Sleeping wake determination using load integration
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Solution Overview
Problem
Current systems for determining a subject's sleeping or waking state based on load detection are not precise enough, as they are influenced by body frame and short-duration body motions.
Innovation Solution
A sleeping/waking determining system that uses load detectors under a bed to calculate standard deviations and respiratory waveforms, normalizing these values by respiratory waveform amplitude to calculate an activity index, which integrates over time to differentiate between sleeping and waking states with higher precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If body motion number or standard deviation of body movement data is used for sleeping/waking determination, then the determination can be performed based on load detection, but the precision is reduced due to influence from body frame and short-duration body motions
Solution Approach 1:
The patent applies preliminary action by calculating the respiratory waveform and its amplitude before performing the sleeping/waking determination. The system first extracts respiratory information from the load detection data, then uses this respiratory waveform as a reference to normalize the activity index calculation. This preliminary extraction of respiratory characteristics allows the system to distinguish between respiratory movements and other body motions, thereby improving determination precision while eliminating the harmful influence of body frame variations and short-duration motions.
2Measurement precision
If simple body motion counting or standard deviation calculation is used, then the system complexity is reduced, but the determination precision deteriorates
Solution Approach 1:
The patent applies parameter changes by transforming the raw load detection data into a normalized activity index that is independent of body frame and respiratory amplitude variations. Instead of directly using body motion number or standard deviation, the system calculates the activity index by normalizing with respect to the respiratory waveform amplitude. This parameter transformation maintains relatively simple system structure while significantly improving determination precision by eliminating the influence of varying respiratory depths and body frame characteristics.
3Measurement precision
If normalization by respiratory waveform amplitude is performed, then the influence of respiratory depth variation is reduced, but the calculation complexity increases
Solution Approach 1:
The patent applies universality by making the respiratory waveform serve multiple functions: it is used both for monitoring the subject's respiratory state and as a normalization reference for the activity index calculation. The respiratory waveform extracted from load detection data performs dual purposes - characterizing respiratory patterns and providing the basis for eliminating respiratory amplitude effects from the activity assessment. This multi-functional use of the respiratory waveform reduces overall system complexity while improving precision under varying respiratory conditions.
Data Source
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AI summary
A sleeping/waking determining system (100) configured to determine whether a subject on a bed (BD) is in a sleeping state or in a waking state, includes: a load detector (11) configured to detect a load of the subject on the bed; and a determining unit (33) configured to determine whether the subject is in the sleeping state or in the waking state, based on a comparison between a threshold value and a value obtained by performing a time-integration of a standard deviation of a temporal variation of the load of the subject.