Method for controlling yaw and transversal dynamics in a road vehicle
View Patent ↗For the purpose of controlling the yaw dynamics and lateral dynamics in a road vehicle with electrically controlled four-wheel steering, in the case of which the setting of the front axle steer angle δ v and of the rear axle steer angle δ h is performed by means of mutually decoupled control loops, a desired value δ vsoll for the lateral force S v to be built up at the front axle is determined in the control loop assigned to the front axle and, for this desired value S vsoll , the value of the slip angle, linked to the desired value S vsoll , is determined as desired value α vsoll from an S v (α v ) characteristic representing the dependence of the lateral force S v , to be built up at the front axle, on the slip angle α v . In the control loop assigned to the rear axle, a desired value S hsoll for the lateral force S h to be built up at the rear axle is determined in a control process in accordance with a controller law of the form S hsoll = l v · m · v x L · [ Ψ . - β hsoll + k 1 · ( β h - β - hsoll ) ] and, for this desired value S hsoll , the value of the slip angle, linked to the desired value S hsoll , is determined as desired value α hsoll from an S h (α h ) characteristic. These desired values α vsoll and α hsoll are used to determine the desired values δ vsoll and δ hsoll of the steer angle, taking account of an estimated value of the sideslip angle β at the center of gravity of the vehicle, the position of the center of gravity and measured or estimated values of the yaw velocity {dot over (Ψ)} and of the longitudinal speed v x of the vehicle.
1. A method
for controlling yaw dynamics and lateral dynamics in a road vehicle having a first axle and a second axle comprising;
determining a desired steer angle;
calculating a desired front axle value signal for input to a first controller;
calculating a desired rear axle value signal for input to a second controller;
generating a first drive signal via said first controller for driving an electrically drivable front steer-angle actuator;
generating a second drive signal via said second controller for driving an electrically drivable rear steer-angle actuator;
determining a desired value S vsoll for a lateral force S v to be built up at said front axle in a control process in a control loop assigned to said front axle;
determining for said desired value S vsoll a desired value δ vsoll of a front axle steering angle by a relationship of a form
δ
vsoll
=
-
β
+
l
v
·
Ψ
.
v
x
+
α
vsoll
,
wherein l v being a distance from a center of gravity of said vehicle to said front axle, β being a sideslip angle, {dot over (Ψ)} being a yaw velocity, α vsoll being a desired value of a slip angle at said front axle, and V x being a longitudinal speed of said road vehicle;
determining a desired value S hsoll for a lateral force S h to be built up at said rear axle in a control process by a relationship of a form
S
hsoll
=
l
v
·
m
·
v
x
L
·
[
Ψ
.
-
β
.
hsoll
+
k
1
·
(
β
h
-
β
-
hsoll
)
]
in a control loop assigned to said rear axle, wherein m being a mass of said vehicle, L being a wheelbase of said vehicle, β hsoll being a desired slideslip angle of said vehicle in a region of said rear axle, and β h being a slideslip angle of said vehicle in said region of said rear axle, and β h being a first controller gain; and
determining for said desired value S hsoll a value of a rear axle steering angle δ hsoll by a relationship of a form
δ
hsoll
=
-
β
-
l
h
·
Ψ
.
v
x
+
α
hsoll
.
2. The method of claim 1 , wherein said desired value S vsoll of said lateral force to be built up at said front axle being determined in a control process by a relationship of a form
S
vsoll
=
l
h
·
m
·
v
x
L
·
[
Ψ
.
-
β
.
vsoll
+
k
2
·
(
β
v
-
β
vsoll
)
]
,
wherein m being a mass of said vehicle, l h being a distance from a center of gravity of said vehicle to said rear axle, β vsoll being a desired slideslip angle of said vehicle in a region of said front axle, β v being a slideslip angle of said vehicle in said region of said front axle, and k 2 being a second controller gain.
3. The method of claim 2 , wherein said desired value α vsoll of said slip angle α v at said front axle being obtained from a linear relationship of a form
δ
vsoll
=
S
vsoll
C
v
,
and wherein C v being an estimated front wheel slip stiffness.
4. The method of claim 2 , wherein said desired value α hsoll of said slip angle α h at said rear axle being obtained from a linear relationship of a form
δ
hsoll
=
S
hsoll
C
h
,
and wherein C h being an estimated rear wheel slip stiffness.
5. The method of claim 1 , wherein said desired value S vsoll of a lateral force to be built up at said front axle being determined in a control process by a relationship of a form
S
vsoll
=
l
h
·
m
·
a
y
L
+
J
z
L
·
[
Ψ
¨
soll
-
k
s
·
(
Ψ
.
-
Ψ
.
soll
)
]
,
wherein J z being a moment of inertia, {dot over (Ψ)} soll being a desired yaw velocity, and k 3 being a third controller gain.
6. The method of claim 5 , wherein said desired value α vsoll of said slip angle α v at said front axle being obtained from a linear relationship of a form
δ
vsoll
=
S
vsoll
C
v
,
and wherein C v being an estimated front wheel slip stiffness.
7. The method of claim 5 , wherein said desired value α hsoll of said slip angle α h at said rear axle being obtained from a linear relationship of a form
δ
hsoll
=
S
hsoll
C
h
,
and wherein C h being an estimated rear wheel slip stiffness.
8. The method of claim 1 , wherein said desired value α vsoll of said slip angle α v at said front axle being obtained from a linear relationship of a form
δ
vsoll
=
S
vsoll
C
v
,
and wherein C v being an estimated front wheel slip stiffness.
9. The method of claim 1 , wherein said desired value αhsoll of said slip angle α h at said rear axle being obtained from a linear relationship of a form
δ
hsoll
=
S
hsoll
C
h
,
and wherein C h being an estimated rear wheel slip stiffness.
10. The method of claim 1 , wherein said desired value S vsoll of said lateral force to be built up at said front axle being determined in a control process by a relationship of a form
S
vsoll
=
l
h
·
m
·
v
x
L
·
[
Ψ
.
-
β
.
vsoll
+
k
2
·
(
β
v
-
β
vsoll
)
]
,
wherein l h being a distance from a center of gravity of said vehicle to said rear axle, β vsoll being a desired slideslip angle of said vehicle in a region of said front axle, β v being a slideslip angle of said vehicle in said region of said front axle, and k 2 being a second controller gain;
wherein said front steer-angle actuator is individually assigned to said first axle and said rear steer-angle actuator is individually assigned to said second axle;
wherein said control loop assigned to said front axle and said control loop assigned to said rear axle are decoupled from one another;
wherein said desired front axle value signal and said desired rear axle value signal are generated by a reference model, said reference model being implemented by an electronic computer from a processing of at least one output signal, representing a driver's wish, from a steering element position sensor, and of a sensor output signal characteristic of an operating state of said vehicle.
11. An apparatus for controlling yaw dynamics and lateral dynamics in a road vehicle having a first axle and a second axle comprising:
a first steering device for said front axle;
a second steering device for said rear axle;
a first steer angle actuator for said front axle;
a second steer angle actuator for said rear axle; and
at least one lateral acceleration sensor;
wherein a first control mode for a desired value S vsoll of a lateral force at said front axle being obtained from a relationship of a form
S
vsoll
=
l
h
·
m
·
v
x
L
·
[
Ψ
.
-
β
.
vsoll
+
k
2
·
(
β
v
-
β
vsoll
)
]
,
and a second control mode for said desired value S vsoll being obtained from a relationship of a form
S
vsoll
=
l
h
·
m
·
a
y
L
+
J
z
L
·
[
Ψ
.
soll
-
k
3
·
(
Ψ
.
-
Ψ
.
vsoll
)
]
,
wherein m being a mass of said vehicle, L being a wheelbase of said vehicle, l h being a distance from a center of gravity of said vehicle to said rear axle, β being a sideslip angle, a y being a lateral acceleration, J z being a moment of inertia, and V x being a longitudinal speed of said road vehicle, {dot over (Ψ)} being a yaw velocity, {dot over (Ψ)} soll being a desired yaw velocity, k 2 being a second controller gain, and k 3 being a third controller gain.
12. An apparatus for controlling yaw dynamics and lateral dynamics in a road vehicle having a first axle and a second axle comprising:
a first steering device for said front axle;
a second steering device for said rear axle;
a first steer angle actuator for said front axle;
a second steer angle actuator for said rear axle; and
at least one lateral acceleration sensor;
wherein a first control mode for a desired value S vsoll of a lateral force at said front axle being obtained from a relationship of a form
S
vsoll
=
l
h
·
m
·
v
x
L
·
[
Ψ
.
-
β
.
vsoll
+
k
2
·
(
β
v
-
β
vsoll
)
]
,
and a second control mode for said desired value S vsoll being obtained from a relationship of a form
S
vsoll
=
l
h
·
m
·
a
y
L
+
J
z
L
·
[
Ψ
.
soll
-
k
3
·
(
Ψ
.
-
Ψ
.
vsoll
)
]
,
wherein m being a mass of said vehicle, L being a wheelbase of said vehicle, l h being a distance from a center of gravity of said vehicle to said rear axle, β being a sideslip angle, a y being a lateral acceleration, J z being a moment of inertia, and V x being a longitudinal speed of said road vehicle, {dot over (Ψ)} being a yaw velocity, {dot over (Ψ)} soll being a desired yaw velocity, k 2 being a second controller gain, and k 3 being a third controller gain;
wherein said first control mode and second control mode being alternatively selectable.
13. The apparatus of claim 12 wherein said first control mode and said second control mode are in a first control loop;
wherein a desired value S hsoll for a lateral force S h to be built up at said rear axle being obtained from a relationship of a form
S
hsoll
=
l
v
·
m
·
v
x
L
.
[
Ψ
.
-
β
.
hsoll
+
k
1
·
(
β
h
-
β
-
hsoll
)
]
in a second control loop assigned to said rear axle, wherein β hsoll being a desired slideslip angle of said vehicle in a region of said rear axle, and β h being a slideslip angle of said vehicle in said region of said rear axle, and k 1 being a first controller gain; and
wherein for said desired value S hsoll a value of a rear axle steering angle δ hsoll being determined by a relationship of a form
δ
hsoll
=
-
β
-
l
h
·
Ψ
.
v
x
+
α
hsoll
;
wherein said first steer-angle actuator is individually assigned to said front axle and said second steer-angle actuator is individually assigned to said rear axle;
wherein said first control loop assigned to said front axle and said second control loop assigned to said rear axle are decoupled from one another;
wherein a desired front axle value signal and a desired rear axle value signal are generated by a reference model, said reference model being implemented by an electronic computer from a processing of at least one output signal, representing a driver's wish, from a steering element position sensor, and of a sensor output signal characteristic of an operating state of said vehicle.
14. An apparatus for controlling yaw dynamics and lateral dynamics in a road vehicle having a first axle and a second axle comprising:
a first steering device for said front axle;
a second steering device for said rear axle;
a first steer angle actuator for said front axle;
a second steer angle actuator for said rear axle;
at least one lateral acceleration sensor;
a reference model, wherein said reference model generating desired values for a front axle steer angle δ v and a rear axle steer angle δ h ; and
wherein an automatic switchover being performed from a control mode in which a desired value S vsoll of a lateral force at said front axle being determined as a function of a system deviation (β v −β vsoll ) of a sideslip angle in a region of said front axle, into a control mode in which a desired value S vsoll of a lateral force at said front axle being determined as a function of a system deviation ({dot over (Ψ)}−{dot over (Ψ)} soll ) of a yaw velocity when an ability of a tire to transmit lateral force being exhausted, or virtually exhausted, in an extreme range, or a rear axle steer angle actuator has failed.
15. An apparatus for controlling yaw dynamics and lateral dynamics in a road vehicle having a first axle and a second axle comprising:
a first steering device for said front axle;
a second steering device for said rear axle;
a first steer angle actuator for said front axle;
a second steer angle actuator for said rear axle; and
at least one lateral acceleration sensor;
wherein a disturbance estimator is provided for at least one of a plurality control loops provided for setting a front axle steer angle δ y and a rear axle steer angle δ h ; and
wherein a controller and a disturbance estimator which are assigned to the same controlled variable are designed using the same design model.
16. A method for controlling yaw dynamics and lateral dynamics in a road vehicle having a first axle and a second axle comprising:
determining a desired steer angle;
calculating a desired front axle value signal for input to a first controller;
calculating a desired rear axle value signal for input to a second controller;
generating a first drive signal via said first controller for driving an electrically drivable front steer-angle actuator;
generating a second drive signal via said second controller for driving an electrically drivable rear steer-angle actuator;
determining a desired value S vsoll for a lateral force S v to be built up at said front axle in a control process in a control loop assigned to said front axle;
determining a desired value of a slip angle at said front axle α vsoll from an S v (α v ) characteristic representing a dependence of said lateral force S v on a slip angle α v at said front axle;
determining for said desired value S vsoll a desired value δ vsoll of a front axle steering angle by a relationship of a form
δ
vsoll
=
-
β
+
l
v
·
Ψ
.
v
x
+
α
vsoll
,
wherein l v being a distance from a center of gravity of said vehicle to said front axle, β being a sideslip angle, {dot over (Ψ)} being a yaw velocity, and V x being a longitudinal speed of said road vehicle;
determining a desired value S hsoll for a lateral force S h to be built up at said rear axle in a control process by a relationship of a form
S
hsoll
=
l
v
·
m
·
v
x
L
.
[
Ψ
.
-
β
.
hsoll
+
k
1
·
(
β
h
-
β
-
hsoll
)
]
in a control loop assigned to said rear axle, wherein m being a mass of said vehicle, L being a wheelbase of said vehicle, β hsoll being a desired slideslip angle of said vehicle in a region of said rear axle, and β h being a slideslip angle of said vehicle in said region of said rear axle, and k 1 being a first controller gain;
determining a desired value of a slip angle at said rear axle α hsoll from an S h (α h ) characteristic representing a dependence of said lateral force S h on a slip angle α h at said rear axle; and
determining for said desired value S hsoll a value of a rear axle steering angle δ hsoll by a relationship of a form
δ
hsoll
=
-
β
-
l
h
·
Ψ
.
v
x
+
α
hsoll
;
wherein said front steer-angle actuator is individually assigned to said front axle and said rear steer-angle actuator is individually assigned to said rear axle;
wherein said control loop assigned to said front axle and said control loop assigned to said rear axle are decoupled from one another;
wherein said desired front axle value signal and said desired rear axle value signal are generated by a reference model, said reference model being implemented by an electronic computer from a processing of at least one output signal, representing a driver's wish, from a steering element position sensor, and of a sensor output signal characteristic of an operating state of said vehicle.
17. An apparatus for controlling yaw dynamics and lateral dynamics in a road vehicle having a first axle and a second axle comprising:
a first steering device for said front axle;
a second steering device for said rear axle;
a first steer angle actuator for said front axle;
a second steer angle actuator for said rear axle; and
at least one lateral acceleration sensor;
wherein a desired value S vsoll for a lateral force S v to be built up at said front axle being determined in a control process in a first control loop assigned to said front axle;
wherein a desired value of a slip angle at said front axle a vsoll being determined from an S v (α v ) characteristic representing a dependence of said lateral force S v on a slip angle α v at said front axle;
wherein for said desired value S vsoll a desired value δ vsoll of a front axle steering angle being determined by a relationship of a form
δ
vsoll
=
-
β
+
l
v
·
Ψ
.
v
x
+
α
vsoll
,
wherein l v being a distance from a center of gravity of said vehicle to said front axle, β being a sideslip angle, {dot over (Ψ)} being a yaw velocity, and V x being a longitudinal speed of said road vehicle;
wherein a desired value S hsoll for a lateral force S h to be built up at said rear axle being obtained from a relationship of a form
S
hsoll
=
l
v
·
m
·
v
x
L
.
[
Ψ
.
-
β
.
hsoll
+
k
1
·
(
β
h
-
β
-
hsoll
)
]
in a second control loop assigned to said rear axle, wherein β hsoll being a desired slideslip angle of said vehicle in a region of said rear axle, and β h being a slideslip angle of said vehicle in said region of said rear axle, and k 1 being a first controller gain;
wherein a desired value of a slip angle at said rear axle α hsoll being determined from an S h (α h ) characteristic representing a dependence of said lateral force S h on a slip angle α h at said rear axle;
wherein for said desired value S hsoll a value of a rear axle steering angle δ hsoll being determined by a relationship of a form
δ
hsoll
=
-
β
-
l
h
·
Ψ
.
v
x
+
α
hsoll
;
wherein said first steer-angle actuator is individually assigned to said front axle and said second steer-angle actuator is individually assigned to said rear axle;
wherein said first control loop assigned to said front axle and said second control loop assigned to said rear axle are decoupled from one another;
wherein a desired front axle value signal and a desired rear axle value signal are generated by a reference model, said reference model being implemented by an electronic computer from a processing of at least one output signal, representing a driver's wish, from a steering element position sensor, and of a sensor output signal characteristic of an operating state of said vehicle.