KR102303601B1 - Method and apparatus for removing motion artifact of vital sign signal - Google Patents

Abstract

A method and apparatus for removing motion noise of a vital sine signal are disclosed. A method for removing motion noise according to an embodiment includes receiving a first vital sign signal that is a single channel signal, and a plurality of second multiple channel signals from the first vital sign signal based on a time delay. generating vital sine signals; and generating a third vital sine signal in which a motion artifact signal is removed from the first vital sine signal based on the plurality of second vital sine signals.

Description

Method and apparatus for removing motion noise of vital sine signals

The following embodiments relate to a method and apparatus for removing motion noise of a vital sine signal.

A vital sign signal represents a person's vital signs, such as breathing, body temperature, and heartbeat. The vital sign signal is the most important and essential signal to be measured in medical practice. The vital sign signal may be used as an important indicator in the field of fitness and wellness applied thereto as well as in medical practice.

The vital sign signal is acquired during the user's daily life by attaching a vital sign measuring device to the user's body. In this case, in order to obtain a high quality vital sign signal, it is necessary to remove motion artifacts generated by the user's breathing or movement. Motion noise is a signal distortion caused by the movement of electrodes. Dynamic noise is generated because the electric charge distribution is disturbed at the electrode-electrolyte interface due to the movement of the electrode, which causes a change in the half-cell potential and causes a change in the biopotential to be measured.

As an existing algorithm for removing the motion noise included in the vital sine signal, the BSS (Blind Source Separation) algorithm that separates a plurality of vital sine signals obtained from a multi-channel signal and the motion noise included therein, and the user and vital An adaptive filter algorithm that removes motion noise by additionally measuring additional information such as impedance between electrodes measuring a sine signal is mainly used.

Therefore, when the motion noise is removed using an existing algorithm, a vital sine signal must be obtained using multiple channels or other signals related to the motion noise must be additionally measured, so a signal must be obtained with a plurality of electrodes. However, unlike a vital sign measuring device used in hospitals, it is difficult to use a plurality of electrodes in a wearable smart device for continuous signal measurement. In addition, in order to minimize the motion noise, there is a great inconvenience in using that the user must maintain a static posture during signal measurement.
As a related prior art, there is Korean Patent Application Laid-Open No. 10-2017-0133668.

Embodiments may provide a technology capable of removing motion noise included in a vital sine signal, which is a single channel signal, by dramatically reducing the amount of computation.

A method for removing motion noise according to an embodiment includes receiving a first vital sign signal that is a single channel signal, and a plurality of second multiple channel signals from the first vital sign signal based on a time delay. generating vital sine signals; and generating a third vital sine signal in which a motion artifact signal is removed from the first vital sine signal based on the plurality of second vital sine signals.

The generating of the plurality of second vital sign signals may include generating the plurality of second vital sign signals by delaying the first vital sign signal by a channel delay time.

The generating of the plurality of second vital sign signals by delaying the first vital sign signal by a channel delay time may include delaying the first vital sign signal by an integer multiple of the channel delay time to thereby delay the plurality of second vital signs. generating signals.

The generating of the third vital sine signal may include extracting the motion noise using the plurality of second vital sine signals, and the third vital sine signal based on the motion noise and the first vital sine signal. generating a signal.

The extracting may include extracting the average power of the plurality of second vital sign signals calculated using the plurality of second vital sign signals as the motion noise.

The extracting may include extracting a correlation value between the plurality of second vital sign signals as the motion noise.

The generating of the third vital sine signal based on the motion noise and the first vital sine signal includes: performing low-pass filtering on the motion noise, and calculating an offset of the low-pass filtered motion noise. It may include removing the offset and generating the third vital sine signal based on the first vital sine signal and the motion noise from which the offset has been removed.

An apparatus for removing motion noise according to an embodiment includes a memory storing instructions for removing motion noise, and a processor for executing the instructions, wherein when the instructions are executed by the processor, the processor is configured to: Receive a first vital sign signal that is a signal, and generate the first vital sign signal as a plurality of second vital sign signals that are multi-channel signals based on a time delay, and the plurality of second vital signs A third vital sine signal obtained by removing a motion artifact signal from the first vital sine signal is generated based on the signals.

The processor may generate the plurality of second vital sign signals by delaying the first vital sign signal by a channel delay time.

The plurality of second vital sign signals may be generated by delaying the first vital sign signal by an integer multiple of the channel delay time.

The processor may extract the motion noise using the plurality of second vital sine signals, and generate the third vital sine signal based on the motion noise and the first vital sine signal.

The processor may extract an average power of the plurality of second vital sign signals calculated using the plurality of second vital sign signals as the motion noise.

The processor may extract a correlation value between the plurality of second vital sign signals as the motion noise.

The processor performs low-pass filtering on the motion noise, removes an offset of the low-pass-filtered motion noise, and the third vital signal is based on the offset-removed motion noise and the first vital sine signal. A sine signal can be generated.

1 is a diagram illustrating a system for removing motion noise according to an embodiment.
FIG. 2 is a diagram schematically illustrating the apparatus for removing motion noise shown in FIG. 1 .
FIG. 3 is a diagram schematically illustrating the processor shown in FIG. 2 .
4 to 7 are diagrams illustrating examples of signals for explaining an operation of a processor.
8 is a flowchart for explaining the operation of the motion noise removing apparatus.
9 and 10 are diagrams for comparing the performance of the motion noise canceling apparatus and the conventional BSS algorithm.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, since various changes may be made to the embodiments, the scope of the patent application is not limited or limited by these embodiments. It should be understood that all modifications, equivalents and substitutes for the embodiments are included in the scope of the rights.

The terms used in the examples are used for description purposes only, and should not be construed as limiting. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Although terms such as first or second may be used to describe various elements, the elements should not be limited by the terms. The terms are only for the purpose of distinguishing one element from another element, for example, without departing from the scope of rights according to the concept of the embodiment, a first element may be named as a second element, and similarly The second component may also be referred to as the first component.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiment belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

In addition, in the description with reference to the accompanying drawings, the same components are given the same reference numerals regardless of the reference numerals, and the overlapping description thereof will be omitted. In the description of the embodiment, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted.

A module in the present specification may mean hardware capable of performing functions and operations according to each name described in this specification, or may mean computer program code capable of performing specific functions and operations, , or an electronic recording medium on which a computer program code capable of performing a specific function and operation is loaded, for example, a processor or a microprocessor.

In other words, a module may mean a functional and/or structural combination of hardware for carrying out the technical idea of the present invention and/or software for driving the hardware.

1 is a diagram illustrating a system for removing motion noise according to an embodiment.

The motion noise removal system 10 includes a vital sign measuring device 100 and a motion noise removal device 300 .

The motion-noise removal system 10 extends a single-channel signal to a multi-channel signal based on a time delay, and may optimize the motion artifact removal performance by varying the number of channels and the number of time-delayed samples.

The motion noise removal system 10 is effective even through a single channel without using a plurality of electrodes and/or a plurality of channels, without using a plurality of electrodes and/or a plurality of channels to remove the motion noise that may be generated from the user's breathing or movement when measuring a vital sign signal. can be removed

For example, the motion noise cancellation system 10 may be implemented in a wearable smart device and/or an electronic device. The motion noise removal system 10 improves the usability of a wearable smart device and/or an electronic device for measuring an electrocardiogram and/or oxygen saturation, etc., thereby effectively detecting a vital sign signal even when a user moves during the vital sign signal measurement. .

The vital sign measuring apparatus 100 may be attached to the user's body to generate a first vital sign signal that is a vital sign of the user. For example, the vital sine measuring apparatus 100 may acquire the first vital sine signal through a single channel. The vital sign measuring apparatus 100 may be attached to the user's body through a single electrode to obtain a first vital sign signal. The first vital sign signal may include motion noise.

The vital sine measuring apparatus 100 may transmit a first vital sine signal to the motion noise removing apparatus 300 .

The apparatus 300 for removing motion noise may generate a vital sine signal from which motion noise is removed based on a vital sine signal acquired through a single channel. The apparatus 300 for removing motion noise can remove motion noise included in the vital sine signal by remarkably reducing the amount of computation.

The motion noise removing apparatus 300 may check the user's health status in various ways by using the vital sign signal from which the motion noise is removed.

The apparatus 300 for removing motion noise may generate a plurality of second vital sine signals that are multi-channel signals from the first vital sine signal based on the time delay. The apparatus 300 for removing motion noise may generate a third vital sine signal obtained by removing the motion noise signal from the first vital sine signal based on the plurality of second vital sine signals.

2 is a diagram schematically showing the motion noise removing apparatus shown in FIG. 1, FIG. 3 is a diagram schematically showing the processor shown in FIG. 2, and FIGS. 4 to 7 are signals for explaining the operation of the processor. It is a drawing showing an example.

The motion noise cancellation apparatus 300 may include a transceiver 310 , a processor 330 , and a memory 350 .

The transceiver 310 may receive the first vital sign signal. The first vital sign signal 410 may include a motion noise 450 . The transceiver 310 may output the first vital sign signal 410 to the processor 330 .

The transceiver 310 may transmit a third vital sign signal 710 .

The processor 330 may include one or more of a central processing unit, an application processor, and a communication processor.

The processor 330 may execute an operation or data processing related to control of at least one other component of the motion noise removing apparatus 300 . For example, the processor 330 may execute an application and/or software stored in the memory 350 .

The processor 330 may process data received by the transceiver 310 and data stored in the memory 350 . The processor 330 may process data stored in the memory 350 . The processor 330 may execute computer readable code (eg, software) stored in the memory 350 and instructions induced by the processor 330 .

The processor 330 may be a hardware-implemented data processing device having a circuit having a physical structure for executing desired operations. For example, desired operations may include code or instructions included in a program.

For example, a data processing device implemented as hardware includes a microprocessor, a central processing unit, a processor core, a multi-core processor, and a multiprocessor. , an Application-Specific Integrated Circuit (ASIC), and a Field Programmable Gate Array (FPGA).

The processor 330 may generate a plurality of second vital sign signals 510 that are multi-channel signals from the first vital sign signal 410 based on the time delay t.

The processor 330 may generate a third vital sine signal 710 in which the motion noise 450 is removed from the first vital sine signal 410 based on the plurality of second vital sine signals 510 .

The processor 330 may include a channel expander 331 and a motion noise canceller 335 .

The channel expander 331 may generate a plurality of second vital sign signals 510 by delaying the first vital sign signal 410 by a channel delay time t. For example, the channel expander 331 may generate a plurality of second vital sign signals 510 by delaying the first vital sign signal 410 by an integer multiple of the channel delay time t. In this case, the integer may have a range from 1 (or 0) to (number of channels - 1).

The channel expander 331 may output the plurality of second vital sine signals 510 to the motion noise canceller 335 .

The dynamic noise canceller 335 may generate the third vital sine signal 710 by removing the dynamic noise 450 from the first vital sine signal 410 .

Referring to FIG. 6 , the motion noise remover 335 may extract the motion noise 450 using the plurality of second vital sine signals 510 . Referring to FIG. 7 , the motion noise canceller 335 may generate a third vital sine signal 710 based on the motion noise 450 and the first vital sine signal 410 .

The motion noise canceller 335 may include a motion noise extraction module 335-1, a low-pass filter 335-3, an offset removal module 335-5, and an adaptive filter 335-7.

The dynamic noise extraction module 335 - 1 may extract the average power of the plurality of second vital sine signals 510 calculated using the plurality of second vital sine signals 510 as the dynamic noise 450 . have. The motion noise extraction module 335 - 1 may calculate the average power through Equation (1).

는 평균 전력,

는 복수의 제2 바이탈 사인 신호들,

은 채널수,

는 채널 지연을 의미할 수 있다.

is the average power,

is a plurality of second vital sign signals,

is the number of channels,

may mean a channel delay.

As another example, the motion noise extraction module 335 - 1 may extract a correlation value between the plurality of second vital sine signals 510 as the motion noise 450 . The motion noise extraction module 335-1 may calculate a correlation value through Equation (2).

는 평균 전력,

는 복수의 제2 바이탈 사인 신호들,

은 채널수,

는 채널 지연을 의미할 수 있다.

is the average power,

is a plurality of second vital sign signals,

is the number of channels,

may mean a channel delay.

As another example, the motion noise extraction module 335 - 1 performs a Principal Component Analysis (PCA) algorithm or an Independent Component Analysis (ICA) algorithm on the plurality of second vital sine signals 510 to obtain the motion noise 450 . ) can be extracted.

That is, the motion noise signal is close to the baseline shaking, and the first vital sine signal, which changes faster than the baseline, appears only at one point in the plurality of second vital sine signals, which are delayed signals, so that an average or correlation is taken. If the magnitude of the first vital sine signal after the operation is relatively weak, the magnitude may be weakened. However, since the baseline appears in common among a plurality of second vital sine signals, which are delayed signals, its shape may be maintained after an average or correlation operation. Accordingly, the motion noise extraction module 335-1 may extract the motion noise through a simple operation without taking a matrix operation requiring a large amount of computation like the existing BBS algorithm.

The dynamic noise extraction module 335 - 1 may output the dynamic noise 450 to the low pass filter 335 - 3 .

The low-pass filter 335 - 3 may perform low-pass filtering on the motion noise. The low-pass filter 335 - 3 may output the low-pass filtered dynamic noise to the offset removal module 335 - 5 .

The offset removal module 335 - 5 may remove an offset of the low-pass filtered motion noise. The offset removal module 335 - 5 may output the motion noise from which the offset has been removed to the adaptive filter 335 - 7 .

The adaptive filter 335 - 7 may generate a third vital sine signal based on the offset-removed motion noise and the first vital sine signal. For example, the adaptive filter 335-7 receives a third vital sine signal from which the dynamic noise 450 is removed from the first vital sine signal 410 by using the offset-removed dynamic noise and the first vital sine signal. can create

Memory 350 may include volatile and/or non-volatile memory. The memory 350 may store commands and/or data related to at least one other component of the motion noise cancellation apparatus 300 .

The memory 350 may store software and/or a program. For example, the memory 350 may store applications and software for removing motion noise.

8 is a flowchart for explaining the operation of the apparatus for removing motion noise, and FIGS. 9 and 10 are diagrams for comparing the performance of the apparatus for removing motion noise and the existing BSS algorithm.

The motion noise removing apparatus 300 may receive a first vital sign signal that is a single channel signal ( 810 ).

The apparatus 300 for removing motion noise may generate a plurality of second vital sine signals that are multi-channel signals from the first vital sine signal based on the time delay ( 820 ).

The apparatus 300 for removing motion noise may generate a third vital sine signal obtained by removing the motion noise signal from the first vital sine signal based on the plurality of second vital sine signals ( 830 ).

9 and 10 , the vital sine signal used in the performance experiment may be an electrocardiogram signal that can be measured through an electrode. As can be seen from the performance experiments of FIGS. 9 and 10 , the output signals 930 and 1030 from which the motion noise removal device 300 removes the motion noise signal according to the input signals 910 and 1010, and the existing BSS algorithm are input It can be seen that the output signals 950 and 1050 obtained by removing the motion noise signal according to the signals 910 and 1010 exhibit similar effects.

That is, the existing BSS algorithm finds the basis vector constituting the multi-channel signal through the multi-channel signal, and uses the fact that there is little correlation between the basis vectors to reduce the motion noise included in the vital sine signal and the vital sine signal. can be separated. However, since the existing BSS algorithm needs to extract a basis vector of a multi-channel signal for the separation of motion noise, a matrix operation is required.

However, since the motion noise removal apparatus 300 can remove the motion noise from the vital sign signal through significantly fewer calculations than the conventional BSS algorithm, it may be more advantageous in terms of operation speed and resource consumption than the conventional BSS algorithm.

The motion noise removal system 10 can measure a reliable vital sign signal even when a user moves a lot in a wearable smart device that is recently used a lot. Therefore, the motion noise removal system 10 can greatly improve the popular dissemination of wearable smart devices by enhancing user convenience. For example, the motion noise removal system 10 may be applied to a wearable smart device for measuring an electrocardiogram, a smart watch, a smart phone, and the like.

The motion noise removal system 10 is less affected by the user's movement and external interference through the removal of the motion noise included in the vital sign signal, so that the signal measurement during the user's movement is important during exercise, health care and/or driving It can be expanded to various application fields for driver's condition detection and the like.

Since the motion noise removal system 10 can collect bio-signals even in the presence of a user's movement, it can be applied to a health management system during exercise, a driver's condition monitoring system, and the like. That is, if the motion noise removal system 10 is implemented in a wearable smart device and/or an IoT device that is vulnerable to an existing movement, its usability can be greatly increased.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and available to those skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic such as floppy disks. - includes magneto-optical media, and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

The software may comprise a computer program, code, instructions, or a combination of one or more thereof, which configures a processing device to operate as desired or is independently or collectively processed You can command the device. The software and/or data may be any kind of machine, component, physical device, virtual equipment, computer storage medium or device, to be interpreted by or to provide instructions or data to the processing device. , or may be permanently or temporarily embody in a transmitted signal wave. The software may be distributed over networked computer systems, and stored or executed in a distributed manner. Software and data may be stored in one or more computer-readable recording media.

As described above, although the embodiments have been described with reference to the limited drawings, those skilled in the art may apply various technical modifications and variations based on the above. For example, the described techniques are performed in a different order than the described method, and/or the described components of the system, structure, apparatus, circuit, etc. are combined or combined in a different form than the described method, or other components Or substituted or substituted by equivalents may achieve an appropriate result.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (14)

A method for removing motion noise of a motion noise removing device, the method comprising:
receiving, by the motion noise cancellation device, a first vital sign signal, which is a single channel signal, from a vital sign measuring device;
generating a plurality of second vital sine signals that are multi-channel signals by delaying the first vital sine signal by a channel delay time by the motion noise canceling device;
extracting, by the apparatus for removing motion noise, an average power or correlation value of the plurality of second vital sine signals as a motion artifact signal; and
generating, by the apparatus for removing the motion noise, a third vital sine signal by removing the motion noise signal from the first vital sine signal
A method of removing motion noise, including
delete According to claim 1,
The generating of the plurality of second vital sign signals comprises:
generating the plurality of second vital sign signals by delaying the first vital sign signal by an integer multiple of the channel delay time;
A method for removing motion noise, including
delete According to claim 1,
The extraction step is
extracting the average power of the plurality of second vital sign signals calculated using the plurality of second vital sign signals as the motion noise;
A method for removing motion noise, including
According to claim 1,
The extraction step is
extracting a correlation value between the plurality of second vital sine signals as the motion noise
A method for removing motion noise, including
According to claim 1,
The step of generating the third vital sign signal comprises:
performing low-pass filtering on the motion noise;
removing an offset of the low-pass filtered motion noise; and
generating the third vital sine signal based on the offset-removed motion noise and the first vital sine signal
A method for removing motion noise, including
a memory for storing instructions for removing motion noise; and
a processor for executing the instructions
including,
When the instructions are executed by the processor, the processor
Receiving a first vital sign signal (vital sign) that is a single channel signal from the vital sign measurement device,
by delaying the first vital sine signal by a channel delay time to generate a plurality of second vital sine signals that are multi-channel signals,
extracting the average power or correlation value of the plurality of second vital sine signals as a motion artifact signal;
generating a third vital sine signal by removing the motion noise signal from the first vital sine signal
Motion noise canceling device.
delete 9. The method of claim 8,
generating the plurality of second vital sign signals by delaying the first vital sign signal by an integer multiple of the channel delay time
Motion noise canceling device.
delete 9. The method of claim 8,
The processor is
extracting the average power of the plurality of second vital sine signals calculated using the plurality of second vital sine signals as the motion noise
Motion noise canceling device.
9. The method of claim 8,
The processor is
extracting a correlation value between the plurality of second vital sine signals as the motion noise
Motion noise canceling device.
9. The method of claim 8,
The processor is
performing low-pass filtering on the motion noise;
Remove the offset of the low-pass filtered motion noise,
generating the third vital sine signal based on the first vital sine signal and the motion noise from which the offset has been removed
Motion noise canceling device.

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