Method for operating a brake device of a vehicle with a brake pressure difference on an axle adapted as a function of a steer input

Patent metadata

Field	Value
Publication number	US-9340187-B2
Application number	US-201113636640-A
Country	US
Kind code	B2
Filing date	Mar 23, 2011
Priority date	Mar 24, 2010
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

A method, and related device, for operating a brake device of a vehicle with brake slip regulation (ABS) on roadways with different friction coefficients on different sides, as a result of which a braking yaw moment is imparted to the vehicle during braking, characterized in that, on at least one axle of the vehicle, an absolute brake pressure difference between the brake pressure at the wheel with the higher friction coefficient and the brake pressure at the wheel with the lower friction coefficient is adapted as a function of a steer input, intended to produce a yaw moment acting counter to the braking yaw moment, by the driver and/or by an automatically intervening auxiliary steering system.

First claim

The invention claimed is:

1. A method for operating a brake device of a vehicle with brake slip regulation (ABS) on roadways with different friction coefficients on different sides, as a result of which a braking yaw moment is imparted to the vehicle during braking, the method comprising:
adapting, on at least one axle of the vehicle, an absolute brake pressure difference between the brake pressure at the wheel with the higher friction coefficient and the brake pressure at the wheel with the lower friction coefficient as a function of a steer input, to produce a yaw moment acting counter to the braking yaw moment, which is caused by at least one of the driver and an automatically intervening auxiliary steering system;
wherein there is a modification of an absolute value of the absolute brake pressure difference between the wheel with the higher friction coefficient and the wheel with the lower friction coefficient,
wherein the modification occurs as a function of a steering input, intended to produce a yaw moment acting counter to a braking yaw moment, by at least one of a driver and an automatically intervening auxiliary steering system,
wherein the actual yaw rate of the vehicle is adjusted by closed-loop control to a setpoint yaw rate as a function of the steering input by the at least one of the driver and the auxiliary steering system by modifying the absolute value of the brake pressure difference or the differential brake pressure value, wherein the brake pressure difference represents a manipulated variable of the closed-loop control system, so that by the closed-loop control, stability of the vehicle is given priority, and the absolute value of the brake pressure difference at the axle is adapted on a continuous basis so as to minimize a system deviation, and
wherein there is an incorrect steering input in the presence of a braking yaw moment, so that the actual yaw rate increases so as to reduce driving stability, the differential brake pressure value is reduced to avoid further increasing the instability or to reduce the braking yaw moment through a reduced asymmetry of the braking forces.

2. The method of claim 1 , wherein the brake pressure difference permitted is larger, the larger the counter yaw moment produced by the steer input, and in that the brake pressure difference permitted is smaller, the smaller the counter yaw moment produced by the steer input.

3. The method of claim 2 , wherein the adaptation of the brake pressure difference is performed exclusively as a function of the steer input by the driver.

4. The method of claim 2 , wherein the adaptation of the brake pressure difference is performed continuously as a function of the steer input.

5. The method of claim 2 , wherein the adaptation of the brake pressure difference is performed on a front axle brake device.

6. The method of claim 2 , wherein the actual yaw rate of the vehicle is adjusted to a setpoint yaw rate as a function of the steer input by modifying the brake pressure difference.

7. The method of claim 6 , wherein the setpoint yaw rate is substantially equal to zero.

8. The method of claim 1 , wherein the yaw rate represents a controlled variable and the steering input represents a disturbance.

9. A device for operating a brake device of a vehicle with brake slip regulation (ABS) on roadways with different friction coefficients on different sides, as a result of which a braking yaw moment is imparted to the vehicle during braking, comprising:
at least one brake actuator per wheel of the axle, the brake actuator being controllable electrically, directly or indirectly, and being actuated by pressure medium;
at least one brake pressure sensor per brake actuator for producing sensor signals dependent on the brake pressure acting in the respective brake actuator;
at least one steering angle sensor for producing sensor signals dependent on the steer input;
at least one yaw rate sensor for producing sensor signals dependent on the yaw rate of the vehicle or on yaw rates acting on the vehicle; and
an electronic control unit configured to adapt the brake pressure difference between the brake pressure at the wheel with the higher friction coefficient and the brake pressure at the wheel with the lower friction coefficient as a function of the sensor signals produced by the steering angle sensor, the yaw rate sensor and the brake pressure sensors;
wherein there is a modification of an absolute value of the absolute brake pressure difference between the wheel with the higher friction coefficient and the wheel with the lower friction coefficient,
wherein the modification occurs as a function of a steering input, intended to produce a yaw moment acting counter to a braking yaw moment, by at least one of a driver and an automatically intervening auxiliary steering system, and
wherein the actual yaw rate of the vehicle is adjusted by closed-loop control to a setpoint yaw rate as a function of the steering input by the at least one of the driver and the auxiliary steering system by modifying the absolute value of the brake pressure difference or the differential brake pressure value, wherein the brake pressure difference represents a manipulated variable of the closed-loop control system, so that by the closed-loop control, stability of the vehicle is given priority, and the absolute value of the brake pressure difference at the axle is adapted on a continuous basis so as to minimize a system deviation, and
wherein there is an incorrect steering input in the presence of a braking yaw moment, so that the actual yaw rate increases so as to reduce driving stability, the differential brake pressure value is reduced to avoid further increasing the instability or to reduce the braking yaw moment through a reduced asymmetry of the braking forces.

10. The device of claim 9 , further comprising:
an auxiliary steering system controlled by the control unit so that a yaw moment acting counter to the braking yaw moment is produced at the steering wheel, adjusting the difference between the actual yaw rate and the setpoint yaw rate to zero.

11. The device of claim 9 , wherein the brake pressure difference permitted is larger, the larger the counter yaw moment produced by the steer input, and in that the brake pressure difference permitted is smaller, the smaller the counter yaw moment produced by the steer input.

12. The device of claim 9 , wherein the adaptation of the brake pressure difference is performed exclusively as a function of the steer input by the driver.

13. The device of claim 9 , wherein the adaptation of the brake pressure difference is performed continuously as a function of the steering input.

14. The device of claim 9 , wherein the adaptation of the brake pressure difference is performed on a front axle brake device.

15. The device of claim 9 , wherein the actual yaw rate of the vehicle is adjusted to a setpoint yaw rate as a function of the steer input by modifying the brake pressure difference.

16. The device of claim 15 , wherein the setpoint yaw rate is substantially equal to zero.

17. The device of claim 9 , wherein the yaw rate represents a controlled variable and the steering input represents a disturbance.

Assignees

• Hecker Falk
• Schmidt Marco
• Knorr Bremse Systeme Fuer Nutzfahrzeuge Gmbh

Inventors

• Hecker Falk
• Schmidt Marco

Classifications

• B60T2220/03

  Driver counter-steering; Avoidance of conflicts with ESP control · CPC title

• B60T8/505

  Pressure reapplication in a mu-split situation, i.e. a situation with different coefficients of friction on both sides of the vehicle · CPC title

• B60T8/1755

  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 title

• B60T8/1764 Primary

  Regulation during travel on surface with different coefficients of friction, e.g. between left and right sides, mu-split {or between front and rear} · CPC title

• B60T2260/024

  Yawing moment compensation during mu-split braking · CPC title