A method and system for pressure tracking control of a high pressure proportional flow valve on a ventilator independent of RC and a ventilator

Abstract

The present application belongs to the technical field of medical devices, and particularly relates to a pressure tracking control method and system for a high-pressure proportional flow valve on a respirator independent of RC, and a respirator. The method comprises the following steps: step 1) inputting pressure set as a target pressure value into both feedforward control and PID control, and obtaining a gas expected flow; and step 2) collecting an actual pressure value of output gas in real time, subtracting the output of the disturbance observer from the gas expected flow in step 1), and adjusting parameters of the feedforward control and the PID control to realize consistency between airway pressure at a user end and the target pressure value. The method can be applied to different loads, avoids dependence on load parameters in a traditional control algorithm, and improves pressure control performance of the high-pressure proportional valve.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of medical devices, and particularly relates to a high-pressure proportional flow valve pressure tracking control method and system on a respirator independent of RC, and a respirator. BACKGROUND

[0002] Using a high-pressure proportional flow valve to control the user end airway pressure is a common control method on current respirators. The front end of the proportional flow valve is connected to a high-pressure gas source, and the proportional flow valve output flow is controlled by real-time control of the opening size of the proportional flow valve, thereby indirectly realizing control of the user end airway pressure. In current respirators, proportional flow valve control pressure needs to depend on the user's respiratory mechanics parameter RC, and real-time control is combined with sensor feedback. Generally, the user's respiratory mechanics parameter RC is unknown and needs to be obtained through recursive least squares identification. However, when the user's air resistance is large or the user has spontaneous respiration, the result obtained through parameter identification often deviates greatly from the true value, resulting in oscillation or even divergence of pressure control. SUMMARY

[0003] The present application aims to overcome the defects of the prior art and proposes a high-pressure proportional flow valve pressure tracking control method on a respirator independent of RC and a respirator.

[0004] In order to achieve the above technical purpose, the present application proposes a high-pressure proportional flow valve pressure tracking control method on a respirator independent of RC, comprising:

[0005] Step 1) inputting the pressure set as a target pressure value into both feedforward control and PID control to obtain the expected gas flow;

[0006] Step 2) real-time acquisition of the actual pressure value of the output gas, subtraction of the output of the disturbance observer from the expected gas flow of step 1), and adjustment of the parameters of the feedforward control and the PID control to realize consistency of the airway pressure at the user end with the target pressure value.

[0007] Preferably, the feedforward control of step 1) uses a nominal model G m satisfying the following formula:

[0008]

[0009] wherein R is the nominal model air resistance, C is the nominal model compliance, C t is the nominal model pipeline compliance, and s is the complex frequency domain variable of Laplace transform.

[0010] Preferably, the PID control of step 1) satisfies the following formula:

[0011]

[0012] wherein k p1 is a linear proportional term coefficient, k p2 is a nonlinear proportional term coefficient, k i is an integral term coefficient, k d is a differential term coefficient, e = P ref - P aw is a pressure control error, P aw is a user-side airway pressure, P ref is a set target pressure value.

[0013] Preferably, the feedforward control parameters adjusted in step 2) include R, C and C t , the PID control parameters include k p1 , k p2 , k i and k d .

[0014] Preferably, step 2) includes:

[0015] Real-time collection of user-side airway pressure P aw , combined with current user-side inhalation flow Q, the output of the disturbance observer Subtract the gas expected flow output by step 1) to obtain the corrected expected flow Q, pass through the flow control loop In with transfer function approximation 1, deliver to the user side, to satisfy the following formula:

[0016]

[0017] wherein G p is the controlled object.

[0018] Preferably, the output of the disturbance observer satisfies the following formula:

[0019]

[0020] The disturbance observer includes a low-pass filter, and the low-pass filter F satisfies the following formula:

[0021]

[0022] wherein τ is the filter time constant.

[0023] Preferably, step 2) further includes:

[0024] Step 3) inputs the pressure set as the target pressure value into the feedforward controller and the pressure feedback at the same time, and calculates to obtain the forward path expected flow;

[0025] Step 4) Real-time acquisition of the actual pressure value of the output gas, subtraction of the expected flow value of the forward path obtained in step 3) after the interference observer, input into the exhalation valve, and obtaining of the final target flow value.

[0026] Preferably, y(n) input into the exhalation valve in step 4) is:

[0027] y(n) = y f (n) + y p (n) + y q (n)

[0028] Wherein, y f (n) is the feedforward control, y p (n) and y q (n) are the pressure feedback and the flow feedback, respectively.

[0029]

[0030] Wherein, P ref is the set target pressure, a, b, c are parameters obtained through PEEP valve calibration, The overall meaning is that the pressure P ref is the opening / closing valve point of the exhalation valve; the pressure feedback y p (n) adopts incremental PD control, and the flow feedback y q (n) adopts incremental P control.

[0031] In another aspect, the present application provides a high-pressure proportional flow valve pressure tracking control system on a breathing machine independent of RC, comprising:

[0032] A calculation module for simultaneously inputting the pressure set as the target pressure value into the feedforward control and the PID control, and obtaining the expected flow value of the gas through calculation;

[0033] An adjustment module for real-time acquisition of the actual pressure value of the output gas, subtraction of the output of the interference observer from the expected flow value of the gas obtained by the calculation module, and adjustment of the parameters of the feedforward control and the PID control to realize the consistency of the airway pressure of the user end with the target pressure value.

[0034] In another aspect, the present application provides a breathing machine comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the high-pressure proportional flow valve pressure tracking control method on a breathing machine independent of RC.

[0035] Compared with the prior art, the present application has the following advantages:

[0036] The high-pressure proportional flow valve pressure control method provided by the application can be applied to different loads, avoids the dependence on load parameters in traditional control algorithms, and improves the high-pressure proportional flow valve pressure control performance. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a method flowchart of embodiment 1 of the application;

[0038] Figure 2 is a method flowchart newly added in embodiment 2 of the application compared with embodiment 1. DETAILED DESCRIPTION

[0039] The pressure control method described in the application comprises two parts, namely a high-pressure proportional flow valve controller and an exhalation valve controller. The high-pressure proportional flow valve controller comprises three parts, namely feedforward control, PID control and disturbance observer; and the exhalation valve controller comprises feedforward control and PD control.

[0040] The technical solutions of the application will be described in detail below with reference to the drawings and embodiments.

[0041] Embodiment 1

[0042] Embodiment 1 of the application proposes a high-pressure proportional flow valve pressure tracking control method on a respirator independent of RC, namely a high-pressure proportional flow valve controller, mainly used for adult users. The method comprises the following steps.

[0043] Step 1) inputting the pressure set as a target pressure value into two paths of feedforward control and PID control at the same time to obtain a gas expected flow;

[0044] Step 2) collecting an actual pressure value of output gas in real time, subtracting the output of the disturbance observer from the gas expected flow in step 1), and adjusting the parameters of the feedforward control and the PID control to realize that the airway pressure at the user end is consistent with the target pressure value.

[0045] The high-pressure proportional flow valve control structure is shown in Figure 1 .

[0046] To improve the dynamic performance of the system, feedforward is introduced into the controller. The feedforward control is Q Model in the figure, and G m is a nominal model, satisfying

[0047]

[0048] The meanings of the parameters in formula (1) are as follows:

[0049] R is a nominal model gas resistance, C is a nominal model compliance, and C t is a nominal model pipeline compliance.

[0050] PID control is Q in the figure e term, satisfying

[0051]

[0052] The meaning of each parameter in formula (2) is as follows:

[0053] k p1 linear proportional term coefficient, k p2 nonlinear proportional term coefficient, k i integral term coefficient, k d derivative term coefficient.

[0054] To improve the anti-interference performance of the system, an interference observer is introduced in the controller, and the output of the observer is term,

[0055] the output of the interference observer satisfies the following formula:

[0056]

[0057] where F is a low-pass filter, satisfying

[0058]

[0059] where τ is the time constant of the filter.

[0060] In addition, In in the figure is a flow control loop, which is realized by a pre-measured high-pressure proportional flow valve model, G p is the controlled object. By analyzing the closed-loop system through Mason's formula, it can be obtained that, with P ref as the input and P aw as the output, the transfer function is:

[0061]

[0062] In addition, the transfer function from the disturbance d to the output P aw is

[0063]

[0064] Combining (4), (5), it can be obtained that

[0065]

[0066] From (4) to (6), if the inner loop transfer function In=1 and F=1 (i.e. within the passband range of the low-pass filter), there are

[0067]

[0068]

[0069] Equation (7) shows that in this case the airway pressure can achieve full tracking of the desired pressure, in addition to

[0070]

[0071] Equation (8) shows that the controller can achieve complete suppression of low-frequency disturbances.

[0072] Embodiment 2

[0073] Embodiment 2 of the present application proposes an RC-independent pressure tracking control method for high-pressure proportional flow valve on a ventilator, i.e., corresponding to the high-pressure proportional flow valve controller and the exhalation valve controller. Mainly used for neonatal users, the method includes:

[0074] Step 1) input the pressure set as the target pressure value into both the feedforward control and the PID control, and calculate the expected flow of the gas;

[0075] Step 2) real-time collect the actual pressure value of the output gas, subtract the output of the disturbance observer from the expected flow of the gas in step 1), and adjust the parameters of the feedforward control and the PID control to achieve consistency between the airway pressure at the user end and the target pressure value.

[0076] Step 3) input the pressure set as the target pressure value into both the feedforward controller and the pressure feedback, and calculate the expected flow of the forward path;

[0077] Step 4) real-time collect the actual pressure value of the output gas, subtract the expected flow of the forward path obtained in step 3) after passing through the disturbance observer, and input it into the exhalation valve to obtain the final target flow.

[0078] Among them, step 3) and step 4) correspond to the exhalation valve controller.

[0079] The exhalation valve control structure is as shown in Figure 2 , which is given by equation (9):

[0080] y(n) = y f (n) + y p (n) + y q (n) (9)

[0081] Where y f is the feedforward, y p and y q are the pressure feedback and flow feedback, respectively.

[0082] The feedforward control y f can be represented as:

[0083]

[0084] where P ref is the target pressure, a, b, c are parameters obtained by PEEP valve calibration, the overall meaning is the pressure P ref the opening (closing) valve point of the lower exhalation valve.

[0085] The pressure feedback control adopts the form of incremental PD control, which is given by (11):

[0086]

[0087] where

[0088] e = P ref -P aw (12)

[0089]

[0090] The flow feedback adopts the form of incremental P control, which is given by (14):

[0091] y q (n) = y q (n-1) + K flow Q exp (14)

[0092] where Q exp is the exhalation flow.

[0093] Embodiment 3

[0094] Embodiment 3 of the present application provides a high-pressure proportional flow valve pressure tracking control system on a respirator independent of RC, which is realized based on the method of embodiment 1 or embodiment 2. Corresponding to the application of embodiment 1 to adult users, the system comprises:

[0095] a calculation module for inputting the pressure set as the target pressure value into both the feedforward control and the PID control at the same time to obtain the expected flow of the gas by calculation;

[0096] an adjustment module for collecting the actual pressure value of the output gas in real time, subtracting the output of the disturbance observer from the expected flow of the gas obtained by the calculation module, and adjusting the parameters of the feedforward control and the PID control to realize the consistency of the airway pressure at the user end with the target pressure value.

[0097] Corresponding to the application of embodiment 2 to neonates, the system comprises:

[0098] a first calculation module for inputting the pressure set as the target pressure value into both the feedforward control and the PID control at the same time to obtain the expected flow of the gas by calculation;

[0099] Adjusting module, for collecting actual pressure value of output gas in real time, subtracting output of disturbance observer from expected flow of gas obtained by first calculating module, adjusting parameters of feedforward control and PID control, realizing consistency of airway pressure of user end with target pressure value.

[0100] Second calculating module, for inputting pressure set as target pressure value into feedforward controller and pressure feedback at the same time, obtaining expected flow of forward path by calculation;

[0101] Output module, for collecting actual pressure value of output gas in real time, inputting into expiration valve after subtracting expected flow of forward path obtained by second calculating module after disturbance observer, obtaining final target flow.

[0102] Embodiment 4

[0103] Embodiment 4 of the present application provides a breathing machine, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements each step in the above-mentioned embodiment 1 or embodiment 2 when executing the computer program.

[0104] Invention points:

[0105] 1) By introducing disturbance observer, the controller no longer depends on the respiratory mechanics parameters of the user;

[0106] 2) The control mode of feedforward plus PID plus disturbance observer can not only quickly control to the target pressure, but also reduce the influence of external disturbance on control;

[0107] 3) The expiration valve participates in the inspiration control, reducing the overshoot under large air resistance.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A breathing machine, characterized by, The application relates to a computer program product comprising a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor implements a pressure tracking control method for a high-pressure proportional flow valve on a respirator which is independent of RC, and the method comprises the following steps: Step 1) inputting pressure set as a target pressure value into both a feedforward control and a PID control to obtain a gas expected flow; Step 2) collecting an actual pressure value of output gas in real time, subtracting the output of a disturbance observer from the gas expected flow obtained in step 1), and adjusting parameters of the feedforward control and the PID control to realize that the airway pressure at a user end is consistent with the target pressure value; The feedforward control of step 1) employs a nominal model G m satisfies the following equation: where R is the nominal model gas resistance, C is the nominal model compliance, C t is the nominal model line compliance, and s is the Laplace-transformed complex frequency domain variable; The PID control in step 1) satisfies the following formula: where k p1 is a linear proportional term coefficient, k p2 is a nonlinear proportional term coefficient, k i is an integral term coefficient, k d is a derivative term coefficient, e = P ref - P aw is a pressure control error, P aw is a user-side airway pressure, P ref is a set target pressure value.

2. The ventilator of claim 1, wherein, The feedforward control parameters adjusted in the step 2) include R, C and C t , and the PID control parameters include k p1 , k p2 , k i and k d .

3. The ventilator of claim 1, wherein, Step 2) comprises the following: Real-time acquisition of airway pressure P of user end aw , combined with the current user end inhalation flow, the output of the disturbance observer Subtract the expected flow of gas output in step 1) to get the modified expected flow, which is approximated by the flow control loop In with a transfer function of 1, delivered to the user end, satisfying the following formula: wherein G p is the controlled object.

4. The ventilator of claim 3, wherein, the output of the disturbance observer satisfies the following equation: The disturbance observer comprises a low-pass filter, and the low-pass filter F satisfies the following formula: Wherein, tau is a filter time constant.

5. The ventilator of claim 1, wherein, Step 2) further comprises the following: Step 3) inputting pressure set as a target pressure value into a feedforward controller and a pressure feedback to obtain a forward path expected flow; Step 4) collecting an actual pressure value of output gas in real time, subtracting the forward path expected flow obtained in step 3) after passing through a disturbance observer, and inputting the gas pressure into an exhalation valve to obtain a final target flow.

6. The ventilator of claim 5, wherein, The gas pressure y(n) input into the exhalation valve in step 4) is: y(n) = y f (n) + y p (n) + y q (n) where y f (n) is the pressure feedback control, y p (n) is the flow feedback control, and y q (n) is the pressure feedback and flow feedback, respectively. where P ref is the set target pressure, a, b, c are parameters obtained from PEEP valve calibration, Overall meaning is pressure P ref Lower exhalation valve opening / closing valve point; pressure feedback y p (n) Incremental PD control is used, flow feedback y q (n) Incremental P control is used.

7. An RC independent pressure following control system for a high pressure proportional flow valve on a ventilator, comprising: Comprises: a calculation module for inputting pressure set as a target pressure value into both a feedforward control and a PID control to obtain a gas expected flow; and an adjustment module for collecting an actual pressure value of output gas in real time, subtracting the output of a disturbance observer from the gas expected flow obtained by the calculation module, and adjusting parameters of the feedforward control and the PID control to realize that the airway pressure at a user end is consistent with the target pressure value; wherein The nominal model G employed by the feedforward control in the solution module m satisfies the following equation: where R is the nominal model gas resistance, C is the nominal model compliance, C t is the nominal model line compliance, and s is the Laplace-transformed complex frequency domain variable; the PID control in the calculation module satisfies the following formula: where k p1 is a linear proportional term coefficient, k p2 is a nonlinear proportional term coefficient, k i is an integral term coefficient, k d is a derivative term coefficient, e = P ref - P aw is a pressure control error, P aw is a user end airway pressure, P ref is a set target pressure value.

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