Breathing simulation system and compensation method thereof

Abstract

The invention provides a breathing simulation system. The breathing simulation system comprises a mechanical system and a control system. The mechanical system comprises a piston barrel, a connecting device and a driving device, the piston barrel comprises a piston cylinder and a piston, the piston is axially arranged in the piston cylinder, the driving device comprises a servo motor, a ball screw, a sliding table, a limiting stopper and a coupler, and the servo motor is connected with the ball screw through the coupler so as to drive the sliding table to do specified motion. The connecting device comprises a piston connecting rod, a connecting panel, a driving connecting rod and a driving panel. The control system comprises a controller and a computer. The controller is in bidirectional connection with the servo motor, the computer, the temperature transmitter, the humidity transmitter, the pressure transmitter, the in-cylinder pressure transmitter and the flow measuring device. The computer is suitable for writing a control program through software, establishing a standard respiration model according to a standard respiration curve, setting a plurality of calibration parameters and calculating motion compensation. The invention further provides a compensation method for improving simulation precision.

Description

Technical Field

[0001] The invention belongs to the technical field of medical devices, and in particular relates to a high-precision breathing simulation system capable of calibrating a pulmonary function instrument and a compensation method thereof. Background Art

[0002] The breathing simulation system uses the movement of the piston in the piston cylinder to simulate human breathing, outputs a standard air flow that complies with the corresponding calibration procedures to the pulmonary function meter, and thus calibrates the pulmonary function meter. Different pulmonary function meters may produce very different results when testing the same patient, which brings certain difficulties to clinical diagnosis. To solve the problem that different pulmonary function meters will produce too large differences when measuring the same object, it is necessary to have an excellent breathing simulation system to calibrate the pulmonary function meter.

[0003] There are two types of piston push rods in existing breathing simulation systems. One type is that there is no guide rod installed inside the piston cylinder. It is pushed forward by a single push rod, which can simplify the device structure and facilitate the calculation of gas flow and uncertainty assessment, but the operation error is large. The other type is to install several guide rods through the piston cylinder to reduce the eccentricity of the piston movement, but this will increase the difficulty of flow calculation and uncertainty assessment. In addition, the existing breathing simulation system occupies a large area, which is not conducive to carrying out work.

[0004] Due to factors such as device design, transmission method, and manufacturing process, the existing breathing simulation system has large friction and poor coordination between components during movement. The piston cylinder of the breathing simulation system also has manufacturing errors during the manufacturing process and will wear out after working for a period of time, resulting in a deviation between the flow rate output by the breathing simulation system and the required flow rate. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the present invention provides a breathing simulation system and a compensation method thereof.

[0006] The present invention provides a breathing simulation system, including a mechanical system and a control system;

[0007] The mechanical system includes a piston cylinder, a connecting device and a driving device;

[0008] The piston cylinder comprises a piston cylinder, a front end plate, a rear end plate, a bottom plate, a piston and an outlet panel, the piston can be axially movably arranged in the piston cylinder, the front end plate and the rear end plate are assembled at the axial ends of the piston cylinder, the bottom plate is suitable for supporting the front end plate and the rear end plate, the outlet panel is installed on the front end plate, the outlet panel is processed to form a flow output port, the front end plate is processed to form a circular hole suitable for connecting the piston cylinder with the flow output port, the rear end plate is processed to form a plurality of rear end vent holes suitable for connecting the piston cylinder with the external environment, and the bottom plate is suitable for being detachably installed on a movable platform and an immovable platform;

[0009] The connecting device comprises a piston connecting rod, a driving connecting rod, a linear bearing, a nut, a connecting panel and a driving panel, wherein the connecting panel is arranged on the outer side of the rear end plate, the driving panel is fixedly arranged on the slide, the driving connecting rod is suitable for connecting the driving panel and the connecting panel and being fixed by the nut, the piston connecting rod is suitable for connecting the connecting panel and the piston and being fixed by the nut, the linear bearing is installed on the rear end plate, and the piston connecting rod and the driving connecting rod pass through the linear bearing;

[0010] The driving device includes a servo motor, a ball screw, a slide, a first limiter and a second limiter. The servo motor is connected to the ball screw through a coupling to drive the slide to perform reciprocating linear motion to simulate human breathing. The first limiter and the second limiter are respectively arranged adjacent to the axial ends of the ball screw. The first limiter and the second limiter are suitable for limiting the motion range of the slide, thereby limiting the motion range of the piston to prevent damage to the breathing simulation device.

[0011] Preferably, the piston cylinder includes a first axis extending along its axial direction, the first axis is perpendicular to the front end plate and the rear end plate, the first axis is parallel to the bottom plate, the first axis is suitable for passing through the center points of both ends of the piston cylinder, the center of the front end circular hole and the center of the piston, and the rear end vent hole is symmetrically arranged about the first axis.

[0012] Preferably, the outlet panel includes a second axis extending along its axial direction, the second axis is suitable for passing through the center of the flow outlet, and the first axis coincides with the second axis.

[0013] Preferably, the piston connecting rod is symmetrically arranged on both sides, the piston connecting rod is arranged perpendicular to the piston and the connecting panel, one end of the piston connecting rod is fixedly connected to the piston or integrally formed, and the other end of the piston connecting rod is fixed to the connecting panel.

[0014] Preferably, the driving connecting rod is arranged symmetrically on the left and right, the driving connecting rod is arranged perpendicular to the driving panel and the connecting panel, one end of the driving connecting rod is fixed to the connecting panel, and the other end of the driving connecting rod is fixed to the driving panel.

[0015] Preferably, the rear end plate includes a square opening arranged at the lower end thereof, and the servo motor is embedded in the square opening.

[0016] Preferably, the rear end plate includes a plurality of through holes arranged in the middle or upper part thereof, and linear bearings are installed in the through holes. The linear bearings include bearing sleeves and a plurality of balls fastened and assembled in the through holes. The balls are suitable for supporting the piston connecting rod or the driving connecting rod and for transmitting axial loads.

[0017] Preferably, the lower end of the front end plate and the lower end of the rear end plate are assembled at the two axial ends of the bottom plate and enclose to form an installation space suitable for accommodating the drive device, and the drive device is packaged and fixed to the bottom plate after assembly.

[0018] The control system includes a controller and a computer;

[0019] The controller is bidirectionally connected to the servo motor, the computer, the temperature transmitter, the humidity transmitter, the pressure transmitter, the cylinder pressure transmitter, and the flow measurement device respectively;

[0020] The computer writes a control program through software, establishes a standard breathing model according to a standard breathing curve, sets several calibration parameters, and establishes a mathematical model inside the piston cylinder by sampling the actual output flow rate, and can perform motion compensation for the displacement and speed of the piston in subsequent use.

[0021] A compensation method for a high-precision breathing simulation system, which is suitable for calibrating and compensating the breathing simulation system as described above, comprises:

[0022] 1. Check the air tightness of the piston cylinder:

[0023] 1-1 Seal the flow output port of the piston cylinder, start the pressure transmitter in the cylinder, and record the reading P0 of the pressure transmitter in the cylinder at this time;

[0024] 1-2 Divide the total stroke L into n sub-strokes evenly, and the length of the sub-stroke is Let the position of each segment point be x i , x n coincides with the end point of the trip;

[0025] 1-3 Servo motor drives the piston to move l i, i∈[1,n], the horizontal load capacity of the servo motor is F, and the pressure gauge reading in the cylinder is P i ;

[0026] 1-4 If P i If the pressure rises first and then falls, it is considered that the sealing of this section of the piston cylinder is insufficient; if P i near It is necessary to unseal and reduce the pressure, then reseal, re-read P0 as the reference value for the next stage, and repeat steps 1.1 to 1.3.

[0027] 1-5 Repeat steps 1.1 to 1.4 to test the sealing of the piston cylinder section by section.

[0028] 2. Model the piston cylinder and obtain the compensation coefficient:

[0029] 2-1 Connect the flow measurement device to the breathing simulation system. The computer sends a command to the breathing simulation system and starts the flow measurement device at the same time. The servo motor causes the piston to complete a uniform motion of a stroke L at a speed v0. The flow measurement device measures the output flow Q(t) of the breathing simulation device during this process. These data are collected centrally, and liquid can be used instead of gas to obtain better data.

[0030] 2-2 The corresponding relationship between x and Q(t), i.e., Q(x), is obtained through x=v0t, where x is the actual stroke position of the piston and A is the cross section of the piston cylinder. In theory, Q(x)=v0A is a constant value, but because there is an error and it is believed that it is mainly the processing error of the piston cylinder, Q(x) will fluctuate in reality;

[0031] The piston cylinder model is established, and in x∈[x i-1 ,x i ) is considered that the piston cross-sectional area is A i , Actual piston cylinder cross-sectional area A i The difference from the theoretical piston cylinder area A is ΔA i , i∈[1,n], and then we get A i The corresponding relationship with x and ΔA i Corresponding to x, that is ΔA(x i )=A(x i )-A, and A(x i ) is abbreviated as A i , ΔA(x i ) is abbreviated as ΔA i ;

[0032] 2-3 The running speed of the piston that needs to be compensated for each sub-stroke

[0033] 2-4 When the breathing simulation system performs other functions, input the set volume V and obtain the current piston position x, x∈[x n ,x n+1 ), when the piston is set to move from the first stopper to the second stopper, calculate the volume margin V that the piston can move 暂 =(x n+1 -x)A n+1 When the piston is set to move from the second stopper to the first stopper, calculate the volume margin V of the piston that can move 暂 =(xx n )A n+1 ;

[0034] 2-5 When the piston is set to move from the first stopper to the second stopper, the parameter j is initialized to 0, and the volume margin V is temporarily compared with the input volume V:

[0035] If V 暂 >V, then j=0,

[0036] If V 暂 <V, then j+1, and on the volume margin V 暂 =(x n+1 -x)A n+1 Plus the volume of the next interval

[0037] Compare it with V again, if it is less than V, continue to add until V 暂 >V, then determine the size of j;

[0038] If j = 1, then

[0039] If j≥2, change j-1, and we get:

[0040] 2-6 When the piston is set to move from the second stopper to the first stopper, the parameter j is initialized to 0 and the volume margin V 暂 Compare with input volume V;

[0041] If V 暂 >V, then j=0,

[0042] If V 暂 <V, then j+1, and on the volume margin V 暂 =(xx n )A n+1 Plus the volume of the next interval

[0043] Compare it with V again, if it is less than V, continue to add until V 暂 >V, then determine the size of j;

[0044] If j = 1, then

[0045] If j≥2, change j-1, and we get:

[0046] In summary, the piston movement distance and speed after compensation correction can be obtained.

[0047] 4.3. Model the piston cylinder to obtain the compression compensation coefficient, that is, the coefficient of the relationship between the piston movement speed and the gas flow output:

[0048] A mathematical model is established based on the one-dimensional steady adiabatic isentropic flow, and the relationship between the gas parameters in the piston cylinder, the gas flow output port parameters, and the stagnation state parameters are listed:

[0049] According to the law of conservation of energy:

[0050]

[0051] P r Stagnation state pressure

[0052] T r Stagnation temperature

[0053] ρ r Stasis state density

[0054] P1: Gas pressure in piston cylinder

[0055] T1: Gas temperature in piston cylinder

[0056] ρ1: Gas density in piston cylinder

[0057] A1: Piston cross-sectional area

[0058] v1: Use piston movement speed

[0059] P2: Gas flow output pressure

[0060] T2: Gas flow output temperature

[0061] ρ2: Gas flow output density

[0062] A2: Cross-sectional area of ​​air flow output port

[0063] v2: Gas flow rate at the gas flow output port

[0064] Where k is the gas insulation coefficient. If the gas is air, k = 1.4

[0065] According to the ideal gas state equation:

[0066] P r =ρ r RT r ...(3)

[0067] P1=ρ1RT1...(4)

[0068] P2=ρ2RT2...(5)

[0069] R is the gas constant, the value is R = 287 (J / kg*K)

[0070] According to the isentropic relationship:

[0071]

[0072] From equations (2) to (6), we can get:

[0073]

[0074]

[0075] According to the law of conservation of mass:

[0076] Q m =ρ1v1A1=ρ2v2A2...(10)

[0077] Substituting (8) and (9) into (10), we can obtain:

[0078]

[0079] The stagnation temperature T r , gas constant R, piston cross-sectional area A1, gas flow output cross-sectional area A2, and gas adiabatic coefficient k are all constants, and compensation operation is performed according to the relationship between the piston movement speed v1 and the gas flow rate v2 at the gas flow output port. The gas flow rate v2 at the gas flow output port is set according to the simulation needs to obtain the piston movement speed v1 required by the piston.

[0080] The beneficial effects of the present invention are:

[0081] (1) By setting a plurality of driving connecting rods and piston connecting rods to cooperate in pushing the piston to move, in the absence of a guide rod running through the piston cylinder, the error averaging principle is applied to reduce the eccentric movement of the piston caused by the single rod push, thereby improving the calibration accuracy.

[0082] (2) By arranging the piston cylinder and the ball screw in parallel up and down, the footprint is greatly reduced and the machine can be installed on a smaller mobile platform, making calibration work easier.

[0083] (3) Through the ball screw and linear bearing with balls, on the one hand, the axial load is transmitted in a rolling manner, which has small friction resistance, higher transmission efficiency, and faster start and stop, so that the breathing simulation device can output data that better fits the standard breathing waveform; on the other hand, several balls directly bear the load, reducing the movement deviation caused by the weight of the device itself. At the same time, the application of the error averaging effect can reduce the errors caused by inaccurate manufacturing and installation, deformation during operation, etc.

[0084] (4) By sampling the actual output flow rate, a mathematical model is established inside the piston cylinder, and the displacement and speed of the piston can be compensated in subsequent use. Furthermore, the pressure inside the piston cylinder in a sealed state is read and the sealing of the piston cylinder is automatically detected.

[0085] (5) A mathematical model is established by considering the compressibility of the gas and the size of the piston cylinder. This mathematical model can be selectively applied to breathing simulation devices of various sizes. In the case of existing devices, the actual required operating speed of the piston can be obtained by the required gas flow output, further improving the accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 A schematic structural diagram of a breathing simulation system for calibrating a pulmonary function instrument provided by the present invention.

[0087] Figure 2 A cross-sectional schematic diagram of a breathing simulation system for calibrating a pulmonary function instrument provided by the present invention.

[0088] Figure 3 It is a schematic diagram of the framework of the present invention.

[0089] Figure 4 The mathematical model established for the present invention is solved by MATLAB under the conditions of setting the piston to have a peak value of 0.5 m / s, a period of 3 s, a piston cross-sectional area of ​​0.038 square meters, and an output port of 0.00018 square meters.

[0090] Figure 5 The mathematical model established for the present invention is a MATLAB simulation result under the setting of a piston peak of 0.35 m / s, a period of 2.37 s, a piston cross-sectional area of ​​0.038 square meters, and an output port of 0.00018 square meters.

[0091] Figure 6 The mathematical model for the present invention is established by using the anasys fluent simulation results under the setting of the piston with a peak value of 0.35 m / s, a period of 2.37 s, a piston cross-sectional area of ​​0.038 square meters, and an output port of 0.00018 square meters.

[0092] In the figure, the outlet panel 101, the front end plate 102, the piston cylinder 103, the piston 104, the rear end plate 105, the vent 106, the linear bearing 107, the piston connecting rod 108, the nut 109, the connecting panel 110, the nut 111, the driving connecting rod 112, the linear bearing 113, the servo motor 114, the coupling 115, the first limiter 116, the ball screw 117, the slide 118, the driving panel 119, the nut 120, the second limiter 121, the bottom plate 122, the round hole 123, and the output port 124. DETAILED DESCRIPTION

[0093] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0094] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0095] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0096] Example 1

[0097] like Figure 1-3As shown, a breathing simulation system for calibrating a spirometer includes a mechanical system, which includes a piston cylinder, a connecting device, and a driving device. The piston cylinder includes an outlet panel 101, a front end plate 102, a piston cylinder 103, a piston 104, a rear end plate 105, and a bottom plate 122. The piston 104 is axially movable in the piston cylinder 103. The front end plate 102 and the rear end plate 105 are assembled at the axial ends of the piston cylinder 103. The bottom plate 122 is suitable for supporting the front end plate 102 and the rear end plate 105. The outlet panel 101 is installed on the front end plate 102. The outlet panel 101 is processed to form an output port 124. The front end plate 102 is processed to form a circular hole 123 suitable for connecting the piston cylinder 103 and the output port 124. The rear end plate 105 is processed to form two vents 106 suitable for connecting the piston cylinder 103 with the external environment. The bottom plate 122 is suitable for being detachably installed on a movable platform and an immovable platform. The driving device includes a servo motor 114, a ball screw 117, a slide 118, a first stopper 116, a second stopper 121, and a coupling 115. The connecting device includes two piston connecting rods 108, two driving connecting rods 112, a connecting panel 110, and a driving panel 119. The connecting panel 110 is arranged on the outer side of the rear end plate 105, and the driving panel 119 is fixedly arranged on the slide 118. The driving connecting rod 112 is suitable for connecting the driving panel 119 and the connecting panel 110. The piston connecting rod 108 is suitable for connecting the connecting panel 110 and the piston 104. The servo motor 114 is connected to the ball screw 117 through the coupling 115 and drives the slide 118 to reciprocate, and then drives the piston 104 to reciprocate through the connecting device to simulate human breathing.

[0098] In this embodiment, the piston cylinder 103 includes a first axis extending along its axial direction, the first axis is perpendicular to the front end plate 102 and the rear end plate 105, the first axis is parallel to the bottom plate 122, the first axis is suitable for passing through the center points of the two ends of the piston cylinder 103, the center of the circular hole 123 and the center of the piston 104, and the vent holes 106 are symmetrically arranged about the first axis. A 0°-180° line is defined, the 0°-180° line is perpendicular to the first axis and coplanar, and the two vent holes 106 are located on the 90°-270° line. The outlet panel 101 includes a second axis extending along its axial direction, the second axis is suitable for passing through the center of the output hole 124, and the first axis coincides with the second axis.

[0099] In this embodiment, the rear end plate 105 includes a plurality of through holes arranged in the middle or upper part thereof, and a linear bearing 107 suitable for supporting the piston connecting rod 108 or the driving connecting rod 112 is installed in the through hole. The linear bearing 107 includes a bearing sleeve and a plurality of balls fastened and assembled in the through hole, and the balls are suitable for supporting the piston connecting rod 108 or the driving connecting rod 112 and transmitting axial load. The piston connecting rod 108 is arranged symmetrically about the first axial direction, and the piston connecting rod 108 is arranged perpendicular to the piston 104 and the connecting panel 110, and one end of the piston connecting rod 108 is fixedly connected to the piston 104, and the other end of the piston connecting rod 108 is fixed to the connecting panel 110 through the first nut 109. By using the ball screw 117 and the linear bearing 107 as transmission components, on the one hand, the ball transmits the axial load in a rolling manner, which has less friction resistance, higher transmission efficiency, faster start and stop than the sliding screw, making the axial movement of the piston 104 more accurate, so that the pulmonary function instrument calibration device can output data that better fits the standard breathing waveform; on the other hand, a number of balls directly bear the load, reducing the movement deviation caused by the weight of the device itself, and at the same time, the error averaging effect can reduce the deviation caused by inaccurate manufacturing and installation, deformation during operation or thermal expansion, etc., and mitigate impact and vibration, thereby reducing the cylinder deviation movement of the piston 104. The drive connecting rod 112 is arranged symmetrically on the left and right, and the drive connecting rod 112 is arranged perpendicular to the drive panel 119 and the connection panel 110. One end of the drive connecting rod 112 is fixed to the connection panel 110 through the nut 109, and the other end of the drive connecting rod 112 is fixed to the drive panel 119 through the nut 120.

[0100] In this embodiment, the driving device further includes stoppers arranged at both axial ends adjacent to the ball screw 117, and the stoppers include a first stopper 116 arranged adjacent to the rear end plate 105 and a second stopper 121 arranged adjacent to the front end plate 102, and the stoppers are suitable for limiting the range of motion of the slide 118, thereby limiting the range of motion of the piston 104, and the lower ends of the front end plate 102 and the rear end plate 105 are assembled at both axial ends of the bottom plate 122 and enclosed to form an installation space suitable for accommodating the driving device, and the driving device is packaged and fixed to the bottom plate 122 after assembly. The rear end plate 105 includes a square opening arranged at its lower end, and the servo motor 114 is embedded in the square opening.

[0101] In this embodiment, the breathing simulation system also includes a control system, which includes a controller and a computer. The computer is suitable for writing a control program through software, establishing a standard breathing model according to a standard breathing curve, setting a number of calibration parameters and calculating motion compensation. The controller includes a driver and a PLC suitable for bidirectional connection to the servo motor 114. The PLC includes a command conversion module suitable for bidirectional connection to the computer, a drive module suitable for bidirectional connection to the driver, and modules corresponding to a temperature transmitter, a humidity transmitter, a pressure transmitter, a cylinder pressure transmitter, and a flow measurement device.

[0102] The process of the computer issuing a motion command to the servo motor 114 is as follows: the command conversion module is suitable for converting the motion command output by the computer into a drive command and transmitting it to the driver through the drive module, and the driver then converts the drive command into an electrical signal to drive the servo motor 114 to work.

[0103] The process of the servo motor 114 feeding back its own state to the computer is as follows: the servo motor 114 can also feed back the electrical signal reflecting its own motion state to the driver, the driver converts the electrical signal into a state feedback signal and provides it to the command conversion module through the drive module, the command conversion module converts the state feedback signal and feeds it back to the computer, and the computer then compares the feedback signal with the standard breathing model and calibration parameters to calculate the motion compensation.

[0104] The computer turns on the temperature transmitter, pressure transmitter, and humidity transmitter according to the calibration requirements. The temperature transmitter, pressure transmitter, and humidity transmitter transmit industrial standard electrical signals to the controller. The controller converts the industrial standard electrical signals and feeds them back to the computer, so that the computer obtains the temperature, pressure, and humidity parameters, thereby converting the gas volume of the output gas of the breathing simulation system between room temperature conditions (ATP) and human body conditions (BTPS). Specifically: the temperature condition of BTPS is 37°C, the pressure condition is ambient pressure, and the humidity condition is 100%; the temperature condition of ATP is ambient temperature, the pressure condition is ambient pressure, and the humidity condition is ambient humidity. Start the temperature transmitter, humidity transmitter, and pressure transmitter to obtain the temperature, humidity, and pressure of the environment, and use Obtain the volume conversion factor to obtain the corrected gas volume.

[0105] Example 2

[0106] A compensation method for a breathing simulation system, which is suitable for calibrating and compensating the above breathing simulation system, comprises the following steps:

[0107] 1. Check the air tightness of the piston cylinder as follows:

[0108] 1-1 Let the position of the piston 104 when the slide 118 abuts against the first stopper 116 be the starting point, and the position of the piston 104 when the slide 118 abuts against the second stopper 121 be the end point. The direction from the starting point to the end point is the positive direction of the x-axis. The total stroke is L. The total stroke L is evenly divided into n sub-strokes. The length of the sub-stroke is Let the position of each segment point be x i , x n coincides with the end point of the trip;

[0109] 1-2 Seal the front output port 124 of the piston cylinder, turn on the pressure transmitter in the cylinder and record the reading P0 at this time;

[0110] 1-3 The servo motor drives the piston 104 to move il, i∈[1,n]. The horizontal load capacity of the servo motor is F. Observe the pressure gauge reading P in the cylinder. i ;

[0111] 1-4 If P i If the pressure rises first and then falls, it is considered that the sealing performance of this section of the piston cylinder 103 is insufficient; if P i near It is necessary to unseal, depressurize, and then reseal and read P again. i This is used as the baseline value for the next stage and steps 1.1 to 1.3 are repeated.

[0112] 1-5 Repeat steps 1-1 to 1-4 to test the sealing performance of the piston cylinder 103 section by section.

[0113] 2. Model the piston cylinder 103 and obtain the compensation coefficient:

[0114] 2-1 The flow measurement device is connected to the breathing simulation system, the computer issues a command to the breathing simulation system and starts the flow measurement device at the same time, the servo motor 114 is suitable for driving the piston 104 to move to the first stopper 116 and to the second stopper 121 at a speed v0, which is a stroke L. The flow measurement device measures the output flow Q(t) of the breathing simulation device during this process.

[0115] 2-2 The corresponding relationship between x and Q(t), i.e., Q(x), is obtained through x=v0t, where x is the actual stroke position of the piston and A is the cross section of the piston cylinder. In theory, Q(x)=v0A is a constant value, but because there is an error and it is believed that it is mainly the processing error of the piston cylinder, Q(x) will fluctuate in reality;

[0116] The piston cylinder model is established, and in x∈[x i-1 ,x i ) is considered that the piston cross-sectional area is A i , Actual piston cylinder cross-sectional area A i The difference from the theoretical piston cylinder area A is ΔA i , i∈[1,n], and then we get A i The corresponding relationship with x and ΔA i Corresponding to x, that is ΔA(x i )=A(x i )-A, and A(x i ) is abbreviated as A i , ΔA(x i ) is abbreviated as ΔA i ;

[0117] 2-3 The running speed of the piston that needs to be compensated for each sub-stroke

[0118] 2-4 When the breathing simulation system performs other functions, input the set volume V and obtain the current piston position x, x∈[x n ,x n+1 ), when the piston 104 is set to move from the first stopper 116 to the second stopper 121, the volume margin V that the piston 104 can move is calculated 暂 =(x n+1 -x)A n+1 When the piston 104 is set to move from the second stopper 121 to the first stopper 116, the volume margin V of the piston 104 that can move is calculated 暂 =(xx n )A n+1 ;

[0119] 2-5 When the piston 104 is set to move from the first stopper 116 to the second stopper 121, the parameter j is initialized to 0, and the volume margin V is temporarily compared with the input volume V:

[0120] If V 暂 >V, then j=0,

[0121] If V 暂 <V, then j+1, and on the volume margin V 暂 =(x n+1 -x)A n+1 Plus the volume of the next interval

[0122] Compare it with V again, if it is less than V, continue to add until V 暂 >V, then determine the size of j;

[0123] If j = 1, then

[0124] If j≥2, change j-1, and we get:

[0125] 2-6 When the piston 104 is set to move from the second stopper 121 to the first stopper 116, first calculate the volume margin V of the current interval where the piston 104 is located 暂 =(xx n )A n+1 , initialize the parameter j to 0, and set the volume margin V 暂 Compare with input volume V;

[0126] If V 暂 >V, then j=0,

[0127] If V 暂 <V, then j+1, and on the volume margin V 暂 =(xx n )A n+1 Plus the volume of the next interval

[0128] Compare it with V again, if it is less than V, continue to add until V 暂 >V, then determine the size of j;

[0129] If j = 1, then

[0130] If j≥2, change j-1, and we get:

[0131] In summary, the piston movement distance and speed after compensation correction can be obtained.

[0132] 2. Model the piston cylinder to obtain the relationship between the piston 104 movement speed and the gas flow output

[0133] A mathematical model is established based on a one-dimensional steady adiabatic isentropic flow, and the relationship between the gas parameters in the piston cylinder 103, the gas flow output port parameters, and the stagnation state parameters are listed:

[0134] According to the law of conservation of energy:

[0135]

[0136] P r Stagnation state pressure

[0137] T r Stagnation temperature

[0138] ρ r Stasis state density

[0139] P1: Gas pressure in piston cylinder 103

[0140] T1: Gas temperature in piston cylinder 103

[0141] ρ1: Gas density in piston cylinder 103

[0142] A1: Piston 104 cross-sectional area

[0143] v1: Use piston 104 to move at a certain speed

[0144] P2: Gas flow output port 124 pressure

[0145] T2: Temperature of gas flow output port 124

[0146] ρ2: gas flow output 124 density

[0147] A2: Cross-sectional area of ​​air flow outlet 124

[0148] v2: Gas flow rate at the gas flow outlet 124, where k is the gas adiabatic coefficient. If the gas is air, k = 1.4. According to the ideal gas state equation:

[0149] P r =ρ r RT r ...(3)

[0150] P1=ρ1RT1...(4)

[0151] P2=ρ2RT2...(5)

[0152] R is the gas constant, the value is R = 287 (J / kg*K)

[0153] According to the isentropic relationship:

[0154]

[0155] From equations (2) to (6), we can get:

[0156]

[0157]

[0158] According to the law of conservation of mass:

[0159] Q m =ρ1v1A1=ρ2v2A2...(10)

[0160] Substituting (8)(9) into (10), we can obtain:

[0161]

[0162] The stagnation temperature T r , gas constant R, piston cross-sectional area A1, gas flow output cross-sectional area A2, and gas adiabatic coefficient k are all constants, and the relationship between the movement speed v1 of the piston 104 and the gas flow rate v2 of the gas flow output port 124 can be obtained.

[0163] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A breathing simulation system, characterized in that: Including mechanical systems and control systems, The mechanical system includes a piston cylinder, a connecting device and a driving device. The piston cylinder comprises a piston cylinder, a front end plate, a rear end plate, a bottom plate, a piston and an outlet panel, the piston can be movably arranged in the piston cylinder along the axial direction, the front end plate and the rear end plate are assembled at the axial ends of the piston cylinder, the bottom plate is suitable for supporting the front end plate and the rear end plate, the outlet panel is installed on the front end plate, the outlet panel is processed to form a circular vent hole, the front end plate is processed to form a front end vent hole suitable for connecting the piston cylinder with the circular vent hole, the rear end plate is processed to form a plurality of rear end vent holes suitable for connecting the piston cylinder with the external environment, and the bottom plate is suitable for being detachably installed on a movable platform and an immovable platform; The driving device includes a servo motor, a ball screw, a slide, a first limiter and a second limiter. The servo motor is connected to the ball screw through a coupling, thereby driving the slide to perform reciprocating linear motion. The first limiter and the second limiter are respectively arranged adjacent to the axial ends of the ball screw. The first limiter and the second limiter are suitable for limiting the motion range of the slide, thereby limiting the motion range of the piston. The connecting device includes a plurality of piston connecting rods, a plurality of driving connecting rods, a connecting panel and a driving panel, wherein the connecting panel is arranged on the outer side of the rear end plate, the driving panel is fixedly arranged on the slide, the driving connecting rod is suitable for connecting the driving panel and the connecting panel, the piston connecting rod is suitable for connecting the connecting panel and the piston, the servo motor drives the slide to reciprocate through the ball screw, and then drives the piston to reciprocate through the connecting device to simulate human breathing; The control system includes a controller, a computer, a temperature transmitter and pressure transmitters respectively arranged inside and outside the piston cylinder. The computer is suitable for writing a control program through software, establishing a standard breathing model according to a standard breathing curve, setting a number of calibration parameters and calculating motion compensation. The controller is bidirectionally connected to the servo motor, the computer, the temperature transmitter and the pressure transmitter to form a closed loop.

2. A breathing simulation system according to claim 1, characterized in that: The piston cylinder includes a first axis extending along its axial direction, the first axis is perpendicular to the front end plate and the rear end plate, the first axis is parallel to the bottom plate, the first axis is suitable for passing through the center points of both ends of the piston cylinder, the center of the front end vent hole and the center of the piston, and the rear end vent hole is symmetrically arranged about the first axis; The outlet panel includes a second axis extending along the axial direction thereof, the second axis is adapted to pass through the center of the circular vent hole, and the first axis coincides with the second axis.

3. A breathing simulation system according to claim 2, characterized in that: The piston connecting rod is arranged symmetrically on both sides, the piston connecting rod is arranged perpendicular to the piston and the connecting panel, one end of the piston connecting rod is fixedly connected to the piston or formed integrally, and the other end of the piston connecting rod is fixed to the connecting panel through a first nut; The driving connecting rod is arranged symmetrically on the left and right, and is arranged perpendicular to the driving panel and the connecting panel. One end of the driving connecting rod is fixed to the connecting panel through a first nut, and the other end of the driving connecting rod is fixed to the driving panel through a second nut.

4. A breathing simulation system according to claim 3, characterized in that: The rear end plate includes a plurality of through holes arranged in the middle or upper part thereof, and linear bearings are installed in the through holes. The linear bearings include bearing sleeves and a plurality of balls which are fastened and assembled in the through holes. The balls are suitable for supporting the piston connecting rod or the driving connecting rod and transmitting axial loads.

5. A breathing simulation system according to claim 4, characterized in that: The lower end of the front end plate and the lower end of the rear end plate are assembled at the axial ends of the bottom plate and enclose to form an installation space suitable for accommodating the driving device. After the driving device is assembled, it is packaged and fixed to the bottom plate.

6. A breathing simulation system according to claim 5, characterized in that: The ball screw includes a screw, a screw nut and a ball. The screw is a threaded shaft with a semicircular spiral groove. The inner wall of the screw nut is processed with a semicircular spiral groove. The screw and the semicircular spiral groove on the screw nut are combined to form a spiral raceway with a circular cross-section. The ball rolls along the spiral raceway. The slide is fixedly installed on the screw nut. The output shaft of the servo motor drives the screw to rotate through the coupling. The ball rolls forward in the spiral raceway, thereby driving the screw nut and the slide to perform linear motion.

7. A breathing simulation system according to claim 1, characterized in that: The controller comprises a driver and a PLC adapted to bidirectionally connect to the servo motor, the PLC comprises a command conversion module adapted to bidirectionally connect to the computer and a drive module adapted to bidirectionally connect to the driver, and the command conversion module is bidirectionally connected to the drive module; The process of the computer issuing a motion command to the servo motor is as follows: the command conversion module is adapted to convert the motion command output by the computer into a drive command and transmit it to the driver through the drive module, and the driver then converts the drive command into an electrical signal to drive the servo motor to work; The process of the servo motor feeding back its own state to the computer is as follows: the servo motor can also feed back an electrical signal reflecting its own motion state to the driver, the driver converts the electrical signal into a state feedback signal and provides it to the command conversion module through the drive module, the command conversion module converts the state feedback signal and feeds it back to the computer, and the computer then compares the fed-back signal with the standard breathing model and calibration parameters to calculate motion compensation.

8. A breathing simulation system according to claim 7, characterized in that: The control system includes a temperature transmitter and a pressure transmitter installed on the outlet panel, the PLC includes a pressure module and a temperature module, the pressure module is bidirectionally connected to the pressure transmitter and the command conversion module respectively, and the temperature module is bidirectionally connected to the temperature transmitter and the command conversion module respectively; The process of the computer issuing a switch command to the temperature transmitter and the pressure transmitter according to the calibration requirements is as follows: the command conversion module is adapted to convert the switch command output by the computer into a switch instruction and transmit it to the temperature module and the pressure module, thereby controlling the opening or closing of the temperature transmitter and the pressure transmitter through the temperature module and the pressure module; The process by which the computer obtains temperature and pressure parameters from the temperature transmitter and the pressure transmitter according to calibration requirements is as follows: the temperature transmitter and the pressure transmitter transmit industrial standard electrical signals to the temperature module and the pressure module, and the command conversion module converts the industrial standard electrical signals and feeds them back to the computer, so that the computer obtains temperature and pressure parameters, thereby performing gas volume conversion between room temperature conditions (ATP) and human body conditions (BTPS) for the input and output gases of the breathing simulation system.

9. A compensation method for a breathing simulation system, characterized in that: It is suitable for calibrating and compensating a breathing simulation system as described in any one of rights 1 to 8, comprising the following steps:

1. Check the air tightness of the piston cylinder; 2. Model the piston cylinder and obtain the compensation coefficient: 2-1 Connecting the flow measurement device to the breathing simulation system, the computer issues a command to the breathing simulation system and simultaneously starts the flow measurement device, the servo motor is suitable for driving the piston to complete a uniform motion of a stroke L at a speed v0, and the flow measurement device measures the output flow Q(t) of the breathing simulation system during this process; 2-2 The corresponding relationship between x and Q(t) is obtained through x=v0t, that is, Q(t)=xA=v0At, Q(x)=v0A, x is the actual stroke position of the piston, and A is the cross-sectional area of ​​the piston cylinder; The piston cylinder model is established, and in x∈[x i-1 ,x i ) is considered that the piston cross-sectional area is A i , Actual piston cylinder cross-sectional area A i The difference from the theoretical piston cylinder area A0 is ΔA i , i∈[1,n], and then we get A i The corresponding relationship with x and ΔA i Corresponding to x, that is, ΔA(x i )=A(x i )-A0, and A(x i ) is abbreviated as A i , ΔA(x i ) is abbreviated as ΔA i , the piston needs to compensate for the running speed of each sub-stroke 2-4 When the volume V of gas needs to be input, obtain the current piston position x, x∈[x n ,x n+1 ), when the piston is set to move from the first stopper to the second stopper, calculate the volume margin V of the piston 暂 =(x n+1 -x)A n+1 When the piston is set to move from the second stopper to the first stopper, calculate the volume margin V of the piston that can move 暂 =(xx n )A n+1 ; 2-5 When the piston is set to move from the first stopper to the second stopper, the parameter j is initialized to 0 and the volume margin V is 暂 Compare with the input volume V: If V 暂 >V, then j=0, If V 暂 <V and on volume margin V 暂 =(x n+1 -x)A n+1 Plus the volume of the next interval Rear V 暂 >V, Then j = 1, If V 暂 <V and on volume margin V 暂 =(x n+1 -x)A n+1 Plus the volumes of at least two intervals Rear V 暂 >V, Then j≥2, 2-6 When the piston is set to move from the second stopper to the first stopper, the parameter j is initialized to 0 and the volume margin V is 暂 Compare with the input volume V: If V 暂 >V, then j=0, If V 暂 <V, then j+1, and on the volume margin V 暂 =(xx n )A n+1 Plus the volume of the next interval Compare it with V again, if it is less than V, continue to add until V 暂 >V, then determine the size of j; If j = 1, then If j≥2, change j-1, and we get:

10. The compensation method of the breathing simulation system according to claim 9, characterized in that: Also includes 3. Model the piston cylinder to obtain the compression compensation coefficient, that is, the coefficient of relationship between the piston movement speed and the gas flow output: A mathematical model is established based on the one-dimensional steady adiabatic isentropic flow, and the relationship between the gas parameters in the piston cylinder, the gas flow output port parameters, and the stagnation state parameters are listed: According to the law of conservation of energy: P r Stagnation state pressure T r Stagnation temperature ρ r Stasis state density P1: Gas pressure in piston cylinder T1: Gas temperature in piston cylinder ρ1: Gas density in piston cylinder A1: Piston cross-sectional area v1: Use piston movement speed P2: Gas flow output pressure T2: Gas flow output temperature ρ2: Gas flow output density A2: Cross-sectional area of ​​air flow output port v2: Gas flow rate at the gas flow output port Where k is the gas insulation coefficient. If the gas is air, k = 1.4 According to the ideal gas state equation: P r =ρ r RT r ... (3) P1=ρ1RT1... (4) P2=ρ2RT2... (5) R is the gas constant, the value is R = 287 (J / kg*K) According to the isentropic relationship: From equations (2) to (6), we can get: According to the law of conservation of mass: Q m =ρ1v1A1=ρ2v2A2... (10) Substituting (8)(9) into (10), we can obtain: Among them, the stagnation temperature T r , gas constant R, piston cross-sectional area A1, gas flow output cross-sectional area A2, and gas adiabatic coefficient k are all constants, and compensation operation is performed according to the relationship between the piston movement speed v1 and the gas flow rate v2 at the gas flow output port. The gas flow rate v2 at the gas flow output port is set according to the simulation needs to obtain the piston movement speed v1 required by the piston.

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