Forward Collision Warning Using Contour Point Tracking
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Solution Overview
Problem
Conventional forward collision warning systems fail to accurately calculate a time to collision (TTC) when the bottom of a forward vehicle is not detected, particularly at low speeds, leading to potential collisions due to the inability to acquire a distance reference point.
Innovation Solution
The system extracts and tracks a contour candidate point, determines its relevance to the vehicle, estimates its height, and calculates the relative distance using the camera's focal length and the contour point's height, even when the traditional distance reference point is not available, allowing for timely collision warnings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the conventional forward collision warning system uses the bottom of the rear wheel or end of lower shadow area as a distance reference point, then the relative distance calculation is simple, but the system fails to detect the reference point when the forward vehicle is too close to the ego vehicle
Solution Approach 1:
The patent uses contour points as virtual copies of the distance reference point. Instead of relying on the physical bottom of the rear wheel or shadow end, the system extracts contour points from the vehicle's silhouette in the image and uses these as surrogate reference points for distance calculation, maintaining simplicity while improving detection reliability.
Solution Approach 2:
The patent changes the parameter used for distance reference from fixed physical features (wheel bottom, shadow end) to variable contour points on the vehicle silhouette. This parameter change allows the system to adapt to different vehicle positions and distances, particularly when vehicles are close together, while still enabling straightforward distance calculations.
2Stability of the object's composition
If the system tracks the bottom of the forward vehicle as a feature point, then the distance reference is stable, but the system cannot acquire a feature point when the forward vehicle is too close
Solution Approach 1:
The patent transitions from tracking a single point (bottom of vehicle) to tracking multiple contour points along the vehicle silhouette. By moving from one-dimensional point tracking to multi-point contour tracking, the system gains redundancy and can identify valid reference points even when the vehicle bottom is not visible due to proximity.
Solution Approach 2:
The contour point extraction method serves multiple functions: it identifies the vehicle silhouette, provides multiple candidate reference points, and enables distance calculation without requiring specific features like wheels or shadows. This multi-functionality ensures the system can operate reliably across various vehicle distances and configurations.
3Device complexity
If the system uses traditional distance reference points, then the calculation method is straightforward, but collision warnings are not generated in time when the forward vehicle is too close
Solution Approach 1:
The system performs preliminary contour point extraction and tracking before distance calculation is needed. By continuously identifying and tracking contour points in advance, the system ensures that valid reference points are already available when distance calculation and collision warning decisions must be made, reducing time delays while maintaining calculation simplicity.
Data Source
AI summary
A forward collision warning method may include the steps of: (a) extracting a contour candidate point of an object considered as the forward vehicle from an image taken by a camera; (b) tracking a movement of the contour candidate point over time; (c) determining whether the contour candidate point belongs to the vehicle; (d) setting the contour candidate point to a vehicle contour point of the forward vehicle, when it is determined at the step (c) that the contour candidate point belongs to the vehicle; (e) estimating a height of the vehicle contour point from the ground surface; (f) calculating a relative distance to the forward vehicle through Equation below; and (g) calculating a time to collision (TTC) using the relative distance:Z=λh-Ycyc.Equation