Method and system for controlling the braking force in a vehicle

• US 20040019422A1
• Filed: 08/25/2003
• Published: 01/29/2004
• Est. Priority Date: 05/10/2001
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Grob, Ferdinand, Arndt, Dietmar, Maier-Landgrebe, Rolf
• Granted Patent: US 6,801,862 B2
• Time in Patent Office: Days
• US Class Current: 701/70
• CPC Class Codes: B60T 8/17636 Microprocessor-based systems
• CPC Class Codes: B60T 8/58 responsive to speed and another condition or to plural speed conditions

Abstract

A method of controlling the braking force in a vehicle has the following steps: determining actual values of controlled variables; determining setpoint values of controlled variables; comparing the actual values with the setpoint values, thereby obtaining comparison results; and influencing wheel forces on the basis of the comparison results, wheel forces being used as controlled variables, the actual values of the wheel forces being determined by a sensor system which measures the wheel force, torques having a modulation frequency being generated at the wheels, whereby the slip of the wheels and the wheel force of the wheels are modifiable, the slip of the wheels and the wheel forces of the wheels are analyzed, and the setpoint values of the wheel forces are determined from the analysis of the slip of the wheels and the wheel forces of the wheels. A system for controlling the braking force in a vehicle is also described.

Claims

1. A method of controlling the braking force in a vehicle comprising the following steps:

determining actual values of controlled variables,

determining setpoint values of controlled variables,

comparing the actual values with the setpoint values, thereby obtaining comparison results, and

influencing wheel forces on the basis of the comparison results,

wherein

wheel forces are used as controlled variables,

the actual values of the wheel forces are determined by a sensor system (10) which measures the wheel force,

torques having a modulation frequency are generated at the wheels, thereby enabling the slip of the wheels (20) and the wheel force at the wheels (20) are modifiable,

the slip of the wheels (20) and the wheel forces of the wheels (20) are analyzed, and

the setpoint values of the wheel forces are determined from the analysis of the slip of the wheels (20) and from the wheel forces of the wheels (20).

2. The method as recited in claim 1,

wherein the longitudinal forces are determined by the sensor system (10) which measures the wheel force.

3. The method as recited in claim 1 or 2,

wherein the transverse forces are determined by the sensor system (10) which measures the wheel forces.

4. The method as recited in one of the preceding claims,

wherein the torques at the wheels (20) are hydraulically generated.

5. The method as recited in one of the preceding claims,

wherein the torques at the wheels (20) are generated by electric motors.

6. The method as recited in one of the preceding claims,

wherein the amplitude of the modulation frequency is considerably less than the torques that occur in normal driving operation.

7. The method as recited in one of the preceding claims,

wherein the wheel forces and the slip of the wheels (20) are analyzed in the specific frequency ranges of the known modulation frequency.

8. The method as recited in one of the preceding claims,

wherein the modulation frequency is in the range from 50 Hz to 100 Hz.

9. The method as recited in one of the preceding claims,

wherein

longitudinal wheel force characteristics of the wheels (20) are determined by analyzing the wheel forces and the slip of the wheels (20), and

the wheel forces at the maximum of the longitudinal wheel force characteristics are used as wheel force setpoint values.

10. The method as recited in one of the preceding claims,

wherein

transverse wheel force characteristics of the wheels are determined by analyzing the wheel forces and the slip of the wheels (20), and

a setpoint slip of the particular wheels at which the setpoint values of the particular transverse wheel forces occur is determined from the transverse wheel force characteristics.

11. The method as recited in one of the preceding claims,

wherein

a slip λ

₀ corresponding to zero longitudinal wheel force is determined by extrapolating the linearly increasing range of a longitudinal wheel force characteristic, and

the determined values of the wheel slip are corrected using slip λ

₀.

12. The method as recited in one of the preceding claims,

wherein the increase of a longitudinal wheel force characteristic is determined from the wheel slip modulation divided by the longitudinal wheel force modulation.

13. A system for controlling the braking force in a vehicle comprising:

means (10) for determining actual values of controlled variables,

means (12) for determining setpoint values of controlled variables,

means (14) for comparing the actual values with the setpoint values, thereby obtaining comparison results, and

means (16) for influencing wheel forces on the basis of the comparison results,

wherein

the controlled variables are wheel forces,

the means (10) for determining the actual values of the wheel forces are implemented as a sensor system (10) which measures the wheel force,

means (18) for modulating torques at the wheels are provided with a modulation frequency, thereby enabling the slip of the wheels (20) and the wheel force at the wheels (20) to be modified,

means (12) are provided for analyzing the slip of the wheels (20) and the wheel forces of the wheels (20), and

the means (12) for determining the setpoint values use the results of the analysis of the slip of the wheels (20) and the wheel forces of the wheels (20).

14. The system as recited in claim 13,

wherein the longitudinal forces are determinable by the sensor system (10) which measures the wheel force.

15. The system as recited in claim 13 or 14,

wherein the transverse forces are determinable by the sensor system (10) which measures the wheel force.

16. The system as recited in one of claims 13 through 15,

wherein the means (18) for modulating the torques at the wheels (20) are hydraulic means.

17. The system as recited in one of claims 13 through 16,

wherein the torques at the wheels (20) are electric motors.

18. The system as recited in one of claims 13 through 17,

wherein the amplitude of the modulation frequency is considerably less than the torques that occur in normal driving operation.

19. The system as recited in one of claims 13 through 18,

wherein the means (12) for analyzing the wheel forces and the slip of the wheels (20) operate in the specific frequency ranges of the known modulation frequency.

20. The system as recited in one of claims 13 through 19,

wherein the modulation frequency is in the range from 50 Hz to 100 Hz.

21. The system as recited in one of claims 13 through 20,

wherein

longitudinal wheel force characteristics of the wheels (20) are determinable by analyzing the wheel forces and the slip of the wheels (20), and

the wheel forces at the maximum of the longitudinal wheel force characteristics are used as wheel force setpoint values.

22. The system as recited in one of claims 13 through 21,

wherein

transverse wheel force characteristics of the wheels are determinable by analyzing the wheel forces and the slip of the wheels (20), and

a setpoint slip of the particular wheels at which the setpoint values of the particular transverse wheel forces occur is determined from the transverse wheel force characteristics.

23. The system as recited in one of claims 13 through 22,

wherein

a slip λ

₀ corresponding to zero longitudinal wheel force is determinable by extrapolating the linearly increasing range of a longitudinal wheel force characteristic, and

the determined values of the wheel slip are correctable using the slip λ

₀.

24. The system as recited in one of claims 13 through 23,

wherein the increase of a longitudinal wheel force characteristic is determinable from the wheel slip modulation divided by the longitudinal wheel force modulation.