Method for controlling vehicle brake pressure as a function of the deviation of the actual slip of wheels relative to a desired slip

• US 5,556,176 A
• Filed: 05/30/1995
• Issued: 09/17/1996
• Est. Priority Date: 05/28/1994
• Status: Expired due to Fees

• Current Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Original Assignee: Mercedes-Benz AG (Mercedes-Benz Group AG)
• Inventors: Laubacher, Karl-Eugen, Steiner, Manfred, Bosch, Peter, Ammon, Dieter
• Primary Examiner(s): Butler, Douglas C.
• Application Number:
  US08/452,532
• Time in Patent Office: 476 Days
• Field of Search: 303/163, 303/165, 303/164, 303/174, 303/189, 303/140, 303/139, 303/143, 303/146, 303/147, 303/153, 303/167, 303/150, 180/197, 364/426.01, 364/426.02, 364/426.03, 188/181 A, 188/181 C, 188/181 R
• US Class Current: 303/165
• CPC Class Codes: B60T 2250/04 Vehicle reference speed; Vehicle body speed
• CPC Class Codes: B60T 2270/313 with less than three sensors (yaw rate, steering angle, lateral acceleration)
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• 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 invention relates to a method for controlling vehicle brake pressure as a function of the deviation of the actual slip of wheels relative to a prescribed desired slip. The desired slip is determined from the wheel speeds in such a way that the cornering forces occurring between wheel and roadway given the specific desired slip values and the adhesion conditions occurring, ensure stable handling.

Claims

1. Method for controlling brake pressure in a vehicle as a function of a deviation of actual slip of wheels of said vehicle relative to a desired slip, said method comprising the steps of:

detecting wheel speeds of the vehicle wheels;

determining vehicle speed based on detected wheel speeds;

determining actual slip for each wheel of said vehicle based on the wheel speeds and the vehicle speed;

determining a desired slip value for each wheel of said vehicle based on the vehicle speed and the detected wheel speed; and

generating a brake pressure gradient at brake cylinders at each of said wheels, which brake pressure gradient is a function of a difference between the actual slip and the desired slip for each of said wheels.

2. Method according to claim 1 further comprising:

determining a maximum possible desired slip for stable handling is determined; and

limiting said desired slip value for each wheel of said vehicle to said maximum possible desired slip.

3. Method according to claim 1 wherein only detected wheel speeds of the vehicle wheels and variables derived therefrom are used to determine the desired slip.

4. Method according to claim 1 wherein a vehicle deceleration determined from the measured wheel speeds is used to determine the desired slip.

5. Method according to claim 1 wherein said step of determining the desired slip comprises a further step of determining a turning curvature of a path of said vehicle.

6. Method according to claim 5 wherein the Ackerman condition is used to determine the turning curvature.

7. Method according to claim 1 wherein said step of determining a desired slip comprises determining a desired wheel slip for each wheel based on the desired slip determined from system deviation of the actual slip and desired slip, in at least one preceding control cycle for each wheel.

8. Method according to claim 7 wherein the desired wheel slip is determined as a function of variance of the system deviation for a number of directly preceding control cycles.

9. Method according to claim 7 wherein the ratio between the desired wheel slip and the desired slip is limited to a prescribed interval, in particular, to values between 0.8 and 1.2.

10. Method according to claim 1 wherein brake pressure control is performed only if a braking process is occurring and if a triggering criterion is fulfilled.

11. Method according to claim 10 wherein said triggering criterion comprise limiting values for wheel slip.

12. Method according to claim 1 wherein brake pressure control is performed independently for each of the wheels.

13. Method according to claim 1 wherein variables of state, being lateral acceleration, longitudinal acceleration and turning curvature are determined.

14. Method according claim 13 wherein the determined variables of state are transmitted to other control devices.