# US 10,478,129 B2 · Methods for improving response time, robustness and user comfort in continuous estimation of biophysiological rates > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,478,129 B2 - Document ID: US10478129B2 - Status: Granted - Kind: B2 - Application number: 14/931,440 - Filed: 2015-11-03 - Published: 2016-08-04 - Granted: 2019-11-19 - Earliest claimed: 2015-01-30 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Samsung Electronics Co., LTD - Inventors: Matthew C. Wiggins; Asif Khalak; Yelei Li - Web page: https://patentgrep.com/patent/US10478129B2 ## CPC - A61B 5/7264: {Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems} - A61B 5/02416: {using photoplethysmograph signals, e.g. generated by infrared radiation (A61B5/14552 takes precedence)} - A61B 5/0816: {Measuring devices for examining respiratory frequency (measuring frequency of electric signals G01R23/00)} - A61B 5/1455: using optical sensors, e.g. spectral photometrical oximeters - A61B 5/7203: {for noise prevention, reduction or removal} - A61B 5/7207: {of noise induced by motion artifacts} - A61B 5/7221: {Determining signal validity, reliability or quality (preventing, reducing or removing noise induced by motion artefacts A61B5/7207; noise originating from a therapeutic or surgical apparatus A61B5/7217)} - A61B 5/7225: {Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316)} - A61B 5/7253: {characterised by using transforms} - A61B 5/7278: {Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals} - G01N 33/4833: {of solid biological material, e.g. tissue samples, cell cultures (tissue in vivo A61B5/00; cell suspensions G01N33/48735)} - G16H 50/20: for computer-aided diagnosis, e.g. based on medical expert systems - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA ## Abstract A computer-implemented method for estimating biophysiological rates using the Hilbert transform includes receiving a quasiperiodic data stream from a biophysiological sensor, and removing at least a portion of an offset from the quasiperiodic data stream to provide a smoothed data stream by filtering the quasiperiodic data stream through a bandpass filter and phase compensating the filtered quasiperiodic data stream. The method also includes transforming the smoothed data stream into an analytic data stream using a Hilbert transform approximation and calculating the time derivative of the phase angle of the analytic data stream, where the time derivative is a frequency of the quasiperiodic data stream. The method further includes providing an output data stream derived from the frequency. ## Claims ### Claim 1 An apparatus for determining a biophysiological feature, the apparatus comprising: a memory having machine instructions stored therein; a processor coupled to the memory; a biophysiological sensor coupled to the processor, the biophysiological sensor configured for application to a patient and operable for detecting signals in the patient associated with measuring a quasiperiodic function; and an input/output device; wherein the processor executes the machine instructions to: receive a quasiperiodic data stream for the measured quasiperiodic function from the biophysiological sensor, remove at least a portion of an offset from the quasiperiodic data stream to provide a smoothed data stream by filtering the quasiperiodic data stream through a bandpass filter and phase compensating the filtered quasiperiodic data stream, transform the smoothed data stream into an analytic data stream using a Hilbert transform approximation, calculate a time derivative associated with a phase angle of the analytic data stream, provide, to a user via the input/output device, an output data stream derived from a frequency, wherein the frequency is the time derivative of the quasiperiodic data stream and wherein the output data stream comprises the biophysiological feature, and mask the output data stream while a sensor motion fault is detected. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the processor further executes the machine instructions to: determine a magnitude of the analytic data stream, the magnitude comprising an envelope of the quasiperiodic data stream, and detect a transient irregularity of the analytic data stream based on the envelope. ### Claim 3 (depends on 2) The apparatus of claim 2, wherein the processor further executes the machine instructions to detect the transient irregularity of the analytic data stream based on: smoothing the envelope through a first filter with a first cutoff frequency, the output of the first filter comprising a first smoothed envelope, smoothing the envelope through a second filter with a second cutoff frequency that is lower than the first cutoff frequency, the output of the second filter comprising a second smoothed envelope, comparing a first logarithmic ratio of the envelope and the first smoothed envelope with a second logarithmic ratio of the envelope and the second smoothed envelope, and masking the output data stream while the comparison exceeds a predetermined limit. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the quasiperiodic data stream is an electrocardiogram (ECG) electrode signal. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the quasiperiodic data stream is a photoplethysmogram (PPG) sensor signal. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the quasiperiodic function is a sensed heartbeat and the biophysiological feature is a heartbeat rate. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the quasiperiodic function is a sensed heartbeat and the biophysiological feature is a heart interbeat interval. ### Claim 8 A method for determining a biophysiological feature, the method comprising: measuring a quasiperiodic function with a biophysiological sensor that is configured for application to a patient and operable for detecting signals in the patient associated with the quasiperiodic function; receiving, at a sensor signal receiver, a quasiperiodic data stream for the measured quasiperiodic function from the biophysiological sensor; removing, with a processor comprising a signal offset remover coupled to the sensor signal receiver and comprising a bandpass filter, at least a portion of an offset from the quasiperiodic data stream to provide a smoothed data stream by filtering the quasiperiodic data stream through the bandpass filter and phase compensating the filtered quasiperiodic data stream; with a rate estimator of the processor coupled to the signal offset remover: transforming the smoothed data stream into an analytic data stream using a Hilbert transform approximation; calculating a time derivative associated with a phase angle of the analytic data stream; and providing, to a user via an input/output device, an output data stream derived from a frequency, wherein the frequency is the time derivative of the quasiperiodic data stream and wherein the output data stream comprises the biophysiological feature; and masking, with an excursion fault detector coupled to the rate estimator, the output data stream while a sensor motion fault is detected. ### Claim 9 (depends on 8) The method of claim 8, further comprising and with the rate estimator: determining a magnitude of the analytic data stream, wherein the magnitude is an envelope of the quasiperiodic data stream; and detecting a transient irregularity of the analytic data stream based on the envelope. ### Claim 10 (depends on 9) The method of claim 9, wherein said detecting the transient irregularity of the analytic data stream based on the envelope comprises: smoothing the envelope through a first filter with a first cutoff frequency, wherein the output of the first filter is a first smoothed envelope; smoothing the envelope through a second filter with a second cutoff frequency that is lower than the first cutoff frequency, wherein the output of the second filter is a second smoothed envelope; comparing a first logarithmic ratio of the envelope and the first smoothed envelope with a second logarithmic ratio of the envelope and the second smoothed envelope; and masking the output data stream while the comparison exceeds a predetermined limit. ### Claim 11 (depends on 8) The method of claim 8, wherein the quasiperiodic data stream is an electrocardiogram (ECG) electrode signal. ### Claim 12 (depends on 8) The method of claim 8, wherein the quasiperiodic data stream is a photoplethysmogram (PPG) sensor signal. ### Claim 13 (depends on 8) The method of claim 8, wherein the quasiperiodic function is a sensed heartbeat and the output data stream is selected from the group consisting of: a heartbeat rate; and a heart interbeat interval. ### Claim 14 An apparatus for signal processing, the apparatus comprising: a memory having machine instructions stored therein; a processor coupled to the memory; and a biophysiological sensor coupled to the processor and operable for sensing a heartbeat of a patient; wherein the processor executes the machine instructions to: receive a signal comprising a quasiperiodic data stream for the sensed heartbeat from the biophysiological sensor, remove at least a portion of an offset from the signal to center the signal at a target voltage and provide a smoothed data stream by filtering the signal through a bandpass filter and phase compensating the filtered quasiperiodic data stream, transform the smoothed data stream into an analytic data stream using a Hilbert transform approximation, calculate a time derivative associated with a phase angle of the analytic data stream, provide, to a user via an input/output device, an output data stream derived from a frequency, wherein the frequency is the time derivative of the quasiperiodic data stream and wherein the output data stream comprises at least one of a heartbeat rate and a heart interbeat interval, and mask the output data stream during a sensor motion fault. ### Claim 15 (depends on 14) The apparatus of claim 14, wherein the processor further executes the machine instructions to: determine a magnitude of the analytic data stream, the magnitude comprising an envelope of the quasiperiodic data stream, and detect a transient irregularity of the analytic data stream based on the envelope. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the processor further executes the machine instructions to detect the transient irregularity of the analytic data stream based on: smoothing the envelope through a first filter with a first cutoff frequency, the output of the first filter comprising a first smoothed envelope, smoothing the envelope through a second filter with a second cutoff frequency that is lower than the first cutoff frequency, the output of the second filter comprising a second smoothed envelope, comparing a first logarithmic ratio of the envelope and the first smoothed envelope with a second logarithmic ratio of the envelope and the second smoothed envelope, and masking the output data stream while the comparison exceeds a predetermined limit. ### Claim 17 (depends on 14) The apparatus of claim 14, wherein the quasiperiodic data stream is an electrocardiogram (ECG) electrode signal. ### Claim 18 (depends on 14) The apparatus of claim 14, wherein the quasiperiodic data stream is a photoplethysmogram (PPG) sensor signal. ### Claim 19 (depends on 14) The apparatus of claim 14, wherein the biophysiological sensor is configured for application to the patient and is operable for detecting signals in the patient associated with the heartbeat.