A sway-prevention flexible control method and system applied to a bridge crane

Abstract

This invention belongs to the field of crane control technology, specifically relating to an anti-sway flexible control method and system for bridge cranes. The method includes: acquiring real-time data of the bridge crane during operation; calculating the rope elasticity index at the current moment; determining the position weight using the absolute displacement of the trolley relative to the left end of the main beam and the span of the main beam; calculating the main beam flexibility factor by combining the vibration acceleration of the main beam and the acceleration of the trolley; weighted fusion of the rope elasticity index and the main beam flexibility factor to obtain a stiffness correction coefficient; and completing the correction of the acceleration command to obtain the execution value of the acceleration command, thus achieving flexible control. This invention, by analyzing the flexible characteristics and dynamically adjusting the control gain, suppresses the coupling interference of vertical flexible deformation on horizontal motion, achieving flexible and precise control of the crane.

Description

Technical Field

[0001] This invention relates to the field of crane control technology. More specifically, this invention relates to an anti-sway flexible control method and system for bridge cranes. Background Technology

[0002] In the field of modern high-end equipment manufacturing, lightweight bridge cranes have become an industry trend in response to the needs of energy conservation, emission reduction and green manufacturing. Their main beam structure uses a large amount of high-strength steel for significant weight reduction design. However, the relative reduction in the moment of inertia of the main beam section leads to a decrease in its static and dynamic stiffness in the vertical direction. During load operation, especially during the rapid acceleration and deceleration of the trolley, the main beam exhibits obvious dynamic characteristics of a flexible beam. Furthermore, when the crane is lifting heavy tonnage goods, the wire rope, as a flexible connector, is not an ideal rigid body in the physical sense. Especially under the condition of large lifting height, the axial tension and rebound of the wire rope will form a low-frequency elastic oscillation. This coexistence of the vertical bending vibration of the main beam and the axial extension and contraction oscillation of the rope constitutes a complex flexible mechanical environment.

[0003] To address the load swaying problem, the current traditional anti-sway control method is an idealized rigid pendulum model. This model simplifies the complex hoisting system into a single pendulum, assuming that the steel wire rope connecting the trolley and the load is a massless, non-extensible rigid rod, and that the mechanical structure is a stationary rigid reference frame.

[0004] In actual operation, when the trolley brakes at the mid-span of the main beam, the inertial force not only causes the load to surge forward but also induces the main beam to bounce vertically. Combined with the axial extension and contraction of the rope, this alters the instantaneous stress state of the load. This composite vibration, through the Coriolis effect, converts vertical energy into nonlinear disturbances in the horizontal direction, causing the hook to sway irregularly. Traditional anti-sway control algorithms cannot detect this flexible coupling interference from the vertical dimension. The calculated suppression torque has a significant phase difference with the actual load motion, which includes flexible hysteresis. This can easily lead to the controller applying force at the wrong time, causing over-anti-swaying, resulting in increased oscillation or direct anti-sway failure, seriously affecting positioning accuracy and operational safety. Summary of the Invention

[0005] To address the technical problem of reduced anti-sway control accuracy of traditional rigid models due to flexible deformation of the main beam and ropes in lightweight cranes, this invention provides solutions in the following aspects.

[0006] In a first aspect, the present invention provides an anti-sway flexible control method for bridge cranes, comprising: acquiring real-time rope tension, rope lowering length, main beam vibration acceleration, and trolley acceleration during bridge crane operation; using the ratio of the current rope lowering length to the maximum lowering length of the crane as a swing length flexibility factor; determining a tension fluctuation factor based on the changes in the tension of all ropes within the current time window; using the product of the swing length flexibility factor and the tension fluctuation factor as a rope elasticity index; acquiring the total span of the main beam and the absolute displacement of the trolley relative to the left end of the main beam at the current moment; determining a position weight using the displacement and the total span of the main beam; determining a main beam flexibility factor based on the current main beam vibration acceleration, trolley acceleration, and position weight; weightedly fusing the rope elasticity index and the main beam flexibility factor to determine a stiffness correction coefficient; acquiring the current acceleration command and the compensation acceleration of the anti-sway controller; determining the execution value of the acceleration command using the acceleration command, the compensation acceleration, and the stiffness correction coefficient; and sending the execution value to a frequency converter to achieve flexible control.

[0007] This invention calculates the rope elasticity index, which reflects tensile oscillation, and the main beam flexibility factor, which reflects structural resonance, and then integrates them to generate a stiffness correction coefficient to dynamically correct acceleration commands. It can analyze the dynamic characteristics of soft structures in real time, automatically enhance damping compensation when the system stiffness decreases, effectively suppress the nonlinear coupling interference of vertical flexible deformation on horizontal load motion, solve the phase difference problem between the control model and the actual working conditions, and significantly improve the anti-sway accuracy and operational safety of cranes.

[0008] Preferably, determining the tension fluctuation factor based on the changes in the tension of all ropes within the current time window includes: calculating the standard deviation of the tension of all ropes within the current time window, and dividing the standard deviation by the rated value of the crane rope tension to obtain the tension fluctuation factor.

[0009] This invention captures low-frequency elastic oscillation characteristics by analyzing the flexibility of the rope and the changes in rope tension over a short period of time, thus preventing anti-sway failure caused by ignoring nonlinear interference in long rope conditions.

[0010] Preferably, the absolute displacement of the trolley relative to the left end of the main beam at the current moment is obtained by: determining the origin by using a zero-position calibration switch installed at the left end of the main beam, and using the encoder of the trolley's walking motor to collect the pulse increment of the trolley's movement in real time. The pulse increment is then multiplied by the pulse equivalent obtained through the current encoder parameters to obtain the absolute displacement of the trolley relative to the left end of the main beam.

[0011] Preferably, the position weights satisfy the expression: In the formula, The position weight at the current moment; This represents the absolute displacement of the trolley relative to the left end of the main beam at the current moment. The total span of the main beam.

[0012] This invention utilizes parabolic functions to fit the vibration mode of a simply supported beam to calculate position weights, mapping the stiffness-sensitive area of ​​the trolley on the main beam, and achieving precise regional control: the maximum suppression weight is applied in the mid-span flexible high-incidence area, and intervention is reduced in the end rigid area, avoiding unnecessary anti-sway overcompensation.

[0013] Preferably, the main beam flexibility factor satisfies the following expression: In the formula, The current moment represents the main beam flexibility factor; The position weight at the current moment; This represents the vibration acceleration of the main beam at the current moment. It is the acceleration due to gravity; The acceleration of the car at the current moment; This is the limit value for the accelerometer of the trolley under normal operating conditions; The sign for absolute value.

[0014] This invention introduces an acceleration term, along with position weights and vibration acceleration, to construct a flexibility factor. By analyzing the abrupt change rate of acceleration, it identifies structural resonances caused by violent movements of the vehicle. This not only filters out static deformation interference during steady-state acceleration but also integrates the energy coupling strength between the vehicle and the beam, ensuring that anti-sway compensation intervenes at the moment of actual structural resonance.

[0015] Preferably, the jerk of the vehicle is equal to the ratio of the first-order difference of the vehicle's acceleration at the current moment to the sampling interval.

[0016] Preferably, determining the stiffness correction coefficient includes: taking the product of the rope elasticity index and a preset first weight as a first term, taking the product of the main beam flexibility factor and a preset second weight as a second term, and summing the foundation gain value 1 with the first term and the second term to obtain the stiffness correction coefficient.

[0017] This invention constructs a dynamically amplified stiffness corrector, realizing adaptive adjustment of control parameters: when the flexible disturbance increases, the correction coefficient automatically increases, and a stronger damping torque is output to ensure the load returns to stability.

[0018] Preferably, determining the execution value of the acceleration command includes: calculating the product of the stiffness correction coefficient and the compensation acceleration, and subtracting the product from the acceleration command of the operation to obtain the execution value of the acceleration command.

[0019] Preferably, the implementation of flexible control includes: the frequency converter controlling the trolley to generate corresponding movements according to the received execution value, thereby realizing the flexible control of the bridge crane.

[0020] Secondly, the present invention provides an anti-sway flexible control system for bridge cranes, comprising a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the aforementioned anti-sway flexible control method for bridge cranes is implemented.

[0021] By adopting the above technical solution, a computer program for the anti-sway flexible control method applied to bridge cranes is generated and stored in a memory for loading and execution by a processor. Terminal equipment is then created based on the memory and processor for convenient use.

[0022] The beneficial effects of this invention are as follows:

[0023] The core of this invention lies in solving the anti-sway problem caused by the dual flexible coupling of the crane structure and ropes. By constructing the rope elasticity index and the main beam flexibility factor, vertical deflection and axial extension are transformed into predictable control gains. Based on the traditional rigid anti-sway model, a stiffness correction coefficient is introduced to achieve adaptive control with the combined action of rigidity and flexibility. This solves the instability caused by control phase lag, while also taking into account operating efficiency, and realizes high-precision positioning of lightweight equipment under complex working conditions. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating an anti-sway flexible control method for bridge cranes according to the present invention;

[0025] Figure 2 This diagram schematically illustrates a comparison of the vibration suppression effects of the present invention and conventional control methods on the main beam. Detailed Implementation

[0026] 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, not all, of the embodiments of the present invention. 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.

[0027] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] This invention discloses an anti-sway flexible control method for bridge cranes, referring to... Figure 1 This includes steps S1-S5:

[0029] S1. Obtain real-time data of the bridge crane during operation.

[0030] It should be noted that in order to achieve real-time perception of the structural-rope flexibility state of lightweight bridge cranes, the micro-vibration of the structure and the change in rope tension are the core basis for judging the strength of flexibility interference. Therefore, it is not possible to rely solely on traditional encoder data. Dynamic sensing sensors must be introduced to collect data synchronously and provide data basis for anti-sway flexibility control analysis.

[0031] Specifically, a MEMS triaxial accelerometer is installed at the mid-span of the main beam to collect the vibration acceleration of the main beam perpendicular to the ground in real time according to a preset sampling frequency; a resistance strain gauge tension sensor is installed below the bearing seat of the hoisting mechanism drum to collect the rope tension in real time according to a preset sampling frequency; the trolley's acceleration is obtained through the encoder feedback interface of the trolley traveling mechanism frequency converter at a preset sampling frequency; the real-time rope lowering length is obtained through the hoisting encoder data interface of the bridge crane at a preset sampling frequency; and the data from all the sensors and encoders are aggregated to the central controller through the crane bus to ensure real-time control can be achieved subsequently.

[0032] In this embodiment, the preset sampling frequency of all sensors and encoders is set to 100Hz to ensure that the real-time collected data is strictly aligned on the time axis. The implementer can adaptively adjust the sampling frequency according to the actual working conditions. The process parameters of this crane model are extracted, including the rated value of the rope tension and the maximum lowering length.

[0033] Thus, the real-time rope tension, rope lowering length, main beam vibration acceleration, and trolley acceleration of the bridge crane during operation were obtained.

[0034] S2. For the current moment: the ratio of the rope lowering length to the maximum lowering length of the crane is used as the pendulum length flexibility factor, and the tension fluctuation factor is determined based on the rope tension within the time window; the rope elasticity index is obtained by combining the pendulum length flexibility factor and the tension fluctuation factor.

[0035] It should be noted that a steel wire rope, when under load, behaves like a spring with a specific stiffness coefficient. Its stiffness is inversely proportional to its length. As the lifting height increases (i.e., the rope length increases), the rope stiffness decreases. In this case, if external disturbances occur, the rope is prone to axial expansion and contraction oscillations. This oscillation manifests as violent fluctuations around the average tension value. However, considering that even with large tension fluctuations in a short rope configuration, the displacement deviation is small due to the high stiffness, while in a long rope configuration, the same tension fluctuation means a huge displacement deviation. Therefore, it is necessary to combine the tension fluctuation with the rope length weight to reflect the degree of interference of elastic potential energy on anti-sway control.

[0036] Specifically, the preset time window size is N. The time window is used to define the statistical time window for calculating tension fluctuations. If the value is too large, it will introduce a large calculation delay, causing the system to fail to capture the sudden onset of rope elastic oscillations in time, resulting in control phase lag. If the value is too small, it will lead to insufficient sample size, and the statistical results will be easily affected by high-frequency electromagnetic noise from the sensor, resulting in false fluctuations and causing control malfunctions. Therefore, the length of the time window ranges from [10, 50]. In this embodiment, it is set to 20, corresponding to 200ms at a 100Hz sampling frequency. In order to effectively filter out high-frequency random noise while retaining the characteristics of low-frequency mechanical oscillations of the rope, so as to ensure that the algorithm has both noise resistance and real-time response capability to elastic oscillations, the implementers make fine adjustments based on the sampling frequency of the field controller and the inherent vibration frequency of the wire rope. For the moments when the complete time window is not obtained, i.e., the first 20 moments, the missing data is filled in by linear interpolation fitting method.

[0037] Extract all rope tensions within the current time window, where the current time is the last moment within the time window.

[0038] The tension fluctuation factor at the current moment is obtained by: calculating the standard deviation of all rope tensions within the time window of the current moment, and dividing the standard deviation by the rated value of the crane rope tension to obtain the tension fluctuation factor at the current moment.

[0039] In this case, since the absolute tension changes greatly when hoisting loads of different weights, the simple difference in tension cannot measure the degree of danger of the system. The rated value of the rope tension is used as a global benchmark for normalization, and the tension fluctuation is converted into a pure physical proportion relative to the system limit. This assesses the depth of disturbance of the longitudinal elastic oscillation on the overall load-bearing capacity of the system in a short period of time. The larger the tension fluctuation factor, the more intense the energy exchange is taking place inside the rope in a short period of time, that is, the rope is undergoing frequent stretching and rebound processes.

[0040] Furthermore, the current rope lowering length and the maximum lowering length of the crane are obtained, and the ratio of the current rope lowering length to the maximum lowering length of the crane is calculated to obtain the pendulum length flexibility factor at the current moment.

[0041] According to the dynamics of a simple pendulum and the theory of equivalent axial stiffness of a rope, the longer the rope, the lower its equivalent axial stiffness, and the more the system tends to be in a soft state. This means that the same tension fluctuation will be transformed into a huge physical displacement deviation in the case of a long rope, while it will only be a small elastic deformation in the case of a short rope. Therefore, the larger the pendulum length flexibility factor, the longer the rope is lowered at the current moment, which means that the spring effect of the rope at the current moment is more significant, and the stronger the nonlinear coupling interference it generates on the horizontal motion of the load is, and the more likely the anti-sway controller is to experience phase lag.

[0042] In the flexible dynamics mechanism of cranes, the actual elastic displacement and oscillation amplitude of the system's terminal load are jointly determined by the internal tensile excitation intensity characterized by the tension fluctuation factor and the spatial structural compliance characterized by the pendulum length flexibility factor. Therefore, multiplying the tension fluctuation factor and the pendulum length flexibility factor at the current moment yields the rope elasticity index at the current moment. When the system is in a deformable long rope state and severe internal tensile rebound occurs, the output rope elasticity index will increase significantly, identifying the composite elastic oscillation threat that actually interferes with anti-sway control.

[0043] At this point, the rope elasticity index at the current moment is obtained.

[0044] S3. Determine the position weight using the absolute displacement of the trolley relative to the left end of the main beam and the span of the main beam, and calculate the flexibility factor of the main beam by combining the vibration acceleration of the main beam and the acceleration of the trolley.

[0045] It should be noted that the lightweight main beam is a flexible beam simply supported at both ends. Its stiffness distribution in the vertical direction is uneven. Generally, the stiffness at both ends is infinite, and the stiffness at the mid-span is the smallest. The same excitation force will cause the largest deformation at the mid-span, while it has almost no effect at both ends. For a simply supported beam structure, the flexible deformation curve of the main beam is approximately parabolic. It is necessary to determine the distance between the trolley and the endpoints of the main beam. By mapping it to the parabolic function, it can be determined whether the trolley is in the softest mid-span region or the relatively stiff end region, so as to avoid unnecessary anti-sway overcompensation when the end stiffness is better.

[0046] Specifically, the total span of the main beam of the crane is obtained from the standard parameters of the current crane; the absolute displacement of the trolley relative to the left end of the main beam at the current moment is obtained by: determining the origin by using the zero-position calibration switch installed at the left end of the main beam, and using the encoder of the trolley travel motor to collect the pulse increment of the trolley travel in real time. The pulse increment is multiplied by the pulse equivalent obtained by the current encoder parameters to obtain the absolute displacement of the trolley relative to the left end of the main beam.

[0047] The position weight at the current moment is determined using the absolute displacement of the trolley relative to the left end of the main beam and the total span of the main beam; the position weight satisfies the expression:

[0048]

[0049] In the formula, The position weight at the current moment; This represents the absolute displacement of the trolley relative to the left end of the main beam at the current moment. The total span of the main beam.

[0050] in, Reflecting the position weight at the current moment, through Parabolic functions are used to fit the first-order vibration mode characteristics of a simply supported beam, through coefficients. Normalize to make the trolley at the mid-span. The value approaches 1, and the car is at both ends. The value approaches 0; The larger the value, the closer the trolley is to the mid-span region of the main beam. At this point, the vertical dynamic stiffness of the main beam is the lowest. The same acceleration and deceleration action will cause the largest flexible deformation, which means that the current position is a high-incidence area of ​​flexible vibration of the main beam. The system is extremely sensitive to vibration, and the anti-sway algorithm needs to be given the largest weight to suppress it. Conversely, the smaller the value, the more it means that the trolley is located at the end, the main beam is rigid, and there is no need for excessive intervention.

[0051] It should be further explained that for the main beam to experience a truly dangerous flexible resonance, three physical conditions must be met simultaneously: the trolley must be in the most vulnerable spatial position of the structure, there must be a high-frequency kinematic excitation source, and the structure must undergo real dynamic deformation. From a physics perspective, the bouncing vibration of the main beam mainly occurs when acceleration changes abruptly, while the trolley is in a state of uniform acceleration, where the acceleration value is large but constant. The main beam will usually maintain a static deformation rather than continuous oscillation. What truly causes the oscillation is the jerk, i.e., the derivative of acceleration. If the trolley's acceleration is used as a factor, it may be misjudged as a high-risk state when the trolley is accelerating in steady state, leading to unnecessary strong damping intervention and affecting control accuracy. Therefore, a main beam flexibility factor is constructed by comprehensively considering the three physical conditions.

[0052] Specifically, the main beam flexibility factor is determined based on the current position weight, the vertical vibration acceleration of the main beam, and the acceleration of the trolley; the main beam flexibility factor satisfies the following expression:

[0053]

[0054] In the formula, The current moment represents the main beam flexibility factor; The position weight at the current moment; This represents the vibration acceleration of the main beam at the current moment. It is the acceleration due to gravity; Let be the jerk of the car at the current moment, which is equal to the ratio of the first difference of the car's acceleration at the current moment to the sampling interval; The jerk limit value for the trolley under normal operation is obtained through process design parameters; The sign for absolute value.

[0055] in, It reflects the energy coupling strength between the excitation source and the response at the current moment. This indicates the intensity of the excitation source output by the trolley control at the current moment. This indicates the intensity of the vibration response from the main beam structure at the current moment. The jerk reflects the rate of change in current acceleration. A larger product of the two indicates that the trolley's violent movements are effectively translating into violent structural vibrations, signifying strong energy transfer and resonance between the trolley and the beam. In this case, without compensation from anti-sway control, such oscillations are easily exacerbated. If the trolley is currently located at a highly rigid end, i.e. When the value approaches 0, regardless of how violent the trolley's movements or vibrations are, the product result will approach 0, indicating that the vibration at this point is mainly caused by high-frequency noise or non-structural factors, and will not lead to large-amplitude flexible swaying. Anti-sway control does not need to intervene. Only when the trolley reaches the mid-span area, i.e. The product only reaches its peak when the value approaches 1 and the energy coupling strength is greater. This indicates that the current structural vibration is not only strong, but is also triggered by improper operation of the vehicle at its most vulnerable position. This means that the system has structural flexible resonance at this time and needs to be controlled.

[0056] At this point, the flexibility factor of the main beam at the current moment has been obtained.

[0057] S4. The rope elasticity index and the main beam flexibility factor are weighted and fused to obtain the stiffness correction coefficient.

[0058] It should be noted that after obtaining the rope elasticity index and the main beam flexibility factor, they need to be converted into adjustment parameters that the control algorithm can recognize. The parameters of traditional anti-sway models are usually fixed for rigid models and cannot adapt to flexible changes. When the rope elasticity index or the main beam flexibility factor is detected to increase, it means that the system has become unstable and unpredictable. At this time, the control strategy should tend to be high-damping and soft-response, and absorb the oscillation energy by increasing the weight of the suppression term in the control output. Therefore, the stiffness correction coefficient is obtained by fusing the two parameters.

[0059] The current rope elasticity index and the main beam flexibility factor are weighted and fused to determine the current stiffness correction coefficient; the stiffness correction coefficient satisfies the expression:

[0060]

[0061] In the formula, This is the stiffness correction factor at the current moment; Basic gain; The first weight is preset; The second weight is preset; The current moment represents the rope's elasticity index; This represents the flexibility factor of the main beam at the current moment.

[0062] in, Reflecting the degree to which the system deviates from the ideal rigid model at the current moment, this expression is constructed based on the energy superposition principle of orthogonal flexible states. The longitudinal elastic expansion and contraction oscillation of the wire rope and the transverse vertical bending resonance of the main beam belong to two mutually orthogonal independent flexible modes in the dynamic space. According to the energy superposition theorem, the total flexible disturbance energy of the system is equal to the linear superposition of the energies of each orthogonal mode. The larger the value, the more intense the elastic expansion and contraction of the rope is at the moment, or the trolley is located at the softest part of the main beam, which has triggered strong structural resonance, or both of these occur at the same time. This means that the current dynamic stiffness of the system is extremely low, and the trajectory of the load contains a large number of high-frequency oscillation components that cannot be predicted by the rigid model. Therefore, a correction coefficient much greater than 1 is output so that the lower the system stiffness, the larger the correction coefficient is, thereby improving the subsequent flexible control effect.

[0063] It should be added that the first weight is used to amplify the influence of the rope elasticity index on the control gain. When the crane is fully loaded and under extreme long-rope conditions, and the rope experiences severe elastic oscillations, the maximum value of the measured standard deviation of the tension typically fluctuates between 1% and 2% of the rated load. Since the rope elasticity index is composed of the product of the pendulum length flexibility factor and the tension fluctuation factor, its theoretical output peak under extreme high-risk conditions converges to... In anti-sway control theory, to effectively absorb this low-frequency oscillation energy without causing over-damping stoppage in the system, a stiffness correction coefficient is needed to provide an additional dynamic compensation margin of 10% to 50%. Substituting the limit boundary values, the following is derived: The effective control boundary is from 0.1 / 0.01=10 to 0.5 / 0.01=50, which is preferred in this invention. To ensure the system can accurately release 30% of the optimal compensation gain under extreme tensile force fluctuations; the second weight is used to adjust the influence weight of the main beam vibration on the control gain. Since the main beam flexibility factor characterizes the energy coupling strength between the excitation source and the response, in extreme emergency stop tests, the trolley acceleration approaches the limit and the maximum vertical vibration acceleration excited at the mid-span position is usually between 0.1 and 0.2. Therefore, the ultimate physical peak value of the main beam flexibility factor falls within the range of 0.1 to 0.2. In order to quickly suppress the high-frequency resonance of the main beam, while ensuring that the trolley still has sufficient speed response capability in the mid-span region, the additional dynamic compensation margin allocated by the system for resonance suppression is strictly limited to between 10% and 40%. Combined with the ultimate physical peak value, the cross boundary is calculated: the lower bound is 0.1 / 0.2=0.5, and the upper bound is 0.4 / 0.2=2. The preferred embodiment of this invention is... This means that when the flexibility factor of the typical strong resonance main beam is 0.2, the system precisely adds 24% of suppression damping, achieving the Pareto optimal configuration of the main beam's vibration suppression effect and spatial operating efficiency. Implementers can fine-tune the first and second weights based on the actual crane application.

[0064] At this point, the stiffness correction coefficient for the current moment is obtained.

[0065] S5. The stiffness correction coefficient is used to correct the compensation acceleration of the anti-sway controller, and the execution value of the acceleration command is obtained by combining the acceleration command, so as to realize flexible control.

[0066] It should be noted that the parameters of traditional anti-sway controllers are based on rigid models, so the calculated damping force is often too small to overcome these additional flexible energy fluctuations. Furthermore, due to the physical hysteresis of flexible deformation, the control phase will lag, resulting in braking instability. Therefore, a stiffness correction coefficient is introduced to dynamically amplify the basic control parameters: when the system is detected to soften, it means that the potential oscillation energy is huge. The system outputs a stronger damping signal to dissipate the excess oscillation energy and force the load to quickly return to a stable state.

[0067] Specifically, it obtains the acceleration command for the current operation and the compensation acceleration of the anti-shake controller.

[0068] It should be added that the acceleration command for the operation is obtained by reading the signal from the crane operating handle; the compensation acceleration is calculated in real time by the basic anti-sway model inside the crane controller to suppress rigid swaying.

[0069] The stiffness correction coefficient at the current moment is used to correct the compensation acceleration, and the execution value of the acceleration command at the current moment is calculated. The execution value of the acceleration command is obtained by calculating the product of the stiffness correction coefficient at the current moment and the compensation acceleration. The execution value of the acceleration command is equal to the acceleration command of the crane operating handle at the current moment minus the product.

[0070] The product reflects the current moment's enhanced anti-sway suppression effect. When the system is in a stable rigid state, it degenerates into standard anti-sway control, ensuring the smoothness of normal operation. When the system is in a high-risk flexible coupling state, the product is significantly amplified. At this time, the execution of acceleration commands will be significantly reduced, and the reverse torque output by the motor will be more intense, effectively compensating for the sway caused by structural flexibility.

[0071] Finally, the execution value is sent to the frequency converter, which adaptively controls the trolley to produce corresponding movements based on the received instructions, thereby realizing the flexible control of the bridge crane.

[0072] For example, Figure 2This diagram compares the vibration suppression effects of the main beam under the present invention and traditional control methods. The horizontal axis represents time, the left vertical axis represents the trolley acceleration, and the right vertical axis represents the main beam vibration acceleration. At 2 seconds, the trolley acceleration curve shows a sharp negative drop, corresponding to the huge inertial impact generated by the brake engaging. Since the load below is not stationary, the horizontal component of its residual swaying causes inertial pull on the trolley, resulting in repeated swaying of the trolley in the hovering position. Traditional anti-sway control is based on rigid control. Due to the fixed and small system damping, the main beam cannot resist the inertial pull interference of the trolley, resulting in the main beam continuing to oscillate significantly after an emergency stop. In contrast, the flexible control logic of the present invention identifies the vibration risk and dynamically increases the stiffness correction coefficient, reducing the vibration elimination time from more than 10 seconds to less than 2 seconds, effectively suppressing the transmission of vibration energy from the traveling mechanism to the main beam structure.

[0073] This invention also discloses an anti-sway flexible control system for bridge cranes, including a processor and a memory. The memory stores computer program instructions, which, when executed by the processor, implement an anti-sway flexible control method for bridge cranes according to the present invention.

[0074] The system also includes other components well known to those skilled in the art, such as communication buses and communication interfaces, the settings and functions of which are known in the art and will not be described in detail here.

Claims

1. A method for anti-sway flexible control applied to bridge cranes, characterized in that, include: The system acquires real-time data on rope tension, rope lowering length, main beam vibration acceleration, and trolley acceleration during the operation of the bridge crane. The ratio of the current rope lowering length to the maximum lowering length of the crane is used as the pendulum length flexibility factor; the tension fluctuation factor is determined based on the changes in the tension of all ropes within the current time window; the product of the pendulum length flexibility factor and the tension fluctuation factor is used as the rope elasticity index. Obtain the total span of the main beam and the absolute displacement of the trolley relative to the left end of the main beam at the current moment; use the displacement and the total span of the main beam to determine the position weight; determine the main beam flexibility factor based on the vibration acceleration of the main beam, the acceleration of the trolley, and the position weight at the current moment. The stiffness correction coefficient is determined by weighting and fusing the rope elasticity index and the main beam flexibility factor. The system acquires the acceleration command for the current operation and the compensation acceleration of the anti-sway controller; it uses the acceleration command, the compensation acceleration, and the stiffness correction coefficient to determine the execution value of the acceleration command; and it sends the execution value to the frequency converter to achieve flexible control.

2. The anti-sway flexible control method for bridge cranes according to claim 1, characterized in that, The determination of the tension fluctuation factor based on the changes in all rope tensions within the current time window includes: Calculate the standard deviation of all rope tensions within the current time window, and divide the standard deviation by the rated value of the crane rope tension to obtain the tension fluctuation factor.

3. The anti-sway flexible control method for bridge cranes according to claim 1, characterized in that, The method for obtaining the absolute displacement of the trolley relative to the left end of the main beam at the current moment is as follows: The origin is determined by a zero-position calibration switch installed at the left end of the main beam, and the pulse increment of the trolley's movement is collected in real time by the encoder of the trolley's walking motor. The pulse increment is multiplied by the pulse equivalent obtained through the current encoder parameters to obtain the absolute displacement of the trolley relative to the left end of the main beam.

4. The anti-sway flexible control method for bridge cranes according to claim 1, characterized in that, The position weights satisfy the expression: ； In the formula, The position weight at the current moment; This represents the absolute displacement of the trolley relative to the left end of the main beam at the current moment. The total span of the main beam.

5. The anti-sway flexible control method for bridge cranes according to claim 1, characterized in that, The main beam flexibility factor satisfies the following expression: ； In the formula, The current moment represents the main beam flexibility factor; The position weight at the current moment; This represents the vibration acceleration of the main beam at the current moment. It is the acceleration due to gravity; The acceleration of the car at the current moment; This is the limit value for the accelerometer of the trolley under normal operating conditions; The sign for absolute value.

6. The anti-sway flexible control method for bridge cranes according to claim 5, characterized in that, The jerk of the vehicle is equal to the ratio of the first-order difference of the vehicle's acceleration at the current moment to the sampling interval.

7. The anti-sway flexible control method for bridge cranes according to claim 1, characterized in that, The determination of the stiffness correction coefficient includes: The product of the rope elasticity index and the preset first weight is taken as the first term, and the product of the main beam flexibility factor and the preset second weight is taken as the second term. The basic gain value 1 is summed with the first term and the second term to obtain the stiffness correction coefficient.

8. The anti-sway flexible control method for bridge cranes according to claim 1, characterized in that, The determination of the execution value of the acceleration command includes: Calculate the product of the stiffness correction coefficient and the compensation acceleration, and subtract the product from the acceleration command of the operation to obtain the execution value of the acceleration command.

9. The anti-sway flexible control method for bridge cranes according to claim 1, characterized in that, The implementation of flexible control includes: The frequency converter controls the trolley to produce corresponding movements based on the received execution value, thereby realizing flexible control of the bridge crane.

10. A flexible anti-sway control system for bridge cranes, characterized in that, include: A processor and a memory, the memory storing computer program instructions that, when executed by the processor, implement an anti-sway flexible control method for a bridge crane according to any one of claims 1-9.

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