Trailer Hitch Angle Detection via Image Warping
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Solution Overview
Problem
Existing vehicle vision systems face difficulties in detecting objects that move in a circular motion around a pivot, such as a trailer hitched to a vehicle, due to pose, angle, and rotation changes, which alter feature points and increase detection complexity.
Innovation Solution
The system warps images around a pivot position to transform pivotal movement into lateral movement, allowing objects to be detected more easily by converting their orientation from pivoting to vertical, thereby simplifying the detection process and reducing pose and scale variance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If the system detects objects that move in circular motion around a pivot (trailer hitch), then the detection capability is required, but the pose, angle, and rotation changes alter feature points and increase detection complexity
Solution Approach 1:
The system transforms the circular motion detection problem in 2D image space into a 1D angular measurement problem by defining an angular coordinate system centered at the pivot point. Objects are detected and tracked using angular position relative to the pivot, converting complex 2D pose estimation into simpler angular measurement, thereby reducing detection complexity while maintaining reliability.
Solution Approach 2:
The system introduces a pivot point as an intermediary reference frame centered at the trailer hitch location. All object positions are measured relative to this pivot point in angular coordinates rather than absolute image coordinates. This intermediary reference frame stabilizes feature point representation by anchoring all measurements to a fixed pivot, eliminating the reliability issues caused by arbitrary pose changes.
2Productivity
If the system processes images with objects at varying orientations, then comprehensive object detection is achieved, but computational complexity and processing time increase
Solution Approach 1:
The system changes the coordinate representation from 2D Cartesian coordinates to 1D angular coordinates measured from the pivot point. This dimensionality reduction simplifies the image processing by converting complex 2D orientation and position estimation into simpler angular measurement, thereby improving detection efficiency while reducing processing complexity.
Solution Approach 2:
The system changes the parameter space for object representation from absolute position and orientation parameters to relative angular parameters centered at the pivot. By parameterizing all object states in terms of angular displacement from the pivot, the system simplifies the mathematical models required for detection and tracking, reducing both computational complexity and processing time.
3Measurement precision
If the system uses a rear camera with field of view encompassing the trailer, then the trailer can be detected, but the pivotal movement of the trailer creates pose variance that complicates detection
Solution Approach 1:
The system uses the pivot point at the trailer hitch as an intermediary reference that remains fixed in the image frame while the trailer moves. By measuring trailer position and orientation relative to this fixed pivot point using angular coordinates, the system achieves precise angle detection without being affected by the trailer's pivotal movement, thereby improving measurement precision while reducing detection difficulty.
Data Source
AI summary
A trailering assist system includes a control and a camera disposed at a rear portion of a vehicle and having a field of view at least rearward of the vehicle. The control includes an image processor operable to process image data captured by the camera. The control, responsive to image processing of captured image data, transforms captured image data of the trailer hitch from a pivoting orientation of the portion of the trailer that pivots about the trailer hitch to a vertical orientation of the portion of the trailer that moves laterally across the transformed image data. The control transforms pivotal movement of the portion of the trailer about the trailer hitch to lateral movement of the trailer hitch in the transformed image data. The control determines a trailer angle of the trailer relative to the vehicle based on the lateral position of the trailer hitch in the transformed image data.