Control of a steering wheel system with passive resistance torque
View Patent ↗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.
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.