ACTIVE SHIMMY MITIGATION

• US 20120041660A1
• Filed: 08/16/2010
• Published: 02/16/2012
• Est. Priority Date: 08/16/2010
• Status: Active Grant

• Current Assignee: FCA US LLC (Stellantis NV)
• Original Assignee: FCA US LLC (Stellantis NV)
• Inventors: Trotter, Loren M., Killian, Douglas W., French, Amanda J.
• Granted Patent: US 8,831,854 B2
• Time in Patent Office: Days
• US Class Current: 701/70
• CPC Class Codes: B60T 8/173 Eliminating or reducing the effect of unwanted signals, e.g. due to vibrations or electrical noise
• CPC Class Codes: B60T 8/17555 specially adapted for enhancing driver or passenger comfort, e.g. soft intervention or pre-actuation strategies

Abstract

A system mitigates shimmy of a wheel of a vehicle. The wheel is rotatable about an axis and is steerable by varying a steering angle of the wheel about a steering axis. The system includes a shimmy detection device that detects whether an oscillation/shimmy of the steering angle of the wheel occurs. The system also includes a brake that applies a braking load to decelerate rotation of the wheel about the axis. Furthermore, the system includes a controller that controls the brake to selectively apply the braking load to reduce the oscillation/shimmy of the steering angle of the wheel.

Claims

1. A system for mitigating shimmy of a wheel of a vehicle, the wheel being rotatable about an axis, the wheel being steerable by varying a steering angle of the wheel about a steering axis, the system comprising:

a shimmy detection device that detects whether an oscillation/shimmy of the steering angle of the wheel occurs;

a brake that applies a braking load to decelerate rotation of the wheel about the axis; and

a controller that controls the brake to selectively apply the braking load to reduce the oscillation/shimmy of the steering angle of the wheel.

2. The system of claim 1, wherein the shimmy detection device includes a steering wheel angle sensor that detects the steering angle of the wheel relative to a reference.

3. The system of claim 1, wherein the oscillation/shimmy causes turning of the wheel about the steering axis in a first direction, and wherein the controller controls the brake such that selective application of the braking load by the brake biases the wheel for turning about the steering axis in a second direction, the second direction being opposite the first direction.

4. The system of claim 3, wherein the shimmy detection device detects a magnitude of the steering angle of the wheel, and wherein the controller controls the brake such that selective application of the braking load biases the wheel for turning at a target steering angle having a target magnitude, the target magnitude substantially equal to negative one (−

1) times the detected magnitude of the steering angle.

5. The system of claim 1, wherein the controller outputs a first signal that causes the brake to selectively apply a first braking load, wherein the shimmy detection device detects whether the first braking load increases an amplitude of the oscillation/shimmy of the steering angle, and wherein the controller outputs a second signal that causes the brake to selectively apply a second braking load if the amplitude of the oscillation/shimmy increases, the second braking load being different from the first braking load.

6. The system of claim 1, wherein the oscillation/shimmy of the steering angle of the wheel is a substantially sinusoidal oscillation detected by the shimmy detection device.

7. The system of claim 1, further comprising a first wheel and a second wheel that are cooperatively steerable to steer the vehicle, a first brake that selectively applies a respective braking load to the first wheel, a second brake that selectively applies a respective braking load to the second wheel, and a processor that determines which of the first and second brakes to apply the respective braking load to reduce the oscillation/shimmy.

8. The system of claim 7, wherein the controller outputs a control signal to alternatingly apply the respective braking load to the first and second brakes.

9. The system of claim 7, wherein the controller outputs a control signal to apply only one of the respective braking load to the first and second brakes.

10. The system of claim 1, further comprising a memory device that stores data corresponding to the oscillation/shimmy, further comprising a sensor that detects a characteristic of the vehicle, and wherein the controller learns a target braking signal for reducing the oscillation/shimmy based on the data stored in the memory device and based on the detected characteristic of the vehicle.

11. A method of reducing shimmy of a wheel of a vehicle, the wheel being rotatable about an axis, the wheel being steerable by varying a steering angle of the wheel about a steering axis, the method comprising:

detecting an oscillation/shimmy of the steering angle of the wheel; and

selectively applying a braking load to decelerate rotation of the wheel about the axis and to reduce the oscillation/shimmy of the steering angle of the wheel.

12. The method of claim 11, further comprising determining a time interval for applying the braking load necessary for reducing the oscillation/shimmy, and wherein selectively applying the braking load includes selectively applying the braking load approximately during the time interval.

13. The method of claim 11, further comprising determining a target magnitude of the braking load for reducing the oscillation/shimmy, and wherein selectively applying the braking load includes selectively applying the braking load approximately equal to the target magnitude.

14. The method of claim 11, wherein detecting the oscillation/shimmy includes detecting turning of the wheel in a first direction, and wherein selectively applying the braking load includes selectively applying the braking load to bias turning of the wheel in a second direction that is opposite the first direction.

15. The method of claim 11, further comprising:

determining a target time interval for applying the braking load and determining a target magnitude of the braking load for reducing the oscillation/shimmy; and

determining if the target magnitude is greater than a predetermined braking limit of the wheel, and

wherein selectively applying the braking load includes selectively applying the braking load during an actual time interval and at an actual magnitude, wherein the actual time interval is greater than the target time interval, and wherein the actual magnitude is less than the target magnitude.

16. The method of claim 11, further comprising outputting a first signal to selectively apply a first braking load, detecting whether the first braking load increases an amplitude of the oscillation/shimmy of the steering angle, and outputting a second signal to selectively apply a second braking load to reduce the increased amplitude of the oscillation/shimmy, the corrective signal being different from the initial signal.

17. The method of claim 11, wherein the vehicle includes a first wheel and a second wheel that are cooperatively steerable to steer the vehicle, wherein the first wheel includes a first brake, and wherein the second wheel includes a second brake, and further comprising determining which of the first and second brakes to selectively apply the respective braking load to reduce the oscillation/shimmy.

18. The method of claim 17, wherein selectively applying the braking load includes alternatingly applying the respective braking load to the first and second brakes.

19. The method of claim 17, wherein selectively applying the braking load includes applying only one of the respective braking load to the first and second brakes.

20. The method of claim 11, further comprising outputting an alarm signal to indicate the oscillation/shimmy of the steering angle of the wheel.