Pedestrian Protection Triggering via Signal Frequency Analysis
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Solution Overview
Problem
Current pedestrian protection systems face challenges in accurately differentiating between pedestrian impacts and other objects, leading to potential false deployments and reduced safety due to the similarity in sensor data from various collision types.
Innovation Solution
The method involves determining the frequency of the signal derived from accident signals using acceleration sensors, which distinguishes between pedestrian impacts and other objects based on their stiffness, allowing for more accurate differentiation and reduced risk of false deployments by analyzing the frequency characteristics of the vibration signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensor data analysis is used to detect pedestrian impacts, then the system can identify collision events, but it cannot accurately differentiate between pedestrian impacts and other objects leading to false deployments
Solution Approach 1:
The patent applies parameter changes by analyzing the frequency characteristic of acceleration signals rather than relying solely on traditional sensor data parameters. Different objects produce different vibration frequencies upon impact due to their varying stiffness properties. By extracting and analyzing the frequency parameter from the acceleration signal, the system can differentiate between pedestrian impacts (specific frequency range) and other objects (different frequency ranges), thereby improving measurement precision and reducing false deployments
Solution Approach 2:
The patent replaces traditional mechanical classification methods with signal processing and frequency analysis. Instead of relying on mechanical thresholds and simple sensor data comparison, the system uses spectral analysis of acceleration signals to identify the frequency signature of different impact objects. This substitution of mechanical decision-making with frequency-based signal processing enables more accurate differentiation between pedestrian impacts and other collision events
2Reliability
If the system increases sensitivity to detect all possible pedestrian impacts, then more pedestrian collisions are detected, but the risk of unintentional faulty deployment increases due to inability to distinguish from other objects
Solution Approach 1:
The patent changes the detection parameter from simple acceleration thresholding to frequency-based analysis. By monitoring the frequency characteristic of the acceleration signal, the system can maintain high sensitivity for detecting pedestrian impacts while simultaneously filtering out false signals from other objects. Each object type produces a characteristic frequency signature, allowing the system to distinguish between genuine pedestrian impacts and other collision events even when both produce similar acceleration magnitudes
Solution Approach 2:
The system implements feedback by continuously analyzing the frequency characteristic of incoming acceleration signals and using this information to modulate the deployment decision. The frequency analysis provides real-time feedback about the nature of the impact, allowing the control unit to confirm or reject deployment commands based on whether the detected frequency matches the expected range for pedestrian impacts
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables better protection of pedestrians by accurately identifying pedestrian impacts and reducing the risk of unintentional faulty deployments, thereby enhancing safety and improving the differentiation between deployment and non-deployment cases.
Implementation Method 1
determining a frequency of a signal derived from the accident signal... different objects have a different stiffness and therefore result in a different excitation frequency
Implementation Method 2
The frequency is preferably detected by an acceleration sensor or by multiple acceleration sensors or by knock sensors
Data Source
AI summary
A device and a method for triggering passenger protection devices, an accident sensor system generating a first signal and the passenger protection devices being triggered as a function of a frequency of a second signal, which is derived from the first signal, the frequency being determined as a function of a first length of a first signal characteristic of the second signal and of a second length of a second signal characteristic of the added-up second signal.