Notched Foam Cushion for Accurate Occupant Weight Detection
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Solution Overview
Problem
Existing occupant sensing systems struggle to reliably distinguish between a light-weight normally seated adult and a cinched-down child seat, as the apparent weight of the child seat is increased by cinching, making it difficult to accurately represent the weight distribution and differentiate between the two types of occupants.
Innovation Solution
A notched foam bottom seat cushion with a pressure-responsive sensor disposed between the cushion and the seat frame, where the notch limits and directs occupant loading, allowing the sensor to differentiate between a normally seated occupant and a cinched-down child seat by focusing the load within the sensor's detection area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure-responsive sensor is used under the foam cushion to detect occupant weight, then the system can detect the presence of an occupant, but it cannot reliably distinguish between a cinched-down child seat and a light-weight normally seated adult because the apparent weight of the child seat is increased by cinching
Solution Approach 1:
The foam cushion is segmented by introducing a notch that divides the cushion into distinct regions. This segmentation creates separate load paths: one through the notch region and another around it, allowing the sensor to detect different load distribution patterns that distinguish between child seats and adult occupants
Solution Approach 2:
The notch creates a localized region with different mechanical properties compared to the surrounding foam. This local modification changes how loads are transmitted through the cushion, creating a distinctive load signature for cinched-down child seats that differs from normally seated adults
2Measurement precision
If the sensor measures the distribution of occupant weight across the seat to distinguish between occupants, then accurate discrimination is possible, but the actual weight distribution cannot be accurately represented because the occupant weight disperses as it is transmitted through the foam seat cushion to the sensor
Solution Approach 1:
The notch acts as an intermediary structure that modifies the load transmission path between the occupant and the sensor. By creating a defined load path through the notch, it preserves information about the original weight distribution that would otherwise be lost due to foam dispersion
Solution Approach 2:
The notch segments the foam cushion to create distinct load transmission zones, allowing the sensor to detect differentiated load patterns that reflect the actual weight distribution characteristics of different occupant types
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 effectively discriminates between a normally seated adult and a cinched-down child seat of similar apparent weight, ensuring accurate detection and preventing unnecessary airbag deployment, while maintaining occupant comfort and reducing costs.
Implementation Method 1
measuring the fluid pressure in the bladder with a pressure-responsive sensor
Data Source
AI summary
A seat occupant sensing apparatus includes a notched foam bottom seat cushion and a pressure-responsive sensor disposed between the bottom cushion and a frame of the seat. The notch is a narrow channel on the underside of the foam cushion that extends upward into the foam to limit and direct dispersion of occupant loading through the cushion. A rectangular notch smaller in dimension than a child seat frame is formed in a central region of the foam cushion, and a fluid-filled bladder or other force-responsive sensor mat is disposed substantially within the perimeter of the notch. The sensor will detect a normally seated occupant due to the relatively uniform seat load, but will not detect a cinched-down child seat because the notch limits dispersion of child seat loading in the direction of the sensor.