Radar vital signal tracking using a Kalman filter

Patent metadata

Field	Value
Publication number	US-11614516-B2
Application number	US-202016794904-A
Country	US
Kind code	B2
Filing date	Feb 19, 2020
Priority date	Feb 19, 2020
Publication date	Mar 28, 2023
Grant date	Mar 28, 2023

Abstract

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.

First claim

What is claimed is:

1. A method comprising:
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;
determining a gating region using a gating function;
updating the track when the first rate is inside the gating region; and
updating a setting of the bandpass filter to narrow a pass-band of the bandpass filter based on the updated track.

2. The method of claim 1 , wherein the displacement signal is a time-domain signal.

3. The method of claim 1 , wherein the gating function is an ellipsoidal gating function.

4. The method of claim 1 , further comprising:
incrementing a counter when the first rate is outside the gating region; and
increasing the pass-band of the bandpass filter when the counter reaches a count of M, wherein M is a positive integer greater than 1.

5. The method of claim 4 , wherein increasing the pass-band of the bandpass filter comprises increasing the pass-band based on the track.

6. The method of claim 1 , wherein updating the setting of the bandpass filter based on the updated track comprises adjusting a lower cutoff frequency of the bandpass filter or a higher cutoff frequency of the bandpass filter based on an uncertainty value associated with the updated track.

7. The method of claim 1 , wherein updating the setting of the bandpass filter based on the updated track comprises adjusting a center frequency of the bandpass filter.

8. The method of claim 1 , wherein the bandpass filter has an initial pass-band from 0.7 Hz to 3 Hz.

9. The method of claim 1 , wherein generating the displacement signal comprises:
generating range data based on the reflected radar signals;
performing target detection based on the range data to detect the target; and
generating the displacement signal based on in-phase (I) and quadrature (Q) signals associated with the detected target.

10. The method of claim 9 , wherein the range data corresponds to a range-Doppler image or a range cross-range image.

11. The method of claim 9 , wherein performing target detection comprises determining a target range bin, and wherein generating the displacement signal comprises generating the displacement signal when a standard deviation in the target range bin is below a predetermined threshold.

12. The method of claim 1 , wherein estimating the first rate comprises counting peaks in the filtered displacement signal.

13. The method of claim 1 , wherein the target is a human target.

14. The method of claim 1 , further comprising transmitting radar signals with the millimeter-wave radar, wherein the transmitted radar signals comprise linear chirps.

15. A device comprising:
a millimeter-wave radar configured to transmit chirps and receive reflected chirps; and
a processor configured to:
generate a displacement signal indicative of a displacement of a target based on the reflected chirps,
filter the displacement signal using a bandpass filter to generate a filtered displacement signal,
determine a first rate indicative of a heartbeat rate of the target based on the filtered displacement signal,
track a second rate indicative of the heartbeat rate of the target with a track using a Kalman filter,
determine a gating region using a gating function,
update the track when the first rate is inside the gating region, and
update a setting of the bandpass filter to narrow a pass-band of the bandpass filter based on the updated track.

16. The device of claim 15 , wherein the millimeter-wave radar comprises the processor.

17. The device of claim 15 , wherein updating the setting of the bandpass filter based on the updated track comprises adjusting a lower cutoff frequency of the bandpass filter or a higher cutoff frequency of the bandpass filter based on an uncertainty value associated with the updated track.

18. A method for tracking a vital rate indicative of a heartbeat rate of a human target using a track of a Kalman filter, the method comprising:
receiving reflected radar signals;
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;
generating a heartbeat rate estimate based on the filtered displacement signal;
determining a heartbeat rate prediction and an uncertainty prediction based on the track;
determining whether the heartbeat rate estimate is an outlier based on the uncertainty prediction; and
when the heartbeat rate estimate is determined to be not an outlier,
updating the track based on the heartbeat rate estimate, and
adjusting a lower cutoff frequency of the bandpass filter or a higher cutoff frequency the bandpass filter based on the uncertainty prediction.

19. A method for tracking a vital rate indicative of a heartbeat rate of a human target using a track of a Kalman filter, the method comprising:
receiving reflected radar signals;
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;
generating a heartbeat rate estimate based on the filtered displacement signal;
determining a heartbeat rate prediction and an uncertainty prediction based on the track:
determining a gating region using an ellipsoidal gating function based on the uncertainty prediction;
determining that the heartbeat rate estimate is an outlier when a result of the ellipsoidal gating function is higher than a predetermined threshold;
determining that the heartbeat rate estimate is not an outlier when the result of the ellipsoidal gating function is lower than the predetermined threshold; and
when the heartbeat rate estimate is determined to be not an outlier,
updating the track based on the heartbeat rate estimate, and
updating a setting of the bandpass filter based on the updated track.

20. A method for tracking a vital rate indicative of a heartbeat rate of a human target using a track of a Kalman filter, the method comprising:
receiving reflected radar signals;
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;
generating a heartbeat rate estimate based on the filtered displacement signal;
determining a heartbeat rate prediction and an uncertainty prediction based on the track;
determining whether the heartbeat rate estimate is an outlier based on the uncertainty prediction;
when the heartbeat rate estimate is determined to be not an outlier,
updating the track based on the heartbeat rate estimate, and
updating a setting of the bandpass filter based on the updated track; and

when the heartbeat rate estimate is determined to be an outlier:
incrementing a counter, and
increasing a pass-band of the bandpass filter when the counter reaches a count of M, wherein M is a positive integer greater than 1.

Assignees

• Infineon Technologies Ag

Inventors

• Santra Avik
• Arsalan Muhammad
• Will Christoph

Classifications

• A61B5/72

  Signal processing specially adapted for physiological signals or for diagnostic purposes · CPC title

• A61B5/02444

  Details of sensor (A61B5/02427 takes precedence) · CPC title

• A61B5/024

  Measuring pulse rate or heart rate · CPC title

• G01S13/88 Primary

  Radar or analogous systems specially adapted for specific applications (electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00) · CPC title

• G01S13/723

  by using numerical data · CPC title