WEARABLE HEART RATE MONITOR

• US 20140275854A1
• Filed: 06/03/2014
• Published: 09/18/2014
• Est. Priority Date: 06/22/2012
• Status: Active Grant

• Current Assignee: Fitbit, Inc. (Alphabet Inc.)
• Original Assignee: Fitbit, Inc. (Alphabet Inc.)
• Inventors: Venkatraman, Subramaniam, Yuen, Shelten Gee Jao
• Granted Patent: US 8,998,815 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/1123 Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6831 Straps, bands or harnesses
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence

Abstract

A biometric monitoring device is used to determine a user'"'"'s heart rate by using a heartbeat waveform sensor and a motion detecting sensor. In some embodiments, the device collects collecting concurrent output data from the heartbeat waveform sensor and output data from the motion detecting sensor, detects a periodic component of the output data from the motion detecting sensor, and uses the periodic component of the output data from the motion detecting sensor to remove a corresponding periodic component from the output data from the heartbeat waveform sensor. From this result, the device may determine and present the user'"'"'s heart rate.

Claims

1. A method of determining a user'"'"'s heart rate using a worn biometric monitoring device comprising a plurality of sensors including a heartbeat waveform sensor and a motion detecting sensor, the method comprising:

(a) collecting concurrent output data from the heartbeat waveform sensor and output data from the motion detecting sensor, wherein the output data from the heart beat waveform sensor provides information about the user'"'"'s heart rate and wherein the output data from the motion detecting sensor provides information about the user'"'"'s periodic physical movements other than heartbeats;

(b) determining a periodic component of the output data from the motion detecting sensor;

(c) filtering the output data from the heartbeat waveform sensor to remove variations that are slow with respect to an expected heart rate, wherein the filtering produces high pass filtered output data from the heartbeat waveform sensor;

(d) determining the user'"'"'s heart rate; and

(e) presenting the user'"'"'s heart rate.

2. The method of claim 1, further comprising using the periodic component of the output data from the motion detecting sensor to remove a corresponding periodic component from the high pass filtered output data from the heartbeat waveform sensor.

3. The method of claim 1, wherein the filtering removes a frequency less than about 0.6 Hz from the output data from the heartbeat waveform sensor.

4. The method of claim 1, further comprising determining the expected heart rate, and from the expected heart rate, setting a high pass frequency for the filtering.

5. The method of claim 4, wherein determining the expected heart rate comprises analyzing the output data from the motion detecting sensor.

6. The method of claim 5, wherein analyzing the output data from the motion detecting sensor comprises inferring a user activity level.

7. The method of claim 5, wherein analyzing the output data from the motion detection sensor comprises detecting an intensity of user activity or a type of user activity.

8. The method of claim 7, wherein detecting the intensity of user activity comprises detecting running or walking.

9. The method of claim 1, wherein the periodic movement detected by the motion sensor is a wearer'"'"'s limb movements.

10. The method of claim 1, wherein collecting the output data from the heartbeat waveform sensor comprises:

pulsing a light source in the worn biometric monitoring device at a first frequency; and

detecting light from the light source at the first frequency.

11. The method of claim 1, wherein presenting the user'"'"'s heart rate comprises presenting the heart rate on the worn biometric monitoring device.

12. The method of claim 1, further comprising determining the user'"'"'s resting heart rate, wherein the filtering removes a frequency less than about the frequency of the user'"'"'s resting heart rate.

13. The method of claim 12, wherein determining the user'"'"'s resting heart rate comprises measuring the user'"'"'s heart rate soon after they wake up and are while still stationary in bed.

14. The method of claim 12, wherein determining the user'"'"'s resting heart rate comprises measuring the user'"'"'s average heart rate of the user while the user is sleeping.

15. A wearable fitness monitoring device comprising:

a motion sensor configured to provide output corresponding to motion by a user wearing the fitness monitoring device;

a heartbeat waveform sensor; and

control logic comprising instructions for;

(a) collecting concurrent output data from the heartbeat waveform sensor and output data from the motion detecting sensor, wherein the output data from the heart beat waveform sensor provides information about the user'"'"'s heart rate and wherein the output data from the motion detecting sensor provides information about the user'"'"'s periodic physical movements other than heartbeats;

(b) determining a periodic component of the output data from the motion detecting sensor;

(c) filtering the output data from the heartbeat waveform sensor to remove variations that are slow with respect to an expected heart rate, wherein the filtering produces high pass filtered output data from the heartbeat waveform sensor;

(d) determining the user'"'"'s heart rate; and

(e) presenting the user'"'"'s heart rate.

16. The wearable fitness monitoring device of claim 15, wherein the heartbeat waveform sensor is a photoplethysmographic sensor comprising (i) a periodic light source, (ii) a photo detector positioned to receive periodic light emitted by the light source after interacting with the user'"'"'s skin, and (iii) circuitry determining the user'"'"'s heart rate from output of the photo detector.

17. The wearable fitness monitoring device of claim 16, wherein the photoplethysmographic sensor further comprises a housing having a recess in which the photo detector is disposed.

18. The wearable fitness monitoring device of claim 15, wherein the control logic further comprises instructions for using the periodic component of the output data from the motion detecting sensor to remove a corresponding periodic component from the high pass filtered output data from the heartbeat waveform sensor.

19. The wearable fitness monitoring device of claim 15, wherein the instructions for filtering comprise instructions for removing a frequency less than about 0.6 Hz from the output data from the heartbeat waveform sensor.

20. The wearable fitness monitoring device of claim 15, wherein the control logic further comprises instructions for determining the expected heart rate, and from the expected heart rate, setting a high pass frequency for the filtering.

21. The wearable fitness monitoring device of claim 20, wherein the instructions for determining the expected heart rate comprise instructions for analyzing the output data from the motion detecting sensor.

22. The wearable fitness monitoring device of claim 21, wherein the instructions for analyzing the output data from the motion detecting sensor comprise instructions for inferring a user activity level.

23. The wearable fitness monitoring device of claim 21, wherein the instructions for analyzing the output data from the motion detection sensor comprise instructions for detecting an intensity of user activity or a type of user activity.

24. The wearable fitness monitoring device of claim 23, wherein the instructions for detecting the intensity of user activity comprise instructions for detecting running or walking.

25. The wearable fitness monitoring device of claim 15, wherein the periodic movement detected by the motion sensor is a wearer'"'"'s limb movements.

26. The wearable fitness monitoring device of claim 15, wherein the motion detecting sensor is an accelerometer or a gyroscope.

27. The wearable fitness monitoring device of claim 15, wherein the instructions for collecting the output data from the heartbeat waveform sensor comprise instructions for:

pulsing a light source in the wearable biometric monitoring device at a first frequency; and

detecting light from the light source at the first frequency.

28. The wearable fitness monitoring device of claim 27, wherein the instructions for pulsing the light source at the first frequency comprise instructions for emitting a succession of light pulses of substantially constant intensity.

29. The wearable fitness monitoring device of claim 15, wherein the instructions for presenting the user'"'"'s heart rate comprise instructions for presenting the heart rate on the wearable biometric monitoring device.

30. The wearable fitness monitoring device of claim 15, wherein the control logic further comprises instructions for determining the user'"'"'s resting heart rate, and wherein the instructions for filtering comprise instructions for removing a frequency less than about the frequency of the user'"'"'s resting heart rate.