Online estimation and measurement method and device for pressure drop of valve port of direct-acting electro-hydraulic control valve

Abstract

The invention discloses an online estimation and measurement method and device for the pressure drop of a valve port of a direct-acting electro-hydraulic control valve, and the method comprises the following steps: dividing the direct-acting electro-hydraulic control valve into an electric drive assembly and a slide valve assembly, and respectively building dynamic models of the electric drive assembly and the slide valve assembly about the thrust of a coil; constructing a state-space equation based on unmodeled items in the dynamic model in combination with spring force and hydraulic force; then designing a disturbance observer, and obtaining an integral hydrodynamic model based on valve core displacement and pressure drop fitting; and finally, on-line estimation of the pressure drop is carried out based on an immersion and invariant principle. According to the invention, the use of a pressure sensor is avoided, on one hand, efficient and rapid pressure drop measurement can be realized, and the real-time performance of measurement is ensured; and on the other hand, the pressure drop measuring function is integrated into the direct-acting electro-hydraulic control valve, and a design thought which is fast in response, high in precision, low in cost, light in weight and digital is provided for pressure drop measurement and control of a core control valve in an engineering mechanical hydraulic system.

Description

Technical Field

[0001] The invention relates to the field of engineering machinery, and in particular to an online estimation and measurement method and device for the pressure drop at a valve port of a direct-acting electro-hydraulic control valve. Background Art

[0002] In the context of Industry 4.0, hydraulic components are increasingly integrating intelligent functions such as condition monitoring and fault diagnosis. For hydraulic valves, these intelligent functions require additional pressure sensors to measure the pressure drop at the valve port, but in order to prevent the flow field inside the valve from being affected, the actual arrangement position of the sensor is usually far away from the valve port, which causes errors caused by friction loss and local loss to be introduced into the calculation. In order to accurately measure the pressure drop, the pressure sensor must be installed as close to the valve port as possible in the valve body, and the size of the pressure sensor must be small and compact, which significantly increases the cost and introduces additional potential failure points. With the continuous development and application of electro-hydraulic proportional technology, the trend of intelligence has become more and more obvious, and higher requirements have been put forward for the valve port pressure drop test technology of electro-hydraulic control valves. Summary of the invention

[0003] The present invention aims to address the deficiencies of the prior art and to provide an online estimation and measurement method and device for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve.

[0004] The object of the present invention is achieved through the following technical solution: an online estimation and measurement method for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve, the method comprising the following steps: (1) The direct-acting electro-hydraulic control valve is divided into an electric drive component and a slide valve component, and dynamic models of the electric drive component and the slide valve component with respect to the coil thrust are established respectively; the state space equation is constructed based on the unmodeled items in the dynamic model combined with the spring force and the hydraulic force; (2) Design a disturbance observer and obtain the integral fluid dynamic model based on the valve core displacement and pressure drop fitting; (3) Online estimation of pressure drop based on the immersion and invariance principle.

[0005] Furthermore, the state space equation is as follows: ; in, Represents three state variables, is the valve core displacement, is the current flowing through the coil, is the comprehensive fluid force, representing the unmodeled term, Indicates the spring preload of the slide valve, is the total mass of the spring-mass system, is the viscosity coefficient, is the equivalent resistance of the coil, is the equivalent inductance of the coil, is the force-current coefficient.

[0006] Furthermore, a sliding mode controller is designed in which the valve core acceleration only acts on the control law, and a disturbance observer is designed with estimated error convergence; the details are as follows: ; in, is the convergence rate parameter of the disturbance observer, and z is the auxiliary vector.

[0007] Furthermore, the integrated fluid dynamic model is as follows: ; in, It is a stable fluid force. is the pressure drop across the two metering edges, is the vector of steady-state fluid dynamic coefficients related to pressure to be determined; is the pressure-independent steady-state hydrodynamic coefficient vector to be determined, and are undetermined coefficients of the exponent; all values ​​are obtained through experimental calibration and subsequent processing.

[0008] Furthermore, the specific process of step (3) is as follows: (3.1) Establish an estimated error manifold based on the dynamic model of the direct-acting electro-hydraulic control valve; describe the estimated pressure drop based on the estimated error manifold; (3.2) defining the valve port pressure drop estimation error based on the estimated pressure drop; (3.3) Combined with the integral fluid dynamics model, the control law and sliding mode controller are updated based on the immersion and invariance principle; (3.4) Design the correction term so that the estimation error converges and obtain the estimation law of the original pressure drop estimation term; (3.5) Based on the Lyapunov function, the stability of the controller is considered and the final control law is obtained to achieve online estimation of the pressure drop.

[0009] Furthermore, the estimation error manifold is defined as: ; in is the estimation error correction term introduced, is the raw pressure drop estimate; the total estimated pressure drop Described as: .

[0010] Furthermore, the final control law is: ; in, and is the sliding surface convergence parameter, is the valve core acceleration, is the reference speed signal for the control law, and are the third and fourth order derivatives of the displacement, , .

[0011] In the second aspect, the present invention also provides an online estimation and measurement device for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve. The memory stores executable code, and when the processor executes the executable code, it implements the online estimation and measurement method for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve.

[0012] In a third aspect, the present invention further provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the online estimation and measurement method for the valve port pressure drop of a direct-acting electro-hydraulic control valve.

[0013] In a fourth aspect, the present invention further provides a computer program product, including a computer program, which, when executed by a processor, implements the online estimation and measurement method of the valve port pressure drop of a direct-acting electro-hydraulic control valve.

[0014] Beneficial effects of the present invention: Compared with the prior art, the present invention establishes an integral fluid force model to characterize the mathematical relationship between the integral fluid force and the pressure drop, adopts a time-varying system parameter estimation algorithm, regards the variables in the system model as unknown parameters, and utilizes the immersion and invariance (I&I) principle to calculate the error derivative through the system equilibrium equation, and then integrates to reduce the error, thereby achieving an accurate estimation of the pressure drop; the present invention avoids the use of a pressure sensor, on the one hand, it can achieve efficient and rapid pressure drop measurement, ensuring the real-time measurement; on the other hand, it integrates the pressure drop measurement function into the direct-acting electro-hydraulic control valve, realizes the digital and lightweight design and development of basic hydraulic components, and provides a fast-response, high-precision, low-cost, lightweight, and digital design approach for the pressure drop measurement and control of the core control valve in the hydraulic system of engineering machinery. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 It is a cross-sectional view of a direct-acting electro-hydraulic control valve.

[0017] Figure 2This is the principle block diagram of the voltage drop online estimation method.

[0018] Figure 3 It is a system principle diagram of the test device for testing a hydraulic system of the present invention.

[0019] Figure 4 It is a diagram of an experimental device for testing a hydraulic system according to the present invention.

[0020] Figure 5 It is a schematic diagram of the pressure estimation results under steady-state displacement and steady-state pressure drop conditions.

[0021] Figure 6 It is a schematic diagram of the estimated result and actual pressure drop when the valve core moves from -1mm to 1mm within 0 to 10MPa.

[0022] Figure 7 It is a schematic diagram of pressure estimation results under dynamic displacement and pressure drop conditions.

[0023] Figure 8 is the pressure estimation result under step signal condition.

[0024] Fig. 9 The present invention is a structural diagram of an online estimation and measurement device for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with the accompanying drawings and implementation examples. It should be understood that the specific implementation examples described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The specific implementation method includes the following steps: Step 1, establish the mathematical model of the direct-acting electro-hydraulic control valve system. Direct-acting electro-hydraulic control valves (DECVs) are widely used in current industrial systems and are highly digital components in current hydraulic valves. They are usually powered by solenoids, and the armature of the solenoid overcomes the hydraulic force to control the displacement of the valve core to adjust the flow.

[0027] Step 1-1, according to Newton's second law, the force balance equation of the valve core of the direct-acting electro-hydraulic control valve system is: (1) In formula (1), represents the coil thrust, Indicates the offset spring force, represents the viscosity, represents the inertial force, Indicates fluid power, Indicates an unmodeled term.

[0028] The direct-acting electro-hydraulic control valve system can be regarded as consisting of two parts: the electric drive component and the slide valve component. The electric drive component can be regarded as an electrical system consisting of a resistor and an inductor in series. The dynamic model of the electric drive component is formulated as follows: (2) In formula (2), It is the equivalent voltage across the coil and is used as the controller input; is the equivalent inductance of the coil; is the current flowing through the coil; is the equivalent resistance of the coil; is the coil thrust as described in equation (1), and is the force-current coefficient.

[0029] As for the sliding valve assembly, it can be regarded as a second-order inertial system. The dynamic system obtained by modeling is as follows: (3) in is the total mass of the spring-mass system; is the viscosity coefficient; is the spring stiffness, is the valve core displacement, is the unmodeled dynamics. , the valve core works in the middle position and the flow is 0. Represents the displacement spring preload compression. It is worth noting that the chatter signal is superimposed on the final output signal of the controller, which keeps the valve core quasi-static, so the friction force is regarded as a viscous force.

[0030] Step 1-2, model the fluid force, which usually includes steady fluid force and transient fluid force. The magnitude of the transient fluid force is affected by the total damping length. The influence of is expressed as formula (4): (4) Among them, C d is the flow coefficient, w is the area gradient, due to the symmetrical structural design of the valve core assembly is 0, so the transient fluid force is considered to be 0.

[0031] The total steady-state fluid force for a two-metering edge piston valve is given by the following equation: (5) in It is a stable fluid force; is the velocity coefficient; is the jet angle, is the pressure drop across the two metering edges.

[0032] Choose three state variables Combined with spring force , spring force, and fluid force, and then establish the combined fluid force Finally, the dynamic system can be written as the state space equation: (6) in , which indicates the spring preload of the slide valve.

[0033] Step 2: Establish an integral hydraulic force model based on the hydraulic force measured by the disturbance observer, which is used to be embedded in the online pressure estimation model to realize pressure drop estimation measurement while normally controlling the valve core displacement.

[0034] Step 2-1, the use of disturbance observer requires a model-based control algorithm. The tracking differentiator algorithm using the following equation (7) ensures the continuity of the reference signal: (7) in is the reference position signal used in the control law; is the reference speed signal used in the control law; is a tracking signal and It is to control the conversion speed. Use the differential method to obtain a higher-order reference state than the reference speed order to reduce signal delay.

[0035] Step 2-2, in view of the significant change of hydraulic force within the working range, in order to achieve real-time robustness to valve uncertainty and disturbance, a sliding mode controller with the following form is designed: (8) in and is the sliding surface convergence parameter; , and They are position, velocity and acceleration tracking errors respectively. The results are as follows: (9) Spool acceleration It is also obtained through the differential circuit. As we know from the previous article, its order is high, and there is a certain amount of noise ripple in the value, making it difficult to directly estimate the voltage drop. Therefore, it is only used in the control law. And and are the third and fourth order derivatives of the displacement, respectively.

[0036] Step 2-3, according to the equivalent principle, the control law is designed as follows: (10) in, is the boundary layer flutter parameter, q represents the sliding surface convergence parameter, and s represents the sliding surface; Substituting into (9), the update of (9) is as follows: (11) Step 2-4, design a disturbance observer to converge And define the estimation error According to (6), it can be expressed as: (12) In order to achieve rapid convergence of the disturbance estimate to 0, the designed disturbance observer is shown in the following formula to ensure that the estimation error approaches 0 exponentially: (13) in is the convergence rate parameter of the disturbance observer. Define the auxiliary vector As: (14) Combining (12) and (13), the derivative of (14) is: (15) Therefore, the exponential convergence of the estimation error is guaranteed, and the disturbance observer can be designed as: (16) Step 2-5, define the Lyapunov function as follows: (17) The derivative is: (18) Step 2-6, the main factors affecting the integral fluid force are pressure drop and valve core displacement. The pressure drop condition is selected in the range of 0~12MPa, with a step length of 3 MPa. The valve core displacement condition is selected in the range of -100% to 100% stroke with a step length of 10%. The force model is fitted using the product of the cubic function of the valve core displacement and the low-order function of the pressure drop. The final model is established as follows: (19) In the formula, is the vector of steady-state fluid dynamic coefficients related to pressure to be determined; is the pressure-independent steady-state hydrodynamic coefficient vector to be determined, and are the undetermined coefficients of the exponential. All these values ​​are obtained through experimental calibration and subsequent processing. mm, The first value of is set to 0 to keep the force constant. Based on the measured results, the fitting results are as follows: (20) At this point, the models of integral fluid dynamics and DEVC have been established.

[0037] Step 3: Online estimation of pressure drop based on the immersion and invariance principle (I&I). The I&I principle requires the establishment of an error manifold , is designed to be an invariant attractor manifold through an adaptive control law. This involves ensuring that the pressure drop estimation error trajectory converges within the manifold.

[0038] Step 3-1: The estimation error manifold of the dynamic model based on DECV is defined as: (twenty one) in is the estimation error correction term introduced, is the raw pressure drop estimate. Total estimated pressure drop Described as: (twenty two) Step 3-2: Define the valve port pressure drop estimation error as follows: (twenty three) According to (19) and (20), we note that , and The control law estimated based on the I&I principle is updated as: (twenty four) At the same time, according to (11), the sliding surface derivative Updated as follows: (25) Step 3-3: Next, in the control law, you only need to design ,Right now and , so that Acts as an invariant attracting manifold.

[0039] In order to control the convergence of the law, we can get The derivative of is as follows: (26) if is considered to be slowly changing, i.e. , have: (27) Take the estimation law As (28): (28) Then estimate the derivative of the error Can be updated as follows: (29) Therefore, the estimation error By simply designing a suitable correction term converges to 0 exponentially.

[0040] Take estimate revisions The partial derivative is (30): (30) in is the estimated convergence rate. In other words, the estimated correction term yes: (31) Then the estimation error Exponential convergence: (32) The final estimation law is designed as follows: (33) Step 3-4: Prove the stability of the overall controller by defining the Lyapunov function As shown in (34): (34) Then its derivative is: (35) Therefore, ensure Enough to make The final control law is: (36) Corresponding to the aforementioned embodiment of an online estimation and measurement method for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve, the present invention also provides an embodiment of an online estimation and measurement device for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve.

[0041] See also Fig. 9 An embodiment of the present invention provides an online estimation and measurement device for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve, comprising a memory and one or more processors, wherein the memory stores executable code, and when the processor executes the executable code, it is used to implement an online estimation and measurement method for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve in the above embodiment.

[0042] An embodiment of an online estimation and measurement device for the pressure drop at the port of a direct-acting electro-hydraulic control valve provided by the present invention can be applied to any device with data processing capabilities, and the device with data processing capabilities can be a device or apparatus such as a computer. The device embodiment can be implemented through software, or through hardware or a combination of software and hardware. Taking software implementation as an example, as a device in a logical sense, it is formed by the processor of any device with data processing capabilities in which it is located reading the corresponding computer program instructions in the non-volatile memory into the internal memory for execution. From a hardware perspective, if Fig. 9 As shown, it is a hardware structure diagram of any device with data processing capability where an online estimation and measurement device for the valve port pressure drop of a direct-acting electro-hydraulic control valve provided by the present invention is located. Fig. 9 In addition to the processor, memory, network interface, and non-volatile memory shown, any device with data processing capabilities in which the apparatus in the embodiments is located may also include other hardware, generally based on the actual functions of the device with data processing capabilities, which will not be described in detail.

[0043] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0044] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of the present invention. Ordinary technicians in this field can understand and implement it without paying creative work.

[0045] An embodiment of the present invention further provides a computer-readable storage medium having a program stored thereon. When the program is executed by a processor, an online estimation and measurement method for the valve port pressure drop of a direct-acting electro-hydraulic control valve in the above embodiment is implemented.

[0046] The computer-readable storage medium may be an internal storage unit of any device with data processing capability described in any of the aforementioned embodiments, such as a hard disk or a memory. The computer-readable storage medium may also be an external storage device of any device with data processing capability, such as a plug-in hard disk, a smart media card (SMC), an SD card, a flash card, etc. equipped on the device. Furthermore, the computer-readable storage medium may also include both an internal storage unit and an external storage device of any device with data processing capability. The computer-readable storage medium is used to store the computer program and other programs and data required by any device with data processing capability, and may also be used to temporarily store data that has been output or is to be output.

[0047] The present invention also provides a computer program product, including a computer program, which, when executed by a processor, implements the online estimation and measurement method for the valve port pressure drop of a direct-acting electro-hydraulic control valve.

[0048] The above embodiments are used to illustrate the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. An online estimation and measurement method for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve, characterized in that: The method comprises the following steps: (1) The direct-acting electro-hydraulic control valve is divided into an electric drive component and a slide valve component, and dynamic models of the electric drive component and the slide valve component with respect to the coil thrust are established respectively; the state space equation is constructed based on the unmodeled items in the dynamic model combined with the spring force and the hydraulic force; (2) Design a disturbance observer to obtain the hydraulic force and unmodeled terms, and obtain the integral hydraulic force model based on the valve core displacement and pressure drop fitting; (3) Online estimation of pressure drop based on the immersion and invariance principle.

2. The method for online estimation and measurement of the pressure drop at the valve port of a direct-acting electro-hydraulic control valve according to claim 1 is characterized in that: The state space equation is as follows: ； in, Represents three state variables, is the valve core displacement, is the current flowing through the coil, is the comprehensive fluid force, representing the unmodeled term, Indicates the spring preload of the slide valve, is the total mass of the spring-mass system, is the viscosity coefficient, is the equivalent resistance of the coil, is the equivalent inductance of the coil, is the force-current coefficient.

3. The method for online estimation and measurement of the pressure drop at the valve port of a direct-acting electro-hydraulic control valve according to claim 1 is characterized in that: Design a sliding mode controller in which the spool acceleration acts only on the control law, and design a disturbance observer with convergence estimation error; the details are as follows: ； in, is the convergence speed parameter of the disturbance observer, and z is the auxiliary vector.

4. The method for online estimation and measurement of the pressure drop at the valve port of a direct-acting electro-hydraulic control valve according to claim 1, characterized in that: The integrated hydrodynamic model is as follows: ； in, It is a stable fluid force. is the pressure drop across the two metering edges, is the vector of steady-state fluid dynamic coefficients related to pressure to be determined; is the pressure-independent steady-state hydrodynamic coefficient vector to be determined, and are undetermined coefficients of the exponent; all values ​​are obtained through experimental calibration and subsequent processing.

5. The method for online estimation and measurement of the pressure drop at the valve port of a direct-acting electro-hydraulic control valve according to claim 1, characterized in that: The specific process of step (3) is as follows: (3.1) Establish an estimated error manifold based on the dynamic model of the direct-acting electro-hydraulic control valve; describe the estimated pressure drop based on the estimated error manifold; (3.2) defining the valve port pressure drop estimation error based on the estimated pressure drop; (3.3) Combined with the integral fluid dynamics model, the control law and sliding mode controller are updated based on the immersion and invariance principle; (3.4) Design the correction term so that the estimation error converges and obtain the estimation law of the original pressure drop estimation term; (3.5) Based on the Lyapunov function, the stability of the controller is considered and the final control law is obtained to achieve online estimation of the pressure drop.

6. The method for online estimation and measurement of the pressure drop at the valve port of a direct-acting electro-hydraulic control valve according to claim 1, characterized in that: The estimation error manifold is defined as: ； in is the estimation error correction term introduced, is the raw pressure drop estimate; the total estimated pressure drop Described as: 。 7. The method for online estimation and measurement of the pressure drop at the valve port of a direct-acting electro-hydraulic control valve according to claim 1, characterized in that: The final control law is: ； in, and is the sliding surface convergence parameter, is the valve core acceleration, is the reference speed signal for the control law, and are the third and fourth order derivatives of the displacement, , .

8. An online estimation and measurement device for the pressure drop at the valve port of a direct-acting electro-hydraulic control valve, comprising a memory and one or more processors, wherein the memory stores executable code, characterized in that: When the processor executes the executable code, an online estimation and measurement method for the valve port pressure drop of a direct-acting electro-hydraulic control valve according to any one of claims 1 to 7 is implemented.

9. A computer-readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, an online estimation and measurement method for the valve port pressure drop of a direct-acting electro-hydraulic control valve as described in any one of claims 1 to 7 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, an online estimation and measurement method for the valve port pressure drop of a direct-acting electro-hydraulic control valve as described in any one of claims 1 to 7 is implemented.

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