Pulse Measurement Device Rest State Detection
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Solution Overview
Problem
Devices that measure pulse rate by detecting pulsatory motion in subcutaneous blood vessels non-electrocardiographically face difficulties in accurately measuring pulse rates during exercise due to external disturbances from body acceleration and sensor movement, making it challenging to extract the pulse wave signal's cyclic fluctuations.
Innovation Solution
A pulse measurement device and method that convert the time-domain pulse wave signal into a frequency domain to determine if the subject is at rest by identifying a frequency range with intensity exceeding a threshold and calculating its ratio within a total frequency range, allowing for accurate measurement of the at-rest pulse rate, which serves as a reference for tracking pulse rate during exercise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If photoelectric detection is used to measure pulse rate during exercise, then non-electrocardiographic measurement is achieved, but measurement accuracy deteriorates due to external disturbances from body acceleration and sensor movement
Solution Approach 1:
The patent segments the frequency spectrum into multiple frequency components and analyzes the distribution of energy across these components. By dividing the frequency range and examining the proportion of energy in each segment, the system can distinguish between pulse-related frequency components and disturbance-related components, thereby maintaining measurement accuracy during exercise.
2Device complexity
If pulse wave signal analysis is performed in time domain, then simple signal processing is achieved, but difficulty in extracting cyclic fluctuations increases due to superimposed external disturbances
Solution Approach 1:
The patent transforms the pulse wave signal from the time domain to the frequency domain using Fourier transform. This dimensional change allows the system to analyze the signal in terms of frequency components rather than temporal variations, making it easier to identify and extract the cyclic fluctuations corresponding to the pulse rate even in the presence of external disturbances.
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 correct determination of whether the subject is at rest and measures the pulse rate accurately at rest, allowing for reliable tracking of pulse rate during exercise using the at-rest pulse rate as a reference.
Implementation Method 1
A device that measures a measurement subject's pulse rate by photoelectrically detecting pulsatory motion in a measurement subject's subcutaneous blood vessel using a photoelectric sensor
Data Source
AI summary
A pulse wave signal expressing a pulse is obtained by detecting a pulse of a measurement subject using a pulse wave sensor. The pulse wave signal is stored in a storage unit. A frequency spectrum of the pulse wave signal is found by converting the time-domain pulse wave signal stored in the storage unit into the frequency domain. It is determined whether or not the measurement subject is at rest by finding a frequency range, within a predetermined total frequency range the pulse rate of a person can take on, in which an intensity of a frequency component of the frequency spectrum exceeds a first threshold, and finding whether or not a ratio of the frequency range with respect to the total frequency range is less than a second threshold. A pulse rate from the point in time when the measurement subject has been determined to be at rest is found as the measurement subject's at-rest pulse rate.