Vehicle Occupant Classification via Impedance Measurement

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Solution Overview

Problem

Existing occupant classification systems for vehicles face challenges in robustly classifying objects on seats due to electromagnetic wave interference and changes in the surrounding environment, which affect the accuracy of pressure distribution measurements.

Innovation Solution

An occupant classification apparatus that uses a sensor mat with overlapping electrodes to measure impedance via Fourier transform, periodically adjusts the gain and frequency of power to mitigate interference and noise, and employs a controller to analyze the measured current and estimate the object's type based on impedance values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pressure distribution measurement is used for occupant classification, then the system can monitor passenger state, but the measurement accuracy deteriorates due to electromagnetic wave interference and environmental changes

Engineering Contradiction:

Improveoccupant classification accuracyVSAvoidelectromagnetic wave interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical pressure distribution measurement system with an electrical impedance measurement system. The sensor mat uses electrical electrodes to measure impedance changes caused by occupant contact, substituting mechanical pressure sensing with electrical field-based detection that is less susceptible to electromagnetic interference and environmental changes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from mechanical pressure to electrical impedance. By measuring impedance changes in the sensor mat electrodes rather than mechanical pressure distribution, the system achieves more stable and accurate occupant classification that is resistant to electromagnetic wave interference and environmental variations.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If Fourier transform is used to measure impedance, then the system can accurately classify objects on seats, but the device complexity increases

Engineering Contradiction:

Improveimpedance measurement accuracyVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies signal processing substitution by replacing complex mechanical measurement systems with electrical impedance measurement combined with Fourier transform analysis. The Fourier transform converts time-domain impedance signals into frequency-domain representations, enabling accurate object classification through spectral analysis while maintaining manageable system complexity through standard signal processing techniques.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If gain and frequency are periodically adjusted to mitigate interference, then the system robustness improves, but the operation complexity increases

Engineering Contradiction:

Improvesystem robustness against interferenceVSAvoidcontrol operation simplicity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent implements periodic adjustment of gain and frequency parameters in the signal processing chain. By periodically recalibrating these parameters, the system maintains optimal performance and robustness against electromagnetic interference and environmental changes, while the automated periodic nature of the adjustment keeps operational complexity manageable.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system employs feedback mechanisms to monitor signal quality and automatically adjust gain and frequency parameters. This closed-loop control ensures the system maintains high reliability and robustness against interference, while the automated feedback-based adjustment reduces manual intervention and operational complexity.

Inventive Principle:

Principle #23Feedback

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 effectively classifies objects on seats by accurately measuring impedance and distinguishing between different types of objects, even in the presence of electromagnetic wave interference and environmental changes, ensuring reliable operation and robustness against noise.

Implementation Method 1

measure a current based on impedance of the object using the sensor mat

Methodology Applied

Scientific EffectImpedance measurement: Electrical Resistance

Implementation Method 2

operator configured to convert a signal measured by the measurer into a frequency domain by Fourier transform

Methodology Applied

Scientific EffectFourier transform:

Data Source

PatentUS10532713B2Occupant classification apparatus for vehicle

Publication Date: 2020.01.14 HYUNDAI MOTOR CO LTD

AI summary

The present invention provides an occupant classification apparatus for a vehicle. The occupant classification apparatus for a vehicle includes a sensor mat that is mounted on each seat in the vehicle to sense objects disposed on the seats. An impedance measurer is configured to measure a current based on impedance of the object using the sensor mat A controller is configured to analyze the current measured by the impedance measurer and estimate the object that corresponds to the analyzed result.