Seat Cushion Pressure Sensing Matrix for Reliable Occupant Weight Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pressure sensing systems in vehicle seats have limited resolution due to the size and number of sensors, leading to unreliable weight measurements of occupants, especially when they shift or sit out of normal positions.
Innovation Solution
A pressure sensing system with a layer of electrically conductive foam and a flexible printed circuit, where horizontal and vertical sensing wires intersect to form multiple intersections, each acting as a pressure sensor, providing improved resolution and integration within the seat cushion to reduce mechanical stress and aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pressure sensors are used in vehicle seats, then weight sensing is provided, but the sensing resolution is low due to limited number and size of sensors
Solution Approach 1:
The patent segments the sensing function into multiple intersections formed by horizontal and vertical sensing wires within the foam structure. Each intersection acts as an independent sensing point, creating a grid pattern that provides high-resolution weight distribution data across the seat surface without requiring discrete sensor components.
Solution Approach 2:
The patent transitions from traditional point-based sensors to a two-dimensional grid network of sensing wires embedded in the foam. This dimensional expansion allows simultaneous measurement at multiple locations across the seat surface, dramatically improving spatial resolution and weight distribution detection capability.
2Reliability
If sensors are placed on the seat surface, then weight measurement is enabled, but the sensed weight is unreliable when occupant shifts or sits out of normal positions
Solution Approach 1:
The patent merges the sensing wires directly into the foam structure through integration, creating a unified sensing matrix that moves with the foam. This integration ensures that the sensing points maintain their relative positions and continue to accurately detect weight distribution regardless of occupant position changes or seat compression.
Solution Approach 2:
The patent utilizes changes in electrical properties (capacitance, resistance, or inductance) of the sensing wires at each intersection in response to foam compression. These parameter changes directly correlate with applied pressure, enabling reliable weight measurement that adapts to varying occupant positions and weights.
3Measurement precision
If multiple sensors are added to improve resolution, then sensing accuracy improves, but mechanical stress and aging of the flexible circuit increases
Solution Approach 1:
The patent replaces traditional mechanical pressure sensors with an electrical field-based sensing system using conductive or capacitive wire intersections. This substitution eliminates mechanical contact and friction at sensing points, significantly reducing mechanical stress on the flexible circuit and extending its operational lifespan while maintaining high sensing resolution.
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 system achieves higher sensing resolution and reliability in measuring occupant weight and distribution by generating real-time electric flux density values at each intersection, enhancing the accuracy of weight classification and airbag deployment decisions.
Implementation Method 1
each intersection generates in real time an electric flux density value to reflect a degree of a compression caused by the pressure
Data Source
AI summary
A pressure sensing system, seat cushion incorporating the pressure sensing system, and method of sensing a weight group associated with an occupant of an automotive seat are described. The pressure sensing system includes a layer of an electrically conductive foam and a flexible printed circuit that includes a flexible substrate and N horizontal sensing wires and M vertical sensing wires securely placed on a top surface of the flexible substrate. The horizontal sensing wires intersect with the vertical sensing wires and form (N×M) intersections. The layer of an electrically conductive foam is placed on top of the N horizontal sensing wires and the M vertical sensing wires. When a pressure is applied to the layer of the electrically conductive foam, each intersection generates in real time an electric flux density value to reflect a degree of a compression caused by the pressure to a corresponding point of the electrically conductive foam.