Trailer articulation angle estimation
This invention takes the advantage of existing radar, vision and ultrasonic sensors available for side blind spot detection, rear view, rear virtual bumper, and rear parking assist. Using a sensor fusion technique to combine the useful information from these sensors, the trailer articulation angles as well as trailer track width and tongue length is accurately estimated. When an active steering system is present, vehicle and trailer can be controlled with increased stability by applying the trailer information.
1. A process for calculating a trailer hitch articulation angle in a combination comprising a motorized vehicle having a trailer comprising a wheeled axle that is pivotally-connected thereto, said motorized vehicle including at least one non-contacting sensor comprising a camera, said process comprising:
acquiring trailer position and range information including an azimuth angle between a center of the camera on said vehicle and a wheel on said wheeled axle of said trailer from said camera;
conveying said information to a microprocessor;
determining a trailer tongue length of said trailer from the trailer position and range information acquired from said camera;
determining a track width of said trailer from the trailer position and range information acquired from said camera; and
calculating a trailer hitch articulation angle of said trailer based on the determined trailer tongue length and the determined track width of said trailer.
2. The process of claim 1 , wherein calculating the trailer hitch articulation angle of said trailer based on the determined trailer tongue length and the determined track width of said trailer includes calculating the trailer hitch articulation angle of said trailer in accordance with the following relationship:
θ
=
sin
-
1
[
T
m
+
(
L
1
-
m
+
h
)
tan
φ
t
(
T
t
-
L
t
tan
φ
t
)
2
+
(
L
t
+
T
t
tan
φ
t
)
2
]
-
δ
t
wherein
θ is the trailer hitch articulation angle,
L 1 comprises a wheelbase of the motorized vehicle,
m is a distance between a center of rotation of a front left wheel of the motorized vehicle and a center of the camera,
h is a distance from a rear axle of the motorized vehicle to a pivotal coupling pivotally connecting the motorized vehicle and the trailer,
L t is the trailer tongue length of said trailer,
T t is one-half of the track width of said trailer,
T m is the distance from the centerline of the motorized vehicle to the center of the camera,
φt is the azimuth angle between the center of the camera on said vehicle and the wheel on the wheeled axle said trailer, and
δ
t
=
sin
-
1
[
T
t
+
L
1
tan
φ
t
(
T
t
-
L
t
tan
φ
t
)
2
+
(
L
t
+
T
t
tan
φ
t
)
2
]
.
3. A process for calculating a trailer hitch articulation angle in a combination comprising a motorized vehicle having a trailer comprising a wheeled axle that is pivotally-connected thereto, said motorized vehicle including at least one non-contacting sensor comprising a camera having a lens, said process comprising:
acquiring trailer position and range information including an angle between a point at which a wheel of the trailer contacts a road surface upon which the trailer resides and a horizontal line disposed substantially parallel to the road surface, which horizontal line intersects the lens of said camera;
conveying said information to a microprocessor;
determining a trailer tongue length of said trailer from the trailer position and range information acquired from said camera;
determining a track width of said trailer from the trailer position and range information acquired from said camera; and
calculating a trailer hitch articulation angle of said trailer based on the determined trailer tongue length and the determined track width.