Sensor Cord for Pedestrian Protection
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Solution Overview
Problem
Existing pedestrian protection device detection systems require complex and costly fluid-filled tubes for pressure detection, and lack the ability to measure the magnitude of pressing forces effectively.
Innovation Solution
A sensor cord comprising a deformable insulation layer with three linear members, each with a conductive layer of at least 250 Ω/m resistance, where the third linear member deforms under pressure, allowing for the detection of pressing force magnitude without a fluid-filled tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluid-filled tube is used for pressure detection, then the detection device can detect pressure changes, but the end portions of the tube need to be kept airtight which makes processing complicated and expensive
Solution Approach 1:
The patent extracts the fluid-filled tube from the system and replaces it with a solid-state sensor cord containing conductive layers. This eliminates the need for airtight sealing at end portions while maintaining pressure detection capability through resistance changes in the conductive layers when deformed by external pressure.
Solution Approach 2:
The patent replaces the mechanical fluid-filled tube system with an electrical resistance-based detection system. The sensor cord uses changes in electrical resistance of conductive layers under mechanical deformation to detect pressure, substituting the mechanical fluid pressure transmission system with an electrical measurement system.
2Reliability
If a fluid-filled tube is used for pressure detection, then pressure changes can be detected, but long-term reliability cannot be promised
Solution Approach 1:
The patent employs solid-state conductive layers that are more durable and reliable than fluid-filled tubes over the long term. The sensor cord components can withstand repeated deformation cycles without degradation, ensuring long-term reliability for pedestrian protection systems.
3Measurement precision
If a single resistance wire and conductive wire are used as in Patent Document 3, then position detection is achieved, but the magnitude of pressing force cannot be detected
Solution Approach 1:
The patent uses multiple conductive layers with different resistance values arranged in specific patterns within the sensor cord. By measuring resistance changes in each layer independently, the system can determine both the position of applied pressure and its magnitude, as different layers respond differently to the same pressure based on their local resistance properties.
Solution Approach 2:
The sensor cord employs a composite structure with multiple conductive layers having different resistance characteristics. This composite arrangement allows the system to extract multiple parameters (position and magnitude) from the same physical stimulus by analyzing the combined response of layers with different electrical properties.
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 sensor cord reduces manufacturing costs, enhances long-term reliability, and accurately detects the position and magnitude of pressing forces, improving detection accuracy and system sensitivity.
Implementation Method 1
The third linear member is configured to deform at a portion where pressure is applied. Resistance of the portion where the pressure is applied is configured to vary depending on an amount of deformation.
Data Source
AI summary
The sensor cord of the present disclosure includes a first linear member, a second linear member, a third linear member, and a deformable insulation layer containing the first to third linear members. On a cross-sectional surface of the sensor cord taken perpendicular to longitudinal directions of the sensor cord, the third linear member is situated between the first linear member and the second linear member and contacts the first linear member and the second linear member. In each of the first linear member, the second linear member, and the third linear member, at least an outermost peripheral part has electrical conductivity and has resistance greater than or equal to 250 Ω/m in the longitudinal directions. The third linear member is configured to deform at a portion where pressure is applied. Resistance at the portion where the pressure is applied varies depending on an amount of deformation.