Contact Time Calculation Using Arbitrary Point Differences
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Solution Overview
Problem
Existing contact time calculation methods for obstacles detected by on-vehicle cameras are prone to errors due to vehicular movements like pitching and yawing, which affect the accuracy of calculating the time before an obstacle contacts the vehicle.
Innovation Solution
A contact time calculation apparatus that extracts two arbitrary points on an image from an on-vehicle camera, calculates their coordinate differences, and determines the time differential value based on multiple images to accurately predict the time of contact, independent of the vanishing point's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the contact time is calculated using a coordinate system with the origin at the vanishing point and optical flow of characteristic points, then the contact time can be determined, but an error occurs due to vehicular behavior such as pitching and yawing causing the vanishing point to move
Solution Approach 1:
The invention extracts two arbitrary points from the object in the image and calculates contact time based on their coordinate differences, eliminating the need to track the vanishing point. This extraction of essential measurement points from the problematic reference frame resolves the contradiction by maintaining measurement capability while avoiding the reliability issue of vanishing point movement
Solution Approach 2:
Instead of tracking the vanishing point's movement to calculate contact time (traditional approach), the invention inverts the approach by using fixed arbitrary points and calculating their coordinate differences. This inversion eliminates the dependency on vanishing point stability while maintaining contact time calculation accuracy
2Ease of operation
If the vanishing point is used as the origin for contact time calculation, then the calculation can be performed, but the vanishing point moves due to pitching and yawing causing errors
Solution Approach 1:
The invention extracts two arbitrary points from the object and uses their coordinate differences for contact time calculation, removing the vanishing point from the calculation process. This maintains operational simplicity while improving accuracy by eliminating the source of error
Solution Approach 2:
The invention changes the reference parameters from vanishing point coordinates to arbitrary point coordinate differences. This parameter change allows the system to remain simple in operation while achieving higher measurement precision by using stable, arbitrary reference points instead of the moving vanishing point
Data Source
AI summary
Two arbitrary points belonging to a single object in an image captured by an camera installed in a vehicle body are extracted as evaluation points, the absolute value representing the difference between the coordinate values of the extracted two points, which are taken in reference to an arbitrary coordinate axis set on the image, is calculated and a time differential value of the absolute value representing the difference between the coordinate values of the two points is determined. Based upon the absolute value representing the difference between the coordinate values and the time differential value, the length of time to elapse before the object containing the two extracted points contacts the vehicle body is calculated.