A pneumatic servo control device and method for a ventilator

Abstract

The present application relates to the technical field of medical equipment, and discloses a pneumatic servo control device and method for a ventilator, the device comprising a circuit board, a sensor assembly, and a control unit, wherein the control unit and the sensor assembly are integrated on the circuit board, the sensor assembly is signal-connected to the control unit, the sensor assembly comprises a differential pressure sensor and a pressure sensor, and the control unit performs dual closed-loop control based on parallel auto-disturbance rejection control based on signals collected by the differential pressure sensor and the pressure sensor, so as to achieve mixed control of air and oxygen while accurately controlling pressure and flow; wherein the inner loop adopts a parallel auto-disturbance rejection method to ensure good linearity of air and oxygen flow control, precise control, and strong robustness; the outer loop adopts PID control to achieve the integration of air-oxygen mixing control and pressure control, and reduce the use of control elements.

Description

Technical Field

[0001] The present application relates to the technical field of medical equipment, and in particular to a pneumatic servo control device and method for a ventilator. Background Art

[0002] A ventilator is an important medical device used to assist patients in breathing, maintain their oxygenation function, and buy time for the treatment of the primary disease. It plays an irreplaceable role in the treatment of critically ill patients.

[0003] Currently, existing ventilators have the following shortcomings: 1) The components that realize air and oxygen control in the ventilator are separated from the components that realize pressure and flow control, resulting in large equipment size, redundant components, high cost, and failure to meet the requirements of small, lightweight, modular and low-cost medical equipment; 2) The development of the air-oxygen mixing function and the pressure and flow control function in the ventilator is complex, the cycle is long, and the debugging is tedious, which seriously affects the equipment development progress of medical equipment manufacturers. Summary of the Invention

[0004] The purpose of this application is to provide a pneumatic servo control device and method for a ventilator, which is based on a dual closed-loop control of parallel active disturbance rejection control to achieve mixed control of air and oxygen while accurately controlling pressure and flow.

[0005] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0006] In a first aspect, a pneumatic servo control device for a ventilator is provided, the device comprising a circuit board, a sensor assembly, and a control unit, the control unit and the sensor assembly being integrated on the circuit board, the sensor assembly being signal-connected to the control unit, and the sensor assembly comprising a differential pressure sensor and a pressure sensor;

[0007] The control unit includes a parallel active disturbance rejection controller, which includes two extended state observers and a nonlinear state error feedback controller;

[0008] The extended state observer is used to expand the total disturbance into a new state variable of the system, and reconstruct all states including the original state variables and disturbances of the system using the system input and output. Its discrete form is:

[0009]

[0010] Where h is the sampling period of the differential pressure sensor and the pressure sensor, y is the real-time pressure and flow value measured by the sensor assembly, u is the output of the extended state observer, z1, z2, and z3 are the disturbance variables of the extended state observer; β 01 , β 02 , β 03is the gain of the extended state observer, d is the coefficient of the nonlinear function, which is related to the sampling period, b is the compensation factor, and fal is a nonlinear function;

[0011] The real-time pressure and flow values ​​measured by the sensor are subtracted from the z1 of the extended state observer at the previous moment to obtain d1, and the output of the extended state observer at the current moment is further calculated so that the state variables of the extended state observer track y of the controlled object, the differential of y, and the disturbance it receives;

[0012] The nonlinear state error feedback controller is used to eliminate the error and includes the following nonlinear combination:

[0013]

[0014] Where β1 and β2 are controller gains, d is the coefficient of the nonlinear function, u0 is the output of the nonlinear state error feedback control rate, e1 and e2 are the state errors of the system, and x1 is the tracking signal of the expected value. The control variable u can be obtained by eliminating the disturbance variable z3, which is expressed as:

[0015]

[0016] Where b0 is the gain of the entire system.

[0017] Preferably, in the above-mentioned ventilator pneumatic servo control device, the control unit further includes a pressure outer loop controller, and the pressure outer loop controller is used to implement pressure control based on flow proportional control through the following formula:

[0018]

[0019] Where Q is the flow signal, k p is the proportional gain, e(t) is the state error, k i is the integral adjustment coefficient, d(t) is the micro variable with time t as the variable, k d is the differential adjustment coefficient, and t is the time.

[0020] Preferably, in the above-mentioned ventilator pneumatic servo control device, the device also includes a valve body structure, a pilot chamber and a three-way valve; the valve body structure is provided with a first air inlet and a second air inlet, the first air inlet and the second air inlet are used to introduce oxygen and air respectively, the valve body structure is connected to the pilot chamber to mix the oxygen and air introduced through the first air inlet and the second air inlet in the pilot chamber, the pilot chamber has a mixed gas outlet, the upper end of the valve body structure is provided with a three-way valve, the three-way valve is electrically installed on the circuit board to be electrically connected to the control unit, the three-way valve has three ports, two of which are connected to the mixed gas outlet and the exhaust device air inlet through pipes, and the other port is provided with a quick-detachable exhalation structure.

[0021] Preferably, in the above-mentioned ventilator pneumatic servo control device, a first solenoid valve and a second solenoid valve are also integrated on the circuit board, wherein the first solenoid valve and the second solenoid valve are installed at the upper end of the valve body structure, for respectively controlling the air intake volume of the first air inlet and the second air inlet.

[0022] Preferably, in the above-mentioned pneumatic servo control device for a ventilator, the pressure sensor is used to collect the gas pressure in the pilot chamber.

[0023] Preferably, in the above-mentioned ventilator pneumatic servo control device, the differential pressure sensors are set to three, namely a first differential pressure sensor, a second differential pressure sensor and a third differential pressure sensor; wherein the first differential pressure sensor and the second differential pressure sensor are used to collect the flow signals of the first air inlet and the second air inlet, and the third differential pressure sensor is used to collect the flow signal of the quick-detachable exhalation structure.

[0024] Preferably, in the above-mentioned ventilator pneumatic servo control device, a throttle plate is arranged at the center position of the differential pressure sensor.

[0025] Preferably, in the above-mentioned ventilator pneumatic servo control device, a sliding average filter is also integrated on the circuit board, and the sliding average filter is arranged at the signal output end of the differential pressure sensor to filter the signal collected by the differential pressure sensor.

[0026] In a second aspect, a pneumatic servo control method for a ventilator is provided, the method comprising:

[0027] Flow control is implemented based on two extended state observers and a nonlinear state error feedback controller. The extended state observer is used to expand the total disturbance into a new state variable of the system and reconstruct all states including the original state variables and disturbances using the system input and output. Its discrete form is:

[0028]

[0029] Where h is the sampling period of the differential pressure sensor and the pressure sensor, y is the real-time pressure and flow value measured by the sensor assembly, u is the output of the extended state observer, z1, z2, and z3 are the disturbance variables of the extended state observer; β 01 , β 02 , β 03 is the gain of the extended state observer, d is the coefficient of the nonlinear function, which is related to the sampling period, b is the compensation factor, and fal is a nonlinear function;

[0030] The real-time pressure and flow values ​​measured by the sensor are subtracted from the z1 of the extended state observer at the previous moment to obtain d1, and the output of the extended state observer at the current moment is further calculated so that the state variables of the extended state observer track y of the controlled object, the differential of y, and the disturbance it receives;

[0031] The nonlinear state error feedback controller is used to eliminate the error and includes the following nonlinear combination:

[0032]

[0033] Where β1 and β2 are controller gains, d is the coefficient of the nonlinear function, u0 is the output of the nonlinear state error feedback control rate, e1 and e2 are the state errors of the system, and x1 is the tracking signal of the expected value. The control variable u can be obtained by eliminating the disturbance variable z3, which is expressed as:

[0034]

[0035] Where b0 is the gain of the entire system.

[0036] Preferably, the method further comprises:

[0037] Pressure control based on flow proportional control is achieved through the following formula:

[0038]

[0039] Where Q is the flow signal, k p is the proportional gain, e(t) is the state error, k i is the integral adjustment coefficient, d(t) is the micro variable with time t as the variable, k d is the differential adjustment coefficient, and t is the time.

[0040] The beneficial effects of this application are:

[0041] This application is based on dual closed-loop control of parallel active disturbance rejection control, which realizes the mixing control of air and oxygen while accurately controlling pressure and flow. The inner loop adopts the parallel active disturbance rejection method to ensure good linearity, precise control and strong robustness of air and oxygen flow control. The outer loop adopts PID control to realize the integration of air-oxygen mixing control and pressure control, reducing the use of control elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic structural diagram of a pneumatic servo control device for a ventilator according to an embodiment of the present application is shown.

[0043] Figure 2 A three-dimensional representation of a pneumatic servo control device for a ventilator according to an embodiment of the present application is shown.

[0044] Figure 3 A side view of a pneumatic servo control device for a ventilator according to an embodiment of the present application is shown.

[0045] Figure 4 The three-dimensional diagram of the quick-detachable exhalation structure according to the embodiment of the present application is shown; (a) and (b) respectively show the three-dimensional structure of the quick-detachable exhalation structure at different viewing angles.

[0046] Figure 5 Schematic diagrams of a valve body structure in a pneumatic servo control device for a ventilator according to an embodiment of the present application are shown, wherein (a) is a front schematic diagram and (b) is a back schematic diagram.

[0047] Figure 6 A schematic diagram of a pressure measurement structure according to an embodiment of the present application is shown.

[0048] Figure 7 A schematic diagram of a dual closed-loop control system based on parallel active disturbance rejection control according to an embodiment of the present application is shown.

[0049] Reference numerals:

[0050] 100. Circuit board; 200. Sensor assembly; 210. Differential pressure sensor; 220. Pressure sensor; 300. Control unit; 310. Parallel anti-disturbance control controller; 311. Extended state observer; 312. Nonlinear state error feedback controller; 320. Pressure outer loop controller; 400. Valve body structure; 410. First air inlet; 420. Second air inlet; 500. Pilot chamber; 600. Three-way valve; 700. Exhaust device; 710. Exhaust device air inlet; 800. Quick-detachable exhalation structure; 900. First solenoid valve; 1000. Second solenoid valve. DETAILED DESCRIPTION

[0051] The following describes the embodiments of the present application through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0052] The specific implementation of the present application is further described in detail below with reference to the accompanying drawings and examples.

[0053] Figure 1 The present invention provides a pneumatic servo control device for a ventilator according to an embodiment of the present invention. Figure 1 As shown, the device includes a circuit board 100, a sensor assembly 200 and a control unit 300. The control unit 300 and the sensor assembly 200 are integrated on the circuit board. The sensor assembly 200 is signal-connected to the control unit 300. The sensor assembly 200 includes a differential pressure sensor 210 and a pressure sensor 220.

[0054] In this embodiment, control unit 300 implements dual closed-loop control based on parallel active disturbance rejection control, achieving precise pressure and flow control while also controlling the mixing of air and oxygen. Specifically, control unit 300 includes a parallel active disturbance rejection controller 310, which includes two extended state observers 311 and a nonlinear state error feedback controller 312.

[0055] In the dual closed-loop control based on parallel active disturbance rejection control, flow control is used as the inner loop. The extended state observer 311 expands the total disturbance into a new state variable of the system, and then uses the system input and output to reconstruct all states including the original state variables of the system and the disturbance. Its discrete form is:

[0056]

[0057] Where h is the sampling period of the differential pressure sensor and the pressure sensor, y is the real-time pressure and flow value measured by the sensor assembly, u is the output of the extended state observer, z1, z2, and z3 are the disturbance variables of the extended state observer; β 01 , β 02 , β 03 is the gain of the extended state observer, d is the coefficient of the nonlinear function, which is related to the sampling period, b is the compensation factor, and fal is a nonlinear function.

[0058] The real-time pressure and flow value y measured by the sensor is subtracted from the z1 of the expanded state observer at the previous moment to obtain d1, and the output of the expanded state observer at the current moment is further calculated to make the state variable z of the expanded observer i (t) Track the y of the controlled object, the differential of y, and the disturbance it receives.

[0059] The nonlinear state error feedback controller 312 is based on the nonlinear state error feedback control rate to eliminate the error. The recommended nonlinear combination has the following form:

[0060]

[0061] β1 and β2 are controller gains, d is the coefficient of the nonlinear function, u0 is the output of the nonlinear state error feedback control rate, e1 and e2 are the state errors of the system, and x1 is the tracking signal of the expected value. The control variable u can be obtained by eliminating the disturbance variable z3, which is expressed as:

[0062]

[0063] Where b0 is the gain of the entire system.

[0064] The output u is proportional to the pressure and flow, achieving precise control of the flow.

[0065] To achieve pressure control based on flow proportional control, the control unit 300 includes a pressure outer loop controller 320. In the pressure outer loop controller 320, the outer loop controller and the proportional distribution structure are considered to be a flow distributor, and the output of the flow distributor serves as the input of the flow inner loop controller. The outer loop controller adopts PID control, and its principle is as follows:

[0066]

[0067] Where Q is the flow signal, k p is the proportional gain, e(t) is the state error, k i is the integral adjustment coefficient, d(t) is the micro variable with time t as the variable, k d is the differential adjustment coefficient, and t is the time.

[0068] In some embodiments, Figure 2 and Figure 3 The three-dimensional and side views of a pneumatic servo control device for a ventilator according to an embodiment of the present application are as follows: Figure 2 and Figure 3As shown, the pneumatic servo control device of the ventilator also includes a valve body structure 400, a pilot chamber 500 and a three-way valve 600; the valve body structure 400 is provided with a first air inlet 410 and a second air inlet 420, the first air inlet 410 and the second air inlet 420 are used to introduce oxygen and air respectively, the valve body structure 400 is communicated with the pilot chamber 500 to mix the oxygen and air introduced through the first air inlet 410 and the second air inlet 420 in the pilot chamber 500, the pilot chamber 500 has a mixed gas outlet 510, and the upper end of the valve body structure 400 is provided with a three-way valve 600, the three-way valve 600 is electrically mounted on the circuit board 100 to be electrically connected to the control unit 300, the three-way valve 600 has three ports, two of which are connected to the mixed gas outlet 510 and the exhaust device air inlet 710 through pipes, and the other port is provided with a quick-detachable exhalation structure 800.

[0069] In this embodiment, the exhaust device air inlet 710 is provided on the exhaust device 700, wherein the exhaust device 700 can be provided on one side of the pilot chamber 500. The first air inlet 410 and the second air inlet 420 can be connected to the oxygen supply device and the air supply device through a pipeline. The structure of the quick-detachable exhalation structure 800 is as shown in FIG. Figure 4 As shown, it can be assembled on one port of the three-way valve 600 in the form of a flange, and then can be connected to the breathing pipe in a threaded manner to connect to the corresponding air supply device, such as an air supply mask, etc. through the breathing pipe.

[0070] like Figure 4 As shown, a quick-detachable exhalation mechanism 800 is designed based on a pilot chamber structure. The exhalation flow rate is detected within the pipeline of the quick-detachable exhalation mechanism 800 using the principle of a balanced flowmeter. By controlling the pressure in the pilot chamber, the patient's exhalation airway is controlled, as well as the positive end-expiratory pressure (PEEP). This quick-detachable mechanism addresses the issue of pathogens carried by the patient's exhaled air and facilitates disinfection and cleaning by medical personnel.

[0071] like Figure 2 As shown, the circuit board 100 also integrates a first solenoid valve 900 and a second solenoid valve 1000, wherein the first solenoid valve 900 and the second solenoid valve are installed at the upper end of the valve body structure, and are used to control the air intake of the first air inlet 410 and the second air inlet 420 respectively.

[0072] The following embodiment of the present application will specifically introduce the installation positions of the various sensors included in the sensor assembly 200. The pressure sensor 220 is used to collect the gas pressure in the pilot chamber 500, and the differential pressure sensor 210 is set to three, namely, a first differential pressure sensor, a second differential pressure sensor and a third differential pressure sensor; among which, the first differential pressure sensor and the second differential pressure sensor are used to collect the flow signals of the first air inlet 410 and the second air inlet 420, and the third differential pressure sensor is used to collect the flow signal of the quick-detachable exhalation structure 800. Figure 2 and Figure 3 In FIG. 1 , A, B, C, and D are the installation positions of the pressure sensor 220, the first differential pressure sensor, the second differential pressure sensor, and the third differential pressure sensor, respectively.

[0073] It should be noted that the method of integrating electronic components on the circuit board 100 mentioned herein refers to assembling the driving circuits of each electronic component on the circuit board 100 so that the electronic components establish signal connections to achieve signal transmission and processing. The electronic components include the control unit 300, the sensor assembly 200, the three-way valve 600, the first solenoid valve 900, and the second solenoid valve 1000.

[0074] Figure 5 This is a schematic diagram of a valve body structure in a pneumatic servo control device for a ventilator according to an embodiment of the present application. Figure 5 In the figure, (a) is a front view, and (b) is a back view. The back of the valve body structure 400 is connected to a metal quick-connect connector using threads. The front is connected to the measuring structure (including but not limited to the first and second differential pressure sensors) and secured with bolts, with a sealing ring in the middle. Two proportional valves (a first solenoid valve 900 and a second solenoid valve 1000) and a three-way valve 600 can be installed on the top of the valve body 400. The two proportional valves are used to control the gas flow in the oxygen and air gas circuits, respectively. The two-position three-way valve is used to control the positive end-expiratory pressure in the pilot chamber.

[0075] Figure 6 The following is a schematic diagram of a pressure and pressure measurement structure according to an embodiment of the present application. This pressure and pressure measurement structure includes a circuit board 100, a sensor assembly 200, and a control unit 300 integrated therewith. The sensor assembly and circuit board 100 are mounted at the top of the pipeline, and a throttle plate is positioned at the center of the differential pressure sensor. To reduce the impact of turbulence on flow measurement, circular holes are designed around the center circle to regularize the flow field. The final design of the flow and pressure measurement structure is shown in the figure below.

[0076] In some embodiments, the circuit board 100 also integrates a sliding average filter, which is located at the signal output terminal of the differential pressure sensor 210 and is used to filter the signal collected by the differential pressure sensor 210. Specifically, the sliding average filter accumulates n consecutive signals and then divides them by n to obtain the average value, thereby forming a window. Whenever a new sample enters, the first sample is deleted, the new sample is added to the accumulator, and the average value is re-output. This continuous sliding window continuously calculates the signal average.

[0077] In some embodiments, flow control can be achieved through a differential pressure sensor, so data calibration and fitting are performed on the differential pressure flow measurement circuit. An air compressor is used as the air source, and a pressure reducing valve reduces the inlet pressure to 0.2 MPa. By adjusting the solenoid valve control voltage to adjust the valve opening, different differential pressures and corresponding flow measurements can be achieved.

[0078] In one embodiment, based on Figure 2 and Figure 3 In the device structure shown, MCU is selected as the control unit 300. The installation method of the device can be: the oxygen supply device is directly connected to the first air inlet 410 of the device through a pipeline, the air supply device is directly connected to the second air inlet 420 of the device through a pipeline, and the mixed gas outlet 510 is connected to a three-way connector with one end connected to the patient and the other end connected to the exhaust device inlet 710 of the device.

[0079] The working process of the device is as follows:

[0080] When the ventilator needs to output gas at a set pressure or flow rate, the staff sets the ventilation and ventilation mode, and turns on the air compressor and oxygen gas source as the gas source. After the pressure is stabilized by the pressure regulating valve, the gas flows into the control device.

[0081] The first differential pressure sensor and the second differential pressure sensor in the device monitor the flow in the air and oxygen gas circuits in real time, and the pressure sensor monitors the gas pressure in the mixing chamber in real time and feeds back the collected signal to the MCU. The MCU adjusts the control voltage in real time through an algorithm based on the feedback pressure and flow signals. Specifically, the pressure sensor, the first differential pressure sensor, and the second differential pressure sensor are used to collect the pressure and flow values ​​of the airflow inside the detection device, and the collected signals are transmitted to the MCU. During the patient's inhalation phase, the MCU outputs a control voltage through a dual closed-loop control algorithm based on parallel anti-disturbance control to change the opening of the first solenoid valve and the second solenoid valve, while achieving the proportional mixing of air and oxygen and precise control of pressure and flow. The pressure sensor collects the pressure in the pilot chamber. During the patient's exhalation phase, the three-way valve controls the pressure in the pilot chamber to achieve positive end-expiratory pressure control. The third differential pressure sensor collects the airflow flow in the quick-detachable exhalation structure.

[0082] Affected by the control voltage, the device outputs the set pressure and flow of gas, using MCU based on Figure 7 The control flow shown implements high-precision control based on the auto-disturbance rejection algorithm.

[0083] In summary, the present application can realize air-oxygen mixing, pressure-controlled ventilation, volume-controlled ventilation and other functions, and can be directly used as a core component of a ventilator developed by a manufacturer. The existing ventilator realizes air-oxygen mixing through two solenoid valves and realizes flow and pressure control through a blower, with a total of three control elements, and there is device redundancy. The present device realizes air-oxygen mixing, flow and pressure control simultaneously through two solenoid valves, which reduces costs and reduces size. Self-anti-disturbance control effectively enhances robustness and realizes linear correspondence between control voltage and output pressure and flow. At the same time, for different respiratory mechanics parameters, parameter adaptation based on recursive least squares is adopted to broaden the scope of application of the device.

[0084] The above implementation modes are only used to illustrate the present application and are not intended to limit the present application. Ordinary technicians in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present application. Therefore, all equivalent technical solutions also fall within the scope of the present application, and the scope of patent protection of the present application shall be defined by the claims.

Claims

1. A pneumatic servo control device for a ventilator, characterized in that: The device includes a circuit board, a sensor assembly and a control unit, wherein the control unit and the sensor assembly are integrated on the circuit board, the sensor assembly is connected to the control unit by signal, and the sensor assembly includes a differential pressure sensor and a pressure sensor; The control unit includes a parallel active disturbance rejection controller, which includes two extended state observers and a nonlinear state error feedback controller; The extended state observer is used to expand the total disturbance into a new state variable of the system, and reconstruct all states including the original state variables and disturbances of the system using the system input and output. Its discrete form is: Where h is the sampling period of the differential pressure sensor and the pressure sensor, y is the real-time pressure and flow value measured by the sensor assembly, u is the output of the extended state observer, z1, z2, and z3 are the disturbance variables of the extended state observer; β 01 , β 02 , β 03 is the gain of the extended state observer; d is the coefficient of the nonlinear function, which is related to the sampling period, b is the compensation factor, and fal is a nonlinear function; The real-time pressure and flow values ​​measured by the sensor are subtracted from the z1 of the previous moment of the extended state observer to obtain d1, and the output of the extended state observer at the current moment is further calculated so that the state variables of the extended state observer track y of the controlled object, the differential of y and the disturbance it receives; The nonlinear state error feedback controller is used to eliminate the error and includes the following nonlinear combination: Where β1 and β2 are controller gains, d is the coefficient of the nonlinear function, u0 is the output of the nonlinear state error feedback control rate, e1 and e2 are the state errors of the system, and x1 is the tracking signal of the expected value. The control variable u can be obtained by eliminating the disturbance variable z3, which is expressed as: Where b0 is the gain of the entire system.

2. The pneumatic servo control device for a ventilator according to claim 1, wherein: The control unit further includes a pressure outer loop controller, which is used to implement pressure control based on flow proportional control using the following formula: Where Q is the flow signal, k p is the proportional gain, e(t) is the state error, k i is the integral adjustment coefficient, d(t) is the micro variable with time t as the variable, k d is the differential adjustment coefficient, and t is the time.

3. The pneumatic servo control device for a ventilator according to claim 1, wherein: The device also includes a valve body structure, a pilot chamber and a three-way valve; the valve body structure is provided with a first air inlet and a second air inlet, the first air inlet and the second air inlet are used to introduce oxygen and air respectively, the valve body structure is communicated with the pilot chamber to mix the oxygen and air introduced through the first air inlet and the second air inlet in the pilot chamber, the pilot chamber has a mixed gas outlet, the upper end of the valve body structure is provided with a three-way valve, the three-way valve is electrically installed on the circuit board to be electrically connected to the control unit, the three-way valve has three ports, two of which are connected to the mixed gas outlet and the exhaust device air inlet through pipes, and the other port is provided with a quick-detachable exhalation structure.

4. The pneumatic servo control device for a ventilator according to claim 3, wherein: The circuit board also integrates a first solenoid valve and a second solenoid valve, wherein the first solenoid valve and the second solenoid valve are installed at the upper end of the valve body structure, and are used to control the air intake volume of the first air inlet and the second air inlet respectively.

5. The pneumatic servo control device for a ventilator according to claim 3, wherein: The pressure sensor is used to collect the gas pressure in the pilot chamber.

6. The pneumatic servo control device for a ventilator according to claim 3, wherein: The differential pressure sensors are set as three, namely the first differential pressure sensor, the second differential pressure sensor and the third differential pressure sensor; wherein the first differential pressure sensor and the second differential pressure sensor are used to collect flow signals of the first air inlet and the second air inlet, and the third differential pressure sensor is used to collect the flow signal of the quick-detachable exhalation structure.

7. The pneumatic servo control device for a ventilator according to claim 1, wherein: A throttle plate is arranged at the center of the differential pressure sensor.

8. The pneumatic servo control device for a ventilator according to claim 1, wherein: A sliding average filter is also integrated on the circuit board. The sliding average filter is arranged at the signal output end of the differential pressure sensor and is used to filter the signal collected by the differential pressure sensor.

9. A pneumatic servo control method for a ventilator, characterized in that: The method comprises: Flow control is implemented based on two extended state observers and a nonlinear state error feedback controller. The extended state observer is used to expand the total disturbance into a new state variable of the system and reconstruct all states including the original state variables and disturbances using the system input and output. Its discrete form is: Where h is the sampling period of the differential pressure sensor and the pressure sensor, y is the real-time pressure and flow value measured by the sensor assembly, u is the output of the extended state observer, z1, z2, and z3 are the disturbance variables of the extended state observer; β 01 , β 02 , β 03 is the gain of the extended state observer; d is the coefficient of the nonlinear function, which is related to the sampling period, b is the compensation factor, and fal is a nonlinear function; The real-time pressure and flow values ​​measured by the sensor are subtracted from the z1 of the previous moment of the extended state observer to obtain d1, and the output of the extended state observer at the current moment is further calculated so that the state variables of the extended state observer track y of the controlled object, the differential of y and the disturbance it receives; The nonlinear state error feedback controller is used to eliminate the error and includes the following nonlinear combination: Where β1 and β2 are controller gains, d is the coefficient of the nonlinear function, u0 is the output of the nonlinear state error feedback control rate, e1 and e2 are the state errors of the system, and x1 is the tracking signal of the expected value. The control variable u can be obtained by eliminating the disturbance variable z3, which is expressed as: Where b0 is the gain of the entire system.

10. The method according to claim 9, wherein The method further comprises: Pressure control based on flow proportional control is achieved through the following formula: Where Q is the flow signal, k p is the proportional gain, e(t) is the state error, k i is the integral adjustment coefficient, d(t) is the micro variable with time t as the variable, k d is the differential adjustment coefficient, and t is the time.

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