Rack-limiting condition detection and the corresponding steering wheel torque feedback for steer by wire steering systems

1. A steer-by-wire steering system configured to detect a rack/roadwheel-limiting condition or a vehicle limiting condition, the steer-by-wire steering system comprising:

a processor configured to:

receive input signals comprising a handwheel velocity signal and a vehicle speed signal;

determine a simulated left end stop position of a rack based on the input signals;

determine a simulated right end stop position of a rack based on the input signals;

compare a rack position with the simulated left end stop position and the simulated right end stop position; and

generate a feedback signal based on a determination that the rack position is not within a range that is bound by the simulated left end stop position and the simulated right end stop position.

2. The steer-by-wire steering system of claim 1 , wherein determining the simulated left end stop position and the simulated right end stop position comprises:

determining a rack limiting threshold based on the handwheel velocity signal and the rack velocity signal.

3. The steer-by-wire steering system of claim 2 , wherein determining the simulated left end stop position comprises: simulated left end stop position=max (rack position−rack limiting threshold, left mechanical rack limit), where the left mechanical rack limit is a predetermined value.

4. The steer-by-wire steering system of claim 2 , wherein determining the simulated right end stop position comprises: simulated right end stop position=min (rack position+rack limiting detection threshold, right mechanical rack limit), where the right mechanical rack limit is a predetermined value.

5. The steer-by-wire steering system of claim 1 , wherein the processor is further configured to adjust a commanded rack position based on the feedback signal.

6. The steer-by-wire steering system of claim 1 , wherein the processor is further configured to generate a handwheel torque based on the feedback signal.

7. The steer-by-wire steering system of claim 1 , wherein the processor is further configured to perform a vehicle maneuver based on the feedback signal.

8. A method to detect a rack/roadwheel-limiting condition or a vehicle limiting condition, the method comprising:

receiving input signals comprising a handwheel velocity signal and a vehicle speed signal;

determining a simulated left end stop position of a rack based on the input signals;

determining a simulated right end stop position of a rack based on the input signals;

comparing a rack position with the simulated left end stop position and the simulated right end stop position; and

generating a feedback signal based on a determination that the rack position is not within a range bound by the simulated left end stop position and the simulated right end stop position.

9. The method of claim 8 , wherein determining the simulated left end stop position and the simulated right end stop position comprises:

determining a rack limiting threshold based on the handwheel velocity signal and the vehicle speed signal.

10. The method of claim 9 , wherein determining the simulated left end stop position comprises: simulated left end stop position=max (rack position−rack limiting threshold, left mechanical rack limit), where the left mechanical rack limit is a predetermined value.

11. The method of claim 9 , wherein determining the simulated right end stop position comprises: simulated right end stop position=min (rack position+rack limiting detection threshold, right mechanical rack limit), where the right mechanical rack limit is a predetermined value.

12. The method of claim 8 , further comprising adjusting a commanded rack position based on the feedback signal.

13. The method of claim 8 , further comprising generating a handwheel torque based on the feedback signal.

14. The method of claim 8 , further comprising performing a vehicle maneuver based on the feedback signal.

15. A computer program product comprising a computer readable storage device having stored therein one or more computer executable instructions, which when executed by a processor perform a method to detect a rack/roadwheel-limiting condition or a vehicle limiting condition, the method comprising:

receiving input signals comprising a handwheel velocity signal and a vehicle speed signal;

determining a simulated left end stop position of a rack based on the input signals;

determining a simulated right end stop position of a rack based on the input signals;

comparing a rack position with the simulated left end stop position and the simulated right end stop position; and

generating a feedback signal based on a determination that the rack position is not within a range bound by the simulated left end stop position and the simulated right end stop position.

16. The computer program product of claim 15 , wherein determining the simulated left end stop position and the simulated right end stop position comprises:

determining a rack limiting threshold based on the handwheel velocity signal and the vehicle speed signal.

17. The computer program product of claim 16 , wherein determining the simulated left end stop position comprises: simulated left end stop position=max (rack position−rack limiting threshold, left mechanical rack limit), where the left mechanical rack limit is a predetermined value.

18. The computer program product of claim 16 , wherein determining the simulated right end stop position comprises: simulated right end stop position=min (rack position+rack limiting detection threshold, right mechanical rack limit), where the right mechanical rack limit is a predetermined value.

19. The computer program product of claim 15 , wherein the method further comprises generating a handwheel torque based on the feedback signal.

20. The computer program product of claim 15 , wherein the method further comprises performing a vehicle maneuver based on the feedback signal.