A cooperative control method for double-machine lifting of a large-span net rack

Abstract

The present application belongs to the technical field of double-machine lifting control of net rack, and specifically discloses a cooperative control method for double-machine lifting of large-span net rack, which divides the lifting stage by the whole lifting process, presets the lifting point position, crane station and target form of each stage, constructs a phased cooperative control framework, judges the synchronous deviation in each lifting stage execution, and adopts the double-machine hook height difference, double-machine load weight difference, and the virtual horizontal inclination of the net rack in the direction of the two lifting points and the vertical direction when judging the synchronous deviation, to construct a multi-dimensional synchronous deviation state index. The index not only reflects the output state of the lifting equipment, but also represents the attitude response of the net rack body in the three-dimensional space, can comprehensively and accurately identify the real out-of-step state, and when detecting the deviation, implements the targeted adjustment strategy, triggers the orderly switching of the lifting stage after the deviation is suppressed and the structure state is stable, and effectively avoids the problems of over-regulation or insufficient response caused by unified control parameters.

Description

Technical Field

[0001] This invention belongs to the field of control technology for dual-machine lifting of space frame structures, and specifically discloses a collaborative control method for dual-machine lifting of large-span space frames. Background Technology

[0002] Large-span space frame structures are widely used in large public buildings such as stadiums, airports, and exhibition halls. These structures are typically characterized by large component spans, heavy individual weights, and high installation precision requirements. Therefore, during construction and hoisting, a single crane is often insufficient to meet the load and dimensional requirements, making dual-crane hoisting the primary hoisting solution.

[0003] In dual-crane lifting operations, ensuring the synchronization of the two cranes' movements is the core key to ensuring lifting safety and accuracy. If the movements are out of sync, it can easily lead to excessive internal forces and deformation in the space frame structure, which may affect the installation accuracy or even cause permanent structural damage.

[0004] Several methods and systems have emerged in the prior art aimed at improving the coordination of dual-machine lifting. For example, Chinese invention patent publication number CN119858862A proposes a coordinated control method and safety monitoring system for dual-machine lifting of large-span steel structures. By deploying multi-source sensors at the hook and key structural nodes, real-time monitoring data is fused, and deviation identification of lifting path planning and digital twin drive is achieved by combining BIM model. Its control logic is based on nonlinear programming to solve for the optimal weight ratio and uses fuzzy PID algorithm for synchronous adjustment.

[0005] While the above-mentioned solutions improve the controllability of the hoisting process to some extent, they still have the following limitations: First, the control model of the above-mentioned solutions is based on a static or quasi-steady-state optimization model constructed under relatively fixed hoisting conditions. This model fails to fully consider the abrupt changes in working conditions caused by contact or detachment between the space frame and concrete supports, steel column supports, etc., during the entire continuous lifting path from ground assembly to aerial placement. The boundary conditions, stress states, and control objectives of the space frame differ significantly at different stages, making it difficult for a unified control strategy to achieve optimal results in all stages.

[0006] Secondly, the above scheme mainly relies on the load difference between the two machines and the absolute position based on laser ranging as the basis for synchronous evaluation and adjustment. It lacks consideration of the spatial attitude of the space frame itself. The tilt of the space frame during the hoisting process is a three-dimensional spatial problem. Relying solely on the load difference or displacement difference in one direction is insufficient to fully and accurately reflect its true out-of-step state, thus restricting the accuracy and reliability of collaborative control. Summary of the Invention

[0007] Therefore, one objective of this application is to provide a collaborative control method for the dual-machine lifting of large-span space frames, which can perform refined collaborative control of the entire process and stages of the lifting of large-span space frames, effectively solving the problems raised in the background art.

[0008] The purpose of this invention can be achieved through the following technical solution: a collaborative control method for double-machine lifting of a large-span space frame, including the following steps: (1) before lifting, the overall lifting process is divided into multiple continuous lifting stages according to the spatial relationship between the space frame and the support, and the corresponding lifting point position, crane station position and stage target shape are preset for each stage.

[0009] (2) During the hoisting process, the hook height, boom elevation angle, load weight and planar position data of the two cranes are obtained in real time.

[0010] (3) Calculate the difference in load weight between the two machines based on real-time data, and calculate the virtual horizontal tilt angle of the grid structure in the direction of the line connecting the two lifting points by combining the hook height, boom elevation angle and planar position through geometric projection relationship, so as to construct the synchronization state index.

[0011] (4) Use the synchronous status indicators of the current lifting stage to judge the deviation.

[0012] (5) When there is a deviation in the evaluation, an adjustment command is generated by selecting one or a combination of the speed fine-tuning command based on the load balancing rule and the height compensation command based on the attitude correction rule according to the current lifting stage to adjust the action.

[0013] Combining all the above technical solutions, the positive effects of this invention are as follows: 1. This invention divides the entire hoisting process into lifting stages, presets the lifting point positions, crane positions and target shapes for each stage, and constructs a staged collaborative control framework. Synchronous deviation evaluation is performed during the execution of each lifting stage. When a deviation is detected, a targeted adjustment strategy is implemented. After the deviation is suppressed and the structural state is stable, the orderly switching of the lifting stage is triggered, which effectively avoids over-adjustment or insufficient response caused by unified control parameters, thereby significantly reducing the risk of structural damage.

[0014] 2. When evaluating synchronization deviation at each lifting stage, this invention comprehensively adopts the weight difference of the loads of the two machines and the virtual horizontal tilt angle of the space frame in the direction of the line connecting the two lifting points to construct a multi-dimensional synchronization state index. This not only reflects the output state of the lifting equipment, but also directly characterizes the rigid body attitude response of the space frame body in three-dimensional space. It effectively integrates the dual information of force and form, and can comprehensively and accurately identify the real loss of synchronization state, providing a reliable basis for precise and safe collaborative control.

[0015] 3. When deviations occur during the lifting stage, this invention intelligently selects a single or combined adjustment strategy from speed fine-tuning commands based on load balancing rules and height compensation commands based on attitude correction rules, according to the deviation status and the control priority of the current lifting stage. This can effectively meet the control requirements of the structure at different lifting stages, making the adjustment process more targeted and stable, thereby achieving high-precision attitude control while ensuring structural safety. Attached Figure Description

[0016] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0017] Figure 1 This is a diagram illustrating the implementation steps of the method of the present invention.

[0018] Figure 2 This is a flowchart illustrating the implementation process of using the synchronization status index of the current lifting stage to evaluate deviations in this invention.

[0019] Figure 3 This is a schematic diagram illustrating the use of speed fine-tuning instructions based on load balancing rules in this invention.

[0020] Figure 4 This is a schematic diagram illustrating the use of a height compensation command based on attitude correction rules in this invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] See Figure 1 As shown, the present invention proposes a collaborative control method for dual-machine lifting of a large-span space frame, including the following steps: (1) Before lifting, the overall lifting process is divided into multiple continuous lifting stages according to the spatial relationship between the space frame and the support, and the corresponding lifting point position, crane station position and stage target shape are preset for each stage.

[0023] For large-span space frames, the hoisting path is long and the working conditions are complex. The process from ground assembly to aerial placement involves key milestones such as lifting off the ground, detachment from temporary supports, crossing concrete or steel supports, high-level translation, and final support placement. The support state and load transfer path change significantly at each stage, resulting in vastly different structural stiffness, stress distribution, and sensitivity to synchronous deviations. A unified control strategy cannot adequately address all working conditions. Therefore, it is necessary to divide the hoisting process into several lifting stages to achieve phased, refined, and adaptive collaborative control.

[0024] In some embodiments, the process of dividing the overall hoisting process into multiple consecutive lifting stages includes: in the lifting path of the space frame from the ground assembly state to the final installation position, the key nodes where the space frame structure contacts or separates from the concrete supports and steel column supports are used as the working condition demarcation points.

[0025] The concrete supports and steel column supports mentioned above refer to the vertical load-bearing support components upon which the large-span space frame structure relies in its final installation state. Together, they constitute the design boundary constraints of the space frame, bearing all vertical loads and transferring them to the lower foundation after the structure is in place.

[0026] Understandably, the critical point where the space frame contacts or detaches from the aforementioned supports is chosen as the dividing point between working conditions because when the space frame contacts the supports, the space frame nodes that were originally free ends become constrained supports, part of the load is borne by the supports, the load on the lifting points decreases accordingly, and the structure transitions from a fully suspended state to a mixed stress state of partial support and partial lifting; when detaching from the supports, the support reaction force becomes zero, all loads are instantly transferred to the lifting point system, the degree of freedom of constraint increases sharply, and the structural stiffness matrix and internal force redistribution path change significantly. Dividing the working conditions by such mechanical state transition points can accurately reflect the actual behavior of the structure under different stress modes.

[0027] Based on the spatial locations corresponding to these dividing points, the continuous lifting path is divided into several orderly and interconnected lifting stages.

[0028] Applying the above division logic to an example, a complete lifting process can usually be divided into the following five typical lifting stages: Ground assembly and preloading stage: The space frame is assembled on the ground, the slings are initially tensioned, but have not yet detached from the temporary frame. At this time, the supports are not under stress, and the load is borne by the temporary frame.

[0029] Lifting off the ground and detachment from the support frame: The crane slowly lifts the structure, and the space frame gradually detaches from the ground support frame. After this, the structure enters a fully lifted state, and the entire load is borne by the lifting points.

[0030] Crossing the lower support structure stage: During the lifting of the space frame, it is necessary to cross the already constructed concrete piers or steel columns.

[0031] High-level translation and attitude adjustment stage: The grid structure has completely detached from all lower obstacles and is in a state of high-altitude hovering or horizontal fine-tuning.

[0032] Precise placement of supports: The space frame slowly descends, and the support nodes are aligned with the embedded parts.

[0033] Based on the division of lifting stages, the corresponding lifting point positions, crane positions, and stage target shapes are preset for each stage.

[0034] The lifting points are key load-bearing nodes on the space frame structure, specifically designed and verified according to the lifting conditions. They are used to connect lifting slings such as hooks and are usually located at the intersection of the upper chord or web members. They possess sufficient local bearing capacity and structural stiffness to ensure effective load transfer and maintain the overall stability of the structure during lifting. The location of the lifting points is determined by the initial space frame lifting plan.

[0035] Crane positioning refers to the comprehensive configuration of working parameters for two cranes at the construction site, including a combination of key parameters such as planar positioning coordinates, boom length, operating radius, slewing angle, and lifting height. This configuration aims to ensure that the cranes have sufficient lifting capacity, operating coverage, and safe operating space at each lifting stage, while avoiding interference with the space frame structure, support system, or surrounding obstacles. The lifting point positions are also determined by the initial space frame lifting plan.

[0036] The target form refers to the ideal spatial geometric configuration and mechanical equilibrium state that the space frame should achieve during the lifting phase. Specifically, it encompasses the allowable limits for balanced load distribution between the two machines, the safety limits for the virtual horizontal tilt angle of the space frame along the line connecting the lifting points, and the design spatial coordinates of key control nodes such as support connection points. This form embodies the control benchmark and safety boundary requirements of this phase and serves as the reference for judging synchronous deviations and generating adjustment commands. The target form is also determined by the space frame lifting scheme.

[0037] (2) During the hoisting process, the hook height, boom elevation angle, load weight and planar position data of the two cranes are obtained in real time.

[0038] In the preferred implementation of the above scheme, the process of acquiring real-time data during the hoisting process is as follows: an absolute encoder is installed at the hook pulley block of each crane to measure the hook height in real time.

[0039] A dynamic tilt sensor is installed at the base pin of each crane boom to measure the boom elevation angle in real time.

[0040] A side-pressure tension sensor is installed at the fixed end of the lifting wire rope of each crane to measure the load weight in real time.

[0041] Differential GPS positioning devices are installed at the center of the slewing platform of each crane to obtain the crane's planar position in real time.

[0042] It should be noted that the hook height provides the absolute elevation reference of the hook in the vertical direction.

[0043] The boom elevation angle is the angle between the boom and the horizontal plane. Combined with the boom length, the theoretical spatial coordinates of the hook can be geometrically inverted.

[0044] The load capacity is the actual lifting load currently borne by each crane, and it serves as the basis for judging the load balance.

[0045] The crane's planar position refers to the two-dimensional coordinates of the crane's rotation center in the construction coordinate system, used to determine the projected distance between two lifting points in the horizontal plane.

[0046] The data acquired in real time during the hoisting process provides a foundation for the subsequent construction of synchronization deviation status indicators, thus providing a state awareness basis.

[0047] (3) Calculate the difference in load weight between the two machines based on real-time data, and calculate the virtual horizontal tilt angle of the grid structure in the direction of the line connecting the two lifting points by combining the hook height, boom elevation angle and planar position through geometric projection relationship, so as to construct the synchronization state index.

[0048] Specifically, the virtual horizontal tilt angle is obtained through the following process: a three-dimensional engineering measurement coordinate system is established at the construction site, usually with the design axis of the grid structure as the reference, using an orthogonal rectangular coordinate system. Under this coordinate system, the initial coordinates of the rotation centers of the two cranes are determined by calibrating a total station.

[0049] The initial coordinates of the rotation centers of the two cranes are combined with the boom elevation angle and rotation azimuth angle obtained by the tilt sensors installed on the cranes. The rotation direction angle is provided by the rotary encoder or electronic compass on the crane rotation platform, which represents the pointing angle of the boom in the horizontal plane. The hook height data is also fused, and the three-dimensional spatial coordinates of the hook center in the three-dimensional engineering measurement coordinate system are calculated by using the boom geometric length and forward kinematics model.

[0050] Given that the crane boom can be considered as a multi-link mechanism consisting of a slewing platform, a luffing mechanism, and a telescopic boom, and knowing the coordinates of the slewing center, azimuth angle, boom elevation angle, boom geometric length, and hook height, the three-dimensional coordinates of the hook in the engineering coordinate system can be inverted using a forward kinematics model that transforms the geometric relationship from spherical coordinates to rectangular coordinates.

[0051] Applying the above description to the example, the forward kinematics model ,in Indicates the coordinates of the center of rotation. Indicates the boom elevation angle. Indicates the azimuth angle. Indicates the geometric length of the boom. This represents the additional elevation of the hook relative to the end of the boom. The three-dimensional coordinates of the hook in the engineering coordinate system obtained under this model inversion are: .

[0052] Based on the spatial coordinates of the hook and the length of the sling, the actual spatial positions of the sling and the lifting point are estimated, and a spatial mapping relationship from the hook to the lifting point is established under the assumption of a rigid connection.

[0053] Secondly, if the slings are taut and do not exhibit significant elastic deformation or swaying during the lifting of the space frame, they can be simplified as rigid members. Given the coordinates of the hooks and the length of the slings, the spatial position of the lifting points on the space frame can be estimated along the direction of the slings.

[0054] For example, the spatial mapping from the hook to the lifting point under the assumption of a rigid connection is as follows: ,in, This represents the spatial coordinates of the hook in the engineering coordinate system. This represents the spatial coordinates of the suspension points in the same coordinate system under the assumption of a rigid connection. Indicates the length of the sling. This represents the unit direction vector of the sling. If oscillation is ignored, That is, the lifting point is directly below the hook.

[0055] Under the spatial mapping relationship, the three-dimensional coordinates corresponding to the two suspension points are obtained, and the line vector connecting the two suspension points is constructed using them. Then, the projection vector of the line vector on the horizontal plane is calculated.

[0056] Using the length of the projection vector and the elevation difference between the two suspension points, the virtual horizontal tilt angle of the space frame along the line connecting the suspension points is calculated using the arctangent function.

[0057] In a specific embodiment, the spatial coordinates of two lifting points are given. , Construct connecting vectors Its projection vector on the horizontal plane is At this time, the virtual horizontal tilt angle of the space frame along the line connecting the suspension points .

[0058] As a supplement to the above operations, the reason why the lifting point coordinates are not directly obtained as attitude criteria in the constructed coordinate system, but are indirectly calculated through kinematic inversion and spatial mapping, is mainly because: the lifting points of the space frame, as key structural nodes, are usually located tens of meters in the air and continuously move dynamically during the lifting process. It is impossible to deploy fixed high-precision measuring equipment on them, thus lacking a real-time means to directly obtain their absolute spatial coordinates. Therefore, it is necessary to rely on stable measurable equipment end parameters, including hook elevation, boom elevation angle, slewing azimuth angle, and crane planar position, combined with the boom geometric model to perform forward kinematics and invert the hook spatial coordinates.

[0059] By utilizing the prior information that the sling length is known, a spatial mapping relationship between the hook and the lifting point is established under the assumption of rigid slings. After obtaining the coordinates of the lifting point through this mapping, the interference introduced by the movement of the crane equipment can be effectively eliminated. Starting from the geometric configuration of the structure itself, the virtual horizontal tilt angle can be accurately calculated, thereby achieving reliable perception of the true rigid body attitude of the space frame.

[0060] The virtual horizontal tilt angle calculated above represents the spatial tilt state of the space frame as a rigid body relative to the ideal horizontal reference plane under the current suspension point arrangement conditions. It is an indicator reflecting the overall attitude deviation of the structure.

[0061] (4) Use the synchronous status indicators of the current lifting stage to judge the deviation.

[0062] See Figure 2 As shown, the specific implementation process of the above steps is as follows: The real-time calculated difference in the load weight of the two machines is compared with the preset load balance allowable limit value of the current lifting stage to evaluate whether the load distribution during lifting is within the design allowable balance range.

[0063] The virtual horizontal tilt angle calculated in real time is compared with the horizontal tilt angle safety limit set at the current lifting stage to assess whether the spatial attitude of the space frame during the lifting process meets the structural safety requirements.

[0064] When either the difference in load weight between the two machines or the virtual horizontal tilt angle exceeds the corresponding limit, a synchronization deviation is judged.

[0065] This invention integrates a dual-verification logic of mechanical balance and spatial geometric consistency in its evaluation mechanism for the synchronicity of dual-machine lifting. Among these, load balance is a fundamental prerequisite for ensuring structural safety. As a typical statically indeterminate spatial structure, the distribution of internal forces in the members of a space frame is highly sensitive to the load height at the lifting points. If the load of the two machines is severely unbalanced, it will cause local members to exceed their stress limits, nodes to experience abnormal stress, and may even lead to member buckling or connection failure.

[0066] Spatial geometric consistency refers to the degree of conformity between the overall rigid body configuration of the space frame and the preset target shape in three-dimensional space during the lifting process. When the virtual horizontal tilt angle exceeds the limit, it indicates that the actual spatial posture of the space frame has deviated from the ideal horizontal state, and the structure may undergo asymmetrical deformation or torsion. Even if the hook movement seems to be synchronized, there is still a risk of deformation inconsistency.

[0067] Within this framework, the load difference characterizes the unbalanced state of forces, while the virtual horizontal tilt angle reflects the inconsistency of form. In contrast, traditional methods rely solely on the absolute values ​​of hook height difference or load difference for monitoring, making it difficult to identify hidden risks where equipment actions appear synchronized but the structure itself has already undergone harmful deformation, resulting in significant safety blind spots.

[0068] (5) When there is a deviation in the evaluation, the adjustment command is generated by selecting one or a combination of the speed fine-tuning command based on the load balancing rule and the height compensation command based on the attitude correction rule according to the current lifting stage.

[0069] As a way to achieve the above solution, the speed fine-tuning instruction process based on the load balancing rule includes: comparing the current load weight of the two cranes, and determining the crane with the higher load weight as the target adjustment crane, because the crane with the heavier load bears a load that exceeds the balanced distribution ratio, which poses a risk of unbalanced load.

[0070] The load imbalance degree is defined as the ratio of the current load weight difference to the current load balance tolerance limit during the lifting phase.

[0071] The load imbalance measure quantifies the relative degree to which the current load distribution deviates from the design equilibrium state. The greater the load imbalance, the more unbalanced the load distribution between the two machines.

[0072] Based on the load imbalance, the speed adjustment step size corresponding to the corresponding load imbalance is matched from the established speed adjustment step size mapping sequence.

[0073] In further innovative implementation, the speed adjustment step size mapping sequence includes the following: determining the speed adjustment range based on the rated parameters of the motor in the hoisting control system.

[0074] The aforementioned speed adjustment range reflects the speed adjustment limit that the crane actuator can achieve under physical and electrical constraints. This range can be obtained directly from the motor technical manual or equipment performance manual.

[0075] Considering that a heavy load on one side of the crane indicates excessive load on that side, appropriately reducing the lifting speed of the crane on the heavier side can slightly shift the structural center of gravity towards the lighter side, thus transferring the load to the lighter side. Therefore, when the load is unbalanced, speed regulation can be used to actively suppress the unbalanced load. However, crane speed regulation depends on the execution capability of its drive motor. This regulation is not unconstrained; its feasible range is strictly limited by the speed adjustment range defined by the motor's rated parameters such as rated speed and speed ratio. This reflects the fundamental principle in control system design that the execution capability matches the control commands, avoiding motor overload due to exceeding the limits.

[0076] By utilizing the speed adjustment range and control accuracy requirements, the minimum and maximum values ​​of the speed adjustment step size are determined.

[0077] Using the minimum speed adjustment step size as the increment, several discrete, graded, and progressively increasing speed adjustment step sizes are generated between the minimum speed adjustment step size and the maximum speed adjustment step size.

[0078] The aforementioned control accuracy requirement refers to the technical indicators required by the hoisting control system for the sensitivity and stability of the load balancing adjustment process. This requirement is specifically reflected in the upper and lower limits of the speed adjustment range, and is quantitatively characterized by the minimum and maximum allowable speed adjustment step size. These can be obtained from the hoisting equipment technical specifications. The minimum speed adjustment step size reflects the speed adjustment amount corresponding to the minimum perceptible load change, while the maximum speed adjustment step size is limited by the physical characteristics of the low stiffness of the large-span space frame structure. If the single speed change is too large, it will induce significant structural swaying, sling swing, or instantaneous impact load, thereby threatening installation accuracy and construction safety.

[0079] In a specific example, assuming the speed adjustment range is [0, 20 mm / s], the control accuracy requirements include a minimum speed adjustment step of 2 mm / s and a maximum speed adjustment step of 10 mm / s.

[0080] Compare whether the maximum speed adjustment step size in the control accuracy falls within the speed adjustment range. In this example, the maximum speed adjustment step size falls within the speed adjustment range. Then, the control accuracy is used as the upper and lower limit constraints for the speed adjustment step size. The resulting speed adjustment step sizes are 2mm / s, 4mm / s, 6mm / s, 8mm / s, and 10mm / s, respectively.

[0081] As another example, assuming the speed adjustment range is [0, 20 mm / s], the control accuracy requirements include a minimum speed adjustment step of 2 mm / s and a maximum speed adjustment step of 30 mm / s.

[0082] At this point, the maximum speed adjustment step size is higher than the upper limit of the speed adjustment range, exceeding the equipment's capacity. Therefore, the upper limit speed of the speed adjustment range and the minimum speed adjustment step size in the control accuracy are used as the upper and lower limit constraints of the speed adjustment step size. The speed adjustment step sizes are divided into 2mm / s, 4mm / s, 6mm / s, 8mm / s, 10mm / s, 12mm / s, 14mm / s, 16mm / s, 18mm / s, and 20mm / s, respectively.

[0083] By conducting simulation tests on the grid structure under different load imbalance conditions, the system response was measured, thereby calibrating the correspondence between the load imbalance degree and the required speed adjustment, and then establishing an empirical mapping sequence between it and the speed adjustment step size.

[0084] In one specific embodiment, the process of calibrating the correspondence between load imbalance and required speed adjustment is as follows: First, a series of controllable initial off-center load states are preset in the simulation environment, such as: load imbalance conditions: 0.2, 0.4, 0.6, 0.8, 1.0, 1.2.

[0085] Under each load imbalance condition, one side of the crane is intentionally set to bear more load.

[0086] Secondly, for each imbalance condition, multiple candidate speed adjustment step sizes are tried in sequence, and the relief status of the load imbalance is recorded.

[0087] Furthermore, for each imbalance condition, the minimum speed adjustment step size that can eliminate the load imbalance within a specified time without causing structural swaying or sudden tilt angle changes is selected as the calibration result for the relief state of the load imbalance.

[0088] Finally, the calibration results for all operating conditions are summarized into a speed adjustment step size mapping sequence.

[0089] Based on the matched speed adjustment step size, a micro-increase command is generated to adjust the descent speed of the crane for the target. That is, a small negative speed increment is superimposed on the current lifting speed, which is equivalent to a slight deceleration or slow descent, prompting the load between the two machines to be redistributed and gradually restored to a balanced state.

[0090] This invention proposes a speed fine-tuning mechanism for load imbalance, which achieves proactive, precise, and stable intervention in the dual-machine lifting process through a logic chain of state perception, imbalance quantification, and adaptive adjustment.

[0091] As another possible way to implement the above scheme, the process of generating height compensation instructions based on attitude correction rules includes: judging the tilt direction of the structure according to the state of the virtual horizontal tilt angle of the space frame relative to the horizontal tilt angle safety limit, and then determining the target hook that needs to be lifted or lowered.

[0092] In practical implementation, assuming that the two lifting points of the space frame are numbered in left-right order, the left lifting point corresponds to hook A, and the right lifting point corresponds to hook B. The virtual horizontal tilt angle is defined as the tilt angle of the line connecting left to right relative to the ideal horizontal plane. When the virtual horizontal tilt angle of the space frame is greater than the safety limit of the positive horizontal tilt angle, it indicates that the left lifting point is high and the right lifting point is low, and the space frame is tilted with the left side higher than the right side. In order to restore the horizontal attitude, it is necessary to perform a lowering operation on the left hook and a raising operation on the right hook at the same time to reduce the tilt angle.

[0093] When the virtual horizontal tilt angle of the space frame is lower than the negative horizontal tilt angle safety limit, it indicates that the right lifting point is high and the left lifting point is low, and the space frame is tilted with the right side higher than the left side. At this time, the right hook should be lowered and the left hook should be raised to achieve attitude correction.

[0094] Based on the tilt angle residual between the virtual horizontal tilt angle and the horizontal tilt angle safety limit, and combined with the projection distance of the two suspension points in the horizontal plane, the height compensation required to eliminate the residual is calculated using the linearized trigonometric relationship under the small angle approximation.

[0095] Understandably, given that the residual tilt angle between the measured virtual tilt angle and the safe limit of the tilt angle is usually small, a small angle approximation can be reasonably used. The geometric relationships are linearized. Under this premise, the total height compensation required to eliminate the tilt angle residual is determined. The following linearized trigonometric relationship can be used for calculation: ,in , Indicates the virtual horizontal tilt angle. Indicates the marked horizontal tilt angle safety limit. This represents the projected distance between the two suspension points in the horizontal plane. This indicates the amount of height compensation.

[0096] The height compensation is decomposed into the relative displacement that the two hooks need to move, and the two are in opposite directions. The distribution ratio is set according to the inverse relationship between the actual measured load weights of the two machines, that is... ,in , These represent the relative displacements that the two hooks need to move. , The values ​​represent the measured load weights of the two cranes, respectively. This strategy ensures that the side with the heavier load bears less displacement, thus avoiding further exacerbation of load unevenness during the adjustment process.

[0097] The displacement amount of the height compensation based on the comprehensive displacement direction attitude correction rules is used to generate a dual-machine height compensation command that includes both displacement direction and displacement amount.

[0098] This invention proposes a height compensation method for attitude correction rules, which organically integrates geometric attitude error identification, structural stress state feedback and cooperative motion planning. This not only effectively corrects the tilt of the space frame, but also takes into account the load balance.

[0099] See Figure 3 and Figure 4 Furthermore, select one or a combination of adjustment instructions to perform the following actions: when a deviation is judged solely by the difference in load weight between the two machines exceeding the corresponding limit, select a speed fine-tuning instruction based on load balancing rules.

[0100] When a deviation is judged solely by the virtual horizontal tilt angle exceeding the corresponding limit, a height compensation command based on attitude correction rules is selected.

[0101] When a deviation is judged by the weight difference of the dual-machine load and the virtual horizontal tilt angle exceeding the corresponding limit, if the current lifting stage is in the lifting stage above the ground or in the stage of passing through the supporting structure, the structure is extremely sensitive to local eccentric loads, which can easily cause overstress in the members or collision with the supports. In this case, the speed fine-tuning command based on the load balance rule should be selected first. After the load difference falls back to the allowable limit, the attitude state should be evaluated. If the virtual horizontal tilt angle still exceeds the corresponding limit, the height compensation command based on the attitude correction rule should be added.

[0102] If the current lifting stage is in the high-level translation and attitude adjustment stage or the support precision positioning stage, the structure has already been removed from the temporary support, and the requirements for spatial attitude accuracy are extremely high. Attitude control becomes the primary goal, and the load distribution is relatively stable. The height compensation command based on the attitude correction rule is selected first. After the virtual horizontal tilt angle stabilizes within the allowable limit, the load weight difference is then monitored. If the load weight difference still exceeds the corresponding limit, the speed fine-tuning command based on the load balancing rule is added.

[0103] When selecting adjustment strategies in the presence of synchronization deviations, this invention fully considers the differences in structural sensitivity and the priority of control objectives at different construction stages, effectively decoupling the coupling interference between force and form, and ensuring structural safety while also taking into account installation accuracy.

[0104] (6) When transitioning from the current lifting stage to the next lifting stage, a stage switch is performed, specifically as follows: check whether the morphological parameters of the grid structure in the current lifting stage have reached its target shape.

[0105] Once the target state is reached, a stage switching command is sent to the control system.

[0106] The control system guides the crane to a new station area based on the preset parameters for the next stage and switches the lifting point to the new position.

[0107] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0108] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0109] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0110] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0111] Finally, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for cooperative control of double-machine lifting of a large-span space truss, characterized in that, Comprise: (1) Before hoisting, the whole hoisting process is divided into multiple continuous lifting stages according to the spatial relationship between the net rack and the support, and the corresponding lifting point position, crane station and stage target shape are preset for each stage; (2) In the hoisting process, the hook height, boom elevation angle, load weight and plane position data of the two cranes are obtained in real time; (3) Based on the real-time data, the load weight difference of the double machine is calculated, and the virtual horizontal inclination of the net rack in the direction of the two lifting point connecting line is calculated through the geometric projection relationship of the hook height, boom elevation angle and plane position, so as to construct the synchronous state index; (4) Use the synchronous state index of the current lifting stage to judge the deviation; (5) When there is deviation, select one or combination from the speed fine-tuning instruction based on the load balancing rule and the height compensation instruction based on the posture correction rule to generate adjustment instruction for action adjustment according to the current lifting stage; Compare the real-time calculated load weight difference of the double machine with the preset load balancing allowable limit value of the current lifting stage; Compare the real-time calculated virtual horizontal inclination with the horizontal inclination safety limit value set in the current lifting stage; When either the load weight difference of the double machine or the virtual horizontal inclination exceeds the corresponding limit value, it is judged that there is deviation; Compare the load weights of the current two cranes, and determine the crane with higher load weight as the target adjustment crane; Define the ratio of the current load weight difference to the load balancing allowable limit value of the current lifting stage as the load imbalance degree; According to the load imbalance degree, match the corresponding speed adjustment step from the established speed adjustment step mapping sequence; Based on the matched speed adjustment step, generate a descending speed increase instruction for the target adjustment crane; Determine the speed adjustment interval based on the motor rated parameters of the hoisting control system; Determine the minimum and maximum values of the speed adjustment step length using the speed adjustment interval and the control accuracy requirement; Take the minimum speed adjustment step length as the increment, generate several discrete and step-increasing speed adjustment step lengths between the minimum and maximum speed adjustment step lengths; Through net rack lifting simulation test, the system response under different load imbalance conditions is measured, so as to calibrate the corresponding relationship between load imbalance degree and required speed adjustment, and then establish the experience mapping sequence of the load imbalance degree and the speed adjustment step length; When the deviation is only judged by the load weight difference exceeding the corresponding limit value, the speed fine-tuning instruction based on the load balancing rule is selected; when the deviation is only judged by the virtual horizontal inclination residual exceeding the corresponding limit value, the height compensation instruction based on the attitude correction rule is selected; when the deviation is simultaneously judged by the load weight difference and the virtual horizontal inclination exceeding the corresponding limit value, if the current lifting stage is in the off-ground lifting stage or the crossing support structure stage, the speed fine-tuning instruction based on the load balancing rule is preferentially selected, and after the load weight difference falls within the allowable limit value, the attitude state is re-evaluated, and when the virtual horizontal inclination still exceeds the corresponding limit value, the height compensation instruction based on the attitude correction rule is additionally added; if the current lifting stage is in the high-position translation and attitude adjustment stage or the support precise positioning stage, the height compensation instruction based on the attitude correction rule is preferentially selected, and after the virtual horizontal inclination is stabilized within the allowable limit value, the load weight difference is subsequently monitored, and when the load weight difference still exceeds the corresponding limit value, the speed fine-tuning instruction based on the load balancing rule is additionally added.

2. The cooperative control method for double-machine lifting of a large-span net rack according to claim 1, characterized in that: The division into multiple continuous lifting stages includes: In the lifting path of the grid from the ground assembly state to the final installation and positioning state, the key nodes of the contact or disengagement of the grid structure with the concrete support and the steel column support are the working condition division points; Taking the spatial positions corresponding to these division points as the reference, the continuous lifting path is divided into several ordered and connected lifting stages.

3. The cooperative control method for double-machine lifting of a large-span net rack according to claim 1, characterized in that: The real-time acquisition of the hook height, boom elevation angle, load weight and plane position data of the two cranes is as follows: An absolute value encoder is installed at the hook pulley block of each crane to measure the hook height in real time; A dynamic inclination angle sensor is installed at the root pin of the boom of each crane to measure the boom elevation angle in real time; A side pressure type tension sensor is installed at the fixed end of the lifting steel wire rope of each crane to measure the load weight in real time; A differential GPS positioning device is installed at the center of the slewing platform of each crane to obtain the plane position of the crane in real time.

4. The cooperative control method for double-machine lifting of a large-span net rack according to claim 1, characterized in that: The virtual horizontal inclination is obtained by the following process: A three-dimensional engineering measurement coordinate system is established at the construction site, and the initial coordinates of the two crane rotation centers are determined by total station calibration in the coordinate system; The initial coordinates of the two crane rotation centers are combined with the boom elevation angle and rotation azimuth obtained by the inclination sensor installed on the crane, and the hook height data is fused, and the inverse calculation of the hook three-dimensional space coordinates in the three-dimensional engineering measurement coordinate system is performed by using the boom geometric length and the kinematics forward solution model; Based on the hook space coordinates and the sling length, the actual space positions of the slings and the lifting points are determined, and the space mapping relationship from the hook to the lifting points under the assumption of rigid connection is established; The three-dimensional coordinates of the two lifting points are obtained under the space mapping relationship, and the two-lifting-point connection vector is constructed, and then the projection vector of the two-lifting-point connection vector in the horizontal plane is calculated; The virtual horizontal inclination of the grid along the lifting point connection direction is calculated by the inverse tangent function using the length of the projection vector and the elevation difference of the two lifting points.

5. The cooperative control method for double-machine lifting of a large-span net rack according to claim 1, characterized in that: The height compensation instruction based on the attitude correction rule includes the following contents: The structure inclination direction is determined according to the state of the grid virtual horizontal inclination relative to the horizontal inclination safety limit value, and then the target hook that needs to be lifted or lowered is determined. Based on the inclination residual between the virtual horizontal inclination and the horizontal inclination safety limit value, combined with the projection distance of the two lifting points in the horizontal plane, the height compensation required to eliminate the residual is calculated using the linearized triangle relationship under small angle approximation; The height compensation is decomposed into the relative displacement of the two hooks, which are opposite in direction, and the distribution ratio is set according to the inverse ratio of the current double-machine measured load weight; The displacement direction and the displacement amount after distribution are combined to generate a double-machine height compensation instruction containing the displacement direction and the displacement amount.

6. The cooperative control method for double-machine lifting of a large-span net rack according to claim 1, characterized in that: It also includes (6) when switching from the current lifting stage to the next lifting stage, performing stage switching, which is implemented as follows: Detect whether the net rack shape parameter of the current lifting stage has reached its target shape; When the target shape is reached, send a stage switching instruction to the control system; The control system guides the crane to move to a new station area according to the preset parameters of the next stage, and switches the lifting point to a new position.

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