Vehicle lateral velocity and surface friction estimation using force tables

• US 8,086,367 B2
• Filed: 11/24/2008
• Issued: 12/27/2011
• Est. Priority Date: 11/24/2008
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Ryu, Jihan, Nardi, Flavio, Moshchuk, Nikolai K., O'Dea, Kevin A.
• Primary Examiner(s): Dickson, Paul N
• Assistant Examiner(s): Frisby, Keith
• Application Number:
  US12/276,996
• Publication Number:
  US 20100131145A1
• Time in Patent Office: 1,128 Days
• Field of Search: 701/29, 701/48, 701/70, 701/71, 701/72, 701/73, 701/74, 701/75, 701/80
• US Class Current: 701/29
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• CPC Class Codes: B60T 2250/04 Vehicle reference speed; Vehicle body speed
• 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

Abstract

A system and method for estimating vehicle lateral velocity and surface coefficient of friction using front and rear axle lateral force versus side-slip angle tables and sensor measurements. The sensor measurements include lateral acceleration, yaw-rate, longitudinal speed and steering angle of the vehicle. The method includes calculating front and rear axle lateral forces and front and rear side-slip angles on the axles of the vehicle. The method also includes identifying two equations from the calculated lateral forces and the vehicle measurements. The method provides tables that identify a relationship between the calculated front and rear axle lateral forces and the front and rear side-slip angles, and determines the vehicle lateral velocity and surface coefficient of friction from the tables.

Claims

1. A method for estimating lateral velocity of a vehicle and surface coefficient of friction, said method comprising:

calculating front and rear axle lateral forces on the vehicle;

calculating front and rear side-slip angles on axles of the vehicle;

identifying two equations from the calculated lateral forces and vehicle measurements;

providing tables that identify a relationship between the calculated front and rear axle lateral forces and the front and rear side-slip angles; and

estimating vehicle lateral velocity and surface coefficient of friction from the tables.

2. The method according to claim 1 wherein calculating the front and rear axle lateral forces includes using vehicle lateral acceleration, yaw-rate, longitudinal speed, and steering angle measurements.

3. The method according to claim 2 wherein the front and rear axle lateral forces are calculated using the equation:

4. The method according to claim 2 wherein the lateral acceleration measurement is compensated for a vehicle roll motion.

5. The method according to claim 1 wherein calculating the front and rear axle side-slip angles includes calculating the front and rear axle side-slip angles based on a kinematic relationship between lateral velocity and axle side-slip angles.

6. The method according to claim 5 wherein calculating the front and rear axle side-slip angles includes using the equations:

7. The method according to claim 1 wherein the two equations are:

8. The method according to claim 1 further comprising preventing estimating of the lateral velocity and the coefficient of friction for an unrealistic solution by solving the two equations with a constraint based on a kinematic relationship between the lateral acceleration and the rate of change of lateral velocity.

9. The method according to claim 8 wherein the constraint is provided as:

10. A method for estimating lateral velocity of a vehicle and estimating surface coefficient of friction, said method comprising:

measuring lateral acceleration, yaw-rate, longitudinal speed, and steering angle of the vehicle;

calculating front and rear axle lateral forces on the vehicle;

calculating front and rear side-slip angles on axles of the vehicle;

providing tables that identify a relationship between the calculated front and rear axle lateral forces and the front and rear side-slip angles; and

determining vehicle lateral velocity and surface coefficient of friction from the tables.

11. The method according to claim 10 wherein the lateral acceleration measurement is compensated for vehicle roll motion.

12. The method according to claim 10 wherein the front and rear axle lateral forces are calculated using the equation:

13. The method according to claim 10 wherein calculating the front and rear axle side-slip angles includes calculating the front and rear axle side-slip angles based on a kinematic relationship between lateral velocity and axle side-slip angles.

14. The method according to claim 13 wherein calculating the front and rear axle side-slip angles includes using the equations:

15. The method according to claim 10 further comprising preventing the determining of the lateral velocity and the coefficient of friction for an unrealistic solution using a constraint based on a kinematic relationship between the lateral acceleration and the rate of change of lateral velocity.

16. The method according to claim 15 wherein the constraint is provided as:

17. A system for estimating lateral velocity of a vehicle and estimating surface coefficient of friction, said system comprising:

means for measuring a lateral acceleration, yaw-rate, longitudinal speed, and steering angle of the vehicle;

means for calculating front and rear axle lateral forces on the vehicle;

means for calculating front and rear side-slip angles on axles of the vehicle;

means for providing tables that identify a relationship between the calculated front and rear axle lateral forces and the front and rear side-slip angles; and

means for determining vehicle lateral velocity and surface coefficient of friction from the tables.

18. The system according to claim 17 further comprising means for compensating for vehicle roll motion.

19. The system according to claim 17 wherein the means for calculating the front and rear axle side-slip angles includes means for calculating the front and rear axle side-slip angles based on a kinematic relationship between lateral velocity and axle side-slip angles.

20. The system according to claim 17 further comprising means for preventing a determination of the lateral velocity in the coefficient of friction for an unrealistic solution using a constraint based on a kinematic relationship between the lateral acceleration and the rate of change of lateral velocity.