MOTOR VEHICLE DRIVER ASSISTING METHOD

• US 20090319129A1
• Filed: 06/17/2009
• Published: 12/24/2009
• Est. Priority Date: 06/18/2008
• Status: Abandoned Application

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: GHONEIM, Youssef
• Application Number:
  US12/486,648
• Publication Number:
  US 20090319129A1
• Time in Patent Office: Days
• US Class Current: 701/42
• CPC Class Codes: B60L 2250/16 by display
• CPC Class Codes: B60T 2230/03 Overturn, rollover
• 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 2050/146 Display means
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 2540/18 Steering angle

Abstract

A method is provided for assisting the driver of a motor vehicle that includes, but is not limited to estimating a maximum safe amount of lateral acceleration based on one or more of detected vehicle lateral acceleration, yaw rate, vehicle longitudinal speed and steering wheel angle, calculating a longitudinal vehicle speed to produce a lateral acceleration equal to said maximum safe amount, and displaying a recommended longitudinal vehicle speed to the driver.

Claims

1. A method for assisting a driver of a motor vehicle, comprising the steps of:

estimating a maximum safe amount of a lateral acceleration based on one or more of a vehicle lateral acceleration, a yaw rate, a vehicle longitudinal speed and a steering wheel angle;

calculating a longitudinal vehicle speed to produce the lateral acceleration equal to the maximum safe amount; and

displaying a recommended longitudinal vehicle speed to the driver.

2. The method of claim 1, further comprising the step of estimating a friction coefficient of a road surface.

3. The method of claim 1, wherein the step of estimating comprises the steps of judging, based on a discrepancy between the lateral acceleration or the yaw rate and an expected lateral acceleration or the yaw rate calculated based on the vehicle longitudinal speed and the steering wheel angle, whether the motor vehicle is in a linear regime or in a non-linear regime;

selecting the maximum among a previously stored maximum safe amount and a presently detected vehicle lateral acceleration and storing a selected value as said maximum safe amount if the motor vehicle is judged to be in the linear regime; and

setting a presently detected lateral acceleration as said maximum safe amount if the motor vehicle is judged to be in the non-linear regime.

4. The method of claim 3, wherein the step of estimating further comprises the step of judging whether the motor vehicle has been going straight for a predetermined time and, if so, setting a predetermined value as said maximum safe amount.

5. The method of claim 1, wherein the step of estimating further comprises the step of judging whether the motor vehicle has been going straight for a predetermined time and, if so, setting a predetermined value as said maximum safe amount wherein said predetermined time is between about 50 ms and about 500 ms.

6. The method of claim 1, wherein the step of estimating further comprises the step of judging whether the motor vehicle has been going straight for a predetermined time and, if so, setting a predetermined value as said maximum safe amount, wherein the motor vehicle is judged not to be going straight if the yaw rate rises above a predetermined first limit or the steering wheel angle rises above a predetermined second limit.

7. The method of claim 1, wherein the step of estimating comprises the step of judging whether the motor vehicle has been going straight for a predetermined time and, if so, setting a predetermined value as said maximum safe amount, wherein the motor vehicle is judged to be going straight if the yaw rate drops below a predetermined third limit which is lower than a predetermined first limit or the steering wheel angle drops below a predetermined fourth limit which is lower than a predetermined second limit.

8. The method of claim 1, wherein the step of calculating comprises the steps of:

dividing a current lateral acceleration by the maximum safe amount;

obtaining a square root of a ratio; and

multiplying a current speed by said square root to obtain a first recommended speed.

9. The method of claim 1, wherein the step of estimating comprises the steps of estimating a second recommended speed inversely proportional to a square root of the steering wheel angle.

10. The method of claim 9, wherein the second recommended speed is proportional to the square root of K_μ

+L/V_x², K_μ

being the motor vehicle understeer, L being a distance between front and rear axles of the motor vehicle, and V_x being the motor vehicle speed.

11. The method of claim 1, wherein the step of calculating comprises the steps of determining a first recommended speed dependent on a surface friction coefficient;

determining a second recommended speed dependent on the motor vehicle understeer; and

selecting as said recommended longitudinal vehicle speed the higher one of the first recommended speed and the second recommended speed.

12. The method of claim 11, wherein the step of calculating comprises the steps of:

determining at least one of the first recommended speed dependent on the surface friction coefficient, and the second recommended speed dependent on the motor vehicle understeer;

detecting an official speed limit; and

selecting as said recommended longitudinal vehicle speed at most the smaller one of said recommended longitudinal vehicle speed and said official speed limit.

13. The method of claim 1, wherein the recommended longitudinal vehicle speed is displayed with an intensity dependent on a difference between current and recommended speeds.

14. The method of claim 1, wherein the recommended longitudinal vehicle speed is displayed if it is less than a current speed.

15. The method of claim 1, further comprising the step of lowering a intervention threshold of an ESC system if the recommended longitudinal vehicle speed exceeds a current speed for more than a predetermined time.