CN210990300U - Automatic correction system for lung function measurement zero drift - Google Patents
Automatic correction system for lung function measurement zero drift Download PDFInfo
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- CN210990300U CN210990300U CN201921512287.0U CN201921512287U CN210990300U CN 210990300 U CN210990300 U CN 210990300U CN 201921512287 U CN201921512287 U CN 201921512287U CN 210990300 U CN210990300 U CN 210990300U
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Abstract
The utility model relates to a pulmonary function measures drift automatic correction system at zero point. An automatic correction system for lung function measurement zero drift, comprising: the system comprises a first differential pressure sensor, a second differential pressure sensor, a signal amplification unit, a low-pass filtering unit, an external high-precision AD acquisition unit and a microcontroller; the first differential pressure sensor and the second differential pressure sensor are respectively connected with the signal amplification unit and the low-pass filtering unit in sequence and then are jointly connected with the external high-precision AD acquisition unit and the microcontroller; the pressure difference collected by the first differential pressure sensor and the second differential pressure sensor is converted into flow through the corresponding relation between pressure and flow, the volume is calculated through the integration of the flow and time, zero point correction is carried out in real time in the measuring process, the influence of zero point drift on the measuring result is reduced, and a smoother and stable respiration signal and an accurate lung function measuring result are obtained.
Description
Technical Field
The utility model relates to a lung function measuring technical field which is used for medical equipment and adopts a piezoresistive pressure sensor as a measuring element and measures in a differential pressure mode. In particular to an automatic correction system for zero drift of lung function measurement.
Background
The lung function examination is an examination that combines modern medical examination techniques and respiratory physiological mechanisms to explore the lung ventilation function and pathophysiological changes. The examination commonly used in clinic includes lung volume examination, spirometer examination, bronchial excitation test, bronchial relaxation test, lung diffusion function examination, airway resistance examination, exercise cardiopulmonary examination and the like. Among them, the examination of the ventilatory function using a flow-type spirometer detection device has been developed into the most commonly used means for detecting pulmonary function in clinical practice. The respiratory flow and the volume are used as two key indexes of the lung function measurement, and the accuracy of the lung function measurement result is related. Therefore, in the measurement of lung function, factors influencing the flow and the measurement accuracy of volume are fully considered, and various influencing factors are reduced or eliminated from the system design so as to ensure the accuracy of the measurement of lung function.
In accordance with different measurement principles, gas flow measurement methods are widely used at present, such as differential pressure type flow measurement, float flow measurement, turbine type flow measurement, ultrasonic type flow measurement, electromagnetic type flow measurement, and the like.
The prior art generally adopts a single sensor, and performs zero calibration once before each measurement to correct the zero drift of the sensor. However, when the piezoresistive pressure sensor generates zero drift along with the change of the spatial direction, the volume error is accumulated to have larger and larger deviation along with the time, and the method cannot effectively correct the breathing volume.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a there is this problem of drift at zero point to piezoresistive pressure sensor along with the change of space direction, can be real-time effectual rectify, and then realize carrying out the automatic correction to the key index of pulmonary function-breathing gas flow and volumetric drift at zero point, adopt differential pressure formula flow measurement technique, piezoresistive pressure sensor's pulmonary function measurement drift at zero point automatic correction system promptly.
The technical solution of the utility model is that the lung function measures drift automatic correction system at zero point, its special character lies in, include: the system comprises a first differential pressure sensor, a second differential pressure sensor, a signal amplification unit, a low-pass filtering unit, an external high-precision AD acquisition unit and a microcontroller; the first differential pressure sensor and the second differential pressure sensor are respectively connected to an external high-precision AD acquisition unit and a microcontroller together through a signal amplification unit and a low-pass filtering unit which are sequentially connected; the pressure difference collected by the first differential pressure sensor and the second differential pressure sensor is converted into flow through the corresponding relation between pressure and flow, the volume is calculated through the integration of the flow and time, zero point correction is carried out in real time in the measuring process, the influence of zero point drift on the measuring result is reduced, and a smoother and stable respiration signal and an accurate lung function measuring result are obtained.
Compared with the prior art, the beneficial effects of the utility model are that:
⑴ the utility model discloses possible real-time correction sensor's drift at zero point reduces volume measuring error as far as possible, improves system measurement accuracy.
⑵ the utility model discloses an in the pulmonary function measurement, based on the drift automatic correction method of two sensors, reflect measuring sensor's state at zero point in real time through the reference sensor, measuring sensor can accomplish real-time automatic correction at zero point for system stability and accuracy can promote, and the precision of pulmonary function measurement parameter has also obtained the promotion.
⑶ the differential pressure type flow rate measurement has advantages in measuring range, measuring precision and process cost, so the utility model discloses a differential pressure type flow rate method measures the respiratory flow rate of human body.
Drawings
FIG. 1 is a block diagram of an automatic calibration system for lung function measurement zero drift measured by differential pressure using a dual differential pressure sensor as a measurement element;
fig. 2 is a flow chart of the method for automatically correcting the zero drift of lung function measurement according to the present invention.
Detailed Description
The utility model discloses the following will make further detail with the accompanying drawing:
referring to fig. 1, the system hardware of the present invention adopts a double differential pressure sensor design, wherein the first sensor is connected to the human breath gas circuit for collecting the differential pressure generated by human breath; the second sensor is not connected with any gas circuit, and provides a zero state for the first sensor in real time.
⑴ before measurement, the pressure ports of the first and second sensors are communicated via gas circuit, and the pressure ports of the first and second sensors are communicated, and calibrated, and the sampling results of the first and second sensors can be converted via corresponding relationship after calibration;
⑵ after calibration before measurement, when in measurement state, the real-time measurement data of the second sensor is converted through the conversion relation between the two sensors to reflect the zero state of the first sensor in real time;
⑶ when the space direction of the sensor changes, the zero point change trends of the same type of piezoresistive pressure sensor are consistent, and the automatic correction of the zero point drift is realized.
This flow measurement method is that the differential pressure that gathers differential pressure sensor converts the flow into through the corresponding relation of pressure and flow, calculates the volume by the integral of flow to time again, and on fluctuation of this in-process differential pressure sensor at zero point moment will be along with the gradual accumulation of time to the volume, volume error will crescent influence the accuracy of pulmonary function measurement, the utility model discloses a zero drift automatic correction method can be in the real-time correction of carrying out zero point of measurement in-process to reduce the influence of zero drift to the measuring result as far as, obtain more smooth stable respiratory signal and accurate pulmonary function measuring result.
⑴ calibrating the sensors, namely, a first sensor and a second sensor on a lung function measuring board card adopt differential pressure sensors of the same model, the sensors are provided with two pressure guide ports, the pressure guide ports of the first sensor and the second sensor are connected together through an air passage, the pressure guide ports of the first sensor and the second sensor are communicated, and the two sensors are calibrated simultaneously, so that the relation between sampling values and actual pressure values obtained by the two sensors through AD conversion is respectively obtained:
the first sensor calibration formula is: y is1＝K1*X1+B1； ⑴
In the formula, X1Representing sampled values, Y, of the sensor 1 obtained by a high accuracy AD1Representing the actual measured differential pressure value of the first sensor, K1And B1Represents X1And Y1A constant in a linear relationship;
the second sensor calibration formula is as follows: y is2＝K2*X2+B2； ⑵
In the formula, X2Representing sampled values, Y, of the sensor 2 obtained with high precision AD2Representing the value of the differential pressure, K, actually measured by the second sensor2And B2Represents X2And Y2A constant in a linear relationship;
⑵ the conversion relationship between the two sensors is obtained according to the zero values obtained by equations ⑴ and ⑵ when the sensors are in different directions:
Y1＝C*Y2⑶
in the formula, C represents a relation constant between the differential pressure values actually measured by the sensor 1 and the sensor 2;
⑶ when the second sensor measures Y2If the value is larger than the set threshold value, the zero drift of the second sensor is judged, and the zero drift value Y of the first sensor is calculated according to a formula ⑶1 (zero point)＝C*Y2 (zero point)；
⑷ the first sensor performs real-time zero correction to obtain a corrected measured value P:
P＝Y1-Y1 (zero point)。
Referring to fig. 2, the method for automatically correcting the zero drift of lung function measurement includes:
⑴ starting the system to calibrate the first sensor and the second sensor respectively;
⑵ obtaining a translation between the first sensor and the second sensor;
⑶ collecting signals of the first sensor and the second sensor;
⑷, judging whether the second sensor has zero drift, if not, going to step ⑺, and if so, going to step ⑸;
⑸ converting the zero offset value of the second sensor to a zero drift value of the first sensor by a conversion relationship;
⑹ zero point correction of the first sensor, i.e. difference between the first sensor value and the zero point drift value;
⑺ obtaining flow rate through pressure-flow rate corresponding relation, and obtaining capacity through flow rate integration to time;
⑻, it is judged whether or not the measurement is completed, and if not, the procedure returns to step ⑶, and if yes, the procedure is ended.
The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made according to the scope of the claims of the present invention should be covered by the claims of the present invention.
Claims (1)
1. An automatic correction system for lung function measurement zero drift, comprising: the system comprises a first differential pressure sensor, a second differential pressure sensor, a signal amplification unit, a low-pass filtering unit, an external high-precision AD acquisition unit and a microcontroller; the first differential pressure sensor and the second differential pressure sensor are respectively connected to an external high-precision AD acquisition unit and a microcontroller together through a signal amplification unit and a low-pass filtering unit which are sequentially connected; the pressure difference collected by the first differential pressure sensor and the second differential pressure sensor is converted into flow through the corresponding relation between pressure and flow, the volume is calculated through the integration of the flow and time, zero point correction is carried out in real time in the measuring process, the influence of zero point drift on the measuring result is reduced, and a smoother and stable respiration signal and an accurate lung function measuring result are obtained.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112325994A (en) * | 2020-11-04 | 2021-02-05 | 合肥科迈捷智能传感技术有限公司 | Automatic correction method for zero offset of differential pressure flowmeter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112325994A (en) * | 2020-11-04 | 2021-02-05 | 合肥科迈捷智能传感技术有限公司 | Automatic correction method for zero offset of differential pressure flowmeter |
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