DE102006017406A1 - Motor vehicle`s superposition steering system operating method, involves limiting gradient of transmission ratio between steering wheel angle and wheel steering angle after detecting condition of vehicle cornering with constant curve radius - Google Patents

Abstract

The method involves providing a steering wheel angle as a measure for a desired wheel steering angle by a steering handle (2). An auxiliary angle is superimposed to the steering wheel angle for realizing a variable transmission ratio between the steering wheel angle and the wheel steering angle to determine an input angle of a steering gear (4). The gradient of the ratio between the angles is limited after detecting the condition of cornering of a motor vehicle with a constant curve radius. Independent claims are also included for the following: (1) a computer program with program code units for execution of a method of operating a steering system (2) a computer program product with program code units for execution of a method of operating the steering system (3) a superposition steering system of a motor vehicle.

Description

The The invention relates to a method for operating a steering system of a Motor vehicle according to the preamble of claim 1. The invention also relates to a computer program and a computer program product with program code means to to carry out such method. Furthermore, the invention relates to a superposition steering system of a Motor vehicle.

State of the art

A superposition steering system with overlay means is for example from DE 40 31 316 A1 known. With the help of the superimposition means, it is possible to superimpose a steering wheel angle predefined by the steering handle for increasing driving stability and / or comfort with an additional angle, so that a variable transmission ratio between steering wheel angle and pinion angle adjusts depending on the driving dynamics and / or comfort. This makes it possible from a safety point of view, a motor vehicle, which threatens to break out, due to a corresponding correction of the steering angle back into a stable driving situation. The superimposing means may assist driving dynamics means of the motor vehicle (for example, an electronic stability program (EPS), an anti-lock braking system (ABS), traction control (ASR), etc.). This is, for example, a yaw rate control in which the steering system corrects the driving dynamics of the motor vehicle in order to regulate the yaw rate to a predefinable value and thereby prevent the vehicle from breaking out. Conveniently, it is possible by the variably selectable gear ratio, for example, at low vehicle speeds (for example, when maneuvering the vehicle) to set a relatively small gear ratio, ie rotation of the steering handle by a certain angle of rotation leads to a relatively large steering angle of the wheels. In contrast, at high vehicle speeds (for example, fast highway driving), a relatively large gear ratio can be adjusted, ie a rotation of the steering handle by a certain angle results in a relatively small steering angle of the wheels, so that the driving stability of the motor vehicle increases. Overall, by overlay steering systems of the type mentioned above with overlay means the handling of a motor vehicle equipped with it can be significantly improved.

The Function of the speed-dependent variable transmission ratio (VSR variable Steering ratio) determined for superposition steering systems dependent on the vehicle longitudinal speed a speed-dependent variable steering ratio between steering wheel angle and wheel steering angle or pinion angle. Out This relationship results in an overlay angle or additional angle, that of the auxiliary angle adjuster of the superposition steering system is set.

is a vehicle with such a superposition steering system, which a speed-dependent realized variable steering ratio, when cornering, in the case of an acceleration or delaying the Problematic of a changing Steering ratio. Therefore, the driver is forced to the wheel steering angle not only due a changing one Curve radius, but also due to the ratio change. For example, if the vehicle accelerates in a curve with a constant radius, does this to an indirect steering ratio. Consequently, the wheel steering angle is reduced when the steering wheel is held. In order to maintain the required wheel steering angle, must the driver increase the steering wheel angle accordingly. Delays the vehicle in the same Situation, the driver is forced to reduce the steering wheel angle, to the desired Maintain curve radius.

Furthermore, the concerns DE 10 2004 009 815 A1 a steering system of a motor vehicle with a steering handle for specifying a steering wheel angle as a measure of a desired steering angle for at least one steerable wheel of the motor vehicle. The steering system also includes overlay means for generating an additional angle and for superimposing the steering wheel angle with the additional angle. A pinion angle results from the sum of the steering wheel angle and the additional angle. Finally, the steering system comprises a steering gear for converting the pinion angle into a corrected steering angle for the at least one steerable wheel of the motor vehicle. In order to further improve the manageability of motor vehicles equipped with such steering systems, it is proposed that the superimposition means generate the additional angle as a function of a driving situation of the motor vehicle, except for the driving speed of the motor vehicle. The above-described problem of an acceleration or deceleration process during cornering with a constant radius is not addressed.

Disclosure of the invention

Technical task

Based on this, the present invention has the object to provide a method for operating a steering system of a motor vehicle, a computer program, a computer program product and a superposition steering system of a motor vehicle of the type mentioned, wel Avoid the disadvantages of the prior art, especially at an approximately constant steering wheel angle when cornering a wheel steering angle change due to a Lenkübersetzungsänderung prevent or limit.

Technical solution

These The object is achieved by the solved in claim 1 features.

The Task is relative of the computer program of claim 8, relating to the computer program product by claim 9 and with respect of the superposition steering system solved by claim 10.

Thereby, that after detection of a condition of cornering of the motor vehicle with at least approximate constant radius at least the gradient of the transmission ratio between is limited to the steering wheel angle and the wheel steering angle, it is ensured that at least approximately constant steering wheel angle a Radlenkwinkeländerung due to a steering gear change at least severely limited so this will be for The driver barely noticeable is.

Advantageous it is when, after detecting a first state of the cornering of the motor vehicle with approximately constant curve radius, the gradient of the transmission ratio is limited between the steering wheel angle and the wheel steering angle.

In a particularly advantageous procedural embodiment of the invention can also be provided that after detection of a second Condition of cornering of the motor vehicle with a constant radius of curvature the gear ratio between the steering wheel angle and the wheel steering angle kept at least approximately constant becomes.

Thereby is virtually eliminated in a simple and advantageous manner, that the driver during a constant cornering during a Acceleration or deceleration process as a result of a changing steering ratio correct or redirect to maintain the radius of curvature.

Of the first state can be detected when for a predetermined first period of time the amount of steering wheel angle over a predetermined threshold and the steering wheel angular velocity lies in a given interval.

• – der Betrag des Lenkradwinkels über einem vorgegebenen Schwellwert liegt,
• – die Lenkradwinkelgeschwindigkeit in einem vorgegebenen Intervall liegt,
• – die Querbeschleunigung des Kraftfahrzeugs in einem vorgegebenen Intervall liegt und
• – die Gierrate des Kraftfahrzeugs in einem vorgegebenen Intervall liegt.

Furthermore, the second state can be detected if, for a predetermined second period of time:

• The amount of the steering wheel angle is above a predetermined threshold value,
• The steering wheel angular velocity lies within a predetermined interval,
• - The lateral acceleration of the motor vehicle is within a predetermined interval and
• - The yaw rate of the motor vehicle is within a predetermined interval.

Advantageous it is when after detection of a termination of the state the turning of the motor vehicle with at least approximately constant Curve radius the gear ratio between the steering wheel angle and the wheel steering angle again the current speed of the motor vehicle is adjusted.

at constant steering wheel angle became the speed-dependent constraint condition the steering ratio broken to an at least approximately constant steering ratio to be able to maintain. Remains in the case of a constant steering wheel angle during the Cornering the steering ratio constant, so this must be at a corresponding steering wheel angle change by the driver again to the current speed Steering translation be transferred.

According to the invention may further be provided that the gradient of the gear ratio when re-adapting to the current speed of the motor vehicle dependent on the current steering wheel angle and the current steering wheel angular velocity results.

Becomes after at least approximately Constant cornering the steering ratio back to the current vehicle longitudinal speed adapted - so after a renewed steering intervention by the driver - must be appropriate transition from the currently constant translation created for vehicle speed-dependent translation, to avoid making unadjusted changes from the driver as implausible Vehicle reaction be interpreted. The transition to another translation As the steering wheel angle increases, so does an increasing wheel steering angle entail, as well as a decreasing steering wheel angle a decreasing wheel steering angle must result.

The inventive method for operating a steering system of a motor vehicle is preferably implemented as a computer program on a control unit of the steering system or the superposition steering system, with other solutions come of course in question. For this purpose, the computer program is stored in a memory element of the control unit. By processing on a microprocessor of the controller Ver drive running. The computer program can be stored on a computer-readable data carrier (floppy disk, CD, DVD, hard disk, USB memory stick or the like) or an Internet server as a computer program product and be transferred from there into the memory element of the control unit. Such a computer program or computer program product with program code means is specified in claim 8 or claim 9.

claim 10 relates to a superposition steering system of a motor vehicle. Below is a principle with reference to the drawing embodiment of the invention.

Short description of drawings

It shows:

1 a schematic representation of a superposition steering system;

2 a simplified diagram of vehicle trajectories due to a change in speed at constant steering wheel angle;

3 a simplified block diagram of a module for detecting a state of a cornering of a vehicle with at least approximately constant radius of curvature;

4 a simplified block diagram of a module for adjusting the steering ratio to the current vehicle speed after completion of a constant cornering; and

5 a highly simplified diagram regarding the setting of a modified steering ratio.

Preferred embodiment

1 shows a superposition steering system 1 (Active Front Steering / AFS) of a motor vehicle, not shown. The overlay steering system 1 has a steering wheel 2 trained steering handle on. The steering wheel 2 is over a propeller shaft 3 with a steering gear 4 connected. The steering gear 4 serves to a rotation angle of the propeller shaft 3 in a wheel steering angle δ _Fm of steerable wheels 5a . 5b implement the motor vehicle. The steering gear 4 has a rack 6 and a pinion 7 on, to which the propeller shaft 3 attacks. The overlay steering system 1 also includes overlay means 8th one as an electric motor 9 trained actuator or overlay angle plate and driven by this superposition gear 10 exhibit. The superposition gearbox 10 is designed as a planetary gear. In further embodiments, the superposition gear could 10 Also be designed as a wave gear or the like. Through the steering wheel 2 is a steering wheel angle δ _S as a measure of a desired wheel steering angle δ _{Fm of} the steerable wheels 5a . 5b of the motor vehicle specified. With the help of the electric motor 9 Then, a superposition angle or additional angle δ _{M is} generated and by the superposition gear 10 superimposed with the steering wheel angle δ _S. The additional angle δ _M is basically generated to improve the driving dynamics of the motor vehicle or the comfort. The sum of steering wheel angle δ _S and additional angle δ _M gives the input angle of the steering gear 4 or in the present embodiment, the pinion angle δ _G.

The overlay means 8th could subordinate the superposition steering system 1 in a further embodiment, not shown, additionally having a servo drive as a further steering actuator, which serves in particular the variable torque assistance.

The overlay steering system 1 has an electronic control unit 11 which, inter alia, for controlling the additional angle δ _M and the output torque of the electric motor 9 serves. On the electronic control unit 11 For this purpose, a control process takes place, which as a control structure or as a computer program on a microprocessor, not shown, of the control unit 11 is executed. The electric motor 9 is with an electrical drive signal δ _Md , which the setpoint of the electric motor 9 to be generated additional angle δ _M corresponds, driven. The control or regulation of the electric motor 9 takes place as a function of the vehicle speed v _{x of} the motor vehicle, ie the gear ratio i _v between the steering wheel angle δ _S and the pinion angle δ _G or the wheel steering angle δ _{Fm of} the wheels 5a . 5b is set by the superposition of the steering wheel angle δ _S with different, speed-dependent additional angles δ _M as a function of the vehicle speed v _x . This makes it possible, for example, at low vehicle speeds v _{x to} specify a relatively small transmission ratio i _v , in which a relatively small rotation of the steering wheel 2 to a relatively large wheel steering angle δ _{Fm of} the wheels 5a . 5b leads. Likewise, for reasons of stability, it is conceivable for a high vehicle speed v _{x to} specify a relatively large transmission ratio i _v .

So that the above-mentioned control functions can be performed, receives the control unit 11 as input signal, the current vehicle speed v _x (eg via the CAN bus of the motor vehicle). In addition, the superposition steering system points 1 sensors 12a . 12b . 12c which measure the steering wheel angle δ _S , the additional angle δ _M and the pinion angle δ _G or provide equivalent signals from which these angles δ _S , δ _M , δ _G can be determined. As in 1 indicated, the control unit 11 over the sensors 12a . 12b . 12c and other vehicle systems, not shown, inter alia with the input signals vehicle speed v _x , lateral acceleration a _y , yaw rate ψ., steering wheel angle δ _S , pinion angle δ _G , additional angle δ _M and setpoint of the additional angle δ _Md (eg as a default of other vehicle dynamics systems) provided. Alternatively or additionally, a plurality of these variables could also be calculated on the basis of the other or further input variables (for example wheel speeds, etc.), in particular with the aid of suitable models.

For the motor vehicle with the superposition steering system 1 results during cornering in the case of an acceleration or deceleration process, the problem of a changing steering ratio. The driver is forced to adjust the steering wheel angle δ _S not only due to a changing turning radius, but also due to the change of the gear ratio. If, for example, the motor vehicle accelerates in a curve with a constant radius, this leads to an indirect steering ratio. Consequently, when the steering wheel is held 2 the wheel steering angle δ _Fm reduced. In order to maintain the required wheel steering angle δ _Fm , the driver must increase the steering wheel angle δ _S. If the motor vehicle decelerates in the same situation, the driver is forced to reduce the steering wheel angle δ _S in order to maintain the desired radius.

2 shows a diagram with several different vehicle trajectories 13a . 13b . 13c a motor vehicle with the superposition steering system 1 with a change in the vehicle speed v _x at constant steering wheel angle δ _S. Straight 14 marks the beginning of the acceleration process or the deceleration process. The curve 13a represents the vehicle trajectory without speed change, ie with the desired constant radius of curvature. The curve 13b marks the trajectory resulting from the deceleration process. The curve 13c marks the trajectory resulting from the acceleration process.

des Übersetzungsverhältnisses i_v zwischen dem Lenkradwinkel δ_S und dem Radlenkwinkel δ_Fm beschränkt wird. Dadurch wird sichergestellt, dass bei wenigstens annähernd konstantem Lenkradwinkel δ_S eine Radlenkwinkeländerung aufgrund einer Lenkübersetzungsänderung zumindest stark beschränkt wird, so dass diese für den Fahrer kaum mehr spürbar ist.According to the invention, a method for operating the superposition steering system 1 proposed, in which in addition to the known functionalities and utility functions after detecting a condition of cornering of the motor vehicle with at least approximately constant radius of curvature, at least the gradient

the transmission ratio i _v between the steering wheel angle δ _S and the wheel steering angle δ _{Fm is} limited. This ensures that at least approximately constant steering wheel angle δ _S a Radlenkwinkeländerung is at least greatly limited due to a steering gear change, so that it is barely noticeable to the driver.

des Übersetzungsverhältnisses i_v zwischen dem Lenkradwinkel δ_S und dem Radlenkwinkel δ_Fm beschränkt. Somit gilt:After the detection of a first state of the cornering of the motor vehicle with an approximately constant radius of curvature, the gradient becomes

the transmission ratio i _v between the steering wheel angle δ _S and the wheel steering angle δ _Fm limited. Thus:

After the detection of a second state of the cornering of the motor vehicle with a constant turning radius, the transmission ratio i _v between the steering wheel angle δ _S and the wheel steering angle δ _{Fm is kept} at least approximately constant. Thus: i _v = const and

• – der Betrag des Lenkradwinkels δ_S über einem vorgegebenen Schwellwert ε₁ liegt,
• – die Lenkradwinkelgeschwindigkeit δ ._S in einem vorgegebenen Intervall εmin2 ≥ δ .S ≥ εmax2 liegt,
• – die Querbeschleunigung a_y des Kraftfahrzeugs in einem vorgegebenen Intervall εmin3 ≥ ay ≥ εmax3 liegt und
• – die Gierrate ψ . des Kraftfahrzeugs in einem vorgegebenen Intervall εmin4 ≥ ψ . ≥ εmax4 liegt. Danach wird ein zweites Flag Flag₂ als Ausgangssignal als auf "wahr" gesetzt, ansonsten verbleibt es auf "falsch". Die Parameter ε₁ bis ε₄ werden fahrzeugspezifisch festgelegt.

How out 3 can be seen, becomes a module 15a used for detecting the first and the second state of a cornering of the motor vehicle with at least approximately constant radius of curvature. The module receives as input values 15a the steering wheel angle δ _S , the rate of change δ. _{S of} the steering wheel angle δ _S , the lateral acceleration a _y and the yaw rate ψ .. The first state is detected when at least for a predetermined first time t _1, the amount of the steering wheel angle δ _{S is} above a predetermined threshold ε ₁ and the steering wheel angular velocity δ. _S in a given interval with ε min 2 ≥ δ. S ≥ ε Max 2 lies. Thereafter, a first flag Flag _{1 is set} as an output signal to "true", otherwise it remains "false". The second state is detected if at least for a predetermined second time interval t ₂ :

• - the amount of the steering wheel angle δ _S is above a predetermined threshold value ε _1,
• The steering wheel angular velocity δ. _S in a given interval ε min 2 ≥ δ. S ≥ ε Max 2 lies,
• - The lateral acceleration a _{y of} the motor vehicle in a predetermined interval ε min 3 ≥ a y ≥ ε Max 3 lies and
• - the yaw rate ψ. of the motor vehicle at a predetermined interval ε min 4 ≥ ψ. ≥ ε Max 4 lies. Thereafter, a second flag Flag _{2 is} set to "true" as the output, otherwise it remains "not correct". The parameters ε ₁ to ε ₄ are determined vehicle-specific.

des Übersetzungsverhältnisses i_v hängt dabei über eine erste Funktion f₁ von dem Lenkradwinkel δ_S und der Änderungsgeschwindigkeit δ ._S des Lenkradwinkels δ_S ab. Der zu stellende Sollwert des Stellwinkels δ_Md ergibt sich über eine zweite Funktion f₂ aus dem Gradient

des Übersetzungsverhältnisses i_v, dem Lenkradwinkel und der Fahrzeuggeschwindigkeit v_x. Als Ausgangssignal liefert das Modul 15b den entsprechenden, von dem Elektromotor 9 zu stellenden, Sollwert des Zusatzwinkels δ_Md. Die Funktionen f₁ und f₂ können in weiteren nicht dargestellten Ausführungsbeispielen auch als Kennfelder realisiert sein. Wie aus 5 ersichtlich, muss der Übergang auf ein anderes Übersetzungsverhältnis i_v bei zunehmendem Lenkradwinkel δ_S auch einen zunehmenden Radlenkwinkel δ_Fm zur Folge haben, ebenso wie ein abnehmender Lenkradwinkel δ_S auch einen abnehmenden Radlenkwinkel δ_Fm zur Folge haben muss. Die Eingangssignale werden von den Modulen 15a, 15b fortlaufend überwacht und der erste und zweite Zustand, sowie der Normalzustand entsprechend geschaltet.After detecting a termination of the state of the cornering of the motor vehicle with at least approximately constant turning radius over the first and second flag Flag ₁ , Flag ₂ , the gear ratio i _v between the steering wheel angle δ _S and the wheel steering angle δ _Fm again the current speed v _{x of} the motor vehicle customized. This is done as out 4 visible, via a module 15b , which as inputs the steering wheel angle δ _S , the rate of change δ. _{S of} the steering wheel angle δ _S , the vehicle speed or vehicle longitudinal speed v _x and the first and second flag Flag ₁ , Flag ₂ receives. The rate of change or the gradient

the gear ratio i _v depends on a first function f ₁ of the steering wheel angle δ _S and the rate of change δ. _{S of} the steering wheel angle δ _S from. The target value to be set of the adjusting angle δ _Md is obtained from the gradient via a second function f ₂

the gear ratio i _v , the steering wheel angle and the vehicle speed v _x . The module delivers as output signal 15b the corresponding, from the electric motor 9 to be set, setpoint of the additional angle δ _Md . The functions f ₁ and f ₂ can also be implemented as maps in further exemplary embodiments which are not illustrated. How out 5 As can be seen, the transition to another gear ratio i _v with increasing steering wheel angle δ _{S must} also result in an increasing wheel steering angle δ _Fm , just as a decreasing steering wheel angle δ _{S must} also result in a decreasing wheel steering angle δ _Fm . The input signals are from the modules 15a . 15b continuously monitored and the first and second state, as well as the normal state switched accordingly.

The inventive method for operating the superposition steering system 1 of the motor vehicle is preferably as a computer program on the control unit 11 of the superposition steering system 1 realized, with other solutions of course come into question. For this purpose, the computer program is in a memory element, not shown, of the control unit 11 saved. By processing on a microprocessor of the controller 11 the procedure is carried out. The computer program can be stored on a computer-readable data medium (floppy disk, CD, DVD, hard disk, USB memory stick or the like) or an Internet server as a computer program product and from there into the memory element of the control unit 11 be transmitted.

1

Superimposed steering system

2

steering wheel

3

propeller shaft

4

steering gear

5a, 5b

steerable bikes

6

rack

7

pinion

8th

Superimposing means

9

Superimposition actuator, electric motor

10

Superposition gear

11

electronic control unit

12a, 12b, 12c

sensors

13a, 13b, 13c

curves

14

Just

15a, 15b

modules

δ _Fm

wheel steering angle or steering angle

δ _G

pinion angle

δ _S

steering wheel angle

δ. _S

Steering wheel angle speed

δ _M

additional angle

δ _Md

setpoint the additional angle

a _y

lateral acceleration

v _x

vehicle speed

ψ.

yaw rate

Flag ₁ , flag ₂

flags

i _v

ratio

ε ₁ -ε ₄

parameter

Claims (10)

Method for operating a steering system ( 1 ) of a motor vehicle, in which by means of a steering handle ( 2 ) a steering wheel angle (δ _S ) as a measure of a desired wheel steering angle (δ _Fm ) for at least one steerable wheel ( 5a . 5b ) of the motor vehicle, in which an additional angle (δ _M ) is generated and for determining an input angle (δ _G ) of a steering gear ( 4 ) of the steering system ( 1 ) is superimposed on the steering wheel angle for realizing a variable transmission ratio (i _v ) between the steering wheel angle (δ _S ) and the wheel steering angle (δ _Fm ), which is dependent on the speed (v _x ) of the motor vehicle, and in which the input angle (δ _G ) of the steering gear ( 4 ) into a corrected wheel steering angle (δ _Fm ) for the at least one steerable wheel ( 5a . 5b ) of the motor vehicle is implemented, characterized in that after detecting a condition of cornering of the motor vehicle with at least approximately constant radius of curvature, at least the gradient of the transmission ratio (i _v ) between the steering wheel angle (δ _S ) and the wheel steering angle (δ _Fm ) is limited , A method according to claim 1, characterized in that after detection of a first state of the cornering of the motor vehicle with approximately constant radius of curvature of the gradient of the transmission ratio (i _v ) between the steering wheel angle (δ _S ) and the wheel steering angle (δ _Fm ) is limited. A method according to claim 1 or 2, characterized in that after a detection of a second state of the cornering of the motor vehicle with constant curve radius, the transmission ratio (i _v ) between the steering wheel angle (δ _S ) and the wheel steering angle (δ _Fm ) is kept at least approximately constant. A method according to claim 2 or 3, characterized in that the first state is detected when, for a predetermined first period (t ₁ ), the amount of the steering wheel angle (δ _S ) above a predetermined threshold (ε ₁ ) and the steering wheel angular velocity (δ. _S ) is within a predetermined interval. A method according to claim 2, 3 or 4, characterized in that the second state is detected when, for a predetermined second time period: - the amount of the steering wheel angle (δ _S ) is above a predetermined threshold value (ε ₁ ), - the steering wheel angular velocity (δ _S ) is within a predetermined interval, - the lateral acceleration (a _y ) of the motor vehicle is within a predetermined interval and - the yaw rate (ψ) of the motor vehicle is within a predetermined interval. Method according to one of claims 1 to 5, characterized in that after detection of a termination of the state of the cornering of the motor vehicle with at least approximately constant radius of curvature, the gear ratio (i _v ) between the steering wheel angle (δ _S ) and the wheel steering angle (δ _Fm ) again the current speed (v _x ) of the motor vehicle is adjusted. A method according to claim 6, characterized in that the gradient of the transmission ratio (i _v) (in re-adapting to the current speed (v _x) of the motor vehicle as a function of the current steering wheel angle (δ _S) and the current steering wheel angular velocity δ. _S ). Computer program with program code means for carrying out a method according to one of Claims 1 to 7, when the program is stored on a microprocessor of a computer, in particular on a control unit ( 11 ) of a superposition steering system ( 1 ), is performed. A computer program product comprising program code means stored on a computer-readable medium for carrying out a method according to one of claims 1 to 7, when the program is stored on a microprocessor of a computer, in particular on a control unit ( 11 ) of a superposition steering system ( 1 ), is performed. Overlapping steering system ( 1 ) of a motor vehicle, with - a steering handle ( 2 ) for specifying a steering wheel angle (δ _S ) as a measure of a desired wheel steering angle (δ _Fm ) for at least one steerable wheel ( 5a . 5b ) of the motor vehicle, - a steering gear ( 4 ), which determines the steering wheel angle (δ _S ) in the wheel steering angle (δ _Fm ) of the at least one steerable wheel ( 5a . 5b ) of the motor vehicle, and overlay means ( 8th ) for generating an additional angle (δ _M ) by an additional angle adjuster ( 9 ) and for generating an input angle (δ _G ) of the steering gear ( 4 ) from a superposition of the steering wheel angle (δ _S ) with the additional angle ( δ _M ), wherein the additional angle plate ( 9 ) via a control unit ( 11 ), and wherein on the control unit ( 11 ) a method according to one of claims 1 to 7 is executed.