Micro proportional valve control method based on active disturbance rejection control

Abstract

The invention discloses a miniature proportional valve control method based on active-disturbance-rejection control, and relates to the technical field of miniature proportional valve control, and the method comprises the steps that a target flow set value is received and is used as a control signal to be sent to a control unit, and the control unit comprises a tracking differentiator, an expansion state observer and a nonlinear feedback controller; the tracking differentiator processes the target flow set value to obtain a differential input signal; the expansion state observer receives the differential input signal and the actual flow feedback signal, and estimates the total disturbance of the system in real time to obtain a disturbance estimation value; the non-linear feedback controller combines the differential input signal and the disturbance estimation value to generate a compensation current signal; the compensation current signal is used as a control parameter of the micro proportional valve, and the position of the valve element is accurately adjusted. An active disturbance rejection control algorithm is adopted, the control performance and disturbance rejection are improved, accurate flow control of the micro proportional valve is achieved, and the micro proportional valve is more suitable for industrial application with high requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro proportional valve control, more particularly to a micro proportional valve control method based on active disturbance rejection control. BACKGROUND

[0002] As an important component of the automation control field, pneumatic systems encompass a variety of pneumatic valves in their constituent elements, each with specific functions, including but not limited to controlling direction, on-off, pressure, and flow rate. Among these elements, micro proportional valves are widely used in pneumatic systems. As pressure or flow control elements, their working principle is to generate electromagnetic force through current excitation, thereby pushing the valve core to move and achieving precise control of the valve. The structure mainly includes coil, moving valve core, static valve core, and other essential elements.

[0003] Currently, micro proportional valves are increasingly used in gas control systems, but traditional control algorithms are difficult to meet the needs of small flow control in some cases. These traditional algorithms have a series of problems and shortcomings, such as the complexity of parameter adjustment, the need for experience and experiments to determine appropriate parameter values, and the difficulty of adapting to different working conditions and environmental changes. For nonlinear, time-varying, and highly uncertain systems, traditional control algorithms perform poorly, easily leading to overshoot, oscillation, steady-state error, and other phenomena.

[0004] Therefore, the present application aims to improve the precision, dynamic response, and anti-interference of micro proportional valves through a new active disturbance rejection control strategy, thereby providing a more reliable and efficient solution for the application of micro proportional valves in various fields. SUMMARY

[0005] In view of the above, the present application provides a micro proportional valve control method based on active disturbance rejection control, which improves the precision, dynamic response, and anti-interference of micro proportional valves.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] A micro proportional valve control method based on active disturbance rejection control, comprising:

[0008] Receiving a target flow set value and sending it as a control signal to a control unit, which includes a tracking differentiator, an extended state observer, and a nonlinear feedback controller;

[0009] The tracking differentiator processes the target flow set value to obtain a differential input signal;

[0010] The extended state observer receives an actual flow feedback signal, estimates the total disturbance of the system in real time, and obtains a disturbance estimation value;

[0011] The nonlinear feedback controller combines the differential input signal and the disturbance estimate to generate a compensation current signal;

[0012] The compensation current signal is used as a control parameter of the micro proportional valve to accurately adjust the spool position.

[0013] Preferably, the differential input signal includes a reference flow rate and a reference flow rate change rate, and the calculation formula is:

[0014]

[0015] wherein v1 is the reference flow rate, is a tracking transition flow signal realized by a dynamic differential equation, v2 represents the reference flow rate change rate, represents a differential signal of the flow rate change rate, the fast factor r = 100 Hz, and v0 represents a target flow rate set value.

[0016] Preferably, the extended state observer receives an actual flow rate feedback signal to estimate the total disturbance of the system in real time to obtain a disturbance estimate, and specifically includes:

[0017] The extended state observer receives an actual flow rate feedback signal measured by a flow rate sensor;

[0018] The error is estimated in real time based on the actual flow rate feedback signal and the reference flow rate estimate;

[0019] The disturbance estimate is calculated based on the error.

[0020] Preferably, the error and the disturbance estimate calculation formula are:

[0021]

[0022] wherein e is an estimation error of z1 relative to x1, x1 represents the actual flow rate feedback signal, z1 represents the reference flow rate estimate, z2 represents the reference flow rate change rate estimate, and z3 represents the disturbance estimate, represents a change rate of the reference flow rate estimate, represents a differential signal of the reference flow rate change rate estimate, represents a change rate of the total disturbance estimate, β1, β2, and β3 are observer gains that need to be adjusted, and fal is a continuous nonlinear power function:

[0023]

[0024] A calculation step h is selected for discretization, and finally the discrete expression of the second-order nonlinear extended state observer is:

[0025]

[0026] Wherein, k = 1, 2, 3..., represents the length of time interval.

[0027] Preferably, the nonlinear feedback controller combines the differential input signal and the disturbance estimate to generate a compensation current signal, specifically including:

[0028] Calculate the flow error based on the reference flow and the estimate of the reference flow:

[0029] Calculate the error rate based on the reference flow rate and the estimate of the reference flow rate:

[0030] Calculate the nonlinear control signal based on the flow error and the error rate:

[0031] Compensate the estimate of the total disturbance into the nonlinear control signal to obtain the actual control quantity:

[0032] Convert the actual control quantity into a compensation current signal.

[0033] Preferably, the nonlinear control signal calculation formula is:

[0034]

[0035] Wherein, e1 represents the flow error, e2 represents the error rate, u0 represents the nonlinear control signal; δ3, δ4 are the linear interval lengths corresponding to e1(k), e2(k) respectively; α3, α4 are the nonlinear function power exponents corresponding to e1(k), e2(k) respectively, and the value range is usually between 0 and 1.

[0036] Preferably, the actual control quantity calculation formula is:

[0037]

[0038] Wherein, u represents the actual control quantity, u0 represents the nonlinear control signal, z3 represents the estimate of the total disturbance, and b0 is the control gain.

[0039] Preferably, the actual flow feedback signal is measured by a flow sensor and fed back to the extended state observer through a signal amplification unit.

[0040] According to the above technical solution, compared with the prior art, the application provides a micro proportional valve control method based on active disturbance rejection control, which adopts an active disturbance rejection control algorithm, improves the control performance and disturbance rejection, realizes accurate flow control of the micro proportional valve, and makes the micro proportional valve more suitable for high-demand industrial applications. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the accompanying drawings in the following description only aim to explain the embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative effort on the basis of the provided drawings.

[0042] Figure 1 A flow chart of a micro proportional valve control method based on active disturbance rejection control is provided.

[0043] Figure 2 A principle diagram of active disturbance rejection control is provided.

[0044] Figure 3 A block diagram of a micro proportional valve control system is provided. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the present application.

[0046] The embodiments of the present application disclose a micro proportional valve control method based on active disturbance rejection control, as shown in Figure 1 and Figure 3 , comprising:

[0047] receiving a target flow set value and sending it as a control signal to a control unit, the control unit comprising a tracking differentiator, an extended state observer and a nonlinear feedback controller;

[0048] The tracking differentiator processes the target flow set value to obtain a differential input signal;

[0049] The extended state observer receives an actual flow feedback signal and estimates the total disturbance of the system in real time to obtain a disturbance estimation value;

[0050] The nonlinear feedback controller combines the differential input signal and the disturbance estimation value to generate a compensation current signal;

[0051] The compensation current signal is used as a control parameter of the micro proportional valve to accurately adjust the position of the valve core.

[0052] The control unit of the application adopts a disturbance-rejection control algorithm, which realizes accurate control of the controlled object by real-time estimation and compensation of internal and external disturbances in the system. It regards the uncertainty and disturbance in the system as "total disturbance" and estimates and compensates it. The control unit mainly consists of a tracking differentiator (TD), an extended state observer (ESO) and a nonlinear state error feedback controller (NLSEF). Disturbance-rejection control can realize accurate flow regulation of a miniature proportional valve, especially in the case of small flow control, and it performs better. The advantage of this control method is that it can more accurately adapt to complex working environments and effectively resist external factors that interfere with the system. Disturbance-rejection control has better robustness and can maintain the stability of the system under different operating conditions.

[0053] The specific implementation process of the disturbance-rejection control algorithm of the application will be described as follows: Figure 2

[0054] (1) The tracking differentiator is designed for the input characteristics of the miniature proportional valve. The target flow set value is smoothly transitioned to obtain the differential input signal, including the transition process signal v1 (reference flow) and its derivative v2 (reference flow rate) as follows:

[0055]

[0056] Where v1 is the reference flow, is the tracking transition flow signal realized by a dynamic differential equation, v2 represents the reference flow rate, represents the differential signal of the flow rate, the fast factor r = 100 Hz, and the transition time T = 0.1 s is ensured;

[0057] (2) The extended state observer is a core component of the disturbance-rejection control. It tracks the gas flow in the system through the flow sensor, monitors the system state in real time, and also compensates for the total disturbance in the system model in feedback form to improve the robustness of the system.

[0058] The flow sensor measures the actual flow feedback signal x1 in real time and feeds it back to the extended state observer through the signal amplification unit;

[0059] The error e = z1-x1 is estimated in real time based on the actual flow feedback signal and the estimated value of the reference flow;

[0060] The extended state observer estimates the flow error e1 = v1-z1, the error rate e2 = v2-z2, and the total disturbance f(x1,x2) (which is the unknown nonlinear model in the system model and all disturbances, including valve core friction, gas viscous resistance, model error, etc.) in real time. The transfer function is rewritten as a state equation:​

[0061]

[0062] wherein V = x1 represents an actual flow feedback signal, represents a differential signal of the actual flow feedback signal, x2 represents an actual flow rate of change, represents a differential signal of the actual flow rate of change, b0 is a control gain, which is a debugging parameter, participates in debugging of a subsequent control algorithm parameter, and can improve estimation capability and universality of the algorithm, and u is an actual control amount.

[0063] The estimation values of the reference flow z1 (estimation of the flow feedback signal x1), the estimation value of the reference flow rate of change z2 (estimation of the flow rate of change x2), and the disturbance estimation value z3 (estimation of the total disturbance f(x1, x2)) are obtained by estimating each order state and disturbance through a state equation:

[0064]

[0065] wherein β1, β2, β3 are observer gains that need to be debugged, the size of the parameter β1 mainly affects the steady-state error size of the system, the size of the parameter β2 mainly affects the dynamic response performance of the system, and the size of the parameter β3 mainly affects the response performance of the system to the total disturbance estimation.

[0066] In order to prevent high-frequency chattering phenomenon near the origin when discretely calculating, a continuous nonlinear power function fal(e, α, δ) is introduced, and the expression is as follows:

[0067]

[0068] wherein α is an exponential parameter of the nonlinear function, in order to ensure that the feedback function has the characteristics of “small error, large gain”, the value range is between 0 and 1 (0.5 is taken in the embodiment), δ is a linear interval length, which is set according to the system sensitivity and noise level, the larger the parameter δ is, the larger the linear interval of the function fal(e, α, δ) is, and the smaller the nonlinear interval is, and is usually 0.01-0.1 (0.01 is taken in the embodiment). δ1, δ2 are linear interval lengths corresponding to formula (3) respectively, which are determined according to requirements; and α1, α2 are power exponents of the nonlinear function corresponding to formula (3) respectively.

[0069] The calculation step is selected to be h, formula (3) is discretized, and the discrete expression of the second-order nonlinear extended state observer is finally obtained as:

[0070]

[0071] In the formula, k = 1, 2, 3…, representing the length of the time interval, which is determined according to the calculation step h; for the convenience of writing, define fe1, fe2 as the corresponding α, δ continuous nonlinear power function respectively.

[0072] (3) The nonlinear feedback controller measures the error between the state variable and the ESO state estimation value, and outputs the controller control quantity combined with the total disturbance compensation value of the ESO. Specifically, it includes:

[0073] Calculate the flow error based on the reference flow and the estimated value of the reference flow:

[0074] Calculate the error rate based on the reference flow rate and the estimated value of the reference flow rate:

[0075] Calculate the nonlinear control signal based on the flow error and the error rate:

[0076] Compensate the estimated value of the total disturbance into the nonlinear control signal to get the actual control quantity:

[0077] Convert the actual control quantity into a compensation current signal.

[0078] The feedback control law (discrete representation) is designed as follows:

[0079]

[0080] Where e1 represents the flow error, e2 represents the error rate, u0 represents the nonlinear control signal; δ3, δ4 are the linear interval lengths corresponding to e1(k), e2(k) respectively; α3, α4 are the nonlinear function power exponents corresponding to e1(k), e2(k) respectively, which usually take values between 0 and 1.

[0081] Finally, in order to suppress the uncertainty caused by the nonlinearity of the system and the inaccuracy of the model, as well as the unknown disturbance affecting the output signal from the outside of the system, the sum of the internal and external disturbances z3 estimated by the extended state observer is compensated into the feedback control signal u0, which together determines the final actual control quantity u, that is:

[0082]

[0083] Convert the actual control quantity u into a driving current I, drive the spool to move to change the valve opening, and the actual flow x changes with the valve opening, the sensor feeds back the new value to the control unit, forming a closed-loop control.

[0084] The system disturbance inside and outside is estimated and compensated in real time by the extended state observer (ESO), which significantly improves the anti-interference ability of the system. The dynamic response is optimized by the nonlinear feedback feedback device (NLSEF) and the tracking differentiator (TD), the transition time is shortened, and the overshoot is reduced. It does not depend on the accurate system model, estimates the total disturbance by ESO, and reduces the requirement for mathematical model.

[0085] The various embodiments are described in the specification by way of progression, each building on the last to facilitate ease of understanding. The same reference numerals are used throughout the drawings and text to indicate the same or similar components. The embodiments disclosed are only examples, and the scope of the application should not be limited to these disclosed embodiments. For example, it should be apparent to those with skill in the art that the scope of the application includes embodiments in which the order of steps is different from the order of steps described in the embodiments described above. The scope of the application also includes embodiments in which the steps have different or additional elements. It is intended that each element of each claim is addressed by at least one step or element in one of the embodiments disclosed in the specification.

[0086] The above description of disclosed embodiments provides enough information to enable those with skill in the art to make and use the application. Various modifications to these embodiments will be readily apparent to those with skill in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Accordingly, the application is not to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A micro proportional valve control method based on a disturbance decoupling control, characterized by, The application relates to a control method for a micro proportional valve, which comprises the following steps: Receiving a target flow setting value and sending the target flow setting value as a control signal to a control unit, wherein the control unit comprises a tracking differentiator, an extended state observer and a nonlinear feedback controller; The tracking differentiator processes the target flow setting value to obtain a differential input signal; The extended state observer receives an actual flow feedback signal, estimates a total disturbance of the system in real time, and obtains a disturbance estimation value; The nonlinear feedback controller combines the differential input signal and the disturbance estimation value to generate a compensation current signal; The compensation current signal is used as a control parameter of the micro proportional valve to accurately adjust the position of a valve core.

2. The control method of a micro proportional valve based on active disturbance rejection control according to claim 1, wherein, The differential input signal comprises a reference flow and a reference flow rate, and the calculation formula is as follows: wherein v1 is a reference flow rate, is a tracking transition flow rate signal achieved by a dynamic differential equation, v2 represents a reference flow rate change rate, is a differential signal representing a flow rate change rate, a fast factor r = 100 Hz, and v0 represents a target flow rate set value.

3. The control method of a micro proportional valve based on active disturbance rejection control according to claim 2, wherein, The extended state observer receives an actual flow feedback signal measured by a flow sensor, estimates a total disturbance of the system in real time, and obtains a disturbance estimation value, and the specific steps comprise the following steps: The extended state observer receives an actual flow feedback signal measured by a flow sensor; An error is estimated in real time based on the actual flow feedback signal and the estimation value of the reference flow; A disturbance estimation value is calculated based on the error.

4. The control method of a micro proportional valve based on active disturbance rejection control according to claim 3, wherein, The calculation formula of the error and the disturbance estimation value is as follows: where e is an estimation error of z1 with respect to x1, x1 represents an actual flow feedback signal, z1 represents an estimated value of the reference flow, z2 represents an estimated value of the reference flow rate of change, and z3 represents a disturbance estimated value, represents a rate of change of the reference flow estimated value, represents a differential signal of the reference flow rate estimated value, represents a rate of change of the total disturbance estimated value, β1, β2, β3 are observer gains that need to be tuned, and fal is a continuous nonlinear power function: A calculation step length h is selected for discretization, and the discrete expression of the second-order nonlinear extended state observer is finally obtained as follows: In the formula, k=1, 2, 3... represents the length of a time interval.

5. A control method of a micro proportional valve based on active disturbance rejection control according to claim 4, characterized in that, The nonlinear feedback controller combines the differential input signal and the disturbance estimation value to generate a compensation current signal, and the specific steps comprise the following steps: A flow error is calculated based on the reference flow and the estimation value of the reference flow: An error rate is calculated based on the reference flow rate and the estimation value of the reference flow rate; A nonlinear control signal is calculated based on the flow error and the error rate; The estimation value of the total disturbance is compensated into the nonlinear control signal to obtain an actual control amount; The actual control amount is converted into a compensation current signal.

6. A control method of a micro proportional valve based on active disturbance rejection control according to claim 5, wherein, The calculation formula of the nonlinear control signal is as follows: In the formula, e1 represents the flow error, e2 represents the error rate, u0 represents the nonlinear control signal, delta3 and delta4 are linear interval lengths corresponding to e1(k) and e2(k) respectively, and alpha3 and alpha4 are nonlinear function power exponents corresponding to e1(k) and e2(k) respectively, and the values of the nonlinear function power exponents are usually between 0 and 1.

7. The method according to claim 5, wherein the method is characterized by, The calculation formula of the actual control amount is as follows: In the formula, u represents the actual control amount, u0 represents the nonlinear control signal, z3 represents the estimation value of the total disturbance, and b0 is a control gain.

8. The control method of a micro proportional valve based on a disturbance decoupling control according to claim 3, wherein, The actual flow feedback signal is measured by a flow sensor and fed back to the extended state observer through a signal amplification unit.

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