DYNAMIC OBSERVER FOR THE ESTIMATION OF VEHICLE LATERAL VELOCITY

• US 20100131229A1
• Filed: 11/24/2008
• Published: 05/27/2010
• 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 Incorporated (General Motors Company)
• Inventors: O'Dea, Kevin A., Ryu, Jihan, Nardi, Flavio, Moshchuk, Nikolai K.
• Granted Patent: US 7,908,112 B2
• Time in Patent Office: Days
• US Class Current: 702/142
• 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 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 that defines a relationship between front and rear axle lateral forces and front and rear axle side-slip angles. The method includes providing measurements of vehicle yaw-rate, lateral acceleration, longitudinal speed, and steering angle. The method also includes using these measurements to provide a measurement of the front and rear axle forces. The method calculates a front axle lateral velocity and a rear axle lateral velocity, and calculates a front axle side-slip angle based on the rear axle lateral velocity and a rear axle side-slip angle based on the front axle lateral velocity. The method then estimates front and rear axle forces, and selects a virtual lateral velocity that minimizes an error between the estimated and measured lateral axle forces. The method then provides an estimated vehicle lateral velocity using the selected virtual lateral velocity.

Claims

1. A method for estimating lateral velocity of a vehicle, said method comprising:

providing measurements of vehicle yaw-rate, lateral acceleration, longitudinal speed, and steering angle;

providing measured front axle lateral forces and rear axle lateral forces based on the measurements of vehicle yaw-rate, lateral acceleration and steering angle;

calculating a front axle lateral velocity and a rear axle lateral velocity;

calculating a front axle side-slip angle based on the rear axle lateral velocity and a rear axle side-slip angle based on the front axle lateral velocity;

estimating front and rear axle forces;

selecting a virtual lateral velocity that minimizes an error between the estimated and measured lateral axle forces; and

providing an estimated vehicle lateral velocity using the selected virtual lateral velocity.

2. The method according to claim 1 wherein calculating the front and rear axle lateral velocities includes using the equations:

v_y^F=v_x tan({circumflex over (α

)}_F^table+δ

)−

ar

v_y^R=v_x tan({circumflex over (α

)}_R^table+δ

)+br

where v_y^F is the front axle lateral velocity, v_y^R is the rear axle lateral velocity, v_x is the vehicle forward speed, α

_F is a front axle side-slip angle, α

_R is a rear axle side-slip angle, δ

is a vehicle steering angle, r is vehicle yaw-rate and a and b are the longitudinal distances of the front and rear axles.

3. The method according to claim 1 wherein calculating the front axle side-slip angle and the rear axle side-slip angle includes using the equations:

4. The method according to claim 1 wherein estimating the front and rear axle forces includes using the equations:

5. The method according to claim 4 wherein the surface coefficient of friction is estimated.

6. The method according to claim 5 wherein the surface coefficient of friction is estimated using the measured yaw-rate, steering angle, vehicle speed, and the front and rear axle forces.

7. The method according to claim 1 wherein selecting the virtual lateral velocity includes using the equation:

8. The method according to claim 1 wherein estimating the vehicle lateral velocity includes using the equation:

9. The method according to claim 8 wherein estimating the lateral velocity includes using a Luenberger observer.

10. A system for estimating lateral velocity of a vehicle, said system comprising:

means for providing measurements of vehicle yaw-rate, lateral acceleration, longitudinal speed, and steering angle;

means for providing measured front axle lateral forces and rear axle lateral forces based on the measurements of vehicle yaw-rate, lateral acceleration and steering angle;

means for calculating a front axle lateral velocity and a rear axle lateral velocity;

means for calculating a front axle side-slip angle based on the rear axle lateral velocity and a rear axle side-slip angle based on the front axle lateral velocity;

means for estimating front and rear axle forces;

means for selecting a virtual lateral velocity that minimizes an error between the estimated and measured lateral axle forces; and

means for providing an estimated vehicle lateral velocity using the selected virtual lateral velocity.

11. The system according to claim 10 wherein the means for calculating the front and rear axle lateral velocities uses the equations:

v_y^F=v_x tan({circumflex over (α

)}_F^table+δ

)−

ar

v_y^R=v_x tan({circumflex over (α

)}_R^table+δ

)+br

where v_y^F is the front axle lateral velocity, v_y^R is the rear axle lateral velocity, v_x is the vehicle forward speed, α

_F is a front axle side-slip angle, α

_R is a rear axle side-slip angle, δ

is a vehicle steering angle, r is vehicle yaw-rate and a and b are the longitudinal distances of the front and rear axles.

12. The system according to claim 10 wherein the means for calculating the front axle side-slip angle and the rear axle side-slip angle uses the equations:

13. The system according to claim 10 wherein the means for estimating the front and rear axle forces uses the equations:

14. The system according to claim 13 wherein the means for estimating estimates the surface coefficient of friction.

15. The system according to claim 14 wherein the means for estimating estimates the surface coefficient of friction using the measured yaw-rate, steering angle, vehicle speed, and the front and rear axle forces.

16. The system according to claim 10 wherein the means for selecting the virtual lateral velocity uses the equation:

17. The system according to claim 10 wherein the means for estimating the vehicle lateral velocity uses the equation:

18. The system according to claim 17 wherein the means for estimating the lateral velocity includes uses a Luenberger observer.

19. A method for estimating lateral velocity of a vehicle, said method comprising:

providing measurements of vehicle yaw-rate, lateral acceleration and steering angle;

providing measured front axle lateral forces and rear axle lateral forces based on the measurements of vehicle yaw-rate, lateral acceleration and steering angle;

calculating a front axle lateral velocity and a rear axle lateral velocity;

calculating a front axle side-slip angle based on the rear axle lateral velocity and a rear axle side-slip angle based on the front axle lateral velocity;

estimating front and rear axle forces including using an estimated surface the coefficient of friction;

selecting a virtual lateral velocity that minimizes an error between the estimated and measured lateral axle forces; and

providing an estimated vehicle lateral velocity using the selected virtual lateral velocity, wherein estimating the lateral velocity includes using a Luenberger observer.

20. The method according to claim 19 wherein estimating the front and rear axle forces includes using the equations: