SU1623611A1 - Device for measuring volume rate of external respiration - Google Patents

Abstract

The invention relates to medical technology and permits an increase in the accuracy of measuring the volumetric rate of external respiration due to the correction of nonlinearity by piecewise linear approximation of the transfer function. The device contains a series-connected air flow to pressure differential converter 1, an electro-electrometer 3, an amplifier 4, an ADC 6, a programmable calculator 7 and a recorder 8, as well as additionally entered unit 1 of potentiometers, switch 5, pneumatic valve 2, generator 11, register 10, DAC 13, trigger 12 and comparator 9 3 sludge,

Description

The invention relates to medical technology and can be used to study the functions of external respiration.

The purpose of the invention is to increase the volume of measuring the volumetric rate by correcting the nonlinearity of the converter.

FIG. 1 shows a block diagram of a device for measuring the volume velocity of external respiration; in fig. 2 is a block diagram of the device operation algorithm; in fig. 3 - graphs of the dependence of the output voltage of the amplifier on the input voltage (a) and the calculated values on the input voltage (b).

The device contains an air flow converter 1, a pneumatic valve 2, an electromagnet 3, an amplifier 4, a switch 5, an ADC 6, a programmable calculator 7, a recorder 8, a comparator 9, a register 10, a generator 11. a trigger 12, a DAC 13, a potentiometer block 14.

The operation algorithm of the device is determined by the operation program stored in the ROM of the calculator 7. The flowchart (FIG. 2) allows

a program in the assembler language, for example the KR58SIK80 microprocessor, or another high-urn language

Designation of program blocks: 18-started by pressing the Reset button. 19-initialization of K580IK55- one port for input, two for output, K580IK53 - setting the period of pulses in a periodic mode;

20- Button 1 pressed:

21- Button 2 is pressed;

22- linearization mode;

23- mode for determining the new correction function;

24- issue of a switch code connecting potentiometer 12;

25- End Conversion ADC

26- receiving the R code from the ADC and writing to the RAM cell;

27- All potentiometers surveyed;

28- increase the address of the RAM cell, issue the switch code, the next potentiometer;

29- calculation of Kj Rj + 1 / Ri;

30-memorization K) in the cells of RAM;

(L

WITH

31- Linearization mode;

32- Start button pressed (after connecting the patient to the tube);

33- issuing the code of the switch connecting the amplifier;

34- End Conversion

35- receiving the NI code from the ADC and writing to the RAM cell;

36- choice of the parameter Kj;

37- Transition to the next approximation area;

38- connection to the comparator via the switch of the next potentiometer, turning on the valve, setting the trigger

in g;

39 - delay at the time of establishing a new value, recovery;

40- Ni calculation (K);

41- storing in the RAM;

42 output to the registering device;

43- Linearization mode;

44- Stop button pressed;

45- end of measurement.

Plus means Yes, minus - No.

The graph of the output voltage of the amplifier versus the input voltage (Fig. 3a) shows the output voltage spikes at the approximation nodes due to the supply of a new level of bias.

The plot of the calculated values as a function of the input voltage (Fig. 36) shows the correction of the path nonlinearity due to the approximation by a piecewise linear fraction. The dash-dotted lines show the parts of the function with a discontinuity, if no new level of bias was applied to the amplifier at each site.

A device for measuring the volumetric respiration rate can operate in two modes; the linearization mode of the output characteristic of the flow converter according to the specified correction factors and the mode of determining the new correction function (correction factors) instead of the previous one.

In the linearization mode, the output characteristics of the device works as follows.,

At the beginning of the work, before the measurement, by pressing the Reset button, and then the buttons of the control panel, in the RAM cells of the calculator 7, codes corresponding to the voltages set on the potentiometers of the potentiometer block 14 are memorized. Thus, first, potentiometer 15 of unit 14 is connected to analog-to-digital converter 6 via switch 5 and the resulting RI code is stored in the memory cell.

Then, potentiometers 15, 17 are connected in series to analog-to-digital converter 6, and codes R2 are stored in the cells. R3 ... Km. Where I is the number of intervals of a piecewise linear function.

Thus, the number of potentiometers of block 14 depends on the chosen number of intervals of the piecewise linear function and is one more than this number.

Correction factors are determined by dividing the codes Ra ... RM by RL. Thus, the coefficient of the first part of the characteristics is defined as Ki R2 / R1, and the sequence R | + 1 him Kj W -r-.

With the linear characteristic of the converter RI R2 .. P | tivseK1 Ki are equal to one.

The obtained quotients from the division are stored in the cells of block 7 and further serve to correct the measurement results.

After calculating and storing the correction factors, the actual measurement and linearization of the volumetric velocity values are performed. This program starts by pressing the Start button.

When air flow V passes through converter 1, a pressure difference arises at its outlet. This pressure difference flows through clan i 2 to the inlet of electromanometer 3, and a potential difference D appears at its output, which is amplified by amplifier 4.

The output voltage from the amplifier i is fed through the switch 5 to the input of the analog-digital converter in the form of an NI code stored in the RAM of the calculator 7.

The ADC is triggered by a program timer pulse. The period of these pulses determines the sampling interval of the signal and is, for example, 10 ms.

Further, the current NI code enters the central processor of the calculator 7. From its value it is determined on which segment of the piecewise linear function this count lies.

The value of the correction coefficient corresponding to the given segment is selected from the memory cells. If the current value goes to the next piece of the piecewise linear function as compared to the previous values, then the amplifier 4 is supplied with a new level of displacement. The programmable calculator 7 supplies the switch 5 with a code that connects the potentiometer of this section of the function to the comparator 9 and turns off the pneumatic valve 2. The trigger 12 is given a signal from the programmable calculator 7, which sets the trigger 12 to state 1. The signal from trigger 12 starts the register 10 on write code to register. With the arrival of each pulse from the generator 11, the state of the comparator 9 is sequentially recorded in the register. The first pulse records the state of the comparator 9 comparing the voltage at the output of the amplifier 4 with the air flow shut off and the voltage coming from the potentiometer plot. The first pulse resets the trigger to the state About. The code from the register goes to the DAC 13, and the output voltage from the DAC enters the bias input of the amplifier 4. The next pulse from the generator 11 records the comparator status determined by the updated value bias amplifier 4 and potentiometer. Each subsequent pulse from generator 11 approximates the value of the code in register 10 to the corresponding voltage on the potentiometer.

In total, the total number of pulses corresponding to the register distance, for example, 12, goes to register 10 from the generator 11. For example, this vo / i, the pre-sent DAC 13, will not be stored in register 1C until the next pulse is received. you-od 1 trip shout 12

Then, the programmable digitizer 7 turns on valve 2 and restores the code on switch 5. which connects amplifier 4 to the A / D converter 6. Then calculate and correct the calculation of the corrected value using formula (1).

The calculated result N i is sent to the on-line memory and then output to the recorder 8. The curve of the flow rate versus time is displayed on the monitor screen.

In the same way as in determining the correction factors, the above-described operations for measuring and linearizing the speed are performed by commands that are read from the ROM and are converted by u-leveling signals in the central processor of the calculator 7.

In the mode of determining the new correction function instead of the previous one, the device works as follows.

The flow converter 1 is supplied with a constant air flow from the reference flow generator. Then, almost the same program is executed as in the measurement, which is triggered by pressing the 2 m button. Correction factors are determined, the flow rate is recorded, linearity is corrected by the formula (1) and the measurement result is output to the recorder 8. These operations are carried out periodically, for example, every 1-2 seconds.

If given from the reference generator

the flow is in the range of the first section of the piecewise linear function and the value not corresponding to this flow is displayed on the recorder 8, the operator, by turning the potentiometer 14, changes the code

The correction coefficient of the first section KL is also changed. At the same time, the slope of the first section of the characteristic changes, and hence the recorded value. Change the flow from the reference generator, respectively, in the range

the subsequent sections of the characteristic and rotating the corresponding potentiometers, it is possible to change the correction factors on these sections.

Consequently, the wire is periodically calibrated, it is possible to change, if necessary, the characteristic of the approximating function.

Claims (1)

Invention Formula A device for measuring the volumetric rate of external respiration, containing series-connected air flow in the longitudinal section. t / electromanager, amplifier, analogue digital and converter, programmable transmitter and recorder, the inputs of which are connected to the first outputs of the calculator, the second output of the calculator is connected to A control input of an analog-digital converter, characterized in that, in order to increase the measurement accuracy of the volumetric speed by correcting the non-linearity of the converter, a potentiometer unit is inserted into it. a switch, a pneumatic valve, a generator, a register, a digital-to-analog converter, a trigger and a comparator, the outputs of the potentiometers and the amplifier are connected via a switch to the input the analog-digital converter and the first input of the comparator, the second input of which is connected to the amplifier output, and the output to the information input of the register, the third outputs of the programmable calculator are connected to the control inputs of the switch, the fourth output. - to the installation input of the trigger, and the fifth output to the control input of the valve, which is connected between the flow converter and the electromanometer, the generator output is connected to the synchronous inputs of the trigger register, the information input of the amplifier, and the output of the trigger outputs of which are connected via a digital-to-analog converter with the second connected to the enable input. I I ze 4J Awr X Ub Fig.Z