Wearable heart rate monitor

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.

What is claimed is: 
     
         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 heartbeat 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) using 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;   (d) determining the user's heart rate; and   (e) presenting the user's heart rate.   
     
     
         2 . The method of  claim 1 , further comprising removing a harmonic of the corresponding periodic component from the output data from the heartbeat waveform sensor. 
     
     
         3 . The method of  claim 2 , wherein the periodic component of the output data from the motion detecting sensor is a fundamental frequency produced from the user's periodic movement. 
     
     
         4 . The method of  claim 1 , wherein removing a corresponding periodic component from the output data from the heartbeat waveform sensor comprises applying an adaptive filter to the output data from the heartbeat waveform sensor and the output data from the motion detecting sensor. 
     
     
         5 . The method of  claim 1 , wherein removing a corresponding periodic component from the output data from the heartbeat waveform sensor comprises applying an adaptive filter function to the output data from the motion detecting sensor that minimizes the difference between the output data from the heartbeat waveform sensor and the output data from the motion detecting sensor. 
     
     
         6 . The method of  claim 1 , further comprising:
 determining the user's activity level and/or activity type; and   determining parameters of the function based on the user's activity level and/or activity type.   
     
     
         7 . The method of  claim 1 , further comprising:
 analyzing the output data from the motion detecting sensor to infer that the user is substantially stationary; and   temporarily suspending operation (c).   
     
     
         8 . The method of  claim 1 , wherein the periodic movement detected by the motion sensor is a wearer's limb movements. 
     
     
         9 . The method of  claim 8 , wherein the limb movements are steps, swim strokes, ankle revolutions while bicycling, and leg movements on cardio machines. 
     
     
         10 . The method of  claim 1 , wherein the motion detecting sensor is an accelerometer or a gyroscope. 
     
     
         11 . The method of  claim 1 , wherein the heartbeat waveform sensor comprises a photoplethysmography sensor or an ECG sensor. 
     
     
         12 . 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.   
     
     
         13 . The method of  claim 12 , wherein pulsing the light source at the first frequency comprises emitting a succession of light pulses of substantially constant intensity. 
     
     
         14 . The method of  claim 1 , wherein presenting the user's heart rate comprises presenting the heart rate on the worn biometric monitoring device. 
     
     
         15 . The method of  claim 1 , wherein presenting the user's heart rate comprises presenting the heart rate on an external device that periodically communicates with the worn biometric monitoring device. 
     
     
         16 . 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.   
     
     
         17 . The method of  claim 16 , 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. 
     
     
         18 . The method of  claim 16 , wherein the filtering removes a frequency less than about 0.6 Hz from the output data from the heartbeat waveform sensor. 
     
     
         19 . The method of  claim 16 , further comprising determining the expected heart rate, and from the expected heart rate, setting a high pass frequency for the filtering. 
     
     
         20 . The method of  claim 19 , wherein determining the expected heart rate comprises analyzing the output data from the motion detecting sensor. 
     
     
         21 . The method of  claim 20 , wherein analyzing the output data from the motion detecting sensor comprises inferring a user activity level. 
     
     
         22 . The method of  claim 20 , wherein analyzing the output data from the motion detection sensor comprises detecting an intensity of user activity or a type of user activity. 
     
     
         23 . The method of  claim 22 , wherein detecting the intensity of user activity comprises detecting running or walking. 
     
     
         24 . The method of  claim 16 , wherein the periodic movement detected by the motion sensor is a wearer's limb movements. 
     
     
         25 . The method of  claim 16 , 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.   
     
     
         26 . The method of  claim 16 , wherein presenting the user's heart rate comprises presenting the heart rate on the worn biometric monitoring device. 
     
     
         27 . The method of  claim 16 , 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. 
     
     
         28 . The method of  claim 27 , 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. 
     
     
         29 . The method of  claim 27 , wherein determining the user's resting heart rate comprises measuring the user's average heart rate of the user while the user is sleeping.