Method for determining a wheel brake pressure

• US 5,732,378 A
• Filed: 06/07/1995
• Issued: 03/24/1998
• Est. Priority Date: 11/25/1994
• Status: Expired due to Fees

• Current Assignee: ITT Automotive Europe GmbH (Xylem, Inc.)
• Original Assignee: ITT Automotive Europe GmbH (Xylem, Inc.)
• Inventors: Nederkoorn, C. Jan S., Eckert, Alfred
• Primary Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US08/476,305
• Time in Patent Office: 1,021 Days
• Field of Search: 364/426.01, 364/426.02, 364/426.03, 364/426.015, 364/426.023, 364/426.027, 364/426.028, 364/426.037, 303/139, 303/140, 303/146, 303/147, 303/148, 303/150, 303/155, 303/167, 303/186, 303/189, 180/197
• US Class Current: 701/83
• CPC Class Codes: B60G 2400/1042 using at least two sensors
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• CPC Class Codes: B60T 2270/313 with less than three sensors (yaw rate, steering angle, lateral acceleration)
• 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: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 2422/95 Measuring the same parameter at multiple locations of the vehicle
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 2520/20 Sideslip angle
• CPC Class Codes: B60W 2720/14 Yaw
• CPC Class Codes: B60W 2720/30 Wheel torque
• CPC Class Codes: B60W 30/02 Control of vehicle driving stability
• CPC Class Codes: B60W 40/064 Degree of grip

Abstract

A method for controlling the brakes in an automotive vehicle. The vehicle has a velocity and a plurality of wheels, each wheel having an angular velocity and a brake which is operable by applying a pressure agent to the brake. An amount of the pressure agent to be applied to, or released from, each brake, individually, to implement a desired braking operation is determined. Switching times corresponding to the amounts of the pressure agent are calculated for opening and closing the inlet valve or outlet valve of each respective brake, individually. An estimated vehicle velocity and an estimated wheel angular velocity which result from applying the pressure agent to the brakes are determined. The actual velocity of the vehicle and the actual angular velocity of the wheels are determined by measuring the angular velocity, and determining the velocity based on the measurement. A comparison is performed, either between (1) the actual velocity and the estimated vehicle velocity, or (2) the actual angular velocity and the estimated wheel angular velocity. The amounts of the pressure agent to be applied to, or released from, each respective brake are adjusted, based on the comparison.

Claims

1. In an automotive vehicle having a velocity and a plurality of wheels, each wheel having an angular velocity and a brake which is operable by applying a pressure agent to the brake, a method for controlling the brakes, comprising the steps of:

(a) determining amounts of the pressure agent to be applied to, or released from, each respective brake, individually, to implement a desired braking operation;

(b) calculating an estimated vehicle velocity and an estimated wheel angular velocity which result from applying the respective amounts of the pressure agent to the brakes; and

(c) determining the velocity of the vehicle and the angular velocity of the wheels by measuring at least one of the velocity and the angular velocity, and determining the other one of the velocity and the angular velocity based on the measurement;

(d) performing a comparison between;

(1) the velocity determined in step (c) and the estimated vehicle velocity, or

(2) the angular velocity determined in step (c) and the estimated wheel angular velocity, respectively; and

(e) adjusting the amounts of the pressure agent to be applied to, or released from, each respective brake, based on the comparison.

2. A method according to claim 1, wherein each brake has an inlet valve and an outlet valve, and steps (a) and (e) include determining switching times for opening and closing the inlet valve or outlet valve of each respective brake, individually.

3. A method according to claim 2, wherein a pressure change occurs in one of the brakes when the pressure agent is applied to or released from the brake, further comprising the step of:

calculating said pressure change as a quadratic function of a length of time that the inlet valve or outlet valve of the one brake is opened.

4. A method according to claim 1, further comprising calculating a braking torque applied by each one of the brakes to the respective wheel to which the one brake corresponds, based on the amounts of the pressure agent to be applied to, or released from, each respective brake and at least one brake-specific attribute of each respective brake.

5. A method according to claim 4, further comprising calculating a respective wheel slip value for each one of the wheels, individually, based on the braking torque applied to the brake of the one wheel.

6. A method according to claim 1, wherein step (b) includes calculating the estimated vehicle velocity based on a dynamic axle load distribution of the vehicle.

7. In a motor vehicle, which is provided with means for determining the angular velocity of the wheels of the vehicle, means for determining the velocity of the vehicle, and means for determining the volume of the pressure medium taken up or released by the wheel brakes, a method for determining correction variables used in controlling the wheel brakes of the vehicle, comprising the steps of:

calculating the angular velocity of the wheels and the velocity of the vehicle in an evaluation unit, based on the amount of pressure agent taken up or released by the wheel brakes, and

comparing the calculated angular velocity of the wheels and calculated velocity of the vehicle with corresponding values of the angular velocity of the wheels and velocity of the vehicle determined by the angular velocity determining means and vehicle velocity determining means, respectively, and determining correction variables based on the comparison.

8. Method in accordance with claim 7, further comprising:

determining switching times of inlet and outlet valves of said wheel brakes, and

determining the amount of pressure medium taken up or released from the switching times by a quadratic comparison.

9. Method in accordance with claim 8, further comprising:

determining a braking torque from the pressure medium volume taken up or released by the wheel brakes,

taking wheel brake-specific values into account, and

calculating the slip of the wheels from the braking torque.

10. Method in accordance with claim 8, further comprising:

determining correction variables based on the comparing, and

using the correction variables to correct the pressure determined on the basis of the switching times of the inlet and outlet values.

11. Method in accordance with claim 7, further comprising using the dynamic axle load distribution for calculating the angular velocity of the wheels and velocity of the vehicle.

12. In a motor vehicle having a plurality of wheel brakes, each brake having inlet and outlet valves for transmitting a pressure agent to and from the brakes, respectively, said vehicle having means for determining the angular velocity of the wheels of the vehicle, means for determining the velocity of the vehicle, and means for determining the volume of the pressure medium taken up or released by the wheel brakes, a method for controlling the value opening and closing times in the wheel brakes of the vehicle, comprising the steps of:

determining opening and closing times for the inlet and outlet valves to apply the pressure agent to, or release the pressure agent from, each respective brake, individually, to implement a desired braking operation;

calculating the angular velocity of the wheels and the velocity of the vehicle in an evaluation unit, based on the opening and closing times for the inlet and outlet valves of the wheel brakes;

comparing the calculated angular velocity of the wheels and calculated velocity of the vehicle with corresponding values of the angular velocity of the wheels and velocity of the vehicle determined by the angular velocity determining means and vehicle velocity determining means, respectively;

determining correction variables based on the comparison; and

adjusting the valve opening and closing times, based on the correction variables.