Capacitive Occupant Detection Using Embedded Wire Mesh in Vehicle Seats
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Solution Overview
Problem
Current vehicle interior detection systems for occupant presence or absence, particularly in seats and steering wheels, face challenges in achieving high reliability and easy installation while maintaining sensitivity, especially in varying occupant positions and conditions.
Innovation Solution
A capacitive detection device with electrically conductive wires attached to vehicle components, using a signal generating unit to apply a time-varying signal and an electrically conductive layer to amplify capacitance changes, allowing for enhanced sensitivity and easy installation, integrated with a signal evaluation unit for reliable occupant detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional capacitive sensors are installed on the B-surface of vehicle seats, then integration is simplified and robustness is improved, but detection sensitivity and reliability are compromised
Solution Approach 1:
The patent transitions from traditional planar capacitive sensors on the B-surface to a three-dimensional wire mesh structure embedded within the foam body. This spatial transformation from 2D surface mounting to 3D volumetric integration enables the detection system to sense occupant presence through multiple depth layers, significantly improving both sensitivity and reliability while maintaining ease of integration during seat manufacturing.
Solution Approach 2:
The invention integrates electrically conductive wires directly into the foam body matrix, creating a composite structure where the foam serves as both structural support and sensor substrate. This composite approach eliminates the need for separate sensor mounting layers, ensuring mechanical robustness while maintaining detection sensitivity through the distributed wire network embedded throughout the foam volume.
2Measurement precision
If complex detection systems are implemented to improve occupant detection accuracy, then measurement precision is improved, but device complexity and installation difficulty increase
Solution Approach 1:
The wire mesh structure serves multiple functions simultaneously: it provides structural reinforcement to the foam body, enables capacitive sensing throughout the seat volume, and acts as an integrated electrode system. This multi-functionality eliminates the need for separate sensor arrays, wiring harnesses, and mounting structures, significantly reducing overall system complexity while maintaining high detection accuracy.
Solution Approach 2:
The patent merges the structural foam body with the sensing element by embedding the conductive wire mesh directly within the foam during manufacturing. This consolidation of structure and sensor into a single integrated component eliminates complex assembly steps and reduces the number of separate parts, thereby simplifying both device structure and installation process while preserving detection precision.
3Measurement precision
If multiple sensors are deployed to improve detection coverage, then measurement precision is improved, but device complexity and installation effort increase
Solution Approach 1:
The wire mesh is divided into multiple segments or zones during the manufacturing process, with each segment independently embedded into corresponding regions of the foam body. This segmentation allows for modular assembly and simplifies installation, as the wire segments can be individually positioned and connected without requiring complex full-coverage wiring, thereby maintaining comprehensive detection coverage while reducing installation complexity.
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 provides improved sensitivity and reliability in detecting occupant presence or absence, enabling effective input for safety systems like seat belt reminders and automatic driver assistance, while reducing hardware effort through the use of existing components like seat heater wires.
Implementation Method 1
a capacitive detection device with electrically conductive wires attached to vehicle components, using a signal generating unit to apply a time-varying signal
Implementation Method 2
an electrically conductive layer to amplify capacitance changes, allowing for enhanced sensitivity and easy installation
Data Source
AI summary
A capacitive detection device and capacitive detection system for use in a vehicle interior includes at least one electrically conductive wire, at least partially attached to a component of the vehicle interior, and at least one electrically conductive layer that is arranged in close proximity to the at least one electrically conductive wire, compared to a potential minimum distance to a vehicle occupant, wherein a galvanic connection between the at least one electrically conductive layer and the at least one electrically conductive wire is avoided.