METHOD FOR OPERATING A STEERING APPARATUS OF A MOTOR VEHICLE COMPRISING AN ELECTROMECHANICAL STEERING-ASSISTANCE DEVICE

• US 20150149038A1
• Filed: 11/20/2014
• Published: 05/28/2015
• Est. Priority Date: 11/26/2013
• Status: Active Grant

• Current Assignee: Dr Ing hc F Porsche AG (Volkswagen AG)
• Original Assignee: Dr Ing hc F Porsche AG (Volkswagen AG)
• Inventors: Krueger, Kim Michael
• Granted Patent: US 9,296,416 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: B62D 5/0472 for damping vibrations
• 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 operating a steering apparatus of a motor vehicle includes detecting interference-induced vibrations which act on a torsion bar of the steering apparatus and analyzing a frequency and amplitude of the interference-induced vibrations. A steering-stabilization function of the steering-assistance device is activated when a limit value for the amplitude of the interference-induced vibrations is exceeded. A drive signal is provided, with the steering stabilization function, for an electric motor of the steering-assistance device, so that the electric motor generates a compensation torque M_bar which acts on the torsion bar and at least partially counteracts the interference-induced vibrations. An indicator is formed from the frequency and the amplitude of the interference-induced vibrations and the carriageway induced vibrations are distinguished from vibrations caused by instabilities in the steering apparatus. The drive signal is generated for the electric motor in a vibration-dependent manner by combining the indicator with the steering-stabilization function.

Claims

1. A method for operating a steering apparatus of a motor vehicle that includes an electromechanical steering-assistance device, the method comprising:

detecting interference-induced vibrations which act on a torsion bar of the steering apparatus;

analyzing a frequency and amplitude of the interference-induced vibrations;

activating a steering-stabilization function of the steering-assistance device when a limit value for the amplitude of the interference-induced vibrations is exceeded;

providing, by the steering stabilization function, a drive signal (AS) for an electric motor of the steering-assistance device, so that the electric motor generates a compensation torque M_bar which acts on the torsion bar and at least partially counteracts the interference-induced vibrations;

forming an indicator (I) from the frequency and the amplitude of the interference-induced vibrations;

distinguishing carriageway-induced vibrations from vibrations caused by instabilities in the steering apparatus; and

generating the drive signal (AS) for the electric motor in a vibration-dependent manner by combining the indicator (I) with the steering-stabilization function.

2. The method as recited in claim 1, wherein the indicator (I) is combined with the steering-stabilization by multiplying.

3. The method as recited in claim 1, wherein the frequency and amplitude of a torsion bar torque (M_DS) of the torsion bar of the steering apparatus are determined so as to form the indicator (I).

4. The method as recited in claim 3, wherein the torsion bar torque (M_DS) is differentiated, and zero crossings in the derivative of the torsion bar torque (M_DS) are detected, the frequency of the vibrations of the torsion bar being calculated from said zero crossings, and also the maximum of a magnitude of the derivative of the torsion bar torque (M_DS) is determined, and the indicator (I) is formed by combining the frequency with the maximum of the magnitude of the derivative of the torsion bar torque (M_DS).

5. The method as recited in claim 4, wherein the frequency is combined with the maximum of the magnitude of the derivative of the torsion bar torque (M_DS) by multiplying.

6. The method as recited in claim 4, wherein the frequencies of half-vibrations of the torsion bar are ascertained from in each case two adjacent zero crossings of the derivative of the torsion bar torque (M_DS).

7. The method as recited in claim 6, wherein the maximum of the magnitude of the derivative of the torsion bar torque (M_DS) between the adjacent zero crossings is determined.

8. The method as recited in claim 4, wherein the indicator (I) is formed from a first indicator component (I1), which is formed from the combination, in particular the multiplication, of the frequency with/by the maximum of the magnitude of the derivative of the torsion bar torque (M_DS), and from at least one second indicator component (I2) which is determined from the size of the magnitude of the derivative of the torsion bar torque (M_DS).

9. The method as recited in claim 8, wherein the two indicator components (I1, I2) are added in order to form the indicator (I).

10. The method as recited in claim 1, wherein the torsion bar torque (M_DS) is low-pass-filtered before the frequency and/or the amplitude are/is determined

11. The method as recited in claim 1, wherein the indicator (I) is post-processed, before being combined with the steering-stabilization function, by saturation and/or limitation and/or defining the minimum/maximum value.