Active brake control having yaw rate estimation

• US 6,169,951 B1
• Filed: 08/21/1998
• Issued: 01/02/2001
• Est. Priority Date: 08/21/1998
• Status: Expired due to Term

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated), General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Chin, Yuen-Kwok, Ghoneim, Youssef Ahmed
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US09/138,335
• Time in Patent Office: 865 Days
• Field of Search: 701/70, 701/72, 701/78, 701/82, 701/89, 701/90, 701/41, 701/74, 303/146, 303/139, 303/140, 180/197
• US Class Current: 701/70
• CPC Class Codes: B60T 2250/03 Vehicle yaw rate
• 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 8/17551 determining control parameters related to vehicle stability used in the regulation, e.g. by calculations involving measured or detected parameters

Abstract

An improved vehicle active brake control based on an estimate of vehicle yaw rate, wherein the estimate is based on the speeds of the un-driven wheels, but compensated to reflect slipping of the un-driven wheels during braking. Prior to braking, the yaw rate is estimated solely on the basis of the measured speeds of the un-driven wheels. During braking, the slip speeds of the un-driven wheels are estimated based on the measured speeds, the reference speed of the vehicle and the previous estimate of yaw rate, and used to compute a new yaw rate that is compensated for the estimated slip speeds.

Claims

1. A method of estimating vehicle yaw rate in a vehicle stability enhancement control configured to produce a corrective vehicle yaw moment based on a deviation of the vehicle yaw rate from a desired value, where the vehicle has a pair of un-driven wheels subject to wheel slip during driver braking of the vehicle, and a reference velocity corresponding to an instantaneous velocity of a center of gravity of the vehicle, the method comprising the steps of:

measuring speeds of the un-driven wheels of the vehicle;

estimating the vehicle yaw rate according to a first method based on a difference between the measured wheel speeds;

detecting driver braking of the vehicle; and

during driver braking, estimating the vehicle yaw rate according to a second method that compensates for wheel slip of the un-driven wheels, based on the measured wheel speeds, the vehicle reference velocity, and a previous estimate of the vehicle yaw rate.

2. The method of claim 1, wherein the step of estimating the vehicle yaw rate according to the second method includes the steps of:

estimating slip speeds of the un-driven wheels based on their measured speeds, the vehicle reference velocity, and the previous vehicle yaw rate estimate; and

estimating a new yaw rate value based on the estimated slip speeds, the vehicle reference velocity, and the previous vehicle yaw rate estimate.

3. The method of claim 2, wherein the step of estimating slip speeds includes the steps of:

estimating the slip speed λ

₁ of a first of the un-driven wheels in accordance with the expression (V_m+tΩ

(t−

Δ

T)−

r₁ω

₁)/ (V_m+tΩ

(t−

Δ

T)), where V_m is the vehicle reference velocity, t is a vehicle track dimension, Ω

(t−

Δ

T) is the previous vehicle yaw rate estimate, r₁ is the radius of the first un-driven wheel, and ω

₁ is the measured speed of the first un-driven wheel; and

estimating the slip speed λ

₂ of a second of the un-driven wheels in accordance with the expression (V_m−

tΩ

(t−

Δ

T)−

r₂ω

₂)/ (V_m−

tΩ

(t−

Δ

T)), where r₂ is the radius of the second un-driven wheel, and ω

₂ is the measured speed of the second un-driven wheel.

4. The method of claim 2, wherein the new yaw rate value is estimated in accordance with the expression $\frac{\Omega }{}$



(t-Δ



 



T)+[Vm

(λ

1-λ

2)]/2

t1-(λ

1+λ

2)/2

where Ω

(t−

Δ

T) is the previous vehicle yaw rate estimate, V_m is the vehicle reference velocity, λ

₁ and λ

₂ are the estimated slip speeds of the first and second un-driven wheels, respectively, and t is a vehicle track dimension.