Trailer length estimation in hitch angle applications
A vehicle system for estimating a trailer length is disclosed. The system incorporates at least one sensor configured to measure a wheel steer angle and a trailer angle in communication with a processor. The processor is operable to determine a first length by a first computation method and determine a second length by a second computation method. The processor is further operable to validate an estimated trailer length based on the first length and the second length and perform a back-up function for the trailer based on the estimated trailer length.
1. An apparatus for determining an estimated trailer length comprising:
a processor operable to:
determine a first trailer length using an angle from a hitch angle sensor;
determine a second trailer length using the angle;
determine a difference between the first trailer length and the second trailer length as a result in a first comparison; and
set the estimated trailer length to the first trailer length based on the result being less than a first predetermined value.
2. The apparatus according to claim 1 , wherein the processor is further operable to:
compare the second trailer length to a second predetermined value in a second comparison to determine if the second trailer length is greater than the second predetermined value.
3. The apparatus according to claim 2 , wherein the estimated trailer length is set to the second trailer length in response to the second comparison to validate the estimated trailer length yielding that the second trailer length is greater than the second predetermined value.
4. The apparatus according to claim 1 , wherein the first comparison of the first trailer length and the second trailer length comprises determining the result as an absolute value of the difference between the first trailer length and the second trailer length.
5. The apparatus according to claim 1 , wherein the processor is further operable to:
receive measurements of a wheel steer angle.
6. The apparatus according to claim 5 , wherein the processor is further operable to:
receive measurements of a trailer angle.
7. The apparatus according to claim 6 , wherein the first trailer length is calculated based on the wheel steer angle and a minimum error of the trailer angle with respect to time.
8. A method for determining an estimated trailer length comprising:
receiving a steering angle from a steering module;
receiving a trailer angle from a hitch sensor;
calculating a first trailer length based on the steering angle and a minimum error calculation of the trailer angle;
calculating a second trailer length based on a radius of curvature of a trailer and a vehicle;
and evaluating the first trailer length and the second trailer length to determine the estimated trailer length, wherein the evaluating of the first trailer length and the second trailer length comprises:
determining a difference between the first trailer length and the second trailer length; and
comparing the difference to a first predetermined threshold to determine a first validation of the estimated trailer length.
9. The method according to claim 8 , wherein the radius of curvature is calculated based on the steering angle and the trailer angle.
10. The method according to claim 8 , wherein the first trailer length and the second trailer length are determined a plurality of times to improve the estimated trailer length over time.
11. The method according to claim 8 , wherein the evaluating of the first trailer length and the second trailer length further comprises:
comparing the second trailer length to a second predetermined threshold to determine a second validation of the estimated trailer length.
12. The method according to claim 11 , wherein the estimated trailer length is utilized for a vehicle trailer back-up assist function in response to the comparisons to the first predetermined threshold and the second predetermined threshold.
13. A vehicle system for estimating a trailer length comprising:
at least one sensor configured to measure a wheel steer angle and a trailer angle; and
a processor operable to:
determine a first trailer length by a first computation method;
determine a second trailer length by a second computation method; and
validate an estimated trailer length based on the first trailer length and the second trailer length, wherein the validation of the estimated trailer length comprises a comparison of the difference of the first trailer length and the second trailer length to a predetermined value; and
perform a back-up function for the trailer based on the estimated trailer length.
14. The vehicle system according to claim 13 , wherein the first computation method comprises calculating a mean squared error of a rate of change of the trailer angle.
15. The vehicle system according to claim 13 , wherein the second computation method comprises calculating a radius of curvature based on the wheel steer angle and the trailer angle.
16. The vehicle system according to claim 15 , wherein the radius of curvature is calculated about a center of rotation of a vehicle in which the vehicle system is implemented.