Speed control for motor vehicles

• US 10,611,407 B2
• Filed: 10/04/2016
• Issued: 04/07/2020
• Est. Priority Date: 10/19/2015
• 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, Mattern, Donald Jacob, Raad, Joseph M.
• Primary Examiner(s): Chace, Christian
• Assistant Examiner(s): Smith, Aaron C
• Application Number:
  US15/284,791
• Publication Number:
  US 20170106865A1
• Time in Patent Office: 1,281 Days
• 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 is provided herein. The trailer backup assist system includes a hitch angle sensor configured to determine a hitch angle between a vehicle and a trailer attached thereto. An input device is configured to accept an input command corresponding to a trailer path command curvature. A controller is configured to determine a vehicle threshold speed limit by determining a first vehicle speed limit based on the hitch angle and a second speed limit based on the command curvature. The controller generates a command to limit vehicle speed in a reverse direction below the threshold speed limit.

Claims

1. A trailer backup assist system, comprising:

a hitch angle sensor configured to determine a hitch angle between a vehicle and a trailer attached thereto;

an input device configured to accept an input command corresponding to a trailer path command curvature; and

a controller configured to determine a vehicle threshold speed limit by determining a first vehicle speed limit based on the hitch angle and a second vehicle speed limit based on the command curvature, wherein the controller generates a command to limit vehicle speed in a reverse direction below the threshold speed limit and the vehicle threshold speed limit is set to the higher of the first and second vehicle speed limits when a magnitude of an input command rate is decreasing and the vehicle threshold speed limit is set to the lower of the first and second vehicle speed limits when a magnitude of input command rate is increasing.

2. The trailer backup assist system of claim 1, wherein the command controls at least one of a brake system, an engine torque, and a transmission gear selection to thereby control the vehicle speed in the reverse direction.

3. The trailer backup assist system of claim 2, wherein the brake system is a vehicle brake system.

4. The trailer backup assist system of claim 1, wherein the vehicle threshold speed limit is the higher of the first and second vehicle speed limits when a magnitude of hitch angle rate is decreasing and the desired trailer path command curvature is less than an instantaneous trailer path curvature.

5. The trailer backup assist system of claim 1, wherein the input device includes a rotatable knob configured to be mounted in a vehicle interior.

6. A method of controlling the speed of a motor vehicle, the method comprising:

determining a hitch angle between a vehicle and a trailer attached to the vehicle;

determining a trailer curvature command based on an input device;

calculating a first vehicle speed limit based on the hitch angle;

calculating a second speed limit based on the trailer path curvature command;

determining a threshold speed limit based on the first and second speed limits; and

limiting the speed of the vehicle to the threshold speed, wherein a controller sets the vehicle threshold speed limit at the higher of the first and second speed limits when an absolute value of a hitch angle rate is decreasing and a trailer curvature command rate is also decreasing.

7. The method of claim 6, wherein a vehicle is maintained below the threshold speed limit by controlling at least one of a brake system, an engine torque, and a transmission gear selection to move the trailer along a desired trailer curvature path that is within an acceptable error criteria.

8. The method of claim 6, wherein the input device receives an input as an input magnitude that is correlated to a corresponding trailer curvature path based on values stored in a look-up table.

9. The method of claim 6, wherein the input device is biased towards a neutral position.