Fifth-Wheel Trailer Angle Detection Using Bird's-Eye Hough Transform
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Solution Overview
Problem
Existing vehicular trailer assist systems face challenges in accurately determining the angle of nonconventional trailers like gooseneck and fifth wheel campers, which are complex due to their size, weight, and three degrees of freedom, making maneuverability difficult and dangerous, especially during reverse operations.
Innovation Solution
A vehicular trailer assist system utilizing a rearward viewing camera with a CMOS imaging array and an electronic control unit that processes fisheye-view frames to transform them into bird's-eye view, applying a Hough transform to determine the trailer angle by identifying features and tracking changes in the trailer's position relative to the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a rearward viewing camera with fisheye lens is used to capture wide-angle images for trailer angle detection, then the field of view is improved to cover the entire trailer and vehicle area, but the image distortion increases making angle measurement more difficult
Solution Approach 1:
The patent transforms the distorted 2D fisheye image coordinates into a corrected coordinate system that represents the actual 3D spatial relationships. The image processor applies a fisheye correction algorithm that maps pixels from the curved fisheye projection to a flattened, geometrically accurate representation, enabling precise angle measurement while preserving the wide field of view capability
Solution Approach 2:
The system changes the parameter representation of image coordinates by applying a mathematical transformation model specific to the fisheye lens characteristics. By calibrating the lens distortion parameters and applying inverse distortion correction, the system converts distorted image coordinates into undistorted coordinates that accurately reflect real-world geometry for angle calculation
2Adaptability or versatility
If the system supports various trailer types, heights, and hitch configurations including angles up to 90 degrees, then the adaptability is improved, but the device complexity increases due to multiple detection scenarios
Solution Approach 1:
The patent implements a universal detection algorithm that automatically adapts to different trailer types, hitch configurations, and angles. The image processor identifies key geometric features (vehicle rear bumper, trailer hitch, trailer body) and calculates angles using a unified mathematical approach that works for conventional trailers, gooseneck trailers, fifth wheel campers, and angles ranging from 0 to 90 degrees, eliminating the need for separate detection systems for each trailer type
Solution Approach 2:
The system employs dynamic parameter adjustment where the detection algorithm automatically adapts its parameters based on the detected trailer configuration. The image processor identifies the trailer type and hitch position, then dynamically adjusts the region of interest, angle calculation methodology, and reference frames to optimize detection accuracy for each specific scenario without requiring manual configuration
3Measurement precision
If image processing is performed to transform fisheye-view frames into bird's-eye view frames and determine trailer angle, then the measurement precision is improved, but the loss of time increases due to complex processing operations
Solution Approach 1:
The system performs preliminary calibration of the fisheye lens distortion parameters during system setup or manufacturing, storing the correction transformation matrix in memory. During actual trailer angle detection, the pre-calibrated transformation parameters are applied directly to the captured images, eliminating the need for real-time calibration calculations and significantly reducing processing time while maintaining high measurement precision
4Manufacturing precision
If a CMOS imaging array with at least one million photosensors is used, then the manufacturing precision is improved for capturing detailed image data, but the weight of the camera system increases
Solution Approach 1:
The patent replaces heavy mechanical lens systems with complex optical assemblies by using a CMOS image sensor with integrated lens and advanced digital image processing algorithms. The high-resolution CMOS array with one million or more photosensors captures sufficient detail, and the fisheye correction algorithm compensates for the simplified optical design, achieving high manufacturing precision while minimizing camera weight through electronic rather than mechanical solutions
Data Source
AI summary
A vehicular trailer assist system includes a rearward viewing camera disposed at a vehicle that views a trailer hitched at a fifth wheel hitch at a bed of the vehicle. With the trailer hitched to the fifth wheel hitch at the bed of the vehicle, the vehicular trailer assist system, via processing fisheye-view frames of image data captured by the camera, transforms fisheye-view frames of image data captured by the rearward viewing camera into bird's-eye view frames of image data. The vehicular trailer assist system determines a region of interest (ROI) in a transformed bird's-eye view frames of image data that includes a region where the fifth wheel hitch is present. The vehicular trailer assist system, via a Hough transform that transforms the determined ROI from a Cartesian coordinate system to a polar coordinate system, determines a trailer angle of the trailer relative to the vehicle.