Trailer Angle Estimation Using Projective Geometry and Visual Tracking

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Solution Overview

Problem

Tow vehicle drivers face challenges in maneuvering trailers due to confusion about steering angles, which can lead to jack-knifing and loss of course, and existing systems are costly and complex.

Innovation Solution

A system using a camera-mounted vehicle controller that determines trailer angles via projective geometry, tracking visual features from images to calculate the trailer angle and transmit it to vehicle systems, utilizing sensors for straight-line detection and projective transformations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a camera-based system with projective geometry is used to determine trailer angles, then device complexity and hardware requirements are reduced, but measurement precision may be affected compared to multi-sensor systems

Engineering Contradiction:
Improvehardware requirementsVSAvoidtrailer angle determination accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces complex mechanical sensor systems (multiple cameras, LIDAR, radar) with a simplified camera-based projective geometry system. A single camera captures images of the trailer, and computational projective geometry algorithms process these images to calculate trailer angle, eliminating the need for expensive multi-sensor hardware while maintaining functional capability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system creates a virtual 3D model of the trailer and its spatial relationship to the vehicle by projecting 2D camera images into 3D space using projective geometry. This virtual copy allows accurate angle determination without physical contact sensors or complex mechanical measurement devices attached to the trailer

Inventive Principle:
Principle #26Copying

2Ease of operation

If visual feature tracking is used to calculate trailer angles during movement, then ease of operation is improved, but reliability may be affected by image quality and feature detectability

Engineering Contradiction:
ImprovemaneuverabilityVSAvoidtrailer angle determination consistency
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system performs preliminary detection of visual features on the trailer before movement begins or during steady-state conditions. These pre-identified features serve as reference points that are tracked throughout subsequent maneuvers, ensuring consistent angle calculation even during dynamic movement when image quality may vary

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously tracks visual features across multiple frames and uses feedback from previous position estimates to refine current angle calculations. This temporal feedback mechanism maintains reliability during movement by comparing expected feature positions with actual detected positions and adjusting calculations accordingly

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4188774B1Vehicle trailer angle estimation via projective geometry
Publication Date: 2025.09.10 CONTINENTAL AUTONOMOUS MOBILITY US LLC
  • EP4188774B1 patent drawingFigure 1A
  • EP4188774B1 patent drawingFigure 1B
  • EP4188774B1 patent drawingFigure 2

AI summary

A method for determining a trailer angle between a tow vehicle and a trailer attached to the tow vehicle includes receiving images from a camera positioned on a rear portion of the tow vehicle with a data processing hardware device, determining visual features from the images, tracking the visual features while the tow vehicle and trailer are moving and calculating, at the data processing hardware, the trailer angle based on the visual features. The trailer angle is then transmitted from the data processing hardware to one or more vehicle systems.