Method and device for controlling vehicle motion and vehicle equipped with same

• US 10,384,673 B2
• Filed: 07/27/2015
• Issued: 08/20/2019
• Est. Priority Date: 09/29/2014
• Status: Active Grant

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi Automotive Systems Limited (Hitachi, Ltd.)
• Inventors: Yamakado, Makoto, Innami, Toshiyuki, Nagatsuka, Keiichiro
• Primary Examiner(s): Brushaber, Frederick M
• Application Number:
  US15/510,110
• Publication Number:
  US 20170305416A1
• Time in Patent Office: 1,485 Days
• CPC Class Codes: B60T 2201/16 Curve braking control, e.g. turn control within ABS control algorithm
• CPC Class Codes: B60T 2270/303 Stability control with active acceleration
• CPC Class Codes: B60T 2270/608 Electronic brake distribution (EBV/EBD) features related thereto
• CPC Class Codes: B60T 7/12 for automatic initiation; for initiation not subject to will of driver or passenger limiting speed of vehicles other than rail vehicles B60K31/00
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60T 8/1766 Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle
• CPC Class Codes: B60T 8/24 responsive to vehicle inclination or change of direction, e.g. negotiating bends using electrical circuitry or regulation means B60T8/17
• CPC Class Codes: B60W 10/16 Axle differentials, e.g. for dividing torque between left and right wheels
• CPC Class Codes: B60W 10/192 electric brakes
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 2720/406 between left and right wheel
• CPC Class Codes: B60W 30/045 Improving turning performance
• CPC Class Codes: B60W 30/18109 Braking
• CPC Class Codes: B60W 40/109 Lateral acceleration
• CPC Class Codes: B60W 40/114 Yaw movement

Abstract

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.

Claims

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

5. The vehicle control method according to claim 4, wherein the front wheel distribution ratio R_FR is generated by

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

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

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

20. The vehicle controller according to claim 19, wherein the front/rear wheel distribution ration R_FR is generated by

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

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

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.