A method and system for multi-point synchronous lifting control of a suspension type bottom form of a lower beam of a tower

Abstract

The application discloses a kind of cable tower lower crossbeam suspension type bottom mould multi-point synchronous lifting control method and system, method includes: before lifting start, control system applies micro amplitude sine wave disturbance to each lifting point, gathers force and displacement response and calculates dynamic stiffness coefficient, constructs bottom mould stiffness matrix, inverse kinematics equation is solved to obtain initial pre-compensation displacement, after execution, bottom mould is lifted instantaneously without internal stress, and it is in geometric balance.Pose outer loop, load inner loop double closed loop model is built, outer loop is displaced trajectory with model predictive control planning, and dynamic weight factor is set in inner loop, and load deviation increases, and load safety is preferentially guaranteed.The objective function is constructed in each control cycle, and the optimal increment of valve control is obtained by rolling optimization, and abnormal lifting point is slightly delayed to release stress, and normal lifting point compensates stable posture.Command-driven hoist cooperates, and after reaching the standard, hydraulic is locked, anchoring is completed, and system conversion is realized.Provide reliable technical support for bridge construction technology upgrading.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering construction technology, and more specifically, relates to a method and system for controlling the multi-point synchronous lifting of the bottom formwork of the suspended crossbeam under the cable tower. Background Technology

[0002] The crossbeams under the pylons of long-span cable-stayed and suspension bridges are key load-bearing components of the bridge superstructure. Their construction precision and structural safety directly affect the overall load-bearing capacity and service life of the bridge. Multi-point hydraulic synchronous lifting of the suspended bottom formwork is the core technology for high-altitude construction of the crossbeams under the pylons. This technology relies on the coordinated operation of multiple hydraulic lifters to achieve stable hoisting and accurate positioning of large-tonnage bottom formwork systems, and is widely used in modern bridge engineering.

[0003] Current traditional lifting control technologies have many limitations and are difficult to adapt to the high-standard construction requirements of modern bridge engineering. Traditional control schemes mostly focus on displacement synchronization as the core objective, failing to fully consider the nonlinear sag effect of the lifting steel strands, and also failing to construct a system mechanical model that incorporates changes in lifting height and the influence of wind loads in the on-site environment. This results in significant deviations between the control basis and the actual working conditions. Before the lifting operation begins, there is a lack of system stiffness identification and initial pre-compensation, making it impossible to eliminate structural gaps and rigging slack in advance. This can easily lead to problems such as uneven stress, localized internal stress concentration, and attitude deviation during the lifting of the bottom formwork.

[0004] During multi-point coordinated lifting, the control strategy cannot achieve dynamic coordination between attitude control and load control. Simply pursuing displacement synchronization easily leads to load imbalance at the lifting points. When some lifting points experience overload or underload, the control system cannot adjust control priorities in time, potentially causing the bottom formwork to tilt, the steel strands to exceed stress limits, and posing structural safety risks. Furthermore, the flow saturation and pressure safety boundaries of the hydraulic system are not incorporated into the control constraints, easily leading to frequent hydraulic valve actuations and severe system pressure fluctuations, reducing the stability of the lifting process.

[0005] Under abnormal stress conditions, traditional control systems lack stress release and multi-point coordinated compensation capabilities, easily causing damage to the bottom formwork structure and lifting equipment. The system transition process after lifting into position relies on manual judgment and operation, resulting in low automation levels, difficulty in accurately controlling load deviations and attitude errors, low anchoring efficiency, and significant construction safety hazards.

[0006] As bridge engineering rapidly develops towards large-span, high-pier, and intelligent construction, existing control technologies can no longer meet the requirements of high precision, high safety, and high automation. Developing new lifting control technologies to address issues such as stress imbalance, inaccurate posture, high safety risks, and insufficient intelligence in traditional processes is of great significance for ensuring the construction quality of the crossbeams under the pylons, improving project efficiency, and promoting the upgrading of bridge construction technology. Summary of the Invention

[0007] This invention aims to solve problems such as stress imbalance, posture deviation, initial internal stress concentration and insufficient intelligent control in the multi-point synchronous lifting of the bottom formwork of the suspended beam under the cable tower. Through stiffness identification, dual closed-loop dynamic control and collaborative compensation strategy, it realizes the coordinated control of posture and load throughout the lifting process, ensures construction safety and accuracy, and completes the transformation to an efficient and automated system.

[0008] To address the aforementioned deficiencies or improvement needs of existing technologies, as a first aspect of this invention, the present invention provides a multi-point synchronous lifting control method for a suspended bottom formwork of a cable tower, comprising: S1. Before the lifting starts, the control system controls each hydraulic lifting device to apply a small-amplitude sinusoidal wave disturbance signal to each lifting point, collects the force response and displacement response of each lifting point, calculates the actual dynamic stiffness coefficient of each lifting point under the current cable length, and constructs the stiffness matrix of the bottom formwork system; based on the stiffness matrix and the preset horizontal attitude target of the bottom formwork, the initial pre-compensation displacement required for each lifting point to eliminate structural gaps and cable slack is calculated by solving the inverse kinematic equation, and each lifting point is controlled to execute the pre-compensation displacement so that the bottom formwork system is in a geometric equilibrium state without internal stress at the moment of lifting; S2. Establish a dual closed-loop control model with the overall attitude error of the bottom mold as the outer loop and the load deviation of each lifting point as the inner loop; in the outer loop, the model predictive control algorithm is used to predict the displacement trajectory in the future time domain based on the current attitude; in the inner loop, a dynamic weighting factor is introduced, which has a positive correlation function with the real-time load deviation rate of each lifting point; when the load deviation rate of a certain lifting point increases, the weighting factor corresponding to that point is automatically increased, thereby increasing the priority of load following at that point and decreasing the priority of displacement synchronization in the control law; S3. Construct an objective function within each control cycle, the objective function aiming to minimize the weighted attitude error and load imbalance; solve the optimal control increment sequence for each hydraulic lifter using a rolling optimization algorithm; use the first control increment in the sequence to correct the opening of the hydraulic proportional valve, so that when a certain lifting point experiences abnormal stress, that lifting point is allowed to generate a small displacement hysteresis to release internal stress, while other normal lifting points maintain the stability of the overall attitude of the bottom mold through a compensation algorithm; S4. Convert the corrected control commands into electrical signals to drive each hydraulic lifter to move in coordination. During the lifting process, when the bottom formwork is lifted to the design elevation and the load deviation and attitude error of all lifting points converge to the threshold range allowed by the system conversion, the hydraulic lifters are automatically locked and the anchoring command of the bottom formwork and the cable tower embedded parts is triggered to complete the system conversion from the suspended lifting state to the supported force state.

[0009] Furthermore, in S1, when constructing the stiffness matrix of the bottom mold system, a nonlinear sag effect correction term for the lifting steel strand is introduced. The specific implementation steps include: A catenary mechanical model of steel strand is established, and the local tangential stiffness matrix of steel strand under the current tension state is derived based on the catenary equation. The tangential stiffness matrix includes material elastic stiffness terms and geometric nonlinear stiffness terms caused by self-weight sag. The local tangent stiffness matrix is ​​mapped to the global coordinate system by coordinate transformation to obtain the global stiffness matrix of the steel strand at each suspension point; Constructing nonlinear correction coefficients for height-wind speed coupling The coefficient is used to perform a weighted correction on the global stiffness matrix of the steel strand to characterize the lifting height. The sag effect caused by the change and the ambient wind speed The resulting change in aerodynamic stiffness; The corrected stiffness matrix of the steel strands at each suspension point is compared with the finite element structural stiffness matrix of the bottom formwork truss. Finite element analysis was performed to generate the overall stiffness matrix of the bottom formwork system. .

[0010] Furthermore, in S1, when calculating the initial pre-compensation displacement required to eliminate structural gaps and rigging slack at each suspension point by solving the inverse kinematic equations, the damped least squares (DLS) method is used to solve the generalized inverse of the Jacobian matrix to ensure the robustness and convergence of the calculation process. The specific calculation process is as follows: in, This represents the calculated initial pre-compensation displacement vector required for each lifting point. The Jacobian matrix of the system establishes the mapping relationship between the operating space and joint space of the bottom mold system, reflecting the current kinematic geometry of the system; The matrix representing the transpose of the Jacobian matrix; Let be the damping factor, a non-negative scalar parameter. The main purpose of introducing the damping factor is to improve the matrix. The condition number is used to prevent the calculation results from diverging when the system approaches a singular configuration; It is an identity matrix, and its dimensions are... The same, used to construct regularization terms; The preset attitude error target vector represents the deviation between the actual attitude of the current bottom mold system and the desired target attitude.

[0011] Furthermore, the dual closed-loop control model in S2 is constructed as a cascaded control structure that combines outer loop attitude control and inner loop load control. Among them, the outer ring serves as the position control ring, and its control objective is to eliminate the attitude error of the bottom mold system. This attitude error is obtained through a machine vision-based three-dimensional coordinate feedback mechanism. Specifically, high-precision visual targets are deployed at key monitoring points of the tower and the bottom mold. The spatial coordinate information of the targets is collected in real time through an industrial camera array. The current six-degree-of-freedom pose of the bottom mold is obtained through the attitude calculation method and compared with the preset target pose to generate an attitude deviation signal. The inner ring serves as a force control ring, with the control objective of eliminating load deviations between various lifting points to prevent structural tilting or instability caused by eccentric loading. The feedback signal for this load deviation originates from the data fusion of a pressure sensor and a hollow force sensor. Specifically, the pressure sensor is installed at the inlet of the hydraulic lifting cylinder to monitor the hydraulic thrust, while the hollow force sensor is connected in series at the anchoring end of the steel strand to directly measure the cable force. The data from the two sensors are redundant and mutually verified, together forming a highly reliable load feedback loop.

[0012] Furthermore, the objective function of the model predictive control algorithm in S2 not only includes minimizing the bottom mold attitude tracking error, but also explicitly introduces the flow saturation constraint and pressure safety boundary constraint of the hydraulic system, specifically as follows: At each time step of the rolling optimization The controller predicts the flow demand of each hydraulic lifting cylinder in the future time domain based on the discrete state-space model of the system. ; During the rolling optimization process, the predicted traffic demand is monitored in real time. The maximum flow rate of the proportional valve is related to its physical limit parameter. The relationship between them; if the flow demand of one or more hanging points is predicted. The maximum flow rate limit of the proportional valve is about to be exceeded. This triggers the flow saturation constraint mechanism; at this point, the optimization solver will automatically adjust the control increment. The output of the flow is limited by adjusting the decision variables; To prevent system instability caused by flow rate limitations, a dynamic weighting strategy based on load priority is adopted: in the weighting matrix of the objective function, the flow rate supply weight for lifting points with larger loads is automatically increased to prioritize the stability of their operation and prevent the load from falling or tilting; at the same time, the weight coefficient of the displacement synchronization error term is dynamically reduced, allowing the system to experience slight displacement asynchrony for a short period of time in exchange for meeting the physical constraints. ; Furthermore, the pressure safety boundary constraint is used to prevent the hydraulic system from generating excessively high peak pressures during acceleration or braking; in the optimization calculation, the real-time pressure of the hydraulic circuit is considered. As a constraint condition, it is added to the set of inequality constraints, that is, it requires When the predicted pressure approaches the safety boundary, the control increment is also adjusted. This slows down the movement of the hydraulic cylinder, thereby smoothing out pressure fluctuations.

[0013] Furthermore, the calculation formula for the dynamic weighting factor in S2 is set to an exponential decay function form, specifically expressed as: in, Representing the The first hanging point The real-time load deviation within each control cycle is the absolute value of the difference between the current actual measured load and the ideal equilibrium load. A preset load imbalance threshold is set, which defines the safe range of load deviation allowed by the system. This is the gain coefficient, used to adjust the sensitivity of the weighting factor to changes in load deviation. The larger the value, the faster the weight increases with the deviation.

[0014] Furthermore, in step S3, the optimal control increment sequence for each hydraulic lifter is solved using a rolling optimization algorithm, specifically including: First, a quadratic objective function is constructed, which includes attitude tracking terms, load balancing terms, and control quantity suppression terms. ;in, The current sampling time is indicated; the attitude tracking term is used to measure the deviation between the bottom mold attitude and the set trajectory, and is defined as the norm of the product of the bottom mold attitude error vector and the dynamic weight matrix in the prediction time domain; the load balancing term is used to balance the force on each lifting point, and is defined as the weighted sum of squares of the load deviation rates of each lifting point; the control quantity suppression term is used to prevent the hydraulic proportional valve from operating too frequently, and is defined as a penalty function for the rate of change of the hydraulic proportional valve opening; when solving this objective function, physical constraints of the hydraulic lifter are introduced as inequality constraints, including the maximum lifting speed, the maximum acceleration, and the pressure saturation threshold of the hydraulic system, to ensure that the calculated control commands meet the physical execution limits of the equipment; Subsequently, the Sequential Quadratic Programming (SQP) algorithm is used to iteratively solve the constrained quadratic objective function to calculate the optimal control increment sequence in the future prediction time domain. ;in, This represents the length of the prediction time domain, i.e., the number of steps the optimization algorithm takes to predict forward; to They represent from the current moment respectively From the beginning to the future The control increment sequence at each time step. This indicates the adjustment amount of the hydraulic proportional valve opening.

[0015] Furthermore, in S3, the opening degree of the hydraulic proportional valve is corrected using the first control increment in the sequence, specifically by implementing the following collaborative compensation strategy: When the first When an abnormal stress occurs at a single lifting point and its load deviation rate exceeds the preset stress relief threshold, The lifting point is numbered, and a compliant control factor is introduced into the control loop of that lifting point in the control system. The first control increment was revised to This correction reduces the response speed of the suspension point, allowing it to produce a small displacement hysteresis to release internal stress. Meanwhile, in order to offset the impact of the aforementioned lag on the overall attitude, the first... The attitude deviation vector caused by deceleration at each suspension point and the deviation vector The compensation increment is generated by allocating the compensation based on the dynamic weight factor ratio of the remaining normal lifting points. ; the compensation increment This is superimposed on the first control increment of the remaining normal lifting points, so that the remaining normal lifting points, while maintaining the overall posture of the bottom formwork, share the burden of the first control increment. The load was unloaded from each lifting point.

[0016] As a second aspect of the present invention, a multi-point synchronous lifting control system for a bottom formwork suspended from a pylon lower beam is also provided, comprising: The stiffness identification and pre-compensation unit is used to control each hydraulic lifting device to apply a small-amplitude sinusoidal disturbance signal to each lifting point before the lifting starts. It collects the force response and displacement response of each lifting point, calculates the actual dynamic stiffness coefficient of each lifting point under the current cable length, and constructs the stiffness matrix of the bottom formwork system. Based on the stiffness matrix and the preset horizontal attitude target of the bottom formwork, it calculates the initial pre-compensation displacement required for each lifting point to eliminate structural gaps and cable slack by solving the inverse kinematic equations, and controls each lifting point to execute the pre-compensation displacement so that the bottom formwork system is in a geometric equilibrium state without internal stress at the moment of lifting. A dual-loop and dynamic weighting unit is used to establish a dual-loop control model with the overall attitude error of the bottom mold as the outer loop and the load deviation of each lifting point as the inner loop. In the outer loop, the model predictive control algorithm is used to predict the displacement trajectory in the future time domain based on the current attitude. In the inner loop, a dynamic weighting factor is introduced, which has a positive correlation function with the real-time load deviation rate of each lifting point. When the load deviation rate of a certain lifting point increases, the weighting factor corresponding to that point is automatically increased, thereby increasing the priority of load following at that point and decreasing the priority of displacement synchronization in the control law. The rolling optimization and valve control correction unit is used to construct an objective function in each control cycle. The objective function aims to minimize the weighted attitude error and load imbalance. The optimal control increment sequence for each hydraulic lifter is solved by the rolling optimization algorithm. The opening of the hydraulic proportional valve is corrected by the first control increment in the sequence, so that when a lifting point is subjected to abnormal force, the lifting point is allowed to produce a small displacement hysteresis to release internal stress, while other normal lifting points maintain the stability of the overall attitude of the bottom mold through the compensation algorithm. The coordinated action and system conversion unit is used to convert the modified control commands into electrical signals to drive the coordinated action of each hydraulic lifter. During the lifting process, when the bottom formwork is lifted to the design elevation and the load deviation and attitude error of all lifting points converge to the threshold range allowed by the system conversion, the hydraulic lifters are automatically locked and the anchoring command of the bottom formwork and the cable tower embedded parts is triggered, thus completing the system conversion from the suspended lifting state to the supported stress state.

[0017] As a third aspect of the invention, a computer-readable storage medium is also provided, on which a computer program is stored, which is executed by a processor as described in any one of the claims, a method for multi-point synchronous lifting control of a bottom formwork suspended from a pylon lower beam.

[0018] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The present invention provides a multi-point synchronous lifting control method for a suspended bottom formwork of a cable tower. Before lifting begins, each hydraulic lifting device applies a small-amplitude sinusoidal disturbance signal to each lifting point, collects the force and displacement responses of each lifting point, calculates the actual dynamic stiffness coefficient of each lifting point under the current cable length, and constructs the stiffness matrix of the bottom formwork system. Based on the stiffness matrix and a preset horizontal attitude target, the inverse kinematic equation is solved, and the initial pre-compensation displacement of each lifting point is calculated and controlled to eliminate structural gaps and cable slack. This operation can identify the true mechanical characteristics of the system, effectively eliminate the initial deviations caused by structural gaps and cable slack, and ensure that the bottom formwork system is in a geometrically balanced state without internal stress at the moment of lifting. This avoids problems such as uneven force, attitude deviation, and stress concentration during the lifting stage. The damped least squares method ensures the robustness of the calculation process, avoids calculation anomalies caused by singular configurations, provides a stable initial mechanical state for subsequent lifting operations, and improves the safety and controllability of the system during the start-up phase.

[0019] 2. The multi-point synchronous lifting control method for the suspended bottom formwork of the cable tower's lower beam of the present invention establishes a dual closed-loop control model with the overall attitude error of the bottom formwork as the outer loop and the load deviation of each lifting point as the inner loop. The outer loop uses a model predictive control algorithm to predict the displacement trajectory in the future time domain based on the current attitude, while the inner loop introduces a dynamic weighting factor that is positively correlated with the real-time load deviation rate of each lifting point. The outer loop obtains the bottom formwork's posture information through machine vision to ensure attitude control accuracy, while the inner loop obtains load feedback through multi-sensor data fusion to ensure load monitoring reliability. The dynamic weighting factor can increase the load following priority of a lifting point and decrease the displacement synchronization priority when the load deviation rate of the lifting point increases, balancing the control requirements of attitude synchronization and load safety. Combined with an extended Kalman filter to filter out measurement noise, it reduces the frequent operation of hydraulic proportional valves, improves the stability and accuracy of control during the lifting process, and effectively prevents structural instability caused by off-center loading and overload.

[0020] 3. The multi-point synchronous lifting control method for the suspended bottom formwork of the cable tower's lower beam of the present invention constructs an objective function that minimizes the weighted attitude error and load imbalance in each control cycle. The optimal control increment sequence for each hydraulic lifter is solved using a rolling optimization algorithm. The opening of the hydraulic proportional valve is corrected using the first control increment of the sequence. Suspension points under abnormal stress experience slight displacement, releasing internal stress with lag. Normal suspension points maintain overall formwork stability through a compensation algorithm. Finally, the correction command is converted into an electrical signal to drive the lifters to coordinate their actions. Upon reaching the target, the hydraulic system is automatically locked, and the anchoring system conversion is completed. This method can generate control commands that conform to the physical constraints of the equipment, achieving stress release and overall attitude stability under abnormal working conditions. During the lifting process, the elevation, load, and attitude errors are verified in real time. The system automatically completes the conversion from suspended lifting to supported stress, improving the degree of construction automation, accurately controlling system conversion parameters, reducing safety hazards caused by manual operation, and ensuring stability and safety throughout the lifting process. Attached Figure Description

[0021] Figure 1 This is a flowchart of a multi-point synchronous lifting control method for a suspended bottom formwork of a cable tower beam according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall lifting of the crossbeam according to an embodiment of the present invention; Figure 3 Stress cloud diagram of the suspension system and bottom formwork truss according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the system units in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Example 1 Please refer to Figure 1 This embodiment 1 provides a multi-point synchronous lifting control method for the bottom formwork of a cable tower with a suspended crossbeam, including: S1. Before the lifting starts, the control system controls each hydraulic lifting device to apply a small-amplitude sinusoidal wave disturbance signal to each lifting point, collects the force response and displacement response of each lifting point, calculates the actual dynamic stiffness coefficient of each lifting point under the current cable length, and constructs the stiffness matrix of the bottom formwork system; based on the stiffness matrix and the preset horizontal attitude target of the bottom formwork, the initial pre-compensation displacement required for each lifting point to eliminate structural gaps and cable slack is calculated by solving the inverse kinematic equation, and each lifting point is controlled to execute the pre-compensation displacement so that the bottom formwork system is in a geometric equilibrium state without internal stress at the moment of lifting; S2. Establish a dual closed-loop control model with the overall attitude error of the bottom mold as the outer loop and the load deviation of each lifting point as the inner loop; in the outer loop, the model predictive control algorithm is used to predict the displacement trajectory in the future time domain based on the current attitude; in the inner loop, a dynamic weighting factor is introduced, which has a positive correlation function with the real-time load deviation rate of each lifting point; when the load deviation rate of a certain lifting point increases, the weighting factor corresponding to that point is automatically increased, thereby increasing the priority of load following at that point and decreasing the priority of displacement synchronization in the control law; S3. Construct an objective function within each control cycle, the objective function aiming to minimize the weighted attitude error and load imbalance; solve the optimal control increment sequence for each hydraulic lifter using a rolling optimization algorithm; use the first control increment in the sequence to correct the opening of the hydraulic proportional valve, so that when a certain lifting point experiences abnormal stress, that lifting point is allowed to generate a small displacement hysteresis to release internal stress, while other normal lifting points maintain the stability of the overall attitude of the bottom mold through a compensation algorithm; S4. Convert the corrected control commands into electrical signals to drive each hydraulic lifter to move in coordination. During the lifting process, when the bottom formwork is lifted to the design elevation and the load deviation and attitude error of all lifting points converge to the threshold range allowed by the system conversion, the hydraulic lifters are automatically locked and the anchoring command of the bottom formwork and the cable tower embedded parts is triggered to complete the system conversion from the suspended lifting state to the supported force state.

[0024] Please refer to Figure 2 as well as Figure 3 This embodiment 1 further elaborates on the above steps.

[0025] (1) Stiffness identification and pre-compensation Before the formal lifting operation of the suspended bottom formwork under the pylon begins, the on-site construction environment and the characteristics of the structure itself will bring many adverse effects to the lifting control. Issues such as the sag of the steel strands with length, aerodynamic interference caused by on-site wind speed, structural gaps and slack in the rigging can all lead to uneven stress and posture deviation during the lifting of the bottom formwork. To eliminate these initial hidden dangers, it is necessary to conduct stiffness identification first.

[0026] In other preferred embodiments, the control system sends commands via a communication network to the hydraulic lifters distributed at each lifting point, requiring all lifters to synchronously output a small-amplitude sinusoidal disturbance signal. The amplitude of this disturbance signal is strictly limited to 1%-3% of the rated thrust of the hydraulic system, and the frequency is set to a low-frequency band of 0.5Hz-2Hz to ensure that the applied energy is only sufficient to excite micro-elastic deformation between the steel strands and the bottom formwork structure, without causing the bottom formwork to detach from the support surface or produce significant macro-displacement. This "small-amplitude" disturbance is the best means of detecting the internal stiffness distribution without changing the original static equilibrium state of the structure. Simultaneously with the application of the disturbance, high-precision force sensors and displacement sensors deployed at each lifting point begin to synchronously collect data. The force sensors record the pressure changes in the hydraulic cylinders and the cable force fluctuations of the series steel strands, while the displacement sensors capture the actual stroke changes of the lifting head under small excitations. The control system receives and processes this timing data, and by calculating the ratio of the force response amplitude to the displacement response amplitude multiple, it calculates the actual dynamic stiffness coefficient of each lifting point under the current specific cable length and initial tension state. ,in This is the actual dynamic stiffness coefficient, representing the structure's ability to resist deformation under the current cable length and load conditions at the suspension point; Force response amplitude refers to the peak value of the fluctuation of cylinder tension (or cable force) collected by the hydraulic system sensor after a sinusoidal perturbation is applied; The displacement response amplitude refers to the peak value of the actual displacement fluctuation generated at the corresponding lifting point of the bottom formwork under the same disturbance.

[0027] After calculating the dynamic stiffness coefficients of the lifting points, it is necessary to construct a stiffness matrix for the bottom formwork system that can comprehensively reflect the actual working conditions. The specific process is as follows: First, a catenary geometric model of the steel strand is established. A single lifting steel strand is considered a flexible cable, and its curve equation follows the catenary theory: ;in, The horizontal coordinates are along the span of the steel strand. The verticality at that coordinate; This represents the horizontal tension component of the steel strand. The weight per unit length is used. This equation is used to calculate the stress-free length of the steel strand under the current tension. and the current length after elastic elongation This provides a geometric basis for subsequent stiffness calculations.

[0028] Secondly, the equivalent tangential stiffness matrix of the steel strand is derived. In the local coordinate system, this matrix consists of two parts: the elastic stiffness of the material and its geometric stiffness. ;in, For the tensile stiffness of the steel strand, This is the geometric stiffness matrix, used to correct for sag effects. The geometric stiffness term can be simplified to... This formula reflects the tension Steel strand length The impact on stiffness.

[0029] Next, an environmental correction factor is introduced. And it is applied to the stiffness matrix of steel strands. Taking into account the lifting height... Changes in the length of the steel strand will lead to changes in the sag effect, which in turn will significantly alter the sag effect; at the same time, the ambient wind speed... This generates lateral aerodynamic forces, altering the equivalent tension distribution of the cable. A nonlinear correction coefficient is defined. ,in These are Irwin parameters, reflecting the effect of sag, and are related to cable length (i.e., lift height). Proportional to; The wind-induced stiffness reduction factor was obtained by fitting wind tunnel test data. The calculated tangential stiffness matrix of a single steel strand was then used. Multiplying by this correction factor yields the corrected stiffness matrix considering environmental factors. This step ensures that the stiffness matrix of the steel strand reflects the mechanical properties under actual conditions.

[0030] Then, coordinate transformation and stiffness matrix assembly are performed. The corrected steel strand stiffness matrix is ​​then... Through coordinate transformation matrix Transform to global coordinate system: This step ensures that the stiffness matrices of each steel strand are superimposed in a unified coordinate system.

[0031] Finally, the overall stiffness matrix of the assembled bottom formwork system. The global stiffness matrix of the steel strands at all lifting points is compared with the finite element stiffness matrix of the bottom formwork truss. Finite element analysis was performed to obtain the overall stiffness matrix of the bottom formwork system. ,in To increase the number of lifting points, this matrix comprehensively considers the structural stiffness, the sag effect of the steel strands, and the influence of environmental factors (height, wind speed), providing an accurate model for subsequent construction deformation prediction and stress analysis.

[0032] After obtaining the overall stiffness matrix of the bottom formwork system, and combining this stiffness matrix with the preset horizontal attitude target of the bottom formwork, the initial pre-compensation displacement required to eliminate structural gaps and rigging slack at each suspension point is calculated by solving the inverse kinematic equations. Since the bottom formwork system suspended by the lower beam of the tower may have redundant degrees of freedom or near-singular configurations during the lifting process, directly solving the inverse Jacobian matrix would lead to numerical instability or no solution. Therefore, the damped least squares (DLS) method is used to solve the generalized inverse of the Jacobian matrix to ensure the robustness and convergence of the calculation process. The specific calculation process is as follows: in, This represents the calculated initial pre-compensation displacement vector required for each lifting point. The Jacobian matrix of the bottom mold system establishes the mapping relationship between the operating space and joint space of the bottom mold system, reflecting the current kinematic geometry of the bottom mold system; The matrix representing the transpose of the Jacobian matrix; Let be the damping factor, a non-negative scalar parameter. The main purpose of introducing the damping factor is to improve the matrix. The condition number is used to prevent the calculation results from diverging when approaching singular configurations; It is an identity matrix, and its dimensions are... The same, used to construct regularization terms; The preset attitude error target vector represents the deviation between the actual attitude of the current bottom mold system and the desired target attitude.

[0033] To further improve the stability of the bottom mold system, the damping factor The system dynamically adjusts based on the singular values ​​of the torque at each lifting point. Specifically, the bottom mold system monitors the distribution of singular values ​​in the Jacobian matrix in real time. When the minimum singular value approaches zero, indicating that the bottom mold system is approaching a singular configuration, the damping factor is automatically increased. The value of the regularization term. This dynamic adjustment mechanism can effectively increase the weight of the regularization term, thereby preventing the system from going out of control under singular configurations and ensuring the stability and safety of the initial pre-compensation process.

[0034] After calculating the pre-compensation displacement required to eliminate structural gaps and slack in the rigging at each lifting point, the control system drives each lifting point to complete the displacement, so that the bottom formwork system is in a geometrically balanced state without internal stress at the moment of lifting, laying the foundation for subsequent smooth lifting.

[0035] (2) Double closed loop and dynamic weight During the bottom formwork lifting process, accurate attitude control and load balancing at the lifting points need to be achieved simultaneously. A single control mode is difficult to cope with structural disturbances and environmental interference. Therefore, this embodiment adopts a dual closed-loop cascaded control architecture that combines outer-loop attitude control and inner-loop load control.

[0036] The outer loop serves as the position control loop, and its control objective is to eliminate the attitude error of the bottom mold system. This attitude error is obtained through a machine vision-based 3D coordinate feedback mechanism. In other preferred implementations, the specific process for obtaining the attitude error is as follows: First, establish the hardware topology for visual measurement. On the stable structure of the crossbeam construction area under the pylon, a fixed array of at least two high-resolution, high-frame-rate industrial cameras is installed. The camera lenses are equipped with narrow-band filters to suppress interference from welding arc light and sunlight reflection. High-precision spherical visual targets are rigidly connected to key control points of the bottom formwork truss (typically directly below the lifting points and at the geometric center of the bottom formwork). These targets are coated with high-contrast fluorescent material and incorporate built-in infrared LEDs as active light sources, ensuring clear identification even at night or in low-light conditions.

[0037] Secondly, camera calibration and spatial reconstruction are performed. The Zhang Zhengyou calibration method is used for offline calibration of the industrial camera array, obtaining the camera's intrinsic parameter matrix (including focal length, principal point coordinates, and distortion coefficients) and extrinsic parameter matrix (the camera's rotation and translation matrix in the world coordinate system). A control network is deployed on-site, and several reference target points with known absolute coordinates are selected. The camera's extrinsic parameters are optimized using the least squares method to establish a unified world coordinate system. After the camera array captures the target image, grayscale, binarization, and centroid extraction algorithms are used to accurately locate the target's two-dimensional pixel coordinates in the image. Using a calibrated projection matrix, the two-dimensional coordinates of the same target captured by the left and right cameras (or multi-view cameras) are triangulated to calculate the three-dimensional spatial coordinates of the target in the world coordinate system. .

[0038] Next, rigid body pose calculation is performed. The bottom mold system is considered as a rigid body, and the pose of the components distributed on it is calculated. Non-collinear target points (usually taken) The real-time 3D coordinates are used to construct the spatial geometric model of the rigid body. Let the coordinates of the target point of the bottom mold in its initial equilibrium state be the reference point set. The set of points measured at the current time is Using quaternion-based absolute orientation algorithms (such as the Wahba problem), a rotation matrix is ​​calculated. and a translation vector , making the error function To reach the minimum. Among them, Weighting coefficients are set based on the importance of target location or measurement confidence.

[0039] Through the above optimized calculations, the rotation matrix... The translation vector directly represents the current pitch, roll, and yaw angles of the bottom formwork. This indicates that the centroid of the bottom mold is in , , Linear displacement on the axis. The calculated current six-DOF pose. With the preset target pose By comparing and subtracting, we obtain the real-time attitude error vector. The attitude error vector serves as the feedback input to the outer loop controller, driving the model predictive control algorithm to plan the correction trajectory, thereby achieving high-precision attitude closed-loop control during the bottom mold lifting process.

[0040] The outer loop control employs a model predictive control algorithm for displacement trajectory planning. The algorithm minimizes attitude tracking error while incorporating hydraulic system flow saturation and pressure safety boundary constraints. This is achieved at each time step of the rolling optimization process. The controller is based on a discrete state model of the hydraulic system and predicts the flow demand of each hydraulic cylinder in future periods during each control cycle. During the rolling optimization process, the predicted traffic demand is monitored in real time. The maximum flow rate of the proportional valve is related to its physical limit parameter. The relationship between them; if the flow demand of one or more hanging points is predicted. The maximum flow rate limit of the proportional valve is about to be exceeded. This triggers the flow saturation constraint mechanism; at this point, the optimization solver will automatically adjust the control increment. The output of the flow is limited by adjusting the decision variables; To prevent hydraulic system instability caused by flow restriction, a dynamic weight adjustment strategy based on load priority is adopted: in the weighting matrix of the objective function, the flow supply weight for lifting points with larger loads is automatically increased to prioritize the stability of their operation and prevent the load from falling or tilting; at the same time, the weight coefficient of the displacement synchronization error term is dynamically reduced, allowing the hydraulic system to experience slight displacement asynchrony for a short period of time in exchange for meeting physical constraints. ; Furthermore, the pressure safety boundary constraint is used to prevent the hydraulic system from generating excessively high peak pressures during acceleration or braking; in the optimization calculation, the real-time pressure of the hydraulic circuit is considered. As a constraint condition, it is added to the set of inequality constraints, that is, it requires When the predicted pressure approaches the safety boundary, the control increment is also adjusted. This slows down the movement speed of the hydraulic cylinder, thereby smoothing pressure fluctuations and protecting the stable operation of the hydraulic system.

[0041] Meanwhile, in the inner loop load control, the inner loop acts as a force control loop, and its control objective is to eliminate load deviations between various lifting points to prevent structural tilting or instability caused by eccentric loading. The feedback signal of this load deviation comes from the data fusion of pressure sensors and hollow force sensors. Specifically, the pressure sensor is installed at the oil inlet of the hydraulic lifting cylinder to monitor the hydraulic thrust, while the hollow force sensor is connected in series at the anchoring end of the steel strand to directly measure the cable force. The data from the two sensors are redundant and mutually verified, together forming a highly reliable load feedback loop.

[0042] The inner-loop control introduces a dynamic weighting factor that is positively correlated with the real-time load deviation rate of the lifting point, enabling adaptive adjustment of the control priority. The calculation formula for the dynamic weighting factor is set to an exponential decay function, specifically expressed as: in, Representing the The first hanging point The real-time load deviation within each control cycle is the absolute value of the difference between the current actual measured load and the ideal equilibrium load. A preset load imbalance threshold is set, which defines the safe range of allowable load deviation. This is the gain coefficient, used to adjust the sensitivity of the weighting factor to changes in load deviation. The larger the value, the faster the weight increases with the deviation.

[0043] The design logic of this exponential decay function lies in utilizing the nonlinear amplification characteristic of the exponential function to "penalize" load deviations exceeding the safety threshold. When the real-time load deviation... Less than or equal to the threshold At that time, weighting factor When maintained at a low level (less than or equal to 1), the controller will consider other indicators such as displacement synchronization during the optimization process; however, when When a serious risk of overloading or uneven loading is detected at a certain lifting point, the exponential term increases rapidly, causing the weighting factor to... The weight increases exponentially, thus increasing the load following priority at this lifting point in the control law and decreasing the displacement synchronization priority. This rapidly increasing weight forces the objective function to assign the highest priority to eliminating the load deviation at this excessive point during the rolling optimization process. This compels the optimizer to output control commands that can quickly reduce the deviation, thereby ensuring that the lifting system can prioritize the structural safety when facing sudden load disturbances and avoid structural damage or lifting instability caused by local overload.

[0044] To further improve control accuracy and eliminate interference from environmental noise and high-frequency vibrations in attitude calculation, this embodiment introduces an Extended Kalman Filter (EKF) algorithm during the fusion of visual measurement system and sensor data. Visual measurements are susceptible to abrupt changes due to illumination variations, while force sensors are prone to high-frequency noise from mechanical vibrations. Directly using this data would lead to frequent actuation of the hydraulic proportional valve. The EKF establishes a nonlinear state-space equation, using the three-dimensional coordinates of the visual measurement and the load data measured by the sensor as observation vectors to optimally estimate the true state of the bottom mold system. The filter first predicts the attitude and load at the current moment based on the state at the previous moment, and then corrects the predicted values ​​using the current observation values. This effectively filters out high-frequency vibration noise and measurement outliers, outputting smooth and accurate displacement correction commands to the hydraulic proportional valve, achieving smooth and precise control of the bottom mold lifting process.

[0045] (3) Rolling optimization and valve control correction In each control cycle of the bottom formwork lifting operation, in order to balance the attitude tracking accuracy, the load balance of the lifting points and the smooth operation of the hydraulic actuator, and to avoid the control commands from exceeding the physical limits of the equipment or causing stress accumulation in the structure, it is necessary to construct an optimization target adapted to the working conditions and carry out calculations.

[0046] First, a quadratic objective function is constructed, which includes attitude tracking terms, load balancing terms, and control quantity suppression terms. The set dynamic weighting factors are then substituted into the objective function. The quadratic objective function... The specific expression is: ,in, For the predicted time domain length, it represents the number of time steps to predict the future; To control the time domain length, it represents the length of the optimized control sequence; This represents the total number of hydraulic lifters. for Time prediction The bottom formwork attitude error vector at time t represents the deviation between the actual attitude of the bottom formwork and the expected trajectory. This is a dynamic weighting matrix for attitude error, used to adjust the weights of attitude tracking error in the objective function. The elements can be dynamically adjusted according to control requirements to change the penalty intensity for different attitude error components. For the first One hanging point The load deviation rate at any given time reflects the degree of deviation between the force at the lifting point and the ideal force. For the first The load balance weighting coefficient for each lifting point, also known as the dynamic weighting factor, is used to balance the force distribution at each lifting point. It can be dynamically set according to the importance of the lifting point or the real-time load status. For the first The hydraulic proportional valve opening increment at each lifting point is the adjustment amount of the valve opening. The incremental weighting coefficient is used to control the drastic fluctuations in the control quantity and prevent the hydraulic proportional valve from operating too frequently.

[0047] The attitude tracking item The load balance term is used to minimize the weighted attitude error, i.e., the norm of the product of the bottom formwork attitude error vector and the dynamic weight matrix in the predicted time domain, to ensure that the bottom formwork attitude can follow the set trajectory. This is used to minimize load imbalance, i.e., the weighted sum of squares of the load deviation rates at each lifting point, to prevent overloading or underloading at individual lifting points. The control quantity suppression term... This is then used as a penalty function for the rate of change of the hydraulic proportional valve opening, through weighting coefficients. Limit the magnitude of the control increment to ensure smooth operation.

[0048] Subsequently, the objective function is iteratively solved using the Sequential Quadratic Programming (SQP) algorithm. The specific calculation process is as follows: First, physical constraints are introduced as inequality constraints, including the maximum lift rate. Maximum acceleration and the pressure saturation threshold of the hydraulic system Construct a system of constraint equations ,in The vector of control increment sequence to be solved contains the opening adjustment of all suspension points in the future control time domain.

[0049] At the current iteration point At this point, using the Lagrange function The objective function is approximated by a second-order Taylor expansion, and the constraints are linearized by a first-order linearization to construct a quadratic programming (QP) subproblem: in, The search direction indicates the direction in which the incremental sequence is adjusted. The Hessian matrix or its quasi-Newton approximation matrix (such as the BFGS matrix) of the objective function is used to approximate the second derivative information of the objective function, thereby accelerating the optimization convergence. This represents the gradient vector of the objective function at the current iteration point. Let be the Jacobian matrix of the constraint equation system, representing the sensitivity of the constraints to the control variables.

[0050] Solving this QP subproblem yields the search direction. The step size is determined by line search. Update control sequence This continues until the convergence condition is met, thereby obtaining the optimal control increment sequence in the future prediction time domain. .in, This represents the length of the prediction time domain, i.e., the number of steps the optimization algorithm takes to predict forward; to They represent from the current moment respectively From the beginning to the future The control increment sequence at each time step. This indicates the adjustment amount of the hydraulic proportional valve opening.

[0051] Secondly, the opening degree of the hydraulic proportional valve is corrected using the first control increment in this sequence, and a cooperative compensation strategy is executed in the process. When the first... When an abnormal stress occurs at a lifting point and its load deviation rate exceeds a preset stress relief threshold, the control system introduces a compliance control factor into the control loop of that lifting point. ( ), and correct its first control increment to This reduces the response speed of the lifting point, allowing it to lag slightly behind the command to release internal stress.

[0052] At the same time, in order to maintain overall stability while releasing stress, the control system calculates the first... The attitude deviation vector caused by deceleration at each suspension point The deviation vector is then allocated according to the dynamic weight factor ratio of the remaining normal suspension points to generate a compensation increment. The compensation increment This is superimposed on the first control increment of the remaining normal lifting points, so that the remaining normal lifting points, while maintaining the overall posture of the bottom formwork, share the burden of the first control increment. The load is unloaded from each lifting point, thereby achieving dynamic balance and safety control during the multi-point lifting process.

[0053] (4) Cooperative actions and system transformation After multiple rounds of optimization calculations and valve control corrections, the final control commands need to be converted into executable drive signals to enable coordinated operation of multiple lifting points.

[0054] First, a high-precision mapping from digital commands to hydraulic actions is implemented. The control system converts the calculated target displacement increments or speed commands for each lifting point into analog voltage signals via a digital-to-analog converter (D / A), or directly sends digital pulse signals to the electro-hydraulic servo valve drivers of each hydraulic lifter via a fieldbus. The servo valve, as the core actuator of the system, adjusts the valve core opening and direction based on the magnitude and polarity of the received electrical signal, thereby controlling the flow rate into the rod-side or rodless-side chamber of the hydraulic cylinder. In this process, a valve core hysteresis compensation algorithm and an oil temperature viscosity correction coefficient are introduced to eliminate the inherent nonlinear dead zone of hydraulic components, ensuring a strict linear correspondence between the electrical signal and the actual extension speed of the hydraulic cylinder piston rod, achieving micron-level synchronous action at multiple lifting points.

[0055] Next, multi-variable real-time closed-loop monitoring is implemented during the lifting process. During the dynamic process of lifting the bottom formwork to the design elevation, the control system collects real-time data on the actual displacement, cylinder pressure, and bottom formwork posture of each lifting point at millisecond intervals. The control system operates with dynamic synchronous control logic. If it detects that the actual speed of a lifting point deviates from the commanded speed due to load changes or mechanical friction, the controller immediately adjusts the opening of the servo valve at that point to compensate, ensuring that the bottom formwork remains stable throughout the lifting process and preventing tilting or torsional oscillations.

[0056] When the bottom formwork approaches the design elevation, the control system automatically switches to "fine-tuning mode." At this time, the lifting speed is limited to an extremely low creep rate (e.g., 0.5 mm / s). The control system continuously monitors two key indicators: first, the load deviation at each lifting point, i.e., the difference between the measured cable force and the theoretically allocated cable force; and second, the attitude error of the bottom formwork, i.e., the difference between the measured six-degree-of-freedom pose and the designed pose. Only when both indicators converge and stabilize within the preset threshold range (e.g., height difference less than 2 mm, cable force deviation less than 5%), is the bottom formwork determined to be in an ideal anchoring preparation state, allowing the next step of the operation to proceed.

[0057] Finally, the hydraulic interlock and system transition commands are executed. Once the above convergence conditions are met, the control system issues an interlock signal, driving the hydraulic lock (or balance valve) on the hydraulic lift to quickly actuate, cutting off the oil circuit and sealing the oil in the hydraulic cylinder, thereby mechanically locking the current spatial position of the bottom formwork and preventing settlement or displacement during the anchoring operation. Immediately afterwards, the control system triggers the anchoring command, alerting on-site personnel through audible and visual alarms or automatically guiding the anchoring mechanism to physically connect the bottom formwork support to the cable tower's embedded parts (e.g., by inserting steel pins or welding). After confirming that the anchoring point is fully stressed and the connection is reliable, the control system controls the hydraulic lift to slowly depressurize, allowing the weight of the bottom formwork to gradually and smoothly transfer from the suspended steel strands to the cable tower's embedded supports, completing the system transition from a "flexible suspension lifting state" to a "rigid support stress state," ensuring a safe and reliable structural stress switching.

[0058] Example 2 Please refer to Figure 4 This embodiment 2 provides a multi-point synchronous lifting control system for the bottom formwork of the cable tower's lower crossbeam suspension, including: The stiffness identification and pre-compensation unit is used to control each hydraulic lifting device to apply a small-amplitude sinusoidal disturbance signal to each lifting point before the lifting starts. It collects the force response and displacement response of each lifting point, calculates the actual dynamic stiffness coefficient of each lifting point under the current cable length, and constructs the stiffness matrix of the bottom formwork system. Based on the stiffness matrix and the preset horizontal attitude target of the bottom formwork, it calculates the initial pre-compensation displacement required for each lifting point to eliminate structural gaps and cable slack by solving the inverse kinematic equations, and controls each lifting point to execute the pre-compensation displacement so that the bottom formwork system is in a geometric equilibrium state without internal stress at the moment of lifting. A dual-loop and dynamic weighting unit is used to establish a dual-loop control model with the overall attitude error of the bottom mold as the outer loop and the load deviation of each lifting point as the inner loop. In the outer loop, the model predictive control algorithm is used to predict the displacement trajectory in the future time domain based on the current attitude. In the inner loop, a dynamic weighting factor is introduced, which has a positive correlation function with the real-time load deviation rate of each lifting point. When the load deviation rate of a certain lifting point increases, the weighting factor corresponding to that point is automatically increased, thereby increasing the priority of load following at that point and decreasing the priority of displacement synchronization in the control law. The rolling optimization and valve control correction unit is used to construct an objective function in each control cycle. The objective function aims to minimize the weighted attitude error and load imbalance. The optimal control increment sequence for each hydraulic lifter is solved by the rolling optimization algorithm. The opening of the hydraulic proportional valve is corrected by the first control increment in the sequence, so that when a lifting point is subjected to abnormal force, the lifting point is allowed to produce a small displacement hysteresis to release internal stress, while other normal lifting points maintain the stability of the overall attitude of the bottom mold through the compensation algorithm. The coordinated action and system conversion unit is used to convert the modified control commands into electrical signals to drive the coordinated action of each hydraulic lifter. During the lifting process, when the bottom formwork is lifted to the design elevation and the load deviation and attitude error of all lifting points converge to the threshold range allowed by the system conversion, the hydraulic lifters are automatically locked and the anchoring command of the bottom formwork and the cable tower embedded parts is triggered, thus completing the system conversion from the suspended lifting state to the supported stress state.

[0059] Example 3 This embodiment 3 also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it can implement any step of a multi-point synchronous lifting control method for a bottom formwork suspended by a cable tower beam.

[0060] The computer-readable storage medium may include various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0061] For a description of the computer-readable storage medium provided in this application, please refer to the above method embodiments; further details will not be repeated here.

[0062] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the synchronous lifting of multi-point bottom formwork of a cable tower with a suspended crossbeam, characterized in that, include: S1. Before the lifting starts, the control system controls each hydraulic lifting device to apply a small-amplitude sinusoidal wave disturbance signal to each lifting point, collects the force response and displacement response of each lifting point, calculates the actual dynamic stiffness coefficient of each lifting point under the current cable length, and constructs the stiffness matrix of the bottom formwork system. Based on the stiffness matrix and the preset horizontal attitude target of the bottom formwork, the initial pre-compensation displacement required for each lifting point to eliminate structural gaps and slack in the rigging is calculated by solving the inverse kinematic equations, and each lifting point is controlled to perform the pre-compensation displacement so that the bottom formwork system is in a geometric equilibrium state without internal stress at the moment of lifting. S2. Establish a dual closed-loop control model with the overall attitude error of the bottom mold as the outer loop and the load deviation of each lifting point as the inner loop; in the outer loop, the model predictive control algorithm is used to predict the displacement trajectory in the future time domain based on the current attitude; in the inner loop, a dynamic weighting factor is introduced, which has a positive correlation function with the real-time load deviation rate of each lifting point; when the load deviation rate of a certain lifting point increases, the weighting factor corresponding to that point is automatically increased, thereby increasing the priority of load following at that point and decreasing the priority of displacement synchronization in the control law; S3. Construct an objective function in each control cycle, the objective function being designed to minimize the weighted attitude error and load imbalance; The optimal control increment sequence for each hydraulic lifter is obtained by using a rolling optimization algorithm. The opening of the hydraulic proportional valve is corrected by using the first control increment in the sequence, so that when a lifting point is subjected to abnormal force, the lifting point is allowed to produce a small displacement lag to release internal stress, while other normal lifting points maintain the stability of the overall posture of the bottom mold through a compensation algorithm. S4. Convert the corrected control commands into electrical signals to drive each hydraulic lifter to move in coordination. During the lifting process, when the bottom formwork is lifted to the design elevation and the load deviation and attitude error of all lifting points converge to the threshold range allowed by the system conversion, the hydraulic lifters are automatically locked and the anchoring command of the bottom formwork and the cable tower embedded parts is triggered to complete the system conversion from the suspended lifting state to the supported force state.

2. The method for multi-point synchronous lifting control of the bottom formwork of a cable tower with a suspended crossbeam according to claim 1, characterized in that, When constructing the stiffness matrix of the bottom formwork system in S1, a nonlinear sag effect correction term for lifting the steel strand is introduced. The specific implementation steps include: A catenary mechanical model of steel strand is established, and the local tangential stiffness matrix of steel strand under the current tension state is derived based on the catenary equation. The tangential stiffness matrix includes material elastic stiffness terms and geometric nonlinear stiffness terms caused by self-weight sag. The local tangent stiffness matrix is ​​mapped to the global coordinate system by coordinate transformation to obtain the global stiffness matrix of the steel strand at each suspension point; Constructing nonlinear correction coefficients for height-wind speed coupling The coefficient is used to perform a weighted correction on the global stiffness matrix of the steel strand to characterize the lifting height. The sag effect caused by the change and the ambient wind speed The resulting change in aerodynamic stiffness; The corrected stiffness matrix of the steel strands at each suspension point is compared with the finite element structural stiffness matrix of the bottom formwork truss. Finite element analysis was performed to generate the overall stiffness matrix of the bottom formwork system. .

3. The method for multi-point synchronous lifting control of the bottom formwork of a cable tower with a suspended crossbeam according to claim 1, characterized in that, In S1, when calculating the initial pre-compensation displacement required to eliminate structural gaps and slack in the rigging at each suspension point by solving the inverse kinematic equations, the damped least squares (DLS) method is used to solve the generalized inverse of the Jacobian matrix to ensure the robustness and convergence of the calculation process. The specific calculation process is as follows: in, This represents the calculated initial pre-compensation displacement vector required for each lifting point. The Jacobian matrix of the system establishes the mapping relationship between the operating space and joint space of the bottom mold system, reflecting the current kinematic geometry of the system; The matrix representing the transpose of the Jacobian matrix; Let be the damping factor, a non-negative scalar parameter. The main purpose of introducing the damping factor is to improve the matrix. The condition number is used to prevent the calculation results from diverging when the system approaches a singular configuration; It is an identity matrix, and its dimensions are... The same, used to construct regularization terms; The preset attitude error target vector represents the deviation between the actual attitude of the current bottom mold system and the desired target attitude.

4. The method for multi-point synchronous lifting control of the bottom formwork of a cable tower with a suspended crossbeam according to claim 1, characterized in that, The dual closed-loop control model in S2 is constructed as a cascaded control structure that combines outer loop attitude control and inner loop load control. Among them, the outer ring serves as the position control ring, and its control objective is to eliminate the attitude error of the bottom mold system. This attitude error is obtained through a machine vision-based three-dimensional coordinate feedback mechanism. Specifically, high-precision visual targets are deployed at key monitoring points of the tower and the bottom mold. The spatial coordinate information of the targets is collected in real time through an industrial camera array. The current six-degree-of-freedom pose of the bottom mold is obtained through the attitude calculation method and compared with the preset target pose to generate an attitude deviation signal. The inner ring serves as a force control ring, with the control objective of eliminating load deviations between various lifting points to prevent structural tilting or instability caused by eccentric loading. The feedback signal for this load deviation originates from the data fusion of a pressure sensor and a hollow force sensor. Specifically, the pressure sensor is installed at the inlet of the hydraulic lifting cylinder to monitor the hydraulic thrust, while the hollow force sensor is connected in series at the anchoring end of the steel strand to directly measure the cable force. The data from the two sensors are redundant and mutually verified, together forming a highly reliable load feedback loop.

5. The method for multi-point synchronous lifting control of the bottom formwork of a cable tower with a suspended crossbeam according to claim 1, characterized in that, The objective function of the model predictive control algorithm in S2 not only includes minimizing the bottom mold attitude tracking error, but also explicitly introduces the flow saturation constraint and pressure safety boundary constraint of the hydraulic system, which are as follows: At each time step of the rolling optimization The controller predicts the flow demand of each hydraulic lifting cylinder in the future time domain based on the discrete state-space model of the system. ; During the rolling optimization process, the predicted traffic demand is monitored in real time. The maximum flow rate of the proportional valve is related to its physical limit parameter. The relationship between them; if the flow demand of one or more hanging points is predicted. The maximum flow rate limit of the proportional valve is about to be exceeded. This triggers the flow saturation constraint mechanism; at this point, the optimization solver will automatically adjust the control increment. The output of the flow is limited by adjusting the decision variables; To prevent system instability caused by flow rate limitations, a dynamic weighting strategy based on load priority is adopted: in the weighting matrix of the objective function, the flow rate supply weight for lifting points with larger loads is automatically increased to prioritize the stability of their operation and prevent the load from falling or tilting; at the same time, the weight coefficient of the displacement synchronization error term is dynamically reduced, allowing the system to experience slight displacement asynchrony for a short period of time in exchange for meeting the physical constraints. ; Furthermore, the pressure safety boundary constraint is used to prevent the hydraulic system from generating excessively high peak pressures during acceleration or braking; in the optimization calculation, the real-time pressure of the hydraulic circuit is considered. As a constraint condition, it is added to the set of inequality constraints, that is, it requires When the predicted pressure approaches the safety boundary, the control increment is also adjusted. This slows down the movement of the hydraulic cylinder, thereby smoothing out pressure fluctuations.

6. The method for multi-point synchronous lifting control of the bottom formwork of a cable tower with a suspended crossbeam according to claim 1, characterized in that, The calculation formula for the dynamic weighting factor in S2 is set to an exponential decay function form, and the specific expression is as follows: in, Representing the The first hanging point The real-time load deviation within each control cycle is the absolute value of the difference between the current actual measured load and the ideal equilibrium load. A preset load imbalance threshold is set, which defines the safe range of load deviation allowed by the system. This is the gain coefficient, used to adjust the sensitivity of the weighting factor to changes in load deviation. The larger the value, the faster the weight increases with the deviation.

7. The method for multi-point synchronous lifting control of the bottom formwork of a cable tower with a suspended crossbeam according to claim 1, characterized in that, In step S3, the optimal control increment sequence for each hydraulic lifter is solved using a rolling optimization algorithm, specifically including: First, a quadratic objective function is constructed, which includes attitude tracking terms, load balancing terms, and control quantity suppression terms. ;in, The current sampling time is indicated; the attitude tracking term is used to measure the deviation between the bottom mold attitude and the set trajectory, and is defined as the norm of the product of the bottom mold attitude error vector and the dynamic weight matrix in the prediction time domain; the load balancing term is used to balance the force on each lifting point, and is defined as the weighted sum of squares of the load deviation rates of each lifting point; the control quantity suppression term is used to prevent the hydraulic proportional valve from operating too frequently, and is defined as a penalty function for the rate of change of the hydraulic proportional valve opening; when solving this objective function, physical constraints of the hydraulic lifter are introduced as inequality constraints, including the maximum lifting speed, the maximum acceleration, and the pressure saturation threshold of the hydraulic system, to ensure that the calculated control commands meet the physical execution limits of the equipment; Subsequently, the Sequential Quadratic Programming (SQP) algorithm is used to iteratively solve the constrained quadratic objective function to calculate the optimal control increment sequence in the future prediction time domain. ;in, This represents the length of the prediction time domain, i.e., the number of steps the optimization algorithm takes to predict forward; to They represent from the current moment respectively From the beginning to the future The control increment sequence at each time step. This indicates the adjustment amount of the hydraulic proportional valve opening.

8. The method for multi-point synchronous lifting control of the bottom formwork of a cable tower with a suspended crossbeam according to claim 1, characterized in that, In step S3, the opening degree of the hydraulic proportional valve is corrected using the first control increment in the sequence, specifically by implementing the following collaborative compensation strategy: When the first When an abnormal stress occurs at a single lifting point and its load deviation rate exceeds the preset stress relief threshold, The lifting point is numbered, and a compliant control factor is introduced into the control loop of that lifting point in the control system. The first control increment was revised to This correction reduces the response speed of the suspension point, allowing it to produce a small displacement hysteresis to release internal stress. Meanwhile, in order to offset the impact of the aforementioned lag on the overall attitude, the first... The attitude deviation vector caused by deceleration at each suspension point and the deviation vector The compensation increment is generated by allocating the compensation based on the dynamic weight factor ratio of the remaining normal lifting points. ; this compensation increment This is superimposed on the first control increment of the remaining normal lifting points, so that the remaining normal lifting points, while maintaining the overall posture of the bottom formwork, share the burden of the first control increment. The load was unloaded from each lifting point.

9. A multi-point synchronous lifting control system for a suspended bottom formwork of a cable tower, characterized in that, include: The stiffness identification and pre-compensation unit is used to control each hydraulic lifting device to apply a small-amplitude sinusoidal disturbance signal to each lifting point before the lifting starts, collect the force response and displacement response of each lifting point, calculate the actual dynamic stiffness coefficient of each lifting point under the current cable length, and construct the stiffness matrix of the bottom formwork system. Based on the stiffness matrix and the preset horizontal attitude target of the bottom formwork, the initial pre-compensation displacement required for each lifting point to eliminate structural gaps and slack in the rigging is calculated by solving the inverse kinematic equations, and each lifting point is controlled to perform the pre-compensation displacement so that the bottom formwork system is in a geometric equilibrium state without internal stress at the moment of lifting. A dual-loop and dynamic weighting unit is used to establish a dual-loop control model with the overall attitude error of the bottom mold as the outer loop and the load deviation of each lifting point as the inner loop. In the outer loop, the model predictive control algorithm is used to predict the displacement trajectory in the future time domain based on the current attitude. In the inner loop, a dynamic weighting factor is introduced, which has a positive correlation function with the real-time load deviation rate of each lifting point. When the load deviation rate of a certain lifting point increases, the weighting factor corresponding to that point is automatically increased, thereby increasing the priority of load following at that point and decreasing the priority of displacement synchronization in the control law. A rolling optimization and valve-controlled correction unit is used to construct an objective function in each control cycle, the objective function being designed to minimize the weighted attitude error and load imbalance; The optimal control increment sequence for each hydraulic lifter is obtained by using a rolling optimization algorithm. The opening of the hydraulic proportional valve is corrected by using the first control increment in the sequence, so that when a lifting point is subjected to abnormal force, the lifting point is allowed to produce a small displacement lag to release internal stress, while other normal lifting points maintain the stability of the overall posture of the bottom mold through a compensation algorithm. The coordinated action and system conversion unit is used to convert the modified control commands into electrical signals to drive the coordinated action of each hydraulic lifter. During the lifting process, when the bottom formwork is lifted to the design elevation and the load deviation and attitude error of all lifting points converge to the threshold range allowed by the system conversion, the hydraulic lifters are automatically locked and the anchoring command of the bottom formwork and the cable tower embedded parts is triggered, thus completing the system conversion from the suspended lifting state to the supported stress state.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The computer program is executed by a processor as described in any one of claims 1-8: a multi-point synchronous lifting control method for a suspended bottom formwork of a cable tower.

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