parameter of the output shaft can be the spring constant of a torsion spring that describes the torsional vibration of the output shaft. Alternatively or additionally, the vibration-relevant parameter of the output shaft can be the damping of a torsional damper that describes the torsional vibration of the output shaft.

[0007] The output shaft is driven by an (electric) drive motor of the drive system. Furthermore, the output shaft is designed to drive a wheel of the vehicle. The motor shaft of the drive motor can be mechanically coupled to the output shaft via one or more gearboxes. The one or more gearboxes can provide a specific gear ratio. G exhibit.

[0008] The method involves abruptly changing (in particular increasing) the motor torque produced by the drive motor (e.g., by 10% or more, or by 20% or more). The motor torque can be increased, in particular. This abrupt change causes vibrations in the drive system, especially vibration of the output shaft.

[0009] The method further includes determining the temporal profile of the rotational speed of a component of the drive system caused by changes in engine torque. The component of the drive system for which the temporal profile of the rotational speed is determined can be, in particular, the drive motor, especially its shaft. Alternatively or additionally, the component of the drive system for which the temporal profile of the rotational speed is determined can be the wheel coupled to the output shaft. The rotational speed of the drive motor, especially its shaft, and / or the wheel speed can be recorded efficiently and precisely (using sensors already installed in the vehicle).

[0010] Furthermore, the method includes determining the parameter value of the vibration-relevant parameter of the output shaft based on the temporal profile of the rotational speed, in particular based on the oscillation of the rotational speed over time. The oscillation of the rotational speed over time can be described by one or more parameters, in particular by the oscillation frequency and / or by the damping of the oscillation. The parameter value of the vibration-relevant parameter of the output shaft can be determined in a particularly precise manner based on one or more parameters of the oscillation of the rotational speed over time.

[0011] Within the framework of this method, the mean change in rotational speed (in particular, the mean rate of change in rotational speed) caused by a change in motor torque can be determined based on the rotational speed over time. A compensated rotational speed profile can be determined based on the rotational speed profile over time and the mean change in rotational speed. The compensated rotational speed profile preferably exhibits an oscillation around a constant, stable mean value. The parameter value of the vibration-relevant parameter of the output shaft can be determined with particular precision based on the compensated rotational speed profile over time, specifically based on one or more parameters of the oscillation of the compensated rotational speed profile.

[0012] A function, in particular a control system and / or an observer, of the motor vehicle (especially the vehicle's drive system) can be operated depending on the determined parameter value of the vibration-relevant parameter of the output shaft. The determined parameter value can be used in a computational model that is used for the operation of the motor vehicle's function. This allows for particularly comfortable, robust, and safe operation of the motor vehicle's function.

[0013] Within the framework of the procedure, the vibration frequency f eThe oscillation of the (compensated) time-dependent rotational speed can be determined. For this purpose, the cumulative duration of N periods of the oscillation of the (compensated) time-dependent rotational speed, with N>1, can be determined. The cumulative duration can be determined as the time between two (successive) wave crests and / or two (successive) wave troughs of the oscillation of the time-dependent rotational speed. The oscillation frequency f e can be determined with particular precision based on the cumulative time duration. The parameter value of the vibration-relevant parameter of the output shaft can be determined based on the vibration frequency f. e to be determined.

[0014] As previously explained, the vibration-relevant parameter of the output shaft can be the spring constant of the torsional spring that describes the torsional vibration of the output shaft. The parameter value of the spring constant can be determined using the following formula. kc=pJm(πiGfe)2 In this context, J describes, in particular, m the inertia of the drive motor (which results, for example, from the drive motor's specifications). i G This describes, in particular, the gear ratio between the drive motor and the output shaft and / or the wheel. By using the aforementioned formula, the parameter value of a vibration-relevant parameter, especially the spring constant, of the output shaft can be determined with particular precision.

[0015] In the formula above, p is a proportionality factor that depends, in particular, on the number of output shafts of the drive system driven by the drive motor. The drive system can be configured such that the drive motor drives two output shafts, e.g., a right output shaft for a right wheel and a left output shaft for a left wheel. Alternatively, the drive system can be configured such that the drive motor drives exactly one output shaft. If necessary, the drive system can have a dedicated drive motor for each output shaft (e.g., for the right output shaft and for the left output shaft). The proportionality factor can be p = 2 if the drive motor drives (exactly) two output shafts. Conversely, the proportionality factor can be p = 4 if the drive motor drives (exactly) one output shaft.

[0016] Within the framework of the procedure, the damping coefficient d can be determined. e The damping coefficient d can be determined for the oscillation of the (compensated) time-dependent rotational speed. For this purpose, the time sequence of the absolute value of the amplitude of the wave crests and / or the wave troughs of the oscillation of the (compensated) time-dependent rotational speed can be determined. e The vibration-relevant parameter of the output shaft can be determined with particular precision based on the temporal sequence of the absolute value of the amplitude of the wave crests and / or troughs. Furthermore, the parameter value of the vibration-relevant parameter of the output shaft can be determined based on the damping coefficient d. e to be determined.

[0017] As already explained, the vibration-relevant parameter of the output shaft can affect the damping d cof the torsional damper that describes the torsional vibration of the output shaft. The damping parameter value can be precisely determined using the following formula: dc=pJmπiG2fede

[0018] It should be noted that, particularly when using an internal combustion engine, the gear ratio i G This varies for different gears of the transmission. Within the scope of the procedure, different gear ratios can be determined for different gears of the drive system (and thus for different values ​​of the gear ratio i). G Parameter values ​​are determined for one or more vibration-relevant parameters of the output shaft of the drive system. These can then be used in a gear-dependent manner during the operation of a vehicle function. This allows the performance of the vehicle function to be further improved.

[0019] According to another aspect, a device for determining a parameter value of a vibration-relevant parameter of an output shaft of the drive system of a motor vehicle is described. The output shaft is driven by an (electric) drive motor. Furthermore, the output shaft is designed to drive a wheel of the motor vehicle.

[0020] The device is designed to cause the drive motor to produce a sudden change in motor torque. For example, a sudden change of 10% or more, or 20% or more in the value of the motor torque can be produced.

[0021] The device is further configured to determine the temporal profile of the rotational speed of a component of the drive system (in particular the drive motor and / or the wheel) caused by changes in the motor torque. The parameter value of the vibration-relevant parameter of the output shaft can then be determined based on the temporal profile of the rotational speed.

[0022] According to another aspect, a (road) motor vehicle (in particular a passenger car or a truck or a bus or a motorcycle) is described that includes the device described in this document.

[0023] It should be noted that the aspects described in connection with the method, in particular the claims described in connection with the method, are also to be applied to the device as corresponding device features.

[0024] Another aspect described is a software (SW) program. The SW program can be configured to run on a processor (e.g., on a vehicle's control unit) and thereby execute the procedure described in this document.

[0025] Another aspect describes a storage medium. This storage medium can include a software program configured to run on a processor and thereby execute the procedure described in this document.

[0026] It should be noted that the methods, devices, and systems described in this document can be used both alone and in combination with other methods, devices, and systems described in this document. Furthermore, any aspect of the methods, devices, and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways. Features listed in parentheses are to be understood as optional features.

[0027] The invention will now be described in more detail using exemplary embodiments. Fig. 1a Exemplary components of a vehicle; Fig. 1b an exemplary propulsion system of a vehicle; Fig. 1c an exemplary computational model for a vehicle; Fig. 2. An exemplary time course of the rotational speed of a component of the drive system in response to a change in motor torque; and Fig. 3 a flowchart of an exemplary procedure for determining a vibration-relevant parameter of an output shaft of the drive system of a vehicle.

[0028] As stated at the outset, this document deals with the efficient and precise determination of the parameter value of one or more vibration-relevant parameters of an output shaft of the drive system of a (motor) vehicle. In this context, it shows Fig. 1a Exemplary components of a vehicle 100. The vehicle 100 comprises a (particularly electric) drive motor 103 for driving the vehicle 100. The drive motor 103 is part of the drive system of the vehicle 100. The drive motor 103 is designed to drive one or more wheels 105 of the vehicle 100.

[0029] The vehicle 100 may include a speed sensor 102 configured to acquire sensor data relating to the rotational speed of a component of the vehicle 100's drive system, in particular the rotational speed of a wheel 105 of the vehicle 100 and / or the rotational speed of the vehicle 103's drive motor. An evaluation device 101 of the vehicle 100 may be configured to evaluate the sensor data from the speed sensor 102, for example, to determine the parameter values ​​of one or more vibration-related parameters of an output shaft of the vehicle 100's drive system.

[0030] Fig. Figure 1b shows an exemplary drive system 110 of the vehicle 100. The (electric) drive motor 103 can be operated with electrical energy from an electrical energy storage device 111 of the vehicle 100. The phase voltages and / or phase currents for the operation of the drive motor 103 can be generated from the direct current supplied by the energy storage device 111 using an inverter 112.

[0031] The drive motor 103 has a motor shaft 113. The drive motor 103 is configured to produce a specific rotational speed ωm of the motor shaft 113. Furthermore, the drive motor 103 is configured to produce a specific torque (i.e., motor torque) T. m to effect on motor shaft 113.

[0032] The motor shaft 113 is mechanically connected via a gearbox 114 (with the gear ratio i) T ) and / or via a differential 115 (with the gear ratio i) D) coupled to the one or more output shafts 116 of the drive system 110, wherein each output shaft 116 is mechanically (rigidly) coupled to a wheel 105 of the vehicle 100. The transmission 115 and the differential 115 provide an overall gear ratio i G = i T i D When using a differential 115, the motor shaft 113 is typically coupled to several (especially two) drive shafts 116.

[0033] An output shaft 116 (driven by the motor shaft 113) and / or the corresponding wheel 105 have a rotational speed ω ω and a torque T ω up. The in Fig. The indices “r” and “1” shown in 1b refer to the right and left wheel 105 and the right and left output shaft 116, respectively. The rotational speed ω ωThe mean speed of the left and right output shafts 116 can be used. Furthermore, it can be assumed that the torque at the right wheel 105 and at the left wheel 105 is the same.

[0034] An output shaft 116 can be modeled as a torsion bar, in particular as a combination of a torsion spring and a torsion damper, with a spring constant k, with respect to the vibration behavior of the output shaft 116. c (the torsion spring) and with a damping d c (of the torsional damper).

[0035] The drive system 100 can be considered a transmission system with a transfer function. The input vector of the transmission system can be u = [T]. m ω ω ] T can be used. The torque T can be used as the output variable of the transmission system. ωThe transmission system can be considered at an output shaft 116 and / or at a wheel 105 of the drive system 100. It can be shown that the transmission system is a second-order linear system. The transfer function can be determined as follows: G(s)=dc / (JmiG)s+kc / (JmiG)s2+(2dc) / (JmiG2)s+(2kc) / (JmiG2)=(a1s+a2)s2+2deωes+ωe2.

[0036] The transfer function can therefore be determined using a generic PDT2 filter with the angular frequency ω. e = 2πf e and the damping coefficient d e can be described. A comparison of coefficients yields... 2dcJmiG2=2deωe 2kcJmiG2=ωe2

[0037] Based on this, the spring constant k can be determined. c and the damping factor d c be determined as kc=2Jm(πiGfe)2 dc=2JmπiG2fede

[0038] The parameter values ​​of the two parameters k c , d cThe output shaft 116 can thus be determined, based on • the inertia of the engine J m , • the gear ratio i G , • the oscillation frequency f e , and • the damping coefficient d e .

[0039] The inertia of the engine and the gear ratio are typically known values ​​that can be determined, for example, from CAD data of the vehicle 100.

[0040] The oscillation frequency f e and the damping coefficient d e can be determined based on a step response of the transmission system. For this purpose, the transmission system (i.e., the drive system 110) can be subjected to a step change, in particular an increase, in the motor torque T produced by the drive motor 103. mFurthermore, the speed profile of a component of the drive system 110 in response to the abrupt change in engine torque T can be determined using the speed sensor 102 of the vehicle 100. m can be recorded. In particular, the time course of the motor speed (of the drive motor 103) and / or the time course of the wheel speed (of the wheel 105) can be recorded.

[0041] In Fig. Figure 2 shows, as an example, the (compensated) time course 201 of the rotational speed of the drive motor 103. In this case, Fig. 2. The longitudinal acceleration of the rotational speed is compensated (so that the compensated time profile 201 oscillates around a constant rotational speed value). The time profile 201 of the rotational speed of the drive motor 103 can be efficiently recorded (e.g., based on the position sensor of the rotor of the electric drive motor 103).

[0042] As from Fig. As can be seen in Figure 2, the (compensated, in particular the illumination-compensated) time course 201 of the rotational speed exhibits an oscillation with the oscillation frequency f e to determine the oscillation frequency f e can the cumulative period τ e 203 of N oscillation periods, with N≥1, can be determined, and the oscillation frequency f can be calculated based on this. e be determined as fe=1τe∗1N

[0043] The individual periods are bounded, for example, by two directly consecutive wave crests 202 or by two directly consecutive wave troughs 204. Alternatively or additionally, the zero crossings or another reference point of the time course 201 can be used to identify the individual periods.

[0044] The oscillation of the (compensated) time course 201 of the rotational speed exhibits damping. The damping coefficient d eThe damping can be determined, for example, based on the time course of the absolute value of the successive wave crests 202 and / or wave troughs 204 of the time course 201 of the rotational speed. For this purpose, the method described in J. Darling, D. Tilley, and B. Gao, “An experimental investigation of car-trailer high speed stability,” Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, vol. 223, no. 4, pages 471–484, 2009, can be used. The cited publication is hereby incorporated in its entirety into this document by reference.

[0045] Based on the temporal profile of the rotational speed of a component of the drive system of a vehicle, parameter values ​​for one or more vibration-relevant parameters can be determined. c , d cThe parameters of an output shaft 116 of the vehicle 100 can be determined. These parameter values ​​can be used during the operation of the vehicle 100, e.g., within a control system and / or within an observer.

[0046] The parameter values ​​of one or more vibration-relevant parameters k c , d c An output shaft 116 of the drive system 110 can be used in particular in a computational model 120, as exemplified in Fig. 1c is shown. The calculation model 120 can determine the parameter values ​​122 of one or more parameters k. c , d c record the parameter values ​​122 of one or more parameters k c , d c The output shaft 116 may have been determined in advance of the operation of the vehicle 100.

[0047] Furthermore, measured values ​​121 of one or more measured variables of the vehicle 100 can be recorded (during the operation of the vehicle 100). The measured values ​​121 can be acquired during the operation of the vehicle 100. The computational model 120 can be configured to determine at least one output value 123 based on the measured values ​​121 of the one or more measured variables, which can be used for the operation of the vehicle 100, e.g., within the framework of a control system and / or an observer of the vehicle 100.

[0048] In a vehicle dynamics control system 100, a model-based controller and / or a model-based observer can be used, each employing a computational model 120 based on a multitude of vehicle parameters (i.e., parameter values ​​122 of vehicle parameters). The parameters can include the equivalent spring constant k. c and / or the replacement damping d cinclude, which represent the one or more output shafts 116 of the vehicle 100 as torsion bars.

[0049] An example of a controller is a (multi-)slip controller, which can be part of the traction control and / or the anti-lock braking system of the vehicle 100. The slip controller can be configured to prevent wheel spin or locking of one or more wheels 105 of the vehicle and / or to maintain the steerability of the vehicle 100 during critical driving maneuvers. Furthermore, the longitudinal acceleration of the vehicle 100 can be optimized, thereby improving, for example, the braking distance and acceleration time of the vehicle 100. The concept of input-output linearization can be used for the slip controller, which employs a longitudinal model (i.e., a computational model 120) of the vehicle 100 including the powertrain (i.e., drive system 110). An exemplary slip controller is described in DE102020112597A1. The cited publication is hereby incorporated in its entirety into the present document by reference.

[0050] An example of an observer is the tire force observer, which estimates the forces on the tire of a wheel 105 in the longitudinal direction. These observed tire forces can be used for the operation of one or more functions of the vehicle 100. A PI observer or a linear Kalman filter can be used for the tire force observer. A longitudinal model (i.e., a computational model 120) including the powertrain (i.e., drive system) 110 of the vehicle 100 is used. An exemplary slip controller is described in DE102022125522A1. The cited publication is hereby incorporated in its entirety into this document by reference.

[0051] A vehicle model can describe actuators, the drivetrain 110, tires, and / or the longitudinal dynamics of the vehicle 100. The drivetrain (i.e., the drive system 110) describes the transmission behavior from the drive motor 103 to the one or more wheels 105 of the vehicle 100 and includes the differential 115 and / or the transmission 114 (depending on the number of drive motors 103) as well as the one or more output shafts 116 of the vehicle 100. The one or more (relatively) flexible output shafts 116 are typically largely responsible for drivetrain vibrations and can each be described as a torsion bar consisting of an equivalent spring constant k. c and / or a replacement damping d cThese parameters can be modeled. Incorrect parameter values ​​for the equivalent spring constant and / or the equivalent damping can impair the quality of the control system or the quality of the observed quantity. This can lead to a perceptible impairment of one or more vehicle characteristics (e.g., during ABS braking and / or acceleration).

[0052] This document describes a method for precisely determining the parameter value of the equivalent spring constant and / or the equivalent damping using the motor and / or wheel speed. The (electric) drive motor 103 can be excited abruptly, and the resulting vibrations at the motor or wheel speed can be analyzed. The equivalent spring constant and / or the equivalent damping can each be determined using an equivalent formula.

[0053] The method described in this document can be used for a drive system 110 in which the drive axle is driven by two (electric) drive motors 103. Each of the two drive motors 103 can drive one wheel 105 (of the drive axle) (each via a gearbox 114 and / or each via an output shaft 116). The open differential 115 can then typically be omitted. The following formulas can be used to determine the parameter values ​​of the one or more vibration-relevant parameters of the respective output shaft 116. kc=4Jm(πiGfe)2 dc=4JmπiG2fede

[0054] The procedure described in this document can be applied to a drive system 110 with an internal combustion engine as the drive motor 103. The parameter values ​​of the equivalent spring constant k c and / or the replacement damping d ccan then be calculated depending on the gear. In particular, the gear ratio i can be calculated for each gear of transmission 114. G to be determined. This translation ratio i G This can then be used in the above formulas to determine values ​​for the equivalent spring constant k. c and / or the replacement damping d c to determine the values ​​for the equivalent spring constant k. c and / or the replacement damping d c They can be determined in a particularly precise manner (e.g. by averaging) such that the values ​​adjusted for the respective translation ratio are equal.

[0055] The procedure described in this document can be applied to a drive axle with a controlled locking differential 115. In other words, the differential 115 of the drive system 110 can be a locking differential. Values ​​for the equivalent spring constant k c and / or the replacement damping d ccan be determined using the above formulas.

[0056] The formulas for determining parameter values ​​for the equivalent spring constant k c and / or the replacement damping d c can be written generally as kc=4mJm(πiGfe)2 dc=4mJmπiG2fede where m is the number of output shafts 116 driven by a drive motor 103 of the drive system 110. The term 4m can be used as a proportionality factor p=4m be defined.

[0057] Fig.Figure 3 shows a flowchart of an exemplary (possibly computer-implemented) method 300 for determining a parameter value of a vibration-relevant parameter 122 of an output shaft 116 of the drive system 110 of a motor vehicle 100. The method 300 can be executed by the control device 101 of the motor vehicle 100. Alternatively, the method 300 can be executed by a computing unit located outside the vehicle 100.

[0058] The output shaft 116 is driven by a (possibly electric or internal combustion engine) drive motor 103. Furthermore, the output shaft 116 is designed to drive a wheel 105 of the motor vehicle 100. For this purpose, the wheel 105 can be rigidly coupled to the output shaft 116, in particular such that the torque T ω The output shaft 116 and the wheel 105 are the same. On the other hand, the rotational speed ω ωThe speeds of the output shaft 116 (at the output of the gearbox 114 and / or the differential 115) and the wheel 105 are not the same due to the twisting of the output shaft 116. The speed of the output shaft 116 at the output of the gearbox 114 and / or the differential 115 can be approximated based on the engine speed (taking the gear ratio into account). The speed of the output shaft 116 at the wheel 105 can be approximated by the wheel speed.

[0059] Method 300 comprises the abrupt change 301 (in particular, increasing) of the motor torque T produced by the drive motor 103. m Furthermore, the procedure 300 includes determining 302 the change in engine torque T. m caused time course of the rotational speed ω m , ω ω a component 103, 105 of the drive system 110. The time course of the rotational speed ω is preferably used. m , ω ωof the drive motor 103 and / or the wheel 105, which can be efficiently detected by (typically already installed) sensors 102.

[0060] Method 300 further includes determining 303 the parameter value of the vibration-relevant parameter 122 of the output shaft 116 based on the time course of the rotational speed ω. m , ω ω The time course of the rotational speed ω m , ω ω typically exhibits an oscillation, where the oscillation has one or more oscillation parameters, such as the oscillation frequency f. e the vibration and / or the damping coefficient d e of the vibration. The parameter value of the vibration-relevant parameter 122 of the output shaft 116 can be determined in a particularly precise manner based on one or more vibration parameters of the vibration of the time course of the rotational speed ω. m , ω ω to be determined.

[0061] The determined parameter value of the vibration-relevant parameter 122 of the output shaft 116 can be used for the operation of one or more functions of the motor vehicle 100. This allows for particularly comfortable and safe operation of the one or more vehicle functions.

[0062] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and the figures are intended only to illustrate the principle of the proposed methods, devices, and systems by way of example. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102020112597A1

[0049] DE 102022125522A1

[0050] Cited non-patent literature

[0000] Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, vol. 223, no. 4, pages 471-484, 2009

[0044]

Claims

[1] Method (300) for determining a parameter value of a vibration-relevant parameter (122) of an output shaft (116) of a drive system (110) of a motor vehicle (100); wherein the output shaft (116) is driven by a drive motor (103); wherein the output shaft (116) is configured to drive a wheel (105) of the motor vehicle (100); wherein the method (300) comprises, - abrupt change (301) of a motor torque (T) caused by the drive motor (103) m ); - Determine (302) a by changing the engine torque (T m ) caused time course of a rotational speed (ω) m , ω ω ) a component (103, 105) of the drive system (110); and - Determining (303) the parameter value of the vibration-relevant parameter (122) of the output shaft (116) based on the time course of the rotational speed (ω) m , ω ω ). [2] Method (300) according to claim 1, wherein the method (300) comprises, - Determining an oscillation frequency (f e ) an oscillation of the time course of the rotational speed (ω) m , ω ω ); and - Determining the parameter value of the vibration-relevant parameter (122) of the output shaft (116) based on the vibration frequency (f e ). [3] Method (300) according to claim 2, wherein the method (300) comprises, - Determine, based on the time course of the rotational speed (ω) m , ω ω ), one caused by the change in engine torque (T m ) caused mean change in rotational speed (ω m , ω ω ); - Determining a compensated time course (201) of the rotational speed (ω) m , ω ω ) based on the time course of the rotational speed (ω) m , ω ω ) and based on the mean change in rotational speed (ω m , ω ω); and - Determining the oscillation frequency (f e ) based on the compensated time course (201) of the rotational speed (ω m , ω ω ). [4] Method (300) according to any one of claims 2 to 3, wherein the method (300) comprises, - Determining a cumulative time duration (203) of N periods of the oscillation of the time course of the rotational speed (ω) m , ω ω ), with N>1; wherein the cumulative time period (203) is in particular defined as the time period between two wave crests (202) and / or two wave troughs (204) of the oscillation of the time course of the rotational speed (ω) m , ω ω ) is determined; and - Determining the oscillation frequency (f e ) based on the cumulative time duration (203). [5] Method (300) according to any one of claims 2 to 4, wherein - the vibration-relevant parameter (122) of the output shaft (116) a spring constant (k c) a torsional spring describing a torsional vibration of the output shaft (116); - the parameter value of the spring constant (k) c ) is determined based on kc=pJm(πiGfe)2 - p is a proportionality factor which depends in particular on a number of output shafts (116) of the drive system (110) driven by the drive motor (103); - J m describes an inertia of the drive motor (103), in particular is; and - i G a gear ratio between the drive motor (103) and the output shaft (116) and / or the wheel (105). [6] Method (300) according to any one of the preceding claims, wherein the method (300) comprises, - Determining a damping coefficient (d e ) an oscillation of the time course of the rotational speed (ω) m , ω ω ), in particular an oscillation of a with respect to a mean change in rotational speed (ω)m , ω ω ) compensated time course (201) of the rotational speed (ω m , ω ω ); and - Determining the parameter value of the vibration-relevant parameter (122) of the output shaft (116) based on the damping coefficient (d) e ). [7] Method (300) according to claim 6, wherein the method (300) comprises, - Determining a temporal sequence of the absolute value of the amplitude of wave crests (202) and / or wave troughs (204) of the oscillation of the temporal course of the rotational speed (ω) m , ω ω ); and - Determining the damping coefficient (d e ) based on the temporal sequence of the absolute value of the amplitude of the wave crests (202) and / or the wave troughs (204). [8] Method (300) according to one of claims 6 to 7, wherein - the vibration-relevant parameter (122) of the output shaft (116) a damping (d c) a torsional damper describing a torsional vibration of the output shaft (116); - the damping parameter value (d c ) is determined based on dc=pJmπiG2fede - p is a proportionality factor which depends in particular on a number of output shafts (116) of the drive system (110) driven by the drive motor (103); - J m describes an inertia of the drive motor (103), in particular is; - i G a gear ratio between the drive motor (103) and the output shaft (116) and / or the wheel (105); and - f e a vibration frequency of the oscillation of the time course of the rotational speed (ω) m , ω ω ) is. [9] Method (300) according to one of the preceding claims, wherein the component of the drive system (110), for which the time course of the rotational speed (ω) m , ω ω) is determined, includes - the drive motor (103), in particular the shaft (113) of the drive motor (103); and / or - the wheel (105) coupled to the output shaft (116). [10] Method (300) according to one of the preceding claims, wherein the method (300) comprises operating a function, in particular a control system and / or an observer, of the motor vehicle (100) depending on the determined parameter value of the vibration-relevant parameter (122) of the output shaft (116). [11] Device (101) for determining a parameter value of a vibration-relevant parameter (122) of an output shaft (116) of a drive system (110) of a motor vehicle (100); wherein the output shaft (116) is driven by a drive motor (103); wherein the output shaft (116) is configured to drive a wheel (105) of the motor vehicle (100); wherein the device (101) is configured - to cause the drive motor (103) to make a sudden change in motor torque (T m ) to effect; - one through the change in engine torque (T m ) caused time course of a rotational speed (ω) m , ω ω ) of a component (103, 105) of the drive system (110); and - the parameter value of the vibration-relevant parameter (122) of the output shaft (116) based on the time course of the rotational speed (ω) m , ω ω to determine.

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