Method for position regulation of an electric drive and for steering a motor vehicle by means of a steer-by-wire system

• US 6,879,118 B2
• Filed: 02/06/2002
• Issued: 04/12/2005
• Est. Priority Date: 02/06/2001
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH, ZF Lenksysteme GmbH (Robert Bosch GmbH)
• Original Assignee: Robert Bosch GmbH
• Inventors: Cao, Chi-Thuan, Blessing, Petral
• Primary Examiner(s): Martin, David
• Assistant Examiner(s): Santana, Eduardo Colon
• Application Number:
  US10/240,898
• Publication Number:
  US 20030169003A1
• Time in Patent Office: 1,161 Days
• Field of Search: 180/405, 180/412, 180/403, 180/415, 180/422, 180/446, 180/443, 180/6.2, 180/6.28, 318/34, 318/139, 318/434, 318/432, 701/41, 701/42
• US Class Current: 318/34
• CPC Class Codes: B62D 5/092 the electric motor being connected to the final driven element of the steering gear, e.g. rack
• CPC Class Codes: B62D 6/002 computing target steering angles for front or rear wheels B62D7/159 takes precedence
• 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 method for steering a motor vehicle with a steer-by-wire steering system. A setpoint is for the position of the steered wheels is generated from the steering wheel angle. A controlled difference is then generated between the setpoint and the actual value of the position of the steered wheel and the position of the steered wheel is then adjusted in accordance with the controlled difference. The steering wheel torque is then adjusted based on the torque'"'"'s and/or forces prevailing between the steered wheels and a steering controller or based on a performance graph.

Claims

1. A method for positionally controlling an electric drive of a vehicle, said vehicle including a steering element and an electric drive, said method comprising:

determining the actual position of a steering element;

converting said actual position into a setpoint for the position of an electric drive;

detecting an actual value of the position of the electric drive;

generating a control difference between the setpoint and the actual value;

adjusting the position of the electric drive based on the control difference; and

generating a restoring force for acting on the steering element from one of the forces acting on the electric drive, and a family of characteristic curves.

2. A method for steering a motor vehicle, said vehicle including a steering wheel, a plurality of steered wheels, and a steering controller, said method comprising:

detecting a steering wheel angle;

generating a setpoint for the position of the steered wheels from said detected steering wheel angle;

detecting an actual value of the position of said steered wheels;

generating a control difference between said setpoint and said detected actual value;

adjusting the position of said steered wheels based on said control difference; and

adjusting a steering wheel torque based on one of the forces prevailing between the steered wheels and a steering controller, and a performance graph.

3. A control for a steer-by-wire system of a vehicle, said vehicle including steered wheels, a steering box, and a tie rod, said control comprising:

a steering wheel;

a steering column;

a rotation-angle sensor;

a steering-wheel motor acting on said steering column; and

a steering actuator acting on the steered wheels by means of the steering box and the tie rod, and wherein said control operates according to the method of claim 2.

4. A method for steering a motor vehicle, said vehicle including a steering wheel, a plurality of steered wheels, a steering controller, a first controller, a compensator, a motor controller, and a hydraulic steering system which includes a valve actuator, said method comprising:

detecting a steering wheel angle;

generating a setpoint for the position of the steered wheels from said detected steering wheel angle;

detecting an actual value of the position of said steered wheels;

generating a control difference between said setpoint and said detected actual value;

adjusting the position of said steered wheels based on said control difference;

outputting from said first controller, as a manipulated variable derived from said control difference, a first setpoint of said valve actuator;

outputting from said compensator, in parallel with said first controller, as a manipulated variable derived from said setpoint for the position of said steered wheels, a second setpoint of said valve actuator;

adding said first setpoint and said second setpoint to yield a third setpoint of said valve actuator;

establishing said third setpoint as the reference variable of a motor controller; and

adjusting a steering wheel torque based on one of the forces prevailing between the steered wheels and a steering controller, and a performance graph.

5. The method of claim 4 wherein said vehicle steering system includes a pinion, and said vehicle includes an integrator, said method further characterized in:

that in said first controller said control difference is amplified according to the rotation angle of the pinion in a region of a center position of the pinion; and

that the product of said control difference and said amplification is integrated in an integrator to yield said first setpoint.

6. The method of claim 5 characterized in that the steering wheel torque setpoint is generated according to the difference between said rotation angle of said valve actuator and the rotation angle of the pinion.

7. The method of claim 6 wherein said vehicle includes a steering box, said method further characterized in that a transmission ratio of the hydraulic system is taken into account in the generation of said difference between said rotation angle of said valve actuator and said rotation angle of the pinion.

8. A steer-by-wire system for a vehicle, said vehicle including steered wheels, a steering box, and a tie rod, said system comprising a steering wheel, a steering column, a rotation-angle sensor, a steering-wheel motor acting on said steering column, a steering actuator acting on the steered wheels by means of a steering box and the tie rod, and a control which operates in accordance with the method of claim 7.

9. The steer-by-wire system of claim 8 further characterized in that said steering box is a hydraulics-steering box comprising a torsion-bar valve.

10. The steer-by-wire system of claim 8 further characterized in that said steering-wheel motor acts on said steering wheel by way of a gearbox.

11. The method of claim 4 wherein said vehicle further includes a master controller and a slave controller, said method further characterized in:

that said motor controller is a cascade controller comprising a master controller and at least one slave controller; and

that a control difference of said master controller is generated from said third setpoint and the actual value of a rotation angle of said valve actuator.

12. The method of claim 11, further characterized in:

that said master controller is a position controller;

that the manipulated variable of said master controller is a rotation speed setpoint of said valve actuator;

that said control difference of said first slave controller which comprises a rotation speed controller is derived from a setpoint rotation speed and an actual rotation speed of said valve actuator; and

that the manipulated variable of said rotation-speed controller is a torque setpoint of said valve actuator.

13. The method of claim 12 wherein said vehicle further includes a torsion bar valve, said method further characterized in:

that a first disturbance variable is subtracted from said manipulated variable of said master controller; and

that said first disturbance variable is calculated according to the following equation;

M_dist1=C_{torsion bar}(δ

_pinion−

δ

_{VA, actual}),

wherein;

C_{torsion bar} is a torsion spring rate of the torsion-bar valve.

14. The method of claim 13 further characterized in that said steering-wheel torque setpoint is determined based on one of the actual current of said valve actuator and a performance graph.

15. The method of claim 12 further characterized in:

that a damping torque is subtracted from said manipulated variable of said master controller; and

that said damping torque is calculated according to the following equation;

M_damp=D(ω

_pinion−

ω

_{VA, actual}),

wherein;

D is a constant

T is a rotation speed.

16. The method of claim 12 further characterized in:

that said manipulated variable of said first slave controller is a torque setpoint of said valve actuator; and

that a current setpoint of said valve actuator is generated from said torque setpoint by means of a torque/current characteristic.

17. The method of claim 12 wherein said vehicle further includes a second slave controller, the method further characterized in:

that said control difference of a second slave controller which comprises a torque controller, is generated from said torque setpoint and said actual torque of said valve actuator.

18. The method of claim 17 wherein said vehicle includes a third slave controller and a frequency converter, said method further characterized in:

that said control difference of a third slave controller which comprises a current controller is generated from said current setpoint and said actual current of said valve actuator; and

that said third slave controller drives said valve actuator by means of a frequency converter.

19. The method of claim 4 further characterized in that the generation of the setpoint for the position of the steered wheels is performed in a speed-dependent manner.

20. The method of claim 4 wherein said vehicle includes a tracking controller, said method further characterized in that a first correction angle is superimposed on said steering-wheel angle by a tracking controller based on a steering-wheel course angle.

21. The method of claim 20 wherein said vehicle includes a steering-wheel controller, the method further characterized in that said steering-wheel torque is adjusted by means of said steering-wheel controller.

22. The method of claim 4 wherein said vehicle includes a vehicle-dynamics controller, said method further characterized in that a second correction angle is superimposed on said steering-wheel angle by a vehicle-dynamics controller based on at least one of the road speed, the transverse acceleration, and the yaw rate of the vehicle.