AEB TTC Thresholding Using Target Acceleration for Hard Braking
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Solution Overview
Problem
Traditional automatic emergency braking (AEB) systems face challenges in determining accurate time-to-collision (TTC) thresholds due to non-linear ideal braking profiles and deviations in actual braking performances, leading to suboptimal braking results, especially when encountering aggressively stopping vehicles.
Innovation Solution
The implementation of AEB systems that calculate TTC thresholds based on target acceleration, using sensor data to determine vehicle and target velocities, accelerations, and distances, allowing for more accurate TTC determination and earlier activation of braking forces to avoid collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional non-linear ideal braking profiles are used for AEB, then the system can provide maximum deceleration in ideal conditions, but determining accurate TTC thresholds becomes difficult and actual braking performance deviates from ideal profiles
Solution Approach 1:
The patent transforms the complex non-linear braking problem into a linear parameter space by using TTC as the independent variable. The braking force is expressed as a linear function of TTC: F_braking(t) = m*(v0/t - a), where t represents TTC. This linearization allows accurate TTC threshold determination while maintaining optimal braking performance throughout the deceleration process.
Solution Approach 2:
The system pre-calculates TTC thresholds based on target acceleration before actual braking situations occur. By determining appropriate TTC thresholds in advance for different target acceleration scenarios, the system avoids the complexity of real-time non-linear calculations and ensures accurate collision prediction when emergencies occur.
2Device complexity
If AEB systems use fixed TTC thresholds, then the system is simple to implement, but it fails to account for aggressive stopping scenarios and produces suboptimal braking results
Solution Approach 1:
The patent makes the TTC threshold dynamic by linking it to target acceleration. Instead of using a fixed threshold, the system adjusts the TTC threshold based on the measured acceleration of the target vehicle. When target acceleration indicates aggressive stopping, the system automatically lowers the TTC threshold, enabling earlier and more appropriate braking activation for high-risk scenarios.
Solution Approach 2:
The system continuously monitors target acceleration and uses this feedback to adjust TTC thresholds in real-time. By measuring the target's acceleration pattern and comparing it against predefined thresholds, the system adapts its collision prediction parameters dynamically, improving reliability without requiring overly complex fixed-rule systems.
3Reliability
If AEB systems activate braking early to ensure collision avoidance, then safety is improved, but unnecessary braking may occur in non-critical situations
Solution Approach 1:
The patent uses target acceleration as a key parameter to modulate TTC thresholds. By incorporating acceleration data into the threshold calculation, the system distinguishes between critical scenarios (aggressive stopping with high negative acceleration) and non-critical scenarios (normal driving variations). This parameter-based adjustment ensures braking is activated early only when truly necessary, maintaining both safety and operational appropriateness.
Data Source
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AI summary
Techniques and systems are described that enable automatic emergency braking (AEB) using a time-to-collision (TTC) threshold that is based on target acceleration. The TTC may be a combination of a first TTC sub-threshold and a second TTC sub-threshold. The first TTC threshold may be based on a vehicle velocity of a host vehicle and a relative velocity between the host vehicle and a target object. The second TTC sub-threshold may be based on a target acceleration of the target object and a distance between the host vehicle and the target object. By utilizing the target acceleration in the TTC threshold determination, the techniques and systems described herein enable AEB to work as planned to prevent a collision between a vehicle and a target, in a wider variety of environments and situations.