Position closed-loop control system and method of hydraulic system

Abstract

The invention discloses a position closed-loop control system and method of a hydraulic system, and belongs to the technical field of tunnel rock drilling hydraulic mechanical arm control, and the system comprises a linear displacement sensor which is used for obtaining the current position of a piston rod of a hydraulic cylinder; the programmable controller is used for adjusting the PID output value according to a preset PID output range and determining a control signal according to the adjusted PID output value; the proportional amplifier is connected with the programmable controller and is used for converting the analog quantity in the control signal into an electric signal; the proportional direction valve is connected with the proportional amplifier and used for determining the valve opening degree according to the electric signal; wherein the piston rod of the hydraulic cylinder controls the moving speed according to the opening degree of the valve, and the programmable controller is further used for generating a valve closing instruction when the current position coincides with the target position. The moving speed of the piston rod can be controlled by controlling the PID output value range, and excessive abrasion of the tunnel rock drilling mechanical arm is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel drilling hydraulic mechanical arm control, and in particular to a position closed-loop control system and method for a hydraulic system. Background Art

[0002] Tunnel drilling robot, as a tunnel blasting drilling equipment, is an important tunnel engineering equipment. It usually adopts a structure in which a drilling rig drives 2-3 hydraulic mechanical arms. The reversing valve of the hydraulic cylinder or hydraulic motor that drives the mechanical arm usually adopts a proportional directional valve. This is because the proportional directional valve can continuously adjust the valve core position according to the input electrical signal. By controlling the input electrical signal, the flow and direction of the valve can be accurately controlled.

[0003] PID (Proportional-Integral-Derivative Controller) control technology boasts high precision, fast response, strong adaptability, and excellent stability, making it widely used in industrial automation. As one of the three pillars of industrial automation, the PLC (Programmable Logic Controller) not only supports the PID control algorithm but also features PID parameter auto-tuning, automatically calculating optimal PID parameter values. It is easy to program and use. However, when using PLC PID for closed-loop position control of a hydraulic cylinder, before reaching the target position, the PLC PID controls the proportional directional valve to its maximum set value, approaching the target at maximum speed. As it approaches the target position, the valve spool oscillates in both the forward and reverse directions around its center position until it reaches the target position and the valve closes. However, excessive piston rod speed inevitably causes vibration in the robotic arm. High vibration frequencies can cause wear on mechanical components, increase operational difficulty, reduce drilling efficiency, and increase maintenance costs, while also posing safety risks.

[0004] Therefore, in the process of closed-loop position control of the hydraulic cylinder in the prior art, there is a problem of excessive wear of the tunnel drilling robot arm due to the inability to control the moving speed of the piston rod. Summary of the Invention

[0005] In view of this, it is necessary to provide a position closed-loop control system and method for a hydraulic system to solve the problem of excessive wear of the tunnel drilling robot arm due to the inability to control the moving speed of the piston rod during the position closed-loop control of the hydraulic cylinder in the existing technology.

[0006] In order to solve the above problems, in a first aspect, the present invention provides a position closed-loop control system for a hydraulic system, comprising: Linear displacement sensor, used to obtain the current position of the hydraulic cylinder piston rod; A programmable controller, for adjusting a PID output value according to a preset PID output range, and determining a control signal according to the adjusted PID output value; A proportional amplifier connected to the programmable controller, for converting the analog quantity in the control signal into an electrical signal; a proportional directional valve, connected to the proportional amplifier, for determining a valve opening according to the electrical signal; The hydraulic cylinder piston rod controls the moving speed according to the valve opening, and the programmable controller is further configured to generate a valve closing instruction when the current position and the target position coincide with each other.

[0007] In a possible implementation, the programmable controller further includes a PID controller; The PID controller is used to determine the adjusted PID output value by a PID algorithm with a preset PID output value upper limit and a preset PID output value lower limit as limits; The preset PID output range includes the preset PID output value upper limit and the preset PID output value lower limit.

[0008] In a possible implementation, the system further includes a self-tuning module, connected to the PID controller and the linear displacement sensor, respectively, for adaptively tuning the PID algorithm parameters of the PID controller according to the difference between the current position and the target position; The PID algorithm parameters include proportional gain, integral action time, differential action time, differential delay coefficient, proportional action weight, differential action weight and PID algorithm sampling time.

[0009] In a possible implementation, a digital-to-analog converter is further included, connected to the proportional amplifier, and configured to convert the adjusted PID output value into corresponding analog data and transmit the data to the proportional amplifier; The adjusted PID output value is a percentage signal in Real form.

[0010] In a possible implementation, the preset PID output value upper limit and the preset PID output value lower limit are both presented in percentage form; Wherein, the preset PID output value upper limit is related to the corresponding movement speed when the displacement of the hydraulic cylinder piston rod changes from small to large; The preset PID output value lower limit is related to the movement speed corresponding to the change in displacement of the hydraulic cylinder piston rod from large to small.

[0011] In a possible implementation, it further includes a human-computer interaction subsystem, which is signal-connected to the programmable controller; The human-computer interaction subsystem is used to obtain the preset PID output range.

[0012] In a possible implementation, the programmable controller is further connected to the proportional directional valve and the linear displacement sensor signal; The human-computer interaction subsystem is also used to display the displacement change information of the piston rod and to display the valve opening information in real time in the form of a trend graph.

[0013] In a second aspect, the present invention further provides a position closed-loop control method for a hydraulic system, comprising: Get the current position of the hydraulic cylinder piston rod; The PID output value is adjusted according to a preset PID output value upper limit and a preset PID output value lower limit, and a control signal is determined according to the adjusted PID output value; Converting the analog quantity in the control signal into an electrical signal; determining a valve opening according to the electrical signal, and controlling a moving speed of the hydraulic cylinder piston rod according to the valve opening; When the current position and the target position coincide with each other, a valve closing instruction is generated.

[0014] In a third aspect, the present invention also provides an electro-hydraulic proportional valve control system, comprising a memory and a processor, wherein the memory is used to store programs; the processor is coupled to the memory and is used to execute the programs stored in the memory to implement the steps in the position closed-loop control method of the hydraulic system described above.

[0015] In a fourth aspect, the present invention further provides a computer-readable storage medium for storing computer-readable programs or instructions, which, when executed by a processor, can implement the steps in the position closed-loop control method described above.

[0016] The beneficial effects of adopting the above embodiment are as follows: the present invention provides a position closed-loop control system for a hydraulic system, which can effectively ensure the range of the adjusted PID output value and thus ensure the size of the control signal by adjusting the PID output value within a preset PID output range; and because the electrical signal is converted from the analog quantity in the size of the control signal, the size of the control signal is related to the valve opening of the proportional directional valve, and the valve opening of the proportional directional valve is related to the movement speed of the hydraulic cylinder piston rod. Therefore, by controlling the range of the PID output value, the movement speed of the piston rod can be controlled, thereby avoiding excessive wear of the tunnel drilling robot arm. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic structural diagram of a first embodiment of a position closed-loop control system for a hydraulic system provided by the present invention; Figure 2 A schematic structural diagram of a second embodiment of a position closed-loop control system for a hydraulic system provided by the present invention; Figure 3 This is a flow chart of an embodiment of a position closed-loop control method for a hydraulic system provided by the present application; Figure 4 A schematic diagram showing the results of controlling the movement of a piston rod using a position closed-loop control method based on a hydraulic system provided by the present invention; Figure 5 This is a structural block diagram of an embodiment of the electro-hydraulic proportional valve control system provided by the present invention. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] It should be understood that the schematic drawings are not drawn to scale. The flowcharts used in the present invention illustrate operations implemented according to some embodiments of the present invention. It should be understood that the operations of the flowcharts can be implemented out of sequence, and steps that have no logical contextual relationship can be reversed in order or implemented simultaneously. In addition, those skilled in the art, guided by the content of the present invention, can add one or more other operations to the flowcharts or remove one or more operations from the flowcharts. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and / or processor systems and / or microcontroller systems.

[0020] The terms "first" and "second" in the embodiments of the present invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a technical feature designated as "first" or "second" may explicitly or implicitly include at least one such feature.

[0021] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] In order to solve the problem in the prior art of excessive wear of a tunnel drilling robot arm due to the inability to control the moving speed of a piston rod during position closed-loop control of a hydraulic cylinder, the present invention provides a position closed-loop control system and method for a hydraulic system, which are described in detail below.

[0023] like Figure 1 As shown, Figure 1 A schematic structural diagram of a first embodiment of a position closed-loop control system for a hydraulic system provided by the present invention includes: A linear displacement sensor 101 is used to obtain the current position of the hydraulic cylinder piston rod 102; A programmable controller 103 is configured to adjust a PID output value according to a preset PID output range and determine a control signal according to the adjusted PID output value; The proportional amplifier 104 is connected to the programmable controller 103 and is used to convert the analog quantity in the control signal into an electrical signal; Proportional directional valve 105, connected to proportional amplifier 104, for determining valve opening according to the electrical signal; The hydraulic cylinder piston rod 102 controls the moving speed according to the valve opening, and the programmable controller 103 is further used to generate a valve closing instruction when the current position and the target position coincide with each other.

[0024] In some embodiments of the present invention, a hydraulic cylinder is a hydraulic actuator that converts hydraulic energy into mechanical energy, performing linear reciprocating motion (or oscillating motion). A hydraulic cylinder essentially consists of a cylinder barrel and cylinder head, a piston and piston rod, a sealing device, a buffer device, and an exhaust device. In this application, the displacement and movement speed of the hydraulic cylinder piston rod 102 vary based on the valve opening of the proportional directional valve 105. The greater the valve opening of the proportional directional valve 105, the faster the movement speed of the hydraulic cylinder piston rod 102.

[0025] The linear displacement sensor 101 is a sensor that converts displacement into an electrical signal and is used to measure physical displacement.

[0026] Proportional amplifier 104 is an electronic device primarily used to amplify an input signal at a specific ratio and output it to a load for subsequent processing. Proportional amplifier 104 typically uses an operational amplifier (Op-Amp) as its core, achieving varying amplification factors by adjusting feedback resistors or capacitors.

[0027] The proportional directional valve 105 is a device that continuously and proportionally controls the direction and flow of the fluid in the hydraulic system according to the size of the input electrical signal.

[0028] Position closed-loop control is a commonly used control method based on the feedback principle. It monitors and controls the actual position of the object in real time, compares it with the set position value, and then calculates the deviation and generates a control signal to adjust the output of the controlled object to reach and maintain the desired position.

[0029] The programmable controller 103 is a digital computing electronic system designed for use in industrial environments. It uses a programmable memory to store instructions for performing logic operations, sequence control, timing, counting, and arithmetic operations. It controls various types of machinery or production processes through digital or analog input and output.

[0030] In this embodiment, by adjusting the PID output value with a preset PID output range as the limit, the range of the adjusted PID output value can be effectively guaranteed, thereby ensuring the size of the control signal; and because the electrical signal is converted from the analog quantity in the size of the control signal, the size of the control signal is related to the valve opening of the proportional directional valve 105, and the valve opening of the proportional directional valve 105 is related to the moving speed of the hydraulic cylinder piston rod 102. Therefore, by controlling the range of the PID output value, the moving speed of the piston rod can be controlled, thereby avoiding excessive wear of the tunnel drilling robot arm; and because the programmable controller 103 implements PID-regulated position closed-loop control, it is possible to achieve precise control of the position of the hydraulic cylinder piston rod 102.

[0031] In some embodiments of the present invention, in order to ensure the control effect of the programmable controller 103 on the PID output value, the position closed-loop control system of the hydraulic system further includes a PID controller; The PID controller is used to determine an adjusted PID output value through a PID algorithm with a preset PID output value upper limit and a preset PID output value lower limit as limits.

[0032] In some embodiments of the present invention, the position closed-loop control system of the hydraulic system further includes a digital-to-analog converter connected to the proportional amplifier 104 for converting the adjusted PID output value into corresponding analog data and transmitting it to the proportional amplifier 104; The adjusted PID output value is a percentage signal in Real form.

[0033] In this embodiment, the digital signal is converted into an analog signal that can be directly recognized by the proportional amplifier 104 through the digital-to-analog converter, so that the change of the data can be observed more intuitively.

[0034] In some embodiments of the present invention, the position closed-loop control system of the hydraulic system further includes a self-tuning module, connected to the PID controller and the linear displacement sensor 101, respectively, for adaptively tuning the PID algorithm parameters of the PID controller according to the difference between the current position and the target position; Among them, the PID algorithm parameters include proportional gain, integral action time, differential action time, differential delay coefficient, proportional action weight, differential action weight and PID algorithm sampling time.

[0035] It should be noted that the PID controller (Proportional-Integral-Derivative Controller) is a closed-loop feedback control algorithm widely used in industrial automation and electronic systems. By dynamically adjusting the parameters of the proportional (P), integral (I), and differential (D) links, the actual output of the system can quickly and stably track the target set value.

[0036] The PID algorithm utilizes the PID module embedded in programmable controller 103. The PID controller's setpoints are in millimeters (mm). The analog input serves as the process value source. The PID output uses a Real output value, expressed as a percentage rather than an analog value. This percentage output format provides greater flexibility and simplifies processing. The PID Real output requires further data processing by programmable controller 103 to meet the signal range and type requirements of proportional amplifier 104 and ensure the proper response of the proportional directional valve 105 spool.

[0037] The PID parameters in the PID algorithm processing include proportional gain, integral action time, differential action time, differential delay coefficient, proportional action weight, differential action weight and PID algorithm sampling time. These parameters can obtain the optimal value through optimization adjustment through the self-tuning function provided by the programmable controller 103.

[0038] The PID algorithm controls the PID output value during the PID controller's adjustment process by modifying the PID output upper and lower limits. This, in turn, controls the input signal to proportional amplifier 104, which in turn controls the opening and flow rate of proportional directional valve 105, thereby changing the movement speed of the hydraulic cylinder piston rod 102 and ultimately achieving speed regulation. Changing the PID output upper and lower limits will not affect the smooth and stable movement of the hydraulic cylinder piston rod 102 to the set position according to the adjusted parameters; it will only change the speed of the hydraulic cylinder piston rod 102 during operation. The PID output upper limit only affects the speed at which the displacement changes from small to large, while the PID output lower limit only affects the speed at which the displacement changes from large to small.

[0039] Since the PID algorithm only requires simply modifying the PID output value upper limit and the PID output value lower limit, rather than tediously changing the PID parameters such as proportional, integral and differential, the movement speed of the hydraulic cylinder piston rod 102 can be changed. Therefore, the processing method of this application is not only simple and easy to use, but also does not affect the accuracy of position control and the stability of system operation.

[0040] In some embodiments of the present invention, in order to simplify the operation and distinguish the moving direction of the hydraulic cylinder piston rod 102 and control the corresponding speed, the preset PID output value upper limit and the preset PID output value lower limit are both presented in the form of percentages; The preset upper limit of the PID output value is related to the corresponding moving speed when the displacement of the hydraulic cylinder piston rod 102 changes from small to large; The preset lower limit of the PID output value is related to the corresponding moving speed when the displacement of the hydraulic cylinder piston rod 102 changes from large to small.

[0041] In this embodiment, by expressing the preset PID output value upper limit and the preset PID output value lower limit in the form of a percentage, it helps the staff to estimate the moving speed of the hydraulic cylinder piston rod 102 appropriately. By controlling the speed of the hydraulic cylinder piston rod 102 in different movement directions, it effectively adapts to the needs of actual conditions.

[0042] In some embodiments of the present invention, in order to achieve adaptive adjustment of the preset variation range of the programmable controller 103, the position closed-loop control system of the hydraulic system further includes a human-machine interaction subsystem, which is signal-connected to the programmable controller 103; The human-computer interaction subsystem is used to obtain the preset PID output range.

[0043] Furthermore, the programmable controller 103 is also connected to the proportional directional valve 105 and the linear displacement sensor 101. The human-computer interaction subsystem is used to display the displacement change information of the piston rod and is also used to display the valve opening information in real time in the form of a trend chart.

[0044] In this embodiment, the preset PID output range, that is, the preset PID output value upper limit and the preset PID output value lower limit, is adaptively adjusted through the human-computer interaction subsystem; the human-computer interaction subsystem can also intuitively display to the outside the changes in some parameters within the position closed-loop control system of the hydraulic system.

[0045] In some embodiments of the present invention, in order to intuitively demonstrate the relationship between the various components of the position closed-loop control system of the hydraulic system, such as Figure 2 As shown, Figure 2 This is a structural diagram of the second embodiment of the position closed-loop control system of the hydraulic system provided by the present invention, wherein HMI refers to the human-machine interaction subsystem, and PLC refers to the programmable logic controller 103.

[0046] By transmitting the preset PID output value upper limit, the preset PID output value lower limit and the position feedback value measured by the linear displacement sensor 101 to the PLC, the PLC can calculate the valve opening of the proportional directional valve 105 through the PID algorithm in combination with the position setting value set by the HMI, that is, the target position, and then determine the movement speed of the hydraulic cylinder piston rod based on the valve opening.

[0047] In order to solve the above problems, the present application also provides a position closed-loop control method for a hydraulic system, such as Figure 3 As shown, Figure 3 This is a flow chart of an embodiment of a position closed-loop control method for a hydraulic system provided in this application, including: S301: Acquire the current position of the hydraulic cylinder piston rod; S302: adjusting the PID output value according to a preset PID output value upper limit and a preset PID output value lower limit, and determining a control signal according to the adjusted PID output value; In some embodiments of the present invention, the preset PID output range is presented in percentage form, specifically including (0%, 100%).

[0048] S303: Converting the analog quantity in the control signal into an electrical signal; S304: determining the valve opening according to the electrical signal, and controlling the moving speed of the hydraulic cylinder piston rod according to the valve opening; When the current position and the target position coincide with each other, a valve closing instruction is generated.

[0049] In this embodiment, by adjusting the PID output value within a preset PID output range, the range of the adjusted PID output value can be effectively guaranteed, thereby ensuring the size of the control signal. Because the electrical signal is converted from the analog quantity in the size of the control signal, the size of the control signal is related to the valve opening of the proportional directional valve, and the valve opening of the proportional directional valve is related to the movement speed of the hydraulic cylinder piston rod. Therefore, by controlling the range of the PID output value, the movement speed of the piston rod can be controlled, thereby avoiding excessive wear of the tunnel drilling robot arm.

[0050] In some embodiments of the present invention, for a specific valve opening of a proportional directional valve, there is a uniquely determined direction and flow rate of the hydraulic cylinder corresponding thereto. Therefore, the movement speed of the piston rod can be directly and accurately controlled according to the control signal.

[0051] In a specific embodiment, in order to intuitively demonstrate the effect of controlling the movement of the piston rod by the PID algorithm, as shown in FIG. Figure 4 As shown, Figure 4 This is a schematic diagram of the results of controlling piston rod movement according to an embodiment of the hydraulic system-based position closed-loop control method provided by the present invention. From right to left, curve A represents the PID_Output output value; curve B represents the valve opening; curve C represents the position setting value, that is, the target position; and curve D represents the displacement change curve.

[0052] As can be seen in the figure above, in stage 1, the target position is greater than the current position, and the piston rod extends. Because the distance to the target position is far, the valve opens to its maximum forward position, and the displacement curve changes steadily with a large positive slope. In stage 2, as the piston rod approaches the target position, the displacement curve changes steadily with a small positive slope. It should be noted that the piston rod speeds in stages 1 and 2 are different because the output value upper limits for stages 1 and 2 are different. In other words, by adjusting the output value upper limit, the piston rod extension speed can be adaptively adjusted.

[0053] In stage 4, the target position is less than the current position, and the piston rod retracts. Due to the distance from the target position, the valve opens in the reverse direction to its maximum, and the displacement curve changes steadily with a large negative slope. In stage 5, as the piston rod approaches the target position, the displacement curve changes steadily with a small negative slope. It should be noted that the piston rod speeds in stages 4 and 5 are different because the output lower limits for stages 4 and 5 are different. In other words, by adjusting the output lower limit, the piston rod retraction speed can be adaptively adjusted.

[0054] like Figure 5As shown, the present invention also provides an electro-hydraulic proportional valve control system 500. The electro-hydraulic proportional valve control system 500 includes a processor 501, a memory 502 and a display 503. Figure 5 Only some of the components of the electro-hydraulic proportional valve control system 500 are shown, but it should be understood that implementation of all of the shown components is not required, and more or fewer components may alternatively be implemented.

[0055] In some embodiments, the memory 502 may be an internal storage unit of the electro-hydraulic proportional valve control system 500, such as a hard disk or memory of the electro-hydraulic proportional valve control system 500. In other embodiments, the memory 502 may also be an external storage device of the electro-hydraulic proportional valve control system 500, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc., equipped on the electro-hydraulic proportional valve control system 500.

[0056] In some embodiments, the processor 501 may be a central processing unit (CPU), a microprocessor, or other data processing chip, configured to execute program codes or process data stored in the memory 502 , such as the position closed-loop control method of the hydraulic system in the present invention.

[0057] In some embodiments, display 503 can be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, or an OLED (Organic Light-Emitting Diode) touchscreen. Display 503 is used to display information about the electro-hydraulic proportional valve control system 500 and to present a visual user interface. Components 501-503 of the electro-hydraulic proportional valve control system 500 communicate with each other via a system bus.

[0058] In some embodiments of the present invention, when the processor 501 executes the position closed-loop control program of the hydraulic system in the memory 502, the following steps may be implemented: Get the current position of the hydraulic cylinder piston rod; The PID output value is adjusted according to a preset PID output value upper limit and a preset PID output value lower limit, and a control signal is determined according to the adjusted PID output value; Convert the analog quantity in the control signal into an electrical signal; The valve opening is determined according to the electrical signal, and the moving speed of the hydraulic cylinder piston rod is controlled according to the valve opening; When the current position and the target position coincide with each other, a valve closing instruction is generated.

[0059] It should be understood that, when the processor 501 executes the position closed-loop control program of the hydraulic system in the memory 502 , in addition to the above functions, it can also implement other functions. For details, please refer to the description of the above related method embodiments.

[0060] On the other hand, an embodiment of the present invention also provides a computer-readable storage medium, which is used to store computer-readable programs or instructions. When the program or instructions are executed by a processor, it can implement the steps or functions in the position closed-loop control method of the hydraulic system provided by the above-mentioned method embodiments.

[0061] Those skilled in the art will appreciate that all or part of the process flow of the above-described method embodiment can be implemented by instructing related hardware (such as a processor, controller, etc.) through a computer program, and the computer program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a magnetic disk, an optical disk, a read-only memory, or a random access memory.

[0062] The above is a detailed introduction to the position closed-loop control method and device of the hydraulic system provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A position closed-loop control system for a hydraulic system, characterized in that: include: Linear displacement sensor, used to obtain the current position of the hydraulic cylinder piston rod; A programmable controller, for adjusting a PID output value according to a preset PID output range, and determining a control signal according to the adjusted PID output value; A proportional amplifier connected to the programmable controller, for converting the analog quantity in the control signal into an electrical signal; a proportional directional valve, connected to the proportional amplifier, for determining a valve opening according to the electrical signal; The hydraulic cylinder piston rod controls the moving speed according to the valve opening, and the programmable controller is further configured to generate a valve closing instruction when the current position and the target position coincide with each other.

2. The position closed-loop control system of the hydraulic system according to claim 1, characterized in that: The programmable controller also includes a PID controller; The PID controller is used to determine the adjusted PID output value by a PID algorithm with a preset PID output value upper limit and a preset PID output value lower limit as limits; The preset PID output range includes the preset PID output value upper limit and the preset PID output value lower limit.

3. The position closed-loop control system of the hydraulic system according to claim 2, characterized in that: It also includes a self-tuning module, connected to the PID controller and the linear displacement sensor, respectively, for adaptively tuning the PID algorithm parameters of the PID controller according to the difference between the current position and the target position; The PID algorithm parameters include proportional gain, integral action time, differential action time, differential delay coefficient, proportional action weight, differential action weight and PID algorithm sampling time.

4. The position closed-loop control system of the hydraulic system according to claim 1, characterized in that: It also includes a digital-to-analog converter connected to the proportional amplifier, for converting the adjusted PID output value into corresponding analog data and transmitting it to the proportional amplifier; The adjusted PID output value is a percentage signal in Real form.

5. The position closed-loop control system of the hydraulic system according to claim 1, characterized in that: The preset PID output value upper limit and the preset PID output value lower limit are both presented in percentage form; Wherein, the preset PID output value upper limit is related to the corresponding movement speed when the displacement of the hydraulic cylinder piston rod changes from small to large; The preset PID output value lower limit is related to the movement speed corresponding to the change in displacement of the hydraulic cylinder piston rod from large to small.

6. The position closed-loop control system of the hydraulic system according to claim 1, characterized in that: It also includes a human-computer interaction subsystem connected to the programmable controller signal; The human-computer interaction subsystem is used to obtain the preset PID output range.

7. The position closed-loop control system of the hydraulic system according to claim 6, characterized in that: The programmable controller is also connected to the proportional directional valve and the linear displacement sensor signal; The human-computer interaction subsystem is also used to display the displacement change information of the piston rod and to display the valve opening information in real time in the form of a trend graph.

8. A method for position closed-loop control of a hydraulic system, applied to the position closed-loop control system of the hydraulic system according to any one of claims 1 to 7, characterized in that: include: Get the current position of the hydraulic cylinder piston rod; The PID output value is adjusted according to a preset PID output value upper limit and a preset PID output value lower limit, and a control signal is determined according to the adjusted PID output value; Converting the analog quantity in the control signal into an electrical signal; determining a valve opening according to the electrical signal, and controlling a moving speed of the hydraulic cylinder piston rod according to the valve opening; When the current position and the target position coincide with each other, a valve closing instruction is generated.

9. An electro-hydraulic proportional valve control system, characterized in that: It includes a memory and a processor, wherein the memory is used to store a program; the processor is coupled to the memory and is used to execute the program stored in the memory to implement the steps in the position closed-loop control method of the hydraulic system described in claim 8.

10. A computer-readable storage medium, characterized in that Used to store computer-readable programs or instructions, which, when executed by a processor, can implement the steps of the position closed-loop control method of the hydraulic system as described in claim 8.

Images