Physical Condition Detection via Heart Rate and Blood Pressure Gradient Analysis
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Solution Overview
Problem
Existing technologies are ineffective in detecting sudden changes in physical condition, such as those experienced while driving or after exercise, despite being able to detect changes in biological states like fatigue.
Innovation Solution
A physical condition determination device that analyzes biosignals from the dorsal body surface to detect sudden changes in heart rate and blood pressure, using frequency-gradient time-series waveforms and distribution ratios of specific frequency components to determine the occurrence of a sudden physical condition change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency analysis of biosignal is used to detect fatigue state, then detection of gradual physical condition changes is improved, but detection of sudden physical condition changes remains ineffective
Solution Approach 1:
The patent segments the detection process into two distinct analysis paths: one for gradual changes using frequency analysis of power spectra in ULF/VLF bands, and another for sudden changes using gradient analysis of time-series waveforms. This segmentation allows each method to optimize for its specific detection target, resolving the contradiction between detecting gradual and sudden physical condition changes.
Solution Approach 2:
The patent introduces dynamic threshold values for gradient magnitude that adapt based on the current state of the biosignal. By making the detection threshold dynamic rather than fixed, the system can respond appropriately to both gradual variations (using frequency analysis) and sudden changes (using gradient analysis with adaptive thresholds), thereby improving reliability for sudden change detection while maintaining accuracy for gradual changes.
2Measurement precision
If only frequency analysis of power spectra is used, then detection of fatigue progression is improved, but response time for sudden physical condition changes is delayed
Solution Approach 1:
The patent implements periodic calculation of gradient magnitudes at multiple time points within each analysis window. This periodic sampling approach allows the system to maintain continuous monitoring capability for sudden changes while still performing comprehensive frequency analysis for fatigue progression, thereby reducing response time without sacrificing measurement precision.
Solution Approach 2:
The patent performs preliminary gradient calculations on the time-series waveform before conducting full frequency analysis. By pre-processing the signal to identify potential sudden changes through gradient analysis, the system can trigger faster response for sudden physical condition changes while maintaining accurate fatigue progression detection through subsequent frequency analysis, thus reducing overall response time.
3Loss of information
If multiple frequency components are analyzed, then comprehensive physical state assessment is improved, but computational complexity increases
Solution Approach 1:
The patent extracts and analyzes only the specific frequency components relevant to physical condition assessment (ULF and VLF bands corresponding to 0.0017 Hz, 0.0035 Hz, and 0.0053 Hz). By extracting and focusing on these particular frequency components rather than analyzing the entire spectrum, the system maintains comprehensive physical state information while reducing computational complexity through targeted analysis.
Solution Approach 2:
The patent applies partial action by performing gradient analysis only when sudden changes are suspected (based on threshold comparisons), rather than continuously performing both gradient and frequency analysis at full computational intensity. This selective application of analysis methods reduces overall computational complexity while maintaining comprehensive monitoring capability when needed.
Data Source
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AI summary
The occurrence of a sudden change in physical condition is detected. In a physical condition determination device 100, a heart rate-relate index calculation unit 110 specifies an appearance time of a sign of a sudden change in heart rate, from a time-series waveform of an index corresponding to a variation in the heart rate (heart rate-related index) and a blood pressure-related index calculation unit 120 specifies an appearance time of a sign of a sudden change in blood pressure, from a time-series waveform of an index corresponding to a variation in the blood pressure (blood pressure-related index). A physical condition sudden change determination unit 130 determines that a sudden change in physical condition (physical condition sudden change) has occurred in a case where these appearance times are both within a predetermined time. This enables the determination in which the sudden change in the heart rate and the sudden change in the blood pressure are taken into consideration, to enable the detection of the physical condition sudden change.