Trailer Assist Camera Calibration for Hitch Point Detection
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Solution Overview
Problem
Existing vehicle vision systems struggle to accurately determine the location of a hitch ball and other trailer features, especially during calibration maneuvers, which is crucial for safe and efficient trailer handling.
Innovation Solution
A vehicle trailer assist system equipped with a rear-facing camera and an electronic control unit (ECU) that processes image data to determine the initial trailer template, detect the hitch ball, and calculate its location by matching image data edges with the template during a calibration maneuver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera and image processing system are used to detect trailer features, then the ability to determine hitch ball location is improved, but the complexity of the system increases
Solution Approach 1:
The system performs a calibration maneuver before normal operation to pre-determine the trailer template and hitch ball location. During calibration, the vehicle executes specific movements (straight line, turn, straight line) while the camera captures images that are processed to establish the trailer's geometric features and hitch ball position. This preliminary action stores the trailer template in memory for subsequent detection operations, eliminating the need for complex real-time calculations during normal trailering.
Solution Approach 2:
The system creates a digital copy (trailer template) of the physical trailer's geometric features through image processing during calibration. The template includes the trailer contour, hitch ball location, and other relevant features stored as image data edges. This copy is then used for comparison and detection during actual trailering operations, simplifying the detection process by referencing the pre-established template rather than performing full analysis on every frame.
2Measurement precision
If multiple frames of image data are captured and processed during calibration, then the accuracy of trailer feature detection is improved, but the time required for calibration increases
Solution Approach 1:
The calibration process is divided into distinct segments or maneuvers: a first straight-line movement, a turn, and a second straight-line movement. Each segment captures specific types of image data that contribute different information to the trailer template. This segmentation allows the system to efficiently collect necessary calibration data through structured movements rather than continuous random sampling, reducing overall calibration time while maintaining accuracy.
Solution Approach 2:
The calibration maneuver is designed as a continuous sequence of vehicle movements without interruption. The vehicle performs the calibration in one continuous operation (straight line → turn → straight line) while the camera continuously captures images throughout the maneuver. This continuous action ensures that all necessary trailer features are captured in a single calibrated sequence, eliminating the need for multiple separate calibration sessions and reducing total calibration time.
Data Source
AI summary
A vehicular trailer assist system includes a camera disposed at a vehicle and viewing at least a portion of a trailer hitched to the vehicle. With the trailer hitched to the vehicle and while the vehicle is operating in a calibration state and being driven straight, the system determines edges of the trailer. With the trailer hitched to the vehicle and after the vehicle is driven straight and while the vehicle is operating in the calibration state and being driven along a curved path, and at least in part via processing of captured frames of image data, the system determines a hitch point of the trailer hitched to the vehicle. With the vehicle not operating in the calibration state, and based in part on the determined hitch point of the trailer hitched to the vehicle, the system determines a jack-knife angle of the trailer relative to the vehicle.