CN113558659A - High-precision ultrasonic lung function detector and detection method thereof - Google Patents

High-precision ultrasonic lung function detector and detection method thereof Download PDF

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CN113558659A
CN113558659A CN202110868691.7A CN202110868691A CN113558659A CN 113558659 A CN113558659 A CN 113558659A CN 202110868691 A CN202110868691 A CN 202110868691A CN 113558659 A CN113558659 A CN 113558659A
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ultrasonic
time
flow
correction
velocity
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CN113558659B (en
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吴正相
王睿
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Chongqing Anku Technology Co ltd
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/44—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/58—Testing, adjusting or calibrating the diagnostic device
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D21/00—Measuring or testing not otherwise provided for
    • G01D21/02—Measuring two or more variables by means not covered by a single other subclass
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/667—Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
    • G01F1/668—Compensating or correcting for variations in velocity of sound
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K17/00—Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations
    • G06K17/0022—Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations arrangements or provisious for transferring data to distant stations, e.g. from a sensing device
    • G06K17/0029—Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations arrangements or provisious for transferring data to distant stations, e.g. from a sensing device the arrangement being specially adapted for wireless interrogation of grouped or bundled articles tagged with wireless record carriers
    • G—PHYSICS
    • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
    • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
    • G16H40/00—ICT specially adapted for the management or administration of healthcare resources or facilities; ICT specially adapted for the management or operation of medical equipment or devices
    • G16H40/60—ICT specially adapted for the management or administration of healthcare resources or facilities; ICT specially adapted for the management or operation of medical equipment or devices for the operation of medical equipment or devices
    • G16H40/67—ICT specially adapted for the management or administration of healthcare resources or facilities; ICT specially adapted for the management or operation of medical equipment or devices for the operation of medical equipment or devices for remote operation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/02—Operational features
    • A61B2560/0242—Operational features adapted to measure environmental factors, e.g. temperature, pollution
    • A61B2560/0247—Operational features adapted to measure environmental factors, e.g. temperature, pollution for compensation or correction of the measured physiological value
    • A61B2560/0252—Operational features adapted to measure environmental factors, e.g. temperature, pollution for compensation or correction of the measured physiological value using ambient temperature

Abstract

The invention discloses a high-precision ultrasonic pulmonary function detector and a detection method thereof, and the high-precision ultrasonic pulmonary function detector comprises a blow pipe and a plurality of nipples, wherein two ultrasonic sensors are arranged on the blow pipe, any one of the nipples can be movably arranged in the blow pipe in a penetrating manner, the ultrasonic sensors are connected with a change-over switch, the change-over switch is connected with an amplifying circuit and an amplitude change circuit, the two amplitude change circuits are connected with the same boosting circuit and the same pulse emission and precision time measurement chip, the amplifying circuit is connected with a band-pass filter circuit, the two band-pass filter circuits are both connected with the pulse emission and precision time measurement chip, the pulse emission and precision time measurement chip is in serial communication connection with a microcontroller, the microcontroller respectively controls the two change-over switches, the microcontroller is in communication connection with a server, and the server is electrically connected with an environmental parameter detector. The invention can measure the flow rate under the condition of completely not obstructing the respiration, has no pressure loss, extremely high sensitivity and wide range of measurement, and the respiratory flow can be obtained by integral calculation of the measured flow rate.

Description

High-precision ultrasonic lung function detector and detection method thereof
Technical Field
The invention relates to the technical field of medical detection, in particular to a high-precision ultrasonic lung function detector and a detection method thereof.
Background
With economic development, environmental pollution is becoming more severe, resulting in more and more people suffering from respiratory diseases. The lung function examination is one of necessary examinations of respiratory system diseases, and the lung function is measured by a lung function instrument, so that the purpose of detecting respiratory system abnormality is achieved. The kit has important guiding significance for early detection of lung and respiratory tract diseases, such as chronic bronchitis, emphysema, bronchial asthma, intermittent lung diseases and the like.
The ultrasonic gas flow measurement technology has the following advantages: (1) the precision is high; (2) no moving parts are needed, and the service life is reliable and long; (3) the flow measurement result is slightly influenced by environmental parameters such as gas components, pressure, temperature and humidity, and has good repeatability; (4) the stability is good, and the trouble of frequent calibration is avoided; (5) easy sterilization and avoiding cross infection. At present, the scheme of the ultrasonic lung function instrument is that two small ultrasonic sensors are arranged on the upstream and downstream of a blowing pipe, the core technology of the lung function instrument is the sensor technology, and the key point is a flow sensor. The instantaneous flow is measured by using the relationship between the propagation time difference of ultrasonic waves in forward flow and reverse flow and the gas flow, and various lung function indexes are obtained through a certain corresponding relationship. However, the application occasion of the ultrasonic lung function instrument is a blowpipe with a very small pipe diameter, so that the flow velocity of gas is very large under the condition of the same flow, ultrasonic signals are greatly attenuated and even submerged in noise, the measurement precision is greatly influenced, and the measurement range is limited.
Methods for measuring the gas flow rate by using ultrasonic waves can be roughly divided into four types: frequency difference method, correlation method, doppler method, and time difference method. The frequency difference method and the correlation method have low resolution and are difficult to realize, so that the practical application is less. The Doppler effect method is used for measuring the Doppler effect of frequency shift of ultrasonic waves due to reflection of suspended particles or bubbles existing in fluid in the transmission process, is mainly used for multiphase fluid with large magazine particles, and is suitable for fluid measurement with more impurities and uniform distribution. Because the measurement accuracy of the Doppler method is influenced by temperature change and scatterers, correction is needed, and the correction process is relatively complex, the actual application is less. Based on the consideration of two factors of difficulty and realizability, the gas ultrasonic flowmeter with the largest production and the widest application range is mainly realized by adopting a time difference method at present. The time difference method is used for measuring the propagation speed of ultrasonic waves in a fluid according to the principle that the propagation speed of the ultrasonic waves in the fluid changes along with the speed change of the fluid, the flow speed v is calculated by measuring the time difference delta t of forward and backward propagation of the ultrasonic waves, and then the flow can be calculated according to Q-s-v. The flowmeter is mainly applied to single-phase liquid and is suitable for industrial clean water measurement. Because the propagation efficiency of the ultrasonic wave in the gas is low, the signal attenuation is high, the frequency of the ultrasonic wave is high, the noise is large, the signal to noise ratio is difficult to improve, the pipe diameter of the pulmonary function instrument is very small, and the precision is difficult to improve.
And because the lung function instrument can be used repeatedly by patients at different time intervals in a day for detection, in the actual use process, because the detector is used irregularly, if different patients use the same mouthpiece tube for detection, cross infection can be caused, and the detection result is inaccurate.
Disclosure of Invention
In order to solve the technical problems, the invention provides a high-precision ultrasonic lung function detector which has no pressure loss and is wide in real-time range correction of the ultrasonic sound velocity and a detection method thereof.
The technical scheme adopted by the invention is as follows: the utility model provides a high accuracy ultrasonic wave lung function detector, includes the blowpipe and sets up two ultrasonic sensor on the blowpipe, the key lies in: the signal output ends of the two ultrasonic sensors are positioned in the blowpipe and are arranged opposite to each other, the ultrasonic sensors are connected with a selector switch, the change-over switch is connected with an amplifying circuit and amplitude changing circuits, the two amplitude changing circuits are connected with the same booster circuit and the same pulse transmitting and precise time measuring chip, the amplifying circuit is connected with band-pass filter circuits, both of which are connected with the pulse transmitting and precise time measuring chip, the pulse transmitting and precise time measuring chip is connected with a microcontroller in serial communication, the microcontroller respectively controls the two change-over switches, the microcontroller is in communication connection with the server, the server is electrically connected with the environmental parameter detector, and based on the hardware connection, the high-precision ultrasonic lung function detector can be realized by utilizing the mutual cooperation of a zero-crossing detection correction method and a real-time compensation correction method by matching with a program of the microcontroller.
Preferably, an included angle is formed between a connecting line of the two ultrasonic sensors and the blow pipe, and the included angle α is 0< α <90 °.
Preferably, the environment parameter detector comprises a temperature detection module, a humidity detection module and an air pressure detection module.
Preferably, a shielding case is installed outside the amplifying circuit and the band-pass filter circuit.
The effect of the above scheme is that the switch is used for switching the working state (transmitting/receiving) of the ultrasonic sensor, the transmitting, i.e. driving signal directly acts on the ultrasonic sensor, and the receiving, i.e. signal of the ultrasonic sensor is accessed into the amplifying circuit; the band-pass filter circuit is used for shielding interference signals outside the working frequency, and only signals in a certain frequency band are selected for measurement. A plurality of band-pass filter circuits can be connected in series in the circuit, so that the filtering effect is better; the amplifying circuit is used for amplifying signals of the ultrasonic sensor, and because the amplitude of the signals of the ultrasonic sensor is very small, threshold detection judgment is difficult to carry out, and the signals are amplified to be more beneficial to threshold detection and zero-crossing detection; the amplitude change circuit is used for increasing the amplitude of a transmitting signal of the signal generator, the power of the transmitting signal of the signal generator directly driving the ultrasonic sensor is too low, the amplitude is increased by controlling the grid driver or the high-speed driving circuit, and the ultrasonic transmitting power is increased; the booster circuit is used for providing stable voltage for the amplitude variation part; the pulse transmitting and precise time measuring chip is provided with a programmable pulse transmitting and precise time period counting chip/module which respectively measures the upstream and downstream flight time and is used for calculating the transit time difference so as to calculate the flow rate value; the environment parameter detector is used for detecting the real-time temperature and the real-time humidity of the environment, and the plurality of mouthpieces can be suitable for the patient conditions with different vital capacities to be selected, so that the detection accuracy rate is improved.
High-precision ultrasonic waveThe detection method of the lung function detector is characterized in that: the microcontroller sends a detection starting signal to the pulse transmitting and precise time measuring chip, the upstream ultrasonic sensor is switched to transmit, the downstream ultrasonic sensor is switched to receive, the pulse transmitting and precise time measuring chip starts to time and sends 2 continuous pulse signals, the amplitudes of the 2 pulse signals are increased through the booster circuit and the amplitude change circuit, and the pulse signals are added to the upstream ultrasonic sensor; the downstream ultrasonic sensor receives ultrasonic signals, the ultrasonic signals are processed by an amplifying circuit and a band-pass filter circuit and transmitted to a pulse emission and precise time measurement chip, the pulse emission and precise time measurement chip judges the end of timing according to a set threshold value and a zero crossing point, and the transit time t is calculatedup(ii) a Similarly, the ultrasonic sensor at the upstream is switched to receive the ultrasonic signal, the ultrasonic sensor at the downstream is switched to receive the ultrasonic signal, and the transit time t can be calculated through the same modedown(ii) a For the transit time t measured in the high and low flow velocity regionsupAnd tdownRespectively correcting by adopting a zero-crossing detection correction method, and calculating to obtain the volume flow VMeasuring(ii) a And simultaneously adopts a real-time compensation correction method to correct the volume flow VMeasuringReal-time environmental parameter correction is carried out to finally obtain the volume flow VBTPS。
Preferably, the zero-crossing detection correction method is: s1, threshold voltage is set in advance, when the amplitude of a received signal of the ultrasonic sensor reaches a threshold value, zero-crossing detection is started, a plurality of zero-crossing points can be set as timing end points, and transition time t can be obtainedupAnd tdownThrough tupAnd tdownCalculating a fluid flow velocity v; s2, because the ultrasonic wave is greatly propagated and attenuated in the high-flow-velocity gas medium, the preset threshold voltage does not detect the sound wave needing to be detected, namely the sound wave with the lead/lag period is detected, so that the transit time t is made to be longerupOr tdownThe deviations of t' and t "occur at the time points t1, t2 and t3, respectively, for three successive points a, b and c on the flow-time curve defining the breathing process, the corresponding flow rates v being respectively1，v2And v3，Δy1And Δ y2Flow speed difference of two successive points, i.e. Δ y1＝v2-v1，Δy2＝v3-v2Let m be the sum of absolute flow velocities of points a and b, i.e., m ═ v1|+|v2L for judging whether it is a low flow rate region or a high flow rate region, setting mmidIs a limit value when m<mmidWhen m is a low flow rate region>mmidIn the time, the abnormal flow velocity of the high flow velocity region is corrected by adopting different data correction algorithms respectively; s3. since the measured fluid flow velocity V is actually the linear average velocity on the inner diameter of the section of the pipeline, and the measured flow requires the surface average flow velocity V' of the section of the pipeline, the volume flow VMeasuringThen the calculation is carried out by using the formula (7),
Figure RE-GDA0003276943210000051
wherein t is1And t2To determine the time when the flow measurement starts and ends, D is the diameter of the pipe, v' ═ kv, and k is the reynolds number correction factor.
Preferably, in S1: t is tupCalculate using equation 1
Figure RE-GDA0003276943210000052
tdownCalculate using equation 2
Figure RE-GDA0003276943210000053
Wherein L is the sound channel length, c is the ultrasonic sound velocity, theta is the sound channel and pipeline axial included angle, v is the fluid velocity, and the cocurrent and countercurrent transit time difference Deltat adopts formula 3 to calculate:
Figure RE-GDA0003276943210000054
due to c2＞＞v2cos2θ, then Δ t can be simplified to equation 4:
Figure RE-GDA0003276943210000055
the flow velocity v is thus calculated using equation 5:
Figure RE-GDA0003276943210000056
preferably, in S2, the abnormal data in the low flow velocity region is filtered by mean filtering, and | Δ y is set2|maxThreshold value of abnormal flow velocity data in low flow velocity zone, i.e. | Deltay2|＞|Δy2|maxWhen the flow rate data is abnormal, the corrected flow rate is v3′＝(v1+v2) 2; the following filtering algorithm was used for the anomaly data in the high flow region:
let Δ y3＝|Δy1|+|Δy2|, Δ y can be obtained3Time curve, setting decision threshold Δ ymaxWhen Δ y3＞ΔymaxIf it is determined that the data is erroneous, data correction is necessary, and in this case, Δ y is set1>A positive cycle flow difference, the correction method is to subtract Δ t from one ultrasonic clock cycle, i.e., Δ t' ═ Δ t-1/f; if Δ y1<A negative cycle flow rate difference, the correction method is Δ t plus one ultrasonic clock cycle, i.e., Δ t ═ Δ t +1/f, and the flow rate values v 'and v "calculated using Δ t' and Δ t" are corrected flow rate values.
Preferably, the real-time compensation correction method is as follows: s1, judging whether the test state of a user is an inspiration process or an expiration process according to the formula (3); s2, sound velocity correction: respectively correcting the ultrasonic sound velocity c by adopting a sound velocity correction formula according to different test states; s3, real-time BTPS correction: for different test states, the volume flow V is respectively adjustedMeasuringCorrection by the formula (10), VBTPSCorrection factor x VMeasuring(10) Wherein the correction coefficient is calculated using a BTPS correction formula.
Preferably, the sound speed correction specifically includes: when delta T is greater than 0, the inspiration process is carried out, delta T is less than 0, the expiration process is carried out, the real-time temperature T measured by the environment parameter detector is adopted to calibrate the ultrasonic sound velocity c, and the expiration process is carried out by adopting the medical expiration temperature empirical value to calibrate the ultrasonic sound velocity c; the real-time BTPS correction specifically comprises the following steps: when delta T is more than 0, the inspiration process is carried out, delta T is less than 0, the expiration process is carried out, the volume flow V is corrected by adopting the real-time temperature T, the humidity H and the current air pressure value measured by the environment parameter detector in the inspiration process, and the volume flow V is corrected by adopting the medical expiration temperature and humidity empirical value in the expiration process. Compared with the prior art, the high-precision ultrasonic lung function detector and the detection method provided by the invention have the following effects: (1) the ultrasonic lung function detector realizes bidirectional flow measurement through the transceiving ultrasonic sensor, improves the transmitting voltage through the booster circuit and the amplitude variation circuit, improves the transmitting voltage, increases the transmitting power, improves the signal-to-noise ratio of a receiving end, reduces the amplification factor, and inhibits self-oscillation and noise; the transmitting signal is prevented from being interfered by space stray signals, particularly pulse groups, through the amplifying circuit and the band-pass filtering circuit, and average value filtering is performed on the abnormal data, so that static data are more stable; shielding cases are arranged outside the amplifying circuit and the band-pass filter circuit to shield electromagnetic radiation interference; the environment parameter detector can acquire the environment temperature and humidity in real time and transmit the temperature and humidity to the controller for real-time correction, so that the use is simpler and more convenient, and the measurement result is more accurate; the method can be suitable for the conditions of patients with different vital capacities to select different bite tubes for testing, and the detection accuracy is improved. (2) In a high flow velocity region, a transmission medium is discontinuous, so that the amplitude of an ultrasonic signal changes, when a fixed threshold value is judged, a preset first wave jump directly adjacent periods easily occurs, the invention adopts a zero-crossing detection correction method, the characteristic of back and forth is inevitable according to the jump of a zero-crossing detection point, a method of correction according to integral multiple of the periods is adopted, data is restored, the continuity of curves is ensured, the traditional average value filtering is avoided, the sharp point of the instantaneous expiratory maximum flow is avoided, the abnormal flow velocity value in a low and high flow velocity region in the measurement process can be corrected accurately and quickly, and the accuracy of the detection value is improved; (3) the invention adopts a real-time compensation correction method to correct the ultrasonic sound velocity, so that the measurement result is more accurate; the invention (4) can measure the flow rate under the condition of completely not obstructing respiration, has no pressure loss, extremely high sensitivity and wide range, and the respiratory flow can be obtained by integral calculation of the measured flow rate.
Drawings
FIG. 1 is a block diagram of the hardware system design of the present invention;
FIG. 2 is a flow velocity-time plot of ultrasonic propagation in a high flow velocity zone;
fig. 3 is a flowchart of the zero-crossing detection correction method.
Detailed Description
In order to make the technical solutions of the present invention better understood, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1-3, a high-precision ultrasonic lung function detector comprises a blowing pipe 1 and a plurality of biting tubes 3, wherein two ultrasonic sensors 2 are arranged on the blowing pipe 1, any biting tube 3 can be movably inserted into the blowing pipe 1, signal output ends of the two ultrasonic sensors 2 are positioned in the blowing pipe 1 and are oppositely arranged, an included angle is formed between a connecting line of the two ultrasonic sensors 2 and the blowing pipe 1, the included angle alpha is 0< alpha <90 degrees, the ultrasonic sensors 2 are connected with a change-over switch, the change-over switch is connected with an amplifying circuit and an amplitude change circuit, the two amplitude change circuits are connected with a same booster circuit and a same pulse emission and precision time measurement chip, the amplifying circuit is connected with a band-pass filter circuit, and shielding cases are arranged outside the amplifying circuit and the band-pass filter circuit, two band-pass filter circuit all with pulse transmission and accurate time measurement chip are connected, pulse transmission and accurate time measurement chip serial communication connect microcontroller, microcontroller controls two respectively change over switch, microcontroller communication connection server, the server electricity is connected with the environmental parameter detector, the environmental parameter detector includes temperature detection module, humidity detection module and atmospheric pressure detection module, and based on the hardware connection more than, the procedure of deuterogamying microcontroller just can utilize zero cross detection correction method and real-time compensation correction method to mutually support and realize high accuracy ultrasonic wave lung function detector function.
Lung function detector detection workflow:
the microcontroller sends a detection starting signal to the pulse transmitting and precise time measuring chip, the upstream ultrasonic sensor is switched to transmit, the downstream ultrasonic sensor is switched to receive, the pulse transmitting and precise time measuring chip starts to time and sends 2 continuous pulse signals, the amplitudes of the 2 pulse signals are increased through the booster circuit and the amplitude change circuit, and the pulse signals are added to the upstream ultrasonic sensor;
the downstream ultrasonic sensor receives ultrasonic signals (the ultrasonic frequency is 20kHZ-30MHz), the ultrasonic signals are processed by an amplifying circuit and a band-pass filter circuit and transmitted to a pulse emission and precise time measurement chip, the pulse emission and precise time measurement chip judges the end of timing according to a set threshold value and a zero crossing point, and the transit time t is calculatedup；
Similarly, the ultrasonic sensor at the upstream is switched to receive the ultrasonic signal, the ultrasonic sensor at the downstream is switched to receive the ultrasonic signal, and the transit time t can be calculated through the same modedown。
The detection method of the high-precision ultrasonic pulmonary function detector comprises the steps of respectively correcting the transit time of ultrasonic signals detected by an ultrasonic sensor in high and low flow velocity areas by adopting a zero-crossing detection correction method, and calculating to obtain volume flow VMeasuring(ii) a And simultaneously adopts a real-time compensation correction method to correct the volume flow VMeasuringReal-time environmental parameter correction is carried out to finally obtain the volume flow VBTPS；
Wherein, the zero-crossing detection correction method is as follows: s1, threshold voltage is set in advance, when the amplitude of a received signal of the ultrasonic sensor reaches a threshold value, zero-crossing detection is started, a plurality of zero-crossing points can be set as timing end points, and transition time t can be obtainedupAnd tdownThrough tupAnd tdownCalculating a fluid flow velocity v; t is tupCalculate using equation 1
Figure RE-GDA0003276943210000091
tdownCalculate using equation 2
Figure RE-GDA0003276943210000092
Wherein L is the sound channel length, c is the ultrasonic sound velocity, theta is the sound channel and pipeline axial included angle, v is the fluid velocity, and the cocurrent and countercurrent transit time difference Deltat adopts formula 3 to calculate:
Figure RE-GDA0003276943210000093
due to c2＞＞v2cos2θ, then Δ t can be simplified to equation 4:
Figure RE-GDA0003276943210000094
the flow velocity v is thus calculated using equation 5:
Figure RE-GDA0003276943210000095
s2, because the ultrasonic wave is greatly propagated and attenuated in the high-flow-velocity gas medium, the preset threshold voltage does not detect the sound wave needing to be detected, namely the sound wave with the lead/lag period is detected, so that the transit time t is made to be longerupOr tdownThe deviations of t' and t "occur at the time points t1, t2 and t3, respectively, for three successive points a, b and c on the flow-time curve defining the breathing process, the corresponding flow rates v being respectively1，v2And v3，Δy1And Δ y2Flow speed difference of two successive points, i.e. Δ y1＝v2-v1，Δy2＝v3-v2Let m be the sum of absolute flow velocities of points a and b, i.e., m ═ v1|+|v2L for judging whether it is a low flow rate region or a high flow rate region, setting mmidIs a limit value when m<mmidWhen m is a low flow rate region>mmidIn the time, the abnormal flow velocity of the high flow velocity region is corrected by respectively adopting different data correction algorithms(ii) a Filtering abnormal data in a low flow velocity region by adopting a mean filtering method, and setting | delta y2|maxThreshold value of abnormal flow velocity data in low flow velocity zone, i.e. | Deltay2|＞|Δy2|maxWhen the flow rate data is abnormal, the corrected flow rate is v3′＝(v1+v2) 2; the following filtering algorithm was used for the anomaly data in the high flow region: let Δ y3＝|Δy1|+|Δy2|, Δ y can be obtained3Time curve, setting decision threshold Δ ymaxWhen Δ y3＞ΔymaxIf it is determined that the data is erroneous, data correction is necessary, and in this case, Δ y is set1>A positive cycle flow difference, the correction method is to subtract Δ t from one ultrasonic clock cycle, i.e., Δ t' ═ Δ t-1/f; if Δ y1<A negative cycle flow rate difference, the correction method is that Δ t plus one ultrasonic clock cycle, namely Δ t ═ Δ t +1/f, and the flow rate values v 'and v "calculated by using Δ t' and Δ t" are corrected flow rate values;
s3. since the measured fluid flow velocity V is actually the linear average velocity on the inner diameter of the section of the pipeline, and the measured flow requires the surface average flow velocity V' of the section of the pipeline, the volume flow VMeasuringThen the calculation is carried out by using the formula (7),
Figure RE-GDA0003276943210000101
wherein t is1And t2D is the diameter of the pipeline, v' ═ kv, and k is the reynolds number correction coefficient;
the real-time compensation correction method comprises the following steps: judging whether the test state of the user is an inspiration process or an expiration process according to the formula (3); when delta T is greater than 0, an inspiration process is carried out, delta T is less than 0, an expiration process is carried out, the real-time temperature T measured by the environment parameter detector is adopted to calibrate the ultrasonic sound velocity c in the inspiration process, the empirical value of the medical expiration temperature is adopted to calibrate the ultrasonic sound velocity c in the expiration process, and the ultrasonic sound velocity c is calibrated by adopting a sound velocity correction formula; when delta t is more than 0, the inspiration process is performed, delta t is less than 0, the expiration process is performed, the real-time temperature measured by the environment parameter detector is adopted in the inspiration processT, humidity H, air pressure P to volume flow VMeasuringCorrecting and exhaling, and measuring volume flow V by using empirical values of medical expiratory temperature and humidityMeasuringCorrection is carried out by using the formula (10), VBTPSCorrection factor x VMeasuring(10) Wherein the correction coefficient is calculated by adopting a BTPS correction formula;
sound velocity correction formula:
Figure RE-GDA0003276943210000102
BTPS correction formula:
Figure RE-GDA0003276943210000103
pw was calculated using the 2000 corrected Goff-Gratch formula.
Finally, it should be noted that the above-mentioned description is only a preferred embodiment of the present invention, and those skilled in the art can make various similar representations without departing from the spirit and scope of the present invention.

Claims (10)

1. The utility model provides a high accuracy ultrasonic wave lung function detector which characterized in that: the device comprises a blowing pipe (1) and a plurality of bite mouth pipes (3), wherein two ultrasonic sensors (2) are arranged on the blowing pipe (1), any bite mouth pipe (3) can movably penetrate through the blowing pipe (1), the signal output ends of the two ultrasonic sensors (2) are positioned in the blowing pipe and are arranged oppositely, the ultrasonic sensors (2) are connected with a change-over switch, the change-over switch is connected with an amplifying circuit and an amplitude change circuit, the two amplitude change circuits are connected with the same boosting circuit and the same pulse emission and precision time measurement chip, the amplifying circuit is connected with a band-pass filter circuit, the two band-pass filter circuits are both connected with the pulse emission and precision time measurement chip, the pulse emission and precision time measurement chip is in serial communication connection with a microcontroller, and the microcontroller controls the two change-over switches respectively, the microcontroller is in communication connection with the server, the server is provided with the environmental parameter detector, and based on the hardware connection, the high-precision ultrasonic lung function detector can be realized by the mutual cooperation of a zero-crossing detection correction method and a real-time compensation correction method by matching with a program of the microcontroller.
2. A high precision ultrasonic lung function detector according to claim 1, wherein: an included angle is formed between a connecting line of the two ultrasonic sensors (2) and the blow pipe (1), and the included angle alpha is 0< alpha <90 degrees.
3. A high precision ultrasonic lung function detector according to claim 1 or 2, wherein: the environment parameter detector comprises a temperature detection module, a humidity detection module and an air pressure detection module.
4. A high precision ultrasonic lung function detector according to claim 1, wherein: and shielding covers are arranged outside the amplifying circuit and the band-pass filter circuit.
5. The detection method of the high-precision ultrasonic lung function detector as claimed in claims 1-4, wherein the detection method comprises the following steps: the microcontroller sends a start detection signal to the pulse transmitting and precise time measuring chip, simultaneously switches the upstream ultrasonic sensor into transmitting, switches the downstream ultrasonic sensor into receiving, starts timing by the pulse transmitting and precise time measuring chip and sends 2 continuous pulse signals, the amplitude of the 2 pulse signals is increased through the booster circuit and the amplitude variation circuit and is added to the upstream ultrasonic sensor, the downstream ultrasonic sensor receives the ultrasonic signals, the ultrasonic signals are processed by the amplifying circuit and the band-pass filter circuit and are transmitted to the pulse transmitting and precise time measuring chip, the pulse transmitting and precise time measuring chip judges the timing end according to the set threshold value and the zero crossing point, and the transit time t is calculatedup(ii) a The upstream ultrasonic sensor is switched to receive ultrasonic signals, the downstream ultrasonic sensor is switched to receive ultrasonic signals, and the transit time t can be calculated through the same modedown(ii) a For the transit time t measured in the high and low flow velocity regionsupAnd tdownRespectively correcting by adopting a zero-crossing detection correction method, and calculating to obtain the volume flow VMeasuring(ii) a And simultaneously adopts a real-time compensation correction method to correct the volume flow VMeasuringReal-time environmental parameter correction is carried out to finally obtain the volume flow VBTPS。
6. The detecting method of the high-precision ultrasonic lung function detector according to claim 5, wherein: the zero-crossing detection correction method comprises the following steps: s1, threshold voltage is set in advance, when the amplitude of a received signal of the ultrasonic sensor reaches a threshold value, zero-crossing detection is started, a plurality of zero-crossing points can be set as timing end points, and transition time t can be obtainedupAnd tdownThrough tupAnd tdownCalculating a fluid flow velocity v; s2, because the ultrasonic wave is greatly propagated and attenuated in the high-flow-velocity gas medium, the preset threshold voltage does not detect the sound wave needing to be detected, namely the sound wave with the lead/lag period is detected, so that the transit time t is made to be longerupOr tdownThe deviations of t' and t "occur at the time points t1, t2 and t3, respectively, for three successive points a, b and c on the flow-time curve defining the breathing process, the corresponding flow rates v being respectively1，v2And v3，Δy1And Δ y2Flow speed difference of two successive points, i.e. Δ y1＝v2-v1，Δy2＝v3-v2Let m be the sum of absolute flow velocities of points a and b, i.e., m ═ v1|+|v2L for judging whether it is a low flow rate region or a high flow rate region, setting mmidIs a limit value when m < mmidWhen m is greater than m, the flow velocity is in a low flow velocity regionmidIn the time, the abnormal flow velocity of the high flow velocity region is corrected by adopting different data correction algorithms respectively; s3. since the measured fluid flow velocity V is actually the linear average velocity on the inner diameter of the section of the pipeline, and the measured flow requires the surface average flow velocity V' of the section of the pipeline, the volume flow VMeasuringThen the calculation is carried out by using the formula (7),
Figure FDA0003188252910000031
S＝π(D/2)2(7) (ii) a Wherein t is1And t2To determine the time when the flow measurement starts and ends, D is the diameter of the pipe, v' ═ kv, and k is the reynolds number correction factor.
7. The detecting method of the high-precision ultrasonic lung function detector according to claim 6, wherein: in said S1: t is tupCalculate using equation 1
Figure RE-FDA0003276943200000032
tdownCalculate using equation 2
Figure RE-FDA0003276943200000033
Wherein L is the sound channel length, c is the ultrasonic sound velocity, theta is the sound channel and pipeline axial included angle, v is the fluid velocity, and the cocurrent and countercurrent transit time difference Deltat adopts formula 3 to calculate:
Figure RE-FDA0003276943200000034
due to c2＞＞v2cos2θ, then Δ t can be simplified to equation 4:
Figure RE-FDA0003276943200000035
the flow velocity v is thus calculated using equation 5:
Figure RE-FDA0003276943200000036
8. the detecting method of the high-precision ultrasonic lung function detector according to claim 6, wherein: in the step S2, a mean value filtering is applied to the abnormal data in the low flow rate regionWave-wise filtering, let | Δ y2|maxThreshold value of abnormal flow velocity data in low flow velocity zone, i.e. | Deltay2|＞|Δy2|maxWhen the flow rate data is abnormal, the corrected flow rate is v3′＝(v1+v2) 2; the following filtering algorithm was used for the anomaly data in the high flow region: let Δ y3＝|Δy1|+|Δy2|, Δ y can be obtained3Time curve, setting decision threshold Δ ymaxWhen Δ y3＞ΔymaxIf it is determined that the data is erroneous, data correction is necessary, and in this case, Δ y is set1If the flow rate difference is more than one positive period, the correction method is that the ultrasonic clock period is subtracted from the delta t, namely delta t-1/f; if Δ y1If the flow rate difference is less than one negative cycle, the correction method is to add Δ t to one ultrasonic clock cycle, i.e., Δ t ″ ═ Δ t +1/f, and the flow rate values v 'and v ″ calculated using Δ t' and Δ t ″ are corrected flow rate values.
9. The detecting method of the high-precision ultrasonic lung function detector according to claim 5, wherein: the real-time compensation correction method comprises the following steps: s1, judging whether the test state of a user is an inspiration process or an expiration process according to the formula (3); s2, sound velocity correction: respectively correcting the ultrasonic sound velocity c by adopting a sound velocity correction formula according to different test states; s3, real-time BTPS correction: for different test states, the volume flow V is respectively adjustedMeasuringCorrection by the formula (10), VBTPSCorrection factor x VMeasuring(10) Wherein the correction coefficient is calculated using a BTPS correction formula.
10. The detecting method of the high-precision ultrasonic lung function detector according to claim 9, wherein: the sound velocity correction specifically comprises: when delta T is greater than 0, the inspiration process is carried out, delta T is less than 0, the expiration process is carried out, the real-time temperature T measured by the environment parameter detector is adopted to calibrate the ultrasonic sound velocity c, and the expiration process is carried out by adopting the medical expiration temperature empirical value to calibrate the ultrasonic sound velocity c; the real-time BTPS correction specifically comprises the following steps: when delta T is more than 0, the inspiration process is carried out, delta T is less than 0, the expiration process is carried out, the volume flow V is corrected by adopting the real-time temperature T, the humidity H and the current air pressure value measured by the environment parameter detector in the inspiration process, and the volume flow V is corrected by adopting the medical expiration temperature and humidity empirical value in the expiration process.
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