Control of a steering wheel system with passive resistance torque

• US 7,295,905 B2
• Filed: 07/29/2004
• Issued: 11/13/2007
• Est. Priority Date: 07/29/2004
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Yao, Yixin, Daugherty, Brian E.
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US10/901,521
• Publication Number:
  US 20060025911A1
• Time in Patent Office: 1,202 Days
• Field of Search: 701/41, 701/42, 701/1, 180/443, 180/402, 180/444, 882/672, 318/342
• US Class Current: 701/41
• CPC Class Codes: B62D 5/006 power actuated
• CPC Class Codes: B62D 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Abstract

A control system and method for a steer-by-wire system with the passive resistance torque is provided. The control system includes a controller configured to compensate for a passive resistance torque and to generate the required active torque using a three loop control structure: torque feedback loop, rate feedback loop, and steering wheel angle feedback loop. The torque feedback loop is based on an estimated steering torque signal calculated from a steering angle signal, a steering angle rate signal, and a motor current signal.

Claims

1. A control system for a steer-by-wire system, the steer-by-wire system having a motor to produce a feedback torque on a steering mechanism, the control system comprising:

a controller configured to compensate for a passive torque of the motor using a torque feedback loop, wherein the torque feedback loop includes a torque estimator that generates an estimated steering torque signal based on the steering wheel angle;

wherein the estimated steering torque is based on a steering angle signal, a steering angle rate signal, and a motor current signal.

2. The control system according to claim 1, wherein the steering angle rate signal is calculated based on a steering wheel angle signal.

3. The control system according to claim 2, wherein the steering wheel angle rate signal is calculated based on the derivative of the steering wheel angle signal.

4. A control system for a steer-by-wire system, the steer-by-wire system having a motor to produce a feedback torque on a steering mechanism, the control system comprising:

a controller configured to compensate for a passive torque of the motor using a torque feedback loop and a rate feedback loop, wherein the torque feedback loop includes a torque estimator that generates an estimated steering torque signal based on the steering wheel angle.

5. The control system according to claim 4, wherein the rate feedback loop is based on a steering wheel angle rate.

6. The control system according to claim 5, wherein the steering wheel angle rate is calculated based on the steering wheel angle.

7. A control system for a steer-by-wire system, the steer-by-wire system having a motor to produce a feedback torque on a steering mechanism, the control system comprising:

a controller configured to compensate for a passive torque of the motor using a torque feedback loop and a steering angle feedback loop, wherein the torque feedback loop includes a torque estimator that generates an estimated steering torque signal based on the steering wheel angle.

8. The control system according to claim 7, wherein the steering angle feedback loop is based on a steering wheel angle and a steering wheel reference angle.

9. A control system for a steer-by-wire system, the steer-by-wire system having a motor to produce a feedback torque on a steering mechanism, the control system comprising:

a controller configured to compensate for a passive torque of the motor using a torque feedback loop, wherein the controller is configured to generate a high torque to simulate a mechanical end stop when the steering wheel angle is larger than ±

θ

_stop, the required stop angle.

10. A control system for a steer-by-wire system, the steer-by-wire system having a motor to produce a feedback torque on a steering mechanism, the control system comprising:

a controller configured to compensate for a passive torque of the motor using a torque feedback loop, wherein the torque feedback loop includes a torque estimator that generates an estimated steering torque signal based on the steering wheel angle;

wherein the controller is configured to prevent an over torque condition by setting a torque saturation level.

11. A control system for a steer-by-wire system, the steer-by-wire system having a motor to produce a feedback torque on a steering mechanism, the control system comprising:

a controller configured to compensate for a passive torque of the motor using a torque feedback loop, wherein the controller provides a control signal to control a steering wheel torque τ

_L, including both a passive resistance torque τ

_t and active torque τ

_a, and the relation of the passive resistance torque τ

_p, the active torque τ

_a, and the steering wheel torque τ

_L, is given as

τ

_L=τ

_p+τ

_a.

12. A control system for a steer-by-wire system, the steer-by-wire system having a motor to produce a feedback torque on a steering mechanism, the control system comprising:

a controller configured to compensate for passive torque and generate active torque, the controller including a torque feedback loop, a rate feedback loop, and a steering angle feedback loop.

13. The control system according to claim 12, wherein the torque feedback loop is based on an estimated steering torque signal.

14. The control system according to claim 13, wherein the estimated steering torque is based on a steering angle signal, a steering angle rate signal, and a motor current signal.

15. The control system according to claim 14, wherein the steering angle rate signal is calculated based on a steering wheel angle signal.

16. The control system according to claim 15, wherein the steering wheel angle rate signal is calculated based on the derivative of the steering wheel angle signal.

17. The control system according to claim 12, wherein the rate feedback loop is based on a steering wheel angle rate.

18. The control system according to claim 17, wherein the steering wheel angle rate is calculated based on the steering wheel angle.

19. The control system according to claim 12, wherein the steering angle feedback loop is based on a steering wheel angle and a steering wheel reference angle.

20. The control system according to claim 12, wherein the controller is configured to generate a high torque to simulate a mechanical end stop when the steering wheel angle is larger than ±

θ

_stop, the required stop angle.

21. The control system according to claim 12, wherein the controller is configured to prevent an over torque condition by setting a torque saturation level.

22. The control system according to claim 12, wherein the controller provides a control signal to control a steering wheel torque τ

_L including both a passive resistance torque τ

_t and active torque τ

_a, and the relation of the passive resistance torque τ

_p, the active torque τ

_a, and the steering wheel torque τ

_L is given as

τ

_L=τ

_p+τ

_a.

23. A method for producing a feedback torque for a steer-by-wire system, the method comprising:

receiving a steering wheel angle;

receiving a motor current;

receiving a vehicle speed;

calculating a steering wheel rate;

estimating a steering wheel torque based on the steering wheel angle, a steering wheel angle rate, and a current signal;

providing a torque feedback loop;

compensating for passive resistance torque; and

generating an active feedback torque.

24. The method according to claim 23, further comprising:

providing a rate feedback loop using a steering wheel rate to generate a damping torque.

25. The method according to claim 24, further comprising:

providing a angular position feedback loop using a steering wheel angle to generate an active feedback torque.