A heart rate calculation algorithm based on a heart sound autocorrelation function

A technology of autocorrelation function and calculation algorithm, applied in computing, computer parts, computer-aided medical procedures, etc., can solve the problems of false period value, high hardware cost, large amount of calculation of autocorrelation function, etc. volume reduction effect

Active Publication Date: 2019-04-16
FOSHAN BAIBUTI MEDICAL TECH CO LTD +1
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AI Technical Summary

Problems solved by technology

[0005] 1) Both the envelope and autocorrelation function will have abnormal peaks due to the interference of breath sounds, friction sounds and other factors, resulting in heart rate calculation errors; There is a friction sound; and when the breathing is rapid, this interference will be more significant;
[0006] 2) Some heart sounds have the first and second heart sounds at the same time. Since the waveforms of the first and second heart sounds are similar, if the traditional correlation analysis method is directly used to calculate the heart rate, it is easy to get false cycle values; The second heart sound can overcome the influence of this factor, but the boundary between the first and second heart sounds is not obvious for a considerable part of the heart sound, so it cannot be determined by removing the envelope peak or autocorrelation function peak caused by the second heart sound heart rate;
[0007] 3) The sampling time cannot be too long; generally speaking, the duration of auscultation is usually no more than half a minute, sometimes even shorter, so heart rate monitoring based on heart sound signals can only be estimated based on heart sound signals of several heartbeat cycles. The existing autocorrelation function has a huge amount of calculation. When the sampling frequency is high, in order to complete the calculation of the autocorrelation function in a short time, it is often necessary to equip hardware with strong computing power, resulting in high hardware costs.
[0008] Therefore, there are still many difficulties in using existing solutions and methods to estimate heart rate based on heart sounds

Method used

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  • A heart rate calculation algorithm based on a heart sound autocorrelation function
  • A heart rate calculation algorithm based on a heart sound autocorrelation function
  • A heart rate calculation algorithm based on a heart sound autocorrelation function

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Embodiment 1

[0053] This embodiment is based on the heart rate calculation algorithm of the heart sound autocorrelation function, and its workflow is as follows figure 1 shown, including the following steps:

[0054] In the first step, at the sampling frequency f s Obtain a heart sound sequence x(k) with a duration of t and a length of N, where k=1,...,N, N is a positive integer, N=tf s ; The value range of duration t is preferably: 2.5s

[0055] The second step is to filter the heart sound sequence x(k) to obtain the sequence Preferably, the cut-off frequency for the heart sound sequence x(k) is f c The low-pass filtering of cut-off frequency f c The preferred range of values ​​is: f c ∈[150, 250]Hz; the low-pass filter can adopt the existing low-pass filter method, preferably the second-order or above low-pass filter; it can also use other filter processing that can suppress the interference of breath sounds and friction sounds;

[0056] In the third step, the frequency ...

Embodiment 2

[0098] This embodiment is based on the heart rate calculation algorithm of the heart sound autocorrelation function, and its workflow is as follows Figure 4 As shown, the difference with Embodiment 1 is that in this embodiment, the fourth step is to shift the serial number The envelope En(m) is directly calculated by the autocorrelation function R(n) within the search range.

[0099] Specifically, it means: calculate the autocorrelation function R(n) of the envelope En(m):

[0100]

[0101] in,

[0102] The remaining steps of this embodiment are the same as those of Embodiment 1.

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Abstract

The invention provides a heart rate calculation algorithm based on a heart sound autocorrelation function, which is characterized by comprising the following steps: obtaining a heart sound sequence, and carrying out filtering processing and envelope solving on the heart sound sequence; And calculating an autocorrelation function in the search range, searching a peak point of the autocorrelation function, and calculating a heart rate value according to the serial number of the peak point. The calculation algorithm can overcome interference of factors such as respiratory sound, friction sound, first heart sound waveform similarity and second heart sound waveform similarity, the heart rate value can be accurately calculated through the heart sound sequence, the calculation algorithm can be conveniently achieved in small wearable equipment and small electronic stethoscopes, and the calculation algorithm is also suitable for electronic auscultation auxiliary diagnosis and treatment systemsfor hospitals and families.

Description

technical field [0001] The invention relates to the field of medical equipment and medical signal processing, more specifically, to a heart rate calculation algorithm based on heart sound autocorrelation function. Background technique [0002] Heart rate is one of the important indicators to reflect the health status of the body. Heart rate monitoring is of great significance for some patients with heart disease, such as medication and home care. [0003] With the popularity of telemedicine, electronic stethoscopes will enter more community hospitals and families, and remote auscultation of heart sounds will increasingly become one of the important means of many telemedicine projects, including home care for heart patients. Compared with common methods such as measuring heart rate based on pulse, calculating heart rate using heart sound signals has higher accuracy, is convenient to use, and is low in cost. Therefore, calculating heart rate based on heart sounds is bound to ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06K9/00G16H50/20G16H80/00
CPCG16H50/20G16H80/00G06F2218/04G06F2218/12
Inventor 莫鸿强田翔王伟丞
Owner FOSHAN BAIBUTI MEDICAL TECH CO LTD
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