Arousal Level Determination via Band-Pass Filtered Heartbeat Spectral Density
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Solution Overview
Problem
Existing arousal-level determining technologies face challenges in accurately determining subject arousal levels due to indistinct feature points calculated from heartbeat signals by frequency analysis.
Innovation Solution
An arousal-level determining apparatus that generates heartbeat-interval variation data, applies a band-pass filter to specific frequency bands, calculates spectral density, and identifies feature points corresponding to spectral density peaks to determine arousal levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency analysis is applied to heartbeat signals to determine arousal level, then arousal level can be determined, but feature points may become indistinct leading to determination failure
Solution Approach 1:
The patent divides the frequency spectrum into multiple frequency bands and applies band-pass filters to each band separately. This segmentation allows the system to isolate and enhance specific frequency components, making feature points more distinct and reliable for arousal level determination even when the overall spectral density shows indistinct peaks.
Solution Approach 2:
The patent enhances local quality by applying different band-pass filters to different frequency bands, allowing each band to be processed with optimized filtering parameters. This local processing improves the distinctness of feature points in specific frequency ranges that are most relevant to arousal level detection.
2Measurement precision
If band-pass filter is applied to each frequency band, then spectral density peaks become more distinct, but calculation complexity increases
Solution Approach 1:
The patent segments the frequency spectrum into multiple bands and applies band-pass filters to each segment. While this increases calculation steps, it enables more precise spectral density peak detection by focusing on specific frequency ranges, which is necessary for reliable arousal level determination.
Solution Approach 2:
The patent applies band-pass filtering to each frequency band, which is more processing than a single global filter would require. This excessive action in terms of computation ensures that spectral density peaks are sufficiently distinct for reliable feature point identification, trading calculation complexity for measurement precision.
Data Source
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AI summary
An arousal-level determining apparatus (100) includes a generating unit (120), a calculating unit (130), an identifying unit (140), and a determining unit (180). The generating unit (120) generates heartbeat-interval variation data, which indicates changes in heartbeat interval, on the basis of heartbeat signals indicating subject's heartbeats. The calculating unit (130) applies a band-pass filter, which allows passage of a certain range of frequencies, to each frequency band in the heartbeat-interval variation data while changing the frequency band, and calculates spectral density with respect to each frequency band applied with the band-pass filter. The identifying unit (140) identifies a feature point corresponding to a spectral density peak in the calculated spectral densities in the frequency bands. The determining unit (180) determines subject's arousal level on the basis of the identified feature point.