Heart rate continuous detection method and device, electronic equipment and storage medium

Abstract

The invention provides a heart rate continuous detection method and device, electronic equipment and a storage medium. According to the method, a cache queue is set for the latest M data points in a reference PPG signal, a reference heart rate value is determined according to the latest data points in the cache queue at set intervals, and an initial heart rate value is determined until it is detected that the reference heart rate value is relatively stable; further taking the initial heart rate value as a current heart rate value, determining candidate frequency values possibly corresponding to the updated target heart rate value according to the current heart rate value and a preset heart rate resolution after a second time interval, and fitting each candidate frequency value and data points stored in a current cache queue based on a preset fitting curve to obtain a target heart rate value; and determining the heart rate value corresponding to the candidate frequency value corresponding to the maximum fitting result as the target heart rate value, thereby reducing the frequency resolution under the condition of not influencing the time domain resolution so as to obtain a more accurate heart rate value.

Description

Technical Field

[0001] The present application relates to the field of heart rate detection technology, and in particular to a method, device, electronic device and storage medium for continuous heart rate detection. Background Art

[0002] Currently, many wearable devices have the function of real-time heart rate detection. The current method for continuous heart rate detection is usually to determine the spectrum interval to which the current heart rate value belongs based on the collected photoplethysmography (PPG) signal based on Fourier transform technology, and then determine the frequency value corresponding to the current heart rate value from the interval to obtain the final heart rate value. However, the heart rate detection result obtained by the above method is not accurate enough. Summary of the invention

[0003] In view of this, the present application provides a continuous heart rate detection method, device, electronic device and storage medium to improve the accuracy of continuous heart rate detection results.

[0004] The technical solutions provided by this application are as follows:

[0005] According to an embodiment of the first aspect of the present application, a method for continuous heart rate detection is provided, the method comprising:

[0006] Setting a cache queue, the cache queue is used to store the latest M data points in the reference photoplethysmography (PPG) signal obtained after preprocessing, where M is determined according to the sampling frequency of the reference PPG signal;

[0007] In the case where M data points have been stored in the cache queue, at every first time interval, a reference heart rate value corresponding to the M data points is determined according to the latest M data points stored in the cache queue, until the absolute value of the difference between any two adjacent reference heart rate values ​​in the consecutive K reference heart rate values ​​is less than a preset threshold, and then an initial heart rate value is determined according to the K reference heart rate values;

[0008] Taking the initial heart rate value as the current heart rate value, after a second time interval, determining a frequency value sequence corresponding to the current heart rate value according to the current heart rate value and a preset heart rate resolution; the frequency value sequence records all possible candidate frequency values ​​corresponding to the target heart rate value obtained after the current heart rate value is updated;

[0009] For each candidate frequency value in the frequency value sequence, the latest M data points stored in the cache sequence are fitted according to a preset fitting curve and the candidate frequency value;

[0010] The candidate frequency value corresponding to the maximum fitting result is determined as the target frequency value; the target heart rate value is determined according to the target frequency value; and the current heart rate value is updated to the target heart rate value.

[0011] Optionally, after updating the current heart rate value to the target heart rate value, the method further includes:

[0012] The target heart rate value is used as the current heart rate value, and the step of determining the frequency value series corresponding to the current heart rate value according to the current heart rate value and the preset heart rate resolution after the second time interval has passed is returned until an instruction to stop heart rate detection is received.

[0013] Optionally, the reference photoplethysmogram (PPG) signal is obtained by:

[0014] The obtained original acceleration sensor ACC signal and the original PPG signal are filtered by the configured filter to obtain a candidate ACC signal and a candidate PPG signal;

[0015] The candidate ACC signal is input into a configured adaptive filter to obtain a filter output signal, and the reference PPG signal is determined according to the candidate PPG signal and the filter output signal.

[0016] Optionally, determining the reference heart rate values ​​corresponding to the M data points according to the latest M data points stored in the cache queue includes:

[0017] Perform a fast Fourier transform (FFT) on the latest M data points stored in the cache queue to obtain a frequency spectrum corresponding to the M data points;

[0018] The frequency value corresponding to the spectrum peak is determined according to the spectrum diagram, and the reference heart rate value is determined according to the frequency value corresponding to the spectrum peak.

[0019] Optionally, determining the initial heart rate value according to the K reference heart rate values ​​includes:

[0020] Taking the last reference heart rate value among the K reference heart rate values ​​as the initial heart rate value;

[0021] Alternatively, an average value of the K reference heart rate values ​​is used as the initial heart rate value.

[0022] Optionally, determining a frequency value series corresponding to the current heart rate value according to the current heart rate value and a preset heart rate resolution includes:

[0023] Generate a heart rate value series with the current heart rate value as the center and the heart rate resolution as the interval; wherein the heart rate value series records all possible target heart rate values ​​obtained after the current heart rate value is updated; the number of heart rate values ​​included in the heart rate value series is determined according to the maximum range of the heart rate change in the second time interval and the heart rate resolution;

[0024] The heart rate value series is converted into a frequency value series corresponding to the heart rate values.

[0025] According to an embodiment of the second aspect of the present application, a device for continuous heart rate detection is provided, the device comprising:

[0026] A setting unit, used to set a cache queue, where the cache queue is used to store the latest M data points in the reference photoplethysmography (PPG) signal obtained after preprocessing, where M is determined according to a sampling frequency of the reference PPG signal;

[0027] a determining unit, configured to determine, at a first time interval, a reference heart rate value corresponding to the M data points according to the latest M data points stored in the cache queue, when M data points have been stored in the cache queue, until the absolute value of the difference between any two adjacent reference heart rate values ​​in the consecutive K reference heart rate values ​​is less than a preset threshold, and then determine the initial heart rate value according to the K reference heart rate values;

[0028] Taking the initial heart rate value as the current heart rate value, after a second time interval, determining a frequency value sequence corresponding to the current heart rate value according to the current heart rate value and a preset heart rate resolution; the frequency value sequence records all possible candidate frequency values ​​corresponding to the target heart rate value obtained after the current heart rate value is updated;

[0029] A fitting unit, for fitting, for each candidate frequency value in the frequency value sequence, the latest M data points stored in the cache sequence according to a preset fitting curve and the candidate frequency value;

[0030] An updating unit is used to determine the candidate frequency value corresponding to the maximum fitting result as the target frequency value; determine the target heart rate value according to the target frequency value; and update the current heart rate value to the target heart rate value.

[0031] Optionally, after updating the current heart rate value to the target heart rate value, the updating unit is further configured to:

[0032] Taking the target heart rate value as the current heart rate value, returning to the step of determining the frequency value sequence corresponding to the current heart rate value according to the current heart rate value and a preset heart rate resolution after the second time interval has passed, until receiving an instruction to stop heart rate detection;

[0033] And / or, the reference photoplethysmogram (PPG) signal is obtained by:

[0034] The obtained original acceleration sensor ACC signal and the original PPG signal are filtered by the configured filter to obtain a candidate ACC signal and a candidate PPG signal;

[0035] Input the candidate ACC signal into a configured adaptive filter to obtain a filter output signal, and determine the reference PPG signal according to the candidate PPG signal and the filter output signal;

[0036] And / or, the determining unit is specifically configured to:

[0037] Perform a fast Fourier transform (FFT) on the latest M data points stored in the cache queue to obtain a frequency spectrum corresponding to the M data points;

[0038] Determine the frequency value corresponding to the spectrum peak according to the spectrum graph, and determine the reference heart rate value according to the frequency value corresponding to the spectrum peak;

[0039] And / or, the determining unit is specifically configured to:

[0040] Taking the last reference heart rate value among the K reference heart rate values ​​as the initial heart rate value;

[0041] Alternatively, taking the average of the K reference heart rate values ​​as the initial heart rate value;

[0042] And / or, the determining unit is specifically configured to:

[0043] Generate a heart rate value series with the current heart rate value as the center and the heart rate resolution as the interval; wherein the heart rate value series records all possible target heart rate values ​​obtained after the current heart rate value is updated; the number of heart rate values ​​included in the heart rate value series is determined according to the maximum range of the heart rate change in the second time interval and the heart rate resolution;

[0044] The heart rate value series is converted into a frequency value series corresponding to the heart rate values.

[0045] According to an embodiment of the third aspect of the present application, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method described in the first aspect when executing the program.

[0046] According to an embodiment of the fourth aspect of the present application, a computer-readable storage medium is provided, on which a number of computer instructions are stored. When the computer instructions are executed, the method described in the first aspect is implemented.

[0047] It can be seen from the above technical scheme that the present application sets up a cache queue for the latest M data points in the reference photoplethysmogram (PPG) signal obtained after preprocessing, and determines a reference heart rate value in the cache queue based on the latest data point at regular intervals until the detected K consecutive reference heart rate values ​​are relatively stable, and then determines the initial heart rate value based on the K reference heart rate values; further, the initial heart rate value is used as the current heart rate value, and after a second time interval, the candidate frequency value that may correspond to the updated target heart rate value is determined based on the current heart rate value and the preset heart rate resolution, and fitting is performed based on the preset fitting curve for each candidate frequency value and the data points stored in the current cache queue, and the heart rate value corresponding to the candidate frequency value corresponding to the maximum fitting result is determined as the target heart rate value, thereby avoiding the use of Fourier transform technology to update the heart rate value, and reducing the frequency resolution without affecting the time domain resolution, thereby obtaining a more accurate heart rate value. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0049] Figure 1 A schematic diagram of the PPG signal generation principle provided in an embodiment of the present application;

[0050] Figure 2 A flowchart of a method for continuous heart rate detection provided in an embodiment of the present application;

[0051] Figure 3 A schematic diagram of preprocessing based on an adaptive filter provided in an embodiment of the present application;

[0052] Figure 4 A schematic diagram of the overall process of the continuous heart rate detection method provided in an embodiment of the present application;

[0053] Figure 5 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application;

[0054] Figure 6 A structural diagram of a continuous heart rate detection device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0055] In order to enable those skilled in the art to better understand the technical solutions provided by the embodiments of the present application and to make the above-mentioned purposes, features and advantages of the embodiments of the present application more obvious and understandable, the technical solutions in the embodiments of the present application are further described in detail below in conjunction with the accompanying drawings.

[0056] Currently, many wearable devices have the function of continuous heart rate detection. The current method for continuous heart rate detection is usually to determine the spectrum interval to which the current heart rate value belongs based on the collected photoplethysmography (PPG) signal based on Fourier transform technology, and then determine the frequency value corresponding to the current heart rate value from the interval to obtain the final heart rate value.

[0057] Combine the following Figure 1 The following briefly describes the method of collecting PPG signals.

[0058] Please refer to Figure 1 , Figure 1 Schematic diagram of the PPG signal generation principle provided in an embodiment of the present application.

[0059] like Figure 1 As shown, the PPG sensor consists of at least a pair of light emitting diodes (LEDs) and photodetectors (PDs).

[0060] The light emitting diode is used to provide a light source to illuminate the skin, and the photodetector is used to generate different signals according to the intensity changes of the detected light.

[0061] Common PGG sensors usually include the following two arrangements: projection sensor ( Figure 1 left) and reflective sensors ( Figure 1 right side of the figure).

[0062] For projection sensors, light-emitting diodes are used as light sources to illuminate the skin, and photodetectors are used to receive light transmitted from the other side of the skin and detect changes in light intensity. When the heart contracts, the blood flow in the blood vessels increases, the light absorbed by the blood increases, and the light transmitted increases accordingly. Conversely, when the heart relaxes, the intensity of the transmitted light decreases.

[0063] For example, in a reflective sensor, a light-emitting diode is used as a light source to illuminate the skin, and a photodetector is used to receive the light reflected by the skin and detect changes in the light intensity. When the heart contracts, the blood flow in the blood vessels increases, the light absorbed by the blood increases, and the light reflected back decreases. Conversely, when the heart relaxes, the intensity of the light reflected back increases.

[0064] Under this mechanism, the fluctuating PPG signal generated by the periodic contraction and relaxation of the heart can be used to monitor heart rate.

[0065] This concludes Figure 1 Description.

[0066] At present, the heart rate value obtained based on Fourier transform is not accurate enough, which is limited by the frequency resolution of Fourier transform technology. For example, assuming that the sampling frequency of the PPG signal is 25Hz, the number of sampling points is 256, and the signal is Fourier transformed, the duration of the signal involved in the calculation is about 10 seconds (256 / 25), then the frequency resolution of the obtained spectrum is 25 / 256=0.0977Hz, and the corresponding heart rate resolution is 0.0977*60=5.86bpm, which will result in a larger heart rate resolution, unable to detect smaller heart rate changes, and the accuracy cannot be met.

[0067] Based on this, the present application proposes a method for continuous heart rate detection to improve the accuracy of continuous heart rate detection.

[0068] Please refer to Figure 2 , Figure 2 A flowchart of a continuous heart rate detection method provided in an embodiment of the present application.

[0069] As an embodiment, the method can be applied to wearable devices, such as smart bracelets, smart watches, electrocardiogram monitors, finger-clip heart rate monitors, etc., and the present application does not limit this.

[0070] like Figure 2 As shown, the method may include the following steps:

[0071] Step 201, setting a cache queue.

[0072] In this embodiment, in order to detect continuous heart rate, it is first necessary to determine the initial value of the heart rate when the detection starts. In order to determine the initial heart rate value, this embodiment pre-sets a cache queue for storing a reference photoplethysmogram (PPG) signal. The cache queue is used to store the latest M data points in the preprocessed reference photoplethysmogram (PPG) signal. The value of M can be determined based on the sampling frequency of the reference PPG signal.

[0073] Among them, the reference PPG signal is a signal obtained by preprocessing the original PPG signal and the original ACC signal. Each data point in the reference PPG signal represents the instantaneous value of the blood volume in the blood vessel at the measurement position at that moment. The heart rate value can be obtained by analyzing multiple data points, that is, the instantaneous values ​​of blood volume at multiple moments.

[0074] As an embodiment, the reference PPG signal may be obtained in the following manner:

[0075] The obtained original acceleration sensor ACC signal and the original PPG signal are filtered by the configured filter to obtain a candidate ACC signal and a candidate PPG signal;

[0076] The candidate ACC signal is input into the configured adaptive filter to obtain a filter output signal, and a reference PPG signal is determined according to the candidate PPG signal and the filter output signal.

[0077] In this embodiment, after the original PPG signal is acquired through the PPG sensor and the original ACC signal is acquired through the acceleration sensor, since the original PPG signal may be affected by ambient light, the original PPG signal and the original ACC signal may have high-frequency noise and low-frequency baseline drift, so the original PPG signal and the original ACC signal may be preprocessed to eliminate the above-mentioned influences.

[0078] As an embodiment, in order to eliminate the influence of ambient light, the analog-to-digital conversion value collected when the LED light in the PPG sensor is off can be subtracted from the analog-to-digital conversion value collected when the LED light in the PPG sensor is on; in order to eliminate the influence of high-frequency noise and low-frequency baseline drift, the original PPG signal and the original ACC signal can be passed through a preset filter such as a bandpass filter, and the present application does not limit this.

[0079] In this embodiment, motion artifacts may also exist in the PPG signal, and the influence of the motion artifacts can be eliminated by setting an adaptive filter.

[0080] As an example, please refer to Figure 3 , Figure 3 A schematic diagram of preprocessing based on an adaptive filter provided in an embodiment of the present application.

[0081] like Figure 3 As shown, the ACC signal (referred to as the candidate ACC signal) obtained after eliminating the influence of ambient light, high-frequency noise and low-frequency baseline drift can be used as the input signal of the adaptive filter, the PPG signal (referred to as the candidate PPG signal) obtained after eliminating the influence of ambient light, high-frequency noise and low-frequency baseline drift can be used as the expected signal, and the difference between the expected signal and the filter output signal can be used as the error signal (i.e., the reference PPG signal).

[0082] After the error signal is used as a reference PPG signal stored in the cache queue, the parameters of the adaptive filter can be further updated based on the adaptive algorithm according to the error signal.

[0083] As an embodiment, the adaptive algorithm for updating the filter parameters may be a least mean squares (LMS) algorithm or a recursive least squares (RLS) algorithm, etc., which is not limited in the present application.

[0084] This concludes Figure 3 Description.

[0085] After obtaining the reference PPG signal, the reference PPG signal can be stored in a cache queue. It should be noted that the PPG signal stored in the cache queue changes dynamically, and the cache queue always stores only the latest M data points in the PPG signal. The value of M can be set according to an empirical value, such as determined according to the sampling frequency of the reference PPG signal, and set to 4 times the sampling frequency of the reference PPG signal, etc. This application does not impose any restrictions on this.

[0086] At this point, the description of step 201 ends, and step 202 is executed next.

[0087] Step 202, when M data points have been stored in the cache queue, at every first time interval, the reference heart rate values ​​corresponding to the M data points are determined based on the latest M data points stored in the cache queue, until the absolute value of the difference between any two adjacent reference heart rate values ​​among K consecutive reference heart rate values ​​is less than a preset threshold, then the initial heart rate value is determined based on the K reference heart rate values, and K is greater than 1.

[0088] In this embodiment, as the PPG sensor collects the initial PPG signal and obtains the reference PPT signal after processing, M data points are gradually stored in the cache queue. When M data points have been stored in the cache queue, a corresponding reference heart rate value can be determined at every first time interval based on the most recently stored M data points.

[0089] As an embodiment, a method for determining reference heart rate values ​​corresponding to the M latest data points stored in a cache queue may include:

[0090] Perform a fast Fourier transform (FFT) on the latest M data points stored in the cache queue to obtain a frequency spectrum corresponding to the M data points;

[0091] The frequency value corresponding to the spectrum peak is determined according to the spectrum diagram, and the reference heart rate value is determined according to the frequency value corresponding to the spectrum peak.

[0092] In this embodiment, the latest M data points stored in the cache queue can be subjected to a fast Fourier transform to obtain a spectrum diagram corresponding to the M data points. The spectrum diagram records the signal amplitude corresponding to each frequency. At this time, the frequency value corresponding to the spectral line (i.e., spectral peak) with the largest signal amplitude in the spectrum diagram can be used as the reference frequency value of the M data points, and the heart rate value corresponding to the frequency value can be determined as the reference heart rate value corresponding to the M data points.

[0093] In this embodiment, at every first time interval, a reference heart rate value is determined based on the latest M data points stored in the current cache queue. At the same time, the currently determined reference heart rate value can also be compared with the previously determined reference heart rate value. If the absolute value of the difference between any two adjacent reference heart rate values ​​among K consecutive reference heart rate values ​​is less than the preset threshold, it indicates that the heart rate value detected at this time is relatively stable, and the initial heart rate value can be determined based on the K consecutive reference heart rate values.

[0094] In this embodiment, the method for determining the initial heart rate value according to K reference heart rate values ​​may include:

[0095] The last reference heart rate value among the K reference heart rate values ​​is used as the initial heart rate value;

[0096] Alternatively, the average of K reference heart rate values ​​is used as the initial heart rate value, which is not limited in the present application.

[0097] In this embodiment, K is an integer greater than 1 and can be set according to actual needs. At the same time, the first time interval can also be set according to actual needs, and this application does not limit this.

[0098] At this point, the description of step 202 ends, and step 203 is executed next.

[0099] Step 203: Taking the initial heart rate value as the current heart rate value, after a second time interval, determining a frequency value series corresponding to the current heart rate value according to the current heart rate value and a preset heart rate resolution.

[0100] In this embodiment, step 201 and step 202 complete the determination of the initial heart rate value. After the initial heart rate value is determined, the initial heart rate value can be used as the current heart rate value and displayed on the wearable device as the first heart rate value detected by the wearable device after the user initiates the heart rate detection instruction. Further, if the user does not issue an instruction to stop the heart rate detection, the heart rate value needs to be continuously detected and updated at intervals.

[0101] In this embodiment, the second time interval is the interval duration for updating the heart rate value, which can be adjusted according to actual needs, and this application does not impose any restrictions on this.

[0102] As an embodiment, the M data points stored in the cache queue may be the latest M data points in the reference PPG signal, or may be any M consecutive data points within the second time interval, which is not limited in the present application.

[0103] In this embodiment, after the second time interval, the current heart rate value needs to be updated. At this time, the frequency value series corresponding to the current heart rate value can be determined based on the current heart rate value and the preset heart rate resolution, wherein the frequency value series records all possible candidate frequency values ​​corresponding to the target heart rate value obtained after the current heart rate value is updated.

[0104] As an embodiment, the method for determining the frequency value series corresponding to the current heart rate value according to the current heart rate value and the preset heart rate resolution may specifically include:

[0105] Generate a heart rate value series with the current heart rate value as the center and the heart rate resolution as the interval; wherein the heart rate value series records all possible target heart rate values ​​obtained after the current heart rate value is updated; the number of heart rate values ​​included in the heart rate value series is determined according to the maximum range of the heart rate change in the second time interval and the heart rate resolution;

[0106] Convert the heart rate value series into the frequency value series corresponding to the heart rate values.

[0107] In this embodiment, the current heart rate value can be updated based on the pre-set heart rate resolution and the second time interval. The heart rate resolution is the smallest heart rate change that the system can distinguish. The first item of the heart rate value series is the minimum value that the heart rate value may take in the second time interval, and the last item of the heart rate value series is the maximum value that the heart rate value may take in the second time interval.

[0108] For example, the set heart rate resolution may be recorded as Δhr, and the current heart rate value may be recorded as hr. Then, the method for determining the frequency value series may be:

[0109] With hr as the center and Δhr as the interval, a heart rate value sequence with a length of 2N+1 is generated, which is an arithmetic progression: hr-Δhr*N, hr-Δhr*(N-1),…, hr-Δhr, hr, hr+Δhr,…, hr+Δhr*(N-1), hr+hr*N. Among them, N is an empirical value determined according to the maximum range of possible changes in heart rate within the second time interval and the heart rate resolution.

[0110] For example, if the second time interval is 2 seconds, the maximum range of possible changes in heart rate within 2 seconds is 5 beats per minute (bpm), and the heart rate resolution is 1bpm. That is, assuming the current heart rate is 80bpm, the possible values ​​of the heart rate after changing within 2 seconds are 75bpm, 76bpm, 77bpm, 78bpm, 79bpm, 80bpm, 81bpm, 82bpm, 83bpm, 84bpm, and 85bpm, for a total of 11 possible values. At this time, the value of N is 5.

[0111] After the heart rate value series is determined, the heart rate value series can be converted into a corresponding frequency value series: f-Δf*N, f-Δf*(N-1),…, f-Δf, f, f+Δf,…, f+Δf*(N-1), f+Δf*N, where the frequency values ​​in the frequency value series correspond to the heart rate values ​​in the heart rate value series. Among them, because the heart rate value is the number of heart beats per minute and the frequency value is the number of heart beats per second, the frequency value corresponding to the heart rate value is the heart rate value divided by 60.

[0112] As an embodiment, multiple candidate frequency values ​​may be directly generated according to the initial heart rate value, for example, by directly subtracting or adding a target experience value from the initial heart rate value hr to obtain multiple candidate frequency values, which is not limited in the present application.

[0113] At this point, the description of step 203 ends, and step 204 is executed next.

[0114] Step 204 : for each candidate frequency value in the frequency value series, the latest M data points stored in the cache series are fitted according to a preset fitting curve and the candidate frequency value.

[0115] In this embodiment, for the frequency value series determined in step 203, fitting can be performed for each candidate frequency value according to a preset fitting curve and the latest M data points stored in the cache series.

[0116] As an example, the fitting curve may be determined as:

[0117]

[0118] Among them, y is the reference PPG signal corresponding to the M data points stored in the cache queue, that is, the instantaneous value of the blood volume in the blood vessel at the measurement position at that moment, f is each candidate frequency value in the above frequency value series, and t is the duration of the time series generated according to the sampling rate and the cache queue length.

[0119] By fitting an amplitude Y and phase for each candidate frequency value

[0120] At this point, the description of step 204 ends, and step 205 is executed next.

[0121] Step 205, determining the candidate frequency value corresponding to the maximum fitting result as the target frequency value; determining the target heart rate value according to the target frequency value; and updating the current heart rate value to the target heart rate value.

[0122] In this embodiment, since there are 2N+1 candidate frequency values ​​in total, after fitting each candidate frequency value, 2N+1 amplitudes Y can be obtained, and the candidate frequency value corresponding to the largest amplitude Y can be selected from the 2N+1 amplitudes Y as the target frequency value corresponding to the target heart rate value to be updated, that is, the candidate frequency value corresponding to the maximum fitting result is determined as the target frequency value, and the corresponding target heart rate value is further determined based on the target frequency value, and the target heart rate value is used as the updated current heart rate value and displayed on the wearable device.

[0123] This concludes the description of step 205.

[0124] The above process is the overall process of one update. In fact, if the user does not issue an instruction to stop the detection, the heart rate value needs to be updated multiple times.

[0125] As an embodiment, after the current heart rate value is updated to the target heart rate value, the target heart rate value can be used as the current heart rate value, and the step of returning to determine the frequency value series corresponding to the current heart rate value based on the current heart rate value and the preset heart rate resolution after a second time interval has passed, until an instruction to stop heart rate detection is received.

[0126] In this embodiment, after completing one update, the target heart rate value can be used as the new current heart rate value, and the process returns to the step of determining the target heart rate value to determine the next target heart rate value that needs to be updated.

[0127] This concludes Figure 1 Description of the flow chart of the heart rate continuous detection method.

[0128] The present application sets a cache queue for the latest M data points in the reference photoplethysmogram (PPG) signal obtained after preprocessing, and determines a reference heart rate value in the cache queue based on the latest data point at regular intervals until the detected K consecutive reference heart rate values ​​are relatively stable, and then determines the initial heart rate value based on the K reference heart rate values; further, the initial heart rate value is used as the current heart rate value, and after a second time interval, the candidate frequency value that may correspond to the updated target heart rate value is determined based on the current heart rate value and a preset heart rate resolution, and fitting is performed based on a preset fitting curve for each candidate frequency value and the data points stored in the current cache queue, and the heart rate value corresponding to the candidate frequency value corresponding to the maximum fitting result is determined as the target heart rate value, thereby avoiding the use of Fourier transform technology to update the heart rate value, and reducing the frequency resolution without affecting the time domain resolution, so as to obtain a more accurate heart rate value.

[0129] Furthermore, the solution proposed in the present application can output the current heart rate value with any set accuracy without affecting the time domain resolution, that is, the current heart rate value can be updated with a set accuracy at a set update time interval.

[0130] Below through Figure 4 The overall process of the continuous heart rate detection method is introduced.

[0131] Please refer to Figure 4 , Figure 4 A schematic diagram of the overall process of the continuous heart rate detection method provided in an embodiment of the present application.

[0132] like Figure 4 As shown, the method may include the following steps:

[0133] Obtain PPG signals and ACC signals from wearable devices and pre-process the signals.

[0134] In this embodiment, the preprocessing mentioned here refers to the processing of eliminating the influence of ambient light, high-frequency noise, low-frequency baseline drift, etc., which will not be described in detail here.

[0135] The preprocessed PPG signal and the ACC signal are combined to obtain an adaptively filtered PPG signal.

[0136] In this embodiment, the preprocessed signal may be adaptively filtered to obtain an adaptively filtered PPG signal, i.e., a reference PPG signal, which will not be described in detail here.

[0137] Set the cache queue and update it in real time to complete the heart rate initialization.

[0138] In this embodiment, after the reference PPG signal is determined, Figure 2 The method shown processes it to obtain the initial heart rate value.

[0139] The current heart rate value is updated with the set accuracy and time interval.

[0140] In this embodiment, after the initial heart rate value is determined, the initial heart rate value can be used as the current heart rate value. Figure 2 The method shown further updates the current heart rate value to determine the target heart rate value.

[0141] This concludes Figure 4 Description of the flow chart in .

[0142] Please refer to Figure 5 , Figure 5It is a schematic structural diagram of an electronic device proposed in an embodiment of the present application. At the hardware level, the electronic device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory, and of course may also include hardware required for other services. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it, forming a terminal interaction device at the logical level. Of course, in addition to the software implementation method, this application does not exclude other implementation methods, such as logic devices or a combination of software and hardware, etc., that is to say, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0143] Please refer to Figure 6 , Figure 6 : is a structural diagram of a continuous heart rate detection device proposed in an embodiment of the present application. Figure 6 As shown, the heart rate continuous detection device may include a setting unit 601, a determination unit 602, a fitting unit 603 and an updating unit 604. Specifically, the device includes:

[0144] A setting unit 601 is used to set a cache queue, where the cache queue is used to store the latest M data points in the preprocessed reference photoplethysmography (PPG) signal, where M is determined according to a sampling frequency of the reference PPG signal;

[0145] The determining unit 602 is configured to determine, at a first time interval, a reference heart rate value corresponding to the M data points according to the latest M data points stored in the cache queue, when M data points have been stored in the cache queue, until the absolute value of the difference between any two adjacent reference heart rate values ​​in the consecutive K reference heart rate values ​​is less than a preset threshold, and then determine an initial heart rate value according to the K reference heart rate values;

[0146] Taking the initial heart rate value as the current heart rate value, after a second time interval, determining a frequency value sequence corresponding to the current heart rate value according to the current heart rate value and a preset heart rate resolution; the frequency value sequence records all possible candidate frequency values ​​corresponding to the target heart rate value obtained after the current heart rate value is updated;

[0147] A fitting unit 603 is used to fit the latest M data points stored in the cache sequence according to a preset fitting curve and the candidate frequency value for each candidate frequency value in the frequency value sequence;

[0148] The updating unit 604 is used to determine the candidate frequency value corresponding to the maximum fitting result as the target frequency value; determine the target heart rate value according to the target frequency value; and update the current heart rate value to the target heart rate value.

[0149] Optionally, after updating the current heart rate value to the target heart rate value, the updating unit 604 is further configured to:

[0150] Taking the target heart rate value as the current heart rate value, returning to the step of determining a frequency value sequence corresponding to the current heart rate value according to the current heart rate value and a preset heart rate resolution after a second time interval has passed, until receiving an instruction to stop heart rate detection;

[0151] And / or, the reference photoplethysmography (PPG) signal is obtained by:

[0152] The obtained original acceleration sensor ACC signal and the original PPG signal are filtered by the configured filter to obtain a candidate ACC signal and a candidate PPG signal;

[0153] Input the candidate ACC signal into the configured adaptive filter to obtain a filter output signal, and determine a reference PPG signal according to the candidate PPG signal and the filter output signal;

[0154] And / or, the determining unit 602 is specifically configured to:

[0155] Perform a fast Fourier transform (FFT) on the latest M data points stored in the cache queue to obtain a frequency spectrum corresponding to the M data points;

[0156] Determine the frequency value corresponding to the spectrum peak according to the spectrum diagram, and determine the reference heart rate value according to the frequency value corresponding to the spectrum peak;

[0157] And / or, the determining unit 602 is specifically configured to:

[0158] The last reference heart rate value among the K reference heart rate values ​​is used as the initial heart rate value;

[0159] Alternatively, the average of K reference heart rate values ​​is used as the initial heart rate value;

[0160] And / or, the determining unit 602 is specifically configured to:

[0161] Generate a heart rate value series with the current heart rate value as the center and the heart rate resolution as the interval; wherein the heart rate value series records all possible target heart rate values ​​obtained after the current heart rate value is updated; the number of heart rate values ​​included in the heart rate value series is determined according to the maximum range of the heart rate change in the second time interval and the heart rate resolution;

[0162] Convert the heart rate value series into the frequency value series corresponding to the heart rate values.

[0163] So far, completed Figure 6 Description of the device for continuous detection of heart rate.

[0164] Correspondingly, in this embodiment, the embodiment of the present application also provides a computer-readable storage medium, on which a number of computer instructions are stored. When the computer instructions are executed, the method disclosed in the above example of the present application can be implemented.

[0165] Exemplarily, the computer-readable storage medium may be any electronic, magnetic, optical or other physical storage device that may contain or store information, such as executable instructions, data, etc. For example, the computer-readable storage medium may be: RAM (Radom Access Memory), volatile memory, non-volatile memory, flash memory, storage drive (such as hard disk drive), solid state drive, any type of storage disk (such as optical disk, DVD, etc.), or similar storage medium, or a combination thereof.

[0166] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for continuous heart rate detection, characterized in that: The method includes: Setting a cache queue, the cache queue is used to store the latest M data points in the reference photoplethysmography (PPG) signal obtained after preprocessing, where M is determined according to the sampling frequency of the reference PPG signal; In the case where M data points have been stored in the cache queue, at every first time interval, a reference heart rate value corresponding to the M data points is determined according to the latest M data points stored in the cache queue, until the absolute value of the difference between any two adjacent reference heart rate values ​​in the continuous K reference heart rate values ​​is less than a preset threshold, then an initial heart rate value is determined according to the K reference heart rate values, where K is greater than 1; Taking the initial heart rate value as the current heart rate value, after a second time interval, determining a frequency value sequence corresponding to the current heart rate value according to the current heart rate value and a preset heart rate resolution; the frequency value sequence records all possible candidate frequency values ​​corresponding to the target heart rate value obtained after the current heart rate value is updated; For each candidate frequency value in the frequency value sequence, the latest M data points stored in the cache queue are fitted according to a preset fitting curve and the candidate frequency value; The candidate frequency value corresponding to the maximum fitting result is determined as the target frequency value; the target heart rate value is determined according to the target frequency value; and the current heart rate value is updated to the target heart rate value.

2. The method according to claim 1, characterized in that After updating the current heart rate value to the target heart rate value, the method further comprises: The target heart rate value is used as the current heart rate value, and the step of determining the frequency value series corresponding to the current heart rate value according to the current heart rate value and the preset heart rate resolution after the second time interval has passed is returned until an instruction to stop heart rate detection is received.

3. The method according to claim 1, characterized in that The reference photoplethysmogram (PPG) signal is obtained by: The obtained original acceleration sensor ACC signal and the original PPG signal are filtered by the configured filter to obtain a candidate ACC signal and a candidate PPG signal; The candidate ACC signal is input into a configured adaptive filter to obtain a filter output signal, and the reference PPG signal is determined according to the candidate PPG signal and the filter output signal.

4. The method according to claim 1, characterized in that: The determining, according to the latest M data points stored in the cache queue, the reference heart rate values ​​corresponding to the M data points includes: Perform a fast Fourier transform (FFT) on the latest M data points stored in the cache queue to obtain a frequency spectrum corresponding to the M data points; The frequency value corresponding to the spectrum peak is determined according to the spectrum diagram, and the reference heart rate value is determined according to the frequency value corresponding to the spectrum peak.

5. The method according to claim 1, characterized in that: The determining the initial heart rate value according to the K reference heart rate values ​​comprises: Taking the last reference heart rate value among the K reference heart rate values ​​as the initial heart rate value; Alternatively, an average value of the K reference heart rate values ​​is used as the initial heart rate value.

6. The method according to claim 1, characterized in that The determining of the frequency value sequence corresponding to the current heart rate value according to the current heart rate value and the preset heart rate resolution includes: Generate a heart rate value series with the current heart rate value as the center and the heart rate resolution as the interval; wherein the heart rate value series records all possible target heart rate values ​​obtained after the current heart rate value is updated; the number of heart rate values ​​included in the heart rate value series is determined according to the maximum range of the heart rate change in the second time interval and the heart rate resolution; The heart rate value series is converted into a frequency value series corresponding to the heart rate values.

7. A heart rate continuous detection device, characterized in that: The device includes: A setting unit, used to set a cache queue, where the cache queue is used to store the latest M data points in the reference photoplethysmography (PPG) signal obtained after preprocessing, where M is determined according to a sampling frequency of the reference PPG signal; a determining unit, configured to determine, when M data points have been stored in the cache queue, reference heart rate values ​​corresponding to the M data points according to the latest M data points stored in the cache queue at every first time interval, until the absolute value of the difference between any two adjacent reference heart rate values ​​in K consecutive reference heart rate values ​​is less than a preset threshold, and then determine an initial heart rate value according to the K reference heart rate values, wherein K is greater than 1; Taking the initial heart rate value as the current heart rate value, after a second time interval, determining a frequency value sequence corresponding to the current heart rate value according to the current heart rate value and a preset heart rate resolution; the frequency value sequence records all possible candidate frequency values ​​corresponding to the target heart rate value obtained after the current heart rate value is updated; A fitting unit, for fitting, for each candidate frequency value in the frequency value series, the latest M data points stored in the cache queue according to a preset fitting curve and the candidate frequency value; An updating unit is used to determine the candidate frequency value corresponding to the maximum fitting result as the target frequency value; determine the target heart rate value according to the target frequency value; and update the current heart rate value to the target heart rate value.

8. The device according to claim 7, characterized in that After updating the current heart rate value to the target heart rate value, the updating unit is further used for: Taking the target heart rate value as the current heart rate value, returning to the step of determining the frequency value sequence corresponding to the current heart rate value according to the current heart rate value and a preset heart rate resolution after the second time interval has passed, until receiving an instruction to stop heart rate detection; And / or, the reference photoplethysmogram (PPG) signal is obtained by: The obtained original acceleration sensor ACC signal and the original PPG signal are filtered by the configured filter to obtain a candidate ACC signal and a candidate PPG signal; Input the candidate ACC signal into a configured adaptive filter to obtain a filter output signal, and determine the reference PPG signal according to the candidate PPG signal and the filter output signal; And / or, the determining unit is specifically configured to: Perform a fast Fourier transform (FFT) on the latest M data points stored in the cache queue to obtain a frequency spectrum corresponding to the M data points; Determine the frequency value corresponding to the spectrum peak according to the spectrum graph, and determine the reference heart rate value according to the frequency value corresponding to the spectrum peak; And / or, the determining unit is specifically configured to: Taking the last reference heart rate value among the K reference heart rate values ​​as the initial heart rate value; Alternatively, taking the average of the K reference heart rate values ​​as the initial heart rate value; And / or, the determining unit is specifically configured to: Generate a heart rate value series with the current heart rate value as the center and the heart rate resolution as the interval; wherein the heart rate value series records all possible target heart rate values ​​obtained after the current heart rate value is updated; the number of heart rate values ​​included in the heart rate value series is determined according to the maximum range of the heart rate change in the second time interval and the heart rate resolution; The heart rate value series is converted into a frequency value series corresponding to the heart rate values.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the method according to any one of claims 1 to 6 is implemented.

10. A computer-readable storage medium having a plurality of computer instructions stored thereon, characterized in that: When the computer instructions are executed, the method according to any one of claims 1 to 6 is implemented.

Images