Brake system control

• US 6,547,343 B1
• Filed: 09/08/1997
• Issued: 04/15/2003
• Est. Priority Date: 09/08/1997
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated), General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Hac, Aleksander Boguslaw
• Primary Examiner(s): Lavinder, Jack
• Assistant Examiner(s): SY, MARIANO ONG
• Application Number:
  US08/925,247
• Time in Patent Office: 2,045 Days
• Field of Search: 303/146, 303/147, 303/148, 303/149, 303/150, 303/140
• US Class Current: 303/146
• CPC Class Codes: B60T 2210/22 Banked curves
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• CPC Class Codes: B60T 2270/86 Optimizing braking by using ESP vehicle or tire model
• 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

A brake system control method, comprising the steps of: measuring a set of vehicle parameters including steering wheel angle, vehicle speed, lateral acceleration and vehicle yaw rate; responsive to the measured parameters using an observer to estimate lateral velocity of the vehicle, wherein the observer contains (a) an open loop dynamic model of the vehicle responsive to the measured vehicle speed and the measured yaw rate, (b) a closed loop term responsive to a first error between the measured yaw rate and a predicted yaw rate, a second error between a previously estimated lateral velocity and a predicted lateral velocity and a third error between the measured lateral acceleration and a predicted lateral acceleration; estimating a vehicle slip angle responsive to the estimate of lateral velocity; determining a control command responsive to the vehicle slip angle; and controlling an actuator responsive to the control command.

Claims

1. A brake system control method, comprising the steps of:

measuring a set of vehicle parameters including steering wheel angle, vehicle speed, lateral acceleration and vehicle yaw rate;

responsive to the measured parameters using an observer to estimate lateral velocity of the vehicle, wherein the observer contains

(a) an open loop nonlinear dynamic model of the vehicle responsive to the measured vehicle speed and the measured yaw rate;

(b) a closed loop term responsive to a first error between the measured yaw rate and a predicted yaw rate, a second error between a previously estimated derivative of lateral velocity and a predicted derivative of lateral velocity and a third error between the measured lateral acceleration and a predicted lateral acceleration;

estimating a vehicle slip angle responsive to the estimate of lateral velocity;

determining a control command responsive to the vehicle slip angle; and

controlling an actuator responsive to the control command.

2. A brake system control method according to claim 1, wherein the closed loop term of the observer is also responsive to a fourth error determined by low-pass filtering the third error, wherein the measured lateral acceleration is measured in a direction lateral to a body of the vehicle and wherein bank angles of the road surface are compensated for.

3. A brake system control method according to claim 1, also comprising the step of:

responsive to the measured parameters, estimating a coefficient of adhesion between vehicle wheels and a road surface, wherein the open loop nonlinear dynamic model of the vehicle is also responsive to the estimated coefficient of adhesion.

4. A brake system control method comprising the steps of:

estimating a front side slip angle of front vehicle wheels;

estimating a rear side slip angle of rear vehicle wheels;

estimating a first lateral force of the front wheels on a road surface responsive to the first side slip angle;

estimating a second lateral force of the rear wheels on the road surface responsive to the second side slip angle, wherein the first lateral force estimation is responsive to a first function for low values of the front side slip angle and responsive to a second function for high values of the front side slip angle, wherein the second lateral force estimation is responsive to a third function for low values of the rear side slip angle and responsive to a fourth function for high values of the rear side slip angle, wherein the first and third functions are similar to a parabolic segment and wherein the second and fourth functions include a straight line;

estimating a vehicle lateral velocity responsive to the first and second lateral force estimation;

estimating a vehicle slip angle responsive to the vehicle lateral velocity and a vehicle forward velocity;

determining a control command responsive to the estimated vehicle slip angle; and

controlling a chassis system actuator responsive to the control command.

5. A brake system control method according to claim 4, wherein the first lateral force estimation is responsive to the first function when a first product of the first side slip angle and an estimate of surface coefficient of adhesion is below a first threshold and responsive to the second function when the first product is not below the first threshold, and the second lateral force estimation is responsive to the second function when a second product of the second side slip angle and the estimate of surface coefficient of adhesion is below a second threshold and responsive to the fourth function when the second product is not below the second threshold.