Trailer Assist Camera Calibration for Jack-Knife Angle Detection
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Solution Overview
Problem
Existing vehicle trailer assist systems face challenges in accurately calibrating and detecting the trailer hitch and collision angles during the initial hitching of a new trailer, which can lead to difficulties in smooth operation and safety concerns.
Innovation Solution
A vehicle vision system equipped with a rearward-facing camera and an electronic control unit (ECU) that processes image data to determine an initial trailer template, detect image edges, and calculate the hitch ball location through a calibration maneuver, including a series of frames captured at different trailer angles, allowing for precise trailer angle detection and collision angle estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a trailer is hitched to the vehicle via a pivoting joint, then the trailer can be connected to the vehicle, but the trailer angle relative to the vehicle changes during turning maneuvers making calibration difficult
Solution Approach 1:
The system performs a calibration maneuver before normal operation to establish reference data. The vehicle executes a specific driving pattern (straight line followed by a turn) to capture image frames at known trailer angles, storing these frames for subsequent template matching and hitch ball location calculation.
Solution Approach 2:
The system creates a template copy of the trailer appearance from calibration images. This template is then matched against new images to detect trailer edges and determine trailer angles without requiring direct angle measurement, thereby resolving the measurement difficulty caused by the pivoting joint.
2Measurement precision
If image data is captured during a turning portion of calibration maneuver at different trailer angles, then comprehensive calibration data is obtained, but the complexity of processing multiple frames increases
Solution Approach 1:
The system extracts only the essential information from multiple calibration frames - specifically, it creates a single composite template representing the trailer and calculates the hitch ball location. This extracted template is then used for all subsequent angle detections, significantly reducing processing complexity while maintaining calibration accuracy.
Solution Approach 2:
All complex image processing operations are performed during the preliminary calibration phase. The system processes multiple frames to create the template and determine the hitch ball location once, before normal operation. During actual trailering, only simple template matching is required, reducing ongoing processing complexity.
3Measurement precision
If the system determines the hitch ball location through image processing, then accurate trailer angle detection is achieved, but the calibration process requires specific driving maneuvers
Solution Approach 1:
The system performs self-calibration by automatically executing the calibration maneuver and processing images without user intervention. The driver simply needs to perform the specified driving pattern, and the system automatically captures images, processes them to find the hitch ball location, and stores the calibration data.
Solution Approach 2:
The system replaces manual measurement methods with automated image processing. Instead of requiring physical measurement tools or manual angle gauges, the system uses computer vision to detect the hitch ball location and calculate trailer angles, making the process more accurate and easier to perform.
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. The system, during a first turning maneuver of a calibration maneuver of the vehicle and trailer, stores a subset of the frames of image data captured by the camera. Each stored frame of the stored subset of the frames captures the trailer at a respective different trailer angle relative to a longitudinal axis of the vehicle. The system determines image data edges for each stored frame of image data. The system, after performing the first turning maneuver of the calibration maneuver and during a second turning maneuver of the calibration maneuver, and based at least in part on the determined image data edges for the stored frames of image data, determines a jack-knife angle of the trailer relative to the longitudinal axis of the vehicle.