Motion-Dependent Averaging for Physiological Metric Estimating
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Solution Overview
Problem
Existing physiological signal processing systems face challenges in accurately extracting physiological metrics due to noise sensitivity, particularly from motion and sunlight interference, which affects the accuracy of health and fitness monitoring.
Innovation Solution
Incorporating a physiological metric extractor with an averager that has an impulse response responsive to motion signals, allowing for adaptive averaging window sizes based on motion signal strength, thereby improving noise rejection and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed averaging window size is used for physiological signal processing, then the device complexity is reduced, but the measurement precision deteriorates under varying motion conditions
Solution Approach 1:
The patent implements a dynamic averaging window size that automatically adjusts based on detected motion levels. During high motion periods, the window size decreases to provide faster response and reduce motion artifacts. During low motion periods, the window size increases to improve signal smoothing and measurement accuracy. This dynamic adaptation resolves the contradiction by making the processing complexity worthwhile only when needed for precision.
Solution Approach 2:
The system changes the temporal parameter (averaging window size) of the signal processing based on motion detection thresholds. When motion exceeds a threshold, the system switches to a shorter averaging window; when motion is below the threshold, it uses a longer averaging window. This parameter adaptation allows the system to optimize measurement precision across different activity states without requiring permanently complex processing.
2Reliability
If motion signals are completely filtered out, then noise rejection is improved, but loss of information occurs regarding actual physiological changes
Solution Approach 1:
The patent applies different processing qualities to different segments of the signal based on local motion conditions. During high-motion segments, aggressive filtering is applied to reject noise. During low-motion segments, minimal filtering is applied to preserve physiological information. This local adaptation of filtering strength resolves the contradiction by applying noise rejection only where needed without sacrificing overall signal information.
Solution Approach 2:
The filtering strength dynamically adapts to motion levels rather than using a fixed filter. The system modulates the degree of signal averaging based on real-time motion detection, allowing it to be more aggressive during motion and more conservative during rest. This dynamic approach preserves physiological information that would otherwise be filtered out by static filtering methods.
Data Source
AI summary
Physiological signal processing systems include a photoplethysmograph (PPG) sensor that is configured to generate a physiological waveform, and an inertial sensor that is configured to generate a motion signal. A physiological metric extractor is configured to extract a physiological metric from the physiological waveform that is generated by the PPG sensor. The physiological metric extractor includes an averager that has an impulse response that is responsive to the strength of the motion signal. Related methods are also described.


