Multi-cylinder synchronous control method and system for internal formwork hydraulic system used in bridge construction

Abstract

This invention relates to the field of bridge construction technology, specifically to a multi-cylinder synchronous control method and system for an internal formwork hydraulic system used in bridge construction. It includes: acquiring cylinder pressure and displacement data; calculating the initial opening of the proportional servo valve of each slave cylinder based on the displacement difference between the master and slave cylinders; determining whether the initial opening needs correction based on the slave cylinder pressure, and if so, calculating the corrected opening; determining whether feedforward compensation is needed based on the pressure difference between each slave and master cylinder, and if so, calculating the compensated opening; calculating the final opening of the proportional servo valve of each slave cylinder based on the reference opening of the master cylinder proportional servo valve and the compensated and corrected openings of the slave cylinder proportional servo valves; and adjusting the opening of the slave cylinder proportional servo valves. This application comprehensively utilizes PID control, pressure correction, and feedforward compensation technologies, and has significant advantages such as precise synchronization, balanced force, high safety, and strong adaptability.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, specifically to a multi-cylinder synchronous control method and system for an internal formwork hydraulic system used in bridge construction. Background Technology

[0002] In bridge construction, the opening and closing of the inner mold is a crucial step in the casting and handling of precast beams. In existing technologies, the inner mold is driven collaboratively by multiple hydraulic cylinders, with opening and closing achieved through manual operation or PLC sequential control. For example, Chinese invention patent CN108087349A, entitled "A Hydraulic Cylinder Servo Synchronous Control System," provides a hydraulic cylinder servo synchronous control system. This system includes an array of hydraulic cylinders, each equipped with an individual servo motor to control its cylinder pressure. The piston end of each hydraulic cylinder is equipped with a displacement detection grating, the output of which is connected to a high-speed counting module. The output of the high-speed counting module is connected to a main controller, which controls the speed of the servo drive motor through a digital-to-analog converter (D / A) module. This system uses a programmable logic controller (PLC) as the main controller, combined with PID control technology. By controlling the output magnitude of the analog signal through PID control, it achieves precise control of the servo motor speed, thereby controlling the operating speed of the hydraulic cylinders. This system is suitable for precise control of the speed and displacement synchronization of hydraulic pump-driven cylinders that rotate in both directions.

[0003] However, the adjustment data from the shaft in this system undergoes multiple conversions, resulting in a lag. When applied to the inner formwork closing stage in bridge construction, factors such as the nonlinearity of the hydraulic system and manufacturing errors of the cylinders often cause asynchronous phenomena during formwork closing. This leads to excessive local stress on the formwork, stroke stagnation, loose joints in the beam, and local high-pressure impacts on the hydraulic system, resulting in incomplete formwork closing and mold deformation. These issues affect the quality of the finished beam and increase construction safety risks. Summary of the Invention

[0004] The purpose of this application is to address the shortcomings of the aforementioned background technology and to provide a multi-cylinder synchronous control method and system for an internal mold hydraulic system used in bridge construction.

[0005] The technical solution of this application is: a multi-cylinder synchronous control method for an internal formwork hydraulic system used in bridge construction, comprising: Based on the position of the hydraulic cylinder or the stability of the load, select one hydraulic cylinder as the master cylinder and the remaining hydraulic cylinders as slave cylinders. Collect the displacement of the master cylinder piston rod, the displacement of the slave cylinder piston rod, and the pressure of the master cylinder and the slave cylinder. The initial opening of the slave cylinder proportional servo valve is calculated based on the displacement difference between each slave cylinder and the master cylinder. The initial opening of the slave cylinder proportional servo valve needs to be corrected based on the slave cylinder pressure. If correction is needed, the corrected opening of the slave cylinder proportional servo valve is calculated. Based on the pressure difference between each slave cylinder and the master cylinder, determine whether feedforward compensation is needed for the opening of the slave cylinder proportional servo valve. If feedforward compensation is needed, calculate the compensation opening of the slave cylinder proportional servo valve. The final opening of the slave cylinder proportional servo valve is calculated based on the reference opening of the master cylinder proportional servo valve and the compensation and correction opening of the slave cylinder proportional servo valve. The opening degree of the slave cylinder proportional servo valve is adjusted based on the calculated final opening degree of the slave cylinder proportional servo valve.

[0006] According to the multi-cylinder synchronous control method for an internal mold hydraulic system for bridge construction provided in this application, the method for calculating the initial opening of the proportional servo valve of the slave cylinder based on the displacement difference between each slave cylinder and the master cylinder includes: calculating the initial opening of the proportional servo valve of the slave cylinder according to the following formula. + in: —The initial opening degree of the i-th slave cylinder proportional servo valve; —The displacement difference between the i-th slave cylinder and the master cylinder; K p —First displacement proportionality coefficient; K i —Second displacement proportionality coefficient; K d —Third displacement proportionality coefficient.

[0007] According to the multi-cylinder synchronous control method of the internal mold hydraulic system for bridge construction provided in this application, the method for determining whether the initial opening of the slave cylinder proportional servo valve needs to be corrected based on the slave cylinder pressure includes: if the ratio of the difference between the warning value and the slave cylinder pressure to the warning value is less than a set value, then it is determined that correction is needed; otherwise, no correction is needed; the warning value is less than the maximum allowable working pressure of the slave cylinder.

[0008] According to the multi-cylinder synchronous control method for an internal mold hydraulic system for bridge construction provided in this application, the method for calculating the corrected opening of the slave cylinder proportional servo valve includes: calculating the corrected opening of the slave cylinder proportional servo valve according to the following formula. in: —The corrected opening degree of the i-th slave cylinder proportional servo valve; —The initial opening degree of the i-th slave cylinder proportional servo valve; —The pressure scaling factor of the i-th cylinder; Calculate the pressure scaling factor using the following formula.

[0009] in: —Lower limit of pressure scaling factor; —The pressure of the i-th cylinder; —Warning value; —From the cylinder's maximum permissible working pressure; — Pressure scaling sensitivity coefficient.

[0010] According to the multi-cylinder synchronous control method of the internal mold hydraulic system for bridge construction provided in this application, the method of determining whether feedforward compensation is needed for the opening degree of the proportional servo valve of the slave cylinder based on the pressure difference between each slave cylinder and the master cylinder includes: calculating the pressure difference between each slave cylinder and the master cylinder; if the pressure difference is greater than a set pressure difference threshold, it is determined that feedforward compensation is needed for the opening degree of the proportional servo valve of the slave cylinder; otherwise, feedforward compensation is not needed for the opening degree of the proportional servo valve of the slave cylinder.

[0011] According to the multi-cylinder synchronous control method for an internal mold hydraulic system for bridge construction provided in this application, the method for calculating the compensation opening of the slave cylinder proportional servo valve includes: calculating the compensation opening of the slave cylinder proportional servo valve according to the following formula. in: —The compensation opening degree of the i-th slave cylinder proportional servo valve; —The pressure difference between the i-th slave cylinder and the master cylinder; —Feedforward compensation ratio coefficient.

[0012] According to the multi-cylinder synchronous control method for an internal mold hydraulic system used in bridge construction provided in this application, the method for calculating the final opening degree of the slave cylinder proportional servo valve includes: calculating the final opening degree of the slave cylinder proportional servo valve according to the following formula. in: —The final opening degree of the i-th slave cylinder proportional servo valve; —The corrected opening degree of the i-th slave cylinder proportional servo valve; —The reference opening degree of the main cylinder proportional servo valve; —The compensation opening degree of the i-th slave cylinder proportional servo valve.

[0013] According to the multi-cylinder synchronous control method of the internal formwork hydraulic system for bridge construction provided in this application, the displacement of the slave cylinder piston rod is compared with the preset upper limit of displacement, and the slave cylinder pressure is compared with the preset upper limit of pressure. If the displacement of the slave cylinder piston rod exceeds the preset upper limit of displacement or the slave cylinder pressure exceeds the preset upper limit of pressure, the proportional servo valve signal of the slave cylinder is cut off, the pump station outlet valve is closed, and an emergency stop protection strategy is executed.

[0014] According to the multi-cylinder synchronous control method of the hydraulic system for internal mold in bridge construction provided in this application, the pressure difference between two adjacent sets of oil cylinders at the installation position is compared with the set tolerance. If the pressure difference between two adjacent sets of oil cylinders exceeds the set tolerance, an audible and visual alarm is triggered, and the opening of the proportional servo valve of the oil cylinder is controlled to reduce the action speed of the oil cylinder.

[0015] According to the multi-cylinder synchronous control method of the hydraulic system for internal mold in bridge construction provided in this application, the pressure change value of the cylinder per unit time and the displacement change value of the cylinder piston rod are calculated. If the pressure change value exceeds the first change threshold or the displacement change value exceeds the second change threshold, it is determined that the cylinder has a potential risk and an audible and visual alarm is triggered.

[0016] This application also relates to a multi-cylinder synchronous control system for an internal mold hydraulic system used in bridge construction. The control system operates according to the aforementioned multi-cylinder synchronous control method for an internal mold hydraulic system used in bridge construction, including... A master-slave definition module is used to select one cylinder from multiple cylinders as the master cylinder and the remaining cylinders as slave cylinders. The data acquisition module is used to acquire the displacement of the master cylinder piston rod, the displacement of the slave cylinder piston rod, and the pressure of the master cylinder and the pressure of the slave cylinder; An initial opening calculation module calculates the initial opening of the slave cylinder proportional servo valve based on the displacement difference between each slave cylinder and the master cylinder. The correction judgment module determines whether the initial opening of the slave cylinder proportional servo valve needs to be corrected based on the slave cylinder pressure. The correction calculation module calculates the corrected opening of the slave cylinder proportional servo valve when it determines that the initial opening of the slave cylinder proportional servo valve needs to be corrected. The compensation judgment module determines whether feedforward compensation is needed for the opening of the proportional servo valve of the slave cylinder based on the pressure difference between each slave cylinder and the master cylinder. The compensation calculation module calculates the compensation opening of the slave cylinder proportional servo valve when it determines that feedforward compensation is needed for the opening of the slave cylinder proportional servo valve. The final opening calculation module calculates the final opening of the slave cylinder proportional servo valve based on the reference opening of the master cylinder proportional servo valve and the compensated opening and corrected opening of the slave cylinder proportional servo valve. The adjustment execution module adjusts the opening of the slave cylinder proportional servo valve based on the calculated final opening of the slave cylinder proportional servo valve.

[0017] The advantages of this application are as follows: 1. The control method of this application uses the master cylinder as a reference to perform closed-loop adjustment of the slave cylinder. By collecting displacement and pressure data in real time, the synchronization of multiple cylinders during the movement process is ensured, guaranteeing the precise synchronization of the opening and closing of the inner mold, and avoiding template jamming, deformation, or decline in bridge construction quality caused by asynchrony; through judgment and correction based on pressure difference, the system can dynamically adjust the opening of the slave cylinder, so that each cylinder is subjected to uniform force, reducing local stress concentration, preventing hydraulic system overload or template damage, and extending the service life of the equipment; the feedforward compensation mechanism can adjust the slave cylinder in advance to avoid safety problems caused by sudden pressure changes or load changes, such as hydraulic shock, cylinder runaway, or template collision; by automatically judging whether correction and feedforward compensation are needed based on real-time data, intelligent adaptive adjustment is realized, reducing manual intervention, improving control efficiency and response speed, and is suitable for complex and ever-changing bridge construction environments; 2. The PID control algorithm of this application achieves precise adjustment of the slave cylinder position by rapidly responding to displacement difference with the proportional term, eliminating steady-state error with the integral term, and predicting change trends with the derivative term. This ensures that the cylinder displacement closely tracks the master cylinder, improving the accuracy and smoothness of synchronous control. The PID parameters are adjustable, allowing the system to be optimized according to actual working conditions (such as load changes or cylinder characteristics), ensuring stable operation under various conditions. The algorithm is insensitive to changes in system parameters, enhancing the robustness of the system and making it suitable for vibrations and load fluctuations commonly encountered in construction. The introduction of the derivative term enables the system to compensate for displacement change trends in advance, reducing overshoot and oscillation, thereby accelerating the system response speed and making the opening and closing action of the inner mold smoother. 3. By setting a warning value (less than the maximum allowable working pressure of the slave cylinder) and a set value, this application enables the system to detect in a timely manner whether the slave cylinder pressure is approaching a dangerous level and trigger a correction mechanism, preventing cylinder overload, protecting hydraulic components from damage, and improving construction safety. This method has active safety characteristics, avoiding failures caused by pressure exceeding limits. Using a ratio comparison (the ratio of the difference between the warning value and the slave cylinder pressure to the warning value), rather than an absolute pressure value, makes the judgment conditions more sensitive and accurate, reduces the risk of misjudgment, ensures that the correction mechanism is activated only when necessary, avoids unnecessary adjustments, and improves system efficiency. 4. The pressure scaling factor of this application dynamically adjusts the initial opening, making the correction process smooth and gradual, avoiding hydraulic shock or system oscillation caused by sudden changes in opening. The lower limit value in the formula prevents control failure caused by excessively small opening, ensuring the reliability of the adjustment. The sensitivity coefficient allows adjustment of the intensity of pressure scaling, enabling the system to be optimized according to specific application requirements. This adjustability makes the method adaptable to different hydraulic systems and construction conditions, improving its versatility. By calculating the scaling factor by the ratio of real-time pressure to the warning value, the system can adaptively reduce the opening to alleviate pressure, thereby automatically "decelerating" when the pressure approaches the danger value, ensuring that the cylinder operates within a safe range and extending the equipment life. 5. By directly comparing the pressure difference with a threshold, the system can quickly detect uneven load or external disturbances and immediately trigger feedforward compensation, avoiding the accumulation of synchronization errors and improving the dynamic response capability of the system. Feedforward compensation is a forward-looking control strategy that can make adjustments before problems (such as pressure imbalance) occur, thereby preventing synchronization loss of control, reducing adjustment delay, and ensuring the continuity and accuracy of the inner mold action. It is suitable for scenarios in construction that require high synchronization accuracy. 6. The compensation opening degree of this application is proportional to the pressure difference. It can be linearly adjusted by a coefficient to accurately compensate for pressure differences, restore the force balance between cylinders, simplify the calculation process, improve real-time performance, and is suitable for high-speed control hydraulic systems. The formula structure is simple and the calculation burden is small, which enables the system to quickly generate compensation signals, reduces processing delay, enhances the real-time performance of the system, and ensures synchronization in dynamic environments. 7. The final opening degree of this application integrates three factors: reference, correction, and compensation, realizing multi-parameter coordinated control. This ensures that the slave cylinder not only tracks the displacement of the master cylinder but also considers pressure balance and safety correction, improving the overall control accuracy and robustness. Using the master cylinder reference opening degree as a reference, it ensures coordinated movement between the slave cylinder and the master cylinder. The corrected opening degree handles the risk of pressure overload, and the compensated opening degree addresses pressure differences. This integrated method enables the system to handle complex working conditions, such as sudden load changes or multi-cylinder interaction, ensuring the smoothness and reliability of the inner mold opening and closing. 8. By comparing displacement and pressure with the upper limit value in real time, the system can detect abnormalities (such as hydraulic shock or formwork overload) in a timely manner and immediately execute emergency stop measures to prevent equipment damage, hydraulic leakage or formwork collision, and significantly improve construction safety. The emergency stop strategy does not require manual intervention. The system automatically cuts off signals and valves, ensuring fast and reliable protection, reducing operational risks, and is particularly suitable for high-risk environments during construction. 9. By monitoring the pressure difference between adjacent cylinders, the system can detect synchronization deviations or uneven loads at an early stage and alert operators with audible and visual alarms, allowing for timely intervention and preventing minor problems from escalating into serious malfunctions. At the same time as the alarm, the system reduces the cylinder's operating speed, avoiding the impact caused by sudden stops, enabling the system to smoothly transition to a safe state, reducing hydraulic shock and mechanical stress, protecting the cylinders and templates, and improving the system's reliability and user experience. 10. By monitoring pressure and displacement changes, the system can identify abnormal patterns in the hydraulic cylinder, such as wear, leakage, or jamming, thus providing early warnings. Early detection of potential faults allows for planned maintenance, extending equipment life and reducing maintenance costs. It also enhances the reliability and availability of the entire hydraulic system, making it suitable for long-term bridge construction projects where equipment continuity is crucial. 11. The system of this application consists of dedicated modules with a clear structure, making it easy to implement, test, and maintain. Each module is responsible for a specific function (such as data acquisition and calculation), improving code readability and system scalability. It allows for module customization or upgrades based on actual needs, adapting to different bridge construction scenarios. The system automates the entire control process, from data acquisition to valve opening adjustment, reducing manual operation and improving construction efficiency and accuracy. By integrating all the advantages of the method claims, the system ensures the synchronization, safety, and reliability of the internal mold hydraulic system. The system modules work collaboratively, achieving comprehensive optimization of multi-cylinder synchronous control, including real-time monitoring, intelligent judgment, and rapid execution. This improves the overall quality of bridge construction and reduces engineering risks.

[0018] This application utilizes a multi-cylinder synchronous control method and system, which comprehensively applies technologies such as PID control, pressure correction, feedforward compensation, safety protection, and fault prediction. It has significant advantages such as precise synchronization, balanced force, high safety, and strong adaptability. Attached Figure Description

[0019] Figure 1 : A flowchart illustrating the control method of this application. Detailed Implementation

[0020] The embodiments of this application are described in detail below, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0021] In the description of this application, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0023] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] This application relates to a multi-cylinder synchronous control method for an internal formwork hydraulic system used in bridge construction. The control method of this application is used to solve problems such as asynchronous operation of hydraulic cylinders during mold closing, uneven force on the formwork, stroke jamming, and hydraulic system impact.

[0025] Specifically, this application discloses a multi-cylinder synchronous control method for an internal formwork hydraulic system used in bridge construction, such as... Figure 1 As shown, follow these steps: S1. Among the multiple cylinders in the control system, select one as the master cylinder according to a preset strategy (such as the cylinder located in the center or the cylinder with the most stable load, or the cylinder that is at the forefront along the bridge during bridge construction), and define the rest as slave cylinders. S2. The displacement of the master cylinder piston rod is collected in real time by a displacement sensor, and the displacement of each slave cylinder piston rod is also collected in real time by a pressure sensor; the pressure of the master cylinder and the pressure of each slave cylinder are collected in real time by a pressure sensor. S3. Based on the real-time displacement difference between each slave cylinder and the master cylinder, calculate the initial opening of the proportional servo valve of the slave cylinder. S4. Based on the collected cylinder pressure, determine whether the initial opening calculated in step S3 needs to be corrected. If so, proceed to step S5. S5. Calculate the corrected opening degree of the proportional servo valve of the slave cylinder; S6. Based on the real-time pressure difference between each slave cylinder and the master cylinder, determine whether feedforward compensation is needed for the opening of the slave cylinder proportional servo valve. If so, proceed to step S7. S7. Calculate the compensation opening of the proportional servo valve of the slave cylinder; S8. Combine the reference opening of the master cylinder proportional servo valve with the calculated corrected opening and compensation opening of the slave cylinder proportional servo valve to calculate the final opening of the slave cylinder proportional servo valve. S9. Output the final opening signal to the corresponding slave cylinder proportional servo valve to drive its action and achieve precise control of the slave cylinder.

[0026] The control method of this application uses the motion of the master cylinder as the ideal reference trajectory. It ensures the tracking accuracy of the slave cylinder to the master cylinder through displacement closed-loop (feedback control) to achieve synchronization; it ensures the force balance of each cylinder through pressure monitoring and correction (feedback adjustment) to prevent overload; and it responds to sudden load changes in advance through pressure difference feedforward compensation (feedforward control) to improve the dynamic response speed and anti-interference capability of the system.

[0027] The control method of this application achieves high-precision synchronous movement of multiple cylinders during the opening and closing of the inner mold, effectively avoiding problems such as mold jamming and uneven internal stress of components caused by asynchrony. At the same time, by introducing pressure correction and feedforward compensation, the stability and safety of the system are significantly improved, enabling it to adapt to complex load changes in bridge construction and ensuring construction quality and efficiency.

[0028] In some embodiments of this application, step S3 described above has been optimized. Specifically, the method for calculating the initial opening of the slave cylinder proportional servo valve based on the displacement difference between each slave cylinder and the master cylinder includes: calculating the initial opening of the slave cylinder proportional servo valve according to the following formula. + in: —The initial opening degree of the i-th slave cylinder proportional servo valve; —The displacement difference between the i-th slave cylinder and the master cylinder; K p —First displacement proportionality coefficient; K i —Second displacement proportionality coefficient; K d —Third displacement proportionality coefficient.

[0029] The above formula is a PID controller algorithm. The proportional term responds immediately to the displacement difference; the integral term accumulates historical errors to eliminate static errors and ensure that the slave cylinder can eventually be perfectly aligned with the master cylinder; the derivative term makes predictive adjustments based on the error change rate, which can suppress oscillations and make the synchronization process smoother.

[0030] coefficients in the above formula Kp 、K i 、K d It needs to be obtained based on the specific characteristics of the hydraulic system, for example, through the Ziegler-Nichols method or experimental trial and error.

[0031] This embodiment uses a PID algorithm to calculate the initial opening, which has a simple structure, high reliability, and good control accuracy. It can quickly respond to displacement deviations and completely eliminate synchronization errors through integral action, while derivative action effectively improves the dynamic quality of the system, making the cylinder's following action both rapid and smooth, laying a solid foundation for achieving high-precision synchronization.

[0032] In other embodiments of this application, step S4 described above has been optimized. Specifically, the method for determining whether the initial opening of the slave cylinder proportional servo valve needs to be corrected based on the slave cylinder pressure includes: setting a pressure warning value. p warn This value is less than the maximum allowable working pressure of the cylinder. p max For example, set as a pressure warning value p warn For the maximum allowable working pressure of the cylinder p max 80% to 90%. Then, calculate. (p warn -p i (t)) / p warn The value of , where p i (t) This represents the real-time pressure of the i-th slave cylinder. If this ratio is less than a set value... α (The value ranges from 0.05 to 0.2, for example) α If the value is 0.1 (i.e., 10%), then a correction is needed; otherwise, no correction is needed.

[0033] The essence of the judgment logic in this embodiment is to monitor whether the cylinder pressure is close to the warning level. When p i (t) Increase, making (p warn -p i (t)) The value decreases, and it is related to the pressure warning value. p warn The ratio also decreases. When this ratio is lower than the set threshold α, it indicates that the cylinder pressure has risen to near the warning value, posing an overload risk. The load must be reduced by adjusting the valve opening to prevent the pressure from continuing to rise.

[0034] In each control cycle, the system calculates the initial opening degree. ui''(t) Then, this judgment logic will be executed in parallel. If the judgment result indicates that correction is needed, the correction calculation module will be triggered; otherwise, the initial opening degree will be used directly for subsequent calculations.

[0035] This embodiment provides a simple yet effective overload early warning mechanism that intervenes proactively, preventing problems before they occur, rather than only triggering when the pressure reaches its limit. By setting reasonable warning values ​​and ratio thresholds, sensitive and accurate correction triggering can be achieved, avoiding false triggering caused by pressure sensor fluctuations and ensuring that the system operates within a safe pressure range.

[0036] In a further embodiment of this application, step S5 described above is optimized. Specifically, the method for calculating the corrected opening degree of the slave cylinder proportional servo valve includes: calculating the corrected opening degree of the slave cylinder proportional servo valve according to the following formula. in: —The corrected opening degree of the i-th slave cylinder proportional servo valve; —The initial opening degree of the i-th slave cylinder proportional servo valve; —The pressure scaling factor of the i-th cylinder; Calculate the pressure scaling factor using the following formula.

[0037] in: —Lower limit of pressure scaling factor; —The pressure of the i-th cylinder; —Warning value; —From the cylinder's maximum permissible working pressure; — Pressure scaling sensitivity coefficient.

[0038] This embodiment uses a dynamic scaling factor. s(p i ) To adjust the initial opening. When the cylinder pressure p i (t) Below the warning value p warn hour, s(p i ) ≈1, the corrected opening is equal to the initial opening, with no impact. When the pressure exceeds the warning value, s(p i ) The pressure scaling factor initially decreases linearly from 1, proportionally reducing the valve opening and decreasing the flow rate into the cylinder, thus slowing its velocity and lowering the pressure. (Lower limit of pressure scaling factor) s min This ensured the continuity of control.

[0039] Once a correction is determined to be necessary, the system calls this formula to calculate the corresponding pressure in real time. s(p i ) Then, the initial opening is scaled to obtain the corrected opening. .

[0040] The correction method in this embodiment achieves smooth, adaptive pressure release. Instead of simply cutting off the signal, it adjusts gradually, avoiding hydraulic shocks and system oscillations caused by sudden stops. This is achieved through the pressure scaling sensitivity coefficient γ and the lower limit of the pressure scaling factor. s min The adjustable design allows the method to be flexibly adapted to different specifications of hydraulic systems and cylinders, optimize the control effect, and maximize the system's ability to continue working while ensuring safety.

[0041] In some embodiments of this application, this embodiment optimizes the above-mentioned step S6. This embodiment specifically describes step S6 in claim 1, namely, the method of determining whether feedforward compensation is needed based on pressure difference.

[0042] Methods for determining whether feedforward compensation is needed for the opening of the proportional servo valve in each slave cylinder based on the pressure difference between each slave cylinder and the master cylinder include: real-time calculation of the pressure difference between each slave cylinder and the master cylinder. Δp i (t)= p m (t)- p i (t) ,in p m (t) Main cylinder pressure. Establish a set pressure difference threshold. Δp set .like |Δp i (t)|>Δp set If the opening of the i-th slave cylinder proportional servo valve is positive, then feedforward compensation is required; otherwise, it is not required.

[0043] The pressure difference between each cylinder directly reflects the degree of uneven load distribution. When the absolute value of the pressure difference between a slave cylinder and the master cylinder exceeds the set pressure difference threshold, it indicates that the load borne by the slave cylinder is significantly different from that of the master cylinder. If this difference is not corrected in time, it will quickly turn into displacement asynchrony, and may even lead to cylinder "pressure buildup" or "empty space". Feedforward compensation intervenes in advance when this asynchrony trend just appears.

[0044] During actual control, the system will compare the pressure difference calculated in real time with the set pressure difference threshold. Δp set In comparison, once the limit is exceeded, feedforward compensation calculation is immediately triggered.

[0045] This embodiment's judgment logic does not rely on the occurrence of displacement error, but rather acts proactively by monitoring the precursor signal of force imbalance. This greatly improves the system's response speed and effectively suppresses synchronization misalignment caused by sudden load changes, which is key to achieving high dynamic performance synchronization.

[0046] In a further embodiment of this application, the above-described feedforward compensation calculation is optimized. Specifically, the method for calculating the compensation opening of the slave cylinder proportional servo valve includes: calculating the compensation opening of the slave cylinder proportional servo valve according to the following formula. in: —The compensation opening degree of the i-th slave cylinder proportional servo valve; —The pressure difference between the i-th slave cylinder and the master cylinder; —The feedforward compensation ratio coefficient can be positive or negative, depending on the cylinder connection method (for example, if the pressure difference is positive, it means that the cylinder is overloaded, so a positive opening compensation should be given to speed up its action to share the load).

[0047] The above formula actually constructs a typical proportional feedforward controller, generating an additional control signal proportional to the pressure difference, which is directly superimposed on the main control signal. When a pressure difference is detected, the system immediately predicts how much valve opening change is needed to offset this load difference and outputs that signal directly, instead of waiting for displacement errors to appear and then slowly adjusting.

[0048] In actual control, after determining that feedforward compensation is needed, the system calls this formula, multiplying the real-time pressure difference by the feedforward compensation ratio coefficient. K f The compensated opening of the i-th slave cylinder proportional servo valve is obtained instantaneously. u f (t) .

[0049] This embodiment employs a simple and direct feedforward compensation calculation with extremely fast response speed and virtually no delay. It can proactively eliminate the effects of uneven load, enabling the system to maintain excellent synchronization performance even when facing external disturbances. This significantly reduces the burden on displacement closed-loop control, making the entire system more stable and robust.

[0050] In other embodiments of this application, step S8 described above has been optimized. Specifically, the method for calculating the final opening degree of the slave cylinder proportional servo valve includes: calculating the final opening degree of the slave cylinder proportional servo valve according to the following formula. in: —The final opening degree of the i-th slave cylinder proportional servo valve; —The correction opening of the i-th slave cylinder proportional servo valve. If no correction is needed, this item is... u i ''(t) ; —The reference opening of the main cylinder proportional servo valve is given by the upper-level controller according to the desired speed curve; —The compensated opening degree of the i-th slave cylinder proportional servo valve. If no compensation is required, this item is 0.

[0051] The above formula organically combines the reference command, displacement-based feedback correction, pressure-based safety correction, and load balancing-based feedforward compensation. It provides a unified motion benchmark; This ensures the safety of each individual slave cylinder; This coordinates the force interaction between the slave cylinder and the master cylinder.

[0052] In actual control, within a control cycle, when , , After all calculations are completed, the system performs this addition operation to generate the final command signal acting on the valve core: the final opening degree of the i-th slave cylinder proportional servo valve. u i (t) .

[0053] This embodiment employs a signal synthesis method that achieves multi-objective collaborative optimization control, ensuring both the synchronization of overall motion and the safety of individual cylinders while maintaining force balance among the cylinders. The final opening signal is the result of multiple optimizations, enabling the control system to perform excellently under various operating conditions and exhibiting extremely strong robustness.

[0054] In some embodiments of this application, certain safety control measures are also involved in the entire control process. One such measure involves setting a displacement upper limit. S max and one pressure limit P max During system operation, the displacement of all cylinder piston rods is continuously compared with the upper limit of displacement. S max Compare the pressures of all hydraulic cylinders with their upper pressure limits. P max Comparison. If the upper limit of displacement of any cylinder... S max or its pressure exceeds the pressure limit. P max If the abnormality is detected, the control system will immediately perform the following operations: cut off the control signal of the proportional servo valve of the cylinder; close the main shut-off valve at the pump station outlet to stop the oil supply of the entire system; trigger the audible and visual alarm to notify the operator; and record the abnormal event, while simultaneously sending the alarm information to the host computer via the wireless module.

[0055] Excessive displacement may indicate mechanical structural jamming or complete control failure; excessive pressure directly threatens the safety of pipelines and components. When either of these extreme conditions is detected, the system ceases its adjustment attempts and immediately interrupts energy supply to prevent the accident from escalating. This emergency stop protection strategy significantly improves construction safety, effectively preventing serious accidents such as hydraulic shocks, cylinder ejection, or damage to formwork structures caused by control failure. It protects expensive hydraulic equipment and bridge formwork, providing reliable safety assurance throughout the entire construction process.

[0056] Additionally, a pressure equalization-based safety monitoring strategy is provided. Specifically, in terms of cylinder layout, two sets of cylinders installed at adjacent locations are defined as monitoring pairs. The pressure difference between these cylinder pairs is calculated in real time and compared with a set tolerance. Δ p tol (This can be obtained through calibration) and compared. If the pressure difference between two adjacent sets of cylinders exceeds Δptol, the control system will: activate the audible and visual alarm to provide an early warning; output a command to reduce the opening of the proportional servo valves of these cylinders, thereby slowing down the overall movement speed of all cylinders and preventing uneven force distribution or collisions on the template by adjusting the opening of the proportional servo valves; and record all abnormal events and cylinder operation data in a historical database, providing a query interface for subsequent maintenance, statistical analysis, and optimization of control strategies.

[0057] Adjacent hydraulic cylinders, due to their close spatial position, should ideally have highly consistent loads and motion states. Significant pressure differences between them often directly indicate problems such as localized jamming or deformation of support points. Monitoring this pressure difference allows for the timely detection of potential mechanical issues. Reducing speed is intended to gently attempt to disengage from a jammed state or to prevent exacerbating the problem due to excessive speed.

[0058] This strategy extends safety from single-cylinder operation to system-wide coordinated safety, enabling timely detection of early signs of local mechanical failures and providing a window for manual intervention through a speed reduction alarm. This avoids potential equipment damage caused by forced high-speed operation under unknown conditions, demonstrating a high degree of intelligence.

[0059] Furthermore, another safety control strategy is provided: the system periodically calculates the pressure change ∆p / ∆t and piston rod displacement change ∆s / ∆t for each cylinder within a unit time (e.g., ∆t = 100 ms). A first change threshold is set. V p (Regarding pressure) and the second change threshold V s (Regarding displacement). If a certain hydraulic cylinder's... |∆p / ∆t|>V p Or |∆s / ∆t|> V s If the cylinder is deemed to pose a potential risk, an audible and visual alarm will be triggered immediately.

[0060] During normal operation of a hydraulic cylinder, pressure and displacement changes are relatively gradual. Dramatic pressure changes may indicate internal leakage or blockage; abnormal displacement changes (such as sudden speed changes) may indicate crawling, jamming, or external leakage. By monitoring these rates of change, early fault characteristics that are missed by traditional threshold monitoring can be detected.

[0061] This control method is a fault prediction method that can identify potential problems such as cylinder wear, seal leakage, or valve core jamming in advance, providing a basis for planned maintenance, significantly reducing unexpected downtime, extending equipment life, reducing overall maintenance costs, and improving project management.

[0062] In addition, this application also relates to a multi-cylinder synchronous control system for an internal mold hydraulic system used in bridge construction, including a master-slave definition module, a data acquisition module, an initial opening calculation module, a correction judgment module, a correction calculation module, a compensation judgment module, a compensation calculation module, a final opening calculation module, and an adjustment execution module. The master-slave definition module is used to select one cylinder from multiple cylinders as the master cylinder and the remaining cylinders as slave cylinders. The data acquisition module is used to acquire the piston rod displacement of the master cylinder, the piston rod displacement of the slave cylinders, and the pressure of the master cylinder and the slave cylinders. The initial opening calculation module calculates the initial opening of the slave cylinder proportional servo valve based on the displacement difference between each slave cylinder and the master cylinder. The correction judgment module determines whether the slave cylinder proportional servo valve needs adjustment based on the slave cylinder pressure. The initial opening of the slave cylinder proportional servo valve is corrected; when the correction calculation module determines that the initial opening of the slave cylinder proportional servo valve needs to be corrected, it calculates the corrected opening of the slave cylinder proportional servo valve; the compensation judgment module determines whether feedforward compensation of the opening of the slave cylinder proportional servo valve is needed based on the pressure difference between each slave cylinder and the master cylinder; when the compensation calculation module determines that feedforward compensation of the opening of the slave cylinder proportional servo valve is needed, it calculates the compensated opening of the slave cylinder proportional servo valve; the final opening calculation module calculates the final opening of the slave cylinder proportional servo valve based on the reference opening of the master cylinder proportional servo valve and the compensated and corrected openings of the slave cylinder proportional servo valve; the adjustment execution module adjusts the opening of the slave cylinder proportional servo valve based on the calculated final opening of the slave cylinder proportional servo valve.

[0063] The control system of this application embodies the aforementioned control method through modular design. Under the scheduling of the central processing unit, each module works collaboratively to complete a fully automated control closed loop from signal perception and intelligent decision-making to precise execution. This control system features clearly defined modules and functions, facilitating software programming, debugging, and maintenance. It transforms innovative control methods into a stable and reliable physical system, achieving automation, intelligence, and high safety in the synchronous control of the hydraulic system for the inner formwork of bridge construction, thus possessing extremely high engineering application value.

[0064] The control system of this application also includes a human-machine interaction module. Specifically, the human-machine interaction module is used to realize the visualization display and operation control of the entire process of internal mold operation, so that the operator can intuitively grasp the action status, synchronization accuracy and abnormal situation of the hydraulic cylinder, thereby improving construction safety and operation efficiency.

[0065] The main functions of the human-computer interaction module include: Real-time data display: The human-machine interface module displays the displacement and pressure signals of each hydraulic cylinder in real time, generating graphical representations of the curves, and simultaneously displays synchronization errors and alarm information. Operators can intuitively understand the cylinder's operating status, synchronization accuracy, and abnormal conditions, achieving visualized monitoring of the construction site.

[0066] Control Mode Switching: The system supports remote switching between automatic and manual modes via network. In automatic mode, the system operates according to closed-loop control logic, ensuring smooth and synchronized movement of the inner mold. In manual mode, the operator can make local adjustments or tests according to construction needs, improving construction flexibility.

[0067] Historical data recording and analysis: The system can record historical data of cylinder operation, including displacement, pressure, synchronization error, and abnormal events. This historical data can be used for construction quality assessment, equipment maintenance optimization, and anomaly diagnosis, providing a basis for subsequent construction and intelligent control strategy optimization.

[0068] The workflow of this module is as follows: First, user login Users access the system through a browser, and enter their username and password for verification before entering the main interface; Second, data loading After entering the system, it automatically connects to the server to obtain real-time monitoring data and 3D models; Third, interactive operation Users can switch views / query data through controls, or submit commands such as exception confirmation / alert settings, and all operations are fed back to the cloud database in real time.

[0069] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. A method for multi-cylinder synchronous control of an internal mold hydraulic system for bridge construction, characterized in that: include: Select one hydraulic cylinder from multiple hydraulic cylinders as the master cylinder, and the remaining hydraulic cylinders as slave cylinders; Collect the displacement of the master cylinder piston rod, the displacement of the slave cylinder piston rod, and the pressure of the master cylinder and the slave cylinder. The initial opening of the slave cylinder proportional servo valve is calculated based on the displacement difference between each slave cylinder and the master cylinder. The initial opening of the slave cylinder proportional servo valve needs to be corrected based on the slave cylinder pressure. If correction is needed, the corrected opening of the slave cylinder proportional servo valve is calculated. Based on the pressure difference between each slave cylinder and the master cylinder, determine whether feedforward compensation is needed for the opening of the slave cylinder proportional servo valve. If feedforward compensation is needed, calculate the compensation opening of the slave cylinder proportional servo valve. The final opening of the slave cylinder proportional servo valve is calculated based on the reference opening of the master cylinder proportional servo valve and the compensation and correction opening of the slave cylinder proportional servo valve. The opening degree of the slave cylinder proportional servo valve is adjusted based on the calculated final opening degree of the slave cylinder proportional servo valve. The method for determining whether the initial opening of the slave cylinder proportional servo valve needs to be corrected based on the slave cylinder pressure includes: if the ratio of the difference between the warning value and the slave cylinder pressure to the warning value is less than the set value, then it is determined that correction is needed; otherwise, no correction is needed. The warning value is less than the maximum permissible working pressure of the cylinder.

2. The method for multi-cylinder synchronous control of an internal mold hydraulic system for bridge construction according to claim 1, characterized in that: The method for calculating the initial opening of the slave cylinder proportional servo valve based on the displacement difference between each slave cylinder and the master cylinder includes: calculating the initial opening of the slave cylinder proportional servo valve according to the following formula. in: —The initial opening degree of the i-th slave cylinder proportional servo valve; —The displacement difference between the i-th slave cylinder and the master cylinder; K p —First displacement proportionality coefficient; K i —Second displacement proportionality coefficient; K d —Third displacement proportionality coefficient.

3. The multi-cylinder synchronous control method for an internal formwork hydraulic system used in bridge construction as described in claim 1, characterized in that: The method for calculating the corrected opening of the slave cylinder proportional servo valve includes: calculating the corrected opening of the slave cylinder proportional servo valve according to the following formula. in: —The corrected opening degree of the i-th slave cylinder proportional servo valve; —The initial opening degree of the i-th slave cylinder proportional servo valve; —The pressure scaling factor of the i-th cylinder; Calculate the pressure scaling factor using the following formula: in: —Lower limit of pressure scaling factor; —The pressure of the i-th cylinder; —Warning value; —From the cylinder's maximum permissible working pressure; — Pressure scaling sensitivity coefficient.

4. The multi-cylinder synchronous control method for an internal formwork hydraulic system used in bridge construction as described in claim 1, characterized in that: The method for determining whether feedforward compensation is needed for the opening of the proportional servo valve of the slave cylinder based on the pressure difference between each slave cylinder and the master cylinder includes: calculating the pressure difference between each slave cylinder and the master cylinder; if the pressure difference is greater than a set pressure difference threshold, it is determined that feedforward compensation is needed for the opening of the proportional servo valve of the slave cylinder; otherwise, feedforward compensation is not needed for the opening of the proportional servo valve of the slave cylinder.

5. The multi-cylinder synchronous control method for an internal formwork hydraulic system used in bridge construction as described in claim 4, characterized in that: The method for calculating the compensation opening of the slave cylinder proportional servo valve includes: calculating the compensation opening of the slave cylinder proportional servo valve according to the following formula. in: —The compensation opening degree of the i-th slave cylinder proportional servo valve; —The pressure difference between the i-th slave cylinder and the master cylinder; —Feedforward compensation ratio coefficient.

6. The multi-cylinder synchronous control method for an internal formwork hydraulic system used in bridge construction as described in claim 5, characterized in that: The method for calculating the final opening degree of the slave cylinder proportional servo valve includes: calculating the final opening degree of the slave cylinder proportional servo valve according to the following formula, in: —The final opening degree of the i-th slave cylinder proportional servo valve; —The corrected opening degree of the i-th slave cylinder proportional servo valve; —The reference opening degree of the main cylinder proportional servo valve; —The compensation opening degree of the i-th slave cylinder proportional servo valve.

7. The multi-cylinder synchronous control method for an internal formwork hydraulic system used in bridge construction as described in claim 1, characterized in that: The piston rod displacement of the slave cylinder is compared with the preset upper limit of displacement, and the slave cylinder pressure is compared with the preset upper limit of pressure. If the piston rod displacement of the slave cylinder exceeds the preset upper limit of displacement or the slave cylinder pressure exceeds the preset upper limit of pressure, the proportional servo valve signal of the slave cylinder is cut off, the pump station outlet valve is closed, and the emergency stop protection strategy is executed.

8. The multi-cylinder synchronous control method for an internal formwork hydraulic system used in bridge construction as described in claim 1, characterized in that: The pressure difference between two adjacent sets of hydraulic cylinders at the installation location is compared with the set tolerance. If the pressure difference between two adjacent sets of hydraulic cylinders exceeds the set tolerance, an audible and visual alarm is triggered, and the opening of the proportional servo valve of the hydraulic cylinder is controlled to reduce the hydraulic cylinder's operating speed.

9. A multi-cylinder synchronous control system for an internal formwork hydraulic system used in bridge construction, characterized in that: The control system operates according to a multi-cylinder synchronous control method for an internal formwork hydraulic system used in bridge construction as described in any one of claims 1 to 8. include, A master-slave definition module is used to select one cylinder from multiple cylinders as the master cylinder and the remaining cylinders as slave cylinders. The data acquisition module is used to acquire the displacement of the master cylinder piston rod, the displacement of the slave cylinder piston rod, and the pressure of the master cylinder and the pressure of the slave cylinder; An initial opening calculation module calculates the initial opening of the slave cylinder proportional servo valve based on the displacement difference between each slave cylinder and the master cylinder. The correction judgment module determines whether the initial opening of the slave cylinder proportional servo valve needs to be corrected based on the slave cylinder pressure. The correction calculation module calculates the corrected opening of the slave cylinder proportional servo valve when it determines that the initial opening of the slave cylinder proportional servo valve needs to be corrected. The compensation judgment module determines whether feedforward compensation is needed for the opening of the proportional servo valve of the slave cylinder based on the pressure difference between each slave cylinder and the master cylinder. The compensation calculation module calculates the compensation opening of the slave cylinder proportional servo valve when it determines that feedforward compensation is needed for the opening of the slave cylinder proportional servo valve. The final opening calculation module calculates the final opening of the slave cylinder proportional servo valve based on the reference opening of the master cylinder proportional servo valve and the compensated opening and corrected opening of the slave cylinder proportional servo valve. The adjustment execution module adjusts the opening of the slave cylinder proportional servo valve based on the calculated final opening of the slave cylinder proportional servo valve.

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