Determining heart rate with reflected light data
A physiological monitor switches between a time domain analysis and a frequency domain analysis for determining a heart rate based on objective indicia of signal quality in an acquired heart rate signal.
1. A wearable physiological measurement system comprising:
a wearable strap configured to be couplable to an appendage of a user, the wearable strap comprising:
one or more light emitters for emitting light toward the user;
one or more light detectors for receiving at least a portion of the light reflected from the user;
a motion sensor; and
a processing module configured to analyze data corresponding to the light reflected from the user to automatically and continually determine a heart rate of the user, wherein the processing module is configured by computer executable code stored in a memory to determine the heart rate by:
applying a peak detection algorithm to detect a plurality of peaks in the data associated with a plurality of heart beats of the user,
estimating an R-wave-to-R-wave interval (an RR interval) based on the plurality of peaks detected by the peak detection algorithm,
determining a confidence level associated with the RR interval based on the plurality of peaks detected by the peak detection algorithm, wherein the confidence level is based at least in part on a motion signal from the motion sensor, and
based on the confidence level associated with the RR interval failing to meet a predetermined threshold, changing from the peak detection algorithm to a frequency analysis algorithm to calculate the heart rate of the user based on the data.
2. The wearable physiological measurement system of claim 1 ,
wherein:
in response to determining that the confidence level associated with the RR interval is above the predetermined threshold, the processing module uses the plurality of peaks to determine the heart rate of the user; and
in response to determining that the confidence level associated with the RR interval is below the predetermined threshold, the processing module uses the frequency analysis algorithm to determine the heart rate of the user.
3. A system comprising:
a wearable physiological monitor including one or more optical detectors configured to provide an optical signal indicative of reflected light from a skin of a wearer;
a memory storing; and
one or more processors configured by computer-readable instructions stored in the memory to perform the steps of:
evaluating an accuracy of a heart rate signal derived from the optical signal when calculated using a time domain peak detection algorithm,
in response to determining that the accuracy of the heart rate signal meets a predetermined threshold, calculating a heart rate of the wearer using the time domain peak detection algorithm to evaluate the heart rate signal, and
in response to determining that the accuracy of the heart rate signal does not meet the predetermined threshold, calculating the heart rate of the wearer using a frequency domain algorithm instead of the time domain peak detection algorithm to evaluate the heart rate signal.
4. The system of claim 3 , wherein evaluating the accuracy includes using a statistical analysis to provide a confidence level in the heart rate signal.
5. The system of claim 3 , wherein the wearable physiological monitor includes a motion sensor, and wherein evaluating the accuracy includes evaluating the accuracy based at least in part on a motion signal from the motion sensor.
6. The system of claim 3 , further comprising a sensor coupled to the wearable physiological monitor, wherein evaluating the accuracy includes evaluating the accuracy based at least in part on a signal from the sensor.
7. The system of claim 6 , wherein the sensor includes one or more of a position sensor, a timer, a temperature sensor, a Galvanic Skin Response sensor, and a humidity sensor.
8. The system of claim 3 , further comprising a motion sensor, wherein the one or more processors are configured to process the heart rate signal based on a motion signal from the motion sensor to reduce contributions to the heart rate signal by a motion of the wearer.
9. The system of claim 3 , wherein the wearable physiological monitor includes a motion sensor, and wherein the frequency domain algorithm accounts for a motion of the wearer based on a motion signal from the motion sensor.
10. The system of claim 3 , wherein the wearable physiological monitor includes a wearable strap configured to couple the wearable physiological monitor to an appendage of the wearer.
11. The system of claim 3 , further comprising an accessory removably and replaceably couplable to the wearable physiological monitor, the accessory including a power source configured to charge a battery of the wearable physiological monitor without a wired coupling to other power sources.
12. The system of claim 3 , wherein the one or more processors include at least one processor in the wearable physiological monitor.
13. The system of claim 3 , wherein the one or more processors include at least one processor on a server coupled in a communicating relationship with the wearable physiological monitor.
14. The system of claim 3 , wherein the one or more processors include at least one processor on a mobile computing device associated with the wearer.
15. The system of claim 3 , wherein the one or more processors are further configured to determine a heart rate variability of the wearer based on a sequence of measurements of an instantaneous heart rate of the wearer derived from the heart rate signal.
16. A computer program product comprising non-transitory computer executable code embodied in a non-transitory computer readable medium that, when executing on one or more computing devices, performs the steps of:
receiving an optical signal from a wearable physiological monitor, the optical signal indicative of reflected light from a skin of a wearer of the wearable physiological monitor and detected by an optical detector of the wearable physiological monitor;
evaluating an accuracy of a heart rate signal derived from the optical signal when calculated using a time domain peak detection algorithm;
in response to determining that the accuracy is above a predetermined threshold, calculating a heart rate of the wearer using the time domain peak detection algorithm for heart rate detection; and
in response to determining that the accuracy is below the predetermined threshold, calculating the heart rate of the wearer using a frequency domain algorithm instead of the time domain peak detection algorithm for heart rate detection.
17. The computer program product of claim 16 , wherein evaluating the accuracy of the heart rate signal includes evaluating the accuracy based on a motion of the wearer.
18. The computer program product of claim 17 , wherein the motion is detected based on a motion signal from one or more accelerometers associated with the wearable physiological monitor.
19. The computer program product of claim 16 , wherein evaluating the accuracy includes using a statistical analysis of the heart rate signal to determine a statistical confidence level in the accuracy.
20. The computer program product of claim 16 , further comprising code that performs the step of determining a heart rate variability of the wearer based on a sequence of measurements of an instantaneous heart rate of the wearer based on the heart rate signal.