Tapered Foil Switching Element for Pedestrian Collision Detection
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Solution Overview
Problem
Current pressure sensors, such as Force Sensitive Resistor (FSR) based sensors, have a limited measuring range and insufficient dynamic response to detect the high-magnitude pressure pulses caused by pedestrian collisions, making them inadequate for reliable pedestrian protection systems.
Innovation Solution
A foil-type switching element with a spacer having multiple regions of different sizes in the active area, where electrodes actuate and shunt resistors as pressure increases, broadening the measurement range and providing a reliable detection of pressure evolution, and incorporating an elongate resistive layer and shunt electrodes aligned with a tapering spacer opening to enhance pressure-dependent electrical response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If FSR-based pressure sensors are used, then robustness and ease of manufacture are improved, but measuring range and dynamic response are insufficient for detecting high-magnitude pressure pulses
Solution Approach 1:
The active area is divided into multiple regions with different sizes, each having a different activation pressure threshold. This segmentation allows the sensor to detect a broader range of pressure magnitudes by sequentially activating different regions as pressure increases, resolving the contradiction between ease of manufacture and measuring range.
Solution Approach 2:
Different regions of the active area are given different properties (different sizes and activation thresholds) to optimize their function for specific pressure ranges. This local differentiation enables the sensor to maintain manufacturing simplicity while achieving extended measurement capability across multiple pressure magnitudes.
2Reliability
If FSR-based pressure sensors are used, then robustness is improved, but dynamic response is insufficient to detect pressure evolution
Solution Approach 1:
The sensor incorporates multiple regions that dynamically activate in sequence as pressure increases, enabling the sensor to track pressure evolution over time. This dynamic response capability maintains robustness while improving the speed of detection for pressure changes during collision events.
3Measurement precision
If multiple regions with different activation thresholds are added, then measurement range is broadened, but device complexity increases
Solution Approach 1:
Multiple functional regions are merged into a single integrated sensor structure with a unified spacer and electrode configuration. This merging approach broadens the measurement range through regional differentiation while minimizing the increase in device complexity by maintaining a cohesive design.
4Measurement precision
If the active area is divided into multiple regions, then sensitivity to different pressure levels is improved, but manufacturing precision requirements increase
Solution Approach 1:
Different regions are designed with locally optimized properties (different sizes and thresholds) to enhance sensitivity across pressure levels. The manufacturing precision requirements are managed by implementing these local variations within the existing FSR manufacturing framework, balancing sensitivity improvement with manufacturability.
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
The solution enables a broader measurement range and reliable detection of pressure, including low pressures, with improved sensitivity and integrity verification, addressing the limitations of existing FSR-based sensors in pedestrian collision detection systems.
Implementation Method 1
In response to an activation pressure applied on the switching element, the electrode means are mechanically actuated
Implementation Method 2
the electrode means are mechanically actuated and cause shunting of at least part of the associated resistor means
Implementation Method 3
a first carrier foil and a second carrier foil arranged at a certain distance from each other by means of a spacer
Data Source
AI summary
A foil-type switching element comprises a first carrier foil and a second carrier foil arranged at a certain distance from each other by means of a spacer, which comprises one opening (18) defining an active area. An elongate resistive layer (20) is provided on the second carrier foil within the active area while elongate 5 shunt means (22) are arranged on the first miler foil within the active area and facing the resistive layer (20). The form of the opening (18) in the spacer is such that the active area generally tapers in the longitudinal direction of the elongate resistive layer (20), so that when pressure is applied on the switching element, the shunt means (22) shunt a portion of the resistive layer (20) that 10 progressively increases with pressure, from the broad end of the spacer opening (18) towards its narrow end.