OFFSET COMPENSATION FOR TRAILER BACKUP ASSIST STEERING INPUT DEVICE

• US 20140343795A1
• Filed: 07/30/2014
• Published: 11/20/2014
• Est. Priority Date: 04/19/2011
• 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
• Granted Patent: US 9,517,794 B2
• Time in Patent Office: Days
• US Class Current: 701/42
• CPC Class Codes: B60K 2360/126 Rotatable input devices for instruments
• CPC Class Codes: B60K 35/10 Input arrangements, i.e. from user to vehicle, associated with vehicle functions or specially adapted therefor
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 10/20 including control of steering systems
• CPC Class Codes: B60W 2300/14 Tractor-trailers, i.e. combinations of a towing vehicle and one or more towed vehicles, e.g. caravans; Road trains
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/22 Articulation angle, e.g. between tractor and trailer
• CPC Class Codes: B60W 2540/18 Steering angle
• CPC Class Codes: B60W 2540/215 Selection or confirmation of options
• CPC Class Codes: B60W 2720/22 Articulation angle, e.g. between tractor and trailer
• CPC Class Codes: B60W 30/18036 Reversing
• CPC Class Codes: B62D 13/06 for backing a normally drawn trailer
• CPC Class Codes: B62D 15/027 Parking aids, e.g. instruction means

Abstract

A trailer backup assist system for a vehicle reversing a trailer, according to one embodiment, includes a sensor that senses a hitch angle between the vehicle and the trailer. The trailer backup assist system may also include a steering input device, such as a rotatable knob, that is movable between a plurality of positions that each provide a desired curvature of the trailer. In addition, the trailer backup assist system may include a controller that determines an offset of the desired curvature when the knob is stationary in a central position. The control then generates a steering command for the vehicle to guide the trailer on the desired curvature, taking into consideration the offset.

Claims

1. A trailer backup assist system for a vehicle reversing a trailer, comprising:

a knob rotatable to positions each outputting a desired curvature; and

a controller determining an offset of the desired curvature when the knob is stationary in a central position and generating a steering command for the vehicle to guide the trailer on the desired curvature considering the offset.

2. The trailer backup assist system of claim 1, wherein the knob is spring biased to the central position and rotatable in opposing first and second directions therefrom to provide clockwise curvature values in the first direction and counterclockwise curvature values in the second direction.

3. The trailer backup assist system of claim 1, wherein the knob is spring biased to the central position, which is configured to provide a zero value for the desired curvature for backing the trailer along a substantially straight trajectory.

4. The trailer backup assist system of claim 1, wherein the offset provides a steering command for the vehicle to back the trailer along a substantially straight trajectory when the knob is in the central position.

5. The trailer backup assist system of claim 1, wherein a rate of rotation of the knob is substantially zero when the knob is stationary.

6. The trailer backup assist system of claim 1, further comprising:

a torque sensor coupled with the knob, wherein the controller determines the knob is in the central position for determining the offset when the torque sensor senses substantially no external torque on the knob and a rate of rotation of the knob is substantially zero.

7. A trailer backup assist system for a vehicle reversing a trailer, comprising:

a steering input device movable between positions that each provide a desired curvature for the trailer; and

a controller, comprising;

a compensation module determining an offset between zero and the desired curvature when the steering input device is stationary in a central position; and

a steering module for generating a steering command for the vehicle to guide the trailer on the desired curvature less the offset.

8. The trailer backup assist system of claim 7, wherein the steering input device includes a knob that is spring biased to the central position and rotatable in opposing directions therefrom.

9. The trailer backup assist system of claim 8, wherein the opposing directions of rotating the knob provide clockwise curvature values in a first direction and counterclockwise curvature values in a second direction

10. The trailer backup assist system of claim 7, wherein the steering input device includes a knob is spring biased to the central position, which is configured to provide a zero value for the desired curvature for backing the trailer along a substantially straight trajectory.

11. The trailer backup assist system of claim 7, wherein the offset provides a steering command for the vehicle to back the trailer along a substantially straight trajectory when the steering input device is in the central position.

12. The trailer backup assist system of claim 7, wherein a rate of movement of the steering input device is substantially zero when the steering input device is stationary.

13. The trailer backup assist system of claim 7, further comprising:

a sensor coupled with the steering input device, wherein the controller determines the steering input device is in the central position for determining the offset when the sensor senses substantially no external force on the steering input device and substantially no movement.

14. A method for autonomously steering a vehicle reversing a trailer, comprising:

providing a knob rotatable in opposing directions from a central position to a plurality of positions, each defining a desired curvature;

determining an offset of the desired curvature when the knob is stationary in the central position; and

generating a steering command for the vehicle to guide the trailer on the desired curvature considering the offset.

15. The method of claim 14, wherein the plurality of positions of the knob provide clockwise curvature values in a first rotational direction from the central position and counterclockwise curvature values in a second rotational direction from the central position.

16. The method of claim 14, wherein the offset configures the steering command for the vehicle to back the trailer along a substantially straight trajectory when the knob is in the central position.

17. The method of claim 14, further comprising:

sensing a rate of rotation of the knob, such that the rate of rotation is substantially zero when the knob is stationary and the offset is determined.

18. The method of claim 14, further comprising:

sensing a hitch angle between the vehicle and the, wherein the steering command is generated based on the hitch angle.

19. The method of claim 18, wherein the knob is rotatable in opposing directions from the central position to opposing rotational end positions, whereby the central position defines the desired curvature as zero and the opposing rotational end positions are defined by a radius of curvature controllable for the trailer without the hitch angle exceeding a jackknife threshold that is determined based on a length of the trailer and a wheelbase of the vehicle.

20. The method of claim 14, further comprising:

biasing the knob to the central position with a spring; and

sensing torque on the knob, such that the knob is determined to be in the central position when no external torque is sensed on the knob.