Method and device for controlling vehicle motion and vehicle equipped with same
The purpose of the present invention is to provide a device and method for controlling vehicle motion and a vehicle equipped with the device, such that driving force and/or braking force is properly distributed between front wheels and rear wheels so that steering characteristics are made suitable and controllability and stability improve. This device comprises a means for controlling braking and/or driving force distribution between the front wheels and rear wheels of a vehicle such that when the absolute value of lateral acceleration of the vehicle increases, the distribution to the front wheels is made smaller, and when the absolute value of lateral acceleration of the vehicle decreases, the distribution to the front wheels is made larger.
1. A vehicle control method for controlling a driving force or a braking force in a longitudinal direction of a vehicle based on an input value related to a lateral motion of the vehicle, the method comprising:
changing a front/rear wheel distribution ratio for the driving force or the braking force based on the input value, wherein
a combined acceleration that includes a longitudinal acceleration and a lateral acceleration of the vehicle is directed to make a curved transition with an elapsed time,
at least one control of a first control and a second control is effected, wherein
the first control controls a front wheel distribution ratio of the front/rear distribution ratio to be smaller than the front wheel distribution ratio in a case when the input value is zero, when the input value increases, and
the second control controls the front wheel distribution ratio to be larger than the front wheel distribution ratio in a case when the input value is zero, when the input value decreases.
2. The vehicle control method according to claim 1 , wherein the first control and the second control are effected.
3. The vehicle control method according to claim 2 , wherein the input value is an absolute value of a lateral acceleration of the vehicle.
4. The vehicle control method according to claim 3 , wherein the front wheel distribution ratio R FR is generated by
R
FR
=
R
FR
0
-
sgn
(
G
y
·
G
.
y
)
C
dp
1
+
Ts
G
.
y
wherein Gy is a lateral acceleration of the vehicle, Gy_dot is a lateral jerk of the vehicle, Cdp is a lateral jerk gain, T is a first-order delay time constant, s is a Laplace operator, and R FR0 is an initial distribution ratio.
5. The vehicle control method according to claim 4 , wherein the front wheel distribution ratio R FR is generated by
R
FR
=
R
FR
0
-
sgn
(
r
·
r
.
)
C
dpr
1
+
T
r
s
r
.
wherein r is a vehicle yaw rate, r_dot is a vehicle yaw angular acceleration, Cdpr is a yaw angular acceleration gain, T is a first-order delay time constant, s is a Laplace operator, and R FR0 is an initial distribution ratio.
6. The vehicle control method according to claim 2 , wherein the input value is an absolute value of a yaw rate of the vehicle.
7. The vehicle control method according to claim 2 , wherein the input value is an absolute value of a steering angle.
8. The vehicle control method according to claim 7 , wherein the front wheel distribution ratio R FR is generated by
R
FR
=
R
FR
0
-
sgn
(
δ
·
δ
.
)
C
dp
δ
1
+
T
r
s
δ
.
wherein
δ is a steering angle, δ_dot is a steering angular velocity, Cdpδ is a steering angular velocity gain, T is a first-order delay time constant, s is a Laplace operator, and R FR0 is an initial distribution ratio.
9. The vehicle control method according to claim 2 , wherein the front wheel distribution ratio is controlled using a map in which values of the front wheel distribution ratio corresponding to the input value are stored in advance.
10. The vehicle control method according to claim 2 , wherein the front wheel distribution ratio of the braking force is reduced to decrease the braking force and/or the braking torque generated by the front wheels,
the front wheel distribution ratio of the braking force is increased to increase the braking force and/or the braking torque generated by the front wheels,
the front wheel distribution ratio of the driving force is reduced to decrease the driving force and/or driving torque generated by the front wheels, and
the front wheel distribution ratio of the driving force is increased to increase the driving force and/or driving torque generated by the front wheels.
11. The vehicle control system according to claim 10 , further comprising a stereo camera, wherein the control device is enclosed in the stereo camera.
12. The vehicle control method according to claim 1 , wherein the vehicle is controlled to decelerate when the input value increases, and the vehicle is controlled to accelerate when the input value decreases.
13. The vehicle control method according to claim 12 , wherein the acceleration and deceleration control of the vehicle is performed based on a longitudinal acceleration command value, and
the longitudinal acceleration command value Gxc is generated by
G
xc
=
-
sgn
(
G
y
·
G
.
y
)
C
xy
1
+
Ts
G
.
y
wherein Gy is a lateral acceleration of the vehicle, Gy_dot is a lateral jerk of the vehicle, Cxy is a lateral jerk gain, T is a first-order delay time constant, and s is a Laplace operator.
14. The vehicle control method according to claim 12 , wherein, in a vehicle fixed coordinate system in which a longitudinal acceleration of the vehicle is set as an x-axis, a lateral acceleration of the vehicle is set as a y-axis, a forward direction of the vehicle is set as positive x-axis, and a steering direction of the vehicle is set as a positive y-axis, when the steering is input to the vehicle or when the vehicle starts to turn in the positive y-direction, the lateral acceleration of the vehicle is generated in the positive direction and the longitudinal acceleration of the vehicle is generated in the negative direction, so that a trajectory of coordinates displaying the longitudinal acceleration and the lateral acceleration is a smooth curve in a clockwise direction from the vicinity of the origin to a II quadrant.
15. A vehicle control system which comprises:
a front motor configured to drive front wheels, a rear motor configured to drive rear wheels, and a control device configured to execute a vehicle control method for controlling a driving force or a braking force in a longitudinal direction of a vehicle based on an input value related to a lateral motion of the vehicle, the method comprising:
changing a front/rear wheel distribution ratio for the driving force or the braking force based on the input value, wherein
a combined acceleration that includes a longitudinal acceleration and a lateral acceleration of the vehicle is directed to make a curved transition with an elapsed time,
at least one control of a first control and a second control is effected, wherein
the first control controls a front/rear wheel distribution ratio of the front/rear distribution ratio to be smaller than the front/rear wheel distribution ratio in a case when the input value is zero, when the input value increases, and
the second control controls the front/rear wheel distribution ratio to be larger than the front/rear wheel distribution ratio in a case when the input value is zero, when the input value decreases, wherein the control device is configured to vary the distribution ratio of the front wheels by controlling a supply voltage to the front motor.
16. A vehicle controller for a vehicle for controlling a driving force or a braking force in a longitudinal direction of a vehicle based on an input value related to a lateral motion of the vehicle, the controller comprising:
a processor configured to change a front/rear distribution ratio among the driving force or the braking force based on the input value, and conduct at least one control of following 1st control and following 2nd control,
wherein a combined acceleration of a longitudinal acceleration and lateral acceleration of the vehicle is directed to make a curved transition with an elapse of time,
wherein the first control controls a front wheel distribution ratio of the front/rear distribution ratio to be smaller than the front wheel distribution ratio in a case when the input value is zero, when the input value increases, and
wherein the second control controls the front wheel distribution ratio to be larger than the front wheel distribution ratio in a case when the input value is zero, when the input value decreases.
17. The vehicle controller according to claim 16 , wherein the processor conducts the first control and the second control.
18. The vehicle controller according to claim 17 , wherein the input value is an absolute value of a lateral acceleration of the vehicle.
19. The vehicle controller according to claim 18 , wherein the front/rear wheel distribution ratio RFR is generated by
R
FR
=
R
FR
0
-
sgn
(
G
y
·
G
.
y
)
C
dp
1
+
Ts
G
.
y
wherein Gy is a lateral acceleration of the vehicle, Gy_dot is a lateral jerk of the vehicle, Cdp is a lateral jerk gain, T is a first-order delay time constant, s is a Laplace operator, and RFR0 is an initial distribution ratio.
20. The vehicle controller according to claim 19 , wherein the front/rear wheel distribution ration R FR is generated by
R
FR
=
R
FR
0
-
sgn
(
r
·
r
.
)
C
dpr
1
+
T
r
s
r
.
wherein r is a vehicle yaw rate, r_dot is a vehicle yaw angular acceleration, Cdpr is a yaw angular acceleration gain, T is a first-order delay time constant, s is a Laplace operator, and RFR0 is an initial distribution ratio.
21. The vehicle controller according to claim 17 , wherein the input value is an absolute value of a yaw rate of the vehicle.
22. The vehicle controller according to claim 17 , wherein the input value is an absolute value of a steering angle.
23. The vehicle controller according to claim 22 , the front/rear wheel distribution ratio RFR is generated by
R
FR
=
R
FR
0
-
sgn
(
δ
·
δ
.
)
C
dp
δ
1
+
T
r
s
δ
.
wherein δ is a steering angle, δ_dot is a steering angular velocity, Cdpδ is a steering angular velocity gain, T is a first-order delay time constant, s is a Laplace operator, and RFR0 is an initial distribution ratio.
24. The vehicle controller according to claim 17 , wherein the front/rear wheel distribution ratio is controlled using a map in which values of the front/rear wheel distribution ratio corresponding to the input value are stored in advance.
25. The vehicle controller according to claim 17 , wherein the front/rear wheel distribution ratio of the braking force is reduced to decrease the braking force and/or the braking torque generated by the front wheels, the front/rear wheel distribution ratio of the braking force is increased to increase the braking force and/or the braking torque generated by the front wheels, the front/rear wheel distribution ratio of the driving force is reduced to decrease the driving force and/or driving torque generated by the front wheels, and the front/rear wheel distribution ratio of the driving force is increased.
26. The vehicle controller according to claim 16 , wherein the vehicle is controlled to decelerate when the input value increases, and the vehicle is controlled to accelerate when the input value decreases.
27. The vehicle controller according to claim 26 , wherein the acceleration and deceleration control of the vehicle is performed based on a longitudinal acceleration command value, and the longitudinal acceleration command value Gxc is generated by
G
xc
=
-
sgn
(
G
y
·
G
.
y
)
C
xy
1
+
Ts
G
.
y
wherein Gy is a lateral acceleration of the vehicle, Gy_dot is a lateral jerk of the vehicle, Cxy is a lateral jerk gain, T is a first-order delay time constant, and s is a Laplace operator.
28. The vehicle controller according to claim 26 , wherein, in a vehicle fixed coordinate system in which a longitudinal acceleration of the vehicle is set as an x-axis, a lateral acceleration of the vehicle is set as a y-axis, a forward direction of the vehicle is set as positive x-axis, and a steering direction of the vehicle is set as a positive y-axis, when the steering is input to the vehicle or when the vehicle starts to turn in the positive y-direction, the lateral acceleration of the vehicle is generated in the positive direction and the longitudinal acceleration of the vehicle is generated in the negative direction, so that a trajectory of coordinates displaying the longitudinal acceleration and the lateral acceleration is a smooth curve in a clockwise direction from the vicinity of the origin to a II quadrant.