Steering systems and methods for generating haptic feel torque

1. A method for generating haptic feel torque for a steering system for an automotive vehicle, the method comprising:

inputting a steering command signal by manipulating a steering wheel mounted to a steering column of the automotive vehicle;

in response to the steering command, changing an orientation of road wheels of the automotive vehicle;

communicating condition data of the road wheels to a controller;

calculating with the controller a turning acceleration of the steering column in response to changing the orientation of the road wheels by modeling a virtual spring and a virtual damper interconnected between the steering column and the road wheels based on the condition data; and

applying the turning acceleration to the steering column.

2. The method of claim 1 wherein the vehicle includes a steering angle sensor, a motor, and a road wheel sensor, and wherein the method comprises:

identifying the steering command with the steering angle sensor;

communicating the steering command from the steering angle sensor to the motor, wherein the motor changes the orientation of road wheels of the automotive vehicle; and

obtaining the condition data of the road wheels with the road wheel sensor.

3. The method of claim 1 wherein the vehicle includes a haptic generator coupled to the steering column, wherein the haptic generator is directed by the controller to apply the turning acceleration to the steering column.

4. The method of claim 1 wherein the vehicle includes a haptic generator coupled to the steering column via a mechanism, wherein the haptic generator is directed by the controller to apply the turning acceleration to the steering column through the mechanism.

5. The method of claim 1 wherein calculating with the controller the turning acceleration of the steering column in response to changing the orientation of the road wheels by modeling the virtual spring and the virtual damper interconnected between the steering column and the road wheels based on the condition data comprises calibrating a virtual spring constant and a virtual damping coefficient.

6. The method of claim 1 wherein calculating with the controller the turning acceleration of the steering column in response to changing the orientation of the road wheels by modeling the virtual spring and the virtual damper interconnected between the steering column and the road wheels based on the condition data comprises calibrating a virtual spring constant and a virtual damping coefficient.

7. The method of claim 1 wherein calculating with the controller the turning acceleration of the steering column in response to changing the orientation of the road wheels by modeling the virtual spring and the virtual damper interconnected between the steering column and the road wheels based on the condition data comprises calculating the turning acceleration, {umlaut over (θ)} haptic , according to the equation:

θ

¨

haptic

=

-

k

vir

I

upper

⁢

(

θ

target

-

θ

lower

+

θ

upper

)

-

c

vir

I

upper

⁢

(

θ

.

lower

+

θ

.

upper

)

wherein:

k vir is a virtual spring constant; c vir is a virtual damping coefficient;

I upper is steering column inertia; and θ upper is the angle of the upper steering column;

θ lower is the angle of the lower steering column; θ target is the commanded steering angle;

{dot over (θ)} lower is the angular velocity of the lower steering column; and {dot over (θ)} upper is the angular velocity of the upper steering column.

8. The method of claim 1 wherein the vehicle includes a steering angle and/or angle rate sensor and a road wheel sensor, and wherein the method comprises:

identifying the steering command with the steering angle sensor; and

obtaining the condition data of the road wheels with the road wheel sensor; wherein calculating with the controller the turning acceleration of the steering column in response to changing the orientation of the road wheels by modeling the virtual spring and the virtual damper interconnected between the steering column and the road wheels based on the condition data comprises calculating the turning acceleration, {umlaut over (θ)} haptic , according to the equation:

θ

¨

haptic

=

-

k

vir

I

upper

⁢

(

θ

target

-

θ

lower

+

θ

upper

)

-

c

vir

I

upper

⁢

(

θ

.

lower

+

θ

.

upper

)

wherein:

k vir is a virtual spring constant; c vir is a virtual damping coefficient;

I upper is steering column inertia; θ upper is the angle of the upper steering column;

{dot over (θ)} upper is the angular velocity of the upper steering column;

θ lower is the angle of the lower steering column; and

{dot over (θ)} lower is the angular velocity of the lower steering column.

9. A method for generating haptic feel torque for a steering system for an automotive vehicle, the method comprising:

inputting a steering command signal by manipulating a steering wheel mounted to a steering column of the automotive vehicle;

in response to the steering command, changing an orientation of road wheels of the automotive vehicle;

communicating condition data of the road wheels to a controller;

calculating with the controller a turning acceleration of the steering column in response to changing the orientation of the road wheels by modeling system components from standard steering tests and by estimating selected parameters of the steering system; and

applying the turning acceleration to the steering column.

10. The method of claim 9 wherein the vehicle includes a steering angle sensor, a motor, and a road wheel sensor, and wherein the method comprises:

identifying the steering command with the steering angle sensor;

communicating the steering command from the steering angle sensor to the motor, wherein the motor changes the orientation of road wheels of the automotive vehicle; and

obtaining the condition data of the road wheels with the road wheel sensor.

11. The method of claim 10 wherein the vehicle includes an element mechanically coupled to the road wheels, and wherein the motor changes the orientation of road wheels of the automotive vehicle by laterally displacing the element.

12. The method of claim 9 wherein the vehicle includes a haptic generator coupled to the steering column, wherein the haptic generator is directed by the controller to apply the turning acceleration to the steering column.

13. The method of claim 9 wherein the vehicle includes a haptic generator coupled to the steering column via a belt and pulley mechanism, wherein the haptic generator is directed by the controller to apply the turning acceleration to the steering column through the belt and pulley mechanism.

14. The method of claim 9 wherein the selected parameters of the steering system include I equ , c equ and k equ .

15. The method of claim 9 wherein the selected parameters are estimated by approximating the selected parameters in a second order equivalent system.

16. The method of claim 9 wherein the selected parameters are approximated in the equation:

T haptic =I equ {umlaut over (θ)}+c equ {dot over (θ)}+k equ θ+T EPS +T SelfAlign

wherein T haptic is the calculated steering column torque, and I equ , c equ and k equ are determined from experimental data sets.

17. The method of claim 9 wherein the selected parameters are approximated in the equation:

T haptic =I equ {umlaut over (θ)}+c equ {dot over (θ)}+k equ θ+T EPS +T SelfAlign

wherein T haptic is the calculated steering column torque, and I equ , c equ and k equ are determined from experimental data sets; and

wherein θ 1 , {dot over (θ)} 1 , and {umlaut over (θ)} 1 are measurements of the steering wheel or road wheels.

18. The method of claim 9 wherein a first equation for calculating the turning acceleration of the steering column is used at low speeds and a second equation for calculating the turning acceleration of the steering column is used at high speeds.

19. The method of claim 9 wherein a selected equation for calculating the turning acceleration of the steering column is used at a selected vehicle speed.

20. A steering system for an automotive vehicle that includes road wheels and an element mechanically coupled to the road wheels and displaceable to change an orientation of the road wheels, the steering system comprising:

a steering wheel mounted on a steering column and rotatable for inputting a steering command;

a steering angle sensor for identifying the steering command;

a motor for displacing the element to change the orientation of the road wheels;

a road wheel sensor for obtaining road wheel condition data;

a haptic generator coupled to the steering column for applying a turning acceleration thereto; and

a controller for receiving the steering command data and the road wheel condition data and for calculating the turning acceleration to be applied to the steering column by modeling a virtual spring and a virtual damper interconnected between the steering column and the road wheels based on the condition data or by modeling system components from standard steering tests and by estimating selected parameters of the steering system.