Dynamic system compensator for actively controlled power steering systems

1. A control method for an electric power steering system, comprising:

providing a power steering control signal;

providing a disturbance cancel command based on a rack disturbance;

varying at least one filter based on a frequency of the disturbance cancel command;

applying the at least one varied filter to the disturbance cancel command to generate a compensation signal based on a response to the disturbance cancel command from the steering system;

applying the compensation signal to the power steering control signal to generate a compensated control signal; and

controlling the power steering system to generate a desired assist torque based on the compensated control signal.

2. The method of claim 1 , wherein the varying comprises varying a first filter and a second filter based on the frequency of the disturbance cancel command.

3. The method of claim 2 , wherein the first filter and the second filter are the same filter design.

4. The method of claim 3 , wherein the applying the first filter and the second filter comprises applying the first filter to the disturbance cancel command and applying the second filter to the filtered disturbance cancel command.

5. The method of claim 1 , wherein the varying the at least one filter comprises varying the at least one filter to modify a signal phase.

6. The method of claim 1 , wherein the applying the compensation signal to the power steering control signal comprises adding the compensation signal to the power steering control signal.

7. The method of claim 1 , wherein the steering system comprises a rack that responds to the disturbance cancel command.

8. A system for modifying a steering response in an electric power steering system comprising:

a power steering system; and

a control module configured to control a motor of the power steering system based on a control method, the control method comprising:

providing a power steering control signal;

providing a disturbance cancel command;

varying a first filter and a second filter based on a frequency of the disturbance cancel command;

applying the first varied filter to the disturbance cancel command and applying the second filter to the filtered disturbance cancel command to generate a compensation signal;

applying the compensation signal to the power steering control signal to generate a compensated control signal; and

controlling the power steering system to generate a desired assist torque based on the compensated control signal.

9. The system of claim 8 , wherein the first filter and the second filter are the same filter.

10. The system of claim 8 , wherein the varying the first and second filters comprises varying the first and second filters to modify a signal phase.

11. The system of claim 8 , wherein the applying the compensation signal to the power steering control signal comprises adding the compensation signal to the power steering control signal.

12. The system of claim 8 , wherein the providing a disturbance cancel command is based on a rack disturbance.

13. A control system for a power steering system, comprising:

a power steering control signal module configured to generate a control signal;

a disturbance rejection module configured to generate a disturbance cancel command; and

a compensator module configured to generate a compensated control signal by:

varying at least one filter based on a frequency of the disturbance cancel command that counteracts a rack disturbance;

applying the at least one filter to the disturbance cancel command based on a response to the disturbance cancel command from the steering system;

applying the filtered disturbance cancel command to the control signal; and

controlling the power steering system to generate a desired assist torque based on the compensated control signal.

14. The control system of claim 13 , wherein the compensator module is configured to vary a first filter and a second filter based on the frequency of the disturbance cancel command.

15. The control system of claim 14 , wherein the first filter and the second filter are the same filter design.

16. The control system of claim 13 , wherein the varying the at least one filter comprises varying the at least one filter to modify a signal phase.

17. The control system of claim 13 , wherein the applying the filtered disturbance cancel command to the power steering control signal comprises adding a compensation signal to the power steering control signal, wherein the compensator module is configured to generate the compensation signal by applying the at least one filter to the disturbance cancel command.

18. The control system of claim 13 , wherein the disturbance rejection module is configured to generate a disturbance cancel command based on a rack disturbance.

19. The control system of claim 13 further comprising a rack that responds to the disturbance cancel command.