Physiological State Estimation via Hilbert Transform

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Solution Overview

Problem

Existing methods for estimating physiological states from biological signals lack accuracy.

Innovation Solution

A method involving the acquisition of brain waves and pulse waves, filtering in specific frequency bands, performing Hilbert transformation, calculating instantaneous values, and extracting features based on specific conditions to estimate physiological states with high accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional biological signal analysis methods are used, then the analysis can be performed, but the estimation accuracy of physiological state is insufficient

Engineering Contradiction:

Improvephysiological state estimation accuracyVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the physiological signal analysis into distinct frequency bands (alpha, beta, gamma for brain waves; LF, HF for pulse waves) and processes each band separately through Hilbert transformation. This segmentation allows extraction of specific instantaneous frequency and amplitude features from each band, improving estimation accuracy by focusing on relevant frequency components while managing complexity through structured processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from traditional time-domain or simple frequency-domain analysis to instantaneous frequency-domain analysis using Hilbert transformation. This dimensional change enables extraction of time-varying instantaneous frequency and amplitude features that capture dynamic physiological states more accurately, resolving the contradiction between accuracy and complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If simple feature extraction methods are used, then the processing is fast, but the physiological state estimation accuracy is low

Engineering Contradiction:

Improvephysiological state estimation accuracyVSAvoidprocessing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary Hilbert transformation and instantaneous frequency calculation on each frequency band before feature extraction. By pre-processing the signals to obtain instantaneous frequency and amplitude features, the system prepares optimized input data that accelerates subsequent physiological state estimation while maintaining high accuracy through band-specific feature extraction.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the analysis parameters from fixed frequency components to time-varying instantaneous frequency and amplitude. This parameter transformation allows the system to capture dynamic physiological variations more accurately while using efficient computational methods for instantaneous feature extraction, balancing accuracy and processing speed.

Inventive Principle:

Principle #35Parameter changes

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 accurate estimation of physiological states by correlating brain and pulse wave features, allowing for precise determination of physiological conditions.

Implementation Method 1

a filtering unit configured to filter the acquired brain waves and pulse waves in at least one predetermined frequency band

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Implementation Method 2

a transformation unit configured to perform Hilbert transformation on the brain waves and pulse waves filtered in the frequency band

Methodology Applied

Scientific EffectHilbert transformation:

Data Source

PatentUS20250204864A1Physiological state estimation system, physiological state estimation method, and non-transitory computer readable medium

Publication Date: 2025.06.26 TOYOTA JIDOSHA KK

AI summary

A physiological state estimation system according to this embodiment includes: a waveform information acquisition unit configured to acquire brain waves and pulse waves; a filtering unit configured to filter the acquired brain waves and pulse waves in at least one predetermined frequency band; a transformation unit configured to perform Hilbert transformation on the brain waves and pulse waves filtered in the frequency band; and an instantaneous value calculation unit configured to calculate instantaneous values including an instantaneous logarithmic amplitude corresponding to a logarithm of an amplitude term of a complex waveform equation obtained by performing Hilbert transformation, and an instantaneous frequency corresponding to a time differential value of a phase term of a complex waveform equation.