Pilot-operated type electro-hydraulic proportional valve main valve element position control system and control method

Abstract

The invention discloses a system and a method for controlling the position of a main valve core of a pilot-operated electro-hydraulic proportional valve, and relates to the technical field of pilot-operated electro-hydraulic proportional valve control, the system mainly comprises four modules: (1) a data acquisition and processing module for acquiring the position of the main valve core and the current data of a driver and filtering the data; (2) the control module calculates a target current value of the driver according to a set target value, a feedback value of the data acquisition module and a set control algorithm by adopting a feedforward-feedback composite control strategy; (3) executing a driving module, and adjusting the opening degree of a pilot valve according to the target current value to enable a main valve core to reach an expected value; and the dead zone parameter identification module (4) is used for estimating dead zone parameters of the electro-hydraulic proportional valve on line. According to the method, the problem of high-precision control of the position of the valve element when dead zone parameters of the electro-hydraulic proportional valve are unknown or change can be solved, and self-calibration of the electro-hydraulic proportional valve and self-adaptive control of the position of the valve element are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of pilot-operated electro-hydraulic proportional valve control, and more specifically, to a pilot-operated electro-hydraulic proportional valve main valve core position control system and a control method. Background Art

[0002] As a type of electro-hydraulic proportional valve, the pilot-operated electro-hydraulic proportional valve uses a hydraulic valve bridge composed of high-speed switching valves as a pilot valve, and is matched with a main valve that can output relatively high power. The flow rate can reach 500L / min, and it has obvious energy efficiency advantages. It is widely used in hydraulic control systems in the fields of engineering machinery, special equipment, etc.

[0003] like Figure 1 As shown in the figure, the control system of the pilot-operated electro-hydraulic proportional valve mainly includes: controller, amplifier, proportional solenoid, pilot valve, main valve, displacement sensor and other units. Among them, the displacement sensor collects the actual main valve core position and sets the expected target value of the main valve core position. The controller adjusts the current i of the proportional solenoid on one side according to the set control law. After the proportional solenoid is energized, it outputs electromagnetic force to adjust the valve core opening of the pilot valve, thereby adjusting the pilot oil to drive the main valve core to achieve precise position control.

[0004] In the actual operation process, the oil pressure of the pilot oil is assumed to work at the rated pressure. When the proportional solenoid applies a small current, the main valve core will not be displaced. When the current of the proportional solenoid increases to a certain value, the main valve core begins to move. The area where the applied current of the proportional solenoid is lower than the critical value is usually characterized as a dead zone. Due to the existence of the dead zone, it is difficult for the valve core position control accuracy and dynamic response of the pilot electro-hydraulic proportional valve to achieve high performance, especially for the stable control of small flow. Usually, the dead zone detection method is: disconnect the closed-loop control of the position of the main valve core of the control system, the pilot oil pressure works at the rated pressure value, and only one side of the proportional solenoid gradually increases the current. At the same time, the main valve core position is detected online, and the current value when the main valve core starts to move is recorded. This current value is the current value of the dead zone of the pilot valve on this side; similarly, the current value of the dead zone of the pilot valve on the other side can be obtained.

[0005] In order to improve the control accuracy and dynamic response characteristics of pilot-operated electro-hydraulic proportional valves, domestic and foreign scholars have done a lot of work on the nonlinear characteristics and compensation control of dead zones. For example, Chen Junxiang et al. adopted a flow gain compensation scheme with segmented variable gain to study the linear compensation technology of the middle dead zone of the slide valve, ensuring the linearity of the flow characteristics of the slide valve, but the dead zone was obtained through offline testing and was aimed at a fixed dead zone; Zhang Jiaxu et al. analyzed the influencing factors of the dead zone of the proportional valve and proposed a compensation strategy for zero-position current step and attenuated position command jump, but this control method did not consider the time-varying nature of the dead zone value, and the actual proportional valve controller design is based on the dead zone model or dead zone parameters. When the dead zone changes, the controller may not be applicable to the control system, and the valve core position control accuracy and adjustment time will be greatly affected. In addition, due to the processing errors in the production process, the dead zone compensation value of each proportional valve is also different. Therefore, how to realize intelligent automatic dead zone calibration is of great significance for mass production of products. Summary of the invention

[0006] In order to solve the problem of low valve core position control accuracy caused by the dead zone change of the current pilot electro-hydraulic proportional valve, the present invention proposes a pilot electro-hydraulic proportional valve main valve core position control system and control method, which performs online dead zone parameter estimation of the pilot electro-hydraulic proportional valve, takes into account the time-varying dead zone of the proportional valve, improves the valve core position adjustment speed and control accuracy, and realizes self-calibration of the pilot electro-hydraulic proportional valve and adaptive control of the valve core position.

[0007] In order to achieve the above technical effects, the technical solution of the present invention is as follows:

[0008] In a first aspect, the present application proposes a pilot-operated electro-hydraulic proportional valve main valve core position control system, comprising:

[0009] A data acquisition and processing module is used to acquire the actual main valve core position of the pilot-operated electro-hydraulic proportional valve and the current of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve, and perform data processing;

[0010] The control module takes the error between the expected target value of the main valve core position and the actual main valve core position as input, and uses a feedforward model-feedback model composite control strategy to output a regulating current value of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve;

[0011] A dead zone parameter identification module is used to estimate the dead zone parameters of the pilot-operated electro-hydraulic proportional valve online and transmit them to the control module to update the feedforward model-feedback model composite control strategy;

[0012] The execution drive module adjusts the actual main valve core position of the pilot-operated electro-hydraulic proportional valve according to the adjustment current value of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve, so that the actual main valve core position is stabilized at the expected target value of the main valve core position.

[0013] Preferably, the data processing adopts a high-gain filter method, which is as follows:

[0014]

[0015] Among them, x1(k+1) represents the estimated state of the main valve core position at the k+1th moment, x1(k) represents the estimated state of the main valve core position at the kth moment, x2(k) represents the estimated value of the speed of movement of the main valve core position, y represents the actual main valve core position acquisition value of the pilot electro-hydraulic proportional valve, h represents the sampling interval, and a1, τ, and a2 all represent filter parameters.

[0016] Preferably, in the control module, based on the data processing results and the feedforward model-feedback model composite control strategy, error calculation is also performed, and the process is:

[0017] e(k)=y ref (k)-x1(k)

[0018] Where e(k) represents the expected target value y of the main valve core position at the kth moment ref (k) and the error of the estimated state value x1(k) of the main valve core position at the kth moment; the feedback control current I of the proportional solenoid of the output pilot-operated electro-hydraulic proportional valve at the kth moment c (k), feedback control current I c (k) satisfies the expression:

[0019] I c (k) = k1*e(k)+I s (k)+k3*x2(k)

[0020] Among them, k1 represents the proportional coefficient; k3 represents the differential coefficient; I s (k) represents the integral; when |e(k)|<ε, I s (k) = I s (k-1)+k2*e(k); otherwise, I s (k) = I s (k-1);

[0021]

[0022] Among them, I M Indicates the current limit value;

[0023] Using the feedforward model-feedback model composite control strategy, the process of outputting the adjustment current value I(k) of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve satisfies the expression:

[0024]

[0025] Among them, I L (yref) and I R (yref) are the first side pilot valve feedforward control current and the second side pilot valve feedforward control current respectively.

[0026] Preferably, the pilot-operated electro-hydraulic proportional valve comprises a first-side pilot valve and a second-side pilot valve. The control system of the pilot-operated electro-hydraulic proportional valve disconnects the main valve core position closed-loop control circuit and is in the main valve core position control open-loop state. The second-side pilot valve is closed, and current is applied to the first-side pilot valve. According to the relationship between the several groups of applied currents and the main valve core positions corresponding to the several groups of applied currents, a first-side feedforward model i is established. L , the process is:

[0027] Collect N groups of applied currents and the main valve core positions corresponding to the N groups of applied currents. Each group of applied current i j The corresponding main valve core position y j The first side applied current-main valve core position samples, the set of N groups of samples is expressed as {(i j ,y j )|j=1,2,...,N};

[0028] Take a set of N samples {(i j ,y j )|j=1,2,...,N}, and use the least squares method to perform linear fitting to obtain the first side feedforward model i L , expressed as: i L =1 / a L *y L +b L , where a L 、b L is the first linearity related parameter, i L represents the first side fitting current parameter, y L Indicates the fitting displacement parameters of the main valve core of the pilot valve on the first side.

[0029] Preferably, the pilot-operated electro-hydraulic proportional valve comprises a first-side pilot valve and a second-side pilot valve. The control system of the pilot-operated electro-hydraulic proportional valve disconnects the main valve core position closed-loop control circuit and is in the main valve core position control open-loop state. The first-side pilot valve is closed, and current is applied to the second-side pilot valve. According to the relationship between the several groups of applied currents and the main valve core positions corresponding to the several groups of applied currents, a second-side feedforward model i is established. R , the process is:

[0030] Collect N groups of applied currents and the main valve core positions corresponding to the N groups of applied currents. Each group of applied current i h The corresponding main valve core position y hThe second side applied current-main valve core position sample, the set of N groups of samples is expressed as {(i h ,y h )|h=1,2,...,N};

[0031] Based on the set of N groups of samples, the least squares method is used for linear fitting to obtain the second side feedforward model i R , expressed as: i R =1 / a R *y R +b R , where a R 、a R is the second linearity related parameter, i R represents the fitting current parameter of the second side, y R Indicates the fitting displacement parameters of the main valve core of the second side pilot valve.

[0032] Preferably, the dead zone parameter of the pilot-operated electro-hydraulic proportional valve estimated online by the dead zone parameter identification module includes a first-side pilot valve dead zone parameter and a second-side pilot valve dead zone parameter; the first-side pilot valve dead zone parameter is a first linearity-related parameter;

[0033] The process of estimating the dead zone parameter of the first side pilot valve is as follows:

[0034] The first side applied currents of N groups of pilot valve main valve core positions are collected online when the main valve core positions are stable at the expected target values, forming N groups of first side applied currents constituting currents-main valve core position stable expected targets, expressed as: Where p = 1, 2, ..., N, Indicates the desired target of the main valve core position stability of the pilot valve group p, Indicates that the main valve core position of the pilot valve in group p is stable at the desired target The corresponding actual first side applies current;

[0035] Construct the first cost parameter θ based on the dead zone parameter of the first side pilot valve L =(1 / a L ,b L ) T , and construct the first cost function, the expression is:

[0036]

[0037] When the first cost function is minimum, it satisfies:

[0038]

[0039] The result of the dead zone parameter estimation of the first side pilot valve is They are:

[0040]

[0041]

[0042] Preferably, the second side pilot valve dead zone parameter is a second linearity related parameter; the process of estimating the second side pilot valve dead zone parameter is:

[0043] The second side applied currents of N groups of pilot valve main valve core positions are collected online when they are stable at the desired target, forming N groups of second side applied currents constituting current-main valve core position stable desired target pairs, which are expressed as: Where q = 1, 2, ..., N, Indicates the desired target of the stabilization of the main valve core position of the pilot valve group q, Indicates that the main valve core position of the pilot valve group q is stable at the desired target The corresponding actual second side applies current;

[0044] Construct the second cost parameter θ based on the second side pilot valve dead zone parameter R =(1 / a R ,b R ) T , and construct the second cost function, the expression is:

[0045]

[0046] When the second cost function is minimum, it satisfies:

[0047]

[0048] The result of the dead zone parameter estimation of the second side pilot valve is They are:

[0049]

[0050] In a second aspect, the present application further proposes a method for controlling the position of a valve core of a pilot-operated electro-hydraulic proportional valve, the method comprising:

[0051] S1: Obtain the basic parameters of the pilot-operated electro-hydraulic proportional valve and perform configuration initialization;

[0052] S2: Collecting data from the valve core position sensor and processing the data;

[0053] S3: Determine whether the main valve core position is stable at the expected target value of the main valve core position. If so, record the applied current-main valve core position sample data value at this time to update the set of applied current-main valve core displacement samples and execute S4; otherwise, execute S4;

[0054] S4: Perform online dead zone parameter estimation to obtain an estimated value of the pilot valve dead zone parameter;

[0055] S5: Determine whether the estimated value of the pilot valve dead zone parameter has changed. If so, input the changed estimated value of the dead zone parameter into the control module to update the feedforward model-feedback model composite control strategy; otherwise, return to S2.

[0056] Preferably, the configuration initialization is the initialization of the driver module of the control method execution platform, including: interrupt initialization, CAN communication initialization, PWM setting, and ADC data acquisition setting.

[0057] Preferably, the applied current-main valve core position sample includes a first-side applied current-main valve core position sample and a second-side applied current-main valve core position sample;

[0058] The pilot valve dead zone parameter estimation value includes a first-side pilot valve dead zone parameter estimation value and a second-side pilot valve dead zone parameter estimation value.

[0059] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0060] The present invention proposes a pilot-operated electro-hydraulic proportional valve main valve core position control system and a control method, and constructs a new pilot-operated electro-hydraulic proportional valve core position control system. The control system includes a data acquisition and processing module, a control module, a dead zone parameter identification module, and an execution drive module. The dead zone parameter identification module estimates the dead zone parameters of the pilot-operated electro-hydraulic proportional valve online and transmits them to the control module to update the feedforward model-feedback model composite control strategy, which takes into account the time-varying dead zone of the proportional valve, improves the valve core position adjustment speed and control accuracy, and can realize self-calibration of the pilot-operated electro-hydraulic proportional valve and adaptive control of the valve core position. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 A structural diagram showing the composition of a control system of a conventional pilot-operated electro-hydraulic proportional valve proposed in the background art of the present invention;

[0062] Figure 2 A schematic diagram showing the structure of a pilot-operated electro-hydraulic proportional valve control device according to an embodiment of the present invention;

[0063] Figure 3 A structural diagram showing a pilot-operated electro-hydraulic proportional valve main valve core position control system according to an embodiment of the present invention;

[0064] Figure 4 A schematic flow chart showing a method for controlling the position of a main valve core of a pilot-operated electro-hydraulic proportional valve according to an embodiment of the present invention. DETAILED DESCRIPTION

[0065] The accompanying drawings are only used for illustrative purposes and are not to be construed as limiting the present application;

[0066] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the actual size;

[0067] It is understandable to those skilled in the art that descriptions of certain well-known contents in the drawings may be omitted.

[0068] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0069] The positional relationships described in the drawings are only for illustrative purposes and should not be construed as limiting the present application;

[0070] Example 1

[0071] The present embodiment proposes a main valve core position control system of a pilot-operated electro-hydraulic proportional valve. The pilot-operated electro-hydraulic proportional valve includes a first side pilot valve and a second side pilot valve. In the present embodiment, the main valve core of the pilot-operated electro-hydraulic proportional valve moves between left and right positions. The first side pilot valve refers to the left side pilot valve of the pilot-operated electro-hydraulic proportional valve, and the second side pilot valve refers to the right side pilot valve of the pilot-operated electro-hydraulic proportional valve.

[0072] Figure 2 The schematic diagram of the structure of the pilot-operated electro-hydraulic proportional valve control device proposed in the embodiment of the present invention. The device structurally comprises: an electro-proportional pressure reducing valve 1, a spring 2, a first sealing ring 3, a second sealing ring 4, a third sealing ring 5, a main body 6, a cover plate 7, a gland 8, a probe 9, a mounting housing 10, a bracket 11, a main board 12, a displacement sensor PCB 13, an M12 connector harness 14, a copper pin 15 and a magnet 16.

[0073] Among them, the electric proportional pressure reducing valve 1 controls its own opening degree by receiving the control signal, so as to accurately adjust the pilot pressure of the oil circuit. In the case of power failure or no control signal, the spring 2 ensures that the pressure reducing valve can automatically return to the initial state. The first sealing ring 3, the second sealing ring 4 and the third sealing ring 5 ensure the sealing of the oil circuit or the gas circuit, and effectively prevent the leakage of hydraulic oil. These sealing rings are essential to maintain the stability and reliability of the system. All firmware are fixed on the main body 6 to ensure the structural stability of the module. The cover plate 7 and the gland 8 further fix and protect the electronic components or sensitive components inside the module from interference from the external environment. The probe 9 is directly connected to the main valve core spool for monitoring and transmitting the position information of the valve core. The mounting housing 10 provides protection for the internal components and is provided with a mounting interface with the main valve core transition block to facilitate the integration of the module with the system. The bracket 11 provides necessary support for the internal components to ensure the normal operation of the module under various working conditions. The main board 12 receives the signals of the displacement sensor and the temperature sensor, and adjusts the actuators such as the electric proportional pressure reducing valve according to the preset control logic to achieve precise control of the pilot pressure. The displacement sensor PCB13 is responsible for measuring the displacement of the main valve core and feeding back the measurement data to the main board for precise control. The copper pin 15 and the M12 connector harness 14 constitute the electrical interface of the module, providing a stable electrical connection to ensure the reliability of signal transmission. The magnetic field emitted by the magnet 16 acts on the Hall plate of the displacement sensor PCB13 to output the displacement signal, which is a key component for displacement measurement.

[0074] Figure 3 A schematic diagram of a pilot-operated electro-hydraulic proportional valve main valve core position control system is provided for this embodiment. Figure 3In the figure, A and B both represent working oil circuits, P represents the oil inlet, and T represents the oil return port. The control system includes: a data acquisition and processing module, a control module, a dead zone parameter identification module and an execution drive module; wherein the data acquisition and processing module is used to collect the actual main valve core position of the pilot electro-hydraulic proportional valve and the current of the proportional electromagnet of the pilot electro-hydraulic proportional valve, and perform data processing; the control module takes the error between the expected target value of the main valve core position and the actual main valve core position as input, and uses the feedforward model-feedback model composite control strategy to output the adjustment current value of the proportional electromagnet of the pilot electro-hydraulic proportional valve; the dead zone parameter identification module is used to estimate the dead zone parameters of the pilot electro-hydraulic proportional valve online, and transmit them to the control module to update the feedforward model-feedback model composite control strategy; the execution drive module adjusts the actual main valve core position of the pilot electro-hydraulic proportional valve according to the adjustment current value of the proportional electromagnet of the pilot electro-hydraulic proportional valve, so that the actual main valve core position is stable at the expected target value of the main valve core position. Among them, in actual implementation, for the first side pilot valve and the second side pilot valve, the execution drive module is divided into a first side execution drive module and a second side execution drive module, the first side execution drive module acts on the first side pilot valve, and the second side execution drive module acts on the second side execution drive module.

[0075] The dead zone parameter identification module of the pilot electro-hydraulic proportional valve main valve core position control system proposed in this embodiment estimates the dead zone parameters of the pilot electro-hydraulic proportional valve online and transmits them to the control module to update the feedforward model-feedback model composite control strategy, taking into account the time-varying dead zone of the proportional valve, improving the valve core position adjustment speed and control accuracy, and realizing self-calibration of the pilot electro-hydraulic proportional valve and adaptive control of the valve core position.

[0076] Example 2

[0077] In this embodiment, the data processing of the data acquisition and processing module adopts a high-gain filter method, which is as follows:

[0078]

[0079] Among them, x1(k+1) represents the estimated state of the main valve core position at the k+1th moment, x1(k) represents the estimated state of the main valve core position at the kth moment, x2(k) represents the estimated value of the speed of movement of the main valve core position, y represents the actual main valve core position acquisition value of the pilot electro-hydraulic proportional valve, h represents the sampling interval, and a1, τ, and a2 all represent filter parameters.

[0080] In the control module, under the aforementioned high-gain filter method, that is, based on the data processing results, the feedforward model-feedback model composite control strategy is implemented, and the error calculation is first performed, and the process is:

[0081] e(k)=y ref(k)-x1(k)

[0082] Where e(k) represents the expected target value y of the main valve core position at the kth moment ref (k) and the error of the estimated state value x1(k) of the main valve core position at the kth moment; the feedback control current I of the proportional solenoid of the output pilot-operated electro-hydraulic proportional valve at the kth moment c (k), feedback control current I c (k) satisfies the expression:

[0083] I c (k) = k1*e(k)+I s (k)+k3*x2(k)

[0084] Among them, k1 represents the proportional coefficient; k3 represents the differential coefficient; I s (k) represents the integral; when |e(k)|<ε, I s (k) = I s (k-1)+k2*e(k); otherwise, I s (k) = I s (k-1);

[0085]

[0086] Among them, I M Indicates the current limit value;

[0087] Using the feedforward model-feedback model composite control strategy, the process of outputting the adjustment current value I(k) of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve satisfies the expression:

[0088]

[0089] Among them, I L (yref) and I R (yref) are the first side pilot valve feedforward control current and the second side pilot valve feedforward control current respectively.

[0090] As mentioned above, the pilot-operated electro-hydraulic proportional valve comprises a first-side pilot valve and a second-side pilot valve, and the control system of the pilot-operated electro-hydraulic proportional valve disconnects the main valve core position closed-loop control circuit (i.e. Figure 1 The main valve core position closed-loop control loop shown in the figure is disconnected), the main valve core position control is in the open-loop state, the second side pilot valve is closed, and current is applied to the first side pilot valve. According to the relationship between several groups of applied currents and the main valve core positions corresponding to the several groups of applied currents, the first side feedforward model i is established. L , the process is:

[0091] Collect N groups of applied currents and the main valve core positions corresponding to the N groups of applied currents. Each group of applied current i j The corresponding main valve core position y j The first side applied current-main valve core position samples, the set of N groups of samples is expressed as {(i j ,y j )|j=1,2,...,N};

[0092] Take the set of N groups of samples {(i j ,y j )|j=1,2,...,N}, and use the least squares method to perform linear fitting to obtain the first side feedforward model i L , expressed as: i L =1 / a L *y L +b L , where a L , b L is the first linearity related parameter, i L represents the first side fitting current parameter, y L Indicates the fitting displacement parameters of the main valve core of the pilot valve on the first side.

[0093] Similarly, the control system of the pilot-operated electro-hydraulic proportional valve disconnects the main valve core position closed-loop control circuit (i.e. Figure 1 The main valve core position closed-loop control loop shown in the figure is disconnected), and the main valve core position control is in an open-loop state. The first side pilot valve is closed, and current is applied to the second side pilot valve. According to the relationship between several groups of applied currents and the main valve core positions corresponding to the several groups of applied currents, the second side feedforward model i is established. R , the process is:

[0094] Collect N groups of applied currents and the main valve core positions corresponding to the N groups of applied currents. Each group of applied current i h The corresponding main valve core position y h The second side applied current-main valve core position sample, the set of N groups of samples is expressed as {(i h ,y h )|h=1,2,...,N};

[0095] Based on the set of N groups of samples, the least squares method is used for linear fitting to obtain the second side feedforward model i R , expressed as: i R =1 / a R *y R +b R , where a R 、a R is the second linearity related parameter, i R represents the fitting current parameter of the second side, yR Indicates the fitting displacement parameters of the main valve core of the second side pilot valve.

[0096] In this embodiment, the dead zone parameter of the pilot-operated electro-hydraulic proportional valve estimated online by the dead zone parameter identification module includes a first-side pilot valve dead zone parameter and a second-side pilot valve dead zone parameter; wherein the first-side pilot valve dead zone parameter is a first linearity-related parameter;

[0097] The process of estimating the deadband parameters of the first side pilot valve is:

[0098] The first side applied currents of N groups of pilot valve main valve core positions are collected online when the main valve core positions are stable at the expected target values, forming N groups of first side applied currents constituting currents-main valve core position stable expected targets, expressed as: Where p = 1, 2, ..., N, Indicates the desired target of the main valve core position stability of the pilot valve group p, Indicates that the main valve core position of the pilot valve in group p is stable at the desired target The corresponding actual first side applies current;

[0099] Construct the first cost parameter θ based on the dead zone parameter of the first side pilot valve L =(1 / a L ,b L ) T , and construct the first cost function, the expression is:

[0100]

[0101] When the first cost function is minimum, it satisfies:

[0102]

[0103] The result of the dead zone parameter estimation of the first side pilot valve is They are:

[0104]

[0105] In this embodiment, the dead zone parameter of the second side pilot valve is a second linearity related parameter; the process of estimating the dead zone parameter of the second side pilot valve is:

[0106] The second side applied currents of N groups of pilot valve main valve core positions are collected online when they are stable at the desired target, forming N groups of second side applied currents constituting current-main valve core position stable desired target pairs, which are expressed as: Where q = 1, 2, ..., N, Indicates the desired target of the stabilization of the main valve core position of the pilot valve group q, Indicates that the main valve core position of the pilot valve group q is stable at the desired target The corresponding actual second side applies current;

[0107] Construct the second cost parameter θ based on the second side pilot valve dead zone parameter R =(1 / a R ,b R ) T , and construct the second cost function, the expression is:

[0108]

[0109] When the second cost function is minimum, it satisfies:

[0110]

[0111] The result of the dead zone parameter estimation of the second side pilot valve is They are:

[0112]

[0113] For details, see Figure 3 The control module is based on the feedforward model-feedback model composite control strategy. In the feedforward model control level, the main valve core position expected target value y ref As input, the dead zone parameter estimation module feeds back the dead zone parameter estimation value to the feedforward model control layer and outputs the pilot valve adjustment current value. ref When it is greater than or equal to 0, the expected target value y is calculated based on the main valve core position. ref The dead zone parameter estimation module feeds back the dead zone parameter estimation value to the feedforward model control layer and outputs the pilot valve adjustment current value, which is expressed as: I L =f(y ref );When the main valve core position is expected to be y ref When it is less than 0, the expected target value y is calculated according to the main valve core position. ref The dead zone parameter estimation module feeds back the dead zone parameter estimation value to the feedforward model control layer and outputs the pilot valve adjustment current value, which is expressed as: I R =f(y ref ).

[0114] At the feedback model control level, the main valve core position expected target value y ref The error Err with the actual main valve core position y is used as input, and the output feedback control current I c (k), feedback control current I c (k) is combined with the pilot valve regulating current value to output the regulating current value I(k) of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve, and I(k) acts on the proportional solenoid of the pilot-operated electro-hydraulic proportional valve to regulate the dead zone and the main valve core position;

[0115] The dead zone parameter estimation module uses the final applied current value I(k) and the valve core position sensor collected value y as input to perform dead zone parameter estimation, and inputs the dead zone parameter estimation value into the feedforward control module to update the modeling results between the valve core position of the pilot valve on the first side and the applied current, and the modeling results between the valve core position of the pilot valve on the second side and the applied current; the valve core position sensor collected value y eventually stabilizes at the desired target, and the final applied current value I(k) stabilizes at the actual applied current corresponding to the desired target.

[0116] Example 3

[0117] This embodiment proposes a pilot-operated electro-hydraulic proportional valve spool position control method, see Figure 4 , the method comprising:

[0118] S1: Obtain the basic parameters of the pilot-operated electro-hydraulic proportional valve and perform configuration initialization;

[0119] S2: Collecting data from the valve core position sensor and processing the data;

[0120] S3: Determine whether the main valve core position is stable at the expected target value of the main valve core position. If so, record the applied current-main valve core position sample data value at this time to update the set of applied current-main valve core position sample data value, and execute S4; otherwise, execute S4;

[0121] S4: Perform online dead zone parameter estimation to obtain an estimated value of the pilot valve dead zone parameter;

[0122] S5: Determine whether the estimated value of the pilot valve dead zone parameter has changed. If so, input the changed estimated value of the dead zone parameter into the control module to update the feedforward model-feedback model composite control strategy; otherwise, return to S2.

[0123] In this embodiment, the basic parameters of the pilot-operated electro-hydraulic proportional valve are input into the execution platform as the basic parameters when the control method is executed on the execution platform, including oil pressure, expected target value of the main valve core position, etc. The configuration initialization is the initialization of the drive module of the control method execution platform, including: interrupt initialization, CAN communication initialization, PWM setting, and ADC data acquisition setting.

[0124] In this embodiment, the applied current-main valve core position samples include the first side applied current-main valve core position samples and the second side applied current-main valve core position samples. The pilot valve dead zone parameter estimation value includes the first side pilot valve dead zone parameter estimation value and the second side pilot valve dead zone parameter estimation value.

[0125] In this embodiment, the process of inputting the changed dead zone parameter estimation value into the feedforward control module and updating the feedforward model-feedback model composite control strategy as described in step S5 is as follows: at the feedforward model control level of the feedforward model-feedback model composite control strategy, the expected target value y of the main valve core position is used. ref As input, the dead zone parameter estimation module feeds back the dead zone parameter estimation value to the feedforward model control layer and outputs the pilot valve adjustment current value. ref When it is greater than or equal to 0, the expected target value y is calculated based on the main valve core position. ref The dead zone parameter estimation module feeds back the dead zone parameter estimation value to the feedforward model control layer and outputs the pilot valve adjustment current value, which is expressed as: I L =f(y ref );When the main valve core position is expected to be y ref When it is less than 0, the expected target value y is calculated according to the main valve core position. ref The dead zone parameter estimation module feeds back the dead zone parameter estimation value to the feedforward model control layer and outputs the pilot valve adjustment current value, which is expressed as: I R =f(y ref ). At the feedback model control level, the main valve core position expected target value y ref The error Err with the actual main valve core position y is used as input, and the output feedback control current I c (k), feedback control current I c (k) is combined with the pilot valve regulating current value to output the regulating current value I(k) of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve. I(k) acts on the proportional solenoid of the pilot-operated electro-hydraulic proportional valve to adjust the dead zone and the main valve core position.

[0126] In this embodiment, the basic parameters of the pilot-operated electro-hydraulic proportional valve are obtained from the memory of the execution platform, and the configuration initialization is the initialization of the drive module of the control method execution platform, including: interrupt initialization, CAN communication initialization, PWM setting, and ADC data acquisition setting.

[0127] When the control method proposed in this embodiment is executed, it is implemented based on platform interruption. The interrupt service program adjusts the pilot valve current according to the desired target of the valve core. The communication module in the platform adopts an interrupt receiving mode, and the host computer or external interface module sets the desired target and sends it through CAN communication.

[0128] The embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A pilot-operated electro-hydraulic proportional valve main valve core position control system, characterized in that: include: A data acquisition and processing module is used to acquire the actual main valve core position of the pilot-operated electro-hydraulic proportional valve and the current of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve, and perform data processing; The control module takes the error between the expected target value of the main valve core position and the actual main valve core position as input, and uses a feedforward model-feedback model composite control strategy to output a regulating current value of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve; A dead zone parameter identification module is used to estimate the dead zone parameters of the pilot-operated electro-hydraulic proportional valve online and transmit them to the control module to update the feedforward model-feedback model composite control strategy; The execution drive module adjusts the actual main valve core position of the pilot-operated electro-hydraulic proportional valve according to the adjustment current value of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve, so that the actual main valve core position is stabilized at the expected target value of the main valve core position.

2. The pilot-operated electro-hydraulic proportional valve main valve core position control system according to claim 1, characterized in that: The data processing adopts a high-gain filter method, which is as follows: Among them, x1(k+1) represents the estimated state of the main valve core position at the k+1th moment, x1(k) represents the estimated state of the main valve core position at the kth moment, x2(k) represents the estimated value of the speed of movement of the main valve core position, y represents the actual main valve core position acquisition value of the pilot electro-hydraulic proportional valve, h represents the sampling interval, and a1, τ, and a2 all represent filter parameters.

3. The pilot-operated electro-hydraulic proportional valve main valve core position control system according to claim 2, characterized in that: In the control module, based on the data processing results and the feedforward model-feedback model composite control strategy, error calculation is also performed, and the process is: e(k)=y ref (k)-x1(k) Where e(k) represents the expected target value y of the main valve core position at the kth moment ref (k) and the error of the estimated state value x1(k) of the main valve core position at the kth moment; the feedback control current I of the proportional solenoid of the output pilot-operated electro-hydraulic proportional valve at the kth moment c (k), feedback control current I c (k) satisfies the expression: I c (k)=k1*e(k)+I s(k) +k3*x2(k) Among them, k1 represents the proportional coefficient; k3 represents the differential coefficient; I s (k) represents the integral; when |e(k)|<ε, I s (k) = I s (k-1)+k2*e(k); otherwise, I s (k) = I s (k-1); Among them, I M Indicates the current limit value; Using the feedforward model-feedback model composite control strategy, the process of outputting the adjustment current value I(k) of the proportional solenoid of the pilot-operated electro-hydraulic proportional valve satisfies the expression: Among them, I L (yref) and I R (yref) are the first side pilot valve feedforward control current and the second side pilot valve feedforward control current respectively.

4. The pilot-operated electro-hydraulic proportional valve main valve core position control system according to claim 3, characterized in that: The pilot-operated electro-hydraulic proportional valve comprises a first-side pilot valve and a second-side pilot valve. The control system of the pilot-operated electro-hydraulic proportional valve disconnects the main valve core position closed-loop control circuit and is in the main valve core position control open-loop state. The second-side pilot valve is closed, and current is applied to the first-side pilot valve. According to the relationship between several groups of applied currents and the main valve core positions corresponding to the several groups of applied currents, a first-side feedforward model i is established. L , the process is: Collect N groups of applied currents and the main valve core positions corresponding to the N groups of applied currents. Each group of applied current i j The corresponding main valve core position y j The first side applied current-main valve core position samples, the set of N groups of samples is expressed as {(i j ,y j )|j=1,2,...,N}; Take a set of N samples {(i j ,y j )|j=1,2,...,N}, and use the least squares method to perform linear fitting to obtain the first side feedforward model i L , expressed as: i L =1 / a L *y L +b L , where a L , b L is the first linearity related parameter, i L represents the first side fitting current parameter, y L Indicates the fitting displacement parameters of the main valve core of the pilot valve on the first side.

5. The pilot-operated electro-hydraulic proportional valve main valve core position control system according to claim 3, characterized in that: The pilot-operated electro-hydraulic proportional valve comprises a first-side pilot valve and a second-side pilot valve. The control system of the pilot-operated electro-hydraulic proportional valve disconnects the main valve core position closed-loop control circuit and is in the main valve core position control open-loop state. The first-side pilot valve is closed, and current is applied to the second-side pilot valve. According to the relationship between several groups of applied currents and the main valve core positions corresponding to the several groups of applied currents, a second-side feedforward model i is established. R , the process is: Collect N groups of applied currents and the main valve core positions corresponding to the N groups of applied currents. Each group of applied current i h The corresponding main valve core position y h The second side applied current-main valve core position sample, the set of N groups of samples is expressed as {(i h ,y h )|h=1,2,...,N}; Based on the set of N groups of samples, the least squares method is used for linear fitting to obtain the second side feedforward model i R , expressed as: i R =1 / a R *y R +b R , where a R 、a R is the second linearity related parameter, i R represents the fitting current parameter of the second side, y R Indicates the fitting displacement parameters of the main valve core of the second side pilot valve.

6. The pilot-operated electro-hydraulic proportional valve main valve core position control system according to claim 4, characterized in that: The dead zone parameter of the pilot-operated electro-hydraulic proportional valve estimated online by the dead zone parameter identification module includes a first-side pilot valve dead zone parameter and a second-side pilot valve dead zone parameter; the first-side pilot valve dead zone parameter is a first linearity-related parameter; The process of estimating the dead zone parameter of the first side pilot valve is as follows: The first side applied currents of N groups of pilot valve main valve core positions are collected online when the main valve core positions are stable at the expected target values, forming N groups of first side applied currents constituting currents-main valve core position stable expected targets, expressed as: Where p = 1, 2, ..., N, Indicates the desired target of the main valve core position stability of the pilot valve group p, Indicates that the main valve core position of the pilot valve in group p is stable at the desired target The corresponding actual first side applies current; Construct the first cost parameter θ based on the dead zone parameter of the first side pilot valve L =(1 / a L ,b L ) T , and construct the first cost function, the expression is: When the first cost function is minimum, it satisfies: The result of the dead zone parameter estimation of the first side pilot valve is They are:

7. The pilot-operated electro-hydraulic proportional valve main valve core position control system according to claim 5, characterized in that: The second side pilot valve dead zone parameter is a second linearity related parameter; the process of estimating the second side pilot valve dead zone parameter is: The second side applied currents of N groups of pilot valve main valve core positions are collected online when they are stable at the desired target, forming N groups of second side applied currents constituting current-main valve core position stable desired target pairs, which are expressed as: Where q = 1, 2, ..., N, Indicates the desired target of the stabilization of the main valve core position of the pilot valve group q, Indicates that the main valve core position of the pilot valve group q is stable at the desired target The corresponding actual second side applies current; Construct the second cost parameter θ based on the second side pilot valve dead zone parameter R =(1 / a R ,b R ) T , and construct the second cost function, the expression is: When the second cost function is minimum, it satisfies: The result of the dead zone parameter estimation of the second side pilot valve is They are:

8. A method for controlling the position of a pilot-operated electro-hydraulic proportional valve core, characterized in that: The method comprises: S1: Obtain the basic parameters of the pilot-operated electro-hydraulic proportional valve and perform configuration initialization; S2: Collecting data from the valve core position sensor and processing the data; S3: Determine whether the main valve core position is stable at the expected target value of the main valve core position. If so, record the applied current-main valve core position sample data value at this time to update the set of applied current-main valve core displacement samples and execute S4; otherwise, execute S4; S4: Perform online dead zone parameter estimation to obtain an estimated value of the pilot valve dead zone parameter; S5: Determine whether the estimated value of the pilot valve dead zone parameter has changed. If so, input the changed estimated value of the dead zone parameter into the control module to update the feedforward model-feedback model composite control strategy; otherwise, return to S2.

9. The method for controlling the position of a pilot-operated electro-hydraulic proportional valve core according to claim 8, characterized in that: The configuration initialization is the initialization of the driver module of the control method execution platform, including: interrupt initialization, CAN communication initialization, PWM setting, and ADC data acquisition setting.

10. The method for controlling the position of a pilot-operated electro-hydraulic proportional valve core according to claim 9, characterized in that: The applied current-main valve core position samples include a first side applied current-main valve core position sample and a second side applied current-main valve core position sample; The pilot valve dead zone parameter estimation value includes a first-side pilot valve dead zone parameter estimation value and a second-side pilot valve dead zone parameter estimation value.

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