DE102019128447A1 - Method for determining an oversteering index as a measure of the oversteering of a vehicle - Google Patents

Abstract

The invention relates to a method for determining an oversteer index as a measure for the oversteering of a vehicle, the oversteer index depending on a yaw rate deviation of an actual yaw rate from a target yaw rate and a float angle deviation of an actual float angle from a target -Swimming angle and- a slip angle speed deviation of an actual slip angle speed from a target slip angle speed is determined.

Description

The invention relates to a method for determining an oversteer code as a measure of the oversteer of a vehicle. The invention also relates to a method for regulating an actual variable that influences the driving behavior of a motor vehicle. Another object of the invention is a vehicle dynamics control system with a processor unit.

Driving dynamics control systems are used in motor vehicles in order to avoid undesirable driving behavior, such as oversteering, for example. Oversteer refers to the behavior of a vehicle in bends in which the slip angle on the rear wheels is greater than on the front wheels. The rear pushes outwards, the steering angle is less than it would correspond to the curve radius. For this purpose, known vehicle dynamics control systems undertake targeted interventions in the control of a rear axle steering, a drive torque distribution or a roll torque distribution.

In order to recognize oversteering of the vehicle in such a vehicle dynamics control system, it is necessary to consider several physical variables, for example the yaw rate and the side slip angle. This results in the requirement for multi-variable control, which is associated with increased control engineering effort.

Against this background, the task arises of enabling vehicle dynamics control with a reduced control effort.

• - einer Gierratenabweichung einer Ist-Gierrate von einer Soll-Gierrate und
• - einer Schwimmwinkelabweichung eines Ist-Schwimmwinkels von einem Soll-Schwimmwinkel und
• - einer Schwimmwinkelgeschwindigkeitsabweichung einer Ist-Schwimmwinkelgeschwindigkeit von einer Soll-Schwimmwinkelgeschwindigkeit ermittelt wird.

To achieve the object, a method for determining an oversteer index is proposed as a measure for the oversteering of a vehicle, the oversteer index depending on

• - a yaw rate deviation of an actual yaw rate from a target yaw rate and
• - a deviation of the float angle of an actual float angle from a target float angle and
• - A slip angle speed deviation of an actual slip angle speed from a target slip angle speed is determined.

Another object of the invention is a vehicle dynamics control system with a processor unit which is set up to carry out the above-mentioned for determining an oversteer code as a measure for the oversteer of a vehicle.

The invention provides for the determination of an oversteer index as a measure for the oversteering of the vehicle, the oversteer index being determined as a function of the yaw rate deviation and the slip angle deviation and the slip angle speed deviation. On the basis of this override index, which can also be referred to as the override index, a simplified regulation of a control deviation in the form of the override index can be made possible instead of a multivariable control. This allows the control effort in the vehicle dynamics control system to be reduced.

mit:

ψ̇Soll

: Soll-Gierrate,

ψ̇Ist

: Ist-Gierrate,

ThdOS ψ(θ)

: vorgegebener erster Schwellwert in Abhängigkeit von der Fahrbahnneigung θ und

KOS ψ

: vorgegebener erster Normierungswert.

Die Ist-Gierrate kann durch einen Gierraten-Sensor des Fahrzeugs erfasst werden, der mit der Prozessoreinheit verbunden ist. Die Fahrbahnquerneigung kann separat geschätzt werden. Alternativ ist es möglich, die Fahrbahnneigung durch einen Neigungssensor des Fahrzeugs zu erfassen, der mit der Prozessoreinheit verbunden ist. Der erste Sollwert und der erste Normierungswert können in der Prozessoreinheit als vorgegebene Werte gespeichert sein. _{According to an advantageous embodiment of the invention, the yaw rate deviation is} determined as a first intermediate variable OS ψ̇ restricted to a predetermined value range, in particular a value range greater than 0. The first intermediate variable can be used to determine a portion of the oversteering that is proportional to the difference between the setpoint yaw rate and the actual yaw rate. The yaw rate deviation is preferably determined in the processor unit of the Vehicle dynamics control system. For the determination it is preferably provided that the following applies to the first intermediate variable: $$O{\mathrm{S.}}_{\dot{\psi }}\sim \mathrm{M.}ax\left[\frac{\left({\dot{\psi }}_{\mathrm{S.}Oll}-{\dot{\psi }}_{\mathrm{I.}st}-TH{d}_{O{\mathrm{S.}}_{\psi }}\left(\theta \right)\right)}{K_{O{\mathrm{S.}}_{\psi }}}\mathrm{,\; 0}\right],$$

With:

ψ̇Soll

: Target yaw rate,

ψ̇Is

: Actual yaw rate,

ThdOS ψ (θ)

: predetermined first threshold value as a function of the road inclination θ and

KOS ψ

: specified first normalization value.

The actual yaw rate can be detected by a yaw rate sensor of the vehicle, which is connected to the processor unit. The slope of the road can be estimated separately. Alternatively, it is possible to detect the inclination of the road by means of an inclination sensor of the vehicle which is connected to the processor unit. The first setpoint value and the first normalization value can be stored in the processor unit as predetermined values.

mit:

βSoll

: Soll-Schwimmwinkel und

βIst

: Ist-Schwimmwinkel.

Gemäß einer vorteilhaften Ausgestaltung der Erfindung wird die Schwimmwinkelgeschwindigkeitsabweichung als eine auf einen vorgegebenen Wertebereich, insbesondere einen Wertebereich von 0 bis 1, beschränkte dritte Zwischengröße OS_β bestimmt. Das Bestimmen der Schwimmwinkelgeschwindigkeitsabweichung erfolgt bevorzugt in der Prozessoreinheit des Fahrdynamikregelsystems. Durch die dritte Zwischengröße kann ein Anteil des Übersteuerns bestimmt werden, der proportional zur Differenz der Soll-Schwimmwinkelgeschwindigkeit und der Ist-Schwimmwinkelgeschwindigkeit ist. Das Bestimmen der Schwimmwinkelgeschwindigkeitsabweichung erfolgt bevorzugt in der Prozessoreinheit des Fahrdynamikregelsystems. Zur Bestimmung ist bevorzugt vorgesehen, dass für die dritte Zwischengröße gilt: $$O{S}_{\dot{\beta }}\sim Max\left(\frac{\left({\dot{\beta }}_{Soll}-{\dot{\beta }}_{Ist}-Th{d}_{O{S}_{\dot{\beta }}}\left(\theta \right)\right)}{K_{O{S}_{\dot{\beta }}}}\mathrm{,0}\right)$$

mit:

β̇̇SOll

: Soll-Schwimmwinkelgeschwindigkeit,

β̇̇ist

: Ist- Schwimmwinkelgeschwindigkeit,

ThdOS β(θ)

: vorgegebener zweiter Schwellwert in Abhängigkeit von der Fahrbahnneigung θ und

KOS β̇

: vorgegebener zweiter Normierungswert.

Gemäß einer vorteilhaften Ausgestaltung der Erfindung wird die Übersteuer-Kennzahl Idx_os in Abhängigkeit von der ersten Zwischengröße OS_ψ̇ und der zweiten Zwischengröße OS_β und der dritten Zwischengröße OS_β bestimmt gemäß $$Id{x}_{OS}=Max\left(O{S}_{\beta },O{S}_{\dot{\beta }}\left(O{S}_{\dot{\psi }}-f\left(O{S}_{\dot{\psi }}\right)\right)\ast O{S}_{\dot{\beta }}\right)$$

wobei
f(OS_ψ̇) eine Funktion ist, welche die erste Zwischengröße auf einen vorgegebenen Wertebereich, insbesondere einen Wertebereich von 0 bis 1, abbildet. Insofern werden die erste, zweite und dritte Zwischengröße überblendet, um die Übersteuer-Kennzahl zu erhalten. Die zweite und dritte Zwischengröße sind bereits auf einen vorgegebenen Wertebereich, insbesondere einen Wertebereich zwischen 0 und 1, beschränkt. Bei der Ermittlung der ersten Zwischengröße ist hingegen ein größerer Wertebereich zugelassen. Daher wird die erste Zwischengröße durch die Funktion f(OS_ψ̇) auf einen vorgegebenen Wertebereich, insbesondere einen Wertebereich von 0 bis 1, abgebildet, so dass sich die Empfindlichkeit für große Gierratenabweichungen reduziert. Durch eine Multiplikation der Differenz aus der ersten Zwischengröße und der Funktion f(OS_ψ̇) mit der dritten Zwischengröße erhöht sich der Einfluss der dritten Zwischengröße mit steigernder Differenz aus der ersten Zwischengröße und der Funktion f(OS_ψ̇). Damit kann bei einem Übersteuern mit starkem Gegenlenken noch ein schnelles Eindrehen des Fahrzeugs auf die Übersteuer-Kennzahl abgebildet werden. Gemäß einer vorteilhaften Ausgestaltung der Erfindung wird die Soll-Gierrate und/oder der Soll-Schwimmwinkel und/oder die Soll-Schwimmwinkelgeschwindigkeit anhand eines Fahrzeugmodells, insbesondere anhand einer Simulation eines Fahrzeugmodells, bestimmt. Als Eingangsgrößen können dem Fahrzeugmodell ein Radlenkwinkel einer Vorderachse und/oder ein Radlenkwinkel einer Hinterachse und/oder eine Längsgeschwindigkeit und/oder ein Giermoment zugeführt werden.According to an advantageous embodiment of the invention, the slip angle deviation is determined as a second intermediate variable OS _β restricted to a predetermined value range, in particular a value range from 0 to 1. The second intermediate variable can be used to determine a proportion of the oversteering that is proportional to the difference between the target float angle and the actual float angle. The determination of the slip angle deviation is preferably carried out in the processor unit of the vehicle dynamics control system. For the determination it is preferably provided that the following applies to the second intermediate variable: $$O{\mathrm{S.}}_{\beta }=f\left({\beta }_{\mathrm{S.}Oll}-{\beta }_{\mathrm{I.}st}\right),$$

With:

βset

: Target slip angle and

βis

: Actual slip angle.

According to an advantageous embodiment of the invention, the slip angle velocity deviation is determined as a third intermediate variable OS _β restricted to a predetermined value range, in particular a value range from 0 to 1. The determination of the slip angle speed deviation is preferably carried out in the processor unit of the vehicle dynamics control system. The third intermediate variable can be used to determine a portion of the oversteer that is proportional to the difference between the setpoint slip angle speed and the actual slip angle speed. The determination of the slip angle speed deviation is preferably carried out in the processor unit of the vehicle dynamics control system. For the determination it is preferably provided that the following applies to the third intermediate variable: $$O{\mathrm{S.}}_{\dot{\beta }}\sim \mathrm{M.}ax\left(\frac{\left({\dot{\beta }}_{\mathrm{S.}Oll}-{\dot{\beta }}_{\mathrm{I.}st}-TH{d}_{O{\mathrm{S.}}_{\dot{\beta }}}\left(\theta \right)\right)}{K_{O{\mathrm{S.}}_{\dot{\beta }}}}\mathrm{,\; 0}\right)$$

With:

β̇̇SOll

: Target slip angle speed,

β̇̇ist

: Actual slip angle velocity,

ThdOS β (θ)

: predefined second threshold value as a function of the road gradient θ and

KOS β̇

: specified second normalization value.

According to an advantageous embodiment of the invention, the override characteristic number Idx _{os is} determined according to the first intermediate _variable OS ψ̇ and the second intermediate _{variable OS β} and the third intermediate _{variable OS β} $$\mathrm{I.}d{x}_{O\mathrm{S.}}=\mathrm{M.}ax\left(O{\mathrm{S.}}_{\beta },O{\mathrm{S.}}_{\dot{\beta }}\left(O{\mathrm{S.}}_{\dot{\psi }}-f\left(O{\mathrm{S.}}_{\dot{\psi }}\right)\right)\ast O{\mathrm{S.}}_{\dot{\beta }}\right)$$

in which
f (OS _ψ̇ ) is a function which maps the first intermediate variable to a specified range of values, in particular a range of values from 0 to 1. In this respect, the first, second and third intermediate variables are blended in order to obtain the override key figure. The second and third intermediate variables are already limited to a predefined range of values, in particular a range of values between 0 and 1. When determining the first intermediate variable, however, a larger range of values is permitted. _{The first intermediate variable is therefore mapped} to a predefined value range, in particular a value range from 0 to 1, by the function f (OS ψ̇), so that the sensitivity to large yaw rate deviations is reduced. By multiplying the difference between the first intermediate _variable and the function f (OS ψ̇) by the third intermediate variable, the influence of the third intermediate variable increases as the difference between the first intermediate _{variable and the function f (OS ψ} ̇) increases. In this way, in the event of oversteer with strong countersteering, a rapid turning of the vehicle can still be mapped to the oversteer code. According to an advantageous embodiment of the invention, the set yaw rate and / or the set float angle and / or the set float angle speed is determined on the basis of a vehicle model, in particular on the basis of a simulation of a vehicle model. A wheel steering angle of a front axle and / or a wheel steering angle of a rear axle and / or a longitudinal speed and / or a yaw moment can be fed to the vehicle model as input variables.

mit:

ax

: Längsbeschleunigung,

ψ̇

: Gierrate,

g

: Erdbeschleunigung,

φ

: Fahrbahnlängssteigung,

ay

: Querbeschleunigung und

θ

: Fahrbahnquerneigung.

Durch die Bestimmung der genannten Werte mittels der genannten Bewegungsgleichungen wird es möglich, im Fahrzeug üblicherweise messtechnisch nicht erfasste bzw. nicht erfassbare Größen zu erhalten. Anhand des Ist-Schwimmwinkels sowie der Längsgeschwindigkeit v_x und der Quergeschwindigkeit v_y kann die Bestimmung der Schwimmwinkelgeschwindigkeit erfolgen. Die Integration der Bewegungsgleichungen ermöglicht es, auch bei einem großen Schwimmwinkel eine zuverlässige Angabe der Schwimmwinkelgeschwindigkeit zu erhalten. Zur Gewinnung der Schwimmwinkelgeschwindigkeit β̇̇̇̇ kann die Bewegungsgleichung $$\dot{\beta }=\frac{a_y}{\text{cos}\left(\beta \right)\ast \left|v\right|}-\dot{\psi }$$

mit:

ay

: Querbeschleunigung,

β

: Schwimmwinkel,

v

: Horizontalgeschwindigkeit,

und

 

ψ̇

: Gierrate

genutzt werden, wobei die Horizontalgeschwindigkeit der Vektor bestehend aus der Längsgeschwindigkeit v_x und der Quergeschwindigkeit v_y ist.According to an advantageous embodiment of the invention, a longitudinal speed v _x and a transverse speed v _{y are} calculated to determine the actual float angle, in particular by integrating the equations of motion $${\dot{v}}_x=a_x+v_y\dot{\psi }+G\text{sin}\phi \text{and}{\dot{v}}_y=a_y-v_x\dot{\psi }-G\text{sin}\theta$$

With:

ax

: Longitudinal acceleration,

ψ̇

: Yaw rate,

G

: Acceleration due to gravity,

φ

: Longitudinal slope of the road,

ay

: Lateral acceleration and

θ

: Cross slope of the road.

By determining the values mentioned by means of the equations of motion mentioned, it is possible to obtain variables that are usually not recorded or that cannot be recorded in the vehicle. Based on the actual float angle and the longitudinal speed v _x and the The lateral velocity v _y can be used to determine the velocity of the sideslip angle. The integration of the equations of motion makes it possible to obtain a reliable indication of the velocity of the slip angle even with a large slip angle. The equation of motion can be used to obtain the slip angle velocity β̇̇̇̇ $$\dot{\beta }=\frac{a_y}{\text{cos}\left(\beta \right)\ast \left|v\right|}-\dot{\psi }$$

With:

ay

: Lateral acceleration,

β

: Side slip angle,

v

: Horizontal speed,

and

ψ̇

: Yaw rate

can be used, the horizontal speed being the vector consisting of the longitudinal speed v _x and the lateral speed v _y .

The invention also relates to a method for regulating an actual variable influencing the driving behavior of a vehicle, in particular a motor vehicle, characterized in that an oversteer code is determined according to a method according to one of the preceding claims and a manipulated variable is set as a function of the oversteer code .

Another subject matter of the invention is a vehicle dynamics control system with a processor unit which is set up to execute such a method for controlling an actual variable that influences the driving behavior of a vehicle, in particular a motor vehicle.

In the method for regulating the manipulated variable and in the vehicle dynamics control system, the same advantages can be achieved as have already been explained in connection with the method for determining an override index.

The manipulated variable influencing the driving behavior of the vehicle is preferably an actual yaw rate and / or a float angle and / or a float angle speed. The manipulated variable is preferably a yaw moment and / or a steering angle, in particular a steering angle of a rear axle steering.

The manipulated variable is preferably set as a function of the override index in such a way that the manipulated variable has a component that is proportional to the override index.

According to an advantageous embodiment of the invention, it is provided that the manipulated variable is additionally set as a function of a control component that is a function of a setpoint variable.

• 1 ein Fahrdynamikregelsystem zur Regelung einer das Fahrverhaltens eines Fahrzeugs beeinflussenden Istgröße gemäß einem Ausführungsbeispiel der Erfindung in einem schematischen Blockdiagramm;
• 2 eine Darstellung zur Erläuterung der für das Fahrdynamikregelsystem wesentlichen Größen; und
• 3 eine Bestimmungseinheit zur Bestimmung der Übersteuer-Kennzahl gemäß einem Ausführungsbeispiel der Erfindung in einem schematischen Blockdiagramm.

Further details and advantages of the invention are to be explained below with reference to the exemplary embodiment shown in the drawings. Herein shows:

• 1 a driving dynamics control system for controlling an actual variable influencing the driving behavior of a vehicle according to an exemplary embodiment of the invention in a schematic block diagram;
• 2 a representation to explain the variables essential for the vehicle dynamics control system; and
• 3 a determination unit for determining the override code according to an embodiment of the invention in a schematic block diagram.

The representation in 1 shows a vehicle dynamics control system according to an embodiment of the invention. The driving dynamics system comprises a processor unit which is set up to execute a method for regulating an actual variable that influences the driving behavior of a vehicle. In this method, a setpoint value r is fed to a first determination unit G_F for determining a control component u_f. This control component u_f is a function of the setpoint value r, for example proportional to the setpoint value r.

According to the invention, in the method, an override code number Idx _{os is determined} in a second determination unit G_OS and a manipulated variable u is set as a function of the override code number Idx _os . For this purpose, a further control component u_c is determined in a third determination unit G_C, which follows the second determination unit G_OS, which is proportional to the override code Idx _os . The manipulated variable u is determined from the control component u_f and the control component u_c. The controlled system is in the illustration according to 1 with G_P, the disturbance variable with d. The actual variable y_m, for example a yaw rate, is fed back to the second determination unit G_OS. Another input value for the second determination unit is the setpoint value r.

In the 2 are the variables of a motor vehicle with a rear wheel that are relevant for driving dynamics control 1 and a front wheel 2 shown according to the single-track model known as such. The angle δ _H denotes the rear wheel steering angle of the rear wheel 1 and the angle δ _v denotes the front wheel steering angle of the front wheel 2 . The float angle β results as Angle between the direction of the horizontal speed v of the vehicle in the center of gravity SP and the vehicle longitudinal axis x. The horizontal speed v is the vector consisting of the longitudinal speed v _x and the transverse speed v _y . The yaw rate ψ̇ and the yaw moment M _z are determined around the center of gravity SP.

The representation in 3 shows, in a block diagram, the sequences of a method for determining an override characteristic number Idx _os according to an exemplary embodiment of the invention, which is implemented in the control unit of the vehicle dynamics control system. In this method, the oversteering index Idx _{os is used} as a measure of the oversteering of a vehicle depending on a yaw rate deviation of an actual yaw rate ψ̇ _actual from a target yaw rate ψ̇ _target and a _{slip angle deviation of an actual slip angle β actual} from a set slip angle β and a _target slip angular velocity deviation of an actual side slip angle rate beta _is determined from a target slip angle velocity beta _target.

Integriert, um den Ist-Schwimmwinkels β_Ist sowie die Horizontalgeschwindigkeit v zu erhalten.The rear wheel steering angle δ _H , the front wheel steering angle δ _v , the longitudinal speed v _x and the yaw moment M _z are mapped to a vehicle model 14th fed. Based on the vehicle model 14th the setpoint yaw rate ψ̇ _setpoint and the setpoint _{slip angle β setpoint} and the setpoint slip angle speed _{β̇ ̇setpoint are} determined and specified for further processing. The nominal float angle β _nominal and the nominal float angle speed β̇ _nominal are combined with the longitudinal speed v _x , the transverse acceleration a _y, the actual yaw rate ̇ψ̇ _actual , dr lane transverse inclination θ and the longitudinal incline φ of an integration unit 15th fed which the equations of motion $${\dot{v}}_x=a_x+v_y\dot{\psi }+G\text{sin}\phi \text{and}{\dot{v}}_y=a_y-v_x\dot{\psi }-G\text{sin}\theta$$

Integrated in order to obtain the actual float angle β _Ist and the horizontal speed v.

genutzt.To calculate the actual slip angle velocity β̇ _Ist in the calculation unit 16 the equilibrium of movement $$\dot{\beta }=\frac{a_y}{\text{cos}\left(\beta \right)\ast \left|v\right|}-\dot{\psi }$$

used.

mit:

ψ̇Soll

: Soll-Gierrate,

ψ̇Ist

: Ist-Gierrate,

ThdOS ψ(θ)

: vorgegebener erster Schwellwert in Abhängigkeit von der Fahrbahnneigung θ und

KOS ψ

: vorgegebener erster Normierungswert.

Die Schwimmwinkelabweichung wird in einer zweiten Zwischenwerteinheit 12 als eine auf einen vorgegebenen Wertebereich von 0 bis 1 beschränkte zweite Zwischengröße OS_β bestimmt, wobei für die zweite Zwischengröße gilt: $$O{S}_{\beta }=f\left({\beta }_{Soll}-{\beta }_{Ist}\right),$$

mit:

βSoll

: Soll-Schwimmwinkel und

βlst

: Ist-Schwimmwinkel.

Die Schwimmwinkelgeschwindigkeitsabweichung wird in einer dritten Zwischenwerteinheit 13 als eine auf einen vorgegebenen Wertebereich von 0 bis 1 beschränkte dritte Zwischengröße OS_β bestimmt, wobei für die dritte Zwischengröße gilt: $$O{S}_{\dot{\beta }}\sim Max\left[\frac{\left({\dot{\beta }}_{Soll}-{\dot{\beta }}_{Ist}-Th{d}_{O{S}_{\dot{\beta }}}\left(\theta \right)\right)}{K_{O{S}_{\dot{\beta }}}}\mathrm{,0}\right]$$

mit:

β̇Soll

: Soll-Schwimmwinkelgeschwindigkeit,

β̇Ist

: Ist- Schwimmwinkelgeschwindigkeit,

ThdOS β(θ)

: vorgegebener zweiter Schwellwert in Abhängigkeit von der Fahrbahnneigung θ und

KOS β̇

: vorgegebener zweiter Normierungswert.

Die erste, zweite und dritte Zwischengröße OS_ψ̇, OS_β, OS_β̇̇ werden nachfolgend überblendet, um die Übersteuer-Kennzahl Idx_os zu erhalten. Für die Übersteuer-Kennzahl Idx_os gilt: $$Id{x}_{OS}=Max\left(O{S}_{\beta },O{S}_{\beta },\left(O{S}_{\dot{\psi }}-f\left(O{S}_{\dot{\psi }}\right)\right)\ast O{S}_{\dot{\beta }}\right)$$

Während die zweite und dritte Zwischengröße OS_β, OS_β bereits auf den Wertebereich [0,1] normiert sind, ist für die erste Zwischengröße OS_ψ̇, ein größerer Wertebereich zugelassen.The yaw rate deviation is in a first intermediate size unit 11 _{as a first intermediate variable} OS ψ̇ restricted to a specified range of values greater than 0, where the following applies to the first intermediate variable: $$O{\mathrm{S.}}_{\dot{\psi }}\sim \mathrm{M.}ax\left[\frac{\left({\dot{\psi }}_{\mathrm{S.}Oll}-{\dot{\psi }}_{\mathrm{I.}st}-TH{d}_{O{\mathrm{S.}}_{\psi }}\left(\theta \right)\right)}{K_{O{\mathrm{S.}}_{\psi }}}\mathrm{,\; 0}\right],$$

With:

ψ̇Soll

: Target yaw rate,

ψ̇Is

: Actual yaw rate,

ThdOS ψ (θ)

: predetermined first threshold value as a function of the road inclination θ and

KOS ψ

: specified first normalization value.

The slip angle deviation is shown in a second intermediate value unit 12th _{is determined as a second intermediate variable OS β} restricted to a predetermined value range from 0 to 1, where the following applies to the second intermediate variable: $$O{\mathrm{S.}}_{\beta }=f\left({\beta }_{\mathrm{S.}Oll}-{\beta }_{\mathrm{I.}st}\right),$$

With:

βset

: Target slip angle and

βlst

: Actual slip angle.

The slip angle speed deviation is calculated in a third intermediate value unit 13th _{is determined as a third intermediate variable OS β} restricted to a specified range of values from 0 to 1, where the following applies to the third intermediate variable: $$O{\mathrm{S.}}_{\dot{\beta }}\sim \mathrm{M.}ax\left[\frac{\left({\dot{\beta }}_{\mathrm{S.}Oll}-{\dot{\beta }}_{\mathrm{I.}st}-TH{d}_{O{\mathrm{S.}}_{\dot{\beta }}}\left(\theta \right)\right)}{K_{O{\mathrm{S.}}_{\dot{\beta }}}}\mathrm{,\; 0}\right]$$

With:

β̇set

: Target slip angle speed,

β̇is

: Actual slip angle velocity,

ThdOS β (θ)

: predefined second threshold value as a function of the road gradient θ and

KOS β̇

: specified second normalization value.

The first, second and third intermediate _variables OS ψ̇, OS _β , OS _β̇̇ are then superimposed in order to obtain the override index Idx _os . The following applies to the override key figure Idx _os: $$\mathrm{I.}d{x}_{O\mathrm{S.}}=\mathrm{M.}ax\left(O{\mathrm{S.}}_{\beta },O{\mathrm{S.}}_{\beta },\left(O{\mathrm{S.}}_{\dot{\psi }}-f\left(O{\mathrm{S.}}_{\dot{\psi }}\right)\right)\ast O{\mathrm{S.}}_{\dot{\beta }}\right)$$

While the second and third intermediate variable OS _β , OS _{β are} already normalized to the value range [0.1], a larger value range is permitted _{for the first intermediate variable OS ψ̇.}

By a characteristic 17th the sensitivity to large deviations is reduced. The mapping of the first intermediate _variable OS ψ̇, by the characteristic 17th is subtracted from the first intermediate _variable OS ψ̇, see subtractor 18th . The result of this subtraction is multiplied by the third intermediate variable, see multiplier 19th . With increasing deviation between the first intermediate _variable OS ψ̇ and the mapping of the first intermediate _variable OS ψ̇ by the characteristic 17th the influence of the third intermediate _{variable OS β̇ is} increased. This means that even in the event of oversteer with strong countersteering, a rapid turning of the vehicle is mapped _{to the oversteer index Idx os.} The override index Idx _os with its three components of the intermediate _variables OS ψ̇, OS _β , OS _β̇̇ thus leads to a simplification of the multivariable control to a regulation on a control deviation in the form of the override index Idx _OS . This reduces the control effort.

Claims (10)

Method for determining an oversteer index as a measure for the oversteering of a vehicle, the oversteer index depending on - a yaw rate deviation of an actual yaw rate from a target yaw rate and - a deviation of the float angle of an actual float angle from a target float angle and - A slip angle speed deviation of an actual slip angle speed from a target slip angle speed is determined. Procedure according to Claim 1 , characterized _{in that the yaw rate deviation is} determined as a first intermediate variable OS ψ̇ limited to a predetermined value range, in particular a value range greater than 0, with the following preferably applies to the first intermediate variable: $$O{\mathrm{S.}}_{\dot{\psi }}\sim \mathrm{M.}ax\left[\frac{\left({\dot{\psi }}_{\mathrm{S.}Oll}-{\dot{\psi }}_{\mathrm{I.}st}-TH{d}_{O{\mathrm{S.}}_{\psi }}\left(\theta \right)\right)}{K_{O{\mathrm{S.}}_{\psi }}}\mathrm{,\; 0}\right],$$

with: ψ̇ _target : target yaw rate, ψ̇ _actual : actual yaw rate, Thd _{OS ψ} (θ): specified first threshold value as a function of the road inclination θ and K _{OS ψ} : specified first normalization value. Method according to one of the preceding claims, characterized _{in that the slip angle deviation is determined as a second intermediate variable OS β} restricted to a predetermined value range, in particular a value range from 0 to 1, with the following preferably applies to the second intermediate variable: $$O{\mathrm{S.}}_{\beta }=f\left({\beta }_{\mathrm{S.}Oll}-{\beta }_{\mathrm{I.}st}\right),$$

with: β _target : target float angle and β _actual : actual float angle. Method according to one of the preceding claims, characterized _{in that the slip angle velocity deviation is determined as a third intermediate variable OS β} restricted to a predetermined value range, in particular a value range from 0 to 1, with the following preferably applies to the third intermediate variable: $$O{\mathrm{S.}}_{\dot{\beta }}\sim \mathrm{M.}ax\left(\frac{\left({\dot{\beta }}_{\mathrm{S.}Oll}-{\dot{\beta }}_{\mathrm{I.}st}-TH{d}_{O{\mathrm{S.}}_{\dot{\beta }}}\left(\theta \right)\right)}{K_{O{\mathrm{S.}}_{\dot{\beta }}}}\mathrm{,\; 0}\right)$$

with: β̇ _target : target slip angle speed, β̇ _actual : actual slip angle speed, Thd _{OS β̇} (θ): predetermined second threshold value as a function of the road inclination θ and K _{OS β̇} : specified second normalization value. Procedure according to the Claims 2 , 3 and 4th , characterized in that the override index Idx _{os is determined} as a function of the first intermediate _variable OS ψ̇, and the second intermediate _{variable OS β} and the third intermediate _{variable OS β} according to $$\mathrm{I.}d{x}_{Os}=\mathrm{M.}ax\left(O{\mathrm{S.}}_{\beta },O{\mathrm{S.}}_{\beta },\left(O{\mathrm{S.}}_{\dot{\psi }}-f\left(O{\mathrm{S.}}_{\dot{\psi }}\right)\right)\ast O{\mathrm{S.}}_{\dot{\beta }}\right)$$

where f (OS _ψ̇ ) is a function which maps the first intermediate variable to a specified range of values, in particular a range of values from 0 to 1. Method according to one of the preceding claims, characterized in that the setpoint yaw rate and / or the setpoint slip angle and / or the setpoint slip angle speed is determined using a vehicle model, in particular using a simulation of a vehicle model. Method according to one of the preceding claims, characterized in that to determine the actual side slip angle, a longitudinal speed v _x and a transverse speed v _{y are} calculated, in particular by integrating the equations of motion $${\dot{v}}_x=a_x+v_y\dot{\psi }+G\text{sin}\phi \text{and}{\dot{v}}_y=a_y-v_x\dot{\psi }-G\text{sin}\theta$$

with: a _x : longitudinal acceleration, ψ̇: yaw rate, g: acceleration due to gravity, φ: longitudinal slope of the road, a _y : lateral acceleration and θ: transverse slope of the road. Method for regulating an actual variable influencing the driving behavior of a vehicle, characterized in that an oversteer characteristic number is determined according to a method according to one of the preceding claims and a manipulated variable is set as a function of the oversteer characteristic number. Procedure according to Claim 8 , characterized in that the manipulated variable is additionally set as a function of a control component which is a function of a setpoint variable. Vehicle dynamics control system with a processor unit which is set up to carry out a method according to one of the preceding claims.

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