Balance control method based on counterweight movement of counter-jib of tower crane

Abstract

A balance control method based on a counterweight movement of a counter-jib of a tower crane, comprising the following steps: S1, acquiring a boom moment and a counter-jib moment of the tower crane; S2, acquiring the position of a counterweight trolley for the counter-jib on the basis of the boom moment and the counter-jib moment, and automatically adjusting the position of the counterweight trolley on the basis of a working state of the tower crane; and S3, determining that, when the difference between the boom moment and the counter-jib moment is greater than a high threshold, a counterweight frequency inverter of the counter-jib drives an alternating current motor to move at a high speed; when the difference between the boom moment and the counter-jib moment is greater than a medium threshold, the counterweight frequency inverter of the counter-jib drives the alternating current motor to move in a medium speed; when the difference between the boom moment and the counter-jib moment is greater than a low threshold and less than the medium threshold, the counterweight frequency inverter of the counter-jib drives the alternating current motor to move at a low speed; and when the difference between the boom moment and the counter-jib moment is less than the low threshold, the tower crane is in a balanced state, and all moving devices remain unchanged.

Description

A balance control method based on the counterweight movement of the tower crane balance arm Technical Field

[0001] The present invention relates to the technical field of tower crane control, in particular to a balance control method based on the counterweight movement of a tower crane balance arm. Background Art

[0002] The jib and counter-jib are two key components of a tower crane, responsible for supporting and balancing the crane body and lifting cargo. The counter-jib's counterweight trolley is a device used to adjust the arm's weight. By moving the trolley to different positions, the center of gravity of the arm is altered, achieving balance adjustment.

[0003] Existing tower crane self-balancing control methods primarily utilize inclination sensors to monitor the tilt and direction of the crane's balance arm, determining which side requires balancing adjustment based on the tilt and direction. Weight sensors monitor the weight of the crane's balance arm and counterweight, as well as the center of gravity between the two, and adjust the counterweight's position based on the center of gravity. Position sensors monitor the position and motion of the counterweight trolley to determine its current position and travel distance, thereby controlling its movement. A controller then reads sensor data and executes a corresponding algorithm to adjust the trolley's displacement, achieving automatic adjustment of the crane's balance arm. However, this method requires a large amount of sensor data, requiring time to collect and process sensor data, resulting in delayed response times. Furthermore, the counterweight trolley's displacement cannot be finely adjusted, reducing the stability and safety of the balance arm. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a balancing control method based on the counterweight movement of a tower crane balancing arm with high accuracy, safety and reliability.

[0005] The technical solution of the present invention is: a balance control method based on the counterweight movement of the tower crane balance arm, comprising the following steps:

[0006] S1: Obtain the lifting arm moment and balance arm moment of the tower crane;

[0007] S2: Obtain the position of the counterweight trolley of the balancing arm according to the lifting arm torque and the counterweight arm torque, and automatically adjust the position of the counterweight trolley according to the working status of the tower crane;

[0008] S3: When the difference between the lifting arm torque and the balance arm torque is greater than the high threshold, the balance arm counterweight inverter drives the AC motor to move at high speed; when the difference between the lifting arm torque and the balance arm torque is greater than the medium threshold, the balance arm counterweight inverter drives the AC motor to move at medium speed; when the difference between the lifting arm torque and the balance arm torque is greater than the low threshold and less than the medium threshold, the balance arm counterweight inverter drives the AC motor to move at low speed; when the difference between the lifting arm torque and the balance arm torque is less than the low threshold, the tower crane is in a balanced state and all moving components remain unchanged.

[0009] Furthermore, the method further includes step S4: the main hook of the tower crane is lifted, the main hook frequency converter drives the main hook AC motor to slowly lift the hook, and steps S1 to S3 are repeated until a new equilibrium state is reached.

[0010] Furthermore, the method further includes step S5: when the main hook lifts the object off the ground, the main hook frequency converter drives the main hook AC motor to lift the hook at a normal speed, and repeats steps S1 to S3 until a new equilibrium state is reached.

[0011] Furthermore, the method further includes step S6: when the main hook hoisted object reaches a safe height, the main hook trolley inverter drives the main hook AC motor to move forward or backward normally, and repeats steps S1 to S3 until a new equilibrium state is reached.

[0012] Furthermore, step S7 is included: during the self-balancing process, when the balancing arm counterweight trolley and the main hook reach the front and rear limits, they are protected by three levels: the displacement sensor limit, the travel switch limit and the mechanical limit, and an alarm is sounded at the same time.

[0013] Furthermore, in step S1, the boom moment M1 is obtained by the following formula: M1=G1*L1; the balance arm moment M2 is obtained by the following formula: M2=G2*L2;

[0014] Where G1 is the gravity of the boom truss, L1 is the distance from the center of gravity of the boom to the center of the tower; G2 is the gravity of the balance arm truss, L2 is the distance from the center of gravity of the balance arm to the center of the tower.

[0015] Furthermore, in S2, according to the boom moment M1 and the balance arm moment M2, we obtain: M1+G3*L3=M2+G4*L4;

[0016] In the formula, G3 is the gravity of the hoisted object, L3 is the distance from the center of gravity of the hoisted object to the center of the tower body; G4 is the gravity of the counterweight trolley, L4 is the distance from the center of gravity of the counterweight trolley to the center of the tower body; the position of the counterweight trolley is calculated by dynamically calculating the sum of the hoisted object torque and the crane arm torque, and the difference between the sum and the balance arm torque, and then based on the gravity of the counterweight trolley.

[0017] Further, in S3, the high threshold is 200 kN.m or less than -200 kN.m; the middle threshold is 75 kN.m or less than -75 kN.m; and the low threshold is 50 kN.m or less than -50 kN.m.

[0018] Furthermore, in S3, the AC motor has a high-speed motion range of 28-32 Hz, a medium-speed motion range of 23-27 Hz, and a low-speed motion range of 18-22 Hz.

[0019] Furthermore, L1 and L2 are used to calculate the center of gravity position through the displacement data measured by the displacement sensors on the crane arm and the balance arm respectively; the gravity of the hoisted object is obtained through the value of the crane side tension sensor; and the distance L3 from the center of gravity of the hoisted object to the center of the tower body is calculated based on the value of the crane side tension sensor and the displacement of the displacement sensor center.

[0020] The beneficial effects of the present invention are as follows: on the one hand, the position of the counterweight trolley is obtained by the lifting arm torque and the balancing arm torque, and the balance arm counterweight inverter is controlled to drive the AC motor to move at a corresponding speed according to the comparison between the difference between the lifting arm torque and the balancing arm torque and different thresholds, so that the counterweight trolley can be automatically adjusted, which greatly improves the response speed, stability and adjustment accuracy, and has the advantages of good visibility, simple operation, simple algorithm, high intelligence, convenient maintenance, strong adaptability, etc., and can adapt to various working conditions to ensure the safe operation of the tower crane; on the other hand, the position of the counterweight trolley is automatically adjusted during the process of main hook lifting, lifting objects off the ground, and lifting objects to a safe height to ensure the safety and stability of the tower crane; furthermore, by setting three protections during the self-balancing process, the accuracy, safety and reliability of the counterweight trolley and the main hook trolley reaching the extreme positions can be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic structural diagram of a tower crane according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] A balance control method based on the counterweight movement of a tower crane balance arm comprises the following steps:

[0024] S101: Obtain the lifting arm torque and the balance arm torque of the tower crane.

[0025] Specifically, the tower crane includes a boom 1 and a balance arm 2, each of which is provided on either side of the tower body. A counterweight is provided on the balance arm 2, and a counterweight is mounted on the balance arm. Since the counterweight is a movable structure, the counterweight and the movable structure are collectively referred to as a counterweight trolley 3. The counterweight trolley 3 can move along the balance arm 2 to adjust the offset of the center of gravity during the lifting process of the boom. Displacement sensors are provided on both the boom 1 and the balance arm 2 for detecting their respective movement data. A tension sensor is provided at the location where the boom is hoisted to weigh the hoisted object.

[0026] The boom moment M1 is obtained by the following formula: M1 = G1 * L1;

[0027] The balance arm moment M2 is obtained by the following formula: M2 = G2*L2.

[0028] Where G1 is the weight of the boom truss, L1 is the distance from the center of gravity of the boom to the center of the tower, G2 is the weight of the balance arm truss, and L2 is the distance from the center of gravity of the balance arm to the center of the tower.

[0029] Among them, G1 and G2 are known constants, L1 and L2 can be used to measure the displacement of the crane arm and the balance arm respectively through the displacement sensors on the crane arm and the balance arm, and then the position of the center of gravity can be calculated through relevant algorithms.

[0030] S102: Obtain the position of the counterweight trolley of the balancing arm according to the lifting arm torque and the balancing arm torque to realize automatic adjustment of the counterweight.

[0031] Specifically, according to the boom moment M1 and the balance arm moment M2, we obtain: M1+G3*L3=M2+G4*L4.

[0032] Where G3 is the weight of the hoisted object, L3 is the distance from the center of gravity of the hoisted object to the center of the tower body; G4 is the weight of the counterweight trolley, L4 is the distance from the center of gravity of the counterweight trolley to the center of the tower body.

[0033] In the above parameters of this embodiment, the gravity of the hoisted object is obtained through the value of the lifting side tension sensor. When hoisting different weights, the system can automatically calculate the gravity of the hoisted object. The distance L3 from the center of gravity of the hoisted object to the center of the tower body can be calculated based on the value of the lifting side tension sensor and the displacement of the center of the displacement sensor; the gravity of the counterweight trolley is a known constant, so the above formula is used to dynamically calculate the sum of the hoisted object torque and the lifting arm torque, and then the difference with the balance arm torque. Then, based on the gravity of the counterweight trolley, the position of the counterweight trolley is calculated in reverse to achieve automatic adjustment of the counterweight. It can be said that after the self-balancing system of this embodiment is started, the system finally obtains the position of the counterweight trolley based on the value of the lifting side tension sensor and the displacement of the center of each displacement sensor, and grasps the offset of the center of gravity position during the hoisting process in real time, thereby ensuring the safety and stability of the hoisting operation. Moreover, the lifting arm torque and the balance arm torque can be calculated as constant values. The position of the counterweight trolley can be obtained by simply calculating the gravity of different hoisted objects and the distance from the center of gravity of the hoisted objects. The response speed is fast and the calculation is simple.

[0034] S103: When the difference between the lifting arm torque and the balance arm torque is greater than the high threshold, the balance arm counterweight inverter drives the AC motor to move at high speed; when the difference between the lifting arm torque and the balance arm torque is greater than the middle threshold, the balance arm counterweight inverter drives the AC motor to move at medium speed; when the difference between the lifting arm torque and the balance arm torque is greater than the low threshold and less than the middle threshold, the balance arm counterweight inverter drives the AC motor to move at low speed; when the difference between the lifting arm torque and the balance arm torque is less than the low threshold, the tower crane is in a balanced state and all moving components remain unchanged.

[0035] Specifically, the high threshold is 200 kN.m or less than -200 kN.m; the medium threshold is 75 kN.m or less than -75 kN.m; and the low threshold is 50 kN.m or less than -50 kN.m. The high-speed range of the motor is 28-32 Hz, the medium-speed range is 23-27 Hz, and the low-speed range is 18-22 Hz. More preferably, the high-speed range is 29-31 Hz, the medium-speed range is 24-26 Hz, and the low-speed range is 19-21 Hz.

[0036] When the difference between the boom torque and the counterweight torque exceeds a high threshold, the counterweight inverter drives the AC motor at high speed to control the movement of the counterweight on the counterweight arm. The position of the counterweight is calculated in step S102. If the weight of the hoisted object varies, the counterweight on the counterweight arm is adjusted to ensure the counterweight arm is balanced, preventing the crane from losing control due to an unstable center of gravity.

[0037] By setting different thresholds, this embodiment optimizes the accuracy of counterweight movement. For example, a low threshold allows the crane to fine-tune even minor deviations, improving positioning accuracy. A medium threshold is suitable for general counterweight adjustments, ensuring the crane remains balanced. A high threshold is suitable for situations requiring rapid or large-scale adjustments, improving adjustment speed and efficiency. Furthermore, the speed and response sensitivity of the counterweight AC motor can be controlled, increasing system stability and reducing the possibility of wobbling and swinging. Furthermore, setting different thresholds allows the system to adapt to different work scenarios and requirements. For example, a low threshold can be used for tasks requiring high precision and stability, while a high threshold can be used for tasks requiring rapid adjustment and high efficiency. This flexibility allows for adjustments based on specific needs, improving the crane's adaptability. Furthermore, when the threshold is low, the motor moves at a slower speed, reducing energy consumption. When the threshold is high, the motor moves at a faster speed, which increases energy consumption but allows for faster adjustment tasks and improved efficiency.

[0038] This embodiment controls the movement of the AC motor by comparing the difference between the boom torque and the counterarm torque with different thresholds. This provides stepless speed regulation, fast response, and millisecond-level computational output. This means that once the torque difference is detected to exceed the threshold, the motor can immediately start moving, enabling immediate adjustment of the balance state and improving the tower crane's response speed. Furthermore, the control accuracy and stability are high: by comparing the torque difference with the threshold to trigger motor movement, fine-tuning of the counterweight can be achieved. Furthermore, by real-time monitoring and adjustment of the counterweight, the tower crane's balance can be maintained, preventing sway or loss of control due to an unstable center of gravity. This helps improve the safety and stability of lifting operations. Furthermore, the system offers advantages such as good visibility, simple operation, high intelligence, convenient maintenance, and strong adaptability, enabling it to adapt to various working conditions and ensure safe operation of the tower crane.

[0039] S104: The main hook 4 is lifted, and the main hook inverter drives the main hook AC motor to slowly lift the hook. After the main hook is subjected to force, the self-balancing system repeats steps 101 to 103.

[0040] Specifically, during the lifting process of the main hook at the boom, the main hook inverter drives the main hook AC motor to control the movement of the main hook, the self-balancing system will continuously and dynamically calculate the position of the counterweight trolley, and compare the difference between the boom torque and the balance arm torque with the threshold to make the balance arm counterweight inverter drive the AC motor to select the appropriate speed to work, so that the counterweight trolley can adjust the distance and maintain the balance between the boom and the balance arm during the lifting process of the main hook.

[0041] S105: When the main hook lifts the object off the ground, the main hook inverter drives the main hook AC motor to lift the hook at normal speed, and the self-balancing system repeats steps 101 to 103 until a new equilibrium state is reached.

[0042] S106: When the main hook reaches a safe height, the main hook inverter drives the main hook AC motor to move forward or backward normally, and the self-balancing system repeats steps 101 to 103 until a new balance state is reached.

[0043] S107: During the self-balancing process, when the balancing arm counterweight trolley and the main hook 4 (i.e. the main hook trolley) reach the front and rear limits, they are protected by the displacement sensor limit, the travel switch limit and the mechanical limit respectively, and an alarm reminder will appear on the touch screen.

[0044] Among them, the displacement sensor limit belongs to the first level of protection of soft limit, the travel switch belongs to the second level of protection of hard limit, and the mechanical limit belongs to the third level of protection of extreme. Through these three protections, it can be ensured that the balance arm counterweight trolley and the main hook trolley will not exceed the safe range during movement, avoiding accidents and damage to the equipment. In addition, the displacement sensor limit and travel switch limit can provide high accuracy, accurately detect the position of the trolley, and trigger protective measures in time to avoid excessive adjustment or movement beyond the predetermined range, ensuring the stable operation of the equipment. The mechanical limit is implemented through physical structural design, which can play a role in preventing misoperation. Once the trolley reaches the mechanical limit, it will trigger the protective measures to prevent further movement or damage. In addition, even if a protective device fails or fails, the other protective devices still exist and can play a complementary role to ensure the restriction and protection of the trolley.

[0045] To sum up, on the one hand, the present invention obtains the position of the counterweight trolley through the lifting arm torque and the balance arm torque, and controls the balance arm counterweight inverter to drive the AC motor to move at a corresponding speed based on the comparison of the difference between the lifting arm torque and the balance arm torque with different thresholds, so that the counterweight trolley can be automatically adjusted, which greatly improves the response speed, stability and adjustment accuracy. It also has the advantages of good visibility, simple operation, simple algorithm, high degree of intelligence, convenient maintenance, strong adaptability, etc., and can adapt to various working conditions to ensure the safe operation of the tower crane; on the other hand, the position of the counterweight trolley is automatically adjusted during the process of main hook lifting, lifting objects off the ground, and lifting objects to a safe height, so as to ensure the safety and stability of the tower crane; furthermore, by setting three protections during the self-balancing process, the accuracy, safety and reliability of the counterweight trolley and the main hook trolley reaching the extreme positions can be greatly improved.

Claims

1. A balance control method based on the counterweight movement of a tower crane balance arm, characterized in that: The following steps are involved: S1: Obtain the lifting arm moment and balance arm moment of the tower crane; S2: Obtain the position of the counterweight trolley of the balancing arm according to the lifting arm torque and the balancing arm torque, and automatically adjust the position of the counterweight trolley according to the working state of the tower crane; S3: When the difference between the lifting arm torque and the balancing arm torque is greater than the high threshold, the balancing arm counterweight inverter drives the AC motor to move at high speed; when the difference between the lifting arm torque and the balancing arm torque is greater than the middle threshold, the balancing arm counterweight inverter drives the AC motor to move at medium speed; when the difference between the lifting arm torque and the balancing arm torque is greater than the low threshold and less than the middle threshold, the balancing arm counterweight inverter drives the AC motor to move at low speed; when the difference between the lifting arm torque and the balancing arm torque is less than the low threshold, the tower crane is in a balanced state and all moving components remain unchanged.

2. The balance control method based on the counterweight movement of the tower crane balance arm according to claim 1 is characterized in that: The method further comprises step S4: the main hook of the tower crane is lifted, and the main hook frequency converter drives the main hook AC motor to slowly lift the hook, and steps S1 to S3 are repeated until a new equilibrium state is reached.

3. The balance control method based on the counterweight movement of the tower crane balance arm according to claim 2 is characterized in that: The method also includes step S5: when the main hook lifts the object off the ground, the main hook frequency converter drives the main hook AC motor to lift the hook at a normal speed, and steps S1 to S3 are repeated until a new equilibrium state is reached.

4. The balance control method based on the counterweight movement of the tower crane balance arm according to claim 3 is characterized in that: It also includes step S6: when the main hook hoisting object reaches a safe height, the main hook trolley inverter drives the main hook AC motor to move forward or backward normally, and steps S1 to S3 are repeated until a new balance state is reached.

5. The balance control method based on the counterweight movement of the tower crane balance arm according to claim 4 is characterized in that: The step S7 is also included: during the self-balancing process, when the balancing arm counterweight trolley and the main hook reach the front and rear limits, they are protected by the displacement sensor limit, the travel switch limit and the mechanical limit respectively, and an alarm is sounded at the same time.

6. The balance control method based on the counterweight movement of the tower crane balance arm according to any one of claims 1 to 5, characterized in that: In step S1, the lifting arm moment M1 is obtained by the following formula: M1=G1*L1; the balance arm moment M2 is obtained by the following formula: M2=G2*L2; Where G1 is the gravity of the boom truss, L1 is the distance from the center of gravity of the boom to the center of the tower body; G2 is the gravity of the counter-arm truss, L2 is the distance from the center of gravity of the counter-arm to the center of the tower body.

7. The balance control method based on the counterweight movement of the tower crane balance arm according to claim 6 is characterized in that: In S2, according to the boom moment M1 and the balance arm moment M2, we obtain: M1+G3*L3=M2+G4*L4; In the formula, G3 is the gravity of the hoisted weight, L3 is the distance from the center of gravity of the hoisted weight to the center of the tower body; G4 is the gravity of the counterweight trolley, and L4 is the distance from the center of gravity of the counterweight trolley to the center of the tower body; the position of the counterweight trolley is calculated by dynamically calculating the sum of the moment of the hoisted weight and the moment of the crane arm, and the difference between the moment of the balance arm, and then based on the gravity of the counterweight trolley.

8. The balance control method based on the counterweight movement of the tower crane balance arm according to any one of claims 1 to 5, characterized in that: In S3, the high threshold is 200 kN.m or less than -200 kN.m; the middle threshold is 75 kN.m or less than -75 kN.m; and the low threshold is 50 kN.m or less than -50 kN.m.

9. The balance control method based on the counterweight movement of the tower crane balance arm according to any one of claims 1 to 5, characterized in that: In S3, the AC motor has a high-speed motion range of 28-32 Hz, a medium-speed motion range of 23-27 Hz, and a low-speed motion range of 18-22 Hz.

10. The balance control method based on the counterweight movement of the tower crane balance arm according to claim 7, characterized in that: The center of gravity positions L1 and L2 are calculated by the displacement data measured by the displacement sensors on the crane arm and the balance arm respectively; the gravity of the hoisted object is obtained by the value of the tension sensor on the crane side; the distance L3 from the center of gravity of the hoisted object to the center of the tower body is calculated based on the value of the tension sensor on the crane side and the displacement of the center of the displacement sensor.

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