Adaptive Collision Judgment Threshold for Short Margin Time
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Solution Overview
Problem
Existing collision judgment apparatuses face difficulties in accurately determining the probability of collision between a vehicle and an object when the collision margin time (TTC) is short, as the horizontal-direction angle of the object with respect to the vehicle changes rapidly in such scenarios.
Innovation Solution
A collision judgment apparatus that includes a distance detecting unit, relative speed detecting unit, margin time calculation unit, angle detecting unit, variation calculation unit, judgment value setting unit, and judgment unit, which calculates the variation of the angle over time and sets a larger judgment value for shorter collision margin times, determining the likelihood of collision based on this variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the collision margin time TTC becomes shorter, then the response time for collision avoidance is reduced, but the horizontal-direction angle of the object with respect to the vehicle changes rapidly making accurate collision judgment difficult
Solution Approach 1:
The patent applies dynamics by making the judgment threshold adaptive rather than fixed. The threshold dynamically adjusts based on the collision margin time TTC - when TTC is short, the threshold is set higher to account for rapid angle changes, and when TTC is long, the threshold is set lower. This dynamic adaptation resolves the contradiction by allowing accurate collision judgment across varying time conditions despite angle instability.
Solution Approach 2:
The patent changes the parameter of the judgment threshold based on the collision margin time. By setting different threshold values according to different TTC conditions, the system maintains accurate collision probability judgment even when angle measurements are unstable due to short response times. This parameter change strategy directly addresses the measurement precision issue under time constraints.
2Reliability
If the judgment threshold is set high to account for rapid angle changes, then collision probability is underestimated, but if set low, false collisions are detected
Solution Approach 1:
The patent implements feedback by using the collision margin time TTC as a basis for automatically adjusting the judgment threshold. The system continuously monitors TTC and adjusts the threshold accordingly, creating a closed-loop control mechanism. This feedback approach resolves the contradiction by automatically adapting the threshold to current conditions, eliminating the need for complex manual judgment threshold settings while maintaining high reliability.
3Ease of operation
If the angle variation threshold is fixed, then the system is simple to operate, but it cannot accurately judge collision probability when collision margin time varies
Solution Approach 1:
The patent transforms the static judgment threshold into a dynamic one that automatically adapts to varying collision margin times. This dynamic approach maintains ease of operation because the system performs the adjustment automatically based on measured TTC, while simultaneously improving reliability by accounting for different time conditions. The system remains simple to operate but becomes accurate across varying conditions through this dynamic adaptation.
Data Source
AI summary
A collision judgment apparatus includes: a distance detecting unit detecting distance between a vehicle and an object; a relative speed detecting unit detecting a relative speed therebetween; a margin time calculation unit calculating a time to collision therebetween, based on the distance and the relative speed; an angle detecting unit detecting an angle of the object with respect to a running direction of the vehicle; a variation calculation unit calculating a variation of the angle over time; a setting unit setting a judgment value such that the shorter the margin time, the larger the judgment value; and a judgment unit judging that the vehicle is likely to collide with the object when the variation of the angle calculated by the variation calculation unit is lower than the judgment value set by the setting unit.