Vehicle Seat Occupant Classification via Merged Weight and Capacitive Sensing
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Solution Overview
Problem
Current occupant classification systems in vehicles, relying on capacitive sensing and seat weight rail systems, fail to accurately distinguish between different types of occupants, particularly in the 'grey zones' between small and large classifications, leading to unreliable safety protocols and air bag deployment decisions.
Innovation Solution
A system utilizing a pair of occupant classification sensors with sensing and shield electrodes, coupled to a controller that configures the sensors into various circuit configurations to measure changes in current characteristics, providing output signals used to identify occupant classifications based on threshold boundaries in a coordinate system, integrating weight and capacitive sensing for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacitive sensing systems are used for occupant classification, then the system structure is simple, but the measurement precision is insufficient to accurately distinguish between different occupant types in grey zones
Solution Approach 1:
The patent combines weight sensing and capacitive sensing into a single integrated sensor assembly. The sensor includes both a weight sensing element (such as a load cell or strain gauge) and a capacitive sensing element (such as a capacitive sensor or electric field sensor) positioned in close proximity to each other, allowing simultaneous measurement of both weight and capacitive properties of the occupant. This merging approach improves measurement precision for occupant classification while avoiding the complexity of separate independent sensing systems.
Solution Approach 2:
The sensor assembly is designed to perform multiple functions: it can detect occupant presence, determine occupant weight, classify occupant type (adult, child, infant), and distinguish between different seating positions. By integrating multiple sensing capabilities into a single device, the system achieves high measurement precision across multiple parameters without proportionally increasing system complexity.
2Measurement precision
If seat weight rail systems are used for occupant detection, then weight measurement is provided, but the system cannot reliably distinguish between different types of occupants leading to false detections
Solution Approach 1:
The patent merges weight sensing and capacitive sensing capabilities into an integrated sensor system. The weight sensing element measures the mass of the occupant while the capacitive sensing element measures electrical properties such as capacitance or impedance. By combining these measurements, the system can differentiate between occupant types (adult, child, infant) and seating positions with high reliability, eliminating false detections that occur with weight-only systems.
Solution Approach 2:
The system utilizes changes in multiple parameters (weight and capacitive properties) to classify occupants. Different occupant types exhibit distinct combinations of weight and capacitive characteristics. By monitoring and analyzing these parameter changes simultaneously, the system achieves reliable occupant type differentiation and improves the reliability of safety protocols such as airbag deployment decisions.
3Measurement precision
If multiple sensing circuits with different configurations are used, then occupant classification accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple sensing circuits into a single integrated sensor assembly. The weight sensing element and capacitive sensing element are positioned in close proximity and can be electrically connected to form a unified sensing system. This merging approach allows the system to utilize multiple circuit configurations (such as differential weight measurement and capacitive measurement modes) while maintaining a compact, integrated device structure rather than requiring separate independent sensing systems.
Solution Approach 2:
The integrated sensor assembly is designed to perform multiple sensing functions through different circuit configurations. The same physical sensor structure can operate in weight measurement mode, capacitive measurement mode, or combined measurement mode, depending on the circuit configuration activated. This multi-functionality allows the system to achieve high classification accuracy through multiple measurement approaches without proportionally increasing device 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 system provides enhanced occupant classification accuracy, effectively distinguishing between different weight categories, including infants, children, and adults, reducing false detections and improving safety protocols by minimizing grey zones in traditional classification systems.
Implementation Method 1
The sensing electrode and the shield electrode are electrically coupled to the sensing circuit. The sensing circuits corresponding to the at least one pair of sensing electrodes provide, to the controller, a respective output signal corresponding to a respective change in the sensing current on the respective sensing electrodes.
Implementation Method 2
The electric field sensor comprises at least one electrode located, for example, in the seat bottom under the seat cover and close to the top of a foam cushion, and adapted to enable a type of occupant or object that may be upon the seat bottom of the vehicle seat to be distinguished.
Data Source
AI summary
An occupant detection system includes a controller, a sensing electrode, and a shield electrode, the electrodes disposed in a vehicle seat. The controller is electrically coupled to the sensing electrode and shield electrode by a sensing circuit. The controller is configured to send an input signal to the sensing electrode, the shield electrode, or both and measures current, impedance, or capacitance values to determine the presence of an object on the seat, to classify the object, or both.