METHOD OF OPERATING AN ELECTRONIC STABILITY CONTROL SYSTEM

• US 20100198445A1
• Filed: 02/04/2009
• Published: 08/05/2010
• Est. Priority Date: 02/04/2009
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: NARDI, Flavio, RYU, Jihan, O'DEA, Kevin A.
• Granted Patent: US 8,886,434 B2
• Time in Patent Office: Days
• US Class Current: 701/29
• CPC Class Codes: B60W 30/02 Control of vehicle driving stability

Abstract

A method of stabilizing a vehicle is provided. The vehicle is travelling at a forward speed and a lateral speed, and comprises a lateral acceleration sensor, a yaw sensor adapted to detect an actual yaw rate of the vehicle around a central axis, a steering mechanism adapted to steer the vehicle by a steered yaw rate, and an electronic stability control system. The method comprises determining the forward speed of the vehicle with the electronic stability control system, determining a yaw error rate based upon a difference between the actual yaw rate of the vehicle and the steered yaw rate, determining the vehicle is in an unstable condition by comparing the yaw error rate to a first predetermined yaw rate, computing a calculated lateral speed based on acceleration data from the lateral acceleration sensor, the forward speed, and the actual yaw rate in response to determining the vehicle is in the unstable condition, calculating a correction factor based on the calculated lateral speed of the vehicle and the forward speed of the vehicle, and adjusting operation of the electronic stability control system by the correction factor.

Claims

1. A method of stabilizing a vehicle travelling at a forward speed and a lateral speed, the vehicle comprising a lateral acceleration sensor, a yaw sensor adapted to detect an actual yaw rate of the vehicle around a central axis, a steering mechanism adapted to steer the vehicle by a steered yaw rate, and an electronic stability control system, the method comprising:

determining the forward speed of the vehicle with the electronic stability control system;

determining a yaw error rate based upon a difference between the actual yaw rate of the vehicle and the steered yaw rate;

determining the vehicle is in an unstable condition by comparing the yaw error rate to a first predetermined yaw rate;

computing a calculated lateral speed based on acceleration data from the lateral acceleration sensor, the forward speed, and the actual yaw rate in response to determining the vehicle is in the unstable condition;

calculating a correction factor based on the calculated lateral speed of the vehicle and the forward speed of the vehicle; and

adjusting operation of the electronic stability control system by the correction factor.

2. The method of claim 1, wherein the steering mechanism comprises a steering sensor and determining the yaw error rate comprises detecting the steered yaw rate using the steering sensor.

3. The method of claim 1, wherein computing the calculated lateral speed comprises performing numerical integration of the acceleration data, forward speed, and actual yaw rate.

4. The method of claim 3, wherein computing the calculated lateral speed of the vehicle based on acceleration data from the lateral acceleration sensor, forward speed, and actual yaw rate comprises:

calculating a plurality of values of a derivative of the lateral speed; and

calculating a sum of the plurality of values of the derivative of the lateral speed measured, each multiplied by the interval of time, the calculation performed while the vehicle is in the unstable condition.

5. The method of claim 1, wherein adjusting operation of the electronic stability control system comprises calculating the correction factor from a ratio of the calculated lateral speed to the forward speed and comparing the ratio to a predetermined value.

6. The method of claim 1, the method further comprising:

calculating the yaw error rate while performing the step of adjusting operation of the electronic stability control system;

comparing the yaw error rate to a second predetermined yaw rate; and

discontinuing adjustment of operation of the electronic stability control system in response to determining the yaw error rate is below the second predetermined yaw rate.

7. The method of claim 6, wherein the first predetermined yaw rate is greater than the second predetermined yaw rate.

8. A method of adjusting the motion of a vehicle travelling at a forward speed and a lateral speed, the vehicle comprising a lateral acceleration sensor, a yaw sensor adapted to detect an actual yaw rate of the vehicle around a central axis, a steering mechanism adapted to steer the vehicle by a steered yaw rate, and an electronic stability control system, the method comprising:

determining a difference between the steered yaw rate and the actual yaw rate;

comparing the difference to a first predetermined yaw rate;

determining the vehicle is in an unstable condition when the difference exceeds the first predetermined yaw rate;

computing a calculated lateral speed based on acceleration data from the lateral acceleration sensor, the actual yaw rate, and the forward speed in response to determining the vehicle is in an unstable condition, wherein computing the calculated lateral speed comprises performing numerical integration of the acceleration data, the actual yaw rate, and the forward speed;

calculating a correction factor based on the calculated lateral speed and the forward speed of the vehicle; and

adjusting operation of a braking system of the vehicle with the electronic stability control system by the correction factor.

9. The method of claim 8, wherein adjusting operation of the braking system with the electronic stability control system by the correction factor comprises determining a ratio of the calculated lateral speed to the forward speed.

10. The method of claim 9, wherein adjusting operation of the braking system by the correction factor comprises scaling the ratio by a constant amount.

11. The method of claim 8, further comprising:

repeating a comparison of a difference between the steered yaw rate and the actual yaw rate to a second predetermined yaw rate while adjusting operation of the electronic stability control system; and

discontinuing adjustment of operation of the electronic stability control system in response to determining the difference between the steered yaw rate and actual yaw rate is below the second predetermined yaw rate.

12. The method of claim 11, wherein the second predetermined yaw rate is less than the first predetermined yaw rate.

13. The method of claim 8, wherein the vehicle comprises a plurality of wheel assemblies coupled to the braking system and operating the braking system with the electronic stability control system comprises commanding a first amount of braking force for a first of the plurality of wheel assemblies and a second amount of braking force to a second of the plurality of wheel assemblies.

14. The method of claim 13, wherein the first and second amounts of braking force are determined using the correction factor.

15. A stability control system for a vehicle comprising a wheel, the system comprising:

a wheel sensor adapted to determine a rotation rate of the wheel;

a vehicle yaw sensor adapted to determine a rotation rate of the vehicle about a central axis;

a lateral acceleration sensor adapted to detect the acceleration of the vehicle in a direction lateral to the direction of forward travel of the vehicle at a first periodic rate;

a steering device adapted to alter the direction of travel of the vehicle in response to adjustment of its position by an operator of the vehicle;

a steering sensor adapted to detect the position of the steering device and a rate of change of position of the steering device;

an electronic stability control system coupled to the vehicle yaw sensor and to the steering sensor, and adapted to;

receive a first signal from the vehicle yaw sensor, receive a second signal from the steering sensor, and determine the vehicle is in an unstable condition in response to receiving the first and second signals; and

calculate a lateral speed of the vehicle using the first signal, a third signal from the wheel sensor, and a fourth signal from the lateral acceleration sensor.

16. The vehicle of claim 15, wherein the electronic stability control system is further adapted to calculate the lateral speed using numerical integration of signals from the wheel sensor, yaw sensor, and lateral acceleration sensor.

17. The vehicle of claim 15, further comprising:

a plurality of wheel assemblies adapted to support the vehicle and to alter its direction of travel; and

a braking system coupled to at least one of the plurality of wheel assemblies;

wherein the electronic stability control system is adapted to operate the braking system in response to determining the vehicle is in the unstable condition.

18. The vehicle of claim 17, wherein the braking system is coupled to at least two of the plurality of wheel assemblies, and the electronic stability control system is adapted to operate the braking system by commanding different amounts of braking force to each of the at least two of the plurality of wheel assemblies.

19. The vehicle of claim 18, wherein the electronic stability control system is further adapted to operate the braking system in response to a correction factor, the correction factor determined at least in part from the lateral speed of the vehicle.

20. The vehicle of claim 15, wherein the electronic stability control system is further adapted to receive a fifth signal from the vehicle yaw sensor, receive a sixth signal from the steering sensor, and determine the vehicle is in a stable condition in response to receiving the fifth and sixth signals.