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Heart rate estimation apparatus with state sequence optimization

  • US 10,321,831 B2
  • Filed: 08/16/2016
  • Issued: 06/18/2019
  • Est. Priority Date: 11/25/2015
  • Status: Active Grant
First Claim
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1. A heart rate monitor system to estimate a heart rate of a patient, the heart rate monitor system comprising:

  • a light source configured to direct a first light signal toward a patient;

    an optical sensor configured to;

    detect a second light signal from the patient, the second light signal representing transmission or reflection of the first light signal in the patient; and

    generate an analog photoplethysmogram (PPG) signal representing the second light signal;

    an analog to digital converter configured to generate a plurality of digital PPG sample values of the PPG signal in a time window; and

    a processor circuit configured to;

    for the time window;

    obtain a frequency domain spectrum according to the digital PPG sample values; and

    identify a plurality of heart rate hypothesis states having amplitudes in the frequency domain spectrum greater than a threshold value;

    identify a plurality of potential heart rate transition pairs, each representing a respective heart rate transition between;

    a corresponding one of the heart rate hypothesis states for the time window; and

    one of a plurality of heart rate hypothesis states for a previous time window;

    for each potential heart rate transition pair, compute;

    a respective heart rate change value; and

    a respective branch metric value as a function of the respective heart rate change value and a frequency domain amplitude of the potential heart rate transition pair'"'"'s corresponding one of the heart rate hypothesis states for the time window;

    for each heart rate hypothesis state for the time window;

    compute a plurality of candidate path metric values, each as a sum of a corresponding branch metric value and a path metric value for a corresponding one of the heart rate hypothesis states for the previous time window; and

    select a largest one of the candidate path metric values to be the heart rate hypothesis state'"'"'s respective path metric value; and

    determine a heart rate estimate value, representing the heart rate of the patient for the time window, as the heart rate hypothesis state whose respective path metric value is largest.

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