Trailer tongue length estimation using a hitch angle sensor

• US 20040130441A1
• Filed: 01/03/2003
• Published: 07/08/2004
• Est. Priority Date: 01/03/2003
• Status: Active Grant

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Deng, Weiwen, Lee, Yong Han
• Granted Patent: US 6,806,809 B2
• Time in Patent Office: Days
• US Class Current: 340/431
• CPC Class Codes: B60D 1/58 Auxiliary devices

Abstract

A control system for estimating the tongue length of a trailer being towed by a vehicle in connection with a front wheel steering with or without a coordinated rear wheel steering associated with the vehicle. The control signal system employs an algorithm that calculates an estimated hitch angle between the vehicle and the trailer based on an estimated tongue length, a front wheel steering angle, a rear wheel steering angle, a measured hitch angle, vehicle speed and vehicle yaw rate. The estimated hitch angle is compared to the measured hitch angle to generate a hitch angle error that is converted to a tongue length error. The tongue length error is compared to the estimated tongue length to become a corrected estimated tongue length for a next computation period. After a few seconds of processing, the corrected estimated tongue length will be the actual tongue length of the trailer.

Claims

1. A system for estimating a tongue length of a trailer being towed by a vehicle, said vehicle including a pair of front wheels and a pair of rear wheels, said system comprising:

a front wheel angle sensor for providing a front wheel angle signal indicative of the angle of the front wheels of the vehicle;

a vehicle speed sensor for providing a vehicle speed signal indicative of the speed of the vehicle;

a vehicle yaw rate sensor for providing a yaw rate signal indicative of the yaw rate of the vehicle;

a hitch angle sensor for providing a measured hitch angle signal indicative of a hitch angle between the vehicle and the trailer; and

a tongue length estimation controller for computing the estimate of the tongue length, said estimation controller computing the estimate of the tongue length based on the front wheel angle signal, the vehicle yaw rate signal, the vehicle speed signal and the measured hitch angle signal.

2. The system according to claim 1 wherein the estimation controller computes an estimated hitch angle signal and compares the estimated hitch angle signal to the measured hitch angle signal to generate a hitch angle error signal therefrom.

3. The system according to claim 2 wherein the tongue length estimation controller converts the hitch angle error signal to a tongue length error signal.

4. The system according to claim 3 wherein the estimation controller includes a PID controller that is responsive to the hitch angle error signal, said PID controller converting the hitch angle error signal to the tongue length error signal.

5. The system according to claim 3 wherein the estimation controller includes a comparator for comparing the tongue length error signal to an initial tongue length estimation signal to generate a corrected tongue length estimation signal.

6. The system according to claim 5 wherein the corrected tongue length estimation signal becomes the estimate of the tongue length after a predetermined number of calculation periods.

7. The system according to claim 1 further comprising a rear wheel angle sensor for providing a rear wheel angle signal indicative of the angle of the rear wheels of the vehicle, said tongue length estimation controller computing the estimate of the tongue length of the trailer based on all of the front wheel angle signal, the rear wheel angle signal, the vehicle yaw rate signal, the vehicle speed signal and the measured hitch angle signal.

8. The system according to claim 7 wherein the rear wheels of the vehicle are automatically controlled by a rear wheel controller in the vehicle.

9. The system according to claim 1 wherein the tongue length estimation controller does not compute the estimate of the tongue length until certain initial conditions are met, said initial conditions including vehicle speed, vehicle yaw rate and the hitch angle.

10. The system according to claim 9 wherein the initial conditions include a vehicle speed greater than 1 kilometer per hour, a vehicle yaw rate greater than 0.1 degrees per second and a hitch angle greater than 5 °

.

11. The system according to claim 1 wherein the system is used in connection with a coordinated front and rear wheel steering system.

12. A system for estimating a tongue length of a trailer being towed by a vehicle, said vehicle including a pair of front wheels and a pair of rear wheels, where the front wheels are steered by an operator and the rear wheels are automatically steered by an on-board steering controller, said control system comprising:

a front wheel angle sensor for providing a front wheel angle signal indicative of the angle of the front wheels of the vehicle;

a rear wheel angle sensor for providing a rear wheel angle signal indicative of the angle of the rear wheels of the vehicle;

a vehicle speed sensor for providing a vehicle speed signal indicative of the speed of the vehicle;

a vehicle yaw rate sensor for providing a yaw rate signal indicative of the yaw rate of the vehicle;

a hitch angle sensor for providing a measured hitch angle signal indicative of a hitch angle between the vehicle and the trailer; and

a tongue length estimation controller for computing the estimate of the tongue length of the trailer, said estimation controller computing an estimated hitch angle signal based on the front wheel angle signal, the rear wheel angle signal, the vehicle yaw rate signal, the vehicle speed signal and the measured hitch angle signal, said tongue length estimation controller including a first comparator for comparing the estimated hitch angle signal to the measured hitch angle signal to generate a hitch angle error signal representative of the difference between the estimated hitch angle and the measured hitch angle, said estimation controller further including a PID controller that is responsive to the hitch angle error signal, said PID controller converting the hitch angle error signal to a tongue length error signal, said estimation controller further including a second comparator for comparing the tongue length error signal to an initial tongue length estimation signal to provide a corrected tongue length estimation signal, wherein the corrected tongue length estimation signal becomes the estimated tongue length after a predetermined number of calculation periods.

13. The system according to claim 12 wherein the tongue length estimation controller does not compute the estimate of the tongue length until certain initial conditions are met, said initial conditions including vehicle speed, vehicle yaw rate and the hitch angle.

14. The system according to claim 13 wherein the initial conditions include a vehicle speed greater than 1 kilometer per hour, a vehicle yaw rate greater than 0.1 degrees per second and a hitch angle greater than 5 °

.

15. A system comprising:

a vehicle including a pair of front wheels and a pair of rear wheels, said vehicle further including a vehicle hitch post;

a trailer including trailer wheels, said trailer further including a trailer hitch post;

a hitch coupling the vehicle hitch post to the trailer hitch post;

a hitch sensor for measuring a hitch angle between the vehicle hitch post and the trailer hitch post, said hitch sensor providing a hitch angle signal indicative of the measured hitch angle; and

a controller, said controller computing a tongue length of the trailer based on the hitch angle signal.

16. The system according to claim 15 wherein the controller compares the hitch angle signal to an estimated hitch angle, said estimated hitch angle being computed by an algorithm from inputs including the angle of the vehicle'"'"'s front wheels, the angle of the vehicle'"'"'s rear wheels, the yaw rate of the vehicle, the speed of the vehicle and the measured hitch angle.

17. The system according to claim 15 wherein the system is used in connection with a coordinated front and rear wheel steering system.

18. A method of estimating a tongue length of a trailer being towed by a vehicle, comprising:

determining the angle of front wheels of the vehicle;

determining the speed of the vehicle;

determining the yaw rate of the vehicle;

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

computing the estimate of the tongue length of the trailer based on the front wheel angle, the vehicle yaw rate, the vehicle speed and the hitch angle.

19. The method according to claim 18 further comprising determining the angle of rear wheels of the vehicle, wherein computing the tongue length includes computing the estimate of the tongue length based on the front wheel angle, the rear wheel angle, the vehicle yaw rate, the vehicle speed and the hitch angle.

20. The method according to claim 18 wherein computing the estimate of the tongue length includes computing an estimated hitch angle and comparing the estimated hitch angle to the measured hitch angle to generate a hitch angle error signal.

21. The method according to claim 20 wherein computing the estimate of the tongue length includes converting the hitch angle error signal to a tongue length error signal.

22. The method according to claim 21 wherein computing the estimate of the tongue length includes comparing the tongue length error signal to an initial tongue length estimation signal to generate a corrected tongue length estimation.