Speed limiting comfort enhancement

Patent metadata

Field	Value
Publication number	US-9676377-B2
Application number	US-201514741614-A
Country	US
Kind code	B2
Filing date	Jun 17, 2015
Priority date	Jun 17, 2015
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A vehicle includes a steering system, a vehicle speed detector, a brake system, and a control system. The control system is coupled with steering system for implementing a backup mode for reversing a trailer including controlling the steering system to maintain the trailer along a path. The control system is further coupled with the speed detector and the brake system and selectively outputs a rate-limited brake torque demand to the brake system to maintain a vehicle speed below a threshold speed.

First claim

What is claimed is:

1. A vehicle, comprising:
a vehicle speed detector detecting a vehicle speed;
a brake system; and
a control system:
implementing a control mode including determining a threshold speed;
monitoring the vehicle speed and implementing a control scheme to derive and output an initial brake torque demand to maintain the vehicle speed below the threshold speed; and
applying a rate-limit operator to the initial brake torque demand to derive a rate-limited brake torque demand for output to the brake system.

2. The vehicle of claim 1 , further comprising a steering system, wherein:
the control mode is a backup mode for reversing a trailer further including controlling the steering system to maintain the trailer along a path.

3. The vehicle of claim 1 , wherein the control system includes:
a first controller coupled with the steering system and implementing the backup mode; and
a second controller coupled with the speed detector and the brake system and implementing the control scheme to derive and output the rate-limited brake torque demand to the brake system to maintain the vehicle speed below the threshold speed.

4. The vehicle of claim 3 , wherein the second controller is a proportional-integral controller implementing the control scheme to derive and output the initial brake torque demand.

5. The vehicle of claim 3 , wherein the control scheme is non-linear and uses a zero integral gain if the vehicle speed is below a reference speed that is less than the threshold speed.

6. The vehicle of claim 1 , wherein the rate-limiting operator reduces a ramp up rate of the rate-limited brake torque demand compared to a ramp up rate of the initial brake torque demand.

7. The vehicle of claim 1 , wherein the control system further adjusts the rate-limiting operator on receipt of a selection of a comfort mode.

8. The vehicle of claim 7 , wherein:
the control scheme is a proportional-integral control scheme; and
the control system further adjusts at least one of a proportional gain and an integral gain of the proportional-integral control scheme based on receipt of the selection of the comfort mode.

9. A backup assist system for a vehicle reversing a trailer, comprising:
a steering module;
a brake module;
a vehicle speed detector detecting a vehicle speed; and
a controller:
implementing a backup mode including providing an output to the steering module to maintain the trailer along a path; and
attempting to maintain the vehicle speed below a threshold speed, derived using a parameter of the backup mode, by selectively outputting a rate-limited brake torque demand to the brake module.

10. The system of claim 9 , wherein the controller:
includes a vehicle speed detector;
receives a vehicle speed signal from the vehicle speed detector; and
derives the rate-limited brake torque demand using:
a proportional-integral control scheme with the threshold speed and the vehicle speed signal as inputs and an initial brake torque as an output; and
a rate limiting operator with the initial brake torque as an input and the rate-limited brake torque as an output.

11. The system of claim 10 , wherein the rate limiting operator reduces a ramp up rate of the initial brake torque demand.

12. The system of claim 10 , wherein the controller further filters the threshold speed into the proportional-integral controller.

13. The system of claim 10 , wherein the controller adjusts the rate limiting operator on receipt of a selection of a comfort mode.

14. A method for assisting reversing of a vehicle with a trailer, comprising:
controlling a steering angle of a vehicle steering system to maintain the trailer along a user-selected reversing curvature path;
monitoring a speed of the vehicle; and
attempting to maintain a vehicle speed below a threshold speed, derived based on a parameter used in controlling the steering angle, by selectively outputting a rate-limited brake torque demand to a brake module of the vehicle.

15. The method of claim 14 , wherein the rate-limited brake torque demand is derived using:
a proportional-integral control scheme with the threshold speed and the vehicle speed as inputs and an initial brake torque as an output; and
a rate limiting operator with the initial brake torque as an input and the rate-limited brake torque as an output.

16. The method of claim 15 , further including adjusting the rate limiting operator on receipt of a selection of a comfort mode.

Assignees

• Ford Global Tech Llc

Inventors

• Hafner Michael
• Lavoie Erick Michael

Classifications

• B60T8/1708 Primary

  for lorries or tractor-trailer combinations · CPC title

• B62D15/0285

  Parking performed automatically · CPC title

• B60D1/36

  for facilitating connection, e.g. hitch catchers · CPC title

• B62D13/06

  for backing a normally drawn trailer · CPC title

• B60T8/323

  Systems specially adapted for tractor-trailer combinations · CPC title