Trailer Articulation Angle Detection Using Variable Exposure Imaging
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Solution Overview
Problem
Existing trailer maneuvering assistants struggle to robustly and reliably determine the articulation angle, especially in poor visibility conditions due to the limitations of edge detection methods when cast shadows are present in images.
Innovation Solution
A method using a digital reversing camera with variable exposure times to record two images in the HSV color space, adjusting exposure to equalize brightness values between adjacent areas, allowing for improved edge detection by separating cast shadows from objects or edges, thereby enhancing the determination of the articulation angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If edge detection methods are used to determine the articulation angle, then the articulation angle can be determined, but the method does not work robustly and reliably when cast shadows are present in the image
Solution Approach 1:
The patent applies dynamics by making the exposure time variable and adaptive. The camera system dynamically adjusts exposure time based on detected shadow conditions in the image. When cast shadows are detected, the system changes the exposure time to compensate, allowing consistent edge detection of the drawbar regardless of shadow interference. This dynamic adaptation resolves the contradiction between maintaining reliable articulation angle determination and dealing with harmful cast shadows.
2Reliability
If a single exposure time is used for image recording, then the device complexity is low, but the edge detection fails in varying lighting conditions
Solution Approach 1:
The patent applies parameter changes by modifying the exposure time parameter of the camera based on lighting conditions. Instead of using a fixed exposure time, the system varies this parameter adaptively - using longer exposure times when shadows are present and shorter times in uniform lighting. This parameter adjustment enables reliable edge detection across varying lighting conditions without requiring fundamentally different hardware, thus improving reliability while keeping device complexity manageable.
3Measurement precision
If multiple images with different exposure times are recorded, then the separation of cast shadows from objects is improved, but the loss of time increases
Solution Approach 1:
The patent applies preliminary action by first capturing an initial image to detect the presence of cast shadows, then adjusting exposure time and capturing a second image only when shadows are detected. This conditional approach performs the additional image acquisition action in advance only when necessary, rather than always taking multiple images. This resolves the contradiction by achieving high measurement precision when needed while minimizing time loss in normal conditions.
Data Source
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AI summary
The invention relates to a method and to a device for determining the articulation angle of a combination, consisting of a towing vehicle and a trailer attached by means of a tongue, by identifying the hitch tongue by means of a digital back-up camera with variable exposure times, the following steps being carried out: a) recording a first color image of the rear environment of the towing vehicle, the color image being based on the HSV color space, b) examining the hue values (H), saturation values (S) and brightness values (V) of adjacent surfaces of a vehicle-environment region that is to be evaluated, c) determining the tongue from the first color image by means of an edge detection method in order to determine the articulation angle if the hue values (H), saturation values (S) and brightness values (V) of adjacent surfaces in the region that is to be evaluated are substantially equal, "substantially equal" meaning that the values of hue, saturation and brightness of adjacent surfaces differ by at most a first threshold in percent, d) recording a second color image in the HSV color space if in the first color image the hue values (H) and saturation values (S) of adjacent surfaces in the region that is to be evaluated are substantially equal while the brightness values (V) of the adjacent surfaces deviate greatly from each other, "deviate greatly from each other" meaning that the brightness values (V) of adjacent surfaces differ from each other by more than a second threshold in percent, the exposure time of the second color image being selected in such a way that the brightness values (V) of the adjacent surfaces within the vehicle-environment region that is to be evaluated are substantially equal, e) determining the tongue from the second color image by means of an edge detection method in order to determine the articulation angle.