On-demand heart rate estimation based on optical measurements
First Claim
1. A system for determining a heart rate from a heartbeat signal present in a first signal generated by a heartbeat sensor, the system comprising:
- means for computing an autocorrelation of data samples of the first signal over a first time period;
means for processing a second signal to evaluate motion of the heartbeat sensor during the first time period, the second signal indicative of a motion of the heartbeat sensor with respect to one or more directions;
means for determining whether the data samples of the first signal over the first time period pass a set of confidence checks, the set of confidence checks comprising at leastdetermining whether the motion of the heartbeat sensor during the first time period satisfies a motion-related criteria;
means for computing a first estimate of the heart rate from the autocorrelation of the data samples of the first signal over the first time period upon determination that the data samples of the first signal over the first time period pass the set of confidence checks;
means for computing a Discrete Fourier Transform (DFT) for data samples of the first signal over a second time period;
means for computing a second estimate of the heart rate from the DFT; and
means for determining the heart rate based on a comparison of the first estimate and the second estimate.
1 Assignment
0 Petitions
Accused Products
Abstract
Activity monitors and smart watches utilizing optical measurements are becoming widely popular, and users expect to get an increasingly accurate estimate of their heart rate (HR) from these devices. These devices are equipped with a light source and an optical sensor which enable estimation of HR using a technique called photoplethysmography (PPG). One of the main challenges of HR estimation using PPG is the coupling of motion into the optical PPG signal when the user is moving randomly or exercising. The present disclosure describes a computationally feasible and fast HR estimation algorithm to be executed at instances of little or no motion. Resulting HR readings may be useful on their own, or be provided to systems that monitor HR continuously to prevent the problem of such systems being locked on an incorrect HR for long periods of time. Implementing techniques described herein leads to more accurate HR measurements.
3 Citations
20 Claims
-
1. A system for determining a heart rate from a heartbeat signal present in a first signal generated by a heartbeat sensor, the system comprising:
-
means for computing an autocorrelation of data samples of the first signal over a first time period; means for processing a second signal to evaluate motion of the heartbeat sensor during the first time period, the second signal indicative of a motion of the heartbeat sensor with respect to one or more directions; means for determining whether the data samples of the first signal over the first time period pass a set of confidence checks, the set of confidence checks comprising at least determining whether the motion of the heartbeat sensor during the first time period satisfies a motion-related criteria; means for computing a first estimate of the heart rate from the autocorrelation of the data samples of the first signal over the first time period upon determination that the data samples of the first signal over the first time period pass the set of confidence checks; means for computing a Discrete Fourier Transform (DFT) for data samples of the first signal over a second time period; means for computing a second estimate of the heart rate from the DFT; and means for determining the heart rate based on a comparison of the first estimate and the second estimate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. A system for determining a heart rate from a heartbeat signal present in a signal generated by a heartbeat sensor, the system comprising:
-
means for computing an autocorrelation of data samples of the signal over a first time period; means for determining whether the data samples of the signal over the first time period satisfy a motion-related criteria; means for computing, when the data samples of the signal over the first time period satisfy the motion-related criteria, a first estimate of the heart rate based on the autocorrelation; means for computing a Fourier Transform (FT) for data samples of the signal over a second time period; means for computing a second estimate of the heart rate based on the FT; and means for determining the heart rate based on a comparison of the first estimate and the second estimate. - View Dependent Claims (18)
-
-
19. A system for determining a heart rate from a heartbeat signal present in a first signal generated by a heartbeat sensor, the system comprising:
-
means for computing an autocorrelation of data samples of the signal over a first time period; means for determining whether the data samples of the signal over the first time period satisfy a motion-related criteria; means for computing, when the data samples of the signal over the first time period satisfy the motion-related criteria, a first estimate of the heart rate based on the autocorrelation; means for computing a Fourier Transform (FT) for data samples of the signal over a second time period, wherein the second time period includes the first time period; means for computing a second estimate of the heart rate based on the FT; and means for determining the heart rate based the first estimate and the second estimate. - View Dependent Claims (20)
-
Specification