Vehicle Collision Control Using Speed-Dependent Braking Thresholds
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Solution Overview
Problem
Conventional collision damage mitigation systems activate automatic braking unnecessarily or provide insufficient deceleration when the driver attempts to avoid a collision through steering, particularly at higher vehicle speeds.
Innovation Solution
A vehicle control apparatus that calculates steering start time thresholds based on varying lateral accelerations according to vehicle speed, delaying automatic braking activation until either the steering or automatic braking start time thresholds are met, thereby avoiding unnecessary braking and ensuring sufficient deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If automatic braking is activated when the time to collision equals the steering limit time to collision TTCc, then the automatic braking can be activated in time to ensure sufficient deceleration, but unnecessary activation of automatic braking occurs when the driver is trying to avoid collision by steering
Solution Approach 1:
The patent changes the parameter used for automatic braking activation from a fixed time threshold to a speed-dependent time threshold. Specifically, it uses a smaller lateral acceleration value for higher vehicle speeds, resulting in a longer steering start time threshold and thus delaying automatic braking activation at high speeds while maintaining timely activation at lower speeds.
Solution Approach 2:
The patent makes the automatic braking activation threshold dynamic by adjusting it based on vehicle speed. The system adapts the lateral acceleration parameter according to speed conditions, making the braking activation timing flexible rather than fixed, thereby resolving the contradiction between timely braking and avoiding unnecessary activation.
2Device complexity
If a fixed lateral acceleration value is used for trajectory calculation, then the calculation is simple, but the automatic braking activation timing is inappropriate at higher vehicle speeds
Solution Approach 1:
The patent changes the lateral acceleration parameter from a fixed value to a speed-dependent value. When vehicle speed exceeds a predetermined threshold, a smaller lateral acceleration value is used for trajectory calculation, which appropriately delays the automatic braking activation timing for high-speed conditions while maintaining simple calculation logic.
Data Source
AI summary
A vehicle control apparatus is configured to: obtain, based on a predetermined lateral acceleration for a trajectory calculation, a steering start time threshold which is a time which it takes for a host vehicle to collide with an object at a time point at which a driver of the host vehicle has to start steering the host vehicle in order to avoid a collision between the host vehicle and the object; and start an automatic braking, when an obtained predicted time to collision becomes shorter than or equal to either one of the steering start time threshold and an automatic braking start time threshold, whichever is shorter. The automatic braking start time threshold is a time which it takes for the host vehicle to collide with the object at a time point at which the automatic braking has to be started in order to avoid the collision between the host vehicle and the object.