METHOD AND APPARATUS FOR CONTROLLING A VEHICLE COMPUTER MODEL WITH UNDERSTEER

• US 20050125207A1
• Filed: 12/09/2003
• Published: 06/09/2005
• Est. Priority Date: 12/09/2003
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company), Ford Motor Company
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Boyd, Kenneth, Neal, Joseph, Tseng, Eric
• Granted Patent: US 7,689,393 B2
• Time in Patent Office: Days
• US Class Current: 703/8
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• CPC Class Codes: B60T 2270/406 Test-mode; Self-diagnosis
• CPC Class Codes: B60T 2270/86 Optimizing braking by using ESP vehicle or tire model
• CPC Class Codes: B60T 8/885 using electrical circuitry
• CPC Class Codes: B60W 10/20 including control of steering systems
• CPC Class Codes: B60W 2050/0028 Mathematical models, e.g. for simulation
• CPC Class Codes: B60W 30/02 Control of vehicle driving stability
• CPC Class Codes: B60W 30/10 Path keeping cruise control for automatically following a preceding vehicle B60W30/165

Abstract

A simulation system (30) for simulating an operation of an automotive vehicle includes an input (34) providing vehicle information and path information and a controller (38) having a vehicle computer model therein. The controller (38) is programmed to determine a rear side slip angle of a vehicle computer model, when the rear side slip angle is greater than a threshold, determine a look ahead scale factor, when the rear side slip angle is greater than the threshold, increase a look ahead point as a function of the look ahead scale factor, determining a steering wheel angle input to the computer model by comparing the look ahead point and the intended path, and operate the computer model with the steering wheel angle input, and generate an output in response to the vehicle model and the initial steering wheel input or the first steering wheel input.

Claims

1. A simulation system for simulating an operation of an automotive vehicle comprising:

an input providing vehicle information and path information;

a controller having a vehicle computer model therein, said controller programmed to determine a rear side slip angle of a vehicle computer model;

when the rear side slip angle is greater than a threshold, determine a look ahead scale factor;

when the rear side slip angle is greater than the threshold, increase a look ahead point as a function of the look ahead scale factor;

determining a steering wheel angle input to the computer model by comparing the look ahead point and the intended path;

operate the computer model with the steering wheel angle input; and

generate an output in response to the vehicle model and the initial steering wheel input or the first steering wheel input.

2. A system as recited in claim 1 wherein the threshold is about 15 degrees.

3. A method as recited in claim 1 wherein said controller is programmed to determine a longitudinal vehicle velocity and a lateral vehicle velocity and determining the rear side slip angle as a function of the longitudinal vehicle velocity and the lateral vehicle velocity.

4. A system as recited in claim 1 wherein said controller is programmed to determine a look ahead scale factor as a function of the rear side slip angle.

5. A system as recited in claim 1 wherein said controller is programmed to determine a look ahead factor as a function of an exponential of the rear side slip angle.

6. A system as recited in claim 1 wherein said controller is programmed to determine a look ahead factor as a function of an exponential of a product of the rear side slip angle and a constant.

7. A system as recited in claim 6 wherein the constant is about 0.02.

8. A system as recited in claim 1 wherein when the rear side slip angle is not greater that the threshold, determining an unscaled look ahead factor.

9. A system as recited in claim 1 wherein the controller is programmed to determine a steering wheel angle input when the vehicle is not on target.

10. A method of operating a vehicle computer model having vehicle information and path information therein comprising:

determining a rear side slip angle of a vehicle computer model;

when the rear side slip angle is greater than a threshold, determining a look ahead scale factor;

when the rear side slip angle is greater than the threshold, increasing a look ahead point as a function of the look ahead scale factor;

determining a steering wheel angle input to the computer model by comparing the look ahead point and the intended path; and

operating the computer model with the steering wheel angle input.

11. A method as recited in claim 10 wherein the threshold is about 15 degrees.

12. A method as recited in claim 10 wherein determining a rear side slip angle comprises determining a longitudinal vehicle velocity and a lateral vehicle velocity and determining the side slip angle as a function of the longitudinal vehicle velocity and the lateral vehicle velocity.

13. A method as recited in claim 10 wherein determining a look ahead scale factor comprises determining a look ahead factor as a function of the rear side slip angle.

14. A method as recited in claim 10 wherein determining a look ahead scale factor comprises determining a look ahead factor as a function of an exponential of the rear side slip angle.

15. A method as recited in claim 10 wherein determining a look ahead scale factor comprises determining a look ahead factor as a function of an exponential of a product of the rear side slip angle and a constant.

16. A method as recited in claim 15 wherein the constant is about 0.02.

17. A method as recited in claim 10 wherein when the rear side slip angle is not greater that the threshold, determining an unscaled look ahead factor.

18. A method as recited in claim 10 further comprising performing the step of determining a steering wheel angle input when the vehicle is not on target.

19. A method of operating a vehicle computer model having vehicle information and path information therein comprising:

determining a rear side slip angle of a vehicle computer model;

determining a look ahead point;

when the rear side slip angle is greater than a threshold, determining a look ahead scale factor;

when the rear side slip angle is greater than the threshold, increasing the look ahead point as a function of the look ahead scale factor;

when the rear side slip angle is less than the threshold, maintaining the look ahead point;

when the vehicle model is off target, determining a steering wheel angle input to the computer model as a function of an error between the look ahead point and the intended path; and

operating the computer model with the steering wheel angle input.

20. A method as recited in claim 19 wherein determining a look ahead scale factor comprises determining a look ahead factor as a function of an exponential of the rear side slip angle.