Vehicle dynamic control system

• US 6,219,609 B1
• Filed: 10/19/1998
• Issued: 04/17/2001
• Est. Priority Date: 10/21/1997
• Status: Expired due to Term

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Konno, Toshihiro, Takahashi, Akira, Matsuno, Koji, Matsuura, Munenori, Mine, Atsushi
• Primary Examiner(s): Zanelli, Michael J.
• Application Number:
  US09/174,538
• Time in Patent Office: 911 Days
• Field of Search: 701/36, 701/72, 701/78, 701/83, 701/88, 701/69, 701/208, 701/213, 303/140, 303/146, 348/118, 348/119
• US Class Current: 701/72
• CPC Class Codes: B60T 2201/14 Electronic locking-differential
• CPC Class Codes: B60T 2201/16 Curve braking control, e.g. turn control within ABS control algorithm
• CPC Class Codes: B60T 2210/24 Curve radius
• CPC Class Codes: B60T 2210/36 Global Positioning System [GPS]
• 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

Abstract

The present invention provides a vehicle dynamic control system which alters characteristics of respective vehicle movement controllers so that they can function properly against coming and foreseeable running conditions and current running conditions, recognizing beforehand details of an emerging curve on the road to be traveled. The system comprises a vehicle movement control alterant and at least one among vehicle movement controllers, i.e., a brake controller, a left/right wheel differential limiter controller and power distribution controller. When the vehicle is approaching the curve, the vehicle movement control alterant alters characteristics of a braking controller, the left/right wheel differential limiter controller and the power distribution controller to those favorable to turning for driving through a curve appropriately. When the vehicle is approaching the curve end, the alternate alters characteristics of the left/right differential controller to those favorable to stabilizing running so that the vehicle can pass the curve end and go into straight road appropriately.

Claims

1. A dynamic control system for a vehicle, comprising:

a navigation means comprising a vehicle position detector, an auxiliary memory and a processing unit for outputting a positional signal;

a curve geometry calculating means responsive to said positional signal for outputting a curve informational signal;

a vehicle dynamic control means responsive to said curve informational signal for controlling the vehicle turning movement and producing a dynamic control signal to improve the vehicle running stability to a posture that is favorable to turning along an emerging curve in accord with the calculated curve geometry; and

a characteristic changing means responsive to the dynamic control signal for changing a controlling characteristic of the vehicle dynamic control means to favor turning along the emerging curve when the vehicle is within a predetermined distance from the curve.

2. The dynamic control system according to claim 1, wherein the characteristic changing means includes a means for increasing sensitivity to steering responsiveness of the dynamic control means.

3. The dynamic control system according to claim 2, wherein the vehicle dynamic control means includes a brake controlling means for calculating a braking force to be applied to a wheel selected on which to apply said braking force in order to correct a steering deviation of the vehicle based on a yaw rate applied to the vehicle,

said brake controlling means includes:

an actual yaw rate detecting means for detecting an actual yaw rate;

a target yaw rate calculating means for calculating a target yaw rate based on said vehicle running condition including a vehicle speed and, steering angle;

a yaw rate deviation calculating means for calculating a yaw rate deviation of said actual yaw rate and said target yaw rate;

a yaw rate deviation correcting means for calculating corrected yaw rate deviation by correcting said yaw rate deviation based on a vehicle side slip angle;

a target braking force calculating means for calculating target braking force based on the actual yaw rate and the yaw rate deviation; and

a braking wheel determining means for determining a braking wheel by the sign of the deviation of the yaw rate deviation from a threshold value,

said changing means narrows an insensitivity band of the vehicle side slip for correcting the yaw rate deviation.

4. The dynamic control system according to claim 1, wherein the vehicle dynamic control means includes a brake controlling means for calculating a braking force to be applied to a wheel selected on which to apply said braking force in order to correct a steering deviation of the vehicle based on a yaw rate applied to the vehicle.

5. The dynamic control system according to claim 1, wherein the vehicle dynamic control means includes a brake controlling means for calculating a braking force to be applied to a wheel selected on which to apply said braking force in order to correct a steering deviation of the vehicle based on a yaw rate applied to the vehicle,

said brake controlling means includes:

an actual yaw rate detecting means for detecting an actual yaw rate;

a target yaw rate calculating means for calculating a target yaw rate;

a yaw rate deviation calculating means for calculating a yaw rate deviation of the actual yaw rate from the target yaw rate;

a target braking force calculating means for calculating target braking force based on the actual yaw rate and the yaw rate deviation; and

a braking wheel determining means for determining a wheel on which to apply braking force based upon the yaw rate deviation and a threshold value,

wherein the characteristic changing means narrows the yaw rate deviation from the threshold value.

6. The dynamic control system according to claim 5, wherein the vehicle dynamic characteristic changing means includes means for reducing the differential limiting force of the wheel differential controlling means so as to improve turning performance.

7. The dynamic control system according to claim 1, wherein the vehicle dynamic control means includes wheel differential controlling means for controlling the differential limiting force between a left and right wheel.

8. The dynamic control system according to claim 7, wherein the vehicle dynamic characteristic changing means includes means for reducing the differential limiting force of the power distributing means so as to improve turning performance.

9. The dynamic control system according to claim 1, wherein the vehicle dynamic control means includes a power distributing means for controlling the differential limiting force between front and rear wheels to distribute the driving force to the front and rear wheels.

10. The dynamic control system according to claim 1, wherein the curve geometry calculating means includes a road width detector for detecting a road width based on a stereo-image outside of said vehicle, and corrects for the road geometry detected by the navigation means for the road width so as to obtain a more accurate current position of the vehicle.

11. The dynamic control system according to claim 1, wherein the characteristic changing means changes the controlling characteristic of the dynamic control means to favorably stabilize the vehicle attitude when the vehicle exits the curve for transition from curved road to straight road.

12. A method of using a dynamic control system of a vehicle having a dynamic control device, comprising:

detecting running conditions of the vehicle;

detecting a current position of the vehicle and a curve;

calculating a first distance between the curve and the current position; and

changing a controlling characteristic of the dynamic control device to favorably enter the curve when the first distance is less than a predetermined distance.

13. The method according to claim 12, further comprising:

calculating a second distance between the curve end and the current position; and

changing a controlling characteristic of the dynamic control device to favorably stabilize a vehicle'"'"'s attitude to transition from a curved road to a straight road when the second distance is less than a predetermined distance.

14. The method according to claim 12, wherein the changed control characteristic is accomplished by increasing sensitivity to the steering responsiveness of the dynamic control means based on the running conditions.

15. The method according to claim 12, wherein the changed control characteristic is accomplished by reducing a differential limit force of the dynamic control means.