Gas signal detection device, signal calibration synchronization method and filter selection method

Abstract

The invention discloses a gas signal detection device, a signal calibration synchronization method and a filter selection method, and the gas signal detection device comprises a sampling module which is used for collecting gas concentration; the signal calibration module is used for calibrating the gas concentration; and the signal processing module is used for filtering and synchronously processing the collected gas concentration to obtain the gas concentration meeting the detection requirement. According to the invention, the signal processing module is arranged to obtain the gas concentration after filtering and synchronous processing, when the gas concentration is subjected to data statistics, the concentration data meeting the response time requirement, namely the concentration data with shortened response time of the sampling module, can be effectively obtained, and the test precision is improved; meanwhile, through signal synchronous processing, time alignment of various output gas signals is achieved, effective data statistics is facilitated, and therefore the real heart and lung state of the tested person is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of respiratory gas detection, and in particular to a gas signal detection device, a signal calibration and synchronization method, and a filter selection method. Background Art

[0002] Cardiopulmonary exercise testing is a simultaneous assessment of the cardiovascular and respiratory responses to the same exercise stress by measuring gas exchange in the airways. Gas exchange refers to the process by which inhaled oxygen and exhaled carbon dioxide are exchanged in the body. The physiological process of breathing is the intake of oxygen from the outside air and the expulsion of carbon dioxide from the body.

[0003] During the cardiopulmonary exercise test, the respiratory gas passes through the flow sensor, is sampled by a specific device, passes through a dry pipeline, and the gas concentration is measured by the carbon dioxide concentration sensor and the oxygen concentration sensor. Each breath is then analyzed to obtain parameters such as oxygen uptake, carbon dioxide emissions, and respiratory exchange rate in the same period of time.

[0004] During the cardiopulmonary exercise test, the subject's breathing rate can reach more than 80 times / minute, and each exhalation lasts less than 300ms. The sensor response time is defined as the reaction time required for the concentration to change from 10% of the target concentration to 90% of the target concentration when the concentration of the gas to be detected changes. Currently, the response time of oxygen and carbon dioxide concentration sensors on the market varies greatly, and the general response time is around 300ms. When the breathing rate is high, the sensor response time is even higher than the exhalation time, which will seriously affect the test accuracy.

[0005] In addition, during cardiopulmonary exercise testing, the different installation locations and response times of carbon dioxide and oxygen concentration sensors result in differences in response times between sensors, making calculations and statistics inconvenient. Summary of the invention

[0006] The present invention discloses a gas signal detection device, a signal calibration synchronization method and a filter selection method to solve the problems in the prior art that the sensor response time is too high to affect the test accuracy and different sensors have different response times and cannot be aligned.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A gas signal detection device, comprising:

[0009] Sampling module, used to collect gas concentration;

[0010] Signal calibration module, used to calibrate gas concentration;

[0011] The signal processing module is used to filter and synchronously process the collected gas concentration to obtain the gas concentration that meets the detection requirements.

[0012] Furthermore, the filtering process uses a high-order FIR filter to process the gas concentration.

[0013] Furthermore, the order of the high-order FIR filter is 30-50.

[0014] Furthermore, the sampling module includes a sampling tube, a gas concentration sensor and a sampling pump which are sequentially connected through a first pipeline.

[0015] Furthermore, the gas concentration sensors include at least two types.

[0016] Furthermore, different gas concentration sensors are connected in series or in parallel.

[0017] Furthermore, the signal calibration module includes a gas cylinder, a gas valve and a flow limiting valve connected in sequence through a second pipeline; the end of the flow limiting valve away from the gas valve is connected to the sampling module through a three-way valve; and the three-way valve is connected to the atmosphere.

[0018] A filter selection method, wherein the filter is used to filter the gas concentration detected by the gas signal detection device, comprises the following steps:

[0019] Obtain calibrated gas concentrations at different time periods;

[0020] Send the calibrated gas concentration in the fluctuation stage to different filters for processing;

[0021] Get the response time of the gas concentration sensor after different filter processing;

[0022] A filter that meets the response time requirement is selected as the filter of the gas signal detection device.

[0023] Furthermore, the gas concentration in the fluctuation stage includes concentration data in a concentration increase and / or concentration decrease stage.

[0024] A gas concentration signal synchronization method is used to perform signal synchronization processing on the gas concentration detected by the gas signal detection device, comprising the following steps:

[0025] Get the signal time of different gas concentration sensors in corresponding states;

[0026] Calculate the delay time between different gas concentration sensors based on the signal time;

[0027] The signal time of the gas concentration sensor that responds in advance plus the delay time is taken as its final signal time, thus completing the signal synchronization processing.

[0028] A gas concentration signal calibration method is used to calibrate the gas concentration detected by the gas signal detection device, comprising the following steps:

[0029] Obtain a constant sampling flow rate;

[0030] The calibration gas concentration at different time periods output by the acquisition signal calibration module at a constant sampling flow rate;

[0031] The calibration coefficient of the calibration formula is calculated based on the calibration gas concentration at different time periods;

[0032] Substitute the calibration factor into the calibration formula to calibrate the gas concentration.

[0033] Furthermore, a constant sampling flow rate is obtained, including:

[0034] Obtain the response time of the gas concentration sensor at different sampling flow rates;

[0035] Get the sampling flow rate corresponding to the stable response time as the constant adopted flow rate.

[0036] Furthermore, the calibration formula is as follows:

[0037] y = a*x+b;

[0038] Wherein, y is the actual concentration, x is the concentration detected by the gas concentration sensor, a is the first calibration coefficient, and b is the value of the second calibration coefficient.

[0039] The present invention adopts the above technical solution and has the following advantages:

[0040] The present invention obtains the gas concentration after filtering and synchronization processing through the setting of the signal processing module. When performing data statistics on the gas concentration, it can effectively obtain concentration data that meets the response time requirement, that is, concentration data with shortened response time of the sampling module, thereby improving the test accuracy; at the same time, the present invention uses signal synchronization processing to align the time of various output gas signals, which is convenient for effective data statistics, thereby obtaining the true cardiopulmonary state of the subject; finally, the present invention also performs concentration calibration on the gas concentration signal collected by the sampling module, so that the output result of the entire detection device is more accurate, ensuring that the cardiopulmonary exercise test system can work stably and normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a connection diagram of the sampling module of the present invention;

[0042] Figure 2This is a connection diagram of the signal calibration module of the present invention;

[0043] Figure 3 This is a flow chart of the gas concentration signal calibration method of the present invention;

[0044] Figure 4 It is the response time curve under different sampling flow rates during calibration;

[0045] Figure 5 It is the relative concentration signal-time diagram at different times during the calibration process;

[0046] Figure 6 A flow chart of the filter selection method;

[0047] Figure 7 This is the response time diagram after processing by the second-order FIR filter;

[0048] Figure 8 This is the response time diagram after processing by 31-order FIR filter;

[0049] Fig. 9 This is the delayed time diagram of the carbon dioxide concentration sensor after filtering;

[0050] Fig.10 This is the delay time diagram of the oxygen concentration sensor after filtering;

[0051] Fig.11 This is a flow chart of the gas concentration signal synchronization method. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] A gas signal detection device comprises: a sampling module for collecting gas concentration; a signal calibration module for calibrating the gas concentration; and a signal processing module for filtering and synchronously processing the collected gas concentration to obtain a gas concentration that meets the detection requirements.

[0054] It can be understood that the present invention calibrates the gas concentration through the signal calibration module. Before sampling, the signal calibration module has completed the calibration of the sampling module, and the gas concentration output by the sampling module is the calibrated concentration. In other embodiments, the method of calibrating the gas concentration after collection can also be adopted.

[0055] The present invention obtains the gas concentration after filtering and synchronization processing through the setting of the signal processing module. When performing data statistics on the gas concentration, it can effectively obtain concentration data that meets the response time requirement, that is, concentration data with shortened response time of the sampling module, thereby improving the test accuracy; at the same time, the present invention uses signal synchronization processing to align the time of various output gas signals, which is convenient for effective data statistics, thereby obtaining the true cardiopulmonary state of the subject; finally, the present invention also performs concentration calibration on the gas concentration signal collected by the sampling module, so that the output result of the entire detection device is more accurate, ensuring that the cardiopulmonary exercise test system can work stably and normally.

[0056] like Figure 1 As shown, the sampling module includes a sampling tube, a gas concentration sensor and a sampling pump which are sequentially connected through a first pipeline; the gas concentration sensors include at least two types, and the gas concentration sensors in this embodiment are a carbon dioxide concentration sensor and an oxygen concentration sensor.

[0057] The sampling tube is used to collect respiratory gas. The respiratory gas flows through the carbon dioxide concentration sensor and the oxygen concentration sensor. The carbon dioxide concentration sensor and the oxygen concentration sensor respectively detect the carbon dioxide concentration and oxygen concentration in the respiratory gas to obtain the carbon dioxide concentration and oxygen concentration. The sampling pump is used to provide the different flow rates required during the sampling process.

[0058] Furthermore, the carbon dioxide concentration sensor and the oxygen concentration sensor are connected in series in which the carbon dioxide concentration sensor is placed before the oxygen concentration sensor. In other embodiments, the oxygen concentration sensor may be connected in series in which the carbon dioxide concentration sensor is placed before the carbon dioxide concentration sensor or the carbon dioxide concentration sensor and the oxygen concentration sensor may be connected in parallel.

[0059] Through the setting of the signal processing module, the present invention can make the signal response time of the above-mentioned sensor less than 100ms, meeting the analysis accuracy standard of daily cardiopulmonary exercise test. At the same time, concentration calibration and signal time alignment are also performed, so that the results of the cardiopulmonary exercise test can more accurately reflect the actual situation of the test subject.

[0060] In addition, in this embodiment, a pressure sensor for monitoring the gas line pressure is also provided on the first pipeline, and the pressure sensor can monitor the pipeline pressure in real time and judge the working state of the sampling pump. When the pressure sensor detects that the pipeline pressure is abnormal, the sampling pump can be automatically shut down to protect the pipeline and the sampling gas line and ensure the accuracy of the monitoring results.

[0061] The sampling tube is provided with a drying tube for balancing the humidity of the sampled air, so as to avoid the influence of the humidity of the breathing gas and the air on the test results during actual use.

[0062] like Figure 2As shown, the signal calibration module includes a gas cylinder, a gas valve and a flow limiting valve connected in sequence through a second pipeline; the end of the flow limiting valve away from the gas valve is connected to the sampling module through a three-way valve; the three-way valve is connected to the atmosphere.

[0063] During specific use, the flow limiting valve cooperates with the sampling pump to maintain a constant sampling flow, that is, to control the air pressure in the air pipeline to be relatively stable, to avoid drastic changes in pressure from having a significant impact on the test results, and to ensure the accuracy of the measurement results.

[0064] The gas composition in the gas cylinder is certain and different from the gas composition of the atmosphere. In this embodiment, a gas cylinder with an oxygen content of 15% and a carbon dioxide content of 6% is selected, while the oxygen content in the atmosphere is 21% and the carbon dioxide content is about 0%; the gas cylinder outputs positive pressure air to the sampling tube when the gas valve is opened, so that only the gas in the gas cylinder exists in the three-way pipe and the sampling tube; when the gas valve is closed, the gas cylinder no longer outputs gas, and the sampling pump in the sampling module will draw the atmosphere through the three-way pipe into the sampling tube for detection; the sampling pump draws sampling gas from the atmosphere or the gas cylinder at a constant flow rate; the gas valve is controlled to open and close at a preset time interval. For example, in this embodiment, the opening and closing interval is 4 seconds, that is, the gas valve is opened for 4 seconds and then closed for 4 seconds, and the opening and closing cycle is repeated.

[0065] Through the above method, the carbon dioxide concentration sensor and the oxygen concentration sensor obtain the gas concentrations in the atmosphere and the gas cylinder in different time periods; since the gas concentrations in the atmosphere and the gas cylinder are known, the calibration of the carbon dioxide concentration sensor and the oxygen concentration sensor can be completed through the concentration of the above known calibration gas and the sensor detection concentration.

[0066] like Figure 3 As shown, for the calibration of a carbon dioxide concentration sensor and an oxygen concentration sensor, the present invention discloses a gas concentration signal calibration method, comprising the following steps:

[0067] Obtain a constant sampling flow rate;

[0068] The calibration gas concentration at different time periods output by the acquisition signal calibration module at a constant sampling flow rate;

[0069] The calibration coefficient of the calibration formula is calculated based on the calibration gas concentration at different time periods;

[0070] Substitute the calibration factor into the calibration formula to calibrate the gas concentration.

[0071] Furthermore, a constant sampling flow rate is obtained, including:

[0072] Obtain the response time of the gas concentration sensor at different sampling flow rates;

[0073] The sampling flow rate corresponding to the stable response time is obtained as the constant sampling flow rate.

[0074] like Figure 4 As shown, the sampling pump works at different sampling flow rates, and the response time curves of the two sensors are measured. The horizontal axis in the figure is the sampling pump flow rate, and the vertical axis is the response time. It can be seen from the figure that when the sampling flow rate is 250mL / min, the sensor response time is not significantly changed compared to 200mL / min, and is within an acceptable range; in addition, when the flow rate is low, it is impossible to ensure that enough gas flows through the sensor, so the sensor response time will be extended; and when the flow rate is high, although the response time is not extended, it will lead to more sampling, and excessive flow will increase sensor consumption and affect the accuracy of flow data; in summary, in order to ensure that the sensor detection accuracy is high, over-current sampling is required, and the flow rate should not be too large, so this embodiment preferably uses 250mL / min as the sampling flow rate.

[0075] Furthermore, the calibration gas concentrations of different time periods output by the acquisition signal calibration module under a constant sampling flow rate include:

[0076] Set the valve opening and closing frequency to control the valve to open and close at a preset interval. For example, in this embodiment, the valve is opened and closed at an interval of 4 seconds, that is, the valve is opened for 4 seconds and then closed for 4 seconds. The calibration gas concentrations collected by the carbon dioxide concentration sensor and the oxygen concentration sensor at different time periods are as follows: Figure 5 shown.

[0077] Will Figure 5 Substitute the calibration gas concentration shown into the calibration formula to obtain the calibration coefficient of the calibration formula. The calibration formula is as follows:

[0078] y = a*x+b;

[0079] Among them, y is the actual concentration, and x is the concentration detected by the gas concentration sensor;

[0080] Substitute the calibration gas concentration Xn collected by the gas concentration sensor at different time periods, and the actual concentration Yn estimated at that moment based on the opening and closing conditions of the gas valve into the calibration formula to find the values ​​of the first calibration coefficient a and the second calibration coefficient b. Since the proportion of gas types in the gas cylinder and the atmosphere is relatively stable, it is convenient to directly correspond to the maximum or minimum value of the concentration signal of each gas concentration sensor. For example, in this embodiment, the maximum actual concentration of oxygen is 21% and the minimum is 15%; the maximum actual concentration of carbon dioxide is 6% and the minimum is 0%, which corresponds to the calibrated concentration of the gas concentration sensor at different time periods.

[0081] Since different gas concentration sensors have different calibration coefficients (a, b), the calibration coefficients of different gas concentration sensors need to be calculated separately. When calculating the calibration coefficient of one of the sensor concentration signals, multiple groups of signals at different times are taken. In this embodiment, the maximum and minimum concentration data of the gas concentration sensor in a certain time period are represented as X2 and X1, respectively. The actual maximum and minimum concentrations calculated according to time are represented as Y2 and Y1, respectively. Substituting the above expressions, we can get a=(Y2-Y1) / (X2-X1), b=Y1-a*X1.

[0082] The above is the coefficient value for one time period. To reduce the measurement error, in the same experiment, multiple data from different time periods are generally taken and the corresponding calibration coefficients (a1, b1), (a2, b2)... are calculated. Each group of calibration coefficients is substituted into y=a*x+b of each group of signals. The calibrated concentration value is calculated using the sensor signal concentration data as the independent variable. The calculated calibrated concentration value is compared with the actual concentration value estimated at that moment based on the opening and closing conditions of the gas valve, and the (a, b) corresponding to the minimum difference is comprehensively selected as the final calibration coefficient.

[0083] After the calibration coefficient is calculated by the above method, the coefficient can be used to perform concentration calibration during actual detection.

[0084] like Figure 6 As shown, the present invention also discloses a filter selection method for a gas signal detection device, comprising the following steps:

[0085] Obtain calibrated gas concentrations at different time periods;

[0086] Send the calibrated gas concentration in the fluctuation stage to different filters for processing;

[0087] Get the response time of the gas concentration sensor after different filter processing;

[0088] A filter that meets the response time requirement is selected as the filter of the gas signal detection device.

[0089] Furthermore, the gas concentration in the fluctuation stage includes concentration data in the concentration rising and / or concentration falling stages; the concentration data in the above stages are intercepted and sent to the filter, so that the filtered gas concentration can be obtained.

[0090] When intercepting the signal, determine whether the concentration data has been rising or falling for X consecutive concentration data since a certain moment. If so, this moment is the starting point of the concentration rise or fall; continue to determine the data along the starting point to determine whether the concentration data has not been rising or falling (including being flat) for X consecutive concentration data since a certain moment and is in a balanced state. This moment is the end point of the concentration rise or fall. The data between the start and end points is the data of the concentration rise or fall stage. The selection range of X here is generally 3 to 10, and the commonly used number is 5. That is, when determining the starting point, if 5 consecutive concentration data have been rising or falling since a certain moment, this moment is the starting point; when determining the end point of the rise, if 5 consecutive concentration data are all reduced or flat compared with the previous data, this moment is the end point of the rise; when determining the end point of the fall, if 5 consecutive concentration data are all increased or flat compared with the previous data, this moment is the end point of the fall.

[0091] The concentration data from the starting point to the end point of the above gas concentration change is sent to the filter for filtering calculation, such as Figure 7-8 shown.

[0092] Figure 7 This is the concentration signal diagram of the oxygen signal data after being processed by the second-order FIR filter. The dotted line and solid line represent the signal trends before and after filtering, respectively. It can be seen from the figure that the rising speed of the concentration signal processed by the second-order FIR filter is significantly faster, that is, the response time is significantly improved, but it drops rapidly after reaching the concentration peak and is close to the level before filtering, that is, the effect of the second-order FIR filter cannot cover the entire concentration rising stage. The curve that drops rapidly after reaching the concentration peak is easy to be analyzed as a concentration drop at this time during subsequent data analysis, but in fact the concentration at this stage should continue to rise.

[0093] Figure 8 This is the response time diagram of oxygen signal data after being processed by a 31-order FIR filter. The dotted line and solid line represent the signal trends before and after filtering, respectively. It can be seen from the figure that the rising speed of the concentration signal processed by the 31-order FIR filter is significantly faster. That is, after using the 31-order FIR filter, the response time is significantly improved, and after reaching the peak concentration, it does not drop significantly but fluctuates slightly and covers the entire concentration rising stage. Due to the small fluctuation amplitude, it is not easy to mistakenly analyze it as a concentration drop, and it can better represent the situation in the gas concentration rising stage.

[0094] The concentration data output by the filter is the filtered data after filtering. Due to the above filtering, the speed of concentration increase (or decrease) will inevitably be significantly accelerated, which is reflected in the concentration curve as the slope of the rising edge (or falling edge) of the concentration increases. Then, the time difference corresponding to 10% target concentration and 90% target concentration in the concentration will inevitably be reduced, that is, the response time is significantly shortened.

[0095] like Fig. 9 , 10 As shown, Fig. 9 This is the delay time diagram of the carbon dioxide concentration sensor after being processed by a 31-order filter. Fig.10 This is a time delay diagram of the oxygen concentration sensor after being processed by a 31-order filter. It can be seen from the figure that the response time after filtering is less than 100ms. Therefore, this embodiment uses a high-order FIR filter with an order of 31. In other embodiments, other order FIR filters with an order of 30-50 can also be used. The higher the order, the higher the computing power requirements of the signal processing module, and the smaller the fluctuation of the concentration curve after filtering after rising to the peak value. This embodiment selects the 31st order only as a balanced choice of computing power requirements and filtering effects, and does not limit the filter selection range of this application.

[0096] The filter in this embodiment uses a high-order FIR filter, and the filter itself performs iterative calculations on these concentration data. Since the filter and its iterative algorithm are both existing technologies, no further explanation is given here.

[0097] Due to the individual differences and positional differences of different sensors, there must be a certain delay in the signal times of different sensors. For example, when the signal of the oxygen concentration sensor is delayed than that of the carbon dioxide concentration sensor, the original signal is manifested as the rising point of the carbon dioxide concentration sensor concentration signal appearing earlier than the falling point of the oxygen concentration sensor concentration signal. To facilitate calculation and statistics, the signal processing module needs to align the two times when performing signal processing.

[0098] like Fig.11 As shown, it should be noted that, as mentioned above, this delay time comes from the individual differences and position differences of the sensors, so it is considered that the time difference is a constant value. Therefore, the following gas concentration signal synchronization method is adopted, including the following steps:

[0099] Get the signal time of different gas concentration sensors in corresponding states;

[0100] Calculate the delay time between different gas concentration sensors based on the signal time;

[0101] The signal time of the gas concentration sensor that responds in advance plus the delay time is taken as its final signal time, thus completing the signal synchronization processing.

[0102] Here, the time difference of different sensors in corresponding states is calculated, and then the time difference is extended to all concentration signals; the corresponding state means that in the actual detection process, due to the different changing states of different gas concentrations, for example, in the exhalation state, since the exhaled gas is basically carbon dioxide, at this time, in the detection process, the oxygen concentration detected by the oxygen concentration sensor should be in a decreasing state, and the corresponding carbon dioxide concentration detected by the carbon dioxide concentration sensor should be in an increasing state; but due to the difference in signal time detected by different sensors, the gas concentration state at the same time cannot correspond to the actual signal time diagram. In order to facilitate statistical calculations, signal synchronization processing is required.

[0103] To ensure that the states obtained from the two sensors correspond, the concentration change point with the closest signal time is generally selected as the corresponding state point. For example, during the calibration process, due to the different oxygen and carbon dioxide concentrations in the gas cylinder and the atmosphere, when the gas valve is continuously opened and closed, the concentration signals of the two sensors should change in opposite directions at the same time. That is, when the sensor oxygen signal begins to rise, the carbon dioxide concentration should begin to decrease. The time values ​​of the corresponding points of the two sensors, the oxygen rising point and the carbon dioxide falling point, are obtained, and the difference is calculated, and then the sensor with a later signal time can be aligned.

[0104] For example, first calculate the delay time ΔT between the oxygen concentration sensor and the carbon dioxide concentration sensor, ΔT = O 2 Concentration signal time-CO 2 Concentration signal time (in terms of 2 Taking sensor response time alignment as an example), after alignment, CO 2 Concentration signal time = CO in each state before alignment 2 The concentration signal time + ΔT, thereby achieving synchronization of the response time of the two sensors. The response time synchronization method of more sensors can be deduced in the same way, which will not be described in detail.

[0105] The above-mentioned device and method are described below through embodiments.

[0106] In this embodiment, CO 2 Sensor and O 2 There are three ways to connect two sensors, two of which are serial connections in reverse order, and the other is parallel connection. Therefore, the test is as follows: After completing the sampling gas path setting, control the sampling pump to sample at a flow rate of 270mL / min, connect the sensors in three ways, and obtain the following response times (Note: "front" in the table below means closer to the sampling tube):

[0107] Table 1 Comparison of sensor response time under different settings

[0108] Connection flow <![CDATA[CO 2 (s)]]> <![CDATA[O 2 (s)]]> <![CDATA[Serial: O 2 In CO 2 Before]]> 270mL / min 0.661 0.283 <![CDATA[Serial: CO 2 At O 2 Before]]> 270mL / min 0.203 0.303 parallel <![CDATA[CO 2 85mL / min;O 2 185mL / min]]> 0.242 0.309

[0109] It can be seen that when the carbon dioxide concentration sensor is before the oxygen concentration sensor, the response time is the shortest and the synchronization effect is better. 2 Sensor and O 2 The sensors are connected in series and the sampled air passes through the CO 2 Sensor and O 2 sensor.

[0110] The device of the present invention is mainly aimed at cardiopulmonary exercise test equipment. After actual application, the oxygen uptake (V O2 ), carbon dioxide emissions (V CO2 ) are 1 / 2 / 3 / 4 (L / min), and the corresponding respiratory rates (BF) are 20 / 40 / 60 / 80 (times / min). The device of the present invention is tested by a testing device, and the test results are as follows:

[0111] Table 2V O2 、V CO2 Actual measurement comparison table

[0112]

[0113] It can be seen from Table 2 that after the response time adjustment and delay synchronization, the measured values ​​are very close to the set values, which can meet the requirements of exercise cardiopulmonary test.

[0114] The present invention also discloses a cardiopulmonary exercise test system, including the respiratory gas signal detection device shown above, through which the oxygen and carbon dioxide gas concentration sensor signal response time is reduced and synchronously delayed, thereby obtaining accurate cardiopulmonary exercise test results.

[0115] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A gas signal detection device, characterized in that: include: Sampling module, used to collect gas concentration; Signal calibration module, used to calibrate gas concentration; The signal processing module is used to filter and synchronously process the collected gas concentration to obtain the gas concentration that meets the detection requirements.

2. A gas signal detection device according to claim 1, characterized in that: The filtering process uses a high-order FIR filter to process the gas concentration.

3. A gas signal detection device according to claim 2, characterized in that: The order of the high-order FIR filter is 30-50.

4. A gas signal detection device according to claim 1, characterized in that: The sampling module includes a sampling pipe, a gas concentration sensor and a sampling pump which are sequentially connected through a first pipeline.

5. A gas signal detection device according to claim 4, characterized in that: The gas concentration sensors include at least two types.

6. A gas signal detection device according to claim 5, characterized in that: Different gas concentration sensors are connected in series or in parallel.

7. A gas signal detection device according to claim 1, characterized in that: The signal calibration module includes a gas cylinder, a gas valve and a flow limiting valve which are sequentially connected through a second pipeline; one end of the flow limiting valve away from the gas valve is connected to the sampling module through a three-way valve; and the three-way valve is connected to the atmosphere.

8. A filter selection method, wherein the filter is used to filter the gas concentration detected by the gas signal detection device according to any one of claims 1 to 7, characterized in that: The following steps are involved: Obtain calibrated gas concentrations at different time periods; Send the calibrated gas concentration in the fluctuation stage to different filters for processing; Get the response time of the gas concentration sensor after different filter processing; A filter that meets the response time requirement is selected as the filter of the gas signal detection device.

9. A filter selection method according to claim 8, characterized in that: The gas concentration in the fluctuation stage includes concentration data in a concentration increase or / and concentration decrease stage.

10. A gas concentration signal synchronization method, used for performing signal synchronization processing on the gas concentration detected by the gas signal detection device according to any one of claims 1 to 7, characterized in that: The following steps are involved: Get the signal time of different gas concentration sensors in corresponding states; Calculate the delay time between different gas concentration sensors based on the signal time; The signal time of the gas concentration sensor that responds in advance plus the delay time is taken as its final signal time, thus completing the signal synchronization processing.

11. A gas concentration signal calibration method, used for calibrating the gas concentration detected by the gas signal detection device according to any one of claims 1 to 7, characterized in that: The following steps are involved: Obtain a constant sampling flow rate; The calibration gas concentration at different time periods output by the acquisition signal calibration module at a constant sampling flow rate; The calibration coefficient of the calibration formula is calculated based on the calibration gas concentration at different time periods; Substitute the calibration factor into the calibration formula to calibrate the gas concentration.

12. A gas concentration signal calibration method according to claim 11, characterized in that: Obtain a constant sampling flow, including: Obtain the response time of the gas concentration sensor at different sampling flow rates; Get the sampling flow rate corresponding to the stable response time as the constant adopted flow rate.

13. A gas concentration signal calibration method according to claim 11, characterized in that: The calibration formula is as follows: y=a*x+b; Wherein, y is the actual concentration, x is the concentration detected by the gas concentration sensor, a is the first calibration coefficient, and b is the value of the second calibration coefficient.

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