Vehicle Frame Shear Wave Crash Characterization
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Solution Overview
Problem
Current methods for detecting vehicle crash events using acoustic emission sensors struggle to accurately determine the severity and direction of impacts, often deploying supplemental restraints unnecessarily or failing to deploy them in time due to limitations in wave propagation and signal processing.
Innovation Solution
The method employs at least three, preferably four, longitudinally and laterally distributed acoustic emission sensors to extract shear wave energy, which is non-dispersive and travels at a known velocity, allowing for the determination of impact severity and direction by analyzing signal amplitudes and time-of-arrival differences, and uses a digital signal processor to classify crashes and deploy restraints appropriately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic emission sensors are used to detect crash events, then crash detection capability is provided, but accuracy in determining impact severity and direction is insufficient
Solution Approach 1:
The patent segments the acoustic emission detection by separating shear wave signal processing from other wave components. Specifically, the system extracts shear wave signals from the total acoustic emission signals and processes them separately to determine impact characteristics, thereby improving measurement precision while maintaining reliability
Solution Approach 2:
The patent adds the dimension of shear wave-specific processing to the traditional acoustic emission detection. By introducing shear wave extraction and utilizing the non-dispersive nature of shear waves with known velocity, the system can accurately determine both impact severity and direction, resolving the contradiction between detection capability and characterization accuracy
2Measurement precision
If multiple sensors are distributed on the vehicle frame, then impact direction determination is enabled, but system complexity increases
Solution Approach 1:
The patent makes the distributed sensor system multi-functional by enabling it to perform both impact detection and impact direction determination using the same sensor array. The shear wave signal processing methodology allows the system to extract multiple pieces of information (impact severity, impact direction) from the same set of sensors, thereby improving measurement precision without proportionally increasing device complexity
Solution Approach 2:
The patent replaces complex mechanical impact analysis with acoustic emission-based shear wave processing. By substituting direct mechanical measurement with acoustic wave propagation analysis, the system can determine impact direction through signal processing rather than complex mechanical sensing, reducing overall system complexity while maintaining high measurement precision
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 provides timely and accurate deployment of restraints by characterizing crash events with enhanced precision, distinguishing between crash and non-crash events, and enabling 3D impact vector determination for improved safety.
Implementation Method 1
Acoustic Emission (AE) sensors have been used for failure analysis in metal structures because deformations due to structural impacts or shifting produce acoustical waves that travel through the structure
Implementation Method 2
Since shear waves are non-dispersive and travel through the vehicle frame at a known velocity, they can be detected in any part of the frame
Data Source
AI summary
A vehicle crash event is detected and characterized based on the transmission of acoustical shear waves through the vehicle frame. At least three, and preferably four or more, acoustical emission sensors longitudinally and laterally distributed on the vehicle frame produce acoustical signals that are processed to extract the shear wave energy due to impacts. Since shear waves are non-dispersive and travel through the vehicle frame at a known velocity, they can be detected in any part of the frame. The extracted shear wave signals are used not only to judge the severity of the impact, but also to characterize the type of crash and determine the direction of the impact based on when the shear wave is detected by each of the acoustical emission sensors.