Heartbeat Interval Detection Using Adaptive Frequency Filtering
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Solution Overview
Problem
Existing biological information detection methods struggle with low accuracy due to noise interference and insufficient signal intensity, particularly near the fundamental frequency, making it difficult to accurately detect heartbeats.
Innovation Solution
A biological information detection device that includes a pneumatic sensor to detect body motion, a frequency analysis unit, a filter processing unit, and a detection unit to estimate fundamental frequency, apply bandpass filters, and detect heartbeat intervals based on peak detection and correction, even in low SN ratio conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bandpass filter is applied to extract heartbeat signals from body motion detection, then the heartbeat signal can be extracted from the detection signal, but when noise is superimposed on the harmonic band or when signal intensity is insufficient, the signal-to-noise ratio deteriorates and detection accuracy decreases
Solution Approach 1:
The patent performs preliminary frequency analysis on the detection signal before applying the bandpass filter. By analyzing the frequency characteristics in advance and identifying the fundamental frequency and harmonic components, the system can set the filter parameters more accurately. This preliminary action ensures that the filter is configured to pass the actual heartbeat signal frequencies while rejecting noise, thereby maintaining high signal-to-noise ratio and detection accuracy even in noisy environments
Solution Approach 2:
The patent dynamically adjusts the bandpass filter parameters based on the frequency analysis results. Instead of using fixed filter parameters, the system changes the passband frequencies and bandwidth according to the detected fundamental frequency and its harmonics. This parameter adaptation allows the filter to track the heartbeat signal characteristics and maintain optimal signal-to-noise ratio across varying physiological conditions and noise levels
2Measurement precision
If noise is superimposed near the fundamental frequency, then the fundamental frequency cannot be correctly estimated, but frequency analysis is performed to generate the filter
Solution Approach 1:
The patent uses harmonic components as intermediaries to estimate the fundamental frequency when direct estimation from the fundamental frequency region is unreliable due to noise. By detecting the harmonic frequencies (which are integer multiples of the fundamental frequency) and working backwards to calculate the fundamental frequency, the system can accurately determine the heartbeat rate even when the fundamental frequency region is contaminated by noise. The harmonics serve as reliable mediators that preserve the fundamental frequency information
Solution Approach 2:
The patent implements a feedback mechanism where the frequency analysis results are used to adjust the filter parameters, and the filter output is further analyzed to refine the fundamental frequency estimation. The system continuously monitors the detection signal, performs frequency analysis, adjusts the bandpass filter accordingly, and uses the filtered signal to re-estimate the fundamental frequency. This iterative feedback process improves the accuracy of fundamental frequency estimation by leveraging information from both the raw and filtered signals
Data Source
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AI summary
A biological information detection device (111) includes: a sensor (12) configured to detect information on a body motion of a person; a frequency analysis unit (202) configured to perform frequency analysis on a detection signal of the information on the body motion detected by the sensor; a filter processing unit (205) configured to generate a filter based on a result of the frequency analysis and apply the generated filter to the detection signal; and a detection unit (206) configured to detect biological information that is a heartbeat interval based on a detection signal before applying the filter corresponding to a peak of a detection signal after applying the filter.