Camera-Based Hitch Angle Detection for Drawbar Shape Variability
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Solution Overview
Problem
Existing hitch angle detection systems for trailers face challenges in accurately detecting the hitch angle regardless of the drawbar shape and require special equipment, which complicates the setup and reduces versatility.
Innovation Solution
A hitch angle detection system using a camera on the tractor to capture images of the trailer and tractor, calculating the left-right direction of both based on reflected edges or markers, allowing for hitch angle calculation without the need for additional special equipment, and enabling detection regardless of the drawbar shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a camera is used to detect hitch angle by recognizing a straight line of the drawbar, then the detection can be performed without special equipment like laser range finders, but the detection fails when the drawbar has non-straight shapes such as Y-letter shape
Solution Approach 1:
The patent segments the drawbar into multiple line segments instead of treating it as a single straight line. The drawbar recognition unit divides the detected drawbar into a plurality of line segments, which allows the system to handle various drawbar shapes (straight, Y-letter, etc.) by combining multiple segments to represent the complete drawbar geometry, thereby maintaining detection accuracy across different shapes.
2Measurement precision
If a laser range finder is used to measure distances for hitch angle calculation, then the hitch angle can be detected with high precision, but special equipment must be furnished and calibrated separately, increasing system complexity
Solution Approach 1:
The patent uses a camera that serves multiple functions: it captures images for both rear view confirmation during reversing and hitch angle detection. This eliminates the need for separate specialized equipment like laser range finders, reducing system complexity while maintaining the ability to perform both functions with a single device.
Solution Approach 2:
The patent replaces the mechanical/optical measurement system (laser range finder) with an image processing system based on computer vision. Instead of using physical distance measurement, the system calculates hitch angle by analyzing the geometric relationship between the tractor and trailer in the captured image, substituting mechanical measurement with optical-digital processing.
3Measurement precision
If a marker is pasted on the upper surface of the drawbar for detection, then the hitch angle can be detected using image processing, but the method is not applicable when the drawbar shape or surface is unsuitable for marker placement
Solution Approach 1:
The patent extracts and removes the marker from the system, making marker placement unnecessary. Instead of requiring markers on the drawbar, the system directly detects and recognizes the drawbar itself through image processing, extracting geometric information from the drawbar's visual appearance without any additional markers, thereby enabling universal application across all drawbar shapes and surfaces.
Data Source
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AI summary
A hitch angle detection system to detect a trailer hitch angle with a simple, versatile configuration is provided. Edge detection is performed in a portion including an image of a rear bumper of a tractor and an image of a front bumper of a trailer, the portion being included in an image captured by a rear camera, to extract an edge of the tractor rear bumper image and an edge of the trailer front bumper image. A straight line with which the edge of the rear bumper image is best approximated is calculated as a straight line parallel with the tractor left-right direction. A straight line with which the edge of the trailer front bumper image is best approximated is calculated as a straight line parallel with the trailer left-right direction. The relative angle of the straight line to the straight line is calculated as the trailer hitch angle.