Trailer Angle Detection Using Vanishing Point Vision
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Solution Overview
Problem
Existing methods for determining the angular position of a trailer relative to a towing vehicle are restrictive and require calibration, limiting their applicability, especially for trailers like those transporting tanks or wood, as they assume a plane perpendicular to the camera's optical axis and need a straight-line drive for reference positioning.
Innovation Solution
A system using a camera on the towing vehicle to detect lines parallel to the trailer axis, calculating the vanishing point, and determining the pitch, yaw, and roll angles without the need for calibration or straight-line driving, by implementing a line-detection algorithm and using reference frames to derive the angles from image coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a calibration phase with straight-line driving is implemented to determine reference position, then measurement precision of yaw angle is improved, but ease of operation deteriorates and productivity decreases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the relationship between vanishing point positions and yaw angles in a lookup table during system initialization. This allows the system to determine yaw angles directly from vanishing point coordinates without requiring real-time calibration or straight-line driving, thus improving ease of operation while maintaining measurement precision through the pre-established reference data.
2Device complexity
If assumption of plane perpendicular to optical axis is made, then device complexity is reduced, but adaptability deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters used for angle determination. Instead of assuming the trailer front face is perpendicular to the optical axis, the system uses vanishing point detection in perspective projection, which accounts for arbitrary trailer orientations and geometries. This changes the fundamental parameter from fixed geometric assumption to dynamic perspective-based calculation, enabling adaptability across different trailer types while maintaining reasonable system complexity.
3Measurement precision
If calibration phase is required, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent eliminates calibration time by performing all necessary reference calculations during system initialization. The lookup table containing vanishing point to yaw angle mappings is pre-computed and stored, allowing immediate angle determination upon image capture without requiring the towing vehicle to perform calibration maneuvers, thus completely removing the time loss associated with calibration while preserving measurement precision.
4Adaptability or versatility
If vanishing point detection method is used, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary element: a lookup table that mediates between vanishing point detection and yaw angle calculation. The complex relationship between perspective projection parameters and angular positions is pre-computed and stored in this intermediary structure. This allows the system to benefit from the adaptability of vanishing point detection while reducing runtime complexity by replacing complex real-time calculations with simple table lookups based on detected vanishing point coordinates.
Data Source
AI summary
A system for determining at least one pitch angle of a trailer relative to a towing vehicle, the system including a camera mounted on the towing vehicle and capable of acquiring images of the trailer in which lines of the trailer parallel to the axis of the trailer are visible, and a computer configured to perform the following steps: implementing a line-detection algorithm on at least one image of the trailer acquired by the camera, detecting in the image the lines of the trailer parallel to the trailer axis, corresponding to vanishing lines, and deducing from the vanishing lines a position of the vanishing point, and from the coordinates of the vanishing point, determining at least one pitch angle of the trailer with respect to the towing vehicle.