阅读说明：本技术 呼吸机压力维持装置 (Pressure maintaining device of breathing machine ) 是由 敖伟 李秋华 罗小锁 于 2018-12-10 设计创作，主要内容包括：本申请涉及一种呼吸机压力维持装置,包括：氧气源、压缩空气源和空氧混合器；所述氧气源与所述空氧混合器之间通过所述连通管道连接氧气流量控制阀,所述氧气流量控制阀用于在氧气流量控制信号u<Sub>eo</Sub>的作用下,控制所述呼吸机压力维持装置中的氧气流量；所述压缩空气源与所述空氧混合器之间通过所述连通管道连接空气流量控制阀,所述空气流量控制阀用于在空气流量控制信号u<Sub>ea</Sub>的作用下,控制所述呼吸机压力维持装置中的空气流量,上述呼吸机压力维持装置可以保证压力和氧气浓度的同步调节,从而确保呼吸机的临床使用效果。(The application relates to a pressure maintenance device of a breathing machine, comprising: an oxygen source, a compressed air source and an air-oxygen mixer; the oxygen source and the air-oxygen mixer are connected with an oxygen flow control valve through the communication pipeline, and the oxygen flow control valve is used for controlling the signal u of oxygen flow eo Under the action of the oxygen control device, controlling the oxygen flow in the pressure maintaining device of the respirator; the air flow control valve is connected between the compressed air source and the air-oxygen mixer through the communication pipeline and used for controlling a signal u according to the air flow ea Under the action of the pressure sensor, the pressure of the breathing machine is controlledThe pressure maintaining device of the breathing machine can ensure the synchronous regulation of pressure and oxygen concentration, thereby ensuring the clinical use effect of the breathing machine.)

1. A ventilator pressure maintenance device, comprising:

the device comprises an oxygen source, a compressed air source, an air-oxygen mixer and a calculating unit;

the oxygen source and the compressed air source are respectively communicated with the air-oxygen mixer through communicating pipelines;

the oxygen source and the air-oxygen mixer are connected with an oxygen flow control valve through the communication pipeline, and the oxygen flow control valve is used for controlling the signal u of oxygen flow_eoUnder the action of the oxygen control device, controlling the oxygen flow in the pressure maintaining device of the respirator;

the air flow control valve is connected between the compressed air source and the air-oxygen mixer through the communication pipeline and used for controlling a signal u according to the air flow_eaControlling the air flow in the ventilator pressure maintenance device;

the air-oxygen mixer is connected with an air flow control valve which is used for controlling a flow control signal u in the air-oxygen mixing process_eUnder the action of the pressure control device, controlling the pressure value of the pressure maintaining device of the respirator;

the computing unit is to:

the dynamic parameters of the respiratory process are identified on line, and the linear gas path damping coefficients are respectively calculated

According to the damping coefficient of the linear gas pathAnd the linearized dynamic coefficient of downdraftPerforming adaptive parameters

incorporating the adaptive parameter

incorporating the adaptive parameter

2. The ventilator pressure maintenance device of claim 1 wherein a linearized airway damping coefficient is calculatedAnd linearized dynamic coefficient of aerationThe method comprises the following steps:

modeling a breathing process to obtain a breathing model;

presetting and measuring intermediate parameter values;

calculating the linear gas path damping coefficient according to the breathing model and the intermediate parameter value

3. The ventilator pressure maintenance device of claim 2 wherein said deriving a breathing model comprises:

modeling a respiratory process to obtain a respiratory process linear model;

rewriting the linear model of the respiratory process into a continuous transfer function;

and carrying out discretization processing on the continuous transfer function to obtain the breathing model.

4. The ventilator pressure maintenance device of claim 2 wherein said presetting and measuring intermediate parameter values comprises:

presetting an air-oxygen mixing expected pressure value P_dMeasuring the actual air-oxygen mixed pressure value P_awAnd calculating the pressure error e_p＝P_aw-P_d；

Continuously measuring the air-oxygen mixed pressure value P twice_aw(k)、P_aw(k-1) and air-oxygen mixture flow values F (k), F (k-1);

respectively calculating the air-oxygen mixed pressure difference value P_Δ(k)＝P_aw(k)-P_aw(k-1) and the air-oxygen mixed flow value twice in succession^T(k)＝[F(k) F(k-1)]。

5. The ventilator pressure maintenance device of claim 4 wherein said pressure is dependent upon said breathModel and the intermediate parameter value, and calculating the linear gas path damping coefficient

according to said pressure difference P_Δ(k) And the air-oxygen mixed flow value (k) is obtained twice continuously, and parameter recursion is carried out by combining the iterative least square method, so that the parameter value theta to be estimated is estimated^T(k)；

According to the parameter value theta to be estimated^T(k) Calculating the linear gas path damping coefficientAnd linearized dynamic coefficient of aeration

6. The ventilator pressure maintenance device of claim 5 wherein said linearization circuit damping factor is based onAnd the linearized dynamic coefficient of downdraftPerforming adaptive parameters

according to the damping coefficient of the linear gas pathAnd the linearized dynamic coefficient of downdraft

According to the upper limit value of the linear gas path damping coefficient and the linear dynamic favorable gas coefficient And lower limit valueEstimating adaptive parameters

7. The ventilator pressure maintenance device of claim 5 in combination with said adaptive parameter

according to said pressure error e_pDesign feedback gain k₀e_P；

According to the feedback gain k₀e_PAnd the adaptive estimation parameterCalculating the air-oxygen mixed flow control signal u_eTo achieve pressure adaptive control.

8. The ventilator pressure maintenance device of claim 7 in combination with said adaptive parameterCalculating air flow control signals u separately_eaAnd an oxygen flow control signal u_eoThe method comprises the following steps:

calculating the desired air ratio S according to the preset oxygen concentration S_aAnd the desired oxygen ratio S_o；

According to the desired air ratio S_aAnd the desired oxygen ratio S_oCalculating the air flow control signal u_eaAnd said oxygen flow control signal u_eoTo achieve adaptive control of oxygen concentration.

9. The pressure maintenance apparatus of claim 8 wherein the desired air ratio S is calculated as a function of a predetermined oxygen concentration S_aAnd the desired oxygen ratio S_oThe method comprises the following steps:

calculating the expected air proportion S according to the preset oxygen concentration S in combination with the fixed ratio of air and oxygen_aAnd the desired oxygen ratio S_o。

10. The ventilator pressure maintenance device of claim 8 wherein said ratio is dependent upon said desired air ratio S_aAnd the desired oxygen ratio S_oCalculating said air flow control signal u_eaAnd said oxygen flow control signal u_eoThe method comprises the following steps:

according to the desired air ratio S_aAnd the desired oxygen ratio S_oAnd the feedback gain k₀e_PAnd the adaptive estimationParameter(s)

Technical Field

The application relates to the technical field of medical equipment control, in particular to a pressure maintaining device of a breathing machine.

Background

For ventilators, the accuracy and stability of oxygen concentration and pressure maintenance are the most central and fundamental requirements. Since the oxygen concentration and pressure maintenance are different from the targets of interest, and both air and oxygen flow rates need to be controlled. Therefore, if the controller is not stable enough or the device performance changes after long-term use, the clinical use effect of the breathing machine is affected.

Currently, ventilator pressure and oxygen concentration maintenance are typically separate designs. The pressure during the maintenance of the oxygen concentration may not be able to meet the use requirements. While the related designs can maintain the respiratory process pressure, the synchronous regulation of oxygen concentration typically requires additional modules to ensure, adding to the complexity of the ventilator.

Disclosure of Invention

In view of the above, there is a need to provide a ventilator pressure maintenance device that addresses the problem of the inability of existing methods to control both pressure and oxygen concentration.

A ventilator pressure maintenance device comprising:

the device comprises an oxygen source, a compressed air source, an air-oxygen mixer and a calculating unit;

the oxygen source and the compressed air source are respectively communicated with the air-oxygen mixer through communicating pipelines;

the oxygen source and the air-oxygen mixer are connected with an oxygen flow control valve through the communication pipeline, and the oxygen flow control valve is used for controlling the flow of oxygenNumber u_eoUnder the action of the oxygen control device, controlling the oxygen flow in the pressure maintaining device of the respirator;

the air flow control valve is connected between the compressed air source and the air-oxygen mixer through the communication pipeline and used for controlling a signal u according to the air flow_eaControlling the air flow in the ventilator pressure maintenance device;

the air-oxygen mixer is connected with an air flow control valve which is used for controlling a flow control signal u in the air-oxygen mixing process_eUnder the action of the pressure control device, controlling the pressure value of the pressure maintaining device of the respirator;

the computing unit is to:

the dynamic parameters of the respiratory process are identified on line, and the linear gas path damping coefficients are respectively calculated

And linearized dynamic coefficient of aeration

According to the damping coefficient of the linear gas pathAnd the linearized dynamic coefficient of downdraft

Performing adaptive parameters

Estimating;

incorporating the adaptive parameterCalculating air-oxygen mixed flow control signal u_eTo achieve pressure adaptive control;

incorporating the adaptive parameterCalculating air flow control signals u separately_eaAnd an oxygen flow control signal u_eoTo achieve adaptive control of oxygen concentration.

The pressure maintaining device of the breathing machine synchronously designs the pressure maintaining process and the oxygen concentration maintaining process. Calculating the linear gas path damping coefficient by on-line identifying the dynamic parameters of the respiratory process

And linearized dynamic coefficient of aerationAccording to the damping coefficient of the linear gas path

And the linearized dynamic coefficient of downdraftPerforming adaptive parametersAnd (6) estimating. Combining adaptive parameters

Obtaining the air-oxygen mixed flow control signal u_eThe air flow control signal u_eaAnd said oxygen flow control signal u_eo. By said air-oxygen mixed flow control signal u_eThe control pressure is adaptively changed and is controlled by the air flow control signal u_eaAnd said oxygen flow control signal u_eoAnd controlling the oxygen concentration to change adaptively. The synchronous regulation of pressure and oxygen concentration can be ensured without increasing the complexity of the breathing machine, thereby ensuring the clinical use effect of the breathing machine.

Drawings

FIG. 1 is a schematic diagram of a ventilator pressure maintenance device with compressed air and oxygen sources according to an embodiment of the present disclosure;

FIG. 2 is a flow chart of a method for adaptive pressure and oxygen concentration control according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a method for controlling a pressure maintenance device of a ventilator with compressed air and oxygen sources according to an embodiment of the present disclosure;

FIG. 4 is a flow chart of another adaptive pressure and oxygen concentration control method provided in an embodiment of the present application;

FIG. 5 is a schematic diagram illustrating an embodiment of the present disclosure for online identification of respiratory process kinetic parameters and calculation of linear gas path damping coefficients

And linearized dynamic coefficient of aerationA flow chart of (1);

FIG. 6 is a block diagram of an embodiment of the present application, illustrating a method for combining the adaptive parameters

Calculating air flow control signals u separately_eaAnd an oxygen flow control signal u_eoTo implement a flow chart for adaptive control of oxygen concentration.

Description of the reference numerals

100 pressure maintaining device of breathing machine

110 oxygen source

120 compressed air source

130 connecting pipe

140 air-oxygen mixer

151 oxygen pressure stabilizing valve

152 air pressure maintaining valve

161 oxygen flow control valve

162 air flow control valve

163 air oxygen flow control valve

171 oxygen flow sensor

172 air flow sensor

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and it is therefore not intended to be limited to the embodiments disclosed below.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, a ventilator pressure maintenance device 100 with compressed air and oxygen sources is provided. The pressure maintenance device 100 with compressed air and oxygen source includes an oxygen source 110 and a compressed air source 120. The oxygen source 110 and the compressed air source 120 are respectively connected to an air-oxygen mixer 140 through a communication pipe 130. The oxygen source 110 is connected to the oxygen pressure maintaining valve 151, the oxygen flow control valve 161 and the oxygen flow sensor 171 sequentially through the communication pipe 130. The compressed air source 120 is connected to the air pressure maintaining valve 152, the air flow control valve 162, and the air flow sensor 172 through the communication pipe 130 in sequence. The air-oxygen mixer 140 is also connected to an air-oxygen flow control valve 163. The oxygen flow control valve 161, the air flow control valve 162, and the air oxygen flow control valve 163 may be controlled by adopting an adaptive pressure and oxygen concentration control method. It is understood that the oxygen concentration in the ventilator pressure maintenance device 100 can be controlled by controlling the oxygen flow control valve 161 and the air flow control valve 162. By controlling the air oxygen flow control valve 163, the pressure value of the ventilator pressure maintenance device 100 can be controlled.

Referring to fig. 2, the adaptive pressure and oxygen concentration control method includes:

s10, carrying out on-line identification on the dynamic parameters of the respiratory process, and respectively calculating the linear gas path damping coefficientsAnd linearized dynamic coefficient of aeration

In step S10, the breathing process is modeled to obtain a linear model of the breathing process. Presetting and measuring required parameter values in the linear model in the process of deforming the linear model. Calculating to obtain the linear gas path damping coefficient according to the linear model and the related parameter valuesAnd the linearized dynamic coefficient of downdraft

And realizing the online identification process of the dynamic parameters of the respiratory process.

S20, according to the linear gas path damping coefficientAnd the linearized dynamic coefficient of downdraftPerforming adaptive parameters

And (6) estimating. In step S20, since the actual parameters of the system vary within a certain range, and the range of variation is related to the fit of the ventilator and the patient, that is, the parameter adaptive process has a very close relationship to the effect of the ventilator application. Therefore, the parameter is identifiedFor parameter estimation by adapting the projection parameters to the linearized gas path damping coefficients

And the linearized dynamic coefficient of downdraftIn combination, the adaptive parameters can be implementedIs estimated. By said adaptive parameterAdaptive control of pressure and oxygen concentration in the ventilator may be achieved.

S30, combining the adaptive parameters

Calculating air-oxygen mixed flow control signal u_eTo achieve pressure adaptive control. In the step S30, the flow control signal u is mixed by the air and oxygen_eActs on the air-oxygen flow control valve 163 to control the pressure variation of the air-oxygen mixer 140. Due to the adaptive parametersCan be changed according to actual conditions, thereby ensuring the self-adaptive change of the air pressure of the air-oxygen mixer 140 in the pressure maintenance device 100 of the respirator. The process is simple and easy to implement, and the complexity of the breathing machine is not required to be increased, so that the self-adaptive control of the pressure in the clinical use process of the breathing machine is ensured.

S40, combining the adaptive parametersCalculating air flow control signals u separately_eaAnd an oxygen flow control signal u_eoTo achieve adaptive control of oxygen concentration. In the stepIn step S40, the air flow control signal u is used_eaAnd said oxygen flow control signal u_eoRespectively act on the air flow control valve 162 and the oxygen flow control valve 161, so as to control the flow of air and oxygen in the ventilator pressure maintenance device 100, and thus the oxygen concentration. According to the adaptive parameterAdaptive variation of oxygen concentration in the ventilator pressure maintenance device 100 may be achieved. The process is simple and easy to implement, and the complexity of the breathing machine is not required to be increased, so that the self-adaptive control of the oxygen concentration in the clinical use process of the breathing machine is ensured.

The self-adaptive pressure and oxygen concentration control method carries out synchronous centralized design on a pressure maintaining process and an oxygen concentration maintaining process, and brings the characteristics of the two processes into the control signal design. In actual use, as the device ages, the temperature changes and the humidity changes, the performance and the characteristics of parts of the breathing machine change along with the aging. The control signal is adjusted by the self-adaptive pressure and oxygen concentration control method, so that the accuracy and stability of the control effect can be ensured under the condition that a device or the environment is changed. The self-adaptive pressure and oxygen concentration control method is simple and easy to implement, and can ensure synchronous regulation of pressure and oxygen concentration without increasing the complexity of the breathing machine, thereby ensuring the clinical use effect of the breathing machine. In addition, the inferior position of traditional breathing machine pressure control and oxygen concentration maintenance separation design has been overcome in this application, makes the pressure and the oxygen concentration of air-oxygen mixer realize keeping in step, and simultaneously, the device's simple structure, easily integrated, software and hardware highly complex characteristics for upgrade and maintenance convenience, swift. In addition, due to the functions of parameter online estimation and control signal self-adaptive adjustment, the method and the device can adapt to the change of the use environment and the aging stability of devices, improve the reliability and the service life of the product, and simultaneously can keep good clinical use effect.

Referring to fig. 3, the adaptive pressure and oxygen concentration control methodActing on the ventilator pressure maintenance device 100 with the compressed air and oxygen source. Firstly presetting an air-oxygen mixing expected pressure value P_dCombined with the actual air-oxygen mixture pressure value P_awCalculating the difference to obtain a pressure error value e_p. Performing parameter identification and self-adaptive control according to the pressure self-adaptive adjustment process to obtain an air-oxygen mixed flow control signal u_eThereby realizing the self-adaptive control of the pressure. In order to maintain the oxygen concentration of the air-oxygen mixing chamber 140, a flow distribution calculation is performed by using a preset oxygen concentration S, and the desired air ratios S are obtained respectively_aAnd the desired oxygen ratio S_o. The air-oxygen mixed flow control signal u obtained by combining calculation_eAnd the actual oxygen flow and air flow of the air-oxygen mixing chamber 140 measured by the oxygen flow sensor 171 and the air flow sensor 172 are used, respectively. Subsequently calculating said desired air flow u_eaAnd the desired oxygen flow u_eoRespectively, difference from the actual value. According to the parameter adaptive adjustment process, the flow rates of air and oxygen are respectively brought to or close to the desired flow rates by the air flow control valve 162 and the oxygen flow control valve 161. The air and oxygen gas after the adaptive tuning process are mixed in the air-oxygen mixing chamber 140, thereby controlling the oxygen concentration. Therefore, the adaptive pressure and oxygen concentration control method realizes the adjustment of the oxygen concentration and the maintenance of the pressure of the air-oxygen mixing chamber 140.

Referring to fig. 4, in an embodiment, the step S10 includes:

and S110, modeling the breathing process to obtain a breathing model. In step S110, a simplified linear model is first established for a respiratory process, and discretization may be performed according to a digital sampling process by rewriting the linear model into a continuous transfer function form, so as to obtain the respiratory model. The establishment of the breathing model can simplify the calculation process, thereby estimating the linear gas path damping coefficientAnd saidLinearized dynamic coefficient of aerationA computational model is provided.

And S120, presetting and measuring intermediate parameter values. In the step S120, the relevant intermediate parameter value is a preset air-oxygen mixture expected pressure value P_dTwo actual air-oxygen mixed pressure values P before and after_aw(k)、P_aw(k-1) and flow values F (k), F (k-1) measured twice before and after. The actual air-oxygen mixed pressure value P_aw(k)、P_aw(k-1) and the flow values F (k), F (k-1) can be directly obtained from the air-oxygen mixing chamber 140. The intermediate parameter measurement process is simple to operate, namely, the intermediate parameter measurement process can be directly read from the air-oxygen mixing cavity 140, so that the self-adaptive pressure and oxygen concentration control method is further simplified.

S130, calculating the linear gas path damping coefficient according to the breathing model and the intermediate parameter value

And the linearized dynamic coefficient of downdraftIn the step S130, an iterative least square method is combined to perform recursion according to the breathing model and the intermediate parameter value, so as to complete the linearized airway damping coefficientAnd the linearized dynamic coefficient of downdraft

And (4) calculating. Due to the linearized gas path damping coefficientAnd the linearized dynamic coefficient of downdraftPartial characteristics of real parameters of the system can be reflected, so that auxiliary information of control signal design can be acted.

Referring to fig. 5, in an embodiment, the step S110 includes:

and S111, modeling the respiratory process to obtain a respiratory process linear model. In the step S111, in the process of modeling the respiratory process, the respiratory process linear model may be obtained by using the simplified linear model. The respiratory process linear model may be described as follows:

wherein, P_aw(t) is the air pressure (unit: cmH) of the air-oxygen mixing chamber 140₂O)。V_e(t) is the volume of the air and oxygen mixing chamber 140 in mL during expiration. F_e(t) is the air flow rate (unit: mL · s) of the air-oxygen mixing chamber 140 during inhalation^-1)。C_rsIs a linearized dynamic coefficient of compliance (unit: cmH)₂O·mL^-1)。R_rsIs the linear gas path damping coefficient (unit: cmH)₂O·s·mL^-1)。V_e(t) is the integral of the flow, V_eIs time.

And S112, rewriting the linear model of the respiratory process into a continuous transfer function. In step S112, an online identification of the respiratory process kinetic parameters is performed. Rewrite equation (1) to the form of a continuous transfer function, i.e.:

where s is an imaginary number representing the transfer function.

And S113, carrying out discretization treatment on the continuous transfer function to obtain the breathing model. In step S113, since the actual system is a digital process including a sampling process, the sampling period is T. Then discretizing the transfer function, considering the zeroth order keeper, yields:

wherein, P_Δ(k)＝P_aw(k)-P_aw(k-1) is the pressure difference measured in two times, wherein (k) is the value of the signal measured at the moment,in order to be able to estimate the parameters,^T(k)＝[F(k)F(k-1)]two preceding and following flow measurements.

In one embodiment, the step S120 includes:

s121, presetting an air-oxygen mixing expected pressure value P_dMeasuring the actual air-oxygen mixed pressure value P_awAnd calculating the pressure error e_p＝P_aw-P_d. In the step S121, when the preset air-oxygen mixture expected pressure value is P_dAccording to the actual air-oxygen mixed pressure value P_awThe actual air-oxygen mixed pressure value P can be calculated_awCompared with the preset air-oxygen mixed expected pressure value P_dGenerated pressure error value e_pThe pressure error value is e_p(t)＝P_aw(t)-P_d(t) of (d). Said pressure error e_p(t)＝P_aw(t)-P_d(t) may be used for subsequent calculations.

S122, continuously measuring the air-oxygen mixed pressure value P twice_aw(k)、P_aw(k-1) and air-oxygen mixture flow values F (k), F (k-1). In the step S122, the air-oxygen mixed pressure value P_aw(k)、P_aw(k-1) and the air-oxygen mixture flow values F (k), F (k-1) may be read directly from the air-oxygen mixer 140.

S123, respectively calculating the air-oxygen mixed pressure difference value P_Δ(k)＝P_aw(k)-P_aw(k-1) and the air-oxygen mixed flow value twice in succession^T(k)＝[F(k)F(k-1)]。

In one embodiment, the step S130 includes:

s131, according to the pressureForce difference P_Δ(k) And continuously carrying out twice on the air-oxygen mixed flow value (k), and carrying out parameter recursion by combining an iterative least square method, thereby estimating and obtaining a parameter value theta to be estimated^T(k) In that respect In step S131, using the least square method, the following parameter recursive estimation method can be obtained:

wherein the content of the first and second substances,represents an estimate of Θ (k). Thus, using an iterative least squares method, estimates

The value of (c). The above-mentionedCan be used to calculate the linearized gas path damping coefficient

And the linearized dynamic coefficient of downdraft

S132, according to the parameter value theta to be estimated^T(k) Calculating the linear gas path damping coefficient

And linearized dynamic coefficient of aeration

In the step S132, it is estimatedAfter the value of (c), calculating the linearization circuit damping coefficientAnd the linearized dynamic coefficient of downdraft

The calculated linear air path damping coefficient

And the linearized dynamic coefficient of downdraft

And not the actual parameters of the system. Thus, the linearized gas path damping coefficient

And the linearized dynamic coefficient of downdraftAnd cannot be directly used for control signal design. But due to the linearized gas circuit damping coefficient

And the linearized dynamic coefficient of downdraftPartial characteristics of real parameters of the system can be reflected, so that auxiliary information of control signal design can be acted. The linear gas path damping coefficient can be obtained through statisticsAnd the linearized dynamic coefficient of downdraft

Lower limit of estimated valueAnd

upper limit of

And

the linear gas path damping coefficient

And the linearized dynamic coefficient of downdraft

Can be used to perform the adaptive parametersEstimating, assisting in performing said air-oxygen mixture flow control signal u_eThe air flow control signal u_eaAnd said oxygen flow control signal u_eoThe design of (3).

In one embodiment, the step S20 includes:

s210, according to the linear gas path damping coefficient

And the linearized dynamic coefficient of downdraft

Respectively obtaining the upper limit value of the linear gas circuit damping coefficient and the linear dynamic gas guiding coefficient

And lower limit value

S220, according to the linearized gas path damping coefficient and the upper limit value of the linearized dynamic favorable gas coefficientAnd lower limit valueEstimating adaptive parameters

In the step S210 and the step S220, it should be noted that the actual parameters of the system are varied within a certain range, and the varying range is related to the coordination of the ventilator and the patient, that is, the parameter adaptive process has a very close relationship to the application effect of the ventilator. Therefore, using the parameter identification result in the parameter estimation process, the following projection parameter adaptation process can be obtained:

wherein Λ ═ diag { α ═ d₁,α₂,α₃Is the diagonal matrix of the design, and α₁，α₂And alpha₃A learning constant greater than zero. The diagonal matrix and the learning constant are designed according to actual conditions. Proj [. to]Is a projection operator for limiting the scope of parameter estimation. The parameter estimation range can be obtained according to the parameter estimation value, specifically as follows:

whereinFor the purpose of statistical flow rate variation relationships,

andstatistical upper and lower limits, respectively.

In one embodiment, the step S30 includes: s310, according to the pressure error e_pDesign feedback gain k₀e_P. S320, according to the feedback gain k₀e_PAnd the adaptive estimation parameter

Calculating the air-oxygen mixed flow control signal u_eTo achieve pressure adaptive control.

In step S310 and step S320, considering uncertainty of flow control, a certain difference exists between the flow control signal and the actual flow rate, that is, the actual flow rate is:

F_e＝u_e+d_e(7)

wherein u is_eIs the designed air-oxygen flow rate, d_eIs the flow error. It should be noted that the current command cannot be reflected on the flow rate, and therefore, the current flow rate error needs to be estimated by using the flow rate error at the previous time, that is:

d_e＝γd_m(8)

wherein d is_mIs the flow error measured at the previous time, gamma, and is a parameter reflecting the variation of the flow error.

Considering equations (1) - (3) together, one can obtain e_p＝V_e/C_rs+R_rsu_e+R_rsγd_m-P_d. Rewriting into vector form, we can obtain:

wherein, b ═ R_rsIn order for the control gain to be unknown,to measure the signal vector, θ^T＝[θ₁θ₂θ₃]＝[1/C_rsR_rsγ 1/R_rs]Is an unknown vector. The position vector needs to be estimated by a parameter adaptive method and used in the design of the control signal.

With the adaptive control method, the flow control signal can be designed as follows:

wherein k is₀e_PIs a feedback gain, where k₀Is a selected design parameter. The design parameters are determined according to actual conditions. e.g. of the type_PFor the difference between the desired pressure and the actual pressure,

for adaptive parameter estimation, the method for obtaining the parameter is shown in formula (6).

In one embodiment, the step S40 includes: s410, calculating the expected air proportion S according to the preset oxygen concentration S_aAnd the desired oxygen ratio S_o. S420, according to the expected air proportion S_aAnd the desired oxygen ratio S_oCalculating the air flow control signal u_eaAnd said oxygen flow control signal u_eoTo achieve adaptive control of oxygen concentration.

Referring to fig. 6, in an embodiment, the step S410 includes: s411, calculating the expected air proportion S according to the preset oxygen concentration S and the fixed ratio of air to oxygen_aAnd the desired oxygen ratio S_o. In one embodiment, the step S420 includes: s421 according to the desired air ratio S_aAnd the desired oxygen ratio S_oAnd the feedback gain k₀e_PAnd the adaptive estimation parameter

Calculating the oxygen flow control signal u_eaAnd said air flow control signal u_eoTo achieve adaptive control of oxygen concentration.

In the step S411 and the step S421, the oxygen concentration S is preset. The oxygen flow control signal u is generated by different oxygen and air pipelines_eoAnd said air flow control signal u_eaSatisfy u_eo+u_ea＝u_eAnd isThus, the air flow control signal can be found as:

similarly, the control signals of the oxygen flow are as follows:

wherein the content of the first and second substances,

and

the self-adaptive pressure and oxygen concentration control method comprehensively considers errors of the expected pressure and the expected oxygen concentration, and solves the problem that the related control method can only control the pressure or the oxygen concentration independently. In addition, the self-adaptive pressure and oxygen concentration control method simultaneously solves the problem that the oxygen concentration precision is greatly influenced by the difference of two paths of other flow caused by the change of system parameters. The self-adaptive pressure and oxygen concentration control method has the advantages of being simple in method, easy to achieve, low in power consumption, stable in air-oxygen mixed gas pressure, stable in oxygen concentration, high in precision and the like, and improves clinical performance of the breathing machine.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.