Radar Heart Rate Measurement with Adaptive Harmonics Filtering
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Solution Overview
Problem
Current methods for monitoring physiological responses in laboratory animals, such as heart rate and respiratory rate, often require invasive sensors, which can cause unintended effects or death, and non-invasive methods like electrocardiography are not suitable for non-contact monitoring.
Innovation Solution
A non-invasive method using a harmonics comb notch digital filter (HCNDF) to filter cardiorespiratory motion data, adjusting notch depths based on respiration displacement, and identifying heart rate from filtered data, utilizing a 60 GHz radar for non-contact measurement of vital signs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact sensors such as electrocardiography are used for physiological monitoring, then measurement precision is improved, but animal welfare deteriorates due to surgical implantation requirements
Solution Approach 1:
The patent replaces contact-based mechanical/electrical sensing systems (ECG electrodes requiring surgical implantation) with a radar-based electromagnetic sensing system. The radar system uses electromagnetic waves to detect cardiorespiratory motion non-invasively, eliminating the need for surgical implantation while maintaining measurement capability through Doppler frequency shift analysis of reflected signals.
Solution Approach 2:
The patent introduces radar electromagnetic waves as an intermediary medium to indirectly measure physiological parameters. Instead of direct contact with the animal's body, the radar waves serve as a mediator that reflects off the animal's chest wall motion, allowing heart rate and respiratory rate measurement without physical intrusion or surgical intervention.
2Object-affected harmful factors
If radar is used for non-contact measurement, then animal welfare is improved by eliminating surgical implants, but measurement precision deteriorates due to respiration harmonics interference
Solution Approach 1:
The patent extracts and removes the harmful respiration harmonics components from the radar signal spectrum. By identifying the fundamental respiration frequency and its harmonic multiples, the system selectively eliminates these interfering components through spectral filtering, isolating the heart rate signal that would otherwise be obscured by the stronger respiration-related harmonics.
Solution Approach 2:
The patent converts the harmful respiration harmonics into a beneficial diagnostic tool. By analyzing the spectral structure and identifying harmonic patterns, the system uses the presence and characteristics of respiration harmonics to automatically adjust filter parameters and optimize heart rate detection, turning what was previously pure interference into a useful reference for signal processing.
3Measurement precision
If adaptive filtering is applied to remove respiration harmonics, then heart rate identification accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-adjusting filtering system that automatically determines its own parameters without external intervention. The algorithm autonomously identifies the respiration fundamental frequency from the spectral content, calculates the appropriate notch frequencies and depths based on detected harmonic patterns, and dynamically configures the filter settings in real-time, eliminating the need for manual filter tuning or complex user configuration.
Solution Approach 2:
The patent employs feedback mechanisms where the detected spectral characteristics continuously inform filter parameter adjustments. The system monitors the radar signal spectrum, identifies respiration harmonics, and uses this information to adaptively modify the notch filter settings, creating a closed-loop control system that optimizes heart rate extraction based on real-time signal conditions.
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 accurate and non-invasive measurement of heart rate and respiratory rate in laboratory animals without the need for surgical implants, providing reliable data for drug efficacy studies and ensuring animal welfare.
Implementation Method 1
A Doppler radar transceiver can be configured to transmit a single-tone carrier signal and receive a cardiorespiratory motion signal reflected from a monitored subject
Data Source
AI summary
Various examples are provided for accurate heart rate measurement. In one example, a method includes determining respiration displacement from radar-measured cardiorespiratory motion data; adjusting notch depths of a data filter based upon the respiration displacement; and identifying a heart rate from data filtered by the data filter. In another example, a system includes a computing device that can determine a respiration displacement from radar-measured cardiorespiratory motion data; wherein the computing device can adjust a data filter based upon the respiration displacement; and can identify a heart rate based on data filtered by the data filter.