WO2022223957A1

WO2022223957A1 - Method and system for correcting heartrate values derived from a heart rate signal

Info

Publication number: WO2022223957A1
Application number: PCT/GB2022/050971
Authority: WO
Inventors: David ROBERTAUD
Original assignee: Prevayl Innovations Limited
Priority date: 2021-04-21
Filing date: 2022-04-19
Publication date: 2022-10-27
Also published as: GB2606140A; GB202105692D0

Abstract

The method is performed by a computing apparatus comprising a processor, a memory and a communicator. The processor obtains, from the memory, a first valid pair of values comprising a heartrate value and a timestamp (S401). The processor receives, from the communicator, a pair of values comprising a heartrate value and a timestamp occurring after the timestamp obtained from memory (S402). The processor determines whether the received pair of values satisfy a validity criterion (S403). If so, the received pair of values are set as a second valid pair of values and used with the first valid pair of values to create an intermediate pair of values (S404). The intermediate pair of values comprises a heartrate value and an intermediate timestamp between the timestamps for the valid pairs of values. The original heartrate value associated with the intermediate timestamp is replaced with a corrected heartrate value that better reflects the heartrate signal.

Description

METHOD AND SYSTEM FOR CORRECTING HEARTRATE VALUES DERIVED FROM A HEART

RATE SIGNAL

The present invention is directed towards a method and system for identifying and/or correcting erroneous heartrate values derived from a heartrate signal.

Background

Wearable articles, such as garments, incorporating sensors are wearable electronics used to measure and collect information from a wearer. Such wearable articles are commonly referred to as ‘smart clothing’. It is advantageous to measure biosignals of the wearer during exercise, or other scenarios.

It is known to provide a garment, or other wearable article, to which an electronic device (i.e. an electronics module, and/or related components) is attached in a prominent position, such as on the chest or between the shoulder blades. Advantageously, the electronic device is a detachable device. The electronic device is configured to process the incoming signals, and the output from the processing is stored and/or displayed to a user in a suitable way

A sensor senses a biosignal such as electrocardiogram (ECG) signals and the biosignals are coupled to the electronic device, via an interface. The sensors may be coupled to the interface by means of conductors which are connected to terminals provided on the interface to enable coupling of the signals from the sensor to the interface.

Electronics modules for wearable articles such as garments are known to communicate with user electronic devices over wireless communication protocols such as Bluetooth ® and Bluetooth ® Low Energy. These electronics modules are typically removably attached to the wearable article, interface with internal electronics of the wearable article, and comprise a Bluetooth ® antenna for communicating with the user electronic device.

The electronic device includes drive and sensing electronics comprising components and associated circuitry, to provide the required functionality. The drive and sensing electronics include a power source to power the electronic device and the associated components of the drive and sensing circuitry.

ECG sensing is used to provide a plethora of information about a person’s heart. It is one of the simplest and oldest techniques used to perform cardiac investigations. In its most basic form, it provides an insight into the electrical activity generated within heart muscles that changes over time. By detecting and amplifying these differential biopotential signals, a lot of information can be gathered quickly, including the heartrate. Among professional medical staff, individual signals have names such as “the QRS complex,” which is the largest part of an ECG signal and is a collection of Q, R, and S signals, including the P and T waves.

Typically, the detected ECG signals can be displayed as a trace to a user for information. The user may be a clinician who is looking to assess cardiac health or may be a lay user using the electronics module as a fitness or health and wellness assessment device. Atypical ECG waveform or trace is illustrated in Figure 1 showing the QRS complex. Figure 2 shows an ECG waveform of two successive heartbeats. The time difference between the two R peaks in the ECG waveform is the inter-beat interval (IBI) also known as the R-R interval. This time is usually expressed in milliseconds. IBI values represent the time between successive heartbeats.

During exercise, a user’s heart rate will vary. Generally, the higher the heartrate, the more intense the workout. As such a measure of a user’s heartrate, whilst working out, provides an indication of the intensity of the workout.

It can be challenging to obtain a consistently accurate measure of the heartrate of the user particularly in a non-clinical setting. In the field of consumer wearable electronics, it is desirable to provide sensing electrodes that are not required to be adhered to the user using a conductive gel while worn. So called ‘dry’ electrodes are generally more comfortable to wear and are reusable making them suitable to be incorporated in wearable articles such as garments. However, it can be challenging to maintain a consistently accurate heartrate signal using dry electrodes especially when the user is moving during vigorous exercise.

It is an object of the present disclosure to provide method and system for identifying and/or correcting erroneous heartrate values derived from a heartrate signal.

Summary

According to the present disclosure there is provided a method and system as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

According to a first aspect of the disclosure, there is provided a method performed by a computing apparatus for correcting heartrate values derived from a heartrate signal. The computing apparatus comprises a processor, a memory and a communicator.

The method comprises obtaining, by the processor from the memory, a first valid pair of values comprising a heartrate value for the heartrate signal and a timestamp representative of the time window that the heartrate value relates to.

The method comprises receiving, by the processor from the communicator, a pair of values comprising a heartrate value forthe heartrate signal and a timestamp representative of the time window that the heartrate value relates to, the timestamp occurring after the timestamp for the first valid pair of values.

The method comprises determining, by the processor, whether the received pair of values satisfy a validity criterion.

If the received pair of values satisfy the validity criterion, the method further comprises: setting, by the processor, the received pair of values as a second valid pair of values; and using, by the processor, the first and second valid pair of values to create at least one intermediate pair of values. Each of the intermediate pairs of values comprises a heartrate value and an intermediate timestamp representative of the time window that the heartrate value belongs to.

Each of the intermediate timestamps occurs between the timestamp for the first valid pair of values and the timestamp for the second valid pair of values.

Advantageously, the present disclosure determines whether a received pair of values are valid and if so, uses the valid pairs of values to create corrected heartrate values. In this way, valid pairs of values received from an electronics module of a wearable article are used to correct invalid/erroneous pairs of values received from the electronics module.

Advantageously still, by performing the method on the computing apparatus rather than the electronics module, additional operations are not required to be performed by the electronics module. The electronics module is generally desired to be a low-power device with a small-form factor which is intended to be worn discretely and operate for several hours or days without requiring recharging. Performing the method on the computing apparatus (e.g. a user electronic device such as a phone) reduces the number of computational processes performed by the electronics module.

Using the first and second pair of values to create the at least one intermediate pair of values may comprise: obtaining, by the processor from the memory, at least one intermediate timestamp that occurs between the timestamps for the first and second valid pairs of values; and setting, by the processor, a heartrate value for each of the at least one intermediate timestamp using the first and second pair of values so as to form the at least one intermediate pair of values.

This may mean that intermediate timestamps associated with heartrate values previously determined to be erroneous are obtained from memory and set with new, corrected heartrate values.

Using the first and second valid pair of values to create at least one intermediate pair of values may comprise using the first and second valid pair of values to determine the coefficients of a polynomial function in which time is the independent variable and heartrate is the dependent variable.

The polynomial function may be a linear function. Advantageously, a linear function is computationally efficient and can avoid issues associated with overfitting data to a function.

Using the first and second valid pair of values to create at least one intermediate pair of values may further comprise: obtaining, from the memory, at least one intermediate timestamp that occurs between the timestamps for the first and second valid pairs of values; and inputting the at least one intermediate timestamp into the polynomial function to obtain a corresponding heartrate value for each of the at least one intermediate timestamps.

If the received pair of values does not satisfy the validity criterion, the method may further comprise storing, in the memory of the computing apparatus, the timestamp forthe received pair of values as an intermediate timestamp. In this way, if the received pair of values are determined to be invalid/erroneous, the intermediate timestamp is stored so that it may be used to generate a corrected heartrate value subsequently. The heartrate value forthe received pair of values may be discarded to reduce computational costs associated with storing and accessing values.

Determining whether the received pair of values satisfy a validity criterion may comprise determining whether the rate of change in heartrate from the heartrate value for the first valid pair of values to the heartrate value for the received pair of values exceeds a threshold value.

Determining whether the received pair of values satisfy a validity criterion may comprise determining the difference between the heartrate value for the received pair of values and the heartrate value for the first valid pair of values.

Determining whether the received pair of values satisfy a validity criterion may comprise determining the difference between the timestamp for the received pair of values and the timestamp for the first valid pair of values.

Determining whether the received pair of values satisfy a validity criterion may comprise dividing the difference between the heartrate value for the received pair of values and the heartrate value for the first valid pair of values by the difference between the timestamp for the received pair of values and the timestamp for the first valid pair of values.

Determining whether the received pair of values satisfy a validity criterion may comprise comparing the result of dividing the difference between the heartrate value forthe received pair of values and the heartrate value forthe first valid pairof values by the difference between the timestamp forthe received pairof values and the timestamp for the first valid pair of values to a threshold value.

Determining whether the received pair of values satisfy a validity criterion may comprises comparing the heartrate value for the received pair of values to a maximum threshold value.

Determining whether the received pair of values satisfy a validity criterion may comprise comparing the heartrate value for the received pair of values to a minimum threshold value.

The method may further comprise displaying, on a display of the computing apparatus, the first valid pair of values, the at least one intermediate pair of values, and the second valid pair of values.

According to a second aspect of the disclosure, there is provided a method performed by a system for correcting heartrate values derived from a heartrate signal.

The system comprising an electronics module for a wearable article. The electronics module comprising a processor, a memory, a communicator and a sensing component.

The system comprising a computing apparatus comprising a processor, a memory and a communicator. The method comprises obtaining, by the processor of the computing apparatus from the memory of the computing apparatus, a first valid pair of values comprising a heartrate value for the heartrate signal and a timestamp representative of the time window that the heartrate value relates to.

The method comprises receiving, by the processor of the electronics module from the sensing component, a heartrate signal representative of the heartrate of a wearer of the wearable article.

The method comprises determining, by the processor of the electronics module from the heartrate signal, a heartrate value for the heartrate signal.

The method comprises controlling, by the processor of the electronics module, the communicator of the electronics module to transmit a pair of values comprising the heartrate value and a timestamp representative of the time window that the heartrate value relates to, the timestamp occurring after the timestamp for the first valid pair of values.

The method comprises receiving, by the communicator of the computing apparatus, the pair of values from the electronics module.

The method comprises determining, by the processor of the computing apparatus, whether the received pair of values satisfy a validity criterion.

If the received pair of values satisfy the validity criterion, the method further comprises: setting, by the processor of the computing apparatus, the received pair of values as a second valid pair of values; and using, by the processor of the computing apparatus, the first and second valid pair of values to create at least one intermediate pair of values.

Each of the intermediate pairs of values comprises a heartrate value and an intermediate timestamp representative of the time window that the heartrate value belongs to.

According to a third aspect of the disclosure, there is provided a computing apparatus comprising a processor, a memory and a communicator, the memory storing instructions which, when executed by the processor, cause the processor to perform operations.

The operations comprise obtaining, from the memory, a first valid pair of values comprising a heartrate value derived from a heartrate signal and a timestamp representative of the time window that the heartrate value relates to.

The operations comprise receiving, from the communicator, a pair of values comprising a heartrate value derived from the heartrate signal and a timestamp representative of the time window that the heartrate value relates to, the timestamp occurring after the timestamp for the first valid pair of values. The operations comprise determining whether the received pair of values satisfy a validity criterion.

If the received pair of values satisfy the validity criterion, the operations further comprise: setting the received pair of values as a second valid pair of values; and using the first and second valid pair of values to create at least one intermediate pair of values.

Each of the intermediate pairs of values comprises a heartrate value and a timestamp representative of the time window that the heartrate value belongs to.

According to a fourth aspect of the disclosure, there is provided a system.

The system comprising: an electronics module for a wearable article, the electronics module comprising a processor, a memory, a communicator and a sensing component.

The system comprising a computing apparatus comprising a processor, a memory and a communicator.

The processor of the computing apparatus is operable to obtain, from the memory of the computing apparatus, a first valid pair of values comprising a heartrate value representative of a heartrate signal and a timestamp representative of the time window that the first heartrate value relates to.

The processor of the electronics module is operable to receive, from the sensing component, a heartrate signal representative of the heartrate of a wearer of the wearable article.

The processor of the electronics module is operable to determine, from the heartrate signal, a heartrate value for the heartrate signal.

The processor of the electronics module is operable to control the communicatorto transmit a pair of values comprising the heartrate value and a timestamp representative of the time window that the heartrate value relates to, the timestamp occurring after the timestamp for the first valid pair of values.

The communicator of the computing apparatus is operable to receive the pair of values from the electronics module.

The processor of the computing apparatus is operable to determine whether the received pair of values satisfy a validity criterion.

If the received pair of values satisfy the validity criterion, the processor of the computing apparatus is operable to set the received pair of values as a second valid pair of values and use the first and second valid pair of values to create at least one intermediate pair of values. Each of the intermediate pairs of values comprises a heartrate value and a timestamp representative of the time window that the heartrate value belongs to.

According to a fifth aspect of the disclosure, there is provided a method performed by a computing apparatus for identifying invalid heartrate values derived from a heartrate signal.

The computing apparatus comprising a processor, a memory and a communicator.

The method comprises determining, by the processor, whether the rate of change in heartrate from the heartrate value forthe first valid pair of values to the heartrate value forthe received pair of values exceeds a threshold.

If the rate of change in heartrate exceeds the threshold, the method comprises identifying the received heartrate value as invalid.

A computing apparatus and system implementing the method according to the fifth aspect are also provided.

The method of the fifth aspect may comprise any or all of the features of the method of the first aspect.

According to a sixth aspect of the disclosure, there is provided a method performed by a computing apparatus for correcting heartrate values derived from a heartrate signal, the computing apparatus comprising a processor and a memory.

The method comprises obtaining, by the processor from the memory, a second valid pair of values comprising a heartrate value for the heartrate signal and a timestamp representative of the time window that the heartrate value relates to. The method comprises using, by the processor the first and second valid pair of values to determine the coefficients of a polynomial function in which time is the independent variable and heartrate is the dependent variable.

The method comprises inputting an intermediate timestamp occurring between the timestamp for the first valid pair of values and the timestamp forthe second valid pair of values into the polynomial so as to obtain, as an output of the polynomial function, a heartrate value corresponding to the intermediate timestamp.

The intermediate timestamp and heartrate value form an intermediate pair of values.

A computing apparatus and system implementing the method according to the sixth aspect are also provided.

The method of the sixth aspect may comprise any or all of the features of the method of the first aspect.

In the above examples of the present disclosure, the computing apparatus may be a user electronic device.

In the above examples of the present disclosure, the heartrate signal may be an electrocardiogram, ECG, signal but this is not required in all examples and other signals indicative of the heartrate are within the scope of the present disclosure. Other signals indicative of the heartrate include photoplethysmography (PPG) signals, ballistocardiogram (BCG) signals, and electromagnetic cardiogram (EMCG) signals.

In the above examples, the peaks may be R-peaks in an ECG or similar signal. The IBI values may be R- R interval values. The peaks are not required to be R-peaks. The method may be for detecting other characteristic peaks of an ECG or similar signal such as S-peaks or other characteristic peaks in signals indicative of the heartrate of the subject.

Brief Description of the Drawings

Examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

Figure 1 illustrates a signal trace for an ECG signal;

Figure 2 illustrates an ECG waveform that includes electrical signals for two successive heartbeats;

Figure 3 shows a schematic diagram for an example system according to aspects of the present disclosure;

Figure 4 shows a schematic diagram for an example electronics module according to aspects of the present disclosure;

Figure 5 shows a schematic diagram for another example electronics module according to aspects of the present disclosure; Figure 6 shows a schematic diagram for an example analogue-to-digital converter used in the example electronics module of Figures 4 and 5 according to aspects of the present disclosure;

Figure 7 shows a schematic diagram of the components of an example user electronics device according to aspects of the present disclosure;

Figures 8 shows a flow diagram for an example method of detecting peaks in a heartrate signal according to aspects of the present disclosure;

Figure 9 is a plot of example pairs of values received by a user electronics device from an electronics module;

Figure 10 is a plot showing the pairs of values in Figure 9 with some of the heartrate values corrected according to aspects of the present disclosure;

Figure 11 shows a flow diagram for an example method of identifying erroneous pairs of values according to aspects of the present disclosure;

Figure 12 shows a flow diagram for an example method of correcting erroneous pairs of values according to aspects of the present disclosure;

Figure 13 is a plot of example of example pairs of values received by a user electronics device from an electronics module;

Figure 14 is a plot showing the pairs of values in Figure 13 with some of the heartrate values corrected according to aspects of the present disclosure;

Figure 15 shows a flow diagram for an example method of correcting erroneous pairs of values according to aspects of the present disclosure;

Figure 16 is a swim-lane diagram showing an example method of correcting erroneous pairs of values according to aspects of the present disclosure; and

Figure 17 shows a screenshot of a training application running on a user electronics device according to aspects of the present disclosure;

Detailed Description

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings but are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

“Wearable article” as referred to throughout the present disclosure may refer to any form of article which may be worn by a user such as a smart watch, necklace, garment, bracelet, or glasses. The wearable article may be a textile article. The wearable article may be a garment. The garment may refer to an item of clothing or apparel. The garment may be a top. The top may be a shirt, t-shirt, blouse, sweater, jacket/coat, or vest. The garment may be a dress, garment brassiere, shorts, pants, arm or leg sleeve, vest, jacket/coat, glove, armband, underwear, headband, hat/cap, collar, wristband, stocking, sock, or shoe, athletic clothing, personal protective equipment, including hard hats, swimwear, wetsuit or dry suit.

The term “wearer” includes a user who is wearing, or otherwise holding, the wearable article.

The type of wearable garment may dictate the type of biosignals to be detected. For example, a hat or cap may be used to detect electroencephalogram or magnetoencephalogram signals.

The wearable article/garment may be constructed from a woven or a non-woven material. The wearable article/garment may be constructed from natural fibres, synthetic fibres, or a natural fibre blended with one or more other materials which can be natural or synthetic. The yarn may be cotton. The cotton may be blended with polyester and/or viscose and/or polyamide according to the application. Silk may also be used as the natural fibre. Cellulose, wool, hemp and jute are also natural fibres that may be used in the wearable article/garment. Polyester, polycotton, nylon and viscose are synthetic fibres that may be used in the wearable article/garment.

The garment may be a tight-fitting garment. Beneficially, a tight-fitting garment helps ensure that the sensor devices of the garment are held in contact with or in the proximity of a skin surface of the wearer. The garment may be a compression garment. The garment may be an athletic garment such as an elastomeric athletic garment.

The garment has sensing units provided on an inside surface which are held in close proximity to a skin surface of a wearer wearing the garment. This enables the sensing units to measure biosignals for the wearer wearing the garment.

The sensing units may be arranged to measure one or more biosignals of a wearer wearing the garment. “Biosignal” as referred to throughout the present disclosure may refer to signals from living beings that can be confinuaiiy measured or monitored. Biosignals may be electrical or non-electrical signals. Signal variations can be time variant or spatially variant.

Sensing components may be used for measuring one or a combination of bioelectrical, bioimpedance, biochemical, biomechanical, bioacoustics, biooptical or biothermal signals of the wearer 600. The bioelectrical measurements include electrocardiograms (ECG), electrogastrograms (EGG), electroencephalograms (EEG), and electromyography (EMG). The bioimpedance measurements include plethysmography (e.g., for respiration), body composition (e.g., hydration, fat, etc.), and electroimpedance tomography (EIT). The biomagnetic measurements include magnetoneurograms (MNG), magnetoencephalography (MEG), magnetogastrogram (MGG), magnetocardiogram (MCG). The biochemical measurements include glucose/lactose measurements which may be performed using chemical analysis of the wearer 600’s sweat. The biomechanical measurements include blood pressure. The bioacoustics measurements include phonocardiograms (PCG). The biooptical measurements include orthopantomogram (OPG). The biothermal measurements include skin temperature and core body temperature measurements.

Referring to Figures 3 to 7, there is shown an example system 10 according to aspects of the present disclosure. The system 10 comprises an electronics module 100, a wearable article in the form of a garment 200, and a user electronic device 300. The garment 200 is worn by a user who in this embodiment is the wearer 600 of the garment 200.

The electronics module 100 is arranged to integrate with sensing units 400 incorporated into the garment 200 to obtain signals from the sensing units 400. The electronics module 100 and the wearable article 200 and including the sensing units 400 comprise a wearable assembly 500.

The sensing units 400 comprise one or more sensors 209, 211 with associated conductors 203, 207 and other components and circuitry. The electronics module 100 is further arranged to wirelessly communicate data to the user electronic device 300. Various protocols enable wireless communication between the electronics module 100 and the user electronic device 300. Example communication protocols include Bluetooth ®, Bluetooth ® Low Energy, and near-field communication (NFC).

The garment 200 has an electronics module holder in the form of a pocket 201 . The pocket 201 is sized to receive the electronics module 100. When disposed in the pocket 201 , the electronics module 100 is arranged to receive sensor data from the sensing units 400. The electronics module 100 is therefore removable from the garment 200.

The present disclosure is not limited to electronics module holders in the form pockets.

The electronics module 100 may be configured to be releasably mechanically coupled to the garment 200. The mechanical coupling of the electronic module 100 to the garment 200 may be provided by a mechanical interface such as a clip, a plug and socket arrangement, etc. The mechanical coupling or mechanical interface may be configured to maintain the electronic module 100 in a particular orientation with respect to the garment 200 when the electronic module 100 is coupled to the garment 200. This may be beneficial in ensuring that the electronic module 100 is securely held in place with respect to the garment 200 and/or that any electronic coupling of the electronic module 100 and the garment 200 (or a component of the garment 200) can be optimized. The mechanical coupling may be maintained using friction or using a positively engaging mechanism, for example.

Beneficially, the removable electronic module 100 may contain all the components required for data transmission and processing such that the garment 200 only comprises the sensing units 400 e.g. the sensors 209, 211 and communication pathways 203, 207. In this way, manufacture of the garment 200 may be simplified. In addition, it may be easier to clean a garment 200 which has fewer electronic components attached thereto or incorporated therein. Furthermore, the removable electronic module 100 may be easier to maintain and/or troubleshoot than embedded electronics. The electronic module 100 may comprise flexible electronics such as a flexible printed circuit (FPC).

The electronic module 100 may be configured to be electrically coupled to the garment 200.

Referring to Figure 4, there is shown a schematic diagram of an example of the electronics module 100 of Figure 1. A more detailed block diagram of the electronics components of electronics module 100 and garment are shown in Figure 5.

The electronics module 100 comprises an interface 101 , a controller 103, a power source 105, and one or more communication devices which, in the exemplar embodiment comprises a first antenna 107, a second antenna 109 and a wireless communicator 159. The electronics module 100 also includes an input unit such as a proximity sensor or a motion sensor 111 , for example in the form of an inertial measurement unit (IMU).

The electronics module 100 also includes additional peripheral devices that are used to perform specific functions as will be described in further detail herein.

The interface 101 is arranged to communicatively couple with the sensing unit 400 of the garment 200. The sensing unit 400 comprises - in this example - the two sensors 209, 211 coupled to respective first and second electrically conductive pathways 203, 207, each with respective termination points 213, 215. The interface 101 receives signals from the sensors 209, 211 . The controller 103 is communicatively coupled to the interface 101 and is arranged to receive the signals from the interface 101 for further processing.

The interface 101 of the embodiment described herein comprises first and second contacts 163, 165 which are arranged to be communicatively coupled to the termination points 213, 215 the respective first and second electrically conductive pathways 203, 207. The coupling between the termination points 213, 215 and the respective first and second contacts 163, 165 may be conductive or a wireless (e.g. inductive) communication coupling.

In this example the sensors 209, 211 are used to measure electropotential signals such as electrocardiogram (ECG) signals, although the sensors 209, 211 could be configured to measure other biosignal types as also discussed above. In this embodiment, the sensors 209, 211 are configured for so-called dry connection to the wearer’s skin to measure ECG signals.

The power source 105 may comprise a plurality of power sources. The power source 105 may be a battery. The battery may be a rechargeable battery. The battery may be a rechargeable battery adapted to be charged wirelessly such as by inductive charging. The power source 105 may comprise an energy harvesting device. The energy harvesting device may be configured to generate electric power signals in response to kinetic events such as kinetic events 10 performed by the wearer 600 of the garment 200. The kinetic event could include walking, running, exercising or respiration of the wearer 600. The energy harvesting material may comprise a piezoelectric material which generates electricity in response to mechanical deformation of the converter. The energy harvesting device may harvest energy from body heat of the wearer 600 of the garment. The energy harvesting device may be a thermoelectric energy harvesting device. The power source 105 may be a super capacitor, or an energy cell.

The first antenna 107 is arranged to communicatively couple with the user electronic device 300 using a first communication protocol. In the example described herein, the first antenna 107 is a passive tag such as a passive Radio Frequency Identification (RFID) tag or Near Field Communication (NFC) tag. These tags comprise a communication module as well as a memory which stores the information, and a radio chip. The user electronic device 300 is powered to induce a magnetic field in an antenna of the user electronic device 300. When the user electronic device 300 is placed in the magnetic field of the communication module antenna 107, the user electronic device 300 induces current in the communication module antenna 107. This induced current triggers the electronics module 100 to retrieve the information from the memory of the tag and transmit the same back to the user electronic device 300.

In an example operation, the user electronic device 300 is brought into proximity with the electronics module 100. In response to this, the electronics module 100 is configured to energize the first antenna 107 to transmit information to the user electronic device 300 over the first wireless communication protocol. Beneficially, this means that the act of the user electronic device 300 approaching the electronics module 100 energizes the first antenna 107 to transmit the information to the user electronic device 300.

The information may comprise a unique identifier for the electronics module 100. The unique identifier for the electronics module 100 may be an address for the electronics module 100 such as a MAC address or Bluetooth ® address.

The information may comprise authentication information used to facilitate the pairing between the electronics module 100 and the user electronic device 300 over the second wireless communication protocol. This means that the transmitted information is used as part of an out of band (OOB) pairing process.

The information may comprise application information which may be used by the user electronic device 300 to start an application on the user electronic device 300 or configure an application running on the user electronic device 300. The application may be started on the user electronic device 300 automatically (e.g. without wearer 600 input). Alternatively, the application information may cause the user electronic device 300 to prompt the wearer 600 to start the application on the user electronic device. The information may comprise a uniform resource identifier such as a uniform resource location to be accessed by the user electronic device, or text to be displayed on the user electronic device for example. It will be appreciated that the same electronics module 100 can transmit any of the above example information either alone or in combination. The electronics module 100 may transmit different types of information depending on the current operational state of the electronics module 100 and based on information it receives from other devices such as the user electronic device 300.

The second antenna 109 is arranged to communicatively couple with the user electronic device 300 over a second wireless communication protocol. The second wireless communication protocol may be a Bluetooth ® protocol, Bluetooth ® 5 or a Bluetooth ® Low Energy protocol but is not limited to any particular communication protocol. In the present embodiment, the second antenna 109 is integrated into controller 103. The second antenna 109 enables communication between the user electronic device 300 and the controller 100 for configuration and set up of the controller 103 and the peripheral devices as may be required. Configuration of the controller 103 and peripheral devices utilises the Bluetooth ® protocol.

The wireless communicator 159 may be an alternative, or in addition to, the first and second antennasl 07, 109.

Other wireless communication protocols can also be used, such as used for communication over: a wireless wide area network (WWAN), a wireless metro area network (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN), Bluetooth ® Low Energy, Bluetooth ® Mesh, Thread, Zigbee, IEEE 802.15.4, Ant, a Global Navigation Satellite System (GNSS), a cellular communication network, or any other electromagnetic RF communication protocol. The cellular communication network may be a fourth generation (4G) LTE, LTE Advanced (LTE-A), LTE Cat-M1 , LTE Cat-M2, NB-loT, fifth generation (5G), sixth generation (6G), and/or any other present or future developed cellular wireless network.

The electronics module 100 includes configured a clock unit in the form of a real time clock (RTC) 153 coupled to the controller 103 and, for example, to be used for data logging, clock building, time stamping, timers, and alarms. As an example, the RTC 153 is driven by a low frequency clock source or crystal operated at 32.768 Hz.

The electronics module 100 also includes a location device 161 such as a GNSS (Global Navigation Satellite System) device which is arranged to provide location and position data for applications as required. In particular, the location device 161 provides geographical location data at least to a nation state level. Any device suitable for providing location, navigation or for tracking the position could be utilised. The GNSS device may include device may include Global Positioning System (GPS), BeiDou Navigation Satellite System (BDS) and the Galileo system devices.

The power source 105 in this example is a lithium polymer battery 105. The battery 105 is rechargeable and charged via a USB C input 131 of the electronics module 100. Of course, the present disclosure is not limited to recharging via USB and instead other forms of charging such as inductive of far field wireless charging are within the scope of the present disclosure. Additional battery management functionality is provided in terms of a charge controller 133, battery monitor 135 and regulator 147. These components may be provided through use of a 30 dedicated power management integrated circuit (PMIC).

The USB C input 131 is also coupled to the controller 131 to enable direct communication with the controller 103 with an external device if required.

The controller 103 is communicatively connected to a battery monitor 135 so that that the controller 103 may obtain information about the state of charge of the battery 105.

The controller 103 has an internal memory 167 and is also communicatively connected to an external memory 143 which in this example is a NAND Flash memory. The memory 143 is used to for the storage of data when no wireless connection is available between the electronics module 100 and a user electronic device 300. The memory 143 may have a storage capacity of at least 1 GB and preferably at least 2 GB.

The electronics module 100 also comprises a temperature sensor 145 and a light emitting diode 147 for conveying status information. The electronic module 100 also comprises conventional electronics components including a power-on-reset generator 149, a development connector 151 , the real time clock 153 and a PROG header 155.

Additionally, the electronics module 100 may comprise a haptic feedback unit 157 for providing a haptic (vibrational) feedback to the wearer 600.

The wireless communicator 159 may provide wireless communication capabilities for the garment 200 and enables the garment to communicate via one or more wireless communication protocols to a remote server 700. Wireless communications may include: a wireless wide area network (WWAN), a wireless metro area network (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN), Bluetooth ® Low Energy, Bluetooth ® Mesh, Bluetooth ® 5, Thread, Zigbee, IEEE 802.15.4, Ant, a near field communication (NFC), Near Field Magnetic Induction, a Global Navigation Satellite System (GNSS), a cellular communication network, or any other electromagnetic RF communication protocol. The cellular communication network may be a fourth generation (4G) LTE, LTE Advanced (LTE-A), LTE Cat-M1 , LTE Cat-M2, NB-loT, fifth generation (5G), sixth generation (6G), and/or any other present or future developed cellularwireless network.

The electronics module 100 may additionally comprise a Universal Integrated Circuit Card (UICC) that enables the garment to access services provided by a mobile network operator (MNO) or virtual mobile network operator (VMNO). The UICC may include at least a read-only memory (ROM) configured to store an MNO or VMNO profile that the garment can utilize to register and interact with an MNO or VMNO. The UICC may be in the form of a Subscriber Identity Module (SIM) card. The electronics module 100 may have a receiving section arranged to receive the SIM card. In other examples, the UICC is embedded directly into a controller of the electronics module 100. That is, the UICC may be an electronic/embedded UICC (eUICC). A eUICC is beneficial as it removes the need to store a number of MNO profiles, i.e. electronic Subscriber Identity Modules (eSIMs). Moreover, eSIMs can be remotely provisioned to garments. The electronics module 100 may comprise a secure element that represents an 35 embedded Universal Integrated Circuit Card (eUICC). In the present disclosure, the electronics module may also be referred to as an electronics device or unit. These terms may be used interchangeably.

The controller 103 is connected to the interface 101 via an analog-to-digital converter (ADC) front end 139 and an electrostatic discharge (ESD) protection circuit 141 . The ADC front end 139 may be referred to as a sensing component.

Figure 6 is a schematic illustration of the component circuitry for the ADC front end 139.

In the example described herein, the ADC front end 139 is an integrated circuit (IC) chip which converts the raw analogue biosignal received from the sensors 209, 211 into a digital signal for further processing by the controller 103. ADC IC chips are known, and any suitable one can be utilised to provide this functionality. ADC IC chips for ECG applications include, for example, the MAX30003 chip produced by Maxim Integrated Products Inc.

The ADC front end 139 includes an input 169 and an output 171 .

Raw biosignals from the electrodes 209, 211 are input to the ADC front end 139, where received signals are processed in an ECG channel 175 and subject to appropriate filtering through high pass and low pass filters for static discharge and interference reduction as well as for reducing bandwidth prior to conversion to digital signals. The reduction in bandwidth is important to remove or reduce motion artefacts that give rise to noise in the signal due to movement of the sensors 209, 211.

The output digital signals may be decimated to reduce the sampling rate prior to being passed to a serial programmable interface (SPI) 173 of the ADC front end 139. Signals are output to the controller 103 via the SPI 173.

The digital signal values output to the controller 103 are stored in a FIFO data buffer. The controller 103 performs operations to detect R-peaks from the digital signal values. The operations are performed in realtime while the ADC front end 139 are outputting new digital signals to the controller 103.

ADC front end IC chips suitable for ECG applications may be configured to determine information from the input biosignals such as heart rate and the QRS complex and including the R-R interval. Support circuitry 177 provides base voltages for the ECG channel 175. Although this is no required in all examples, as these determinations such as for identifying peaks in the heartrate signal may be performed by the controller 103 of the electronics module 100 or the user electronic device 300 as explained below.

Signals are output to the controller 103 via the SPI 173. The signals may be digital heartrate values obtained by the ADC front end 139.

The controller 103 can also be configured to apply digital signal processing (DSP) to the digital signal from the ADC front end 139. The DSP may include noise filtering additional to that carried out in the ADC front end 139 and ay also include additional processing to determine further information about the signal from the ADC front end 139.

The controller 103 is configured to send the biosignals to the user electronic device 300 using either of the first antenna 107, second antenna 109, or wireless communicator 159. The biosignals sent to the user electronic device 300 in this example comprise digital heartrate values representative of the heartrate signal of the user.

The user electronic device 300 in the example of Figure 7 is in the form of a mobile phone or tablet and comprises a controller 305, a memory 304 (which may be internal to the controller 305), a wireless communicator 307, a display 301 , a user input unit 306, a capturing device in the form of a camera 303 and an inertial measurement unit (IMU) 309. The controller 305 provides overall control to the user electronic device 300.

The user input unit 306 receives inputs from the user such as a user credential.

The memory 304 stores information for the user electronic device 300.

The display 301 is arranged to display a user interface for applications operable on the user electronic device 300.

The IMU 309 provides motion and/or orientation detection and may comprise an accelerometer and optionally one or both of a gyroscope and a magnetometer.

The user electronic device 300 may also include a biometric sensor. The biometric sensor may be used to identify a user or users of device based on unique physiological features. The biometric sensor may be: a fingerprint sensor used to capture an image of a user's fingerprint; an iris scanner or a retina scanner configured to capture an image of a user's iris or retina; an ECG module used to measure the user’s ECG; or the camera of the user electronic arranged to capture the face of the user. The biometric sensor may be an internal module of the user electronic device. The biometric module may be an external (stand-alone) device which may be coupled to the user electronic device by a wired or wireless link.

The controller 305 is configured to launch an application which is configured to display insights derived from the biosignal data processed by the ADC front end 139 of the electronics module 100, input to electronics module controller 103, and then transmitted from the electronics module 100. The transmitted data is received by the wireless communicator 307 of the user electronic device 300 and input to the controller 305.

Insights include, but are not limited to, an ECG signal trace i.e. the QRS complex, heart rate, respiration rate, core temperature but can also include identification data for the wearer 600 using the wearable assembly 500.

The display 301 may be a presence-sensitive display and therefore may comprise the user input unit 306. The presence-sensitive display may include a display component and a presence-sensitive input component. The presence sensitive display may be a touch-screen display arranged as part of the user interface.

User electronic devices in accordance with the present invention are not limited to mobile phones or tablets and may take the form of any electronic device which may be used by a user to perform the methods according to aspects of the present invention. The user electronic device 300 may be a electronics module such as a smartphone, tablet personal computer (PC), mobile phone, smart phone, video telephone, laptop PC, netbook computer, personal digital assistant (PDA), mobile medical device, camera or wearable device. The user electronic device 300 may include a head-mounted device such as an Augmented Reality, Virtual Reality or Mixed Reality head-mounted device. The user electronic device 300 may be desktop PC, workstations, television apparatus or a projector, e.g. arranged to project a display onto a surface.

In use, the electronics module 100 is configured to receive raw biosignal data from the sensors 209, 211 and which are coupled to the controller 103 via the interface 101 and the ADC front end 139 for further processing and transmission to the user electronic device 300 as described above. The controller 103 determines inter-beat interval (IBI) values from the heartrate signals and uses these to obtain values of the heartrate. The IBI values represent the time between successive heartbeats. The heartrate is given as a measure of the number of heartbeats per minute.

Figure 8 provides a flow diagram for an example method performed by the controller 103 for detecting R- peaks from the digital signals stored in the FIFO data buffer.

In step S101 , the controller 103 reads signal values from the data buffer. Each of the signal values is a value that represents the amplitude of the ECG signal at a particular time point.

In step S102, the controller 103 detrends the signal values so as to remove baseline wander and/or other low frequency components. In an example operation, the controller 103 calculates the trend in the signal values and then subtracts the calculated trend from each of the signal values.

Calculating the trend comprises identifying the maximum and minimum signal values read from the data buffer. The maximum signal value is added to a buffer that stores the maximum signal values obtained over time. The minimum signal value is added to a buffer that stores the minimum signal values obtained over time. The current trend is then calculated by calculating the average of the maximum value stored in the buffer of maximum signal values and the minimum value stored in the buffer of minimum signal values.

As explained above, the detrended signal values are calculated by subtracting the calculated current trend from each of the signal values. The detrended signal values are added to a FIFO detrended signal buffer.

In step S103, the detrended signal values are filtered. The filtering is performed to remove components from the signal that do not resemble R-peaks. A bandpass filter centred around the frequency associated with the shape and width of the R-peak can be used to perform this task.

Some filtering approaches use a bandpass filter with a central frequency in the range of 17 to 19 Hz. HR or FIR filters may be used, however, they are generally not effective due to ripples and lobes that may be present around the R-peaks in the ECG signal. The interaction between these secondary peaks and other components of the ECG signal can lead to ambiguity in the identity of the actual main peak.

Preferred bandpass filtering approaches analyse a signal of the instantaneous amplitude associated with the R-peak frequency. These approaches exploit the fact that R-peaks are approximately symmetrical features which means that the location of the peak in the spectral amplitude is normally close to the location of the centre of the R-peak itself. The signal of instantaneous amplitude can be obtained using a complex filter and by calculating the absolute magnitude of the real and imaginary component for each filtered signal value.

In a preferred implementation, the complex filter used is a complex Morlet wavelet. The Morlet wavelet has optimal frequency resolution due to its Gaussian envelope. The Morlet wavelet is also useful because it is symmetrical across the y-axis which means that only half of the filter coefficients need to be stored in RAM.

The filtered signal values are added to a FIFO filtered signal buffer.

In step S104, the controller 103 determines whether at least N filtered signal values have been obtained. Here, N is a number that may be selected by the skilled person as desired to ensure that there are likely to be a certain desired number of peaks within the window of filtered signal values. For example, N may be selected such that the filtered signal buffer contains at least 4 seconds of data to ensure that there are at least 2 peaks in any window. The number N will depend on the sampling rate of the signal values provided to the controller 103. For example, if the sampling rate is 512Hz and at least 4 seconds of data are required, then N = 2048. Other values of N are within the scope of the present disclosure.

If less than N samples of filtered signal values have been obtained then the method returns to step S101 so that additional samples are gathered, filtered, and added to the filtered signal buffer. Steps S101 to S104 are repeated until the N signal values are obtained.

If N or more samples of the filtered signal values have been obtained, the method proceeds to step S105.

In step S105, the controller 103 detects peaks in the filtered signal values. At this stage, the controller 103 is identifying any peaks, including small and spurious peaks, in the filtered signal values. The peak detection process identifies local maxima in the signal values. Peak detection can be performed by simply looking for negative gradients in the filtered signal values.

In step S106, the controller 103 removes detected peaks that have an amplitude less than a threshold level. The thresholding process is intended to remove peaks that are not R-peaks in the ECG signal. The thresholding level is determined according to an adjustable threshold value multiplied by the average spectral power for the filtered signal values. Using the average spectral power enables the thresholding level to adapt based on the power of the signal.

One or more additional steps may be performed such as to check the remaining peaks after step S106 and remove or compensate for spurious remaining peaks. These spurious peaks may be due to noise spikes, ectopic beats or other ECG components. An example process for detecting spurious peaks is disclosed in Mateo J, Laguna P. Analysis of heartrate variability in the presence of ectopic beats using the heart timing signal. IEEE Trans Biomed Eng. 2003 Mar;50(3):334-43.

The detected R-peaks are used to form inter-beat interval (IBI) values representing the time between successive heartbeats. A heartrate value is determined by calculating an average IBI value for a time window (e.g. 4 seconds) and by dividing 60000 by the average IBI value in milliseconds to obtain the heartrate value. The heartrate value along with a timestamp representative of the time window form a pair of values. The timestamp may represent the start of the time window, the end of the time window or a position between the start and the end of the time window.

Generally, the time windows are of a duration of N seconds where N is a number that may be selected by the skilled person as desired to ensure that there are likely to be a certain desired number of peaks in the series of heartrate values for use in determining IBI values. In some examples, N is greater than or equal to 4 such that the series of heartrate values represent 4 seconds of the heartrate signal. 4 seconds is generally sufficient to ensure that there are at least 2 peaks representative of different heartbeats in the time window. Other values of N are within the scope of the present disclosure.

The controller 103 controls the communicator 109 to transmit pairs of values each comprising a heartrate value and a timestamp to the user electronics device 300. The pairs of values are typically transmitted in real time as they are calculated by the controller 103.

The communicator 307 of the user electronics device 300 receives the pairs of values and stores them in the memory 304 for display by the display 301 and/or analysis by the controller 305. The analysis can include determining heart health, recovery level, stress level, or other physiological metrics which use the heartrate, optionally alongst other metrics such as heartrate variability, respiration rate, and body temperature.

Referring to Figure 9, there is shown a graph which plots a plurality of pairs of values (T 1 , H1), (T2, H2), (T3, H3), (T4, H4), (T5, H5). Each of the plurality of pairs of values include a timestamp and a heartrate value associated with the timestamp. The heartrate is the y-axis of the graph and time is the x-axis of the graph.

The plurality of pairs of values include a first valid pair of values (T 1 , H 1 ) and a second valid pair of values (T5, H5). The valid pairs of values are determined to satisfy one or more validity criterions. The valid pairs of values represent heartrate values (H) that would be expected at their corresponding timestamps (T).

The plurality of pairs of values further include intermediate pairs of values (T2, H2), (T3, H3), (T4, H4) with timestamps that are between the timestamp T1 for the first valid pair of values and the timestamp T5 for the second valid pair of values.

The intermediate pairs of values (T2, H2), (T3, H3), (T4, H4) do not satisfy one or more validity criterion. In particular, the intermediate pairs of values (T2, H2), (T3, H3), (T4, H4) represent rates of change of heartrate from the heartrate H1 of the first valid pair of values (T1 , H1) that are outside of an allowable range. This means that the heartrate values H2, H3, H4 do not correspond to values that would be expected at their respective timestamps T2, T3, T4. A heartrate value may also be determined to not satisfy a validity criterion if its heart value is above a maximum threshold value or below a minimum threshold value.

The erroneous intermediate heartrate values H2, H3, H4 may be caused by signal noise due to movement of the heart rate sensing electrodes of the wearable article from the skin surface due to user motion, for example. Detecting and subsequently correcting the heartrate values H2, H3, H4 can improve a resultant display of the heartrate to the user as well as improve the accuracy of any psychological metrics that are determined using heartrate values.

In an example operation according to the present disclosure, the controller 305 of the user electronic device 300 receives the plurality of pairs of values (T1 , H1), (T2, H2), (T3, H3), (T4, H4), (T5, H5) from the electronics module 100 in sequence.

The pair of values (T 1 , H1) is received first. The controller 305 determines that the pair of values (T1 , H1) satisfy a validity criterion and stores the pair of values (T 1 , H 1 ) in memory as a first valid pair of values (T 1 , H1).

The pair of values (T2, H2), (T3, H3), (T4, H4) are subsequently received. For each of these pair of values, the controller 305 determines that a validity criterion is not satisfied. The controller 305 discards the heartrate values H2, H3, H4 and stores the timestamps T2, T3, T4 as intermediate timestamps. Only storing the timestamp values reduces the amount of information that needs to be stored and subsequently accessed from memory.

The pair of values (T5, H5) is received next. The controller 305 determines that the pair of values (T5, H5) satisfy a validity criterion and stores the pair of values (T5, H5) in memory as a second valid pair of values (T5, H5).

The controller 305 then uses the first valid pair of values (T 1 , H1) and the second valid pair of values (T5, H5) to generate corrected heartrate values H2’, H3’, H4’ for the timestamps T2, T3, T4.

The pair of values (T5, H5) may subsequently be set as a first valid pair of values (T5, H5) such that subsequently received pairs of values may be corrected in a similar process. This is shown in Figures 13 and 14.

Referring to Figure 10, there is shown a graph which plots a plurality of pairs of values (T 1 , H1) (T2, H2’), (T3, H3’), (T4, H4’), (T5, H5) received from the electronics module 100 following the correction of the erroneous heartrate values H2, H3, H4 to corrected heartrate values H2’, H3’, H4’ by the controller 305. The heartrate is the y-axis of the graph and the time is the x-axis of the graph.

The corrected heartrate values H1 , H2’, H3’, H4’, H5 generally follow the dashed line ‘A’ which represents how a heartrate trace derived from the heartrate values H1 , H2’, H3’, H4’, H5 may be displayed to a user.

Referring to Figure 11 , there is shown a flow diagram for an example method of detecting erroneous heartrate values. In step S201 , the controller 305 obtains a pair of values. The pair of values comprise a heartrate value for the heartrate signal and a timestamp representative of the time window that the first heartrate value relates to.

In step S202, the controller 305 determines whether the pair of values satisfy a validity criterion.

If a valid pair of values has not yet been identified, for example if no previous pair of values have been received, the controller 305 determines that the pair of values satisfy a validity criterion by comparing the heartrate value to a maximum threshold value representing a maximum expected heartrate value and a minimum threshold value representing a minimum expected heartrate. If the heartrate value is less than the maximum threshold value and greater than the minimum threshold value, then it is determined to be valid. If a valid pair of values has previously been identified, then the controller 305 determines that the pair of values satisfy a validity criterion by considering the rate of change in heartrate value from the previous valid pair of values to the current pair of values.

In a first operation, the controller 305 determines the difference between current heartrate value and the heartrate value for the previous valid pair of values.

In a second operation, the controller 305 determines the difference between the current timestamp and the timestamp for the previous valid pair of values. In a third operation, the controller 305 divides the difference between the current heartrate value and the heartrate value for the previous valid pair of values by the difference between the current timestamp and the timestamp for the previous valid pair of values. This determines the rate of change of the heartrate from the timestamp to the previous valid pair of values to the timestamp for the current pair of values. In a fourth operation, the controller 305 compares the result of the third operation to a threshold value.

If the result is greater than the threshold value, then the heartrate value for the current pair of values would be determined to not satisfy the validity criterion. This means that the rate of increase or decrease of the heartrate from the timestamp for the previous valid pair of values to the current pair of values is greater than a predetermined acceptable amount.

If the result is less than the threshold value, then the heartrate value for the current pair of values may be determined to not satisfy the validity criterion. The threshold values may be any appropriate values set by a medical professional for example. The threshold values may be set according to factors such as the age, gender, weight, height, and lifestyle of the user. The present disclosure is not limited to any particular values. The threshold value may be, for example, 50 bpm/second, 40 bpm/second, or 30 bpm/second. The controller 305 may additionally compare the heartrate value to a maximum threshold value representing a maximum expected heartrate value and a minimum threshold value representing a minimum expected heartrate. If the heartrate value is greater than the maximum threshold value or less than the minimum threshold value then it is determined to not satisfy the validity criterion.

The maximum threshold value may be, for example, 220 bpm. The minimum threshold value may be, for example, 30 bpm. The threshold values may be any appropriate values set by a medical professional for example. The threshold values may be set according to factors such as the age, gender, weight, height, and lifestyle of the user. The present disclosure is not limited to any particular values.

The maximum threshold value may be the maximum heartrate for the user. Examples of how the maximum heartrate may be determined are provided below in the discussion surrounding Figure 17.

If, in step S202, the controller 305 determines that the pair of values satisfy a validity criterion, then the controller 305 proceeds to step S203.

In step S203, the controller 305 sets the pair of values as a valid pair of values.

In step S204, the controller 305 uses the valid pair of values to correct an invalid pair of values.

If, in step S202, the controller 305 determines that the pair of values do not satisfy a validity criterion, then the controller 305 proceeds to step S204.

In step S204, the controller 305 sets the pair of values as an invalid pair of values. This may mean that the heartrate value is discarded and only the timestamp is retained.

In step S205, the controller 305 corrects the invalid pair of values using a valid pair of values.

Referring again to Figure 9, in this example, there are no valid pair of values received prior to the first pair of values (T 1 , H 1 ) . Therefore, the heartrate value H1 is compared to the maximum threshold value and the minimum threshold value. The heartrate value H1 is less than the maximum threshold value and greater than the minimum threshold value and so is determined to be a valid heartrate value. The first pair of values (T 1 , H1) is therefore set as a first valid pair of values (T 1 , H1).

The pairs of values (T2, H2), (T3, H3), (T4, H4) are determined not to satisfy the validity criterion as the rate of decrease of the heartrate from the first pair of valid values (T 1 , H1) is greaterthan a predetermined acceptable amount. That is, the rate of change is considered to be greater than medically possible. The pairs of values (T2, H2), (T3, H3), (T4, H4) are therefore determined to be invalid.

The pair of values (T5, H5) is determined to satisfy the validity criterion as the rate of increase of the heartrate from the first pair of valid values (T1 , H 1 ) is less than or equal to the predetermined acceptable amount. The pair of values (T5, H5) is therefore set as a second valid pair of values. The first pair of valid values (T 1 , H1) and the second pair of valid values (T2, H2) are used to correct the intermediate heartrate values H2, H3, H4.

Referring to Figure 12, there is shown a flow diagram for an example method of correcting erroneous heartrate values. The erroneous heartrate values may be the intermediate heartrate values H2, H3, H4 in Figure 9.

In step S301 , the controller 305 obtains a first pair of valid values (T 1 , H1). The first pair of valid values comprise a heartrate value (H1) for the heartrate signal and a timestamp (T1) representative of the time window that the heartrate value relates to.

In step S302, the controller 305 obtains a second pair of valid values (T5, H5). The second pair of values comprise a heartrate value (H5) for the heartrate signal and a timestamp (T5) representative of the time window that the heartrate value relates to. The timestamp (T5) for the second pair of valid values (T5, H5) occurs after the timestamp (T1) for the first pair of valid values (T 1 , H1).

In step S303, the controller 305 obtains at least one intermediate timestamp (T2, T3, T4) that occurs between the timestamp (T1) for the first pair of valid values (T 1 , H 1 ) and the timestamp (T5) for the second pair of valid values (T5, H5).

In step S304, the controller 305 sets a heartrate value for each of the at least one intermediate timestamps (T2, T3, T4) using the first and second pair of values (T 1 , H1), (T5, H5).

In an example operation, the controller 305 uses the first and second pair of values (T 1 , H1), (T5, H5). to determine the coefficients a₀, £¾, ... £ of a polynomial function of the form f(t ) = a_ntⁿ + a^t^71-1 H - 1- + a₀, where t denotes a timestamp value. The polynomial function therefore uses time as an independent variable and heartrate as a dependent variable.

The intermediate timestamps are then input to the polynomial function f(t ) to obtain corrected heartrate values H2’, H3’, H4’.

In a preferred example, the polynomial function is a linear function of the form f(t ) =

a₀. The present disclosure is, however, not limited to linear functions. Any polynomial function having a degree greater than or equal to 1 may be selected as preferred by the skilled person.

In this example, the controller 305 determines the coefficient, a by dividing the difference between the heartrate values (H1 , H5) for the first and second valid pairs of values (T 1 , H1), (T5, H5) by the difference between the timestamps (T 1 , T5) for the first and second valid pairs of values (T 1 , H1), (T5, H5).

In this example, the controller 305 determines the coefficient, a₀, by subtracting the product of % and the timestamp (T1) forthe first valid pair of values (T1 , H1) from the heartrate value (H1) forthe first valid pair of values (T 1 , H1). Referring again to Figure 10, the corrected heartrate values H2’, H3’, H4’ linearly increases from the heartrate value H1 for the first valid pair of values (T 1 , H1) to the heartrate value H5 for the second valid pair of values (T5, H5) according to the function f(t ) = a_±t + a₀ defined above.

Referring to Figure 13, there is shown a graph which plots a plurality of pairs of values (T 1 , H1)-(T15, H15) Each of the plurality of pairs of values include a timestamp and a heartrate value associated with the timestamp. The heartrate is the y-axis of the graph and time is the x-axis of the graph.

The pairs of values (T1 , H1), (T5, H5), (T7, H7), (T8, H8), (T9, H9), (T10, H10), (T11 , H11), (T15, H15) are valid pairs of values that are determined to satisfy a validity criterion.

The pairs of values (T2, H2), (T3, H3), (T4, H4), (T6, H6), (T12, H12), (T13, H13), (T14, H14) are invalid pairs of values that are determined to not satisfy a validity criterion.

The pairs of values (T2, H2), (T3, H3), (T4, H4) are corrected using the valid pairs of values (T1 , H1) and (T5, H5). The pair of values (T1 , H1) forms a first valid pair of values (T 1 , H1) with a timestamp T1 occurring before the intermediate timestamps T2, T3, T4 and the pair of values (T5, H5) forms a second valid pair of values (T5, H5) with a timestamp T5 occurring after the intermediate timestamps T2, T3, T4.

The first and second valid pair of values (T1 , H1), (T5, H5) are used to determine the coefficients of a polynomial function as described previously. The intermediate timestamps T2, T3, T4 are then input into the polynomial function to obtain corrected heartrate values H2’, H3’, H4’.

The pair of values (T6, H6) is corrected using the valid pairs of value (T5, H5), (T7, H7). The pair of values (T5, H5) forms a first valid pair of values (T5, H5) with a timestamp T5 occurring before the intermediate timestamp T6 and the pair of values (T7, H7) forms a second valid pair of values (T7, H7) with a timestamp T7 occurring after the intermediate timestamp T6.

The first and second valid pair of values (T5, H5), (T7, H7) are used to determine the coefficients of a polynomial function as described previously. The intermediate timestamp T6 is then input into the polynomial function to obtain corrected heartrate value H6’.

The pairs of values (T12, H12), (T13, H13), (T14, H14) are corrected using the valid pairs of values (T11 , H11) and (T15, H15). The pair of values (T11 , H11) forms a first valid pair of values (T11 , H11) with a timestamp T11 occurring before the intermediate timestamps T12, T13, T14 and the pair of values (T15, H15) forms a second valid pair of values (T15, H15) with a timestamp T15 occurring after the intermediate timestamps T12, T13, T14.

The first and second valid pair of values (T11 , H11), (T15, H15) are used to determine the coefficients of a polynomial function as described previously. The intermediate timestamps T12, T13, T14 are then input into the polynomial function to obtain corrected heartrate values H12’, H13’, H14’.

Referring to Figure 14, there is shown a graph which plots a plurality of pairs of values (T 1 , H1) (T2, H2’), (T3, H3’), (T4, H4’), (T5, H5), (T6, H6’), (T7, H7), (T8, H8), (T9, H9), (T10, H10), (T11 , H11), (T12, H12’), (T13, H13’), (T14, H14’), (T15, H15) received from the electronics module 100 following the correction of the erroneous heartrate values H2, H3, H4, H6, H12, H13, H14 to corrected heartrate values H2’, H3’, H4’, H6’, H12’, H13’, H14’ by the controller 305. The heartrate is the y-axis of the graph and the time is the x- axis of the graph.

The corrected heartrate values H1 , H2’, H3’, H4’, H5 generally follow the dashed line ‘A’ which represents how a heartrate trace derived from the heartrate values H1 , H2’, H3’, H4’, H5 may be displayed to a user. The corrected heartrate values H5, H6’, H7 generally follow the dashed line 'B'. The corrected heartrate values H7, H8, H9, H10, H11 generally follow the dashed line ‘C. The corrected heartrate values H11 , H12’, H13’, H14’, H15 generally follow the dashed line O’.

Referring to Figure 15, there is shown a flow diagram for an example method of correcting heartrate values derived from a heartrate signal according to aspects of the present disclosure. The method is performed by a computing apparatus 300 comprising a processor (e.g. a component of controller 305), a memory 304 and a communicator 307.

Step S401 comprises the processor 305 obtaining from the memory 304, a first valid pair of values comprising a heartrate value for the heartrate signal and a timestamp representative of the time window that the first heartrate value relates to.

Step S402 comprises the processor 305 receiving from the communicator 307, a pair of values comprising a heartrate value forthe heartrate signal and a timestamp representative of the time window that the second heartrate value relates to, the timestamp occurring after the timestamp for the first valid pair of values obtained from the memory 304 in step S401 .

Step S403 comprises the processor 305 determining whether the received pair of values satisfy a validity criterion.

If the received pair of values satisfy a validity criterion then the received pair of values form a second valid pair of values and the method proceeds to step S404.

In step S404, the processor 305 uses the first and second valid pair of values to create at least one intermediate pair of values. Each of the intermediate pairs of values comprises a heartrate value and a timestamp representative of the time window that the heartrate value belongs to. Each of the timestamps for the intermediate pairs of values occurs between the timestamp for the first valid pair of values and the timestamp for the second valid pair of values.

Referring to Figure 16, there is shown a swim-lane diagram of an example method performed by a system for correcting heartrate values derived from a heartrate signal. The system comprises an electronics module 100 (Figure 5) for a wearable article.

The electronics module 100 comprises a processor 103, a memory 167, a communicator 109 and a sensing component 139. The computing apparatus 300 comprising a processor 305, a memory 304 and a communicator 307.

Step S501 comprises obtaining, by the processor 305 of the computing apparatus 300 from the memory 304 of the computing apparatus 300, a first valid pair of values comprising a heartrate value for the heartrate signal and a timestamp representative of the time window that the first heartrate value relates to.

Step S502 comprises receiving, by the processor 103 of the electronics module 100 from the sensing component 139, a heartrate signal representative of the heartrate of a wearer of the wearable article.

Step S503 comprises determining, by the processor 103 of the electronics module 100 from the heartrate signal, a heartrate value for the heartrate signal. The processor 103 determines a heartrate value by identifying peaks in the heartrate signal representative of heartbeats, using the identified peaks to calculate inter-beat interval (IBI) values representative of the time between successive heartbeats, determining an average IBI value for a time window, and dividing 60000 by the average IBI value in milliseconds. The peaks may be identified according to the process outlined in Figure 8.

Step S504 comprises controlling, by the processor 103 of the electronics module 100, the communicator 109 of the electronics module 100 to transmit a pair of values comprising the heartrate value and a timestamp representative of the time window that the heartrate value relates to. The timestamp occurs after the timestamp for the first valid pair of values.

The communicator 307 of the computing apparatus 300 receives the pair of values from the electronics module.

Step S505 comprises determining, by the processor 305 of the computing apparatus 300, whether the received pair of values satisfy a validity criterion.

If the received pair of values satisfy the validity criterion, the method proceeds to step S506. Step S506 comprises using, by the processor 305 of the computing apparatus 300, the first and second valid pair of values to create at least one intermediate pair of values.

Each of the timestamps for the intermediate pairs of values occurs between the timestamp for the first valid pair of values and the timestamp for the second valid pair of values.

The corrected pairs of values may be displayed to the user as a heartrate trace and may also be used to determine one or more insights for the user.

For example, the controller 305 may use the corrected pairs of values to determine the time the user spends in different training intensity levels. The controller 305 of the user electronics device 300 is operable to determine the maximum heartrate (MHR) for the user using information such as the age and gender of the user. This is stored in memory 304.

In the present example of the invention, the MHR is calculated using an age-based formula such as the following equation:

For female:

190.2

For males:

203.7

where e = Euler’s number = 2.718282

In some examples, the MHR is determined by having the user perform exercise and measure their highest heart rate. The exercise may be maximal effort exercise which is typically performed in a controlled setting although it is also possible to determine MHR during freely performed exercise. Example methods of determining MHR during freely performed exercise are disclosed in European Patent Publication No. EP3656304.

The controller 305 of the user electronics device 300 is also operable to determine which training intensity level the user is currently at using the metrics described above, that is: T raining intensity level 1 : Very light, 50 percent to 60 percent of MHR

T raining intensity level 2: Light, 60 percent to 70 percent of MHR T raining intensity level 3: Moderate, 70 percent to 80 percent of MHR T raining intensity level 4: Hard, 80 percent to 90 percent of MHR Training intensity level 5: Very hard, 90 percent to 100 percent of MHR

The controller 305 may control the user electronic device 300 to display, a ‘Summary’ screen 3040 at the end of a workout session. The Summary screen displays the duration of the workout session 3041 , the maximum heartrate 3042, calories burnt 3043, average heartrate 3044, a heartrate trace 3046 and a summary of the time spent in each of the training intensity levels 3045. This is illustrated in Figure 16. The maximum heartrate 3042, calories burnt 3043, average heartrate 3044, heartrate trace 3046 and the time spent in each of the training intensity levels 3045 may all be derived, at least in part, by the corrected pairs of values generated according to the examples described above.

In summary, there is provided a method and system for correcting heartrate values derived from a heart rate signal. The method is performed by a computing apparatus comprising a processor, a memory and a communicator. The processor obtains, from the memory, a first valid pair of values comprising a heartrate value and a timestamp (S401). The processor receives, from the communicator, a pair of values comprising a heartrate value and a timestamp occurring after the timestamp for the first valid pair of values (S402). The processor determines whether the received pair of values satisfy a validity criterion (S403). If so, the received pair of values are set as a second valid pair of values and used with the first valid pair of values to create an intermediate pair of values (S404). The intermediate pair of values comprises a heartrate value and an intermediate timestamp between the timestamps for the valid pairs of values. The original heartrate value associated with the intermediate timestamp is replaced with a corrected heartrate value that better reflects the heartrate signal.

In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, byway of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables.

Although the example embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1 . A method performed by a computing apparatus for correcting heartrate values derived from a heartrate signal, the computing apparatus comprising a processor, a memory and a communicator, the method comprising: obtaining, by the processor from the memory, a first valid pair of values comprising a heartrate value for the heartrate signal and a timestamp representative of the time window that the heartrate value relates to; receiving, by the processor from the communicator, a pair of values comprising a heartrate value for the heartrate signal and a timestamp representative of the time window that the heartrate value relates to, the timestamp occurring after the timestamp for the first valid pair of values; determining, by the processor, whether the received pair of values satisfy a validity criterion; and if the received pair of values satisfy the validity criterion, the method further comprises: setting, by the processor, the received pair of values as a second valid pair of values; and using, by the processor, the first and second valid pair of values to create at least one intermediate pair of values, wherein each of the intermediate pairs of values comprises a heartrate value and an intermediate timestamp representative of the time window that the heartrate value belongs to, and wherein each of the intermediate timestamps occurs between the timestamp for the first valid pair of values and the timestamp for the second valid pair of values.

2. A method as claimed claim 1 , wherein using the first and second pair of values to create the at least one intermediate pair of values comprises: obtaining, by the processor from the memory, at least one intermediate timestamp that occurs between the timestamp for the first valid pair of values and the timestamp for the second valid pair of values; setting, by the processor, a heartrate value for each of the at least one intermediate timestamp using the first and second pair of values so as to form the at least one intermediate pair of values.

3. A method as claimed in any preceding claim, wherein using the first and second valid pair of values to create at least one intermediate pair of values comprises using the first and second valid pair of values to determine the coefficients of a polynomial function in which time is the independent variable and heartrate is the dependent variable.

4. A method as claimed in claim 3, wherein the polynomial function is a linear function.

5. A method as claimed in claim 3 or 4, wherein using the first and second valid pair of values to create at least one intermediate pair of values further comprises: obtaining, by the processor from the memory, at least one intermediate timestamp that occurs between the timestamps for the first and second valid pair of values; inputting, by the processor, the at least one intermediate timestamp into the polynomial function to obtain a corresponding heartrate value for each of the at least one intermediate timestamps.

6. A method as claimed in any preceding claim, wherein if the received pair of values does not satisfy the validity criterion, the method further comprises: storing, by the processor in the memory, the timestamp for the received pair of values as an intermediate timestamp.

7. A method as claimed in any preceding claim, wherein determining whether the received pair of values satisfy a validity criterion comprises determining the difference between the heartrate value for the received pair of values and the heartrate value for the first valid pair of values.

8. A method as claimed in any preceding claim, wherein determining whether the received pair of values satisfy a validity criterion comprises determining the difference between the timestamp for the received pair of values and the timestamp for the first valid pair of values.

9. A method as claimed in any preceding claim, wherein determining whether the received pair of values satisfy a validity criterion comprises dividing the difference between the heartrate value for the received pair of values and the heartrate value for the first valid pair of values by the difference between the timestamp for the received pair of values and the timestamp for the first valid pair of values.

10. A method as claimed in claim 9, wherein determining whether the received pair of values satisfy a validity criterion comprises comparing the result of dividing the difference between the heartrate value for the received pair of values and the heartrate value for the first valid pair of values by the difference between the timestamp for the received pair of values and the timestamp for the first valid pair of values to a threshold value.

11 . A method as claimed in any preceding claim, wherein determining whether the received pair of values satisfy a validity criterion comprises comparing the heartrate value for the received pair of values to a maximum threshold value.

12. A method as claimed in any preceding claim, wherein determining whether the received pair of values satisfy a validity criterion comprises comparing the heartrate value for the received pair of values to a minimum threshold value.

13. A method as claimed in any preceding claim, further comprising displaying, on a display of the computing apparatus, the first valid pair of values, the at least one intermediate pair of values, and the second valid pair of values.

14. A method performed by a system for correcting heartrate values derived from a heartrate signal, the system comprising an electronics module for a wearable article, the electronics module comprising a processor, a memory, a communicator and a sensing component, and a computing apparatus comprising a processor, a memory and a communicator, the method comprising: obtaining, by the processor of the computing apparatus from the memory of the computing apparatus, a first valid pair of values comprising a heartrate value for the heartrate signal and a timestamp representative of the time window that the heartrate value relates to; receiving, by the processor of the electronics module from the sensing component, a heartrate signal representative of the heartrate of a wearer of the wearable article; determining, by the processor of the electronics module from the heartrate signal, a heartrate value for the heartrate signal; controlling, by the processor of the electronics module, the communicator of the electronics module to transmit a pair of values comprising the heartrate value and a timestamp representative of the time window that the heartrate value relates to, the timestamp occurring after the timestamp for the first valid pair of values; receiving, by the communicator of the computing apparatus, the pair of values from the electronics module; determining, by the processor of the computing apparatus, whether the received pair of values satisfy a validity criterion; and if the received pair of values satisfy the validity criterion, the method further comprises: setting, by the processor of the computing apparatus, the received pair of values as a second valid pair of values using, by the processor of the computing apparatus, the first and second valid pair of values to create at least one intermediate pair of values, wherein each of the intermediate pairs of values comprises a heartrate value and an intermediate timestamp representative of the time window that the heartrate value belongs to, and wherein each of the intermediate timestamps occurs between the timestamp for the first valid pair of values and the timestamp for the second valid pair of values.

15. A computing apparatus comprising a processor, a memory and a communicator, the memory storing instructions which, when executed by the processor, cause the processor to perform operations comprising: obtaining, from the memory, a first valid pair of values comprising a heartrate value derived from a heartrate signal and a timestamp representative of the time window that the heartrate value relates to; receiving, from the communicator, a pair of values comprising a heartrate value derived from the heartrate signal and a timestamp representative of the time window that the heartrate value relates to, the timestamp occurring after the timestamp for the first valid pair of values; determining whether the received pair of values satisfy a validity criterion; and if the received pair of values satisfy the validity criterion, the operations further comprises: setting the received pair of values as a second valid pair of values; and using the first and second valid pair of values to create at least one intermediate pair of values, wherein each of the intermediate pairs of values comprises a heartrate value and a timestamp representative of the time window that the heartrate value belongs to, and wherein each of the intermediate timestamps occurs between the timestamp for the first valid pair of values and the timestamp for the second valid pair of values.

16. A system comprising: an electronics module for a wearable article, the electronics module comprising a processor, a memory, a communicator and a sensing component; and a computing apparatus comprising a processor, a memory and a communicator; the processor of the computing apparatus is operable to obtain, from the memory of the computing apparatus, a first valid pair of values comprising a heartrate value representative of a heartrate signal and a timestamp representative of the time window that the first heartrate value relates to; the processor of the electronics module is operable to receive, from the sensing component, a heartrate signal representative of the heartrate of a wearer of the wearable article; the processor of the electronics module is operable to determine, from the heartrate signal, a heartrate value for the heartrate signal; the processor of the electronics module is operable to control the communicator to transmit a pair of values comprising the heartrate value and a timestamp representative of the time window that the heartrate value relates to, the timestamp occurring after the timestamp for the first valid pair of values; the communicator of the computing apparatus is operable to receive the pair of values from the electronics module; the processor of the computing apparatus is operable to determine whether the received pair of values satisfy a validity criterion; and if the received pair of values satisfy the validity criterion, the processor of the computing apparatus is operable to set the received pair of values as a second valid pair of values and use the first and second valid pair of values to create at least one intermediate pair of values, wherein each of the intermediate pairs of values comprises a heartrate value and a timestamp representative of the time window that the heartrate value belongs to, and wherein each of the intermediate timestamps occurs between the timestamp for the first valid pair of values and the timestamp for the second valid pair of values.