Breath judgment method based on Fourier transform, oxygen generator, controller and medium

Abstract

The invention discloses a breathing judgment method based on Fourier transform, an oxygenerator, a controller and a medium, and the method comprises the steps: collecting user breathing data, dynamically adjusting a breathing baseline, carrying out Fourier filtering processing, carrying out breathing judgment, and when new digital signal data is detected to be lower than a trigger threshold value, carrying out Fourier filtering processing on the breathing baseline; converting the acquired digital signal data into a frequency domain signal through Fourier transform, converting the frequency domain signal without a high-frequency signal into a time domain signal through inverse Fourier transform, constructing a time domain signal waveform by taking a breathing baseline as a reference, and judging a breathing action; the pulse type oxygen generator comprises an oxygen generation module, an oxygen outlet module and a judgment module. The breathing judgment method based on Fourier transform provided by the scheme is very simple and easy to implement, only needs simple steps and calculation, does not need any high-depth theoretical calculation, greatly improves the accuracy of breathing judgment, does not need to excessively depend on chip performance, and greatly reduces the cost of the pulse type oxygen generator.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a breathing determination method based on Fourier transform, an oxygen concentrator, a controller and a medium. Background Art

[0002] The pulse oxygen concentrator is based on the traditional oxygen concentrator. It detects the user's breathing by adding a breathing detection module, calculates the breathing frequency of this breath, and then controls the opening time of the oxygen outlet valve according to different breathing frequencies and different gears to achieve the control of the single output flow, thereby saving oxygen, improving oxygen utilization and improving oxygen inhalation comfort. It has the same oxygen supply effect as continuous oxygen supply, and the oxygen consumption of intermittent oxygen supply is only 1 / 6 of that of continuous oxygen supply. This also greatly reduces the size, weight and energy consumption of the oxygen concentrator and improves portability. It is generally composed of compressor components, adsorption tower components, reversing components, circuit control components, breathing detection components and other parts.

[0003] Since the pulse portable oxygen concentrator only outputs oxygen when the user inhales, reducing a large amount of ineffective oxygen output, judging the user's inhalation state is the basis for realizing this function. Most existing pulse oxygen concentrators detect the gas pressure in the gas transmission channel in real time, determine the amount of pressure change within a plurality of consecutive preset time periods according to the gas pressure, and judge the user's breathing state according to the change trend of the pressure change. In the process of realizing the present invention, the applicant has found that the existing breathing state judgment method of the pulse portable oxygen concentrator has at least the following problems:

[0004] 1. Due to the usage scenario of the portable oxygen concentrator, the nasal oxygen tube air path between the user and the device will often experience interference such as jitter, and the breathing detection and judgment method of the existing pulse portable oxygen concentrator has errors in judging the user's inhalation action.

[0005] 2. In the existing pulse portable oxygen concentrator, the transmitted electrical signal may be interfered by the circuit connection, which may lead to errors or large deviations in the detected data, and further errors in the judgment of the user's inhalation action.

[0006] 3. In addition, the breathing determination method used in the existing pulse portable oxygen concentrator has a relatively large amount of calculation and needs to rely on a high-cost chip to complete, which has a negative impact on the cost control of the pulse portable oxygen concentrator.

[0007] In view of this, how to develop a method and related technology that can stably, accurately and low-costly determine the user's inhalation action has become a topic to be studied and solved by the present invention. Summary of the invention

[0008] The purpose of the present invention is to provide a breathing determination method based on Fourier transform, an oxygen concentrator, a controller and a medium that can stably, accurately and at low cost determine the user's inhalation action.

[0009] To achieve the above object, the first aspect of the present invention proposes a breathing determination method based on Fourier transform, which is used for determining the breathing action of a pulse oxygen concentrator. The innovation of the method is that the method comprises:

[0010] Collect user breathing data and digital signal data of pressure changes when the user breathes using an oxygen concentrator.

[0011] Fourier filtering is performed. When it is detected that the new digital signal data is lower than the trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, and the high-frequency signal is removed from the frequency domain signal. Then, the frequency domain signal after removing the high-frequency signal is converted into a time domain signal through inverse Fourier transform.

[0012] Dynamically adjust the breathing baseline, obtain digital signal data within the most recent set time, perform Fourier transform on the obtained data and obtain DC component data, and dynamically adjust the DC component data to convert it into the breathing baseline for current breathing judgment.

[0013] Perform breathing judgment, construct a time domain signal waveform based on the breathing baseline, and divide the analysis window within the time domain signal waveform according to the time domain signal data after Fourier filtering, and judge whether the difference between the maximum and minimum values ​​in the time domain signal data exceeds the breathing threshold and whether the minimum value is located on the right side of the analysis window. If both are true, it is judged as a breathing action.

[0014] The second aspect of the present invention provides a pulse oxygen concentrator, which adopts the breathing determination based on Fourier transform in the method described in the first aspect. The innovation point is that the pulse oxygen concentrator includes an oxygen production module, an oxygen output module, and a determination module; wherein:

[0015] An oxygen production module, used to compress and separate oxygen from the air and store the oxygen, the oxygen production module comprising an oxygen production unit and a gas storage tank;

[0016] The oxygen outlet module is used to output the oxygen separated by the oxygen production module to the user. The oxygen outlet module includes an outlet valve, an oxygen outlet, a differential pressure sensor, and a nasal oxygen cannula. The differential pressure sensor collects digital signal data of pressure changes when the user breathes using the oxygen concentrator;

[0017] A determination module, after the pulse oxygen concentrator is started and operated, the determination module obtains digital signal data within the most recent set time, performs Fourier transform on the obtained data and obtains DC component data, and dynamically adjusts the DC component data to convert it into a respiratory baseline for current respiratory determination. When it is detected that the new digital signal data is lower than the set trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, the high-frequency signal is removed from the frequency domain signal, and then the frequency domain signal after the high-frequency signal is removed is converted into a time domain signal through inverse Fourier transform, a time domain signal waveform is constructed based on the respiratory baseline, and an analysis window is divided in the time domain signal waveform according to the time domain signal data after Fourier filtering, and it is determined whether the difference between the maximum value and the minimum value in the time domain signal data exceeds the respiratory threshold and whether the minimum value is located on the right side of the analysis window. If both are yes, it is determined to be a respiratory action.

[0018] A third aspect of the present invention provides a controller, which includes a memory, a processor, and a control program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in the first aspect when executing the control program.

[0019] A fourth aspect of the present invention proposes a control-readable storage medium, on which a control program is stored. When the control program is executed by a processor, the processor executes the steps of the method described in the first aspect.

[0020] The relevant contents of the present invention are explained as follows:

[0021] 1. Through the implementation of the above technical solutions of the present invention, in order to solve the problems of large errors caused by jitter and signal interference in the respiratory state judgment of the existing pulse portable oxygen concentrator, and high chip cost caused by large amount of calculation, a respiratory judgment method based on Fourier transform, a pulse oxygen concentrator, a controller and a control readable storage medium are innovatively designed. In the respiratory judgment method based on Fourier transform, the data used is digital signal data, which can avoid signal interference and errors caused by circuit wiring, thereby providing an accurate and reliable data basis for subsequent data processing and respiratory judgment; before performing respiratory judgment, a dynamic adjustment of the respiratory baseline is adopted, which can be dynamically adjusted according to the currently collected data, and the calculation method of the dynamic baseline is consistent with the calculation method used for judging the respiratory state, only the amount of data involved in the calculation is different from the value of the result, thereby reducing the amount of algorithm; because the respiratory signal is close to a sine wave, and most of the interference signals are high-frequency signals, when performing During the Fourier filtering process, when it is detected that the new digital signal data is lower than the trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, and the high-frequency signal is removed from the frequency domain signal. Then, the frequency domain signal after removing the high-frequency signal is converted into a time domain signal through inverse Fourier transform. This design is used to remove interference factors such as jitter that often occurs in the nasal oxygen tube airway between the user and the device, thereby reducing misjudgment caused by high-frequency interference signals. When making a breathing judgment, a time domain signal waveform is constructed based on the breathing baseline, so that the subsequent construction of the time domain signal waveform can be adaptively adjusted according to different usage scenarios and different usage states of the user, so that the different breathing changes generated by the user in different usage scenarios and different usage states can be matched with high precision, ensuring that the breathing judgment is more accurate, and dividing the analysis window in the time domain signal waveform according to the time domain signal data after Fourier filtering, making the breathing judgment process faster and simpler. The breathing determination method based on Fourier transform proposed in the present invention is also very simple and easy to implement. It only requires simple steps and calculations without any advanced theoretical calculations. It greatly improves the accuracy of breathing determination and does not need to rely too much on chip performance, which greatly reduces the cost of the pulse oxygen concentrator.

[0022] 2. In the first aspect of the above technical solution, in the step of collecting the user's breathing data, the differential pressure sensor is arranged at the oxygen outlet of the oxygen concentrator, and the differential pressure sensor is connected to the external atmospheric environment, and the oxygen outlet is connected to the nasal oxygen cannula. After the user inhales oxygen through the nasal oxygen cannula, obvious and regular pressure changes occur. The differential pressure sensor detects the pressure value in the nasal oxygen cannula in real time, and the pressure sensor collects digital signals as output digital signal data. In this way, signal interference and errors caused by circuit wiring are further avoided, thereby providing a more accurate and reliable data basis for subsequent data processing and breathing judgment.

[0023] 3. In the first aspect of the above technical solution, in the step of dynamically adjusting the breathing baseline, the digital signal data collected within the most recent set time is obtained, the obtained data is Fourier transformed to obtain the frequency domain value, the DC component data is found in the frequency domain value, and the DC component data is dynamically adjusted to convert into the breathing baseline for the current breathing determination. In this way, a more adaptive dynamic adjustment is obtained in different user scenarios and different usage states, ensuring more accurate breathing determination.

[0024] 4. In the first aspect of the above technical solution, in the step of performing Fourier filtering, the trigger threshold is set as a value for triggering the oxygen concentrator outlet point, which is a negative sensor data value of the respiratory baseline, so as to evaluate the sensitivity of the storage device triggering by generating a ramp-up sub-atmospheric pressure of 0.5 cmH2O per second on the nasal oxygen cannula. More specifically, the trigger pressure value of the trigger threshold can be set to 0.3 cmH2O.

[0025] 5. In the first aspect of the above technical solution, in the steps of dynamically adjusting the respiratory baseline and performing Fourier filtering, a fast Fourier transform is used when performing Fourier transform. After fast Fourier transform of the digital signal data of the pressure change when the user uses the oxygen concentrator to breathe, the bilateral spectrum data obtained is symmetrical on the left and right. Only half of the data needs to be calculated, thereby further reducing the amount of calculation and making breathing judgment faster.

[0026] 6. In the first aspect of the above technical solution, in the step of performing breathing determination, the trigger threshold is taken as the minimum value, and the maximum value corresponding to the trigger threshold value in the analysis window is obtained, the difference between the maximum value and the minimum value is calculated, and 90% of the minimum difference is selected as the breathing threshold. Since the greater the user's breathing amplitude, the greater the difference, 90% of the minimum difference is used as the breathing threshold, and the breathing threshold is used as an important indicator for breathing determination, which can ensure that breathing determination will not be lost or omitted, thereby ensuring stable and reliable oxygen supply.

[0027] 7. In the second aspect of the above technical solution, the determination module is configured to perform the following method steps:

[0028] Collect user breathing data, collect digital signal data of pressure changes when the user breathes using an oxygen concentrator, place a differential pressure sensor at the oxygen outlet of the oxygen concentrator, and connect the differential pressure sensor to the external atmospheric environment. The oxygen outlet is connected to the nasal oxygen cannula. After the user inhales oxygen through the nasal oxygen cannula, obvious and regular pressure changes occur. The differential pressure sensor detects the pressure value in the nasal oxygen cannula in real time, and the pressure sensor collects digital signals as output digital signal data.

[0029] Dynamically adjust the respiratory baseline, obtain the digital signal data collected within the most recent set time, use fast Fourier transform to obtain the frequency domain value of the obtained data, find the DC component data in the frequency domain value, and dynamically adjust the DC component data to convert it into the respiratory baseline for current respiratory judgment.

[0030] Fourier filtering is performed. When it is detected that the new digital signal data is lower than the trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, the high-frequency signal is removed from the frequency domain signal, and then the frequency domain signal after the high-frequency signal is removed is converted into a time domain signal through inverse Fourier transform; the trigger threshold is set to a value used to trigger the oxygen concentrator outlet point, which is the sensor data value of the negative respiratory baseline.

[0031] Perform breathing judgment, construct a time domain signal waveform based on the breathing baseline, and divide the analysis window in the time domain signal waveform according to the time domain signal data after Fourier filtering, and judge whether the difference between the maximum and minimum values ​​in the time domain signal data exceeds the breathing threshold and whether the minimum value is located on the right side of the analysis window. If both are true, it is judged as a breathing action; take the trigger threshold as the minimum value, and obtain the maximum value corresponding to the trigger threshold in the analysis window, calculate the difference between the maximum and minimum values, and select 90% of the minimum difference as the breathing threshold.

[0032] 8. In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] 9. In the present invention, the orientation or position relationship indicated by the terms "center", "upper", "lower", "axial", "bottom", "inner", "outer", etc. is based on the orientation or position assembly relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0034] 10. In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0035] Due to the application of the above scheme, the present invention has the following advantages and effects compared with the prior art:

[0036] 1. In the technical solution of the present invention, in order to solve the problems existing in the respiratory state judgment of the existing pulse portable oxygen concentrator, such as large errors caused by jitter and signal interference, and high chip cost caused by large amount of calculation, a respiratory judgment method based on Fourier transform, a pulse oxygen concentrator, a controller and a control readable storage medium are innovatively designed. In the respiratory judgment method based on Fourier transform, the data used is digital signal data, which can avoid signal interference and errors caused by circuit connection, thereby providing an accurate and reliable data basis for subsequent data processing and respiratory judgment.

[0037] 2. In the technical solution of the present invention, a dynamic adjustment of the breathing baseline is adopted before performing breathing judgment. It can be dynamically adjusted according to the currently collected data, and the calculation method of the dynamic baseline is consistent with the calculation method used for judging breathing. Only the amount of data participating in the calculation is different from the value of the result, thereby reducing the amount of algorithm. Since the breathing signal is close to a sine wave, and most of the interference signals are high-frequency signals, during the Fourier filtering process, when it is detected that the new digital signal data is lower than the trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, and the high-frequency signal is removed from the frequency domain signal. Then, the frequency domain signal after removing the high-frequency signal is converted into a time domain signal through inverse Fourier transform. This design can remove interference factors such as jitter that often occur in the nasal oxygen tube air path between the user and the device, thereby reducing misjudgment caused by high-frequency interference signals.

[0038] 3. In the technical solution of the present invention, when performing breathing judgment, a time domain signal waveform is constructed based on the breathing baseline, so that the construction of the subsequent time domain signal waveform can be adaptively adjusted according to different usage scenarios and different usage states of the user, so that the different breathing changes generated by the user in different usage scenarios and different usage states can be matched with high precision, ensuring that the breathing judgment is more accurate, and dividing the analysis window in the time domain signal waveform according to the time domain signal data after Fourier filtering, making the breathing judgment process faster and simpler.

[0039] 4. In summary, the breathing determination method based on Fourier transform proposed in the present invention is also very simple and easy to implement. It only requires simple steps and calculations without any advanced theoretical calculations. It greatly improves the accuracy of breathing determination and does not need to rely too much on chip performance, which greatly reduces the cost of the pulse oxygen concentrator. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the flow of the breathing determination method in an embodiment of the present invention;

[0041] Figure 2 is a detailed process flow chart of the breathing determination method in an embodiment of the present invention;

[0042] Figure 3 Schematic diagram of the waveform of the respiratory baseline in an embodiment of the present invention;

[0043] Figure 4A and Figure 4B It is a schematic diagram of the respiratory difference under different respiratory amplitudes;

[0044] Figure 5 is a butterfly operation graph in an embodiment of the present invention;

[0045] Figure 6 Schematic diagram of the installation position of the differential pressure sensor in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0047] Embodiment 1, as Figure 1 As shown, in the first embodiment of the present invention, a breathing determination method based on Fourier transform is proposed, which is used for the breathing action determination of the pulse oxygen concentrator. The method includes collecting user breathing data, dynamically adjusting the breathing baseline, performing Fourier filtering, and performing breathing determination:

[0048] Collect user breathing data and digital signal data of pressure changes when the user breathes using an oxygen concentrator.

[0049] Fourier filtering is performed. When it is detected that the new digital signal data is lower than the trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, and the high-frequency signal is removed from the frequency domain signal. Then, the frequency domain signal after removing the high-frequency signal is converted into a time domain signal through inverse Fourier transform.

[0050] Dynamically adjust the breathing baseline, obtain digital signal data within the most recent set time, perform Fourier transform on the obtained data and obtain DC component data, and dynamically adjust the DC component data to convert it into the breathing baseline for current breathing judgment.

[0051] Perform breathing judgment, construct a time domain signal waveform based on the breathing baseline, and divide the analysis window within the time domain signal waveform according to the time domain signal data after Fourier filtering, and judge whether the difference between the maximum and minimum values ​​in the time domain signal data exceeds the breathing threshold and whether the minimum value is located on the right side of the analysis window. If both are true, it is judged as a breathing action.

[0052] Through the implementation of the first embodiment of the present invention, in the breathing determination method based on Fourier transform, the data used is digital signal data, which can avoid signal interference and errors caused by circuit connections, thereby providing an accurate and reliable data basis for subsequent data processing and breathing determination; before performing breathing determination, a dynamic adjustment of the breathing baseline is adopted, which can be dynamically adjusted according to the currently collected data, and the calculation method of the dynamic baseline is consistent with the calculation method used for judging breathing, only the amount of data participating in the calculation is different from the value of the result, thereby reducing the amount of algorithm; because the breathing signal is close to a sine wave, and most of the interference signals are high-frequency signals, during the Fourier filtering process, when it is detected that the new digital signal data is lower than the trigger threshold, the collected digital signal data is first converted through Fourier transform. The high-frequency signal is removed from the frequency domain signal, and then the frequency domain signal after the high-frequency signal is removed is converted into a time domain signal through inverse Fourier transform. This design can remove interference factors such as jitter that often occurs in the nasal oxygen tube airway between the user and the device, and reduce misjudgment caused by high-frequency interference signals. When making a breathing judgment, the time domain signal waveform is constructed based on the breathing baseline, so that the subsequent construction of the time domain signal waveform can be adaptively adjusted according to different usage scenarios and different usage states of the user, so that the different breathing changes generated by the user in different usage scenarios and different usage states can be matched with high precision, ensuring that the breathing judgment is more accurate, and dividing the analysis window in the time domain signal waveform according to the time domain signal data after Fourier filtering, making the breathing judgment process faster and simpler.

[0053] In the above-mentioned embodiment 1, in the step of collecting the user's breathing data, the differential pressure sensor is arranged at the oxygen outlet of the oxygen concentrator, and the differential pressure sensor is connected to the external atmospheric environment, and the oxygen outlet is connected to the nasal oxygen cannula. After the user inhales oxygen through the nasal oxygen cannula, obvious and regular pressure changes are generated. The differential pressure sensor detects the pressure value in the nasal oxygen cannula in real time, and the pressure sensor collects digital signals as output digital signal data. In this way, signal interference and errors caused by circuit wiring are further avoided, thereby providing a more accurate and reliable data basis for subsequent data processing and breathing judgment.

[0054] In the above-mentioned embodiment 1, in the step of dynamically adjusting the breathing baseline, the digital signal data collected within the most recent set time is obtained, the obtained data is Fourier transformed to obtain the frequency domain value, the DC component data is found in the frequency domain value, and the DC component data is dynamically adjusted to convert into the breathing baseline for the current breathing determination. In this way, a more dynamic adjustment that is more adaptive to different user usage scenarios and different usage states is obtained to ensure that the breathing determination is more accurate. The generated breathing baseline can be referenced Figure 3 As shown, the sliding window of the adaptive baseline is 256 points, i.e. 2.56s, which can basically include most of the waveforms. After Fourier transform, the DC component is taken, i.e. the current respiratory baseline value.

[0055] In the above-mentioned embodiment 1, in the step of performing Fourier filtering, the trigger threshold is set as a value for triggering the oxygen concentrator outlet point, which is a negative sensor data value of the respiratory baseline, so as to evaluate the sensitivity of the storage device triggering by generating a ramp-up sub-atmospheric pressure of 0.5 cmH2O per second on the nasal oxygen tube. More specifically, the trigger pressure value of the trigger threshold can be set to 0.3 cmH2O.

[0056] In the above-mentioned first embodiment, in the steps of dynamically adjusting the respiratory baseline and performing Fourier filtering, fast Fourier transform is used when performing Fourier transform. After fast Fourier transform of the digital signal data of the pressure change when the user breathes using the oxygen concentrator, the bilateral spectrum data obtained is symmetrical on the left and right, and only half of the data needs to be calculated, thereby further reducing the amount of calculation and performing breathing judgment more quickly.

[0057] In the step of collecting user breathing data, taking the actual sampling of 10ms (ie 100HZ) and the number of processing points of 64 points as an example, the data of the bilateral spectrum obtained after Fourier transform is symmetrical on the left and right, so only half of the value is taken. That is, 32 data. The corresponding frequency is 100 / 64=1.5625. That is, the frequency corresponding to the first data is 1.5625HZ, and the frequency corresponding to the second data is 1.5625*2=3.125HZ, and the same applies to the rest. Since the normal breathing frequency is 15-40 times per minute, that is, 0.25-0.67HZ, only the first data is retained.

[0058] In the above-mentioned embodiment 1, in the step of performing breathing determination, the trigger threshold is taken as the minimum value, and the maximum value corresponding to the trigger threshold in the analysis window is obtained, the breathing difference between the maximum value and the minimum value is calculated, and 90% of the minimum breathing difference is selected as the breathing threshold. Figure 4A and Figure 4B As shown, since the greater the user's breathing amplitude, the greater the breathing difference, 90% of the minimum breathing difference is used as the breathing threshold, and the breathing threshold is used as an important indicator for breathing judgment, which can ensure that the breathing judgment will not be lost or omitted due to too small breathing amplitude, thereby ensuring stable and reliable oxygen supply.

[0059] Specifically, in the breathing determination method based on Fourier transform of the present invention, since the pressure in the nasal oxygen tube will change significantly and regularly when the user breathes, the obtained breathing signal is close to a sine wave, and the time domain signal after inverse Fourier transform is a sine wave. For example, the breathing waveform function is:

[0060] W(i)=100sin(2i);

[0061] The formula for adding interference signal is:

[0062] S(i)=W(i)+Z(i);

[0063] Where S(i) is the breathing signal with interference signal, W(i) is the breathing signal without interference, and Z(i) is the interference signal.

[0064] When calculating, this case takes the most recent 128 points as input.

[0065] That is, i=0,1,2...127;

[0066] After Fourier transformation of S(i) as the input signal, the spectrum data of the respiratory signal carrying noise can be obtained, which can be expressed as:

[0067] P(i),i=0,1,2,3.....127;

[0068] Where i represents frequency, and P(i) represents the spectral component of the signal at frequency i.

[0069] Assume that the signal sampling frequency is 1000HZ, and 128 points are sampled for data processing;

[0070] Since the data after Fourier transformation is symmetrical, only half of it is actually valid data, so we mainly focus on i=0,1...64

[0071] The frequency represented by i in P(i) is i*(1000 / 128). That is, when i=1, P(1) represents the spectrum component at a frequency of 7.8125 Hz.

[0072] Filtering is performed in the frequency domain, and the spectral components are directly set to 0 in the frequency domain, that is, P(i) = 0;

[0073] After filtering, the frequency domain signal needs to be restored to the time domain signal, that is, inverse Fourier transform. That is, P(i)i=0,1,....127 is taken as input, and F(i),i=1,2.....127 is output, which is the filtered time domain signal.

[0074] In the steps of dynamically adjusting the respiratory baseline and performing Fourier filtering, based on the sampling and calculation at the same time, a fast Fourier transform (FFT) is used for the Fourier transform and the inverse transform;

[0075] The formula for the Fast Fourier Transform (FFT) is as follows:

[0076]

[0077] Where:

[0078] N: The number of points involved in calculating the fast Fourier transform, usually 2 to the power of n;

[0079] a: data involved in the calculation;

[0080] a 2n : Even-numbered items in the data to be calculated;

[0081] a 2n+1 : Odd-numbered items in the data involved in the calculation;

[0082] W N : The rotation factor is calculated as

[0083] F K : Discrete Fourier transform result of even-numbered data;

[0084] G K : Discrete Fourier transform result of odd-numbered data;

[0085] A: The result data after calculation.

[0086] References Figure 5 In the butterfly operation diagram shown, since the value after Fourier transformation is a bilateral spectrum, that is, the data is symmetrical on the left and right, only half of the data needs to be calculated in the actual calculation value, further reducing the amount of calculation.

[0087] Embodiment 2. Embodiment 2 of the present invention discloses a pulse oxygen concentrator, which adopts the breathing determination based on Fourier transform in the method described in Embodiment 1 of the present invention. The innovation point is that the pulse oxygen concentrator includes an oxygen production module, an oxygen output module, and a determination module; wherein:

[0088] The oxygen production module is used to compress and separate oxygen from the air and store the oxygen. The oxygen production module includes an oxygen production unit and a gas storage tank.

[0089] The oxygen outlet module is used to output the oxygen separated by the oxygen generator module to the user. The oxygen outlet module includes an outlet valve, an oxygen outlet, a differential pressure sensor, and a nasal oxygen cannula. The differential pressure sensor collects digital signal data of pressure changes when the user breathes using the oxygen generator. The installation location of the differential pressure sensor can refer to Figure 6 shown.

[0090] A determination module, after the pulse oxygen concentrator is started and operated, the determination module obtains digital signal data within the most recent set time, performs Fourier transform on the obtained data and obtains DC component data, and dynamically adjusts the DC component data to convert it into a respiratory baseline for current respiratory determination. When it is detected that the new digital signal data is lower than the set trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, the high-frequency signal is removed from the frequency domain signal, and then the frequency domain signal after the high-frequency signal is removed is converted into a time domain signal through inverse Fourier transform, a time domain signal waveform is constructed based on the respiratory baseline, and an analysis window is divided in the time domain signal waveform according to the time domain signal data after Fourier filtering, and it is determined whether the difference between the maximum value and the minimum value in the time domain signal data exceeds the respiratory threshold and whether the minimum value is located on the right side of the analysis window. If both are yes, it is determined to be a respiratory action.

[0091] In the second embodiment of the present invention, the determination module is configured to perform the following steps: Figure 2 The specific steps shown are:

[0092] Collect user breathing data, collect digital signal data of pressure changes when the user breathes using an oxygen concentrator, place a differential pressure sensor at the oxygen outlet of the oxygen concentrator, and connect the differential pressure sensor to the external atmospheric environment. The oxygen outlet is connected to the nasal oxygen cannula. After the user inhales oxygen through the nasal oxygen cannula, obvious and regular pressure changes occur. The differential pressure sensor detects the pressure value in the nasal oxygen cannula in real time, and the pressure sensor collects digital signals as output digital signal data.

[0093] Dynamically adjust the respiratory baseline, obtain the digital signal data collected within the most recent set time, use fast Fourier transform to obtain the frequency domain value of the obtained data, find the DC component data in the frequency domain value, and dynamically adjust the DC component data to convert it into the respiratory baseline for current respiratory judgment.

[0094] Fourier filtering is performed. When it is detected that the new digital signal data is lower than the trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, the high-frequency signal is removed from the frequency domain signal, and then the frequency domain signal after the high-frequency signal is removed is converted into a time domain signal through inverse Fourier transform; the trigger threshold is set to a value used to trigger the oxygen concentrator outlet point, which is the sensor data value of the negative respiratory baseline.

[0095] Perform breathing judgment, construct a time domain signal waveform based on the breathing baseline, and divide the analysis window in the time domain signal waveform according to the time domain signal data after Fourier filtering, and judge whether the difference between the maximum and minimum values ​​in the time domain signal data exceeds the breathing threshold and whether the minimum value is located on the right side of the analysis window. If both are true, it is judged as a breathing action; take the trigger threshold as the minimum value, and obtain the maximum value corresponding to the trigger threshold in the analysis window, calculate the difference between the maximum and minimum values, and select 90% of the minimum difference as the breathing threshold.

[0096] Embodiment 3: Embodiment 3 of the present invention discloses a controller, including a memory, a processor, and a control program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in Embodiment 1 when executing the control program.

[0097] Embodiment 4: Embodiment 4 of the present invention further discloses a control-readable storage medium, on which a control program is stored. When the control program is executed by a processor, the processor executes the steps of the method described in Embodiment 1.

[0098] In each embodiment of the present invention, the proposed breathing determination method based on Fourier transform is also very simple and easy to implement. It only requires simple steps and calculations without any advanced theoretical calculations. It greatly improves the accuracy of breathing determination and does not need to rely too much on chip performance. It greatly reduces the cost of the pulse oxygen concentrator and achieves the purpose of the present invention.

[0099] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A breathing determination method based on Fourier transform, used for determining the breathing action of a pulse oxygen concentrator, characterized in that: The method includes: Collect user breathing data, and collect digital signal data of pressure changes when the user breathes using an oxygen concentrator; Perform Fourier filtering. When it is detected that the new digital signal data is lower than the trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, and the high-frequency signal is removed from the frequency domain signal. Then, the frequency domain signal after the high-frequency signal is removed is converted into a time domain signal through inverse Fourier transform. Dynamically adjust the breathing baseline, obtain digital signal data within the most recent set time, perform Fourier transform on the obtained data and obtain DC component data, and dynamically adjust the DC component data to convert it into the breathing baseline for current breathing determination; Perform breathing judgment, construct a time domain signal waveform based on the breathing baseline, and divide the analysis window within the time domain signal waveform according to the time domain signal data after Fourier filtering, and judge whether the difference between the maximum and minimum values ​​in the time domain signal data exceeds the breathing threshold and whether the minimum value is located on the right side of the analysis window. If both are true, it is judged as a breathing action.

2. The breathing determination method based on Fourier transform according to claim 1, characterized in that: In the step of collecting the user's breathing data, the differential pressure sensor is arranged at the oxygen outlet of the oxygen concentrator, and the differential pressure sensor is connected to the external atmospheric environment. The oxygen outlet is connected to the nasal oxygen cannula. After the user inhales oxygen through the nasal oxygen cannula, obvious and regular pressure changes occur. The differential pressure sensor detects the pressure value in the nasal oxygen cannula in real time, and the pressure sensor collects a digital signal as output digital signal data.

3. The breathing determination method based on Fourier transform according to claim 1, characterized in that: In the step of dynamically adjusting the respiratory baseline, the digital signal data collected within the most recent set time is obtained, the obtained data is Fourier transformed to obtain frequency domain values, the DC component data is found in the frequency domain values, and the DC component data is dynamically adjusted to be converted into the respiratory baseline for current respiratory judgment.

4. The breathing determination method based on Fourier transform according to claim 1, characterized in that: In the step of performing Fourier filtering, the trigger threshold is set to a value for triggering the oxygen concentrator outlet point, which is a sensor data value of the respiratory baseline that is negative.

5. The breathing determination method based on Fourier transform according to claim 1, characterized in that: In the steps of dynamically adjusting the respiratory baseline and performing Fourier filtering, a fast Fourier transform is used when performing Fourier transform. After fast Fourier transform of the digital signal data of the pressure change when the user breathes using the oxygen concentrator, the bilateral spectrum data obtained is symmetrical on the left and right, and only half of the data needs to be calculated.

6. The breathing determination method based on Fourier transform according to claim 1, characterized in that: In the step of performing breathing determination, the trigger threshold is taken as the minimum value, and the maximum value corresponding to the trigger threshold in the analysis window is obtained, the difference between the maximum value and the minimum value is calculated, and 90% of the minimum difference is selected as the breathing threshold.

7. A pulse oxygen concentrator, characterized in that: The pulse oxygen concentrator includes an oxygen production module, an oxygen output module, and a determination module; wherein: An oxygen production module, used to compress and separate oxygen from the air and store the oxygen, the oxygen production module comprising an oxygen production unit and a gas storage tank; The oxygen outlet module is used to output the oxygen separated by the oxygen production module to the user. The oxygen outlet module includes an outlet valve, an oxygen outlet, a differential pressure sensor, and a nasal oxygen cannula. The differential pressure sensor collects digital signal data of pressure changes when the user breathes using the oxygen concentrator; A determination module, after the pulse oxygen concentrator is started and operated, the determination module obtains digital signal data within the most recent set time, performs Fourier transform on the obtained data and obtains DC component data, and dynamically adjusts the DC component data to convert it into a respiratory baseline for current respiratory determination. When it is detected that the new digital signal data is lower than the set trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, the high-frequency signal is removed from the frequency domain signal, and then the frequency domain signal after the high-frequency signal is removed is converted into a time domain signal through inverse Fourier transform, a time domain signal waveform is constructed based on the respiratory baseline, and an analysis window is divided in the time domain signal waveform according to the time domain signal data after Fourier filtering, and it is determined whether the difference between the maximum value and the minimum value in the time domain signal data exceeds the respiratory threshold and whether the minimum value is located on the right side of the analysis window. If both are yes, it is determined to be a respiratory action.

8. The pulse oxygen concentrator according to claim 7, characterized in that: The determination module is configured to perform the following method steps: Collect user breathing data, collect digital signal data of pressure changes when the user breathes using an oxygen concentrator, place a differential pressure sensor at the oxygen outlet of the oxygen concentrator, and connect the differential pressure sensor to the external atmospheric environment, and connect the oxygen outlet to the nasal oxygen cannula. After the user inhales oxygen through the nasal oxygen cannula, obvious and regular pressure changes occur. The differential pressure sensor detects the pressure value in the nasal oxygen cannula in real time, and the pressure sensor collects digital signals as output digital signal data; Dynamically adjust the respiratory baseline, obtain the digital signal data collected within the most recent set time, use fast Fourier transform to obtain the frequency domain value of the obtained data, find the DC component data in the frequency domain value, and dynamically adjust the DC component data to convert it into the respiratory baseline for current respiratory judgment; Perform Fourier filtering processing. When it is detected that the new digital signal data is lower than the trigger threshold, the collected digital signal data is first converted into a frequency domain signal through Fourier transform, the high-frequency signal is removed from the frequency domain signal, and then the frequency domain signal after the high-frequency signal is removed is converted into a time domain signal through inverse Fourier transform; the trigger threshold is set to a value for triggering the oxygen concentrator outlet point, which is the sensor data value of the respiratory baseline to the negative direction; Perform breathing judgment, construct a time domain signal waveform based on the breathing baseline, and divide the analysis window in the time domain signal waveform according to the time domain signal data after Fourier filtering, and judge whether the difference between the maximum and minimum values ​​in the time domain signal data exceeds the breathing threshold and whether the minimum value is located on the right side of the analysis window. If both are true, it is judged as a breathing action; take the trigger threshold as the minimum value, and obtain the maximum value corresponding to the trigger threshold in the analysis window, calculate the difference between the maximum and minimum values, and select 90% of the minimum difference as the breathing threshold.

9. A controller, characterized in that: The controller includes a memory, a processor, and a control program stored in the memory and executable on the processor. When the processor executes the control program, the steps of the method described in any one of claims 1 to 6 are implemented.

10. A control-readable storage medium, characterized in that: A control program is stored on the control readable storage medium. When the control program is executed by a processor, the processor executes the steps of the method according to any one of claims 1 to 6.

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