Real-time vehicle dynamics estimation system

• US 20050278077A1
• Filed: 06/09/2004
• Published: 12/15/2005
• Est. Priority Date: 06/09/2004
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Shin, Kwang-Keun, Chin, Yuen-Kwok
• Granted Patent: US 7,349,778 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: B60W 2050/0028 Mathematical models, e.g. for simulation
• CPC Class Codes: B60W 2510/20 Steering systems
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 30/02 Control of vehicle driving stability
• CPC Class Codes: B60W 30/045 Improving turning performance
• CPC Class Codes: B60W 40/12 related to parameters of the vehicle itself , e.g. tyre models
• CPC Class Codes: B62D 6/007 adjustable by the driver, e.g. sport mode

Abstract

A real-time vehicle dynamics estimation system that employs a vehicle parameter estimator, a vehicle condition detector and a rich steering input detector for estimating vehicle understeer coefficient and front and rear cornering compliances in real time. The vehicle parameter estimator receives a front wheel steering angle signal, a rear wheel steering angle signal, a vehicle lateral acceleration signal, a vehicle yaw rate signal and a vehicle speed signal, and employs a linear parameter estimation algorithm for estimating the understeer coefficient, and the front and rear corning compliance. The vehicle condition detector receives the front wheel steering angle signal, the rear wheel steering angle signal, the vehicle yaw rate signal and the vehicle speed signal, and disables the vehicle parameter estimator if the vehicle is not operating in a linear region. The rich steering input detector receives the front wheel angle signal, the rear wheel angle signal and the vehicle speed signal, and provides an output signal indicating whether the estimated vehicle parameters are reliable and are ready to be used.

Claims

1. An estimation system for determining estimated vehicle dynamics parameters, said system comprising:

a vehicle parameter estimator responsive to input signals including a front wheel steering angle signal, a rear wheel steering angle signal, a vehicle lateral acceleration signal, a vehicle yaw rate signal and a vehicle speed signal, said vehicle parameter estimator employing a linear parameter estimation algorithm for estimating true vehicle parameters;

a vehicle condition detector responsive to the front wheel steering angle signal, the rear wheel steering angle signal, the vehicle yaw rate signal and the vehicle speed signal, said vehicle condition detector disabling the vehicle parameter estimator if the vehicle is not operating in a linear region; and

a rich steering input detector responsive to the front wheel angle signal, the rear wheel angle signal and the vehicle speed signal, said rich steering input detector providing an output signal indicating whether the estimated parameters are reliable enough and are ready to be used.

2. The system according to claim 1 wherein the estimated vehicle parameters include a vehicle understeer coefficient, a front cornering compliance and a rear cornering compliance.

3. The system according to claim 1 wherein the vehicle parameter estimator converts the input signals to parameter estimator converted values, executes the linear parameter estimation algorithm based on the converted values to generate estimation values, and calculates the vehicle parameters based on the estimation values.

4. The system according to claim 3 wherein the vehicle parameter estimator converts the input signals to parameter estimator converted values by filtering the signals, integrating the signals and generating regression vectors.

5. The system according to claim 3 wherein the vehicle parameter estimator determines if a steady state turning condition is met.

6. The system according to claim 1 wherein the parameter estimation algorithm is selected from the group consisting of recursive least squares algorithms and Lyapunov-based algorithms.

7. The system according to claim 1 wherein the vehicle condition detector determines whether the vehicle is operating in the linear region by determining whether the vehicle is traveling at a fast enough speed, whether the vehicle is accelerating or decelerating too quickly and whether the vehicle yaw rate is too great.

8. The system according to claim 7 wherein the vehicle condition detector determines if the vehicle yaw rate is too great by comparing the vehicle yaw rate to a reference yaw rate.

9. The system according to claim 1 wherein the rich steering input detector determines a reference model that has pre-defined reference model parameters, provides an estimation of the reference model parameters and compares the estimation of the reference model parameters to the pre-defined reference model parameters.

10. An estimation system for determining estimated vehicle dynamics parameters, said system comprising:

a vehicle parameter estimator, said vehicle parameter estimator employing a linear parameter estimation algorithm for estimating vehicle understeer coefficient, front cornering compliance and rear cornering compliance; and

a vehicle condition detector, said vehicle condition detector disabling the vehicle parameter estimator if the vehicle is not operating in a linear region.

11. The system according to claim 10 wherein the vehicle parameter estimator is responsive a front wheel steering angle signal, a rear wheel steering angle signal, a vehicle lateral acceleration signal, a vehicle yaw rate signal and a vehicle speed signal to estimate the vehicle understeer coefficient, the front cornering compliance and the rear cornering compliance, and the vehicle condition detector receives the front wheel steering angle signal, the rear wheel steering angle signal, the vehicle yaw rate signal and the vehicle speed signal to determine whether the vehicle is operating in the linear region.

12. The system according to claim 10 wherein the vehicle parameter estimator converts input signals to parameter estimator converted values, executes the linear parameter estimation algorithm based on the converted values to generate estimation values, and calculates the understeer coefficient, the front cornering compliance and the rear cornering compliance based on the estimation values.

13. The system according to claim 10 wherein the vehicle condition detector determines whether the vehicle is traveling at a fast enough speed, whether the vehicle is accelerating or decelerating too quickly and whether the vehicle is operating in a linear region.

14. The system according to claim 13 wherein the vehicle condition detector determines if the vehicle is operating in a linear range by comparing the vehicle yaw rate to a reference yaw rate.

15. The system according to claim 10 further comprising a rich steering input detector, said rich steering input detector providing an output signal indicating whether the outputs of the parameter estimator are reliable and are ready to be used.

16. The system according to claim 15 wherein the rich steering input detector determines a reference understeer coefficient, a reference front cornering compliance and a reference rear cornering compliance of a reference model, provides an estimation of the understeer coefficient, the front cornering compliance and the rear cornering compliance of the reference model, and compares the reference understeer coefficient, the reference front cornering compliance and the reference rear cornering compliance of the reference model to the estimated understeer coefficient, the estimated front cornering compliance and the estimated rear cornering compliance of the reference model.

17. A method for determining estimated vehicle dynamics parameters, said method comprising:

estimating the vehicle parameters using input signals including a front wheel steering angle signal, a rear wheel steering angle signal, a vehicle lateral acceleration signal, a vehicle yaw rate signal and a vehicle speed signal and a linear parameter estimation algorithm;

disabling the parameter estimation if the vehicle is not operating in a linear region; and

disregarding the estimated vehicle parameters if a rich steering input condition is not met and the estimated vehicle parameters are not reliable and are not ready to be used.

18. The method according to claim 17 wherein the estimating the vehicle parameters includes estimating a vehicle understeer coefficient, a front cornering compliance and a rear cornering compliance.

19. The method according to claim 17 wherein estimating the vehicle parameters includes converting the input signals to converted values, executing the linear parameter estimation algorithm based on the converted values to generate estimation values, and calculating the vehicle parameters based on the estimation values.

20. The method according to claim 19 wherein converting the input signals to converted values includes filtering the signals, integrating the signals and generating regression vectors.

21. The system according to claim 17 wherein disregarding the estimated vehicle parameters if the vehicle is not operating in a linear region includes disregarding the estimated vehicle parameters if the vehicle is not traveling at a fast enough speed, the vehicle is accelerating or decelerating too quickly or the vehicle is operating in a linear region.