Trailer curvature control and mode management with powertrain and brake support
A backup assist system for a vehicle reversing a trailer includes a brake module and a throttle module. The system further includes a controller having a vehicle speed detector and coupled with the brake module and the throttle module for implementing a backup mode including detecting an adverse operating condition and then adjusting at least one of the brake module and the throttle module and terminating the backup mode upon detecting the adverse operating condition for a time interval.
1. A backup assist system for a vehicle reversing a trailer, comprising:
a vehicle brake system;
a vehicle throttle;
a trailer angle sensor; and
a controller including a vehicle speed detector and coupled with the brake system and the throttle for:
implementing a backup mode including using a non-linear proportional-integral control scheme to control at least one of the brake system or the throttle to attempt to maintain a vehicle speed below a threshold speed; and
terminating the backup mode upon detecting that the vehicle speed is above the threshold speed for a time interval.
2. The system of claim 1 , wherein
controlling the brake system includes causing the brake system to increase a brake torque applied thereby according to the non-linear proportional-integral control scheme.
3. The system of claim 1 , wherein
controlling the throttle includes adjusting a position of the throttle to reduce an output thereof.
4. The system of claim 1 , wherein the threshold vehicle speed is a predetermined backup threshold speed.
5. The system of claim 1 , wherein:
the system further includes a trailer angle sensor; and
the controller adjusts the threshold vehicle speed downward in response to a detected threshold trailer angle based on input from the trailer angle sensor.
6. The system of claim 5 , wherein:
the system, while in the backup mode produces a driver warning in response to detection of the threshold trailer angle; and
the system further terminates the backup mode and presents a driver instruction upon detection of a maximum trailer angle that is greater than the threshold trailer angle.
7. The system of claim 1 , wherein during terminating of the backup mode, the controller ramps out the non-linear proportional-integral control scheme to control at least one of the brake system or the throttle.
8. The system of claim 1 , further including at least one object sensor associated with a side of the vehicle and coupled with the controller, wherein:
while in the backup mode, the controller adjusts the threshold vehicle speed downward upon detecting the trailer within a predetermined distance of the side of the vehicle.
9. A vehicle, comprising:
a steering system;
a vehicle speed detector;
a brake system;
a first controller 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; and
a second controller coupled with the speed detector and the brake system and implementing a non-linear proportional-integral control scheme to control the brake system to maintain a vehicle speed below a threshold speed.
10. The vehicle of claim 9 , wherein the second controller is coupled with the brake system outputs a brake torque demand to the brake system based on the proportional-integral control scheme.
11. The vehicle of claim 9 , wherein the first controller activates the second controller as a part of implementing the backup mode.
12. The vehicle of claim 11 , wherein the first controller further terminates the backup mode and deactivates the second controller upon detecting an adverse condition for a time interval.
13. The vehicle of claim 9 , wherein the proportional-integral control scheme uses a zero integral gain if the vehicle speed is below a reference speed that is less than the threshold speed.
14. The vehicle of claim 9 , wherein the proportional-integral control scheme uses an integral control according to the equation:
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15. A method for assisting reversing of a vehicle with a trailer, comprising:
implementing a backup control scheme to control a steering angle of a steering system to maintain the trailer along a user-selected reversing curvature path; and
using a non-linear proportional-integral control scheme to attempt to maintain a vehicle speed below a threshold speed; and
wherein the backup control scheme automatically terminates after a time interval of detecting that the vehicle speed is above the threshold speed.
16. The method of claim 15 , wherein attempting to maintain the speed of the vehicle below the threshold speed is achieved by the control scheme at least one of actuating a braking system of the vehicle or lowering a throttle output of the vehicle.
17. The method of claim 16 , further including, after the time interval of detecting that the vehicle speed is above the threshold speed, ramping out the non-linear proportional-integral control scheme.
18. The method of claim 15 , wherein the threshold vehicle speed is a predetermined backup threshold speed.
19. The method of claim 15 , wherein:
the threshold vehicle speed is derived by a comparison of the vehicle speed with a reference speed; and
the non-linear proportional-integral control scheme controls a brake system of the vehicle to maintain the vehicle speed within a predetermined range of the reference speed.