Breathing Detection Using Zero-Crossing Analysis
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Solution Overview
Problem
Existing radar systems for breathing detection and monitoring are not robust to movement of subjects, irregular breathing patterns, or fast breathing rate variations, and they have high complexity due to processing demands.
Innovation Solution
A method and system for breathing detection and monitoring that involves receiving signals, generating a channel impulse response, selecting a portion of the response, removing clutter, generating regression lines, computing zero-crossing times, and estimating breathing rate based on these times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency analysis methods are used for breathing detection, then breathing rate estimation can be obtained, but the system becomes complex and computationally demanding
Solution Approach 1:
The patent extracts only the essential feature needed for breathing detection - the periodic variation in channel impulse response taps - and applies a simplified zero-crossing detection method instead of full frequency analysis. This extracts the breathing signal from the complex radar return by focusing only on the periodic distance variations of the chest wall, eliminating the need for computationally intensive Fourier transforms or wavelet analysis while maintaining detection accuracy
Solution Approach 2:
The patent changes the detection parameter from frequency domain analysis to time domain zero-crossing detection. Instead of transforming the signal to frequency domain and analyzing spectral peaks, the method detects zero-crossings of the differentiated channel impulse response, which directly corresponds to the periodic breathing motion. This parameter change simplifies the computational requirements while preserving the ability to estimate breathing rate
2Measurement precision
If frequency analysis methods are used for breathing detection, then breathing rate can be estimated, but the system is not robust to subject movement or irregular breathing patterns
Solution Approach 1:
The patent implements a dynamic tracking approach where the breathing rate estimation is continuously updated by detecting zero-crossings in real-time. The method dynamically adapts to changing breathing patterns and subject movement by continuously monitoring the periodicity of chest wall motion rather than relying on fixed frequency assumptions. This dynamic approach allows the system to track breathing rate variations and maintain robustness against movement artifacts
Solution Approach 2:
The system employs feedback through continuous monitoring and tracking of zero-crossing times. By continuously comparing the detected periodicity against expected breathing patterns and adjusting the estimation accordingly, the system provides feedback-driven adaptation to irregular breathing patterns and movement. The tracking mechanism uses the detected periodic variations to continuously refine the breathing rate estimation, making the system more reliable under varying conditions
3Measurement precision
If traditional frequency transform methods are used, then breathing detection can be performed, but resource consumption is high
Solution Approach 1:
The patent replaces expensive, computationally intensive frequency transform operations with a cheap, simple zero-crossing detection algorithm. Instead of performing full Fourier transforms or wavelet decompositions that require significant computational resources, the method uses simple threshold-based zero-crossing detection on the differentiated channel impulse response. This disposable-like approach uses minimal computational resources while maintaining the essential breathing detection functionality
Solution Approach 2:
The patent substitutes the mechanical/computational complexity of frequency domain transformation with a simpler time domain operation. Rather than mechanically performing complex mathematical transforms, the system uses direct time domain differentiation and zero-crossing detection, which are computationally much lighter operations. This substitution dramatically reduces processor requirements and energy consumption while preserving the core detection capability
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
The proposed method and system are more robust to irregularities in breathing patterns due to subject movement and can adapt quickly to changes, while also reducing resource consumption compared to traditional frequency transform-based techniques.
Implementation Method 1
Radar systems, including ultra-wideband-based radars, can be used to sense the environment by providing a means of obtaining propagation channel measures. The propagation channel is due to the reflections of the transmitted signal on the environment.
Implementation Method 2
The propagation channel is due to the reflections of the transmitted signal on the environment. Each CIRE's complex components (taps) corresponds to a propagation delay of the reflected signal and thus to a reflecting target's distance.
Data Source
AI summary
Embodiments of the present disclosure include methods, systems, and devices for breathing detection and monitoring comprising: receiving, via a data interface, a first parameter; receiving, via a receiver, a plurality of signals; generating a channel impulse response from the plurality of signals; selecting a portion of the channel impulse response based on the first parameter; generating a modified signal from the portion of the channel impulse response, wherein the modified signal is the portion of the channel impulse response with clutter removed; generating a plurality of regression lines from the modified signal; computing a plurality of times based on the plurality of regression lines, wherein each of the plurality of regression lines goes through zero at one of the plurality of times; estimating a zero-crossing time based on the plurality of times; and generating a breathing rate estimation based on the zero-crossing time.