Electric power steering control methods and systems

1. A control system for controlling a steering system, the control system comprising:

a first module that receives as input handwheel velocity and handwheel torque and determines a direction of assist modification based on the handwheel torque if the handwheel velocity is below a first threshold, and the first module determines a hysteresis position based on handwheel velocity, the direction of assist modification, and handwheel torque;

a second module that selectively determines an assist curve based on the hysteresis position; and

a third module that generates a final assist command based on the assist curve.

2. The control system of claim 1 , wherein the first module determines the direction based on handwheel velocity when the handwheel velocity is above a second threshold.

3. The control system of claim 2 , wherein the first module determines the direction based on a blending method when the handwheel velocity is between the first threshold and the second threshold.

4. The control system of claim 1 , wherein the first module converts the handwheel velocity to a torque value.

5. The control system of claim 1 , wherein the third module generates the final assist command based on at least one of an upper limit and a lower limit on the assist curve.

6. A method of controlling a steering system, the method comprising:

receiving handwheel velocity and handwheel torque by a first module;

determining a direction of assist modification based on the handwheel torque if the handwheel velocity is below a first threshold by the first module;

determining a hysteresis position based on handwheel velocity, the direction of assist modification, and handwheel torque by the first module;

selectively determining an assist curve based on the hysteresis position by a second module; and

generating a final assist command to the steering system based on the assist curve by a third module.

7. The method of claim 6 , wherein determining the direction is based on handwheel velocity when the handwheel velocity is above a second threshold.

8. The method of claim 7 , wherein determining the direction is based on a blending method when the handwheel velocity is between the first threshold and the second threshold.

9. The method of claim 6 , further comprising converting the handwheel velocity to a torque value.

10. The method of claim 6 , wherein generating the final assist command is based on at least one of an upper limit and a lower limit on the assist curve.

11. A system in a vehicle, comprising:

an electric power steering system; and

a control module that receives as input handwheel velocity and handwheel torque and determines a direction of assist modification based on the handwheel torque if the handwheel velocity is below a first threshold, that determines a hysteresis position based on handwheel velocity, the direction of assist modification, and handwheel torque, that selectively determines an assist curve based on the hysteresis position, and that generates a final assist command based on the assist curve.

12. The system of claim 11 , wherein the control module determines the direction based on handwheel velocity when the handwheel velocity is above a second threshold.

13. The system of claim 12 , wherein the control module determines the direction based on a blending method when the handwheel velocity is between the first threshold and the second threshold.

14. The system of claim 11 , wherein the control module converts the handwheel velocity to a torque value.

15. A method of controlling a steering system, the method comprising:

receiving handwheel velocity and handwheel torque by a first module;

determining a direction of assist modification, the direction of assist modification based on the handwheel torque if the handwheel velocity is below a first threshold, the direction of assist modification based on based on the handwheel velocity if the handwheel velocity is above a second threshold, and the direction of assist modification based on a blending method if the handwheel velocity is between the first threshold and the second threshold; and

determining a hysteresis position based on handwheel velocity, the direction of assist modification, and handwheel torque by the first module.