Millimeter-Wave Radar Heartbeat Tracking with Adaptive Kalman Filtering
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Solution Overview
Problem
Existing radar systems face challenges in accurately and efficiently tracking vital signs, such as heartbeat rates, due to the small amplitude of heartbeat signals being overshadowed by larger movements and noise, particularly in environments with random body movements.
Innovation Solution
A method and device utilizing a millimeter-wave radar system with a bandpass filter to generate a displacement signal, followed by a Kalman filter to track and update the heartbeat rate, and adaptively adjust the bandpass filter settings based on the Kalman filter's track, effectively filtering out noise and stabilizing heartbeat rate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bandpass filter is used to extract heartbeat signals from radar displacement data, then the heartbeat rate can be determined, but the small amplitude heartbeat signals are overshadowed by larger movements and noise
Solution Approach 1:
The bandpass filter parameters (center frequency and bandwidth) are dynamically adjusted based on the tracked heartbeat rate from the Kalman filter, allowing the filter to adapt to changing heartbeat conditions and maintain optimal signal extraction performance
Solution Approach 2:
The Kalman filter provides feedback by tracking the heartbeat rate over time and using this information to update the bandpass filter settings, creating a closed-loop system that continuously optimizes signal extraction while filtering out noise and random movements
2Measurement precision
If the bandpass filter range is narrowed to improve heartbeat frequency precision, then measurement accuracy improves, but the filter may exclude valid heartbeat signals with frequency variations
Solution Approach 1:
The filter transition bandwidth is set to a dynamic value that adapts to the tracked heartbeat rate, allowing the filter to maintain precise frequency selection while accommodating natural variations in heartbeat frequency through the adaptive tracking mechanism
3Reliability
If a Kalman filter is used to track heartbeat rate over time, then stability and accuracy improve, but computational complexity increases
Solution Approach 1:
The Kalman filter uses a simplified state model that tracks only the heartbeat rate parameter, reducing computational complexity while maintaining tracking stability through efficient parameter estimation and prediction
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 system achieves high accuracy in heartbeat rate determination with minimal jumps, even in the presence of random body movements, by adaptively narrowing the bandpass filter range and centering it on the heartbeat frequency, thus improving the precision and stability of vital sign monitoring.
Implementation Method 1
transmitting a frequency modulated signal, receiving a reflection of the frequency modulated signal (also referred to as the echo), and determining a distance based on a time delay and/or frequency difference between the transmission and reception
Implementation Method 2
determining a distance based on a time delay and/or frequency difference between the transmission and reception of the frequency modulated signal
Data Source
Figure 1~3
Figure 2
Figure 4A~4B
AI summary
In an embodiment, a method includes: receiving reflected radar signals with a millimeter-wave radar; generating a displacement signal indicative of a displacement of a target based on the reflected radar signals; filtering the displacement signal using a bandpass filter to generate a filtered displacement signal; determining a first rate indicative of a heartbeat rate of the target based on the filtered displacement signal; tracking a second rate indicative of the heartbeat rate of the target with a track using a Kalman filter; updating the track based on the first rate; and updating a setting of the bandpass filter based on the updated track.