Tower crane anti-swing control method based on movement compensation technology

Abstract

The invention discloses a tower crane anti-swing control method based on a movement compensation technology. The tower crane anti-swing control method comprises the following steps: step 1, acquiring swing angle data of a crane hook and length data of a steel wire rope and transmitting the data to a data processing module in real time; 2, the data processing module monitors the swing angle of the crane hook, and when the swing angle exceeds a set swing angle threshold value and the time from sending of the last compensation displacement instruction exceeds a time interval threshold value, compensation is triggered; 3, the data processing module calculates compensation displacement and time corresponding to the compensation displacement according to the swing angle data and the length of the steel wire rope, converts the compensation displacement and the compensation time into a compensation displacement instruction, and sends the compensation displacement instruction to the frequency converter; and step 4, the frequency converter drives the variable-amplitude trolley to perform compensation at the operation frequency corresponding to the compensation displacement instruction.

Description

Technical Field

[0001] The present invention relates to the field of anti-sway control of tower cranes, especially an anti-sway control method for tower cranes based on mobile compensation technology. Background Art

[0002] Tower cranes are widely used in construction. Especially when hoisting heavy objects and performing luffing motions, the stability of their operation is directly related to the safety and efficiency of construction. However, during the luffing process of tower cranes, the hook often swings and sways, affecting the hoisting accuracy and even threatening the safety of construction workers in severe cases. Traditional anti-sway control methods can alleviate the sway problem to a certain extent, but for complex dynamic working conditions and non-linear problems, their control effects are limited. With the development of sensor technology and control algorithms, modern anti-sway control methods have gradually adopted more advanced technologies, such as motion compensation based on real-time sensor data, fuzzy control, intelligent control algorithms, etc.

[0003] Most of the existing anti-sway technologies focus on reducing sway by changing the motion trajectory of the luffing trolley. However, these methods often cannot accurately compensate according to the real-time state, so they lack sufficient flexibility and accuracy. To effectively control the sway of tower cranes, researchers have gradually proposed a compensation method based on real-time data feedback, that is, by real-time monitoring the swing angle of the tower crane hook and the length of the wire rope, calculating the compensation displacement, and controlling the motion trajectory of the luffing trolley through a frequency converter, so as to achieve precise anti-sway control. Summary of the Invention

[0004] To solve the above technical problems, the present invention discloses an anti-sway control method for tower cranes based on mobile compensation technology, including the following steps:

[0005] Step 1: Use an IMU (Inertial Measurement Unit) inertial measurement unit to obtain the swing angle data of the crane hook and the wire rope length data of the crane hook measured by a height encoder and transmit them to the data processing module in real time;

[0006] Step 2: The data processing module monitors the swing angle of the crane hook. When the swing angle exceeds the set swing angle threshold and the time since the last compensation displacement command was sent exceeds the time interval threshold, compensation is triggered;

[0007] Step 3: Calculate the compensation displacement, the time and direction corresponding to the compensation displacement through the swing angle data and the wire rope length, convert the compensation displacement, compensation time and compensation displacement direction into a compensation displacement command, and send the compensation displacement command to the frequency converter;

[0008] Step 4: The frequency converter drives the luffing trolley for compensation at the rate corresponding to the compensation displacement command, ensuring that the luffing trolley stops moving at the end of the compensation time and reaches the accurate position.

[0009] In Step 2, the time interval threshold is one-fourth of the swing period of the hook.

[0010] The tower crane includes a boom, a luffing trolley, and a hook. The luffing trolley is slidably connected to the boom and is connected to the hook through a wire rope.

[0011] The specific calculation method of the compensation displacement described in Step 2 is as follows:

[0012] The calculation formula for the compensation displacement d is as follows:

[0013] d = lsin(θ)

[0014] Where l is the length of the wire rope, and θ is the maximum swing angle deviation of the hook within the swing period of the hook corresponding to the starting point of the time when this compensation is triggered.

[0015] The compensation time t required to complete the compensation displacement d = T / 4, where T is the swing period of the hook, and the calculation formula is as follows:

[0016]

[0017] In the formula, l is the length of the wire rope, and g is the acceleration due to gravity.

[0018] In Step 3, if the luffing trolley has an expected moving direction, the compensation displacement direction is equal to the expected moving direction of the luffing trolley; if the luffing trolley has no expected moving direction, then the compensation displacement direction is the same as the swinging direction of the hook when the compensation displacement command is sent.

[0019] The specific method for obtaining the specific time point when the compensation displacement command is sent in Step 3 is as follows:

[0020] The swinging direction of the hook is parallel to the boom. The swinging direction of the hook away from the crane body is defined as the positive direction, and the swinging direction of the hook close to the crane body is defined as the negative direction;

[0021] When the hook is on the side close to the crane body, the reading of the sensor is negative, and when the hook is on the side away from the crane body, the reading of the sensor is positive;

[0022] If the expected moving direction of the luffing trolley is the positive direction, the specific time point when the compensation displacement command is sent is the time point when the reading of the sensor first changes from negative to 0 starting from the time when this compensation is triggered;

[0023] If the expected moving direction of the luffing trolley is the negative direction, the specific time point when the compensation displacement command is sent is the time when the sensor reading changes from a positive value to 0 for the first time, starting from the time when the compensation is triggered.

[0024] If the luffing trolley does not move in the expected direction, the specific time point when the compensation displacement instruction is sent is the time point when the sensor reading changes from a non-zero value to 0 for the first time, starting from the time when the compensation is triggered.

[0025] The compensation displacement instruction described in step 3 includes the inverter operating frequency information, and the frequency f is calculated as follows:

[0026]

[0027] Where d is the compensation displacement, f max is the maximum operating frequency of the inverter, d max It is to set the maximum compensation displacement.

[0028] In step 1, the swing angle data is filtered and denoised, and the filtering methods include Kalman filtering and low-pass filtering.

[0029] In the present invention, preferably, in step 1, the height encoder is a lifting height encoder provided by the tower crane.

[0030] In the present invention, preferably, in step 3, the instruction sending method is PLC (programmable logic controller) communication, using Modbus RTU or CAN bus protocol.

[0031] In the present invention, preferably, in step 1, the IMU inertial measurement unit is used as an angle sensor.

[0032] Beneficial effects:

[0033] The present invention realizes high-precision compensation control through real-time monitoring and calculation. Compared with the traditional control method, the present invention has the following advantages:

[0034] 1. High-precision compensation: Through accurate sensor data acquisition and compensation calculation, the stability of the tower crane's hook during operation is ensured and the swing amplitude is reduced.

[0035] 2. Strong adaptability: The system can dynamically adjust the control strategy according to the real-time swing angle and load changes, and has strong adaptability.

[0036] 3. Improved safety: By setting a safety threshold, the hook can be effectively prevented from colliding with surrounding obstacles or workers, thereby improving construction safety.

[0037] 4. Engineering applicability: The system can be flexibly deployed in actual projects, transmit data through Modbus RTU or CAN bus protocols, be compatible with existing tower crane control systems, achieve simple and efficient integration, be easy to implement in engineering, have an intuitive formula form, and can be quickly mastered and applied by engineering personnel, shortening the debugging cycle.

[0038] 5. High calculation efficiency and strong real-time performance: Low calculation complexity, reducing the calculation burden of the device, suitable for real-time control, capable of quickly calculating compensation displacement instructions, ensuring that the compensation action is synchronized with the hook swing, and still being able to operate stably in a low-computation-resource environment (such as PLC), without being limited by computing power.

[0039] 6. Strong adaptability, easy to integrate and transplant: Can be directly integrated into existing PLCs or other control programs without the need for additional software libraries or mathematical solving tools. Applicable to multiple communication protocols (such as Modbus, CAN), facilitating integration with variable frequency drives, sensors, and control systems of different brands. Applicable to different lifting working conditions and can be extended to other lifting equipment such as bridge cranes and gantry cranes.

[0040] 7. Cost reduction and system reliability improvement: Due to low calculation complexity, low-cost control hardware (such as low-end PLCs) can be used, reducing the overall system cost. The calculation process is concise, reducing the risk of software vulnerabilities or calculation errors, and improving the reliability and maintainability of the system. Description of the Drawings

[0041] Figure 1 It is a schematic diagram of the overall process of the present invention.

[0042] Figure 2 It is a schematic diagram of the moving compensation device for the crane hook.

[0043] Figure 3 It is a schematic diagram of the closed-loop control strategy of the present invention. Detailed Implementation Manner

[0044] The present invention combines multiple technologies such as wire rope length measurement, real-time angle detection, compensation displacement calculation, and closed-loop control system, and proposes an innovative anti-sway control method for tower cranes. By using high-precision encoders and IMU inertial measurement units to obtain the swing angle and wire rope length information of the hook, calculating the compensation displacement and adjusting the compensation action of the tower crane's luffing trolley in real time, it ensures that the swing amplitude of the tower crane during operation is controlled within a safe range, significantly improving the operation safety and construction efficiency of the tower crane.

[0045] Specifically, the present invention applies sensor technology, intelligent control algorithms, and real-time calculation models. By obtaining real-time swing angles, wire rope lengths, and luffing trolley movement information, it realizes precise position and swing control of the tower crane hook, thereby improving construction safety and efficiency, especially preventing the hook from swaying and oscillating during the luffing movement of the tower crane.

[0046] The present invention proposes a computationally efficient and highly engineering-feasible anti-sway compensation method for tower cranes. This method can achieve real-time compensation control without the need for additional high-performance computing hardware, is applicable to different types of tower crane systems, and can be integrated into the existing crane control system through software upgrades, thereby reducing implementation costs, improving construction efficiency, and enhancing the safety and stability of the crane.

[0047] In the actual operation process of a crane, the suspended object of the hook may be blown by strong winds or hit by other objects on the construction site during the lifting process, resulting in swaying. In addition, due to improper or unskilled operation of the tower crane driver (sudden acceleration, emergency braking), swaying may also occur. This accidental swaying is time-consuming and laborious when stabilizing the hook, reduces work efficiency, and is difficult to balance manually. The present invention discloses an anti-sway control method for tower cranes based on mobile compensation technology, which can automatically calm down the swaying of the hook.

[0048] Embodiment:

[0049] Figure 2 In the figure, 1. is the luffing trolley, 2. is the wire rope, 3. is the hook, and 4. is the angle sensor.

[0050] Taking one-time displacement compensation as an example, it includes the following steps:

[0051] Step 1: The angle sensor (model WT9011DCL - BT50) is fixed on the side of the tower crane hook to obtain the swing angle data of the crane hook in real time, and filter and denoise the data. Filtering and denoising the data means using the limit filtering method to remove outliers or noise interference from the measured angle values, aiming to improve the quality of the data and the accuracy of subsequent analysis. The swing angle data and the wire rope length data of the crane hook measured by the height encoder are transmitted to the data processing module in real time;

[0052] Step 2: The data processing module monitors the swing angle of the crane hook. When the swing angle exceeds the set swing angle threshold and the time since the last compensation displacement command was sent exceeds the time interval threshold, compensation is triggered;

[0053] The swing angle threshold is set such that the change in the hook swing angle exceeds the set threshold of 2.5°.

[0054] Step 3: The data processing module calculates the compensation displacement and the corresponding time of the compensation displacement based on the swing angle data and the wire rope length, converts the compensation displacement, compensation time, and compensation displacement direction into a compensation displacement command, and sends the compensation displacement command to the frequency converter;

[0055] According to the angle sensor and the height encoder: the wire rope length l = 30m;

[0056] The time to trigger compensation is the maximum swing angle by which the hook deviates within the swing period of the hook corresponding to the starting point; θ = 8°;

[0057] The calculation formula for the compensation displacement d is as follows:

[0058] d = lsin(θ) = 30×sin(8°) = 4.18m

[0059] The compensation time t required to complete the compensation displacement d = T / 4, where T is the swing period of the hook, and the calculation formula is as follows:

[0060]

[0061] The compensation displacement command includes the frequency converter operating frequency information, and the frequency f is calculated as follows:

[0062]

[0063] In the formula, d is the compensation displacement, f max = 50Hz is the set maximum operating frequency of the frequency converter, d max = 8m is the set maximum compensation displacement. The maximum compensation displacement is related to the maximum speed of the trolley. The maximum speed that the trolley can reach limits the upper limit of the trolley's compensation displacement;

[0064] In this embodiment, the target of the crane is to transport the goods forward along the boom. Then the expected moving direction of the trolley is the positive direction; the sending time of the compensation displacement command is the time when the first swing is in the positive direction and passes through the lowest point within the swing period of the hook corresponding to this time of triggering compensation; record the compensation displacement direction as the positive direction in the compensation command.

[0065] Step 4: The frequency converter drives the trolley for compensation at the rate and direction corresponding to the compensation displacement command, ensuring that the trolley stops moving and reaches the accurate position at the end of the compensation time.

[0066] If the angle is less than the set safety threshold after this round of compensation, the expected goal is achieved. If the angle is still greater than the safety threshold after this round of compensation, then when the interval time exceeds the current time interval threshold (10.99s), the next round of displacement compensation will be triggered. The present invention can ultimately achieve the expected anti-sway effect.

[0067] In step 3, the instruction sending method is to send the calculated compensation displacement instruction to the frequency converter through the Modbus RTU or CAN bus protocol, so as to control the luffing motor to drive the trolley for precise compensation, thereby realizing anti-sway control.

[0068] The Modbus RTU or CAN bus protocol is used to transmit data to the frequency converter through industrial communication standards, ensuring the efficient and accurate transmission of the compensation displacement instruction. The frequency converter adjusts the operating frequency according to the received compensation instruction, so as to precisely control the luffing motor to drive the trolley for compensation movement. Through this process, the luffing trolley of the tower crane can quickly respond to the compensation instruction, realize the precise positioning of the hook and effectively suppress the swing. Through the real-time monitoring and feedback mechanism, the system can continuously adjust and optimize the compensation behavior according to the actual working conditions of the tower crane, thereby ensuring the stability and safety of the tower crane during operation.

[0069] The method disclosed in the present invention is a closed-loop control method. As Figure 3 shown, taking the swing angle as the input, the actual swing angle of the compensation displacement is reduced, and the reduced swing angle continues to be the detection target of the sensor, thus forming a feedback path to form a closed loop until the angle is adjusted to meet the expected value set by us.

[0070] The closed-loop control strategy of the present invention is mainly angle control. The angle control calculates the required compensation displacement by real-time monitoring the gap between the hook swing angle and the set threshold, and adjusts the position of the luffing trolley to ensure the stability of the hook.

[0071] The present invention provides a method for anti-sway control of a tower crane based on mobile compensation technology. There are many methods and ways to specifically implement this technical solution. The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be realized by existing technologies.

Claims

1. A tower crane anti-sway control method based on motion compensation technology, characterized in that: The following steps are involved: Step 1, obtaining the swing angle data of the crane hook and the wire rope length data of the crane hook; Step 2, monitoring the swing angle of the crane hook, triggering compensation when the swing angle exceeds a set swing angle threshold and the time from the last compensation displacement instruction being sent exceeds a time interval threshold; Step 3, calculating the compensation displacement and the time and direction corresponding to the compensation displacement through the swing angle data and the wire rope length, converting the compensation displacement, compensation time and compensation displacement direction into a compensation displacement instruction, and sending the compensation displacement instruction to the frequency converter; Step 4: The frequency converter drives the variable amplitude trolley to perform compensation according to the compensation displacement instruction.

2. The tower crane anti-sway control method based on the motion compensation technology according to claim 1 is characterized in that: In step 2, the time interval threshold is one quarter of the swing period of the hook.

3. The tower crane anti-sway control method based on the motion compensation technology according to claim 1 is characterized in that: The specific calculation method of the compensation displacement described in step 2 is as follows: The calculation formula of compensation displacement d is as follows: d = lsin(θ) Where l is the length of the wire rope, θ is the maximum swing angle of the hook deviation during the swing period of the hook corresponding to the time when the compensation is triggered; The compensation time t=T / 4 required to complete the compensation displacement d, T is the swing period of the hook, and the calculation formula is as follows: Where l is the length of the wire rope and g is the acceleration due to gravity.

4. The tower crane anti-sway control method based on the motion compensation technology according to claim 1 is characterized in that: In step 3, if the luffing trolley has an expected moving direction, the compensation displacement direction is equal to the expected moving direction of the luffing trolley; if the luffing trolley has no expected moving direction, the compensation displacement direction is consistent with the swing direction of the hook when the compensation displacement instruction is sent.

5. The anti-sway control method for a tower crane based on movement compensation technology according to claim 1 is characterized in that: The specific time point at which the compensation displacement instruction is sent in step 3 is obtained in the following manner: The swing direction of the hook is parallel to the boom, and the swing direction of the hook away from the crane body is defined as the positive direction, and the swing direction close to the crane body is defined as the negative direction; When the hook is close to the crane body, the sensor reading is negative, and when the hook is away from the crane body, the sensor reading is positive; If the expected moving direction of the luffing trolley is the positive direction, the specific time point when the compensation displacement instruction is sent is the time when the sensor reading changes from a negative value to 0 for the first time, starting from the time when the compensation is triggered. If the expected moving direction of the luffing trolley is the negative direction, the specific time point when the compensation displacement command is sent is the time when the sensor reading changes from a positive value to 0 for the first time, starting from the time when the compensation is triggered. If the luffing trolley does not move in the expected direction, the specific time point when the compensation displacement instruction is sent is the time point when the sensor reading changes from a non-zero value to 0 for the first time, starting from the time when the compensation is triggered.

6. The tower crane anti-sway control method based on the motion compensation technology according to claim 1 is characterized in that: The tower crane comprises a boom, a luffing trolley and a hook. The luffing trolley is slidably connected to the boom and is connected to the hook via a steel wire rope.

7. The tower crane anti-sway control method based on the motion compensation technology according to claim 1 is characterized in that: The compensation displacement instruction described in step 3 includes the inverter operating frequency information, and the frequency f is calculated as follows: Where d is the compensation displacement, f max is the maximum operating frequency of the inverter, d max It is to set the maximum compensation displacement.

8. The anti-sway control method for a tower crane based on the motion compensation technology according to claim 6 is characterized in that: In step 1, the swing angle data is filtered and denoised, and the filtering method includes Kalman filtering and low-pass filtering.

9. The anti-sway control method for a tower crane based on the motion compensation technology according to claim 1 is characterized in that: In step 3, the instruction sending method is PLC communication, using Modbus RTU or CAN bus protocol.

10. The tower crane anti-sway control method based on the motion compensation technology according to claim 1, characterized in that: In step 1, the swing angle data is measured by an IMU inertial measurement unit, and the height encoder is a lifting height encoder provided by the tower crane.

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