CN112494001A - PPG signal quality evaluation method and device, wearable device and storage medium - Google Patents
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Abstract
The invention discloses a PPG signal quality evaluation method, a device, wearable equipment and a storage medium, which are used for evaluating whether a PPG signal acquired by the wearable equipment can be analyzed, wherein the wearable equipment is provided with an acceleration sensor, and the PPG signal quality evaluation method comprises the following steps: acquiring a PPG signal acquired by wearable equipment and an acceleration signal output by an acceleration sensor; carrying out time domain to frequency domain conversion on the acquired PPG signal and the acceleration signal to obtain the PPG signal and the acceleration signal in a frequency domain; and comparing the amplitude spectrum of the PPG signal in the frequency domain with the amplitude spectrum of the acceleration signal to obtain a quality evaluation result of the PPG signal. According to the invention, the quality of the PPG signal is obtained through the signal characteristics in the frequency domain, and the problem that the signal quality cannot be analyzed due to the fact that the PPG signal is not obvious in the motion state of the existing wearable equipment is further improved.
Description
Technical Field
The invention relates to the field of digital signal processing, in particular to a PPG signal quality evaluation method, a PPG signal quality evaluation device, wearable equipment and a storage medium.
Background
The photoplethysmography (PPG) is a non-invasive detection method for detecting blood volume change in living tissues by means of photoelectricity, can be used for estimating blood oxygen saturation (SPO2), heart rate, blood pressure and the like, and PPG measuring equipment is small in size, convenient to carry and wide in application, but the PPG signal has interference of motion artifacts, and the PPG signal with serious interference can mislead or make the detection algorithms of blood oxygen \ heart rate \ blood pressure and the like incapable of running, so that the quality of the PPG signal is a precondition for ensuring effective detection of the algorithms of blood oxygen \ heart rate \ blood pressure and the like.
The existing PPG signal quality detection method analyzes the signal quality through the PPG signal characteristics over a time period, but the characteristics of the PPG signal are not obvious in a motion state, and the signal quality cannot be evaluated in the motion state.
Disclosure of Invention
The invention mainly aims to provide a PPG signal quality evaluation method, a PPG signal quality evaluation device, wearable equipment and a storage medium, and aims to solve the problem that the existing PPG signal cannot be subjected to signal quality evaluation under the condition of movement.
In order to achieve the above object, the present invention provides a PPG signal quality evaluation method for evaluating whether a PPG signal acquired by a wearable device can be analyzed, the wearable device has an acceleration sensor, and the PPG signal quality evaluation method includes the following steps:
acquiring a PPG signal acquired by wearable equipment and an acceleration signal output by an acceleration sensor;
carrying out time domain to frequency domain conversion on the acquired PPG signal and the acceleration signal to obtain the PPG signal and the acceleration signal in a frequency domain; and
and comparing the amplitude spectrum of the PPG signal in the frequency domain with the amplitude spectrum of the acceleration signal to obtain a quality evaluation result of the PPG signal.
Optionally, the comparing the amplitude spectrum of the PPG signal in the frequency domain with the amplitude spectrum of the acceleration signal, and obtaining the quality evaluation result of the PPG signal includes:
and when the coincidence degree of the amplitude spectrum of the PPG signal and the amplitude spectrum of the acceleration signal in the frequency domain reaches a preset coincidence degree range, determining that the quality evaluation result of the PPG signal is that the PPG signal cannot be analyzed.
Optionally, the comparing the amplitude spectrum of the PPG signal in the frequency domain with the amplitude spectrum of the acceleration signal to obtain the quality evaluation result of the PPG signal further includes:
when the magnitude spectrum of the PPG signal and the magnitude spectrum of the acceleration signal in the frequency domain do not reach a preset goodness of fit range, calculating a deviation value of the magnitude spectrum of the PPG signal and the magnitude spectrum of the acceleration signal in the frequency domain; and
and comparing the deviation value with a preset maximum deviation value, and determining that the quality evaluation result of the PPG signal is that the PPG signal cannot be analyzed when the deviation value is smaller than or equal to the preset maximum deviation value.
Optionally, the comparing the amplitude spectrum of the PPG signal in the frequency domain with the amplitude spectrum of the acceleration signal to obtain the evaluation result of the PPG signal quality further includes:
when the deviation value is larger than the preset maximum deviation value, subtracting the frequency domain signal of the acceleration signal from the frequency domain signal of the PPG signal to obtain a synthesized frequency domain signal; and
and acquiring the number of spectral peaks of the synthesized frequency domain signal in a preset spectral range, and determining the quality evaluation result of the PPG signal based on the number of spectral peaks.
Optionally, the determining a quality assessment result of the PPG signal based on the number of spectral peaks comprises:
the number of spectral peaks is inversely related to the PPG signal quality.
Optionally, the determining a quality assessment result of the PPG signal based on the number of spectral peaks comprises:
and when the number of the spectrum peaks is less than or equal to the preset minimum number of the spectrum peaks, determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed.
Optionally, when the number of spectral peaks is greater than a preset minimum number of spectral peaks, the determining a quality evaluation result of the PPG signal based on the number of spectral peaks further includes:
determining the maximum spectral amplitude in the synthesized frequency domain signal, comparing a frequency value corresponding to the maximum spectral amplitude with a preset frequency interval, and determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed when the frequency value corresponding to the maximum spectral amplitude is in the preset frequency interval; and/or
Determining a second large frequency spectrum amplitude in the synthesized frequency domain signal, comparing a frequency value corresponding to the second large frequency spectrum amplitude with a preset frequency interval, and determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed when the frequency value corresponding to the second large frequency spectrum amplitude is in the preset frequency interval; and/or
Determining a third large frequency spectrum amplitude in the synthesized frequency domain signal, comparing a frequency value corresponding to the third large frequency spectrum amplitude with a preset frequency interval, and determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed when the frequency value corresponding to the third large frequency spectrum amplitude is in the preset frequency interval;
the preset frequency interval is not greater than the maximum frequency value of the synthesized frequency domain signal and not less than the minimum frequency value of the synthesized frequency domain signal.
Optionally, when the number of spectral peaks is greater than a preset minimum number of spectral peaks, the determining a quality evaluation result of the PPG signal based on the number of spectral peaks further includes:
determining the maximum spectral amplitude, the second large spectral amplitude and the third large spectral amplitude in the synthesized frequency domain signal, wherein the quality of the PPG signal decreases under frequency values respectively corresponding to the maximum spectral amplitude, the second large spectral amplitude and the third large spectral amplitude.
Optionally, after the step of acquiring the PPG signal acquired by the wearable device and the acceleration signal output by the acceleration sensor, the PPG signal quality assessment method further includes:
and carrying out band-pass filtering and denoising on the acquired PPG signal and the acceleration signal to obtain the PPG signal and the acceleration signal in a time domain.
The invention also proposes a PPG signal quality evaluation device implementing the method as described above, said device comprising:
the signal generating unit is used for outputting a PPG signal and an acceleration signal;
a processor; and
a memory for storing the PPG signal quality assessment program executable on the processor; the PPG signal quality evaluation procedure, when executed by the processor, implements the steps of the PPG signal quality evaluation method as claimed above.
The invention also provides a wearable device, which stores the device for executing the PPG signal quality evaluation method.
The invention also proposes a storage medium storing an evaluation program of a PPG signal quality device which, when executed by a processor, implements the steps of the PPG signal quality evaluation method as described above.
According to the technical scheme, the PPG signal and the acceleration signal output by the acceleration sensor are collected, the PPG signal and the acceleration signal in a time domain are converted into frequency domain signals, comparison is carried out according to the magnitude spectrum of the PPG signal in a comparison frequency domain and the magnitude spectrum of the acceleration signal in the frequency domain, the quality of the PPG signal is obtained through the signal characteristics in the frequency domain, and the problem that the signal quality cannot be analyzed due to the fact that the PPG signal is not obvious in the motion state of existing wearable equipment is solved.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a schematic flowchart of a PPG signal evaluation method according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of another embodiment of the PPG signal evaluation method of the present invention;
fig. 3 is a schematic flow chart of a PPG signal evaluation method according to another embodiment of the present invention;
fig. 4 is a schematic diagram of a hardware structure of an embodiment of the PPG signal evaluation device of the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a PPG signal quality evaluation method which is used for evaluating whether a PPG signal acquired by wearable equipment in a motion state can be analyzed or not, wherein the wearable equipment is provided with an acceleration sensor, and the acceleration sensor is used for acquiring an acceleration signal of the wearable equipment in the motion state. The wearable device detects blood volume changes in living tissue by photoplethysmography (PPG), which may characterize parameters such as heart rate signals. The quality of the PPG signal corresponds to the analytic performance of the PPG signal, and the analytic performance of the PPG signal is better along with the increase of the quality of the PPG signal.
Referring to fig. 1, in the present embodiment, the PPG signal quality evaluation method includes the following steps:
s100: and acquiring a PPG signal acquired by the wearable device and an acceleration signal output by the acceleration sensor.
The PPG signal and the acceleration signal output by the acceleration sensor are both time domain signals. Wherein the PPG signal and the acceleration signal are both signals acquired in the same time period. Through synchronous acquisition the acceleration signal can conveniently introduce the acceleration characteristic of the motion state of wearable equipment into the evaluation of PPG signal quality.
S200: and carrying out time domain to frequency domain conversion on the acquired PPG signal and the acceleration signal to obtain the PPG signal and the acceleration signal in the frequency domain.
After the PPG signal and the acceleration signal in the same time period are obtained, Fourier transform is carried out on the PPG signal and the acceleration signal in the time domain to obtain the PPG signal and the acceleration signal in the frequency domain, so that the PPG signal and the acceleration signal in the frequency domain can be conveniently analyzed.
S300: and comparing the amplitude spectrum of the PPG signal in the frequency domain with the amplitude spectrum of the acceleration signal to obtain a quality evaluation result of the PPG signal.
In an embodiment, the detection time periods may be defined as the PPG signal and the acceleration signal of 1 to 5 seconds, the PPG signal and the acceleration signal of 1 to 10 seconds, and the PPG signal and the acceleration signal of 1 to 15 seconds in the motion state, so as to perform detection evaluation respectively.
Since the PPG signal quality characterizes the analytical performance of the PPG signal, when the PPG signal is analyzed, it can be analyzed when the PPG signal quality reaches a certain range. Taking the optimal value of the PPG signal quality as 100 as an example, when the PPG signal quality reaches or approaches the optimal value of 100, the PPG signal is resolvable; when the PPG signal quality is higher than a preset signal quality value and lower than an optimal value of 100, the PPG signal quality is lower than the optimal value, but the PPG signal can be analyzed; and when the PPG signal is lower than the preset signal quality value, the quality of the PPG signal is lower, and the PPG signal cannot meet the analysis requirement, determining that the PPG signal cannot be analyzed. Generally, when the optimal value of the PPG signal quality is 100 and the PPG signal quality is higher than 50, the PPG signal can be analyzed, and as the PPG signal quality improves, the analysis performance of the PPG signal also gradually improves, i.e., the PPG signal quality is positively correlated with the analysis performance of the PPG signal.
In this embodiment, by introducing the acceleration signal of the acceleration sensor, the signal characteristics of the PPG signal in the frequency domain are compared with the signal characteristics of the acceleration signal in the frequency domain, so that the interference of motion artifacts in the motion state is eliminated, and the reliability of signal quality detection and evaluation is improved. Because signal characteristics under the frequency domain are adopted for comparison, the obtained signal characteristics are more obvious, clear comparison and analysis can be carried out, the efficiency of PPG signal analysis is improved, the clear analysis result is carried out on the PPG signal characteristics, and the feasibility of PPG signal analysis is improved.
In an embodiment, in order to reduce interference of inherent noise of the PPG signal, optionally, after the step of acquiring the PPG signal acquired by the wearable device and the acceleration signal output by the acceleration sensor, the acquired PPG signal and the acceleration signal are subjected to band-pass filtering and denoising, the PPG signal is subjected to low-pass filtering, processable high-frequency noise is filtered, then high-pass filtering is performed, processable baseline drift and low-frequency noise are filtered, the PPG signal and the acceleration signal in a time domain are obtained, and then fourier transformation is performed on the PPG signal and the acceleration signal in the time domain, so as to avoid interference of the evaluation result by the inherent noise in the PPG signal.
In an embodiment, in step S300, when the goodness of fit of the magnitude spectrum of the PPG signal and the magnitude spectrum of the acceleration signal in the frequency domain reaches a preset goodness of fit range, it is determined that the interference of the motion artifact on the PPG signal is serious, and the interference of the motion artifact cannot be removed from the PPG signal, and at this time, it is determined that the quality evaluation result of the PPG signal is that the PPG signal cannot be analyzed.
The PPG signal quality has an optimal value SQ, and the preset goodness of fit range is close to the optimal value SQ, for example, within a 10% SQ range, all within the preset goodness of fit range. When the method is used for different devices, a certain deviation exists in a preset goodness-of-fit range, generally, taking a smart watch as an example, the optimal value SQ of the PPG signal is preset to 100, and when the amplitude spectrum of the PPG signal in the frequency domain is consistent with the amplitude spectrum of the acceleration signal, the frequency spectrum of the PPG signal may alias the motion spectrum, so that the quality of the PPG signal is 10, the quality of the signal is the worst, and the analysis performance of the PPG signal is the worst.
And when determining whether the amplitude spectrum of the PPG signal in the frequency domain is inconsistent or not and the amplitude spectrum of the acceleration signal is basically inconsistent, the obtained PPG signal is less interfered by motion artifacts, and determining whether the quality of the obtained PPG signal is in an optimal value so as to determine whether the obtained PPG signal can be analyzed and further obtain the quality of the current PPG signal intuitively.
Referring to fig. 2, in another embodiment, when the currently obtained PPG signal is interfered by motion artifacts, the matching degree of the amplitude spectrum of the frequency domain PPG signal and the amplitude spectrum of the acceleration signal may not reach a preset matching degree range, and the step S300 includes:
s310: and when the goodness of fit of the magnitude spectrum of the PPG signal and the magnitude spectrum of the acceleration signal in the frequency domain does not reach a preset goodness of fit range, calculating a deviation value of the magnitude spectrum of the PPG signal and the magnitude spectrum of the acceleration signal in the frequency domain.
And when the amplitude spectrum of the PPG signal in the frequency domain is inconsistent with the amplitude spectrum of the acceleration signal and the phase difference range exceeds a preset goodness-of-fit range, the interference of the motion artifact on the PPG signal obtained currently is indicated. Taking the smart watch as an example, when the PPG signal quality is SQ < 90, calculating a deviation value between the amplitude spectrum of the PPG signal and the amplitude spectrum of the acceleration signal in the contrast frequency domain.
S311: and comparing the deviation value with a preset maximum deviation value, and determining that the quality evaluation result of the PPG signal is that the PPG signal cannot be analyzed when the deviation value is smaller than or equal to the preset maximum deviation value.
In a moving state, the quality of the PPG signal is interfered by motion artifacts, and therefore, when there is a deviation value between the amplitude spectrum of the PPG signal and the amplitude spectrum of the acceleration signal in the contrast frequency domain, when the deviation value is within a preset maximum deviation value range, it is indicated that the motion artifact interference in the PPG signal cannot be removed, and the PPG signal cannot be analyzed. The PPG signal quality detection method includes the steps of comparing a PPG signal obtained by a first PPG signal obtaining device with a first acceleration signal obtained by a first PPG signal obtaining device, comparing the PPG signal obtained by the first PPG signal obtaining device with a second PPG signal obtained by a second PPG signal obtaining device with a second acceleration signal obtained by a second PPG signal obtaining device, and comparing the PPG signal obtained by the second PPG signal obtaining device with.
Referring to fig. 3, further optionally, when the deviation value is greater than the preset maximum deviation value, it indicates that the currently obtained PPG signal may be analyzed although being interfered by motion artifacts, and the step S300 further includes:
s312: when the deviation value is larger than the preset maximum deviation value, subtracting the frequency domain signal of the acceleration signal from the frequency domain signal of the PPG signal to obtain a synthesized frequency domain signal;
when the deviation value is greater than the preset maximum deviation, it is described that the currently obtained PPG signal is interfered by motion artifacts, but can be analyzed, and the quality of the PPG signal needs to be further analyzed according to the synthesized frequency domain signal to determine whether the PPG signal can be analyzed.
S313: and acquiring the number of spectral peaks of the synthesized frequency domain signal in a preset spectral range, and determining the quality evaluation result of the PPG signal based on the number of spectral peaks.
In this embodiment, the larger the number of spectral peaks is, the worse the signal quality is, and the number of spectral peaks is inversely correlated with the PPG signal quality. The quality of the current PPG signal can be intuitively known by acquiring the number of spectral peaks of the synthesized frequency domain signal in a preset spectral range, so that a tester can conveniently know the analytic performance of the current PPG signal.
Optionally, in this embodiment, when the number of spectral peaks is less than or equal to a preset minimum number of spectral peaks, it is determined that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed.
The number of spectral peaks of the synthesized frequency domain signal is inversely related to the quality of the PPG signal, and the number of spectral peaks of the synthesized frequency domain signal can be preset according to specific equipment, wherein the smaller the number of spectral peaks of the synthesized frequency domain signal within a preset spectral range obtained within a preset time period is, the better the resolution performance of the PPG signal within the time period is. When the number of spectral peaks of the synthesized frequency domain signal obtained in the preset time period in the preset spectral range exceeds the maximum number of spectral peaks, it is indicated that the PPG signal is greatly interfered, and the obtained PPG signal cannot be analyzed.
In this embodiment, optionally, when the number of spectral peaks is greater than a preset minimum number of spectral peaks, it is indicated that the PPG signal obtained at present is greatly affected by motion artifacts, and the determining a quality evaluation result of the PPG signal based on the number of spectral peaks further includes:
determining the maximum spectral amplitude in the synthesized frequency domain signal, comparing a frequency value corresponding to the maximum spectral amplitude with a preset frequency interval, and determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed when the frequency value corresponding to the maximum spectral amplitude is in the preset frequency interval. The preset frequency interval is not greater than the maximum frequency value of the synthesized frequency domain signal and not less than the minimum frequency value of the synthesized frequency domain signal.
And when the frequency value corresponding to the maximum spectrum amplitude in the synthesized frequency domain signal is not greater than the maximum frequency value of the synthesized frequency domain signal and not less than the minimum frequency value of the synthesized frequency domain signal, the PPG signal can be analyzed.
Optionally, when the number of spectral peaks is greater than a preset minimum number of spectral peaks, it indicates that the currently acquired PPG signal is greatly affected by motion artifacts, and the determining a quality evaluation result of the PPG signal based on the number of spectral peaks further includes:
determining a second large frequency spectrum amplitude in the synthesized frequency domain signal, comparing a frequency value corresponding to the second large frequency spectrum amplitude with a preset frequency interval, and determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed when the frequency value corresponding to the second large frequency spectrum amplitude is in the preset frequency interval.
And when a frequency value corresponding to the second large frequency spectrum amplitude in the synthesized frequency domain signal is not greater than the maximum frequency value of the synthesized frequency domain signal and not less than the minimum frequency value of the synthesized frequency domain signal, the PPG signal can be analyzed. At this time, the quality of the PPG signal at the frequency value corresponding to the maximum spectral amplitude is better than the quality of the PPG signal at the frequency value corresponding to the second maximum spectral amplitude, and the analytic performance of the PPG signal at the frequency value corresponding to the maximum spectral amplitude is better than the PPG signal at the frequency value corresponding to the second maximum spectral amplitude.
Optionally, when the number of spectral peaks is greater than a preset minimum number of spectral peaks, it indicates that the currently acquired PPG signal is greatly affected by motion artifacts, and the determining a quality evaluation result of the PPG signal based on the number of spectral peaks further includes:
determining a third large frequency spectrum amplitude in the synthesized frequency domain signal, comparing a frequency value corresponding to the third large frequency spectrum amplitude with a preset frequency interval, and determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed when the frequency value corresponding to the third large frequency spectrum amplitude is in the preset frequency interval.
And when the frequency value corresponding to the third large frequency spectrum amplitude in the synthesized frequency domain signal is not greater than the maximum frequency value of the synthesized frequency domain signal and not less than the minimum frequency value of the synthesized frequency domain signal, the PPG signal can be analyzed. At this time, the quality of the PPG signal at the frequency value corresponding to the second large spectral amplitude is better than the quality of the PPG signal at the frequency value corresponding to the third large spectral amplitude, and the analytic performance of the PPG signal at the frequency value corresponding to the second large spectral amplitude is better than the PPG signal at the frequency value corresponding to the third large spectral amplitude.
The principles of the present invention are explained in detail below with reference to the accompanying figures 1 to 3. According to the invention, the quality of the PPG signal is determined by acquiring the PPG signal and the acceleration signal output by the acceleration sensor, converting the time domain signal of the PPG signal and the acceleration signal into a frequency domain signal and comparing the PPG signal and the acceleration signal in the frequency domain. In the motion state, the PPG signal may be affected by motion artifacts, so that the quality of the PPG signal is degraded. After the magnitude spectrum of the PPG signal and the magnitude spectrum of the acceleration signal in the contrast frequency domain in the frequency domain are acquired, if the magnitude spectrum of the PPG signal and the magnitude spectrum of the acceleration signal in the contrast frequency domain in the frequency domain are basically consistent or are within a preset goodness of fit range, it is indicated that the motion artifact interferes with the PPG signal seriously, the motion artifact cannot be eliminated from the PPG signal, and the quality evaluation result of the PPG signal is that the PPG signal cannot be analyzed.
When the magnitude spectrum of the PPG signal in the contrast frequency domain in the frequency domain is inconsistent with the magnitude spectrum of the acceleration signal and exceeds a preset goodness of fit range, because the quality of the PPG signal is in a certain range, when the deviation between the magnitude spectrum of the PPG signal in the contrast frequency domain in the frequency domain and the magnitude spectrum of the acceleration signal is smaller than a preset maximum deviation value, it is indicated that the motion artifact interference in the PPG signal cannot be eliminated, and at the moment, the quality evaluation result of the signal is that the PPG signal cannot be analyzed.
And when the deviation of the amplitude spectrum of the PPG signal and the amplitude spectrum of the acceleration signal in the contrast frequency domain in the frequency domain is larger than a preset maximum deviation value, the interference of motion artifacts of the PPG signal can be eliminated, the PPG signal can be analyzed, a synthesized frequency domain signal is calculated, and the quality of the PPG signal is evaluated according to the synthesized frequency domain signal. After the synthesized frequency domain signal is obtained, the number of spectral peaks of the synthesized frequency domain signal in a preset frequency spectrum range is obtained, the more the number of the spectral peaks is, the worse the signal quality is, and then the quality of the current PPG signal can be evaluated according to the number of the spectral peaks.
Meanwhile, after the synthesized frequency domain signal is obtained, the frequencies corresponding to the first three spectral amplitudes of the synthesized frequency domain signal are obtained, the corresponding frequencies are compared with the maximum frequency and the minimum frequency of the synthesized frequency domain signal, and when any one of the frequencies corresponding to the first three spectral amplitudes of the synthesized frequency domain signal is between the maximum frequency and the minimum frequency of the synthesized frequency domain signal, the PPG signal obtained currently can be analyzed.
The invention also proposes an embodiment of a PPG signal quality evaluation device performing the method according to any of the embodiments described above. The device comprises: a signal generation unit 1004 for outputting a PPG signal and an acceleration signal; a processor 1001; and a memory 1002 for storing said PPG signal quality assessment program executable on said processor; when executed by the processor, the PPG signal quality evaluation program implements the steps of the PPG signal quality evaluation method according to any of the embodiments described above.
The signal generation unit 1004 is configured to output a PPG signal and an acceleration signal. The processor 1001 may be a CPU, and the processor 1001 may include a network interface, a user interface, a communication bus 1003, and the like. Wherein a communication bus 1002 is used to enable connective communication between these components. The user interface may comprise a Display screen (Display), an input unit such as keys, and the optional user interface may also comprise a standard wired interface, a wireless interface. The network interface may optionally include a standard wired interface, a wireless interface (e.g., WI-FI interface), a serial port, etc. The memory 1002 may be a high-speed RAM memory 1002, or may be a non-volatile memory 1002 (e.g., a disk memory 1002). The memory 1002 may alternatively be a storage device separate from the processor 1001. The processor 1001 calls the PPG signal quality evaluation program stored in the memory and the PPG signal and the acceleration signal obtained by the signal generation unit, and performs PPG signal quality evaluation.
The invention also provides an embodiment of the wearable device. The wearable device stores the device for executing the PPG signal quality evaluation method according to the embodiment. The wearable device can be a smart watch or the like.
The invention also proposes an embodiment of a storage medium. The storage medium stores an evaluation program of a PPG signal quality device, which when executed by a processor implements the steps of the PPG signal quality evaluation method according to any of the embodiments described above. The readable storage medium may be a U disk, a removable hard disk, a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and the like.
Claims (12)
1. A PPG signal quality assessment method for assessing whether a PPG signal acquired by a wearable device can be analyzed, wherein the wearable device is provided with an acceleration sensor, and the PPG signal quality assessment method comprises the following steps:
acquiring a PPG signal acquired by wearable equipment and an acceleration signal output by an acceleration sensor;
carrying out time domain to frequency domain conversion on the acquired PPG signal and the acceleration signal to obtain the PPG signal and the acceleration signal in a frequency domain; and
and comparing the amplitude spectrum of the PPG signal in the frequency domain with the amplitude spectrum of the acceleration signal to obtain a quality evaluation result of the PPG signal.
2. The PPG signal quality evaluation method of claim 1, wherein the comparing the amplitude spectrum of the PPG signal in the frequency domain with the amplitude spectrum of the acceleration signal to obtain the quality evaluation result of the PPG signal comprises:
and when the coincidence degree of the amplitude spectrum of the PPG signal and the amplitude spectrum of the acceleration signal in the frequency domain reaches a preset coincidence degree range, determining that the quality evaluation result of the PPG signal is that the PPG signal cannot be analyzed.
3. The PPG signal quality evaluation method of claim 1, wherein the comparing the amplitude spectrum of the PPG signal in the frequency domain with the amplitude spectrum of the acceleration signal to obtain the quality evaluation result of the PPG signal further comprises:
when the magnitude spectrum of the PPG signal and the magnitude spectrum of the acceleration signal in the frequency domain do not reach a preset goodness of fit range, calculating a deviation value of the magnitude spectrum of the PPG signal and the magnitude spectrum of the acceleration signal in the frequency domain; and
and comparing the deviation value with a preset maximum deviation value, and determining that the quality evaluation result of the PPG signal is that the PPG signal can not be analyzed when the deviation value is smaller than or equal to the preset maximum deviation value.
4. The PPG signal quality evaluation method of claim 3, wherein the comparing the amplitude spectrum of the PPG signal in the frequency domain with the amplitude spectrum of the acceleration signal to obtain the evaluation result of the PPG signal quality further comprises:
when the deviation value is larger than the preset maximum deviation value, subtracting the frequency domain signal of the acceleration signal from the frequency domain signal of the PPG signal to obtain a synthesized frequency domain signal; and
and acquiring the number of spectral peaks of the synthesized frequency domain signal in a preset spectral range, and determining the quality evaluation result of the PPG signal based on the number of spectral peaks.
5. The PPG signal quality assessment method of claim 4, wherein said determining a quality assessment result of the PPG signal based on the number of spectral peaks comprises:
the number of spectral peaks is inversely related to the PPG signal quality.
6. The PPG signal quality assessment method of claim 4, wherein said determining a quality assessment result of the PPG signal based on the number of spectral peaks comprises:
and when the number of the spectrum peaks is less than or equal to the preset minimum number of the spectrum peaks, determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed.
7. The PPG signal quality assessment method of claim 4, wherein when the number of spectral peaks is greater than a preset minimum number of spectral peaks, said determining the quality assessment result of the PPG signal based on the number of spectral peaks further comprises:
determining the maximum spectral amplitude in the synthesized frequency domain signal, comparing a frequency value corresponding to the maximum spectral amplitude with a preset frequency interval, and determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed when the frequency value corresponding to the maximum spectral amplitude is in the preset frequency interval; and/or
Determining a second large frequency spectrum amplitude in the synthesized frequency domain signal, comparing a frequency value corresponding to the second large frequency spectrum amplitude with a preset frequency interval, and determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed when the frequency value corresponding to the second large frequency spectrum amplitude is in the preset frequency interval; and/or
Determining a third large frequency spectrum amplitude in the synthesized frequency domain signal, comparing a frequency value corresponding to the third large frequency spectrum amplitude with a preset frequency interval, and determining that the quality evaluation result of the PPG signal is that the PPG signal can be analyzed when the frequency value corresponding to the third large frequency spectrum amplitude is in the preset frequency interval;
the preset frequency interval is not greater than the maximum frequency value of the synthesized frequency domain signal and not less than the minimum frequency value of the synthesized frequency domain signal.
8. The PPG signal quality assessment method of claim 4, wherein when the number of spectral peaks is greater than a preset minimum number of spectral peaks, said determining the quality assessment result of the PPG signal based on the number of spectral peaks further comprises:
determining the maximum spectral amplitude, the second large spectral amplitude and the third large spectral amplitude in the synthesized frequency domain signal, wherein the quality of the PPG signal decreases under frequency values respectively corresponding to the maximum spectral amplitude, the second large spectral amplitude and the third large spectral amplitude.
9. The PPG signal quality assessment method of claim 1, wherein after the step of acquiring PPG signals acquired by a wearable device and acceleration signals output by an acceleration sensor, the PPG signal quality assessment method further comprises:
and carrying out band-pass filtering and denoising on the acquired PPG signal and the acceleration signal to obtain the PPG signal and the acceleration signal in a time domain.
10. A PPG signal quality assessment device for performing the method of any of claims 1 to 9, characterized in that the device comprises:
the signal generating unit is used for outputting a PPG signal and an acceleration signal;
a processor; and
a memory for storing the PPG signal quality assessment program executable on the processor; the PPG signal quality evaluation procedure, when executed by the processor, implements the steps of the PPG signal quality evaluation method of any of claims 1 to 9.
11. A wearable device storing the apparatus for performing the PPG signal quality assessment method of claim 10.
12. A storage medium storing an evaluation program of a PPG signal quality device, which when executed by a processor implements the steps of the PPG signal quality evaluation method according to any of claims 1 to 9.
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