Trailer Hitch Angle Estimation Under Blurred Camera Images
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Solution Overview
Problem
Existing technologies fail to accurately estimate the hitch angle of a trailer in the world coordinate system when the image captured by a camera mounted on a towing vehicle is blurred.
Innovation Solution
A hitch angle estimation device and method that perform a transformation from a view coordinate system to a world coordinate system, followed by straight line fitting and Kalman filter processing, using a kinematic model to estimate the hitch angle based on clear and blurred images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image-based trailer angle measurement is used, then the hitch angle can be estimated visually, but the estimation becomes inaccurate when the camera image is blurred
Solution Approach 1:
The patent introduces a coordinate transformation intermediary that converts image coordinates to world coordinates, enabling the system to work with geometric relationships rather than directly processing blurred image data. This transformation layer acts as a mediator between the ambiguous image data and the precise angle estimation requirement
Solution Approach 2:
The patent implements feedback through the Kalman filter process, which continuously refines the hitch angle estimation by comparing predicted values from the kinematic model with actual measurements. This feedback mechanism allows the system to correct errors and maintain accuracy even when individual measurements are degraded by image blurring
2Stability of the object's composition
If Kalman filter process is applied for each trailer angle measurement, then the angle estimation can be smoothed, but the process cannot handle blurred images appropriately
Solution Approach 1:
The patent performs coordinate transformation from view coordinates to world coordinates as a preliminary action before applying the Kalman filter. This preprocessing step ensures that the data is in the correct reference frame, allowing the subsequent filtering to effectively improve stability without sacrificing precision
Solution Approach 2:
The patent changes the coordinate system parameter from view coordinates to world coordinates, fundamentally altering how the data is represented and processed. This parameter transformation enables the system to achieve both stability through filtering and precision in the final hitch angle estimation
Data Source
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Figure 3A~3C
AI summary
A hitch angle estimation device performs a transformation from a view coordinate system to a world coordinate system on a point sequence indicating a tow bar on an image shot by a camera mounted on a vehicle towing a trailer via the tow bar and a point sequence indicating a lower end portion of the trailer on the image, performs a straight line fitting of the point sequence indicating the tow bar after the transformation and the point sequence indicating the lower end portion after the transformation, calculates a hitch angle of the trailer in the world coordinate system based on a straight line indicating the tow bar in the world coordinate system and a straight line indicating the lower end portion in the world coordinate system obtained by the straight line fitting, and performs a Kalman filter process on the hitch angle in the world coordinate system.