Adaptive Heartbeat Sensor Filter for Motion Noise
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Solution Overview
Problem
Existing heartbeat detection systems face reduced accuracy due to body motion noise components interfering with heartbeat signals, especially during exercise or activity, as the bandpass filter characteristics are not adequately adjusted for varying heart rates.
Innovation Solution
A sensor information processing apparatus that includes a receiver and processor to control the target frequency band of the heartbeat sensor signal based on inertial sensor data, adaptively adjusting the bandpass filter characteristics to improve detection accuracy by estimating heart rate from inertial sensor data and filtering out noise components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed bandpass filter is used for heartbeat detection, then the device structure is simple, but the detection accuracy deteriorates when heart rate varies or body motion occurs
Solution Approach 1:
The bandpass filter characteristics are made dynamic by automatically adjusting the passband width based on the detected heart rate. The filter transitions from a fixed configuration to a variable one, where the passband width adapts to different heart rates, thereby maintaining high detection accuracy across varying physiological conditions without requiring complex manual intervention
Solution Approach 2:
A feedback mechanism is implemented where the heart rate detection result is fed back to the filter control unit, which then adjusts the passband width accordingly. This closed-loop control ensures that the filter characteristics continuously adapt to the current heart rate, resolving the contradiction between simple structure and accurate detection under varying conditions
2Adaptability or versatility
If the passband width is widened to include variable heart rates, then the adaptability improves, but noise components from body motion are not adequately filtered
Solution Approach 1:
The passband width is dynamically adjusted based on the detected heart rate rather than being fixed. When heart rate is high, the passband width is appropriately widened to capture the faster heartbeat signals, while when heart rate is low, the passband width is narrowed to effectively filter out body motion noise. This dynamic adaptation resolves the contradiction between covering variable heart rates and filtering noise
Solution Approach 2:
The filter parameter (passband width) is changed according to the heart rate parameter. By establishing a relationship between heart rate and optimal passband width, the system automatically selects appropriate filter parameters for different physiological states, achieving both adaptability to varying heart rates and effective noise rejection
3Object-affected harmful factors
If the passband width is narrowed to filter noise, then the noise rejection improves, but heartbeat signals at varying rates may be lost
Solution Approach 1:
The passband width is made dynamic rather than fixed, allowing it to expand or contract based on the detected heart rate. This ensures that heartbeat signals across varying rates are captured while maintaining narrow bandwidth when appropriate to filter noise, thereby resolving the contradiction between noise rejection and signal coverage
Solution Approach 2:
The system uses feedback from heart rate detection to control the passband width. When a heartbeat signal is detected, the passband width is adjusted to include that frequency range, ensuring the signal is not lost. This feedback mechanism ensures the filter adapts to capture varying heart rates while maintaining noise filtering effectiveness
Data Source
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AI summary
A target frequency band to be processed in a detected signal of a heartbeat sensor (21) is controlled according to a detected signal of an inertial sensor (22).