A method, system and device for controlling a cylinder based on a reversing valve

Abstract

The present application provides a cylinder control method, system and device based on a reversing valve, which calculates the difference between the real-time position of the cylinder before the cylinder is triggered and the preset reference position as the first control deviation value, and then compares it with the reference value, and then supplies power to the reversing valve and controls the cylinder to rise or fall according to the power supply result; and calculates the difference between the real-time position of the cylinder in the cylinder trigger state and the preset reference position as the second control deviation value to compare with the first cylinder switch line, and closes the reversing valve according to the comparison result to control the cylinder movement speed to zero; finally, obtains the static deviation value, and calculates the second cylinder switch line based on the static deviation value, and replaces the first cylinder switch line with the second cylinder switch line, so that the static deviation value at the next moment is less than the current moment. The present application can ensure that the static deviation value when the cylinder movement speed is zero becomes smaller and smaller by iterative learning of the cylinder switch line, thereby improving the accuracy of the cylinder positioning control system.

Description

Technical Field

[0001] The present application relates to the technical field of metal casting, and in particular to a method, system and device for controlling an oil cylinder based on a reversing valve. Background Art

[0002] Iron and steel materials are one of the basic materials of human society, and they promote the development of society. In the process of iron and steel metallurgical production, continuous casting technology plays an important role in the manufacturing process of steel products as a connecting production process. Efficient continuous casting is an important direction of continuous casting production technology. Efficient continuous casting technology is based on high casting speed, high quality and defect-free billet production, and realizes high continuous casting rate, high operating rate and low cost continuous casting system technology. The optimization design and control of the fan-shaped segment roll gap is an important process in continuous casting production. The traditional roll gap control system is basically completed by servo valve, proportional valve and high-speed switch valve to continuously control the medium flow. Its valve body structure is complex, the oil cleanliness requirements are high, and the price is expensive. The reversing valve (directional control valve, referred to as DCV) is a low-cost valve with low environmental requirements, simple control and long service life. If DCV is used for fan-shaped segment roll gap control, it can effectively reduce the enterprise's initial project investment and later operation and maintenance costs while ensuring the process control accuracy, which has positive significance for the enterprise to reduce costs and increase efficiency.

[0003] As the core component of the control system, DCV has the problems of low control accuracy and system "jitter" due to its non-continuous control, low switching frequency, and large time lag in control output.

[0004] In addition, there are few studies on the DCV valve-controlled hydraulic cylinder position control system and control methods. Moreover, due to the large mass of the continuous casting sector equipment, the large number of hydraulic cylinders controlled simultaneously, and the high control accuracy requirements, the control is required to be stable, the hydraulic system is simple, and the algorithm cannot be too complicated. Summary of the invention

[0005] In view of the shortcomings of the prior art mentioned above, the purpose of the present application is to provide a cylinder control method, system and device based on a reversing valve, which is used to solve the problems of low control accuracy and system "jitter" commonly existing in the DCV-based cylinder positioning control system in the prior art.

[0006] To achieve the above objectives and other related objectives, the present application provides a cylinder control method based on a reversing valve, the method comprising the following steps:

[0007] Calculate the difference between the real-time position of the cylinder before the cylinder is in the triggered state and the preset reference position, and record it as the first control deviation value;

[0008] The first control deviation value is compared with a first reference value and a second reference value respectively, and according to the comparison result, the oil cylinder trigger state is entered, the reversing valve is powered, and the oil cylinder is controlled to rise or fall according to the power supply result of the reversing valve; wherein the absolute values ​​of the first reference value and the second reference value are the same, and the sum of the first reference value and the second reference value is zero;

[0009] Calculate the difference between the real-time position of the cylinder and the preset reference position in the cylinder trigger state, and record it as the second control deviation value;

[0010] Compare the second control deviation value with the first cylinder switch line respectively, and close the reversing valve according to the comparison result to control the cylinder movement speed to zero;

[0011] Obtain a static deviation value when the cylinder movement speed is zero, calculate a second cylinder switch line based on the static deviation value, and replace the first cylinder switch line with the second cylinder switch line, so that the static deviation value when the actual cylinder movement speed is zero at the next moment is smaller than that at the current moment.

[0012] Optionally, if the first reference value is a negative value and the second reference value is a positive value, the first control deviation value is compared with the first reference value and the second reference value respectively, and the oil cylinder triggering state is entered according to the comparison result, the reversing valve is powered, and the process of controlling the oil cylinder to rise or fall according to the power supply result of the reversing valve includes:

[0013] Comparing the first control deviation value with a first reference value and a second reference value respectively;

[0014] If the first control deviation value is less than the first reference value, the oil cylinder enters a positive trigger state, the reversing valve is positively powered, and the oil cylinder is controlled to rise;

[0015] If the first control deviation value is greater than the second reference value, the oil cylinder enters a negative trigger state, the reversing valve is negatively powered, and the oil cylinder is controlled to descend;

[0016] If the first control deviation value is greater than or equal to the first reference value and less than or equal to the second control deviation value, the cylinder trigger state is not entered, the reversing valve is de-energized, and the difference between the real-time position of the cylinder before the cylinder trigger state and the preset reference position is recalculated.

[0017] Optionally, the process of obtaining a static deviation value when the cylinder movement speed is zero and calculating the second cylinder switch line based on the static deviation value includes:

[0018] Get the first cylinder switch line and the static deviation value

[0019] According to the first oil cylinder switch line and the static deviation value Perform iterative learning to obtain the second cylinder switch line have:

[0020]

[0021] Where i is the number of cylinder control times, i = 0, 1, 2, 3 ... n; when i = 0, it means the first cylinder control, at this time the first cylinder switch line Preset the cylinder switch line in the initial state;

[0022] k is the adaptive learning factor.

[0023] Optionally, the process of obtaining the static deviation value when the cylinder movement speed is zero includes:

[0024] Get the movement distance of the cylinder from the time the reversing valve is powered off to the time the cylinder movement stops completely, recorded as the creeping distance δ crawl ,have:

[0025]

[0026] Get the deviation value when the reversing valve is powered off, recorded as e stop ;

[0027] According to the creeping distance δ crawl and the deviation value e when the reversing valve is powered off stop Calculate the static deviation value e when the cylinder movement speed is zero ss ,have:

[0028] e ss =δ crawl +e stop ;

[0029] Where, t crawl v is the creeping time from when the reversing valve is powered off to when the cylinder stops moving completely, crawl (t) is the creeping speed of the cylinder after the reversing valve is powered off.

[0030] Optionally, the dynamic equation of the reversing valve is as follows:

[0031]

[0032] In the formula, F v is the electromagnetic attraction force after the solenoid is powered on; m v is the mass of the moving parts; C is the viscous damping coefficient; k s is the stiffness coefficient of the pull-back spring; x v is the valve core displacement; is the first-order derivative of the valve core displacement; is the second-order derivative of the valve core displacement.

[0033] Optionally, the reversing valve comprises a solenoid, a valve core and a return spring. The solenoid generates electromagnetic force after being powered on, and after interacting with the return spring, opens or closes the valve core.

[0034] The present application also provides a cylinder control system based on a reversing valve, the system comprising:

[0035] A first control deviation module is used to calculate the difference between the real-time position of the cylinder before the cylinder is in a triggered state and a preset reference position, which is recorded as a first control deviation value;

[0036] a first comparison module, configured to compare the first control deviation value with a first reference value and a second reference value respectively; wherein the absolute values ​​of the first reference value and the second reference value are the same, and the sum of the first reference value and the second reference value is zero;

[0037] A first oil cylinder control module, used for entering an oil cylinder triggering state according to a comparison result of the first comparison module, supplying power to the reversing valve, and controlling the oil cylinder to rise or fall according to a power supply result of the reversing valve;

[0038] A second control deviation module is used to calculate the difference between the real-time position of the cylinder and the preset reference position in the cylinder trigger state, which is recorded as a second control deviation value;

[0039] A second comparison module compares the second control deviation value with the first cylinder switch line respectively;

[0040] A second oil cylinder control module, used for closing the reversing valve according to the comparison result of the second comparison module, and controlling the movement speed of the oil cylinder to zero;

[0041] The cylinder iteration control module is used to obtain the static deviation value when the cylinder movement speed is zero, calculate the second cylinder switch line based on the static deviation value, and replace the first cylinder switch line with the second cylinder switch line so that the static deviation value when the actual movement speed of the cylinder is zero at the next moment is smaller than the current moment.

[0042] Optionally, if the first reference value is a negative value and the second reference value is a positive value, the first cylinder control module enters the cylinder trigger state according to the comparison result of the first comparison module, supplies power to the reversing valve, and controls the cylinder to rise or fall according to the power supply result of the reversing valve. The process includes:

[0043] If the first control deviation value is less than the first reference value, the oil cylinder enters a positive trigger state, the reversing valve is positively powered, and the oil cylinder is controlled to rise;

[0044] If the first control deviation value is greater than the second reference value, the oil cylinder enters a negative trigger state, the reversing valve is negatively powered, and the oil cylinder is controlled to descend;

[0045] If the first control deviation value is greater than or equal to the first reference value and less than or equal to the second control deviation value, the cylinder trigger state is not entered, the reversing valve is de-energized, and the difference between the real-time position of the cylinder before the cylinder trigger state and the preset reference position is recalculated.

[0046] Optionally, the process in which the cylinder iteration control module obtains a static deviation value when the cylinder movement speed is zero, and calculates the second cylinder switch line based on the static deviation value includes:

[0047] Get the first cylinder switch line and the static deviation value

[0048] According to the first oil cylinder switch line and the static deviation value Perform iterative learning to obtain the second cylinder switch line have:

[0049]

[0050] Where i is the number of cylinder control times, i = 0, 1, 2, 3 ... n; when i = 0, it means the first cylinder control, at this time the first cylinder switch line Preset the cylinder switch line in the initial state;

[0051] k is the adaptive learning factor.

[0052] Optionally, the process of the cylinder iteration control module acquiring the static deviation value when the cylinder movement speed is zero includes:

[0053] Get the movement distance of the cylinder from the time the reversing valve is powered off to the time the cylinder movement stops completely, recorded as the creeping distance δ crawl ,have:

[0054]

[0055] Get the deviation value when the reversing valve is powered off, recorded as e stop ;

[0056] According to the creeping distance δ crawl and the deviation value e when the reversing valve is powered off stop Calculate the static deviation value e when the cylinder movement speed is zero ss ,have:

[0057] ess =δ crawl +e stop ;

[0058] Where, t crawl v is the creeping time from when the reversing valve is powered off to when the cylinder stops moving completely, crawl (t) is the creeping speed of the cylinder after the reversing valve is powered off.

[0059] The present application also provides a device for implementing the cylinder control method based on a reversing valve as described in any of the above, the device includes an outer arc frame and an inner arc frame, and a positioning cylinder is provided on the inner arc frame. The positioning cylinder is used for closed-loop adjustment of the roll gap value between the outer arc frame and the inner arc frame to control the thickness of the ingot.

[0060] Optionally, the positioning cylinder includes a position sensor and a reversing valve hydraulic valve station; the reversing valve hydraulic valve station includes an electromagnetic reversing valve, a hydraulic lock, a throttling damping hole and a relief valve, the oil outlet of the electromagnetic reversing valve is connected to the cavity of the cylinder through the hydraulic lock and the throttling damping hole, the position sensor is installed on the piston rod of the cylinder, and is used to measure the real-time output displacement of the cylinder; the relief valve is used to maintain the stability of the cylinder pressure and to perform pressure protection on the cylinder.

[0061] As described above, the present application provides a method, system and device for controlling a cylinder based on a reversing valve, which have the following beneficial effects:

[0062] The present application calculates the difference between the real-time position of the cylinder before the cylinder is triggered and the preset reference position as the first control deviation value; then compares the first control deviation value with the first reference value and the second reference value respectively, and enters the cylinder trigger state according to the comparison result, supplies power to the reversing valve, and controls the cylinder to rise or fall according to the power supply result of the reversing valve; wherein the absolute value of the first reference value is the same as the absolute value of the second reference value, and the sum of the first reference value and the second reference value is zero; then calculates the difference between the real-time position of the cylinder and the preset reference position in the cylinder trigger state, and records it as the second control deviation value; then compares the second control deviation value with the first cylinder switch line respectively, and closes the reversing valve according to the comparison result to control the cylinder movement speed to zero; finally, obtains the static deviation value when the cylinder movement speed is zero, and calculates the second cylinder switch line based on the static deviation value, and replaces the first cylinder switch line with the second cylinder switch line, so that the static deviation value when the actual movement speed of the cylinder is zero at the next moment is smaller than the current moment. It can be seen that the present application performs iterative learning of the cylinder switch line when the cylinder is completely finished, and replaces the cylinder switch line of the previous moment with the iteratively learned cylinder switch line, thereby ensuring that the static deviation value when the cylinder movement speed is zero is getting smaller and smaller, thereby improving the accuracy of the cylinder positioning control system. In addition, the present application only allows the reversing valve to switch once each time the cylinder tracking control is performed, thereby effectively reducing the switching frequency of the reversing valve, solving the "jittering" problem that occurs in the prior art, and reducing the instantaneous impact of the reversing valve on the valve control system due to the opening / closing of the valve, which is beneficial to extending the service life of the equipment. In addition, the present application uses a simple and economical ordinary reversing valve to replace complex and expensive servo valves, proportional valves, high-speed switch valves, etc., which can not only achieve the roller gap precision control of the continuous casting fan segment, but also effectively reduce the enterprise's initial project investment and later operation and maintenance costs while ensuring the process control accuracy and system stability, which has positive significance for the enterprise to reduce costs and increase efficiency. At the same time, the control algorithm of the present application is simple and does not require complex modeling of the hydraulic system, thereby reducing the requirements for controller performance. It is particularly suitable for the fan-shaped segment roll gap control process and can be used in an application environment where dozens of cylinders are controlled simultaneously by one PLC (Programmable Logic Controller, PLC for short). BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 A schematic flow chart of a cylinder control method based on a reversing valve provided in an embodiment of the present application;

[0064] Figure 2 A schematic flow chart of a cylinder control method based on a reversing valve provided in another embodiment of the present application;

[0065] Figure 3A schematic diagram of the basic structure of a reversing valve provided in an embodiment of the present application;

[0066] Figure 4 A dynamic response curve diagram of a valve core in a reversing valve provided in an embodiment of the present application;

[0067] Figure 5 A schematic diagram of a cylinder control based on a reversing valve provided in an embodiment of the present application;

[0068] Figure 6 A schematic diagram of a phase plane analysis provided in an embodiment of the present application;

[0069] Figure 7 A phase plane motion trajectory diagram provided by an embodiment of the present application;

[0070] Figure 8 A schematic diagram of the performance analysis of the oil cylinder position control provided in one embodiment of the present application;

[0071] Fig. 9 A schematic diagram of the hardware structure of a cylinder control system based on a reversing valve provided in an embodiment of the present application;

[0072] Fig.10 A schematic diagram of the structure of a cylinder control device based on a reversing valve provided in an embodiment of the present application;

[0073] Fig.11 An embodiment of the present application provides Fig.10 Part of the hydraulic control system schematic diagram. DETAILED DESCRIPTION

[0074] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0075] It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present application in a schematic manner, and therefore the drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0076] See also Figure 1 This embodiment provides a cylinder control method based on a reversing valve, the method comprising the following steps:

[0077] S110, calculating the difference between the real-time position of the oil cylinder before the oil cylinder is in a triggered state and the preset reference position, and recording it as a first control deviation value;

[0078] S120, compare the first control deviation value with the first reference value and the second reference value respectively, and enter the oil cylinder trigger state according to the comparison result, power the reversing valve, and control the oil cylinder to rise or fall according to the power supply result of the reversing valve; wherein the absolute value of the first reference value is the same as the absolute value of the second reference value, and the sum of the first reference value and the second reference value is zero. That is, if the first reference value is a negative value, the second reference value is a positive value; if the first reference value is a positive value, the second reference value is a negative value. As an example, in this embodiment, the absolute value of the first reference value and the second reference value can be the absolute value of the reversing valve control dead zone.

[0079] S130, calculating the difference between the real-time position of the oil cylinder in the oil cylinder trigger state and the preset reference position, and recording it as a second control deviation value;

[0080] S140, comparing the second control deviation value with the first cylinder switch line respectively, and closing the reversing valve according to the comparison result to control the cylinder movement speed to zero;

[0081] S150, obtaining a static deviation value when the cylinder movement speed is zero, and calculating a second cylinder switch line based on the static deviation value, and replacing the first cylinder switch line with the second cylinder switch line, so that the static deviation value when the actual cylinder movement speed is zero at the next moment is smaller than that at the current moment.

[0082] It can be seen that this embodiment performs iterative learning of the cylinder switch line when the cylinder is completely finished, and replaces the cylinder switch line of the previous moment with the iteratively learned cylinder switch line, so as to ensure that the static deviation value when the cylinder movement speed is zero is getting smaller and smaller, thereby improving the accuracy of the cylinder positioning control system. In addition, this embodiment only allows the reversing valve to switch once each time the cylinder tracking control is performed, thereby effectively reducing the switching frequency of the reversing valve, solving the "chattering" problem that occurs in the prior art, reducing the instantaneous impact of the reversing valve on the valve control system due to the opening / closing of the reversing valve, and is conducive to extending the service life of the equipment. In addition, this embodiment uses a simple and economical ordinary reversing valve to replace complex and expensive servo valves, proportional valves, high-speed switch valves, etc., which can not only realize the roller gap precision control of the continuous casting fan segment, but also effectively reduce the enterprise's initial project investment and later operation and maintenance costs while ensuring the process control accuracy and system stability, which has positive significance for the enterprise to reduce costs and increase efficiency. At the same time, the control algorithm of this embodiment is simple and does not require complex modeling of the hydraulic system, thereby reducing the requirements for controller performance. It is particularly suitable for the fan-shaped segment roll gap control process and can be applied to the application environment where a PLC controls dozens of cylinders at the same time.

[0083] In an exemplary embodiment, if the first reference value is a negative value and the second reference value is a positive value, then step S120 compares the first control deviation value with the first reference value and the second reference value respectively, and enters the oil cylinder trigger state according to the comparison result, supplies power to the reversing valve, and controls the oil cylinder to rise or fall according to the power supply result of the reversing valve. The process includes: comparing the first control deviation value with the first reference value and the second reference value respectively; if the first control deviation value is less than the first reference value, then entering the oil cylinder positive trigger state, supplying power to the reversing valve positively, and controlling the oil cylinder to rise. If the first control deviation value is greater than the second reference value, then entering the oil cylinder negative trigger state, supplying power to the reversing valve negatively, and controlling the oil cylinder to fall. If the first control deviation value is greater than or equal to the first reference value and less than or equal to the second control deviation value, then not entering the oil cylinder trigger state, and de-energizing the reversing valve, and recalculating the difference between the real-time position of the oil cylinder and the preset reference position before the oil cylinder trigger state.

[0084] In an exemplary embodiment, step S150 obtains the static deviation value when the cylinder movement speed is zero, and the process of calculating the second cylinder switch line based on the static deviation value includes: obtaining the first cylinder switch line and the static deviation value According to the first oil cylinder switch line and the static deviation value Perform iterative learning to obtain the second cylinder switch line have: Where i is the number of cylinder control times, i = 0, 1, 2, 3 ... n; k is the adaptive learning factor. As an example, in this embodiment, the first cylinder switch line Indicates the cylinder switch line when the i-th cylinder is controlled, the second cylinder switch line It represents the cylinder switch line after iterative learning based on the cylinder switch line during the i-th cylinder control. For example, when i=0, it means the first or first cylinder control. At this time, the first cylinder switch line Indicates the preset oil cylinder switch line in the initial state. The preset oil cylinder switch line in the initial state can be set according to actual conditions, and this embodiment does not impose a specific numerical limit.

[0085] According to the above records, in an exemplary embodiment, the process of obtaining the static deviation value when the cylinder movement speed is zero in step S150 includes: obtaining the movement distance of the cylinder from the time when the reversing valve is powered off to the time when the cylinder movement stops completely, recorded as the creeping distance δ crawl ,have: Get the deviation value when the reversing valve is powered off, recorded as e stop ; According to the crawling distance δ crawl and the deviation value e when the reversing valve is powered off stop Calculate the static deviation value e when the cylinder movement speed is zero ss , there are: e ss =δ crawl +e stop Where, t crawl v is the creeping time from when the reversing valve is powered off to when the cylinder stops moving completely, crawl (t) is the creeping speed of the cylinder after the reversing valve is powered off.

[0086] In an exemplary embodiment, the dynamic equation of the reversing valve is as follows: In the formula, F v is the electromagnetic attraction force after the solenoid is powered on; m v is the mass of the moving parts; C is the viscous damping coefficient; k s is the stiffness coefficient of the pull-back spring; x v is the valve core displacement; is the first-order derivative of the valve core displacement; is the second-order derivative of the valve core displacement. Specifically, the reversing valve comprises a solenoid, a valve core and a pull-back spring, and the solenoid generates an electromagnetic force after being powered on, and after interacting with the pull-back spring, the valve core is opened or closed.

[0087] In another exemplary embodiment, Figure 2 As shown, the embodiment of the present application also provides a cylinder control method based on a reversing valve, comprising the following steps:

[0088] S101, determine whether the control deviation e(t) is less than the control dead zone -δ. If the control deviation e(t) is less than the control dead zone -δ, that is, e(t)<-δ, then proceed to S201; if the control deviation e(t) is greater than the control dead zone -δ, then determine whether the control deviation e(t) is greater than the control dead zone δ. If the control deviation e(t) is greater than the control dead zone δ, that is, e(t)>δ, then proceed to S301; if the control deviation e(t) is within the control dead zone, that is, |e(t)|≤δ, then DCV power is lost (u(t)=u0), and the judgment of S101 is repeated to continue to determine whether the control deviation e(t) is less than the control dead zone -δ. In this embodiment, the control deviation e(t) in step S101 can also be the first control deviation value in other embodiments, the control dead zone -δ can also be the first reference value in other embodiments, and the control dead zone δ can also be the second reference value in other embodiments.

[0089] S201, turn on DCV to get power in the forward direction, u(t) = u + , the oil cylinder rises and enters S202;

[0090] S202, determine whether the control deviation e(t) is greater than the oil cylinder rising switch line -e stop+ , that is, e(t)<-e stop+ No, keep DCV energized in the forward direction; yes, go to S203; wherein, in this embodiment, the control deviation e(t) in step S202 may also be the second control deviation value in other embodiments.

[0091] S203, DCV power failure, u(t)=u0, transfer to S204;

[0092] S204, determine whether the actual movement speed v(t) of the oil cylinder is 0, v(t=0, no, continue to wait; yes, go to S205;

[0093] S205, record the static deviation value e at this time ss , and perform a switch line e stop+ The iterative learning of the switch line is as follows:

[0094]

[0095] Wherein, k is the adaptive learning factor. In this embodiment, the switch line in step S205 It can also be the first oil cylinder switch line in other embodiments, after iteration It may also be the second oil cylinder switch line in other embodiments.

[0096] S301, turn on DCV negative power, u(t) = u- , the oil cylinder descends and enters S302;

[0097] S302: Determine whether the control deviation e(t) is less than the cylinder lowering switch line e stop- , that is, e(t)>e stop- No, keep DCV negatively energized; yes, go to S303; wherein, in this embodiment, the control deviation e(t) in step S302 may also be the second control deviation value in other embodiments.

[0098] S303, DCV power failure, u(t)=u0, go to S304;

[0099] S304, determine whether the actual movement speed v(t) of the oil cylinder is 0, v(t=0, no, continue to wait; yes, go to S305;

[0100] S305, record the static deviation value e at this time ss , and perform a switch line e stop- The iterative learning of the switch line is as follows:

[0101]

[0102] Wherein, k is the adaptive learning factor. In this embodiment, the switch line in step S205 It can also be the first oil cylinder switch line in other embodiments, after iteration It may also be the second oil cylinder switch line in other embodiments.

[0103] Specifically, since the DCV is the core control component in the entire cylinder control process, the opening and closing time of the DCV has an important influence on the dynamic and static characteristics of the valve, and directly determines the stability and accuracy of the cylinder control process. Therefore, this embodiment can analyze the switching characteristics of the DCV. The basic structure of the reversing valve DCV in this embodiment is as follows Figure 3 As shown, Figure 3 It is the basic structure of a typical solenoid-type three-position four-way electromagnetic reversing valve, which consists of a housing 1, two solenoids 2, a valve core 3 and two pull-back springs 4. The valve core is opened or closed by the interaction between the electromagnetic force generated by the solenoid after power is turned on and the pull-back spring, so that the DCV is energized or de-energized. The simple dynamic equation of the DCV is as follows:

[0104]

[0105] In the formula, F v is the electromagnetic attraction force after the solenoid is powered on; m v is the mass of the moving parts; C is the viscous damping coefficient; k sis the stiffness coefficient of the pull-back spring; x v is the valve core displacement; is the first-order derivative of the valve core displacement; is the second-order derivative of the valve core displacement.

[0106] Among them, the electromagnet voltage equation is as follows:

[0107]

[0108] Where U is the coil terminal voltage; R is the coil internal resistance; L is the coil inductance; i is the coil current.

[0109] The switching dynamic process curve of DCV under rectangular wave excitation is as follows Figure 4 As shown in the figure, the electromagnet's attraction and release process is divided into five working stages, corresponding to the three movement processes of the valve core: 1) Electrical delay stage t1. When the power is turned on, the inductor L prevents the current from increasing. When the coil current increases to the opening current I on Before that, the electromagnetic force is not enough to overcome the movement resistance, and the valve core has not moved. 2) Valve core opening movement stage t2. When the coil current increases to I on After that, the valve core starts to move. The additional back electromotive force of the coil inductance causes the current to decrease, and the curve shows an inflection point B. 3) The stop phase after the valve core is in place. The valve core is in the maximum open position x m The current increases again, and a turning point C appears until the steady-state position U / R is reached. 4) Power-off delay stage t3. The coil inductance prevents the current from changing suddenly, and the valve core remains open. 5) Valve core closing movement stage t4. The coil inductance back electromotive force prevents the current from decreasing, and a turning point E appears. The EF segment shows an upward trend. After the valve is closed, the current quickly decays to zero and reaches point G.

[0110] Through the analysis of the switching characteristics, there is an obvious delay between the valve core feedback and the given voltage signal. Therefore, this embodiment further analyzes the cylinder movement by combining the phase plane trajectory. Assuming that the cylinder control mode is a constant speed system, the simplified schematic diagram is as follows: Figure 5 As shown. Figure 5 In the equation, δ is the control dead zone; τ is the equivalent switch lag time; G(S) is the transfer function of the controlled device. The entire motion control process is Figure 6 The horizontal axis is the control deviation e, which is defined as the difference between the setting r and the feedback displacement x; the vertical axis is the speed In the figure, the two straight lines l:e=-δ and m:e=δ are the controller switching lines. Due to the control lag τ, the effective switching lines are l′ and m′, which are expressed as:

[0111]

[0112] Define v0 as the design speed, positive level u +, negative level u - , zero level u0 are the three states of the controller output u. When v0>2δ / τ, u=u + , the cylinder moves to the right from point A on the phase plane; when it reaches the switch line l, u = u0; the actual valve core closing hysteresis causes the cylinder to maintain v0 and continue to move to the right within time τ, until it intersects with the effective switch line l' at point B, and the valve core is completely closed; at this time, the actual speed is 0, and the cylinder stops at point C. Since e>δ, u = u - , the cylinder moves to the left at a speed of -v0 on the phase plane and intersects the effective switch line m' at point E, and the cylinder stops at point F. Since e<-δ, u=u + , repeat the above process. A closed curve is drawn along the phase trajectory A→B→C→D→E→F→A, forming a semi-stable limit cycle to produce limit cycle oscillation. If v0<2δ / τ, the phase trajectory starting from A′ will stabilize at the equilibrium point along A′→B′→C′→D′.

[0113] In summary, if only the control accuracy δ is used as the switch line, the stability criterion of the DCV hydraulic position control process is:

[0114]

[0115] Since the control lag time τ is inherent in the control process, the control accuracy δ is inversely proportional to the cylinder speed v0. Therefore, the embodiment needs to consider how to ensure that the cylinder control process can improve the cylinder control accuracy under the condition of dynamic response (without reducing the movement speed).

[0116] Since the DCV can be switched to three states through two solenoids (a, b), it means that only three inputs can be generated for the discrete control signal of the cylinder. Based on the time optimal principle, the conventional Bang-Bang control system can be briefly described as:

[0117]

[0118] When |e(t)|≤δ, the Bang-Bang control system stops outputting until the error exceeds the control accuracy range again. At the same time, because of the time lag in the control, the minimum switching time of the control signal should fully consider the non-steady-state process of the valve core opening stage and the power-off valve core closing stage, and the minimum switching interval time of the control signal u is limited as follows:

[0119] T int >T min =t on +t off +t others (6)

[0120] Where, T intT is the time interval between the two DCV solenoids being energized; min is the minimum time interval allowed; t on is the opening response time of the electromagnetic reversing valve; t off is the closing response time of the electromagnetic reversing valve; t others It includes the controller scanning cycle, digital output module and intermediate relay response time, etc.

[0121] Conventional Bang-Bang control systems only use δ as a switching condition, which can easily cause "jittering" problems during position following. To solve this problem, this application introduces another switching condition: a dynamic switch line function. For a positioning control system, the target position x ref (t) is a piecewise constant, then its differential is zero. Let the dynamic error e(t) be the target position x ref (t) and the actual position x act (t), the dynamic deviation e(t) and the motion speed v(t) are as follows:

[0122]

[0123] The ideal cylinder positioning control goal is to move the cylinder to the target point, that is, when the dynamic deviation e(t) is less than a certain control accuracy range, the control signal switches to zero-level output u=u0, and the movement speed v(t) converges to 0 at the same time. In the actual cylinder movement, when DCV switches to zero-level output, the actual valve core will not close immediately. The phase plane motion trajectory S(t) is as follows Figure 7 As shown, the cylinder movement is divided into two stages: ① The cylinder slides at the initial speed, corresponding to the DCV power-off delay stage; ② The cylinder decelerates until it stops, corresponding to the valve core closing movement stage after the DCV power is off.

[0124] The movement distance of the cylinder from the DCV power failure to the complete stop of the cylinder movement is defined as the creeping distance δ crawl , as shown below:

[0125]

[0126] Where, t crawl v is the creeping time from power failure to complete stop of the oil cylinder; crawl (t) is the creeping speed of the cylinder after power failure.

[0127] Due to the complexity of the oil cylinder control process and the uncertainty of the external load, it is not easy to obtain the actual motion trajectory S(t) of the oil cylinder crawling in this embodiment. However, under the same working conditions and external load conditions, the trajectory shape is fixed, and the crawling distance δ crawl is also bounded, and 0≤v crawl(t)≤v0, v0 is the actual speed of the system in steady state. stop is the deviation value when power is off, that is, e(t) = e stop is the switch line function, e ss is the deviation value when the cylinder stops completely, then the creeping distance δ crawl can be rewritten as:

[0128] δ crawl =e ss -e stop (9)

[0129] The control goal of this embodiment is: when the DCV is powered off, the oil cylinder stops near the target position after crawling for a period of time. The crawling distance caused by time lag is the main factor affecting the final control accuracy. Therefore, it is necessary to iteratively learn and adaptively adjust the switch line function so that it gradually approaches the crawling distance. In essence, the iterative learning control strategy is a type of online optimization control strategy, which takes the error approaching zero during the control process as the optimization goal. This method adopts a simple P-type iterative learning control strategy, and the switch line iterative learning algorithm is:

[0130]

[0131] Where: k is the adaptive learning factor. The value of the adaptive learning factor k has an important influence on the performance of the controller. If the value of k is too low, the convergence speed of iterative learning and control error will slow down; if the value of k is too large, it will lead to a large steady-state fluctuation error in the control process, and even oscillation. There is no standardized learning method for the specific value of k. When the controller structure is determined, the value of k mainly depends on the performance of the controlled object and the actuator. Therefore, this embodiment uses repeated experiments to obtain a suitable range of values.

[0132] The control algorithm flow chart of this embodiment is as follows Figure 2 The controller uses the control dead zone δ as the start condition for tracking, and the switch line e stop As the end condition of tracking. Each tracking allows only one DCV state switch, and completes one iteration of the switch function learning. When the working condition is constant within a certain time range, the load is not disturbed or changes regularly, the crawling distance δ crawl The fluctuation is small. As the number of iterative learning increases, this embodiment can achieve zero error trajectory progressive tracking along the iteration axis in a limited time. Since the initial speed and load conditions of the rise and fall of the cylinder are different, this embodiment designs different switch line functions e(t) = -e for the rise and fall respectively. stop+ and e(t) = e stop-This method only needs to consider that the control deviation e(t) and the motion speed v(t) converge to 0 at the same time, without complex modeling of the switch line function, thus simplifying the solution of the problem. More importantly, an open-loop Bang-Bang control system can be turned into a closed-loop control system.

[0133] It is necessary to set a reasonable control dead zone δ according to the process control accuracy requirements, so as to avoid repeated adjustments due to too small control dead zone setting during oil cylinder positioning tracking, i.e., "chattering". At the same time, this embodiment adopts switch line iterative learning, which can achieve progressive tracking with control error approaching zero, and the static error of positioning control is small, which provides a certain buffer area for the oil cylinder position drift caused by internal leakage of hydraulic components after tracking is completed and exceeds the error range again, reduces the DCV action frequency, and reduces the damage to the oil cylinder or hydraulic valve station seal caused by transient oil medium impact caused by frequent opening / closing of DCV, thereby extending the service life of the equipment.

[0134] Since DCV can only adjust the medium flow rate by opening or closing the gap to achieve cylinder positioning, that is, the medium flow rate and speed cannot be adjusted during the control process, only rectangular waves can be used to verify the static response performance of the cylinder control process. Figure 8 a) is the reference roll gap setting and the actual roll gap value of the cylinder movement. The reference roll gap is a rectangular wave with a frequency of 0.1Hz and an amplitude of 2mm. b) is the static deviation value, which is defined as the difference between the roll gap setting and the actual value when the cylinder stops completely after the DCV is powered off. Figure 8 It can be seen that the static deviation becomes smaller and smaller with the switch line setting, and is in a convergence state, proving that the control algorithm and the switch line adaptive adjustment effect are obvious. c) is the cylinder movement speed. Since the system uses an asymmetric cylinder, the cylinder rising speed (about 1.5mm / s) and the descending speed (about 0.9mm / s) are different. d) is the DCV control output and valve core feedback. Figure 8 The lower left corner is an enlarged view. It is worth noting that during the first square wave tracking, since the switch line has not been adjusted, the cylinder exceeds the set accuracy range after rising, so it has another downward movement, that is, the "jitter" phenomenon. After 3 to 5 iterative learning, the static deviation converges quickly, so the DCV can achieve a higher control accuracy by switching only once.

[0135] In summary, the present application provides a cylinder control method based on a reversing valve, by calculating the difference between the real-time position of the cylinder before the cylinder is in a triggered state and a preset reference position as a first control deviation value; then the first control deviation value is compared with the first reference value and the second reference value respectively, and the cylinder trigger state is entered according to the comparison result, the reversing valve is powered, and the cylinder is controlled to rise or fall according to the power supply result of the reversing valve; wherein the absolute value of the first reference value is the same as the absolute value of the second reference value, and the sum of the first reference value and the second reference value is zero; then the difference between the real-time position of the cylinder and the preset reference position in the cylinder trigger state is calculated, recorded as a second control deviation value; then the second control deviation value is compared with the first cylinder switch line respectively, and the reversing valve is closed according to the comparison result to control the cylinder movement speed to zero; finally, the static deviation value when the cylinder movement speed is zero is obtained, and the second cylinder switch line is calculated based on the static deviation value, and the first cylinder switch line is replaced by the second cylinder switch line, so that the static deviation value when the actual movement speed of the cylinder is zero at the next moment is smaller than the current moment. It can be seen that this method can ensure that the static deviation value when the cylinder movement speed is zero is getting smaller and smaller by iteratively learning the cylinder switch line when the cylinder is completely finished, and replace the cylinder switch line at the previous moment with the iteratively learned cylinder switch line, thereby improving the accuracy of the cylinder positioning control system. In addition, this method only allows the reversing valve to switch once each time the cylinder tracking control is performed, thereby effectively reducing the switching frequency of the reversing valve, solving the "jitter" problem that occurs in the prior art, and reducing the instantaneous impact of the reversing valve on the valve control system due to the opening / closing of the valve, which is beneficial to extending the service life of the equipment. In addition, this method uses a simple and economical ordinary reversing valve to replace complex and expensive servo valves, proportional valves, high-speed switch valves, etc., which can not only realize the roller gap precision control of the continuous casting fan segment, but also effectively reduce the enterprise's initial project investment and later operation and maintenance costs while ensuring the process control accuracy and system stability, which has positive significance for the enterprise to reduce costs and increase efficiency. At the same time, the control algorithm of this method is simple and does not require complex modeling of the hydraulic system, thereby reducing the requirements for controller performance. It is particularly suitable for the fan-shaped segment roll gap control process and can be used in application environments where a PLC controls dozens of cylinders at the same time.

[0136] like Fig. 9 As shown, the present application also provides a cylinder control system based on a reversing valve, the system comprising:

[0137] A first control deviation module 910 is used to calculate the difference between the real-time position of the cylinder before the cylinder is in a triggered state and a preset reference position, which is recorded as a first control deviation value;

[0138] A first comparison module 920 is used to compare the first control deviation value with a first reference value and a second reference value respectively; wherein the absolute values ​​of the first reference value and the second reference value are the same, and the sum of the first reference value and the second reference value is zero;

[0139] The first oil cylinder control module 930 is used to enter the oil cylinder triggering state according to the comparison result of the first comparison module, supply power to the reversing valve, and control the oil cylinder to rise or fall according to the power supply result of the reversing valve;

[0140] A second control deviation module 940 is used to calculate the difference between the real-time position of the cylinder and the preset reference position in the cylinder trigger state, which is recorded as a second control deviation value;

[0141] A second comparison module 950 compares the second control deviation value with the first cylinder switch line respectively;

[0142] A second oil cylinder control module 960, used to close the reversing valve according to the comparison result of the second comparison module, and control the movement speed of the oil cylinder to zero;

[0143] The cylinder iteration control module 970 is used to obtain the static deviation value when the cylinder movement speed is zero, calculate the second cylinder switch line based on the static deviation value, and replace the first cylinder switch line with the second cylinder switch line so that the static deviation value when the actual movement speed of the cylinder is zero at the next moment is smaller than the current moment.

[0144] It can be seen that this embodiment performs iterative learning of the cylinder switch line when the cylinder is completely finished, and replaces the cylinder switch line of the previous moment with the iteratively learned cylinder switch line, so as to ensure that the static deviation value when the cylinder movement speed is zero is getting smaller and smaller, thereby improving the accuracy of the cylinder positioning control system. In addition, this embodiment only allows the reversing valve to switch once each time the cylinder tracking control is performed, thereby effectively reducing the switching frequency of the reversing valve, solving the "chattering" problem that occurs in the prior art, reducing the instantaneous impact of the reversing valve on the valve control system due to the opening / closing of the reversing valve, and is conducive to extending the service life of the equipment. In addition, this embodiment uses a simple and economical ordinary reversing valve to replace complex and expensive servo valves, proportional valves, high-speed switch valves, etc., which can not only realize the roller gap precision control of the continuous casting fan segment, but also effectively reduce the enterprise's initial project investment and later operation and maintenance costs while ensuring the process control accuracy and system stability, which has positive significance for the enterprise to reduce costs and increase efficiency. At the same time, the control algorithm of this embodiment is simple and does not require complex modeling of the hydraulic system, thereby reducing the requirements for controller performance. It is particularly suitable for the fan-shaped segment roll gap control process and can be applied to the application environment where a PLC controls dozens of cylinders at the same time.

[0145] In an exemplary embodiment, if the first reference value is a negative value and the second reference value is a positive value, the first cylinder control module 930 enters the cylinder trigger state according to the comparison result of the first comparison module, supplies power to the reversing valve, and controls the cylinder to rise or fall according to the power supply result of the reversing valve. The process includes: if the first control deviation value is less than the first reference value, the cylinder enters the positive trigger state, supplies power to the reversing valve in a positive direction, and controls the cylinder to rise; if the first control deviation value is greater than the second reference value, the cylinder enters the negative trigger state, supplies power to the reversing valve in a negative direction, and controls the cylinder to descend; if the first control deviation value is greater than or equal to the first reference value and less than or equal to the second control deviation value, the cylinder trigger state is not entered, the reversing valve is de-energized, and the difference between the real-time position of the cylinder and the preset reference position before the cylinder trigger state is recalculated.

[0146] In an exemplary embodiment, the process in which the cylinder iteration control module 970 obtains the static deviation value when the cylinder movement speed is zero and calculates the second cylinder switch line based on the static deviation value includes: obtaining the first cylinder switch line and the static deviation value According to the first oil cylinder switch line and the static deviation value Perform iterative learning to obtain the second cylinder switch line have: Where i is the number of cylinder control times, i = 0, 1, 2, 3 ... n; when i = 0, it means the first cylinder control, at this time the first cylinder switch line is the preset oil cylinder switch line in the initial state; k is the adaptive learning factor. As an example, in this embodiment, the first oil cylinder switch line Indicates the cylinder switch line when the i-th cylinder is controlled, the second cylinder switch line It represents the cylinder switch line after iterative learning based on the cylinder switch line during the i-th cylinder control. For example, when i=0, it means the first or first cylinder control. At this time, the first cylinder switch line Indicates the preset oil cylinder switch line in the initial state. The preset oil cylinder switch line in the initial state can be set according to actual conditions, and this embodiment does not impose a specific numerical limit.

[0147] According to the above records, in an exemplary embodiment, the process of the cylinder iteration control module obtaining the static deviation value when the cylinder movement speed is zero includes: obtaining the movement distance of the cylinder from the time when the reversing valve is powered off to the time when the cylinder movement stops completely, recorded as the creeping distance δ crawl ,have: Get the deviation value when the reversing valve is powered off, recorded as e stop; According to the crawling distance δ crawl and the deviation value e when the reversing valve is powered off stop Calculate the static deviation value e when the cylinder movement speed is zero ss , there are: e ss =δ crawl +e stop Where, t crawl v is the creeping time from when the reversing valve is powered off to when the cylinder stops moving completely, crawl (t) is the creeping speed of the cylinder after the reversing valve is powered off.

[0148] In an exemplary embodiment, the dynamic equation of the reversing valve is as follows: In the formula, F v is the electromagnetic attraction force after the solenoid is powered on; m v is the mass of the moving parts; C is the viscous damping coefficient; k s is the stiffness coefficient of the pull-back spring; x v is the valve core displacement; is the first-order derivative of the valve core displacement; is the second-order derivative of the valve core displacement. Specifically, the reversing valve comprises a solenoid, a valve core and a pull-back spring, and the solenoid generates an electromagnetic force after being powered on, and after interacting with the pull-back spring, the valve core is opened or closed.

[0149] In another exemplary embodiment, the present application also provides a cylinder control system based on a reversing valve, which is used to perform the following steps:

[0150] S101, determine whether the control deviation e(t) is less than the control dead zone -δ. If the control deviation e(t) is less than the control dead zone -δ, that is, e(t)<-δ, then proceed to S201; if the control deviation e(t) is greater than the control dead zone -δ, then determine whether the control deviation e(t) is greater than the control dead zone δ. If the control deviation e(t) is greater than the control dead zone δ, that is, e(t)>δ, then proceed to S301; if the control deviation e(t) is within the control dead zone, that is, |e(t)|≤δ, then DCV power is lost (u(t)=u0), and the judgment of S101 is repeated to continue to determine whether the control deviation e(t) is less than the control dead zone -δ. In this embodiment, the control deviation e(t) in step S101 can also be the first control deviation value in other embodiments, the control dead zone -δ can also be the first reference value in other embodiments, and the control dead zone δ can also be the second reference value in other embodiments.

[0151] S201, turn on DCV to get power in the forward direction, u(t) = u + , the oil cylinder rises and enters S202;

[0152] S202, determine whether the control deviation e(t) is greater than the oil cylinder rising switch line -e stop+ , that is, e(t)<-e stop+ No, keep DCV energized in the forward direction; yes, go to S203; wherein, in this embodiment, the control deviation e(t) in step S202 may also be the second control deviation value in other embodiments.

[0153] S203, DCV power failure, u(t)=u0, transfer to S204;

[0154] S204, determine whether the actual movement speed v(t) of the oil cylinder is 0, v(t=0, no, continue to wait; yes, go to S205;

[0155] S205, record the static deviation value e at this time ss , and perform a switch line e stop+ The iterative learning of the switch line is as follows:

[0156]

[0157] Wherein, k is the adaptive learning factor. In this embodiment, the switch line in step S205 It can also be the first oil cylinder switch line in other embodiments, after iteration It may also be the second oil cylinder switch line in other embodiments.

[0158] S301, turn on DCV negative power, u(t) = u - , the oil cylinder descends and enters S302;

[0159] S302: Determine whether the control deviation e(t) is less than the cylinder lowering switch line e stop- , that is, e(t)>e stop- No, keep DCV negatively energized; yes, go to S303; wherein, in this embodiment, the control deviation e(t) in step S302 may also be the second control deviation value in other embodiments.

[0160] S303, DCV power failure, u(t)=u0, go to S304;

[0161] S304, determine whether the actual movement speed v(t) of the oil cylinder is 0, v(t=0, no, continue to wait; yes, go to S305;

[0162] S305, record the static deviation value e at this time ss , and perform a switch line e stop-The iterative learning of the switch line is as follows:

[0163]

[0164] Wherein, k is the adaptive learning factor. In this embodiment, the switch line in step S205 It can also be the first oil cylinder switch line in other embodiments, after iteration It may also be the second oil cylinder switch line in other embodiments.

[0165] Specifically, since the DCV is the core control component in the entire cylinder control process, the opening and closing time of the DCV has an important influence on the dynamic and static characteristics of the valve, and directly determines the stability and accuracy of the cylinder control process. Therefore, this embodiment can analyze the switching characteristics of the DCV. The basic structure of the reversing valve DCV in this embodiment is as follows Figure 3 As shown, Figure 3 It is the basic structure of a typical solenoid-type three-position four-way electromagnetic reversing valve, which consists of a housing 1, two solenoids 2, a valve core 3 and two pull-back springs 4. The valve core is opened or closed by the interaction between the electromagnetic force generated by the solenoid after power is turned on and the pull-back spring, so that the DCV is energized or de-energized. The simple dynamic equation of the DCV is as follows:

[0166]

[0167] In the formula, F v is the electromagnetic attraction force after the solenoid is powered on; m v is the mass of the moving parts; C is the viscous damping coefficient; k s is the stiffness coefficient of the pull-back spring; x v is the valve core displacement; is the first-order derivative of the valve core displacement; is the second-order derivative of the valve core displacement.

[0168] Among them, the electromagnet voltage equation is as follows:

[0169]

[0170] Where U is the coil terminal voltage; R is the coil internal resistance; L is the coil inductance; i is the coil current.

[0171] The switching dynamic process curve of DCV under rectangular wave excitation is as follows Figure 4 As shown in the figure, the electromagnet's attraction and release process is divided into five working stages, corresponding to the three movement processes of the valve core: 1) Electrical delay stage t1. When the power is turned on, the inductor L prevents the current from increasing. When the coil current increases to the opening current I onBefore that, the electromagnetic force is not enough to overcome the movement resistance, and the valve core has not moved. 2) Valve core opening movement stage t2. When the coil current increases to I on After that, the valve core starts to move. The additional back electromotive force of the coil inductance causes the current to decrease, and the curve shows an inflection point B. 3) The stop phase after the valve core is in place. The valve core is in the maximum open position x m The current increases again, and a turning point C appears until the steady-state position U / R is reached. 4) Power-off delay stage t3. The coil inductance prevents the current from changing suddenly, and the valve core remains open. 5) Valve core closing movement stage t4. The coil inductance back electromotive force prevents the current from decreasing, and a turning point E appears. The EF segment shows an upward trend. After the valve is closed, the current quickly decays to zero and reaches point G.

[0172] Through the analysis of the switching characteristics, there is an obvious delay between the valve core feedback and the given voltage signal. Therefore, this embodiment further analyzes the cylinder movement by combining the phase plane trajectory. Assuming that the cylinder control mode is a constant speed system, the simplified schematic diagram is as follows: Figure 5 As shown. Figure 5 In the equation, δ is the control dead zone; τ is the equivalent switch lag time; G(S) is the transfer function of the controlled device. The entire motion control process is Figure 6 The horizontal axis is the control deviation e, which is defined as the difference between the setting r and the feedback displacement x; the vertical axis is the speed In the figure, the two straight lines l:e=-δ and m:e=δ are the controller switching lines. Due to the control lag τ, the effective switching lines are l′ and m′, which are expressed as:

[0173]

[0174] Define v0 as the design speed, positive level u + , negative level u - , zero level u0 are the three states of the controller output u. When v0>2δ / τ, u=u + , the cylinder moves to the right from point A on the phase plane; when it reaches the switch line l, u = u0; the actual valve core closing hysteresis causes the cylinder to maintain v0 and continue to move to the right within time τ, until it intersects with the effective switch line l' at point B, and the valve core is completely closed; at this time, the actual speed is 0, and the cylinder stops at point C. Since e>δ, u = u - , the cylinder moves to the left at a speed of -v0 on the phase plane and intersects the effective switch line m' at point E, and the cylinder stops at point F. Since e<-δ, u=u + , repeat the above process. A closed curve is drawn along the phase trajectory A→B→C→D→E→F→A, forming a semi-stable limit cycle to produce limit cycle oscillation. If v0<2δ / τ, the phase trajectory starting from A′ will stabilize at the equilibrium point along A′→B′→C′→D′.

[0175] In summary, if only the control accuracy δ is used as the switch line, the stability criterion of the DCV hydraulic position control process is:

[0176]

[0177] Since the control lag time τ is inherent in the control process, the control accuracy δ is inversely proportional to the cylinder speed v0. Therefore, the embodiment needs to consider how to ensure that the cylinder control process can improve the cylinder control accuracy under the condition of dynamic response (without reducing the movement speed).

[0178] Since the DCV can be switched to three states through two solenoids (a, b), it means that only three inputs can be generated for the discrete control signal of the cylinder. Based on the time optimal principle, the conventional Bang-Bang control system can be briefly described as:

[0179]

[0180] When |e(t)|≤δ, the Bang-Bang control system stops outputting until the error exceeds the control accuracy range again. At the same time, because of the time lag in the control, the minimum switching time of the control signal should fully consider the non-steady-state process of the valve core opening stage and the power-off valve core closing stage, and the minimum switching interval time of the control signal u is limited as follows:

[0181] T int >T min =t on +t off +t others (6)

[0182] Where, T int T is the time interval between the two DCV solenoids being energized; min is the minimum time interval allowed; t on is the opening response time of the electromagnetic reversing valve; t off is the closing response time of the electromagnetic reversing valve; t others It includes the controller scanning cycle, digital output module and intermediate relay response time, etc.

[0183] Conventional Bang-Bang control systems only use δ as a switching condition, which can easily cause "jittering" problems during position following. To solve this problem, this application introduces another switching condition: a dynamic switch line function. For a positioning control system, the target position x ref (t) is a piecewise constant, then its differential is zero. Let the dynamic error e(t) be the target position x ref (t) and the actual position x act (t), the dynamic deviation e(t) and the motion speed v(t) are as follows:

[0184]

[0185] The ideal cylinder positioning control goal is to move the cylinder to the target point, that is, when the dynamic deviation e(t) is less than a certain control accuracy range, the control signal switches to zero-level output u=u0, and the movement speed v(t) converges to 0 at the same time. In the actual cylinder movement, when DCV switches to zero-level output, the actual valve core will not close immediately. The phase plane motion trajectory S(t) is as follows Figure 7 As shown, the cylinder movement is divided into two stages: ① The cylinder slides at the initial speed, corresponding to the DCV power-off delay stage; ② The cylinder decelerates until it stops, corresponding to the valve core closing movement stage after the DCV power is off.

[0186] The movement distance of the cylinder from the DCV power failure to the complete stop of the cylinder movement is defined as the creeping distance δ crawl , as shown below:

[0187]

[0188] Where, t crawl v is the creeping time from power failure to complete stop of the oil cylinder; crawl (t) is the creeping speed of the cylinder after power failure.

[0189] Due to the complexity of the oil cylinder control process and the uncertainty of the external load, it is not easy to obtain the actual motion trajectory S(t) of the oil cylinder crawling in this embodiment. However, under the same working conditions and external load conditions, the trajectory shape is fixed, and the crawling distance δ crawl is also bounded, and 0≤v crawl (t)≤v0, v0 is the actual speed of the system in steady state. stop is the deviation value when power is off, that is, e(t) = e stop is the switch line function, e ss is the deviation value when the cylinder stops completely, then the creeping distance δ crawl can be rewritten as:

[0190] δ crawl =e ss -e stop (9)

[0191] The control goal of this embodiment is: when the DCV is powered off, the oil cylinder stops near the target position after crawling for a period of time. The crawling distance caused by time lag is the main factor affecting the final control accuracy. Therefore, it is necessary to iteratively learn and adaptively adjust the switch line function so that it gradually approaches the crawling distance. In essence, the iterative learning control strategy is a type of online optimization control strategy, which takes the error approaching zero during the control process as the optimization goal. This system adopts a simple P-type iterative learning control strategy, and the switch line iterative learning algorithm is:

[0192]

[0193] Where: k is the adaptive learning factor. The value of the adaptive learning factor k has an important influence on the performance of the controller. If the value of k is too low, the convergence speed of iterative learning and control error will slow down; if the value of k is too large, it will lead to a large steady-state fluctuation error in the control process, and even oscillation. There is no standardized learning method for the specific value of k. When the controller structure is determined, the value of k mainly depends on the performance of the controlled object and the actuator. Therefore, this embodiment uses repeated experiments to obtain a suitable range of values.

[0194] The control algorithm flow chart of this embodiment is as follows Figure 2 The controller uses the control dead zone δ as the start condition for tracking, and the switch line e stop As the end condition of tracking. Each tracking allows only one DCV state switch, and completes one iteration of the switch function learning. When the working condition is constant within a certain time range, the load is not disturbed or changes regularly, the crawling distance δ crawl The fluctuation is small. As the number of iterative learning increases, this embodiment can achieve zero error trajectory progressive tracking along the iteration axis in a limited time. Since the initial speed and load conditions of the rise and fall of the cylinder are different, this embodiment designs different switch line functions e(t) = -e for the rise and fall respectively. stop+ and e(t) = e stop- This method only needs to consider that the control deviation e(t) and the motion speed v(t) converge to 0 at the same time, without complex modeling of the switch line function, thus simplifying the solution of the problem. More importantly, an open-loop Bang-Bang control system can be turned into a closed-loop control system.

[0195] It is necessary to set a reasonable control dead zone δ according to the process control accuracy requirements, so as to avoid repeated adjustments due to too small control dead zone setting during oil cylinder positioning tracking, i.e., "chattering". At the same time, this embodiment adopts switch line iterative learning, which can achieve progressive tracking with control error approaching zero, and the static error of positioning control is small, which provides a certain buffer area for the oil cylinder position drift caused by internal leakage of hydraulic components after tracking is completed and exceeds the error range again, reduces the DCV action frequency, and reduces the damage to the oil cylinder or hydraulic valve station seal caused by transient oil medium impact caused by frequent opening / closing of DCV, thereby extending the service life of the equipment.

[0196] Since DCV can only adjust the medium flow rate by opening or closing the gap to achieve cylinder positioning, that is, the medium flow rate and speed cannot be adjusted during the control process, only rectangular waves can be used to verify the static response performance of the cylinder control process. Figure 8 a) is the reference roll gap setting and the actual roll gap value of the cylinder movement. The reference roll gap is a rectangular wave with a frequency of 0.1Hz and an amplitude of 2mm. b) is the static deviation value, which is defined as the difference between the roll gap setting and the actual value when the cylinder stops completely after the DCV is powered off. Figure 8 It can be seen that the static deviation becomes smaller and smaller with the switch line setting, and is in a convergence state, proving that the control algorithm and the switch line adaptive adjustment effect are obvious. c) is the cylinder movement speed. Since the system uses an asymmetric cylinder, the cylinder rising speed (about 1.5mm / s) and the descending speed (about 0.9mm / s) are different. d) is the DCV control output and valve core feedback. Figure 8 The lower left corner is an enlarged view. It is worth noting that during the first square wave tracking, since the switch line has not been adjusted, the cylinder exceeds the set accuracy range after rising, so it has another downward movement, that is, the "jitter" phenomenon. After 3 to 5 iterative learning, the static deviation converges quickly, so the DCV can achieve a higher control accuracy by switching only once.

[0197] It should be noted that the reversing valve-based cylinder control system provided in the above embodiment and the reversing valve-based cylinder control method provided in the above embodiment belong to the same concept, wherein the specific manner in which each module and unit performs the operation has been described in detail in the method embodiment, and will not be repeated here. In actual application, the reversing valve-based cylinder control system provided in the above embodiment can distribute the above functions to different functional modules as needed, that is, divide the internal structure of the system into different functional modules to complete all or part of the functions described above, and this is not limited here.

[0198] In summary, the present application provides a cylinder control system based on a reversing valve, which calculates the difference between the real-time position of the cylinder before the cylinder is in a triggered state and a preset reference position as a first control deviation value; then the first control deviation value is compared with the first reference value and the second reference value respectively, and the cylinder trigger state is entered according to the comparison result, the reversing valve is powered, and the cylinder is controlled to rise or fall according to the power supply result of the reversing valve; wherein the absolute value of the first reference value is the same as the absolute value of the second reference value, and the sum of the first reference value and the second reference value is zero; then the difference between the real-time position of the cylinder and the preset reference position in the cylinder trigger state is calculated, recorded as a second control deviation value; then the second control deviation value is compared with the first cylinder switch line respectively, and the reversing valve is closed according to the comparison result to control the cylinder movement speed to zero; finally, the static deviation value when the cylinder movement speed is zero is obtained, and the second cylinder switch line is calculated based on the static deviation value, and the first cylinder switch line is replaced by the second cylinder switch line, so that the static deviation value when the actual movement speed of the cylinder is zero at the next moment is smaller than the current moment. It can be seen that this system can ensure that the static deviation value when the cylinder movement speed is zero is getting smaller and smaller by iteratively learning the cylinder switch line when the cylinder is completely finished, and replace the cylinder switch line at the previous moment with the iteratively learned cylinder switch line, so as to improve the accuracy of the cylinder positioning control system. In addition, this system only allows the reversing valve to switch once each time the cylinder tracking control is performed, thereby effectively reducing the switching frequency of the reversing valve, solving the "jittering" problem that occurs in the prior art, and reducing the instantaneous impact of the reversing valve opening / closing on the valve control system, which is conducive to extending the service life of the equipment. In addition, this system uses simple and economical ordinary reversing valves to replace complex and expensive servo valves, proportional valves, high-speed switch valves, etc., which can not only realize the roller gap precision control of the continuous casting fan segment, but also effectively reduce the enterprise's initial project investment and later operation and maintenance costs while ensuring the process control accuracy and system stability, which has positive significance for the enterprise to reduce costs and increase efficiency. At the same time, the control algorithm of this system is simple and does not require complex modeling of the hydraulic system, thereby reducing the requirements for controller performance. It is particularly suitable for the fan-shaped segment roll gap control process and can be used in application environments where a PLC controls dozens of cylinders at the same time.

[0199] like Fig.10As shown, the present application also provides a device for implementing the oil cylinder control method based on the reversing valve as described in any of the above, the device includes an outer arc frame and an inner arc frame, and a positioning oil cylinder is arranged on the inner arc frame, and the positioning oil cylinder is used to close the loop and adjust the roll gap value between the outer arc frame and the inner arc frame to control the thickness of the ingot. Specifically, the positioning oil cylinder includes a position sensor and a reversing valve hydraulic valve station; the reversing valve hydraulic valve station includes an electromagnetic reversing valve, a hydraulic lock, a throttling damping hole and a relief valve, the oil outlet of the electromagnetic reversing valve is connected to the cavity of the oil cylinder through the hydraulic lock and the throttling damping hole, the position sensor is installed on the piston rod of the oil cylinder, and is used to measure the real-time output displacement of the oil cylinder; the relief valve is used to keep the oil cylinder pressure stable and to perform pressure protection on the oil cylinder.

[0200] According to the above records, in an exemplary embodiment, the structure of the oil cylinder control device based on the reversing valve is as follows: Fig.10 As shown, the device consists of an outer arc frame ① and an inner arc frame ②. The outer arc frame ① is fixed on the fan-shaped segment equipment, and the inner arc frame ② is connected to the outer arc frame ① by 4 sets of positioning cylinders ④. Each set of positioning cylinders ④ is equipped with a separate position sensor ⑤ and a DCV hydraulic valve station ③, which are used for closed-loop adjustment of the roll gap value between the outer arc frame ① and the inner arc frame ②, thereby controlling the thickness of the casting. Fig.11 The figure shows a 1 / 4 schematic diagram of a sector position control hydraulic system using DCV, which consists of an electromagnetic reversing valve 1, two hydraulic locks 2, a first throttling damping hole 3.1, a second throttling damping hole 3.2, a first overflow valve 4.1 and a second overflow valve 4.2. Among them, the oil outlet A and the oil outlet B of the electromagnetic reversing valve 1 are connected to the A chamber and the B chamber of the oil cylinder 5 through two hydraulic locks 2, the first throttling damping hole 3.1 and the second throttling damping hole 3.2 respectively; the first overflow valve 4.1 and the second overflow valve 4.2 are used to maintain the stability of the oil cylinder pressure and high pressure protection; the displacement sensor 6 is installed on the piston rod of the oil cylinder 5 to measure the real-time output displacement of the oil cylinder.

[0201] It can be seen that the device can ensure that the static deviation value when the cylinder movement speed is zero is getting smaller and smaller by iteratively learning the cylinder switch line when the cylinder is completely finished, and replace the cylinder switch line at the previous moment with the iteratively learned cylinder switch line, thereby improving the accuracy of the cylinder positioning control system. In addition, the device only allows the reversing valve to switch once each time the cylinder tracking control is performed, thereby effectively reducing the switching frequency of the reversing valve, solving the "jitter" problem that occurs in the prior art, and reducing the instantaneous impact of the reversing valve on the valve control system due to the opening / closing of the valve, which is conducive to extending the service life of the equipment. In addition, the device uses a simple and economical ordinary reversing valve to replace complex and expensive servo valves, proportional valves, high-speed switch valves, etc., which can not only realize the roller gap precision control of the continuous casting fan segment, but also effectively reduce the enterprise's initial project investment and later operation and maintenance costs while ensuring the process control accuracy and system stability, which has positive significance for the enterprise to reduce costs and increase efficiency. At the same time, the control algorithm of this device is simple, and there is no need to carry out complex modeling of the hydraulic system, thereby reducing the requirements for the performance of the controller. It is particularly suitable for the fan-shaped segment roll gap control process and can be used in the application environment where a PLC controls dozens of cylinders at the same time. This device uses a common reversing valve as a control element, an asymmetric cylinder as an actuator, and a throttling damping hole as a speed regulating element. The hydraulic circuit is simple and reliable.

[0202] It should be noted that the reversing valve-based cylinder control device provided in the above embodiment is used to implement the reversing valve-based cylinder control method provided in the above embodiment, wherein the functions of each component refer to the above method embodiment and will not be repeated here. In actual application, the reversing valve-based cylinder control device provided in the above embodiment can divide the internal structure of the above device into different functional modules as needed to complete all or part of the functions described above, and this is not limited here. Therefore, the present application effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0203] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

[0204] The structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of this application, so they have no substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects and purposes that can be achieved by this application, should still fall within the scope of the technical content disclosed in this application. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of this application. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of this application without substantial change in the technical content.

[0205] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present application, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present application, the first control deviation value may also be referred to as the second control deviation value, and similarly, the second control deviation value may also be referred to as the first control deviation value.

Claims

1. A cylinder control method based on a reversing valve, characterized in that: The method comprises the following steps: Calculate the difference between the real-time position of the cylinder before the cylinder is in the triggered state and the preset reference position, and record it as the first control deviation value; The first control deviation value is compared with a first reference value and a second reference value respectively, and according to the comparison result, the oil cylinder trigger state is entered, the reversing valve is powered, and the oil cylinder is controlled to rise or fall according to the power supply result of the reversing valve; wherein the absolute values ​​of the first reference value and the second reference value are the same, and the sum of the first reference value and the second reference value is zero; Calculate the difference between the real-time position of the cylinder and the preset reference position in the cylinder trigger state, and record it as the second control deviation value; Compare the second control deviation value with the first cylinder switch line respectively, and close the reversing valve according to the comparison result to control the cylinder movement speed to zero; Obtaining a static deviation value when the cylinder movement speed is zero, calculating a second cylinder switch line based on the static deviation value, and replacing the first cylinder switch line with the second cylinder switch line, so that the static deviation value when the actual movement speed of the cylinder is zero at the next moment is smaller than that at the current moment; The process of obtaining the static deviation value when the cylinder movement speed is zero and calculating the second cylinder switch line based on the static deviation value includes: Get the movement distance of the cylinder from the time the reversing valve is powered off to the time the cylinder movement stops completely, recorded as the creeping distance δ crawl ,have: Get the deviation value when the reversing valve is powered off, recorded as e stop ; According to the crawling distance δ crawl and the deviation value e when the reversing valve is powered off stop Calculate the static deviation value e when the cylinder movement speed is zero ss , there are: e ss =δ crawl +e stop ; In the formula, t crawl v is the creeping time from when the reversing valve is powered off to when the cylinder stops moving completely, crawl (t) is the creeping speed of the oil cylinder after the reversing valve is powered off; where, Where e(t) represents the dynamic deviation, x act (t) represents the target position, x ref (t) represents the actual position, v(t) represents the movement speed; Indicates the target position x act The differential result of (t); And, get the first cylinder switch line and static deviation According to the first oil cylinder switch line and the static deviation value Perform iterative learning to obtain the second cylinder switch line have: In the formula, i is the number of cylinder control times, i = 0, 1, 2, 3 ... n; among them, the first cylinder switch line Indicates the cylinder switch line when the i-th cylinder is controlled, the second cylinder switch line It represents the cylinder switch line after iterative learning based on the cylinder switch line during the i-th cylinder control; when i=0, it means the first cylinder control, at this time the first cylinder switch line is the preset cylinder switch line in the initial state; k is the adaptive learning factor.

2. The oil cylinder control method based on the reversing valve according to claim 1 is characterized in that: If the first reference value is a negative value and the second reference value is a positive value, the first control deviation value is compared with the first reference value and the second reference value respectively, and according to the comparison result, the oil cylinder trigger state is entered, the reversing valve is powered, and the process of controlling the oil cylinder to rise or fall according to the power supply result of the reversing valve includes: Comparing the first control deviation value with a first reference value and a second reference value respectively; If the first control deviation value is less than the first reference value, the oil cylinder enters a positive trigger state, the reversing valve is positively powered, and the oil cylinder is controlled to rise; If the first control deviation value is greater than the second reference value, the oil cylinder enters a negative trigger state, the reversing valve is negatively powered, and the oil cylinder is controlled to descend; If the first control deviation value is greater than or equal to the first reference value and less than or equal to the second control deviation value, the cylinder trigger state is not entered, the reversing valve is de-energized, and the difference between the real-time position of the cylinder before the cylinder trigger state and the preset reference position is recalculated.

3. The oil cylinder control method based on the reversing valve according to claim 1 is characterized in that: The dynamic equation of the reversing valve is as follows: In the formula, F v is the electromagnetic attraction force after the solenoid is powered on; m v is the mass of the moving parts; C is the viscous damping coefficient; k s is the stiffness coefficient of the pull-back spring; x v is the valve core displacement; is the first-order derivative of the valve core displacement; is the second-order derivative of the valve core displacement.

4. The oil cylinder control method based on a reversing valve according to claim 1 or 3, characterized in that: The reversing valve comprises a solenoid, a valve core and a pull-back spring. The solenoid generates electromagnetic force after being powered on, and after interacting with the pull-back spring, the valve core is opened or closed.

5. A cylinder control system based on a reversing valve, characterized in that: The system comprises: A first control deviation module is used to calculate the difference between the real-time position of the cylinder before the cylinder is in a triggered state and a preset reference position, which is recorded as a first control deviation value; a first comparison module, configured to compare the first control deviation value with a first reference value and a second reference value respectively; wherein the absolute values ​​of the first reference value and the second reference value are the same, and the sum of the first reference value and the second reference value is zero; A first oil cylinder control module, used for entering an oil cylinder triggering state according to a comparison result of the first comparison module, supplying power to the reversing valve, and controlling the oil cylinder to rise or fall according to a power supply result of the reversing valve; A second control deviation module is used to calculate the difference between the real-time position of the cylinder and the preset reference position in the cylinder trigger state, which is recorded as a second control deviation value; A second comparison module compares the second control deviation value with the first cylinder switch line respectively; A second oil cylinder control module, used for closing the reversing valve according to the comparison result of the second comparison module, and controlling the movement speed of the oil cylinder to zero; The oil cylinder iteration control module is used to obtain the static deviation value when the oil cylinder movement speed is zero, calculate the second oil cylinder switch line based on the static deviation value, and replace the first oil cylinder switch line with the second oil cylinder switch line, so that the static deviation value when the actual movement speed of the oil cylinder is zero at the next moment is smaller than the current moment; The process in which the oil cylinder iteration control module obtains the static deviation value when the oil cylinder movement speed is zero and calculates the second oil cylinder switch line based on the static deviation value includes: Get the movement distance of the cylinder from the time the reversing valve is powered off to the time the cylinder movement stops completely, recorded as the creeping distance δ crawl ,have: Get the deviation value when the reversing valve is powered off, recorded as e stop ; According to the crawling distance δ crawl and the deviation value e when the reversing valve is powered off stop Calculate the static deviation value e when the cylinder movement speed is zero ss , there are: e ss =δ crawl +e stop ; In the formula, t crawl v is the creeping time from when the reversing valve is powered off to when the cylinder stops moving completely, crawl (t) is the creeping speed of the oil cylinder after the reversing valve is powered off; where, Where e(t) represents the dynamic deviation, x act (t) represents the target position, x ref (t) represents the actual position, v(t) represents the movement speed; Indicates the target position x act The differential result of (t); And, get the first cylinder switch line and static deviation According to the first oil cylinder switch line and the static deviation value Perform iterative learning to obtain the second cylinder switch line have: In the formula, i is the number of cylinder control times, i = 0, 1, 2, 3 ... n; among them, the first cylinder switch line Indicates the cylinder switch line when the i-th cylinder is controlled, the second cylinder switch line It represents the cylinder switch line after iterative learning based on the cylinder switch line during the i-th cylinder control; when i=0, it means the first cylinder control, at this time the first cylinder switch line is the preset cylinder switch line in the initial state; k is the adaptive learning factor.

6. The oil cylinder control system based on the reversing valve according to claim 5 is characterized in that: If the first reference value is a negative value and the second reference value is a positive value, the first cylinder control module enters the cylinder trigger state according to the comparison result of the first comparison module, supplies power to the reversing valve, and controls the cylinder to rise or fall according to the power supply result of the reversing valve. The process includes: If the first control deviation value is less than the first reference value, the oil cylinder enters a positive trigger state, the reversing valve is positively powered, and the oil cylinder is controlled to rise; If the first control deviation value is greater than the second reference value, the oil cylinder enters a negative trigger state, the reversing valve is negatively powered, and the oil cylinder is controlled to descend; If the first control deviation value is greater than or equal to the first reference value and less than or equal to the second control deviation value, the cylinder trigger state is not entered, the reversing valve is de-energized, and the difference between the real-time position of the cylinder before the cylinder trigger state and the preset reference position is recalculated.

7. A device for implementing the oil cylinder control method based on a reversing valve as claimed in any one of claims 1 to 4, characterized in that: The device comprises an outer arc frame and an inner arc frame. A positioning cylinder is arranged on the inner arc frame. The positioning cylinder is used for closed-loop adjustment of the roll gap value between the outer arc frame and the inner arc frame to control the thickness of the ingot.

8. The oil cylinder control device based on the reversing valve according to claim 7, characterized in that: The positioning cylinder includes a position sensor and a reversing valve hydraulic valve station; the reversing valve hydraulic valve station includes an electromagnetic reversing valve, a hydraulic lock, a throttling damping hole and a relief valve. The oil outlet of the electromagnetic reversing valve is connected to the cavity of the cylinder through the hydraulic lock and the throttling damping hole. The position sensor is installed on the piston rod of the cylinder to measure the real-time output displacement of the cylinder; the relief valve is used to maintain the stability of the cylinder pressure and provide pressure protection for the cylinder.

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