# US 10,765,332 B2 · Detection of the heartbeat in cranial accelerometer data using independent component analysis > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,765,332 B2 - Document ID: US10765332B2 - Status: Granted - Kind: B2 - Application number: 15/569,535 - Filed: 2015-04-29 - Published: 2018-10-18 - Granted: 2020-09-08 - Earliest claimed: 2015-04-29 - Assignees: Brainlab AG - Applicants: Brainlab AG - Inventors: Christian Harrer; Stephan Mittermeyer; Bálint Varkuti - Web page: https://patentgrep.com/patent/US10765332B2 ## CPC - A61B 5/02438: {with portable devices, e.g. worn by the patient} - A61B 5/02416: {using photoplethysmograph signals, e.g. generated by infrared radiation (A61B5/14552 takes precedence)} - A61B 5/0245: by using sensing means generating electric signals, {i.e. ECG signals} - A61B 5/35: by template matching - A61B 5/4064: {Evaluating the brain (for intracranial pressure A61B5/031; for cerebral blood gases A61B5/14553; using EEG A61B5/369)} - A61B 5/6803: {Head-worn items, e.g. helmets, masks, headphones or goggles} - A61B 5/6814: {Head} - A61B 5/7203: {for noise prevention, reduction or removal} - 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 5/7246: {using correlation, e.g. template matching or determination of similarity} - A61B 5/7257: {using Fourier transforms} - A61B 2562/0219: Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract The invention relates to a computer-implemented medical data processing method for determining a heartbeat signal describing the heartbeat of a patient in the time domain, the method comprising executing, on a processor of a computer, steps of: a) acquiring, at the processor, acceleration measurement data describing an acceleration in the time domain of an anatomical body part measured on an external surface of the anatomical body part; b) determining, by the processor, component analysis data describing a result of an independent component analysis in the time domain of the acceleration measurement data; c) acquiring, at the processor, heartbeat template data describing template shapes of heartbeat in the time domain; d) determining, by the processor and based on the component analysis data and the heartbeat template data, recurrent shape data describing a recurrence of certain signal shapes in the component analysis data; e) determining, based on the recurrent shape data, heartbeat signal data describing a time series of the heartbeat. ## Claims ### Claim 1 A system for determining a heartbeat signal describing the heartbeat of a patient, the system comprising: a plurality of acceleration sensors disposable on a surface of an anatomical body part of the patient and configured to generate acceleration signals for measuring an acceleration of the surface; at least one computer being operatively coupled to the acceleration sensors and configured to receive information corresponding to the acceleration signals from the acceleration sensors and to acquire acceleration measurement data based on that information, wherein the at least one computer comprises at least one processor configured to execute computer-executable instructions for a method for determining a heartbeat signal describing the heartbeat of a patient in the time domain, the instructions, when executed, configure the at least one processor to: acquire, at the at least one processor, acceleration measurement data describing an acceleration in the time domain of an anatomical body part measured on an external surface of the anatomical body part; determine, by the at least one processor, component analysis data describing a result of an independent component analysis in the time domain of the acceleration measurement data; acquire, at the at least one processor, heartbeat template data describing template shapes of heartbeat in the time domain; determine, by the at least one processor and based on the component analysis data and the heartbeat template data, recurrent shape data describing a recurrence of certain signal shapes in the component analysis data; and determine, by the at least one processor and based on the recurrent shape data, heartbeat signal data describing a time series of the heartbeat. ### Claim 2 A computer-implemented method for determining a heartbeat signal describing the heartbeat of a patient in the time domain, the method comprising: a) obtaining, from a plurality of acceleration sensors by at least one processor, acceleration measurement data describing an acceleration in the time domain of an anatomical body part measured on an external surface of the anatomical body part; b) determining, by the at least one processor, component analysis data describing a result of an independent component analysis in the time domain of the acceleration measurement data; c) acquiring, at the at least one processor, heartbeat template data describing template shapes of heartbeat in the time domain; d) determining, by the at least one processor and based on the component analysis data and the heartbeat template data, recurrent shape data describing a recurrence of certain signal shapes in the component analysis data; e) determining, by the at least one processor and based on the recurrent shape data, heartbeat signal data describing a time series of the heartbeat. ### Claim 3 (depends on 2) The method according to claim 2, wherein the anatomical body part comprises the head. ### Claim 4 (depends on 2) The method according to claim 2, comprising preprocessing, by the at least one processor, the acceleration measurement data for at least one of noise reduction, low pass filtering and high pass filtering. ### Claim 5 (depends on 2) The method according to claim 2, comprising determining, by the at least one processor, whether a real-time independent component analysis on the acceleration measurement data is possible, and if determined that the real-time independent component analysis is possible, determining, by the at least one processor, the component analysis data from a stream of the acceleration measurement data; and if determined that the real-time independent component analysis is not possible, buffering, by the at least one processor, the acceleration measurement data and determining, by the at least one processor, the component analysis data by conducting the independent component analysis on at least one batch of the buffered acceleration measurement data. ### Claim 6 (depends on 2) The method according to claim 2, comprising determining, by the at least one processor and based on the component analysis data, whether the independent component analysis of the acceleration measurement data describes recurring time domain shapes; and if determined that the independent component analysis of the acceleration measurement data describes recurring time domain shapes, determining, by the at least one processor, whether those shapes are described by the heartbeat template data; and if determined that those shapes are not described by the heartbeat template data, adding, by the at least one processor, those shapes to the heartbeat template data. ### Claim 7 (depends on 2) The method according to claim 2, comprising performing the independent component analysis by running, by the at least one processor, a fast independent component analysis algorithm on the acceleration measurement data. ### Claim 8 (depends on 2) The method according to claim 2, comprising determining, by the at least one processor and based on the heartbeat signal data, a frequency domain representation of the time series of the heartbeat; and determining, by the at least one processor and based on the frequency domain representation, whether a peak frequency described by the frequency domain representation matches a predetermined heartrate. ### Claim 9 (depends on 8) The method according to claim 8, wherein the frequency domain representation is determined by determining a Fourier transform of the time series of the heartbeat. ### Claim 10 (depends on 8) The method according to claim 8, wherein the predetermined heartrate is acquired, at the at least one processor, as second measurement data received from a second heartbeat sensor, wherein the second heartbeat sensor includes at least one of a photoplethysmography device or an electrocardiography device. ### Claim 11 (depends on 2) The method according to claim 2, wherein the heartbeat signal data is determined by executing at least one of the following: determining, by the at least one processor and based on the recurrent shape data, a single independent component; determining, by the at least one processor and based on the recurrent shape data, a combination of single independent components; or determining, by the at least one processor, at least one of a convolution cross correlation of the component analysis data and the heartbeat template data. ### Claim 12 (depends on 9) The method according to claim 9, wherein the heartbeat signal data is determined by determining, by the at least one processor, the harmonics of the frequency domain representation of the heartbeat. ### Claim 13 A non-transitory computer-readable program storage medium on which a program is stored which, when executed by at least one processor of at least one computer, causes the at least one computer to perform a method for determining a heartbeat signal describing the heartbeat of a patient in the time domain, the program for the method configures the at least one processor to: obtain, from a plurality of acceleration sensors , acceleration measurement data describing an acceleration in the time domain of an anatomical body part measured on an external surface of the anatomical body part; determine component analysis data describing a result of an independent component analysis in the time domain of the acceleration measurement data; acquire heartbeat template data describing template shapes of heartbeat in the time domain; determine, based on the component analysis data and the heartbeat template data, recurrent shape data describing a recurrence of certain signal shapes in the component analysis data; determine, based on the recurrent shape data, heartbeat signal data describing a time series of the heartbeat. ### Claim 14 (depends on 13) The non-transitory computer-readable program storage medium of claim 13, wherein the program further configures the at least one processor to preprocess the acceleration measurement data prior to the independent component analysis. ### Claim 15 (depends on 13) The non-transitory computer-readable program storage medium of claim 13, wherein, to determine recurrent shape data, the program configures the at least one processor to compare a heartbeat template shape, from the heartbeat template data, to a component channel from the component analysis data. ### Claim 16 (depends on 15) The non-transitory computer-readable program storage medium of claim 15, wherein the program further configures the at least one processor to slide the heartbeat template shape over the component channel according to a predetermined step size and identify positions where a similarity value exceeds a threshold. ### Claim 17 (depends on 15) The non-transitory computer-readable program storage medium of claim 15, wherein the program further configures the at least one processor to determine recurrence of the heartbeat template shape on the component channel within an anatomical relevant distance from the identified positions. ### Claim 18 (depends on 15) The non-transitory computer-readable program storage medium of claim 15, wherein the program further configures the at least one processor to: identify a recurring shape in at least one component channel following the independent component analysis of the acceleration measurement data; determine whether the recurring shape is described in the heartbeat template data; and add the recurring shape to the heartbeat template data when the recurring shape is not described. ### Claim 19 (depends on 15) The non-transitory computer-readable program storage medium of claim 15, wherein the program further configures the at least one processor to determine a heartrate from the heartbeat signal data. ### Claim 20 (depends on 19) The non-transitory computer-readable program storage medium of claim 19, wherein the program further configures the at least one processor to: acquire second measurement data from a second heartbeat sensor; and validate the heartrate determined from the heartbeat signal data based on the second measurement data.