Brake control system

• US 6,212,460 B1
• Filed: 07/29/1999
• Issued: 04/03/2001
• Est. Priority Date: 09/06/1996
• Status: Expired due to Term

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated), GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated), General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Pastor, Stephen R, Rizzo, Michael D, Carson, Douglass L, Bassett, Duane E, Tierney, Gordon L, Paul, Ronald
• Primary Examiner(s): Louis-Jacques, Jacques H.
• Application Number:
  US09/230,824
• Time in Patent Office: 614 Days
• Field of Search: 701/70, 701/71, 701/72, 701/74, 701/78, 701/83, 701/88, 701/89, 701/79, 701/76, 303/122.08, 303/140, 303/147, 303/115.2, 303/113.2, 303/162, 303/146, 303/148, 303/191, 303/112, 303/139, 180/197, 180/412, 180/442, 180/445, 180/422, 180/428, 180/244, 188/156, 188/158, 188/181 T
• US Class Current: 701/70
• CPC Class Codes: B60L 2240/16 longitudinal
• CPC Class Codes: B60L 2240/18 lateral
• CPC Class Codes: B60L 2240/22 Yaw angle
• CPC Class Codes: B60L 2240/24 Steering angle
• CPC Class Codes: B60L 2240/461 Speed
• CPC Class Codes: B60L 2240/463 Torque
• CPC Class Codes: B60L 2240/465 Slip
• CPC Class Codes: B60L 3/0076 relating to braking
• CPC Class Codes: B60L 3/108 whilst braking, i.e. ABS
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60T 2210/22 Banked curves
• 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

In a vehicle with an active brake control system a control method comprising to the steps of: determining individual wheel speeds of the vehicle wheels responsive to sensor output signals (1016, 1018); determining a vehicle reference velocity responsive to the individual wheel speeds (1002-1012); measuring vehicle yaw rate (1128); determining a delta velocity for each wheel responsive to the individual wheel speed for the wheel and the vehicle reference velocity (326); and when the active brake control system is in the active state for at least one of the wheels, (a) setting a base delta velocity for the one wheel equal to the delta velocity for the one wheel immediately prior to the active brake control obtaining the active state for the one wheel (200); (b) determining a control term responsive to the measured vehicle yaw rate (806), wherein the control term represents a desired delta velocity for the one wheel; (c) setting a first target change in delta velocity responsive to the base delta velocity and the control term (204); and (d) controlling a first wheel brake for the one wheel so that a difference between the delta velocity for the one wheel and the desired delta velocity for the one wheel is minimized (208).

Claims

1. In a vehicle with an active brake control system (52, 54, 56, 58, 68) and a plurality of vehicle wheels (12, 14, 16, 18), wherein the active brake control system has an active state and an inactive state for each wheel, a control method comprising the steps of:

determining individual wheel speeds of the vehicle wheels responsive to sensor output signals (1016, 1018);

determining a vehicle reference velocity responsive to the individual wheel speeds (1002-1012);

measuring vehicle yaw rate (1128);

determining a delta velocity for each wheel responsive to the individual wheel speed for the wheel and the vehicle reference velocity (326); and

when the active brake control system is in the active state for at least one of the wheels,

(a) setting a base delta velocity for the at least one of the wheels equal to the delta velocity for the at least one of the wheels immediately prior to the active brake control obtaining the active state for the at least one of the wheels (200);

(b) determining a control term responsive to the measured vehicle yaw rate (806), wherein the control term represents a desired delta velocity for the at least one of the wheels;

(c) setting a first target change in delta velocity responsive to the base delta velocity and the control term (204), wherein the first target change in delta velocity represents an amount of change desired in the delta velocity for the at least one of the wheels; and

(d) controlling a first wheel brake for the at least one of the wheels so that a difference between the delta velocity for the at least one of the wheels and the desired delta velocity for the at least one of the wheels is minimized (208).

2. A control method according to claim 1, wherein the step of determining the vehicle reference velocity comprises the sub-steps of:

determining a velocity compensation term responsive to the measured vehicle yaw rate (1002); and

determining the vehicle reference velocity responsive to the sensor output signals and the compensation term (1004, 1006), wherein an effect of vehicle yaw rate on the vehicle reference velocity is compensated for.

3. A control method according to claim 2, wherein the individual wheel speeds are determined responsive to the sensor output signals and the compensation term (1016, 1018), wherein an effect of vehicle yaw rate on the individual wheel speeds is compensated for.

4. A control method according to claim 1, also comprising the step of determining a desired vehicle yaw rate (454) responsive to a plurality of vehicle conditions.

5. A control method according to claim 4, wherein the control term is also determined responsive to the desired vehicle yaw rate.

6. A control method according to claim 1, also comprising the step of:

measuring a brake fluid pressure in a master cylinder (94), wherein the first target change in delta velocity is also responsive to the measured brake fluid pressure.

7. A control method according to claim 6, also comprising the steps of:

determining a second target change in delta velocity responsive to the measured brake fluid pressure (374);

controlling a second wheel brake for another of the wheels responsive to the second target change in delta velocity (402-418).

8. A control method according to claim 7, wherein said one wheel and said another of the wheels are both front wheels of the vehicle.

9. In a vehicle with an active brake control system (52, 54, 56, 58, 68) and a plurality of vehicle wheels (12, 14, 16, 18), wherein the active brake control system has an active state and an inactive state for each wheel, the active brake control system comprising:

a yaw rate sensor (80) providing an output signal indicative of measured vehicle yaw rate;

a plurality of speed sensors (28, 30, 32, 34) providing sensor signals indicative of rotational velocities of the vehicle wheels;

controller (68) coupled to the speed and yaw rate sensors, wherein the controller determines individual wheel speeds responsive to the sensor signals, wherein the controller includes

(a) a signal summer for determining a difference between the individual wheel speed for one of the wheels and a vehicle reference speed (326);

(b) a filter (326), having a filter gain, receiving the difference output from the signal summer and providing a filter output;

(c) a gain control (316-324) for the filter, wherein the gain control changes the filter gain when the active brake control system is in the active state for the one of the wheels so that the filter output does not change during the active state for the one of the wheels,

wherein the controller determines a control signal (1116) for a wheel brake for the one of the wheels responsive to the filter output, the difference signal, and the measured vehicle yaw rate.