Hydraulic control method and system for a prestressed tensioning device

Abstract

The application relates to a hydraulic control method and system of prestressed tensioning equipment. The method comprises the following steps: determining a tension deviation according to the difference between a total tension and a corresponding first tension; obtaining an oil pressure compensation amount according to the tension deviation of each cycle, the total tension deviation, the difference between the tension deviation and the tension deviation of the previous cycle; obtaining a first integral term parameter according to the total tension deviation, and obtaining a first proportional term parameter according to the difference between the tension deviation and the tension deviation of the previous cycle; obtaining a second proportional term parameter according to the tension difference of the hydraulic cylinder, and obtaining a second integral term parameter according to the difference between the tension of the hydraulic cylinder and the corresponding second tension; adjusting the opening degree of a proportional overflow valve according to the first proportional term parameter, the first integral term parameter and the target total oil pressure of the next cycle, and adjusting the opening degree of a proportional reversing valve according to the second proportional term parameter and the second integral term parameter. The method can significantly improve the tensioning accuracy and reduce the wear.

Description

Technical Field

[0001] This application relates to the field of prestressed tensioning equipment technology, and in particular to a hydraulic control method and system for prestressed tensioning equipment. Background Technology

[0002] Prestressed tensioning equipment is specialized equipment used in engineering to apply prestress to components such as reinforcing bars, steel strands, and cables. By pre-establishing stress, it enhances the crack resistance and load-bearing capacity of the structure, and is widely used in bridges, buildings, and water conservancy projects. Its core function is to controllably output and maintain stable tension. Mainstream equipment often uses hydraulic drive due to its high output and flexible adjustment. Prestressed tensioning equipment mainly consists of four parts: actuator, power source, detection components, and control system. Among these, the hydraulic system is the core power and control carrier. The high-pressure oil output from the hydraulic pump, after being regulated by valve groups, drives the hydraulic cylinder to extend and retract, converting hydraulic energy into mechanical energy. The control of its pressure and flow rate directly determines the tension force and displacement accuracy.

[0003] The essence of controlling the hydraulic system in prestressed tensioning equipment is to achieve precise force-position output by adjusting pressure and flow. Specifically, this is achieved by regulating the pressure and flow of hydraulic oil through valve groups (such as relief valves and proportional directional valves), combined with sensor feedback to form a closed-loop control system, ensuring that the tensioning process proceeds according to preset parameters (such as target force value and loading rate). Existing control methods for the hydraulic system of double-cylinder prestressed tensioning equipment often focus only on the uniform regulation of overall pressure, neglecting the inherent differences between the two cylinders. Due to factors such as installation position deviations, manufacturing precision errors, and operating condition disturbances, even with identical control parameters, the actual output force and displacement of the two hydraulic cylinders will deviate to some extent. This directly leads to uncoordinated movements and unbalanced force distribution during actual tensioning, potentially causing excessive wear or even structural damage to critical components, as well as fluctuations in tensioning accuracy and unstable prestressing effects, making it difficult to meet the stringent requirements of prestressing application in engineering projects. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a hydraulic control method and system for prestressed tensioning equipment, the specific technical solution of which is as follows:

[0005] In a first aspect, a hydraulic control method for a prestressed tensioning device is provided, the method comprising:

[0006] The tension deviation for each cycle is determined based on the difference between the total tension of the two hydraulic cylinders and the corresponding first tension within each cycle of each loading level; the corresponding first tension is obtained based on the current total oil pressure in the oil circuit according to the preset correspondence between the total oil pressure and the tension for that loading level.

[0007] The oil pressure compensation for a given cycle is obtained by taking the tension deviation for each cycle at each loading level, the sum of the tension deviations for multiple cycles within that loading level, and the difference between the tension deviation for that cycle and the tension deviation for the previous cycle.

[0008] The first preset integral term parameter is obtained by adjusting the sum of the tensile deviations of multiple cycles within each loading level. The first preset proportional term parameter is obtained by adjusting the difference between the tensile deviation of each cycle and the tensile deviation of the previous cycle.

[0009] The second preset proportional term parameter is adjusted according to the difference in pulling force between the two hydraulic cylinders to obtain the second proportional term parameter. The second preset integral term parameter is adjusted according to the difference between the pulling force of each hydraulic cylinder and the corresponding second pulling force to obtain the second integral term parameter. The corresponding second pulling force is obtained based on the current oil pressure at the oil inlet of each hydraulic cylinder, according to the preset correspondence between the oil pressure and the pulling force at the oil inlet of that hydraulic cylinder.

[0010] The opening of the proportional relief valve is adjusted according to the first proportional term parameter, the first integral term parameter, and the target total oil pressure for the next cycle. The opening of the proportional directional valve is adjusted according to the second proportional term parameter and the second integral term parameter. The target total oil pressure for the next cycle is determined based on the oil pressure compensation amount for each cycle and the current total oil pressure in the oil circuit.

[0011] Optionally, the tension deviation for each cycle is determined based on the difference between the total tension of the two hydraulic cylinders and the corresponding first tension within each cycle of each loading level, including:

[0012] The tension of the two hydraulic cylinders is obtained by a tension sensor, and the sum of the tension of the two hydraulic cylinders is determined as the total tension of the two hydraulic cylinders.

[0013] Obtain the main hydraulic pump outlet pressure in each cycle of each loading level to get the current total oil pressure of the oil circuit, and determine the corresponding first tension from the preset correspondence between the total oil pressure and tension of the loading level based on the current total oil pressure of the oil circuit.

[0014] The tension deviation for each cycle is obtained by comparing the total tension of the two hydraulic cylinders with the corresponding first tension within each cycle of each loading level.

[0015] Optionally, the hydraulic pressure compensation for a given cycle is obtained based on the tension deviation for each cycle at each loading level, the sum of the tension deviations for multiple cycles within that loading level, and the difference between the tension deviation for that cycle and the tension deviation for the previous cycle. This includes:

[0016] Calculate the tensile deviation for each cycle and the sum of the tensile deviations for multiple cycles preceding that cycle within the same loading level to obtain the integral value of the tensile deviation for that cycle at that loading level.

[0017] The differential value of the tensile deviation for each cycle within each loading level is obtained by comparing the tensile deviation of the previous cycle with the tensile deviation of the previous cycle.

[0018] The oil pressure compensation amount for each cycle is determined by the ratio of the integral value of the tension deviation in each cycle to the number of cycles in the same loading level and the number of cycles before that cycle, the ratio of the differential value of the tension deviation in that cycle to the first tension corresponding to that cycle, and the current total oil pressure in the oil circuit.

[0019] Optionally, the first preset integral term parameter is obtained by adjusting the sum of the tensile deviations of multiple cycles within each loading level, and the first preset proportional term parameter is obtained by adjusting the difference between the tensile deviation of each cycle and the tensile deviation of the previous cycle, including:

[0020] The first preset integral term parameter is obtained by adjusting the product of the differential value of the tension deviation in each cycle and the preset value.

[0021] The first proportional term parameter is obtained by adjusting the product of the integral value of the tension deviation in each cycle and the preset value.

[0022] Optionally, the second preset proportional term parameter is adjusted according to the force difference between the two hydraulic cylinders to obtain the second proportional term parameter, and the second preset integral term parameter is adjusted according to the force of each hydraulic cylinder and the corresponding second force difference to obtain the second integral term parameter, including:

[0023] The tension of the two hydraulic cylinders is obtained by using a tension sensor, and the difference between the tensions of the two hydraulic cylinders is calculated to obtain the tension difference between the two hydraulic cylinders.

[0024] The second preset proportional parameter is adjusted according to the difference in pulling force between the two hydraulic cylinders to obtain the adjusted second proportional parameter.

[0025] Based on the current oil pressure at the inlet of each hydraulic cylinder, the second tension corresponding to the hydraulic cylinder is determined from the preset correspondence between the oil pressure and tension at the inlet of the hydraulic cylinder, and the difference between the tension of each hydraulic cylinder and the corresponding second tension in each cycle is calculated to obtain the tension difference value of the hydraulic cylinder in that cycle.

[0026] The tension error integral of a hydraulic cylinder is determined by summing the tension difference of each hydraulic cylinder in each cycle with the tension differences of multiple cycles preceding that cycle within the same loading level.

[0027] The second preset integral term parameter is obtained by adjusting the second integral term parameter based on the difference in the integral of the tension error between the two hydraulic cylinders.

[0028] Optionally, adjusting the opening of the proportional directional valve according to the second proportional term parameter and the second integral term parameter includes:

[0029] The first preset differential parameter is adjusted based on the difference between the tension difference of each hydraulic cylinder in each cycle and the tension difference in the previous cycle, the difference between the integral of the tension error of the two hydraulic cylinders in this cycle, and the difference between the integral of the tension error of the two hydraulic cylinders in the previous cycle, to obtain the first differential parameter.

[0030] The opening degree of the proportional directional valve is adjusted according to the second proportional term parameter, the second integral term parameter, and the first derivative parameter.

[0031] Optionally, before adjusting the opening of the proportional relief valve based on the first proportional term parameter, the first integral term parameter, and the target total oil pressure for the next cycle, the method further includes:

[0032] Based on the current total oil pressure of the oil circuit in each cycle of each loading level, the total oil pressure of the oil circuit in the next cycle is determined from the preset correspondence between the total oil pressure of the oil circuit in that loading level and the loading duration.

[0033] The target total oil pressure for the next cycle is determined based on the oil pressure compensation amount for each cycle at each loading level and the total oil pressure in the oil circuit for the next cycle.

[0034] Optionally, the opening of the proportional relief valve is adjusted according to the first proportional term parameter, the first integral term parameter, and the target total oil pressure for the next cycle, including:

[0035] The first proportional term parameter is adjusted based on the difference between the target total oil pressure for the next cycle and the current total oil pressure in the oil circuit for that cycle, to obtain the adjusted first proportional term parameter.

[0036] Based on the loading duration corresponding to each cycle of each loading level, the target oil pressure for that cycle is determined from the preset correspondence between the total oil pressure and the loading duration of the oil circuit for that loading level.

[0037] The first integral term parameter is adjusted based on the difference between the target oil pressure for each cycle and the current total oil pressure in the oil circuit for that cycle, resulting in the adjusted first integral term parameter.

[0038] The preset second differential parameter is adjusted based on the difference between the target oil pressure and the starting oil pressure of each cycle, and the difference between the current total oil pressure of the oil circuit and the starting oil pressure of the cycle, to obtain the adjusted second differential parameter; the starting oil pressure of each cycle is the target oil pressure of the previous cycle.

[0039] The opening degree of the proportional relief valve is adjusted according to the adjusted first proportional term parameter, the adjusted first integral term parameter, and the adjusted second derivative parameter.

[0040] Secondly, a hydraulic control system for a prestressed tensioning device is provided, the system comprising:

[0041] The first determining module is used to determine the tension deviation of each cycle based on the difference between the total tension of the two hydraulic cylinders and the corresponding first tension in each cycle of each loading level; the corresponding first tension is obtained based on the current total oil pressure of the oil circuit according to the preset correspondence between the total oil pressure and the tension of the loading level.

[0042] The second determining module is used to obtain the oil pressure compensation amount for the current cycle based on the tension deviation amount for each cycle of each loading level, the sum of the tension deviation amounts for multiple cycles within the loading level, and the difference between the tension deviation amount for the current cycle and the tension deviation amount for the previous cycle.

[0043] The first adjustment module is used to adjust the first preset integral term parameter according to the sum of the tensile deviations of multiple cycles within each loading level to obtain the first integral term parameter, and to adjust the first preset proportional term parameter according to the difference between the tensile deviation of each cycle and the tensile deviation of the previous cycle to obtain the first proportional term parameter.

[0044] The second adjustment module is used to adjust the second preset proportional term parameter according to the tension difference between the two hydraulic cylinders to obtain the second proportional term parameter, and to adjust the second preset integral term parameter according to the tension of each hydraulic cylinder and the difference between the corresponding second tension to obtain the second integral term parameter; the corresponding second tension is obtained based on the current oil pressure of the hydraulic cylinder inlet according to the preset correspondence between the oil pressure and the tension at the oil inlet of each hydraulic cylinder.

[0045] The third adjustment module is used to adjust the opening of the proportional relief valve according to the first proportional term parameter, the first integral term parameter and the target total oil pressure of the next cycle, and to adjust the opening of the proportional directional valve according to the second proportional term parameter and the second integral term parameter; the target total oil pressure of the next cycle is determined according to the oil pressure compensation amount of each cycle and the current total oil pressure of the oil circuit.

[0046] Optionally, the first determining module is also used for:

[0047] The tension of the two hydraulic cylinders is obtained by a tension sensor, and the sum of the tension of the two hydraulic cylinders is determined as the total tension of the two hydraulic cylinders.

[0048] Obtain the main hydraulic pump outlet pressure in each cycle of each loading level to get the current total oil pressure of the oil circuit, and determine the corresponding first tension from the preset correspondence between the total oil pressure and tension of the loading level based on the current total oil pressure of the oil circuit.

[0049] The tension deviation for each cycle is obtained by comparing the total tension of the two hydraulic cylinders with the corresponding first tension within each cycle of each loading level.

[0050] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of this application.

[0051] This application offers the following advantages: By using a dual-cylinder hydraulic control loop, the second proportional term parameter and the second integral term parameter are adjusted according to the tension difference between the two hydraulic cylinders and the difference between the tension of each cylinder and the corresponding second tension. This, in turn, controls the opening of the proportional directional valve, effectively coordinating the output of the two cylinders and avoiding force imbalance caused by different outputs with the same parameters, ensuring uniform displacement of the two cylinders. The hydraulic compensation amount, determined based on the tension deviation in each cycle, the sum of tension deviations across multiple cycles within the loading level, and their changes, combined with the first proportional term parameter and the first integral term parameter adjusted based on the sum of tension deviations and their changes, dynamically corrects the correspondence between theoretical hydraulic pressure and tension, ensuring that the actual total tension accurately matches the design target, significantly improving tensioning accuracy. Through the dual-cylinder collaboration and precise tension control mechanism, unilateral overload and uneven system stress are effectively avoided, reducing abnormal wear on key components such as hydraulic cylinders and valve groups, extending equipment lifespan, and ensuring balanced stress on the engineering structure during tensioning, preventing structural damage caused by localized stress concentration, and improving pre-tensioning quality and long-term safety. Attached Figure Description

[0052] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A flowchart of a hydraulic control method for a prestressed tensioning device in one embodiment;

[0054] Figure 2 This is a schematic diagram of the hydraulic control system of a prestressed tensioning device in one embodiment;

[0055] Figure 3 This is a schematic diagram of the structure of an electronic device in one embodiment. Detailed Implementation

[0056] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a hydraulic control method and system for a prestressed tensioning device proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0058] The specific scheme of the hydraulic control method for a prestressed tensioning device provided in this application is described below with reference to the accompanying drawings. For example... Figure 1 As shown, the method includes:

[0059] S11. Determine the tension deviation for each cycle based on the difference between the total tension of the two hydraulic cylinders and the corresponding first tension within each cycle of each loading level.

[0060] The corresponding first tension is obtained based on the current total oil pressure of the oil circuit, according to the preset relationship between the total oil pressure and the tension at this loading level.

[0061] The dual-cylinder prestressed tensioning device provided in this application comprises a hydraulic system mainly consisting of two hydraulic cylinders, a proportional directional valve, a proportional relief valve, and a detection unit. The pressure oil output from the hydraulic pump, after being adjusted by the proportional relief valve to regulate the total system pressure, enters the proportional directional valve. The proportional directional valve then distributes the oil to the two hydraulic cylinders according to control commands to drive their operation. The detection unit includes: 1. a total oil pressure sensor installed on the main oil circuit between the proportional relief valve and the proportional directional valve, used to detect the total oil pressure of the oil circuit; 2. branch oil pressure sensors installed on the oil inlet branches of the two hydraulic cylinders; 3. a force sensor for detecting the output tension of the two hydraulic cylinders and a displacement sensor for detecting piston displacement. The displacement sensors are installed along the axis of the rodless chamber bottom of the two hydraulic cylinders, one per cylinder, symmetrically arranged. The branch oil pressure sensors are installed in the branch oil circuits at the oil inlet of the rodless chamber of the two hydraulic cylinders, one per cylinder, measuring the actual oil pressure of a single cylinder. The displacement and oil pressure data of the two cylinders are collected through the sensors, with a data acquisition frequency... The controller filters the collected signals and performs linear calibration. Based on the feedback signals from the sensors, it outputs control signals to the proportional relief valve and the proportional directional valve respectively, so as to realize closed-loop control of the total system pressure and coordinated control of the synchronous action of the two hydraulic cylinders.

[0062] The proportional directional valve controls the oil inlet and outlet flow of a single cylinder, adjusting the piston's movement speed and displacement. The PID (Proportional-Integral-Derivative) algorithm increases or decreases the valve opening of a specific cylinder to correct the displacement. The proportional relief valve regulates the system's total pressure, matching the cable preload requirements. During staged loading, the PID adjusts the valve opening based on force sensor data to control the pressure rise rate and prevent sudden force increases.

[0063] This application addresses the dual-cylinder hydraulic system of prestressed tensioning equipment, setting up two control loops. The first loop is an overall hydraulic pressure control loop, which controls the proportional relief valve and, combined with a staged loading mechanism, uses PID control to control the hydraulic pressure, ensuring that the tension and hydraulic pressure are applied according to the design. The second loop is a dual-cylinder hydraulic pressure control loop, which controls the proportional directional valve. Adjustments are made based on sensor data from both cylinders, and the PID parameters are adjusted in conjunction with the staged loading mechanism to ensure more uniform and consistent displacement of the two cylinders during the decomposed loading process.

[0064] To avoid instantaneous impact and equipment deformation during prestressing tensioning, the prestress is applied in stages. Each loading stage includes multiple cycles, each lasting 50 ms, with data acquisition performed once per cycle. At each loading stage, the tension force is increased at a preset loading rate to the target force value for that stage, and force fluctuations within that stage are controlled within allowable accuracy ranges. The loading stages in this application are shown in Table 1.

[0065] Table 1 Load Level Table

[0066]

[0067] The tensioning process involves four tensioning stages, meaning there are four loading levels. Each stage of tensioning must be completed before proceeding to the next stage, with a 2-10 second interval between each stage. The loading levels are categorized into four percentage levels, with the percentage indicating the percentage of the target tension to be achieved at that stage, and the precision indicating the upper limit of error allowed at the end of that stage.

[0068] The overall hydraulic control loop controls the proportional relief valve, and combined with the staged loading mechanism, uses PID control to control the hydraulic pressure, ensuring that the tension and hydraulic pressure are applied according to the design. During prestressing tensioning, staged tensioning makes the stress more stable. To achieve this stability, the force often needs to be applied uniformly, i.e., linearly. Furthermore, the different stages of the stage have different purposes and requirements (e.g., the first stage is pre-loading, the last stage requires stable loading), therefore the required loading rates differ. Based on these requirements, different loading rates are set for different stages, as shown in Table 2.

[0069] Table 2 Load Level and Load Rate Correspondence Table

[0070]

[0071] Since the tension force fluctuates during the actual loading process, hydraulic pressure is used as the control loop for overall control of the hydraulic system to suppress fluctuations. By using the loading rate and target force value, different levels of force are obtained, resulting in target loading curves for different loading levels.

[0072] When the theoretical loading curve deviates, the theoretical oil pressure cannot correspond to the actual tension. Therefore, the theoretical oil pressure is compensated by the deviation between the actual tension and the theoretical tension, and the corresponding PID parameters are adjusted to adapt to the compensation oil pressure.

[0073] In one embodiment, the tension deviation for each cycle is determined based on the difference between the total tension of the two hydraulic cylinders and the corresponding first tension within each cycle of each loading level, including:

[0074] The tension of the two hydraulic cylinders is obtained by a tension sensor, and the sum of the tension of the two hydraulic cylinders is determined as the total tension of the two hydraulic cylinders.

[0075] Obtain the main hydraulic pump outlet pressure in each cycle of each loading level to get the current total oil pressure of the oil circuit, and determine the corresponding first tension from the preset correspondence between the total oil pressure and tension of the loading level based on the current total oil pressure of the oil circuit.

[0076] The tension deviation for each cycle is obtained by comparing the total tension of the two hydraulic cylinders with the corresponding first tension within each cycle of each loading level.

[0077] The tensions FL and FR of the two hydraulic cylinders are obtained by a tension sensor. The total tension is obtained by summing the tensions of the two hydraulic cylinders. The formula for calculating the total tension F is: F = FL + FR.

[0078] At each loading level, the total hydraulic pump outlet pressure is obtained for each cycle to determine the current total oil pressure in the oil circuit. Then, based on the current total oil pressure in the oil circuit, the corresponding first tension is determined from the preset correspondence between the total oil pressure and tension for this loading level. The pre-defined relationship between total oil pressure and tensile force for each loading level can be obtained through calibration experiments. Then, the tensile force deviation for that cycle is calculated. The calculation formula is: .

[0079] S12. Based on the tension deviation of each cycle at each loading level, the sum of the tension deviations of multiple cycles within the loading level, and the difference between the tension deviation of this cycle and the tension deviation of the previous cycle, the oil pressure compensation amount for this cycle is obtained.

[0080] The oil pressure compensation is used to correct the total oil pressure in the current oil circuit to compensate for the tension deviation caused by system friction, leakage and changes in operating conditions.

[0081] In one embodiment, the hydraulic pressure compensation amount for a given cycle is obtained based on the tension deviation for each cycle at each loading level, the sum of the tension deviations for multiple cycles within that loading level, and the difference between the tension deviation for that cycle and the tension deviation for the previous cycle, including:

[0082] Calculate the tensile deviation for each cycle and the sum of the tensile deviations for multiple cycles preceding that cycle within the same loading level to obtain the integral value of the tensile deviation for that cycle at that loading level.

[0083] The differential value of the tensile deviation for each cycle within each loading level is obtained by comparing the tensile deviation of the previous cycle with the tensile deviation of the previous cycle.

[0084] The oil pressure compensation amount for each cycle is determined by the ratio of the integral value of the tension deviation in each cycle to the number of cycles in the same loading level and the number of cycles before that cycle, the ratio of the differential value of the tension deviation in that cycle to the first tension corresponding to that cycle, and the current total oil pressure in the oil circuit.

[0085] Because the actual tensile force may fluctuate, and this fluctuation will cause the tensile force to change up and down, resulting in a systematic deviation that causes the tensile force to continuously decrease, the sum of the tensile force deviations for each cycle and the previous cycles within the same loading level is calculated to obtain the integral value of the tensile force deviation for that cycle at that loading level. The calculation formula is: Where sum() is the summation formula. This indicates the sum of the tension deviation for each cycle and the tension deviations for multiple cycles preceding this cycle within the same loading level. The larger the integral value of the tension deviation, the greater the system tension error, and the greater the oil pressure compensation should be.

[0086] System deviations, such as friction, will increase with increasing tension, or may not be immediately apparent. Therefore, it's necessary to consider the differential change in tension deviation. A larger differential value indicates a greater change in tension deviation, suggesting that the deviation has not yet reached a stable value and the actual deviation will be larger. Conversely, a smaller differential value indicates a more stable tension deviation, meaning the obtained deviation has reached a stable value. Therefore, the differential value of the tension deviation for each cycle can be obtained by comparing the tension deviation of each cycle with the deviation of the previous cycle. .

[0087] Hydraulic pressure compensation The calculation formula is:

[0088] ;

[0089] in, The oil pressure compensation amount for each cycle. This represents the current total oil pressure in the oil circuit, which is also the current total oil pressure in the oil circuit for this cycle. This represents the integral value of the tensile deviation for that cycle, where N is the number of tensile deviations, i.e., the number of tensile deviations in that cycle and in the preceding cycles within the same loading level. This is the first tension corresponding to this cycle. This is the differential value of the tension deviation during this period.

[0090] S13. Adjust the first preset integral term parameter according to the sum of the tensile deviations of multiple cycles within each loading level to obtain the first integral term parameter. Adjust the first preset proportional term parameter according to the difference between the tensile deviation of each cycle and the tensile deviation of the previous cycle to obtain the first proportional term parameter.

[0091] In one embodiment, a first preset integral term parameter is obtained by adjusting the first integral term parameter based on the sum of the tensile deviations over multiple cycles within each loading level; and a first preset proportional term parameter is obtained by adjusting the first proportional term parameter based on the difference between the tensile deviation of each cycle and the tensile deviation of the previous cycle. This includes:

[0092] The first preset integral term parameter is obtained by adjusting the product of the differential value of the tension deviation in each cycle and the preset value.

[0093] The first proportional term parameter is obtained by adjusting the product of the integral value of the tension deviation in each cycle and the preset value.

[0094] The first preset integral term parameter and the first preset proportional term parameter can be set according to the actual situation.

[0095] When adjusting PID parameters, it is necessary to base the adjustments on the above data: integral of tension deviation. The larger the value, the greater the short-term pressure required, and the larger the proportional term parameter should be; the larger the derivative of the tension deviation, the more unstable the current system deviation, and the larger the integral term parameter should be; therefore, the proportional and integral term parameters should be adjusted as follows:

[0096] ;

[0097] ;

[0098] in, The first proportional term parameter corresponding to each cycle, The first preset ratio parameter, KP, remains constant during each cycle calculation. This is a preset value, which can be 0.15. for Normalization function, This is the integral value of the tension deviation for that period. The parameter for the first integral term corresponding to this period. The first preset integral term parameter, KI, remains unchanged during each cycle of calculation. This is a preset value, which can be 0.15. This is the differential value of the tension deviation during this period.

[0099] S14. Adjust the second preset proportional term parameter according to the difference in pulling force between the two hydraulic cylinders to obtain the second proportional term parameter. Adjust the second preset integral term parameter according to the difference between the pulling force of each hydraulic cylinder and the corresponding second pulling force to obtain the second integral term parameter.

[0100] The corresponding second pulling force is obtained based on the current oil pressure at the oil inlet of each hydraulic cylinder, according to the preset correspondence between the oil pressure and the pulling force at the oil inlet of that hydraulic cylinder.

[0101] In one embodiment, the second preset proportional term parameter is adjusted according to the force difference between the two hydraulic cylinders to obtain the second proportional term parameter, and the second preset integral term parameter is adjusted according to the force of each hydraulic cylinder and the corresponding second force difference to obtain the second integral term parameter, including:

[0102] The tension of the two hydraulic cylinders is obtained by using a tension sensor, and the difference between the tensions of the two hydraulic cylinders is calculated to obtain the tension difference between the two hydraulic cylinders.

[0103] The second preset proportional parameter is adjusted according to the difference in pulling force between the two hydraulic cylinders to obtain the adjusted second proportional parameter.

[0104] Based on the current oil pressure at the inlet of each hydraulic cylinder, the second tension corresponding to the hydraulic cylinder is determined from the preset correspondence between the oil pressure and tension at the inlet of the hydraulic cylinder, and the difference between the tension of each hydraulic cylinder and the corresponding second tension in each cycle is calculated to obtain the tension difference value of the hydraulic cylinder in that cycle.

[0105] The tension error integral of a hydraulic cylinder is determined by summing the tension difference of each hydraulic cylinder in each cycle with the tension differences of multiple cycles preceding that cycle within the same loading level.

[0106] The second preset integral term parameter is obtained by adjusting the second integral term parameter based on the difference in the integral of the tension error between the two hydraulic cylinders.

[0107] When performing tension control with dual hydraulic cylinders, due to manufacturing errors and other reasons, the correspondence between the oil pressure and tension of the two hydraulic cylinders may deviate to some extent. That is, even using exactly the same control parameters, the actual output force and displacement will differ. Therefore, a second preset proportional parameter can be set according to the actual situation. Second preset integral term parameters and the first preset differential parameter .

[0108] For the two hydraulic cylinders, the oil pressure at the oil inlet of hydraulic cylinder a is obtained respectively. And the oil pressure at the oil inlet of hydraulic cylinder b Simultaneously, the tension of hydraulic cylinder a is obtained through a tension sensor. The pulling force of hydraulic cylinder b Because the tension fluctuates significantly and is unstable, the tension data is first filtered by mean filtering to remove the fluctuations. Then, the tension difference between the two hydraulic cylinders after mean filtering is calculated. The calculation formula is: The greater the tension difference, the greater the difference in tension between the two cylinders, and the more uneven the stress on the overall tensioning equipment. In this case, a larger adjustment is required. The second preset proportional parameter can be adjusted based on the tension difference between the two hydraulic cylinders to obtain the adjusted second proportional parameter. The calculation formula is: .

[0109] The pre-defined relationship between oil pressure and tension at the inlet of each hydraulic cylinder can be obtained through calibration experiments. Taking hydraulic cylinder a as an example, based on the current oil pressure at the inlet of hydraulic cylinder a in each cycle, the second tension corresponding to hydraulic cylinder a is determined from the relationship between oil pressure and tension at the inlet of hydraulic cylinder a. Then calculate the tension of hydraulic cylinder a. With the corresponding second tension The difference is used to obtain the tension difference of hydraulic cylinder a in that cycle. Then, the sum of the tension difference of hydraulic cylinder a in each cycle and the tension differences of multiple cycles prior to that cycle within the same loading level is calculated to obtain the integral of the tension error of hydraulic cylinder a. The calculation formula is: Where sum() is the summation formula. This is the sum of the tension difference of hydraulic cylinder a in each cycle and the tension differences of multiple cycles preceding that cycle within the same loading level. This indicates the deviation of oil pressure and tension in hydraulic cylinder a. Similarly, the integral of the tension error in hydraulic cylinder b is obtained. .

[0110] The deviation of the hydraulic cylinders indicates the systematic deviation between the actual and theoretical pulling force. Therefore, the difference in the integral of the systematic error between the two hydraulic cylinders can better represent the systematic deviation between them. Thus, the integral difference of the pulling force error between the two hydraulic cylinders is calculated. integral difference of tensile error The calculation formula is: .

[0111] The greater the system deviation difference between the two hydraulic cylinders, the greater the difference in actual pulling force corresponding to the same oil pressure in the two hydraulic cylinders. In this case, the adjustment amount should be larger. Based on the difference in the integral of the pulling force error between the two hydraulic cylinders, the second preset integral term parameter is adjusted to obtain the second integral term parameter. The calculation formula is: , For the parameters of the second integral term, For the second preset integral term parameters, This is the integral difference of the tension error.

[0112] S15. Adjust the opening of the proportional relief valve according to the first proportional term parameter, the first integral term parameter and the target total oil pressure of the next cycle, and adjust the opening of the proportional directional valve according to the second proportional term parameter and the second integral term parameter.

[0113] The target total oil pressure for the next cycle is determined based on the oil pressure compensation amount for each cycle and the current total oil pressure in the oil circuit.

[0114] In one embodiment, adjusting the opening degree of the proportional directional valve according to the second proportional term parameter and the second integral term parameter includes:

[0115] The first preset differential parameter is adjusted based on the difference between the tension difference of each hydraulic cylinder in each cycle and the tension difference in the previous cycle, the difference between the integral of the tension error of the two hydraulic cylinders in this cycle, and the difference between the integral of the tension error of the two hydraulic cylinders in the previous cycle, to obtain the first differential parameter.

[0116] The opening degree of the proportional directional valve is adjusted according to the second proportional term parameter, the second integral term parameter, and the first derivative parameter.

[0117] The differential term represents the rate of change. Therefore, by calculating the difference between the tension difference of each hydraulic cylinder in each cycle and the tension difference in the previous cycle, the differential value of the tension is obtained. Next, calculate the difference between the integrals of the pulling force errors of the two hydraulic cylinders in this cycle and the difference between the integrals of the pulling force errors of the two hydraulic cylinders in the previous cycle. The difference between the former (the difference between the integrals of the pulling force errors of the two hydraulic cylinders in this cycle) and the latter (the difference between the integrals of the pulling force errors of the two hydraulic cylinders in the previous cycle) is determined as the differential value of the system deviation. First differential parameter The calculation formula is: ,in, The first preset differential parameter, Let be the differential value of the tension. This is the differential value of the system deviation.

[0118] Finally, the overall adjustment amount W1 is calculated. The formula for calculating the overall adjustment amount W1 is: , For the second proportional term parameter, For the parameters of the second integral term, The first differential parameter is used. The calculated overall adjustment W1 is converted into a physical signal (usually current or voltage) to drive the proportional directional valve, which redistributes the flow to the two hydraulic cylinders by changing the valve spool position.

[0119] In one embodiment, before adjusting the opening of the proportional relief valve based on the first proportional term parameter, the first integral term parameter, and the target total oil pressure for the next cycle, the method further includes:

[0120] Based on the current total oil pressure of the oil circuit in each cycle of each loading level, the total oil pressure of the oil circuit in the next cycle is determined from the preset correspondence between the total oil pressure of the oil circuit in that loading level and the loading duration.

[0121] The target total oil pressure for the next cycle is determined based on the oil pressure compensation amount for each cycle at each loading level and the total oil pressure in the oil circuit for the next cycle.

[0122] Calibration experiments can be used to obtain calibration curves for different loading forces and corresponding oil pressures, i.e., curves showing the relationship between loading force and oil pressure. By using the target loading force and the target percentage for different loading levels, the graded target oil pressure for each loading level can be obtained. and initial stage oil pressure Where i represents the loading level, and then through calibration experiments, the loading rates corresponding to different levels are used to obtain the corresponding loading curves. That is, the pre-defined relationship between the total oil pressure and loading time of the oil circuit for each loading level is the loading curve. The linear equation representing the loading curve starts from the oil pressure at the initial stage of the loading level. The endpoint is the target oil pressure for that loading level. The slope of the curve corresponds to the graded loading rate. The horizontal axis of the loading curve represents the loading time, and the vertical axis represents the oil pressure.

[0123] When performing overall oil pressure control, PID control is used based on the difference between the theoretical oil pressure and the actual monitored oil pressure. At the same time, considering the static deviation and tension fluctuation of the control system, the PID parameters and theoretical oil pressure are adjusted to enable better control.

[0124] Therefore, the current total oil pressure in the oil circuit can be obtained through the total oil pressure sensor in the main oil circuit. Then, using the load curve of that load level and the current load time t, combined with the control cycle... The total oil pressure Pn of the oil circuit in the next cycle is determined from the preset correspondence between the total oil pressure and the loading time of the oil circuit at this loading level. The corresponding oil pressure in the loading curve at any given time is then used to determine the total oil pressure in the oil circuit for the next cycle. Oil pressure compensation amount for the current cycle The sum of these values ​​is determined as the target total oil pressure for the next cycle. .

[0125] In one embodiment, adjusting the opening of the proportional relief valve based on the first proportional term parameter, the first integral term parameter, and the target total oil pressure for the next cycle includes:

[0126] The first proportional term parameter is adjusted based on the difference between the target total oil pressure for the next cycle and the current total oil pressure in the oil circuit for that cycle, to obtain the adjusted first proportional term parameter.

[0127] Based on the loading duration corresponding to each cycle of each loading level, the target oil pressure for that cycle is determined from the preset correspondence between the total oil pressure and the loading duration of the oil circuit for that loading level.

[0128] The first integral term parameter is adjusted based on the difference between the target oil pressure for each cycle and the current total oil pressure in the oil circuit for that cycle, resulting in the adjusted first integral term parameter.

[0129] The preset second differential parameter is adjusted based on the difference between the target oil pressure and the starting oil pressure of each cycle, and the difference between the current total oil pressure of the oil circuit and the starting oil pressure of the cycle, to obtain the adjusted second differential parameter; the starting oil pressure of each cycle is the target oil pressure of the previous cycle.

[0130] The opening degree of the proportional relief valve is adjusted according to the adjusted first proportional term parameter, the adjusted first integral term parameter, and the adjusted second derivative parameter.

[0131] Based on the target total oil pressure for the next cycle. and the current total oil pressure of the oil circuit in this cycle The difference is used to adjust the parameter of the first proportional term, resulting in the adjusted parameter of the first proportional term. The calculation formula is: , For the first proportional term parameter, it should be noted that when the system is in its initial state, The first preset proportional parameter KP is taken, that is, before the first control cycle and the first parameter update, the system uses the initial preset parameters.

[0132] Based on the loading duration corresponding to each cycle of each loading level, the target oil pressure for that cycle is determined from the preset correspondence between the total oil pressure and the loading duration of the oil circuit for that loading level. Then calculate the total oil pressure of the oil circuit. The difference between the target oil pressure and the target oil pressure is calculated using the following formula: , The oil pressure difference is calculated, and it is integrated to obtain the sum of the oil pressure differences for this cycle and multiple cycles prior to this cycle at the same loading level. Calculate the adjusted parameters of the first integral term. The calculation formula is: ,in, For the parameters of the first integral term, it should be noted that when the system is in its initial state, Take the first preset integral term parameters That is, before the first control cycle and the first parameter update, the system uses the initial preset parameters.

[0133] Differential term adjustment is mainly based on the change in error. This application performs differential term adjustment by decomposing the loading stage progress. When the loading progress is closer to the starting point, a certain error is allowed during loading, and the allowable adjustment amount is larger. When the progress is closer to the end point, the loading needs to be more precise to avoid excessive adjustment leading to over-adjustment. Therefore, the current total oil pressure of the oil circuit is obtained. Based on the target oil pressure for each cycle. The loading progress D is calculated by taking the difference between the starting oil pressure of this cycle (i.e., the target oil pressure of the previous cycle) and the difference between the current total oil pressure of the oil circuit in this cycle and the starting oil pressure of this cycle. The formula for calculating the loading progress D is as follows: ,in, This represents the current total oil pressure in the oil circuit. The initial oil pressure for each cycle, The target oil pressure for this cycle is then calculated, followed by the adjustment of the second integral term parameters. : ,in, To preset the second differential parameter, This indicates the loading progress.

[0134] Finally, the total adjustment amount is obtained. Total adjustment amount The calculation formula is: ,in, This represents the total adjustment amount. The first proportional term parameter after adjustment. The adjusted parameters for the first integral term. The parameter is the adjusted second integral term parameter.

[0135] Based on the total adjustment amount A corresponding control signal is generated and drives the electromagnet of the proportional relief valve, causing its valve core to produce a displacement corresponding to the magnitude of the control signal, thereby linearly adjusting the opening degree of the proportional relief valve; wherein, when When the value is positive, the opening is increased to reduce the total oil pressure of the system. When the value is negative, the opening is reduced to increase the total oil pressure of the system, thereby achieving the desired effect through the adjustment amount. Closed-loop control of the system's total oil pressure.

[0136] Through a dual-cylinder hydraulic control loop, the second proportional term parameter and the second integral term parameter are adjusted according to the tension difference between the two hydraulic cylinders and the difference between the tension of each cylinder and the corresponding second tension. This, in turn, controls the opening of the proportional directional valve, effectively coordinating the output of the two cylinders and avoiding force imbalance caused by different outputs with the same parameters, ensuring uniform displacement of the two cylinders. The hydraulic compensation amount, determined based on the tension deviation in each cycle, the sum of tension deviations across multiple cycles within the loading level, and their changes, is combined with the first proportional term parameter and the first integral term parameter adjusted based on the sum of tension deviations and their changes. This dynamically corrects the correspondence between theoretical hydraulic pressure and tension, ensuring that the actual total tension accurately matches the design target, significantly improving tensioning accuracy. Through the dual-cylinder collaboration and precise tension control mechanism, unilateral overload and uneven system stress are effectively avoided, reducing abnormal wear on key components such as hydraulic cylinders and valve groups, extending equipment lifespan, and ensuring balanced stress on the engineering structure during tensioning. This prevents structural damage caused by localized stress concentration, improving pre-tensioning quality and long-term safety.

[0137] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0138] This application also provides a hydraulic control system for a prestressed tensioning device, such as... Figure 2 As shown, the system includes:

[0139] The first determining module 21 is used to determine the tension deviation of each cycle based on the difference between the total tension of the two hydraulic cylinders and the corresponding first tension in each cycle of each loading level; the corresponding first tension is obtained based on the current total oil pressure of the oil circuit according to the preset correspondence between the total oil pressure and the tension of the loading level.

[0140] The second determining module 22 is used to obtain the oil pressure compensation amount for the current cycle based on the tension deviation amount for each cycle of each loading level, the sum of the tension deviation amounts for multiple cycles within the loading level, and the difference between the tension deviation amount for the current cycle and the tension deviation amount for the previous cycle.

[0141] The first adjustment module 23 is used to adjust the first preset integral term parameter according to the sum of the tensile deviations of multiple cycles within each loading level to obtain the first integral term parameter, and to adjust the first preset proportional term parameter according to the difference between the tensile deviation of each cycle and the tensile deviation of the previous cycle to obtain the first proportional term parameter.

[0142] The second adjustment module 24 is used to adjust the second preset proportional term parameter according to the tension difference between the two hydraulic cylinders to obtain the second proportional term parameter, and to adjust the second preset integral term parameter according to the tension of each hydraulic cylinder and the difference between the corresponding second tension to obtain the second integral term parameter; the corresponding second tension is obtained based on the current oil pressure of the hydraulic cylinder inlet according to the preset correspondence between the oil pressure and the tension of each hydraulic cylinder inlet.

[0143] The third adjustment module 25 is used to adjust the opening of the proportional relief valve according to the first proportional term parameter, the first integral term parameter and the target total oil pressure of the next cycle, and to adjust the opening of the proportional directional valve according to the second proportional term parameter and the second integral term parameter; the target total oil pressure of the next cycle is determined according to the oil pressure compensation amount of each cycle and the current total oil pressure of the oil circuit.

[0144] Optionally, the first determining module 21 is further configured to:

[0145] The tension of the two hydraulic cylinders is obtained by a tension sensor, and the sum of the tension of the two hydraulic cylinders is determined as the total tension of the two hydraulic cylinders.

[0146] Obtain the main hydraulic pump outlet pressure in each cycle of each loading level to get the current total oil pressure of the oil circuit, and determine the corresponding first tension from the preset correspondence between the total oil pressure and tension of the loading level based on the current total oil pressure of the oil circuit.

[0147] The tension deviation for each cycle is obtained by comparing the total tension of the two hydraulic cylinders with the corresponding first tension within each cycle of each loading level.

[0148] For the system embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs.

[0149] Figure 3This is a schematic diagram of the structure of an electronic device according to an example embodiment of this application. The electronic device includes a memory, a processor, and a computer program stored in the memory and used to run on the processor. When the processor executes the computer program, it implements the method described in any of the above embodiments. Figure 3 The electronic device 30 shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0150] like Figure 3 As shown, the electronic device 30 can be manifested as a general-purpose computing device, such as a server device. The components of the electronic device 30 may include, but are not limited to: at least one processor 31, at least one memory 32, and a bus 33 connecting different system components (including memory 32 and processor 31).

[0151] Bus 33 includes a data bus, an address bus, and a control bus.

[0152] The memory 32 may include volatile memory, such as random access memory (RAM) 321 and / or cache memory 322, and may further include read-only memory (ROM) 323.

[0153] The memory 32 may also include a program tool 325 (or utility) having a set (at least one) program module 324, such program module 324 including but not limited to: an operating system, one or more application programs, other program modules and program data, each or some combination of these examples may include an implementation of a network environment.

[0154] The processor 31 executes various functional applications and data processing, such as the methods provided in any of the above embodiments, by running computer programs stored in the memory 32.

[0155] Electronic device 30 can also communicate with one or more external devices 34 (e.g., keyboard, pointing device, etc.). This communication can be performed via input / output (I / O) interface 35. Furthermore, electronic device 30 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public network, such as the Internet) via network adapter 36. As shown, network adapter 36 communicates with other modules of electronic device 30 via bus 33. It should be understood that, although not shown in the figure, other hardware and / or software modules can be used in conjunction with electronic device 30, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID (disk array) systems, tape drives, and data backup storage systems.

[0156] It should be noted that although several units / modules or sub-units / modules of the electronic device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, the features and functions of one unit / module described above can be further divided and embodied by multiple units / modules.

[0157] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method provided in any of the above embodiments.

[0158] The readable storage medium may be more specifically adopted, including but not limited to: portable disk, hard disk, random access memory, read-only memory, erasable programmable read-only memory, optical storage device, magnetic storage device, or any suitable combination thereof.

[0159] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0160] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the method described in any of the above embodiments.

[0161] The program code for executing the computer program product of this application can be written in any combination of one or more programming languages. The program code can be executed entirely on the user device, partially on the user device, as a standalone software package, partially on the user device and partially on a remote device, or entirely on a remote device.

[0162] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0163] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application.

[0164] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A hydraulic control method for a prestressed tensioning device, characterized in that, The method includes: The tension deviation for each cycle is determined based on the difference between the total tension of the two hydraulic cylinders and the corresponding first tension within each cycle of each loading level; the corresponding first tension is obtained based on the current total oil pressure in the oil circuit according to the preset correspondence between the total oil pressure and the tension for that loading level. The oil pressure compensation for a given cycle is obtained by taking the tension deviation for each cycle at each loading level, the sum of the tension deviations for multiple cycles within that loading level, and the difference between the tension deviation for that cycle and the tension deviation for the previous cycle. The first preset integral term parameter is obtained by adjusting the sum of the tensile deviations of multiple cycles within each loading level. The first preset proportional term parameter is obtained by adjusting the difference between the tensile deviation of each cycle and the tensile deviation of the previous cycle. The second preset proportional term parameter is adjusted according to the difference in pulling force between the two hydraulic cylinders to obtain the second proportional term parameter. The second preset integral term parameter is adjusted according to the difference between the pulling force of each hydraulic cylinder and the corresponding second pulling force to obtain the second integral term parameter. The corresponding second pulling force is obtained based on the current oil pressure at the oil inlet of each hydraulic cylinder, according to the preset correspondence between the oil pressure and the pulling force at the oil inlet of that hydraulic cylinder. The opening of the proportional relief valve is adjusted according to the first proportional term parameter, the first integral term parameter, and the target total oil pressure for the next cycle; the opening of the proportional directional valve is adjusted according to the second proportional term parameter and the second integral term parameter; the target total oil pressure for the next cycle is determined based on the oil pressure compensation amount for each cycle and the current total oil pressure in the oil circuit. The determination of the tension deviation for each cycle based on the difference between the total tension of the two hydraulic cylinders and the corresponding first tension within each cycle of each loading level includes: The tension of the two hydraulic cylinders is obtained by a tension sensor, and the sum of the tension of the two hydraulic cylinders is determined as the total tension of the two hydraulic cylinders. Obtain the main hydraulic pump outlet pressure in each cycle of each loading level to get the current total oil pressure of the oil circuit, and determine the corresponding first tension from the preset correspondence between the total oil pressure and tension of the loading level based on the current total oil pressure of the oil circuit. The tension deviation for each cycle is obtained by comparing the total tension of the two hydraulic cylinders with the corresponding first tension within each cycle of each loading level. The method of obtaining the hydraulic pressure compensation amount for a given cycle based on the tension deviation of each cycle at each loading level, the sum of the tension deviations across multiple cycles within that loading level, and the difference between the tension deviation of that cycle and the tension deviation of the previous cycle includes: Calculate the tensile deviation for each cycle and the sum of the tensile deviations for multiple cycles preceding that cycle within the same loading level to obtain the integral value of the tensile deviation for that cycle at that loading level. The differential value of the tensile deviation for each cycle within each loading level is obtained by comparing the tensile deviation of the previous cycle with the tensile deviation of the previous cycle. The oil pressure compensation amount for each cycle is determined by the ratio of the integral value of the tension deviation in each cycle to the number of cycles in the same loading level and the number of cycles before that cycle, the ratio of the differential value of the tension deviation in that cycle to the first tension corresponding to that cycle, and the current total oil pressure in the oil circuit.

2. The hydraulic control method for a prestressed tensioning device as described in claim 1, characterized in that, The first integral term parameter is obtained by adjusting the first preset integral term parameter based on the sum of the tensile deviations of multiple cycles within each loading level, and the first proportional term parameter is obtained by adjusting the first preset proportional term parameter based on the difference between the tensile deviation of each cycle and the tensile deviation of the previous cycle, including: The first preset integral term parameter is obtained by adjusting the product of the differential value of the tension deviation in each cycle and the preset value. The first proportional term parameter is obtained by adjusting the product of the integral value of the tension deviation in each cycle and the preset value.

3. The hydraulic control method for a prestressed tensioning device as described in claim 1, characterized in that, The process of adjusting the second preset proportional term parameter based on the force difference between the two hydraulic cylinders to obtain the second proportional term parameter, and adjusting the second preset integral term parameter based on the force of each hydraulic cylinder and the corresponding second force difference to obtain the second integral term parameter, includes: The tension of the two hydraulic cylinders is obtained by using a tension sensor, and the difference between the tensions of the two hydraulic cylinders is calculated to obtain the tension difference between the two hydraulic cylinders. The second preset proportional parameter is adjusted according to the difference in pulling force between the two hydraulic cylinders to obtain the adjusted second proportional parameter. Based on the current oil pressure at the inlet of each hydraulic cylinder, the second tension corresponding to the hydraulic cylinder is determined from the preset correspondence between the oil pressure and tension at the inlet of the hydraulic cylinder, and the difference between the tension of each hydraulic cylinder and the corresponding second tension in each cycle is calculated to obtain the tension difference value of the hydraulic cylinder in that cycle. The tension error integral of a hydraulic cylinder is determined by summing the tension difference of each hydraulic cylinder in each cycle with the tension differences of multiple cycles preceding that cycle within the same loading level. The second preset integral term parameter is obtained by adjusting the second integral term parameter based on the difference in the integral of the tension error between the two hydraulic cylinders.

4. The hydraulic control method for a prestressed tensioning device as described in claim 3, characterized in that, The step of adjusting the opening of the proportional directional valve according to the second proportional term parameter and the second integral term parameter includes: The first preset differential parameter is adjusted based on the difference between the tension difference of each hydraulic cylinder in each cycle and the tension difference in the previous cycle, the difference between the integral of the tension error of the two hydraulic cylinders in this cycle, and the difference between the integral of the tension error of the two hydraulic cylinders in the previous cycle, to obtain the first differential parameter. The opening degree of the proportional directional valve is adjusted according to the second proportional term parameter, the second integral term parameter, and the first derivative parameter.

5. The hydraulic control method for a prestressed tensioning device as described in claim 1, characterized in that, Before adjusting the opening of the proportional relief valve based on the first proportional term parameter, the first integral term parameter, and the target total oil pressure for the next cycle, the method further includes: Based on the current total oil pressure of the oil circuit in each cycle of each loading level, the total oil pressure of the oil circuit in the next cycle is determined from the preset correspondence between the total oil pressure of the oil circuit in that loading level and the loading duration. The target total oil pressure for the next cycle is determined based on the oil pressure compensation amount for each cycle at each loading level and the total oil pressure in the oil circuit for the next cycle.

6. The hydraulic control method for a prestressed tensioning device as described in claim 5, characterized in that, The step of adjusting the opening of the proportional relief valve according to the first proportional term parameter, the first integral term parameter, and the target total oil pressure for the next cycle includes: The first proportional term parameter is adjusted based on the difference between the target total oil pressure for the next cycle and the current total oil pressure in the oil circuit for that cycle, to obtain the adjusted first proportional term parameter. Based on the loading duration corresponding to each cycle of each loading level, the target oil pressure for that cycle is determined from the preset correspondence between the total oil pressure and the loading duration of the oil circuit for that loading level. The first integral term parameter is adjusted based on the difference between the target oil pressure for each cycle and the current total oil pressure in the oil circuit for that cycle, resulting in the adjusted first integral term parameter. The preset second differential parameter is adjusted based on the difference between the target oil pressure and the starting oil pressure of each cycle, and the difference between the current total oil pressure of the oil circuit and the starting oil pressure of the cycle, to obtain the adjusted second differential parameter; the starting oil pressure of each cycle is the target oil pressure of the previous cycle. The opening degree of the proportional relief valve is adjusted according to the adjusted first proportional term parameter, the adjusted first integral term parameter, and the adjusted second derivative parameter.

7. A hydraulic control system for a prestressed tensioning device, characterized in that, The system is used to implement the hydraulic control method for a prestressed tensioning device according to any one of claims 1-6, the system comprising: The first determining module is used to determine the tension deviation in each cycle based on the difference between the total tension of the two hydraulic cylinders and the corresponding first tension in each cycle of each loading level; the corresponding first tension is obtained based on the current total oil pressure of the oil circuit according to the preset correspondence between the total oil pressure and the tension in the loading level. The second determining module is used to obtain the oil pressure compensation amount for the current cycle based on the tension deviation amount for each cycle of each loading level, the sum of the tension deviation amounts for multiple cycles within the loading level, and the difference between the tension deviation amount for the current cycle and the tension deviation amount for the previous cycle. The first adjustment module is used to adjust the first preset integral term parameter according to the sum of the tensile deviations of multiple cycles within each loading level to obtain the first integral term parameter, and to adjust the first preset proportional term parameter according to the difference between the tensile deviation of each cycle and the tensile deviation of the previous cycle to obtain the first proportional term parameter. The second adjustment module is used to adjust the second preset proportional term parameter according to the tension difference between the two hydraulic cylinders to obtain the second proportional term parameter, and to adjust the second preset integral term parameter according to the tension of each hydraulic cylinder and the difference between the corresponding second tension to obtain the second integral term parameter; the corresponding second tension is obtained based on the current oil pressure of the hydraulic cylinder inlet according to the preset correspondence between the oil pressure and the tension at the oil inlet of each hydraulic cylinder. The third adjustment module is used to adjust the opening of the proportional relief valve according to the first proportional term parameter, the first integral term parameter and the target total oil pressure of the next cycle, and to adjust the opening of the proportional directional valve according to the second proportional term parameter and the second integral term parameter; the target total oil pressure of the next cycle is determined according to the oil pressure compensation amount of each cycle and the current total oil pressure of the oil circuit. The first determining module is further configured to: The tension of the two hydraulic cylinders is obtained by a tension sensor, and the sum of the tension of the two hydraulic cylinders is determined as the total tension of the two hydraulic cylinders. Obtain the main hydraulic pump outlet pressure in each cycle of each loading level to get the current total oil pressure of the oil circuit, and determine the corresponding first tension from the preset correspondence between the total oil pressure and tension of the loading level based on the current total oil pressure of the oil circuit. The tension deviation for each cycle is obtained by comparing the total tension of the two hydraulic cylinders with the corresponding first tension within each cycle of each loading level. The hydraulic pressure compensation for a given cycle is obtained based on the tension deviation for each cycle at each loading level, the sum of the tension deviations across multiple cycles within that loading level, and the difference between the tension deviation for that cycle and the tension deviation for the previous cycle. This includes: Calculate the tensile deviation for each cycle and the sum of the tensile deviations for multiple cycles preceding that cycle within the same loading level to obtain the integral value of the tensile deviation for that cycle at that loading level. The differential value of the tensile deviation for each cycle within each loading level is obtained by comparing the tensile deviation of the previous cycle with the tensile deviation of the previous cycle. The oil pressure compensation amount for each cycle is determined by the ratio of the integral value of the tension deviation in each cycle to the number of cycles in the same loading level and the number of cycles before that cycle, the ratio of the differential value of the tension deviation in that cycle to the first tension corresponding to that cycle, and the current total oil pressure in the oil circuit.

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