Handwheel obstruction detection and inertia compensation

• US 10,421,490 B2
• Filed: 05/15/2017
• Issued: 09/24/2019
• Est. Priority Date: 03/25/2015
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Lavoie, Erick Michael, Recker, Darrel Alan, Johnson, Michael Richard
• Primary Examiner(s): Black, Thomas G
• Assistant Examiner(s): Lewandroski, Sara J
• Application Number:
  US15/595,038
• Publication Number:
  US 20170247053A1
• Time in Patent Office: 862 Days
• CPC Class Codes: B62D 1/04 Hand wheels
• CPC Class Codes: B62D 13/06 for backing a normally drawn trailer
• CPC Class Codes: B62D 15/0285 Parking performed automatically
• CPC Class Codes: B62D 5/00 Power-assisted or power-driven steering for non-deflectable wheels B62D11/00; fluid-pressure servomotors in general F15B
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input
• CPC Class Codes: B62D 5/0481 monitoring the steering system, e.g. failures
• CPC Class Codes: B62D 6/10 characterised by means for sensing or determining torque

Abstract

A vehicle steering system includes a first sensor sensing a pinion angle of a handwheel and a second sensor sensing a torsion bar windup angle. An autonomous steering module generates a steering command having an input torque signal. A steering angle controller is configured to determine a filtered handwheel acceleration based on the pinion angle and the windup angle. The steering angle controller also determines an offset torque based on the filtered handwheel acceleration. Further, the steering angle controller applies the offset torque to the input torque signal to define a refined torque signal that compensates for inertia and off-center mass of the handwheel.

Claims

1. A vehicle steering system for a vehicle, comprising:

a sensor sensing a handwheel angle;

an autonomous steering module generating an input torque signal, wherein the autonomous steering module includes a trailer backup assist controller for generating a steering command for guiding a trailer connected to the vehicle in reverse, wherein the trailer backup assist controller receives a hitch angle between the trailer and the vehicle sensed by a hitch angle sensor and generates the steering command based on the sensed hitch angle to generate the input torque signal to steer the vehicle when the vehicle is driving in reverse; and

a steering angle controller for determining a handwheel acceleration based on the handwheel angle, determining an offset torque based on the handwheel acceleration, and generating a compensated torque signal based on the offset torque and the input torque signal.

2. The vehicle steering system of claim 1, wherein the sensor includes a first sensor sensing a pinion angle and a second sensor sensing a torsion bar windup angle, and wherein the handwheel angle is based on the pinion angle and the windup angle, and wherein the steering angle controller autonomously controls steering of the vehicle based on the compensated torque signal and stops autonomous steering of the vehicle when the compensated torque signal exceeds a torque threshold.

3. The vehicle steering system of claim 1, wherein the compensated torque signal is configured to compensate for inertia and off-center mass of a handwheel.

4. The vehicle steering system of claim 1, wherein the sensor includes a first sensor sensing a pinion angle and a second sensor sensing a torsion bar windup angle, and wherein the handwheel angle is based on the pinion angle and the windup angle, and wherein a high torque value associated with a sudden change in direction of the pinion angle is reduced in the compensated torque signal to prevent the compensated torque signal from errantly exceeding a torque threshold.

5. The vehicle steering system of claim 1, wherein the handwheel acceleration is filtered.

6. The vehicle steering system of claim 5, wherein the compensated torque signal is passed through a low-pass filter prior to operating the handwheel with the compensated torque signal, and wherein the handwheel acceleration is filtered with a high-pass filter.

7. A vehicle steering system for a vehicle, comprising:

a sensor sensing a handwheel angle;

a trailer backup assist controller for generating a steering command for guiding a trailer connected to the vehicle in reverse, the steering command generating an input torque signal, wherein the steering command is based on a hitch angle between the vehicle and trailer as sensed by a hitch angle sensor to generate the input torque signal to steer the vehicle when the vehicle is driving in reverse; and

a steering angle controller for determining a handwheel acceleration based on the handwheel angle, determining an offset torque based on the handwheel acceleration, and generating a compensated torque signal based on the offset torque and the input torque signal.

8. The vehicle steering system of claim 7, wherein the handwheel acceleration is filtered, and wherein the compensated torque signal is passed through a low-pass filter prior to operating the handwheel angle with the compensated torque signal, and wherein the handwheel acceleration is filtered with a high-pass filter.

9. The vehicle steering system of claim 7, wherein the sensor includes a first sensor sensing a pinion angle and a second sensor sensing a torsion bar windup angle, and wherein the handwheel angle is based on the pinion angle and the windup angle.

10. The vehicle steering system of claim 9, wherein a high torque value associated with a sudden change in direction of the pinion angle is reduced in the compensated torque signal to prevent the compensated torque signal from errantly exceeding a torque threshold.

11. The vehicle steering system of claim 7, wherein the steering angle controller autonomously controls steering of the vehicle based on the compensated torque signal and stops autonomous steering of the vehicle when the compensated torque signal exceeds a torque threshold.

12. A method for steering a vehicle connected to the trailer in reverse, comprising:

sensing an angle of a handwheel;

sensing a hitch angle between a trailer and the vehicle;

generating a steering command to steer the vehicle for guiding the trailer in reverse based on the sensed hitch angle, the steering command generating an input torque signal;

determining a handwheel acceleration based on the angle;

determining an offset torque based on the handwheel acceleration; and

generating a compensated torque signal based on the offset torque and the input torque signal to compensate for inertia and off-center mass of the handwheel.

13. The method of claim 12, wherein the compensated torque signal is passed through a low-pass, and wherein the handwheel acceleration is filtered with a high-pass filter.

14. The method of claim 13 further comprising:

autonomously operating a handwheel angle based on the filtered compensated torque signal and ceasing autonomous operation of the handwheel angle when the compensated torque signal exceeds a threshold torque.

15. The method of claim 12, further comprising:

autonomously operating the angle of the handwheel based on the compensated torque signal.

16. The method of claim 12, wherein sensing the angle of the handwheel includes sensing a pinion angle and sensing a torsion bar windup angle, and wherein the angle of the handwheel is based on the pinion angle combined with the torsion bar windup angle.

17. The method of claim 12, wherein a high torque value associated with a sudden change in direction of a pinion angle is reduced in the compensated torque signal to prevent the compensate torque signal from errantly exceeding a torque threshold.

18. The method of claim 14, wherein the threshold torque value is configured to be exceeded when an object is obstructing a predicted change to the handwheel angle.