Seat Coil Array Calibration for In-Vehicle Vital Sign Sensing
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Solution Overview
Problem
Existing in-vehicle inductive sensing systems face challenges in accurately measuring vital signs such as heart rate and respiration rate due to variations in user height and posture, as the position of anatomical landmarks like the heart and lungs relative to the sensor array differs among individuals, requiring adaptive selection of coils and optimal drive signal characteristics.
Innovation Solution
An in-vehicle inductive sensing apparatus with a plurality of coils arranged in an array relative to a user-engaging surface, where the spatial arrangement of the coils is estimated based on inductive sensing signals to select the appropriate subset of coils for measuring vital signs, and drive signal characteristics are adjusted to optimize performance according to user dimensions and posture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed sensor array is integrated in the seat, then the device complexity is reduced and ease of operation is improved, but measurement precision deteriorates due to variations in user height and posture
Solution Approach 1:
The system dynamically selects which coils to use and adjusts drive signal characteristics based on real-time detection of user position and body dimensions. This dynamic adaptation allows the fixed sensor array to achieve variable precision measurements for different users without requiring physical reconfiguration of the sensor array itself.
Solution Approach 2:
The system changes operational parameters (coil selection subset and drive signal characteristics) based on detected user characteristics. By modifying these parameters according to user height and posture, the system maintains high measurement precision across different users while keeping the physical sensor array fixed and simple.
2Adaptability or versatility
If the sensor array is fixed relative to the seat, then ease of manufacture is improved, but adaptability deteriorates for users of different heights and postures
Solution Approach 1:
The system performs preliminary detection of user position and body dimensions before vital sign measurement begins. Based on this preliminary information, it pre-selects the appropriate coil subset and configures optimal drive signal characteristics, enabling the fixed sensor array to adapt to different users without requiring physical reconfiguration.
Solution Approach 2:
The system dynamically adjusts which coils are active and modifies drive signal parameters based on real-time user characteristics. This dynamic parameter adjustment provides versatility for different user dimensions while maintaining a simple, fixed physical sensor array that is easy to manufacture and integrate into the seat.
3Ease of operation
If additional hardware is required for vital sign measurement, then measurement precision is improved, but ease of operation deteriorates due to user actions required
Solution Approach 1:
The system uses a single integrated sensor array that serves multiple functions: detecting user position, determining body dimensions, and measuring vital signs. This multi-functionality eliminates the need for separate hardware components while maintaining measurement precision through intelligent signal processing and adaptive coil selection.
Solution Approach 2:
The system automatically detects user characteristics and configures itself without requiring user intervention. The sensor array self-adjusts by selecting appropriate coils and optimizing drive signals based on detected user position and body dimensions, providing passive measurement convenience while maintaining high precision.
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
Enables passive, non-contact measurement of vital signs without additional user equipment, improving convenience and accuracy by calibrating the sensor array to the user's specific anatomical position and dimensions, enhancing the reliability of biological parameter extraction.
Implementation Method 1
the oscillator drives the coil with an alternating current. When the coil is placed over the body-to-be-sensed, eddy currents are induced in the body, which cause inducement of secondary electromagnetic fields
Implementation Method 2
eddy currents are induced in the body, which cause inducement of secondary electromagnetic fields
Implementation Method 3
The changes in the complex impedance can be measured in practice through measurement of consequent detuning of resonance characteristics of the resonator circuit (e.g. the natural oscillation frequency and oscillation amplitude)
Data Source
AI summary
A method of calibrating an in-vehicle inductive sensing apparatus to the dimensions and/or posture of a user seated in the vehicle. An array of inductive sensing coils is mounted in a fixed position relative to a geometry of the seat in which the user is received. From the spatial pattern or distribution of inductive sensing signals, it is determined which subset of coils is positioned most appropriately, e.g. which is closest, to an anatomical body of interest. A biological measurement pertaining to the anatomical body of interest is computed using data from only the selected subset of coils.