WO2013086883A1

WO2013086883A1 - Method and system for controlling crane rotation

Info

Publication number: WO2013086883A1
Application number: PCT/CN2012/082078
Authority: WO
Inventors: 詹纯新; 刘权; 张建军; 李义; 李英智; 郭纪梅
Original assignee: 中联重科股份有限公司; 湖南中联重科专用车有限责任公司
Priority date: 2011-12-15
Filing date: 2012-09-26
Publication date: 2013-06-20
Also published as: CN102491178A; CN102491178B

Abstract

Disclosed are a method and a system for controlling crane rotation. The method and the system comprise: determining the rotational acceleration or resultant rotational force of the pendant ballast when the crane is rotating (S31); when the rotational acceleration is greater than a preset value thereof, or when the resultant rotational force is greater than a preset value thereof (S33), reducing the rotary speed of the rotational motor within a determined time period so as to reduce the rotational acceleration of the crane (S35). Using the method and the system aids in preventing the destructive influence of the kinetic energy of the pendant ballast on the overall or partial stability of the crane.

Description

TECHNICAL FIELD The present invention relates to the field of engineering machinery control technologies, and in particular, to a method and system for crane swing control. BACKGROUND OF THE INVENTION A crane is a common construction machine having a slewing platform and a lifting device capable of lifting a hoisting weight to a certain height to meet the needs of engineering construction. A simplified structure of a prior art crane is shown in Fig. 1, which is a schematic view of a simplified structure of a crane according to the prior art. The leg 11, the swivel platform 12, the boom 13, the boom head 14, the sling 15 connected between the boom head and the weight, and the sling 16 are shown in Fig. 1 . During the turning process, the slewing platform rotates about a straight line L which is perpendicular to the plane of revolution and passes through the center of revolution 0 of the slewing platform. In order to ensure the stability of the crane operation in the related art, a scheme for limiting the maximum swing speed of the crane is proposed. In carrying out the process of the present invention, the inventors have found that the kinetic energy of the hoisting weight also has a large influence on the stability of the crane during the hoisting operation of the crane. However, how to reduce the influence of the kinetic energy of the hoisting weight on the stability of the crane has not yet proposed an effective solution in the related art. SUMMARY OF THE INVENTION A primary object of the present invention is to provide a method and system for crane swing control to reduce the impact of kinetic energy of the hoisting weight on the stability of the crane. In order to achieve the above object, according to an aspect of the present invention, a method of crane swing control is provided. The method for slewing control of the crane of the present invention comprises: determining a slewing acceleration or a slewing force of the hoisting weight during the slewing process of the hoist; wherein the slewing acceleration is greater than a preset value of the slewing acceleration or the slewing force is greater than the slewing force In the case of a preset value, the rotation speed of the swing motor is lowered during the set period to lower the swing acceleration of the crane. Further, determining the swing acceleration of the crane during the turning process comprises: selecting a first time point and a second time point during the running of the swing operation command; determining the lifting weight according to the detected swing motor speed or the transmission gear speed Rotational line speed at the first time point and the second time point; The ratio of the difference between the rotational line speed of the first time point and the second time point and the time difference between the first time point and the second time point is taken as the rotational acceleration. Step, the preset value of the swing acceleration is determined as follows:

M _x + F _h co RM _y + F _h cos xH xtm

Determined according to inequality + + < [σ]

Maximum; where: N represents the axial force acting on the boom, the boom axial compression represents a stability factor indicating the boom axial stress, [mu] _[chi], represents the calculation of the cross-sectional X-axis and the strong axis of the minor axis The bending moment of the y-axis, indicating the tangential declination, /? Indicates the centripetal angle, H represents the distance from the center of gravity of the weight to the head of the boom when the sling is vertical, and indicates the bending modulus of the X-axis section of the strong axis determined by the compressed fiber, ^ indicates that the fiber is determined by the compression fiber The bending resistance of the y-axis section of the weak axis, F _3⁄4 represents the rotational force of the hoisting weight, [σ] represents the maximum stress allowed by the boom; the ratio of the maximum value to the mass of the hoisting weight is taken as The preset value of the swing acceleration. Further, determining the rotational joint force of the crane during the swinging process comprises: selecting a first time point and a second time point during the running of the swing operation command; according to the lifting weight at the first time point and the first The difference in the rotational line speed at the two time points determines the kinetic energy increment between the first time point and the second time point of the hoisting weight; according to the kinetic energy increment, the slewing line speed difference and the The time difference between the first time point and the second time point determines the combined rotational force. Further, the preset value of the rotational force is determined according to the following manner: According to Ν ( M _x + F _h cos R ( Μ,, + F^ cos xH xtan

- + + < [σ] calculates the maximum value, which is φΑ W.. w..

The maximum value is used as the preset value of the combined force of the swivel; wherein: N represents the axial force acting on the boom, and represents the stability coefficient of the arm shaft compression, ^ represents the axial stress of the boom, Μ _χ , represents the calculated section For the bending moment of the strong axis X axis and the weak axis y axis, it means the tangential declination, /? Indicates the centripetal angle, H represents the distance from the center of gravity of the weight to the head of the boom when the sling is vertical, ^ represents the flexural modulus of the X-axis section of the strong axis determined by the compressed fiber, ^ represents the fiber according to the compression Determine the bending modulus of the y-axis section of the weak axis, F _3⁄4 denotes the rotational force of the hoisting weight, and [σ] denotes the maximum stress allowed by the boom. According to another aspect of the present invention, a crane swing control system is provided. The crane swing control system of the present invention includes: a determination module for determining a swing acceleration or a swing joint force of a hoisting weight during a swing of the crane; a module, wherein the acceleration of the revolution is greater than the acceleration of the revolution In the case of a preset value, or in the case where the combined rotational force is greater than a preset value of the rotational combined force, reducing the rotational speed of the swing motor during the set period reduces the rotational acceleration of the crane. Further, the determining module is further configured to: select a first time point and a second time point during the running of the swing operation command; determine, according to the detected swing motor speed or the transmission gear speed, that the weight is in the a rotational line speed of the first time point and the second time point; a difference in the rotational linear velocity of the hoist at the first time point and the second time point, and the first time point and the The ratio of the time difference between the second time points is taken as the slew acceleration. Further, the determining module is further configured to: determine according to an inequality ≤[0"]

a maximum value, a ratio of a maximum value to a mass of the hoisting weight as a preset value of the slewing acceleration; wherein:

N indicates an axial force acting on the boom, the boom axial compression represents a stability factor, the boom ^ represents axial stress, [mu] _[chi], represents the calculation of Bending strength X-axis and the y-axis of the weak axis of Moment, indicating tangential declination, /? indicates centripetal angle, H indicates the distance from the center of gravity of the weight to the head of the boom when the sling is vertical, and ^ indicates the resistance of the X-axis section to the strong axis determined by the compressed fiber. The flexural modulus, ^ represents the flexural modulus of the weak-axis y-axis section determined by the compressed fiber, F _3⁄4 represents the rotational joint force of the hoisting weight, and [σ] represents the maximum allowable stress of the boom. Further, the determining module is further configured to: determine, according to a difference in the rotational line speed of the hoist at the first time point and the second time point, the hoisting weight at the first time point And a kinetic energy increment between the second time point; determining the slewing according to the kinetic energy increment, the slewing linear velocity difference, and a time difference between the first time point and the second time point Together. Further, the determining module is further configured to determine a preset value of the rotational force according to the following manner: according to the maximum value calculated by <[σ],

The maximum value is used as the preset value of the combined force of the swivel; wherein: N represents the axial force acting on the boom, and represents the stability coefficient of the arm shaft compression, ^ represents the axial stress of the boom, Μ _χ , represents the calculated section For the bending moment of the strong axis X axis and the weak axis y axis, it means the tangential declination, /? Indicates the centripetal angle, H represents the distance from the center of gravity of the weight to the head of the boom when the sling is vertical, ^ represents the flexural modulus of the X-axis section of the strong axis determined by the compressed fiber, ^ represents the fiber according to the compression Determine the bending modulus of the y-axis section of the weak axis, F _3⁄4 denotes the rotational force of the hoisting weight, and [σ] denotes the maximum stress allowed by the boom. According to the technical solution of the present invention, determining the rotational acceleration or the rotational combined force of the hoisting weight during the rotation of the crane, and then, if the rotational acceleration is greater than the preset value of the rotational acceleration, or when the rotational combined force is greater than the preset value of the rotational combined force, Decreasing the rotational speed of the swing motor during the set time period reduces the rotational acceleration of the crane, thereby realizing the automatic safety control of the working state control and avoiding the additional dynamic bending moment of the boom by the kinetic energy of the hoisting weight The impact of the crane has improved the safety of the crane operation. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are intended to provide a further understanding of the invention In the drawings: FIG. 1 is a schematic view showing a simplified structure of a crane according to the prior art; FIG. 2 is a schematic diagram showing a basic step of a method for controlling the swing of a crane according to an embodiment of the present invention; FIG. 3 is an embodiment of the present invention. FIG. 4 is a schematic view showing an ideal running trajectory and an actual running trajectory of a hoisting weight according to an embodiment of the present invention; FIG. 5 is a rotating plane related to an embodiment of the present invention; FIG. 6A is a schematic view showing the tangential force of the sling and the force in other directions according to the embodiment of the present invention; FIG. 6B is a schematic view showing the centripetal force and other directions of the sling according to the embodiment of the present invention. Figure 7 is a schematic view of a swing of a handle relating to an embodiment of the present invention; and Figure 8 is a schematic view showing the basic structure of a system for swing control of a crane according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. The invention will be described in detail below with reference to the drawings in conjunction with the embodiments. In the embodiment, the rotation speed of the slewing motor is controlled by determining whether the slewing acceleration or the slewing force of the hoisting weight is greater than a preset value during the slewing of the crane, and then the rotation speed of the slewing motor is decreased during the set period to thereby make the crane The slew acceleration is reduced. The basic process can specifically adopt the steps shown in FIG. 2 or FIG. 3. 2 is a schematic diagram of a basic step of a method for swing control of a crane according to an embodiment of the present invention. As shown in FIG. 2, the method mainly includes the following steps: Step S21: Determine the rotational acceleration of the hoisting weight during the rotation of the crane. Step S23: determining whether the swing acceleration of the hoisting weight is greater than the preset value of the swing acceleration, and if yes, proceeding to step S25, otherwise returning to step S21. Step S25: Decreasing the rotation speed of the swing motor during the set period of time reduces the swing acceleration of the crane. This step may return to step S21 as shown in FIG. 2. FIG. 3 is a schematic diagram of another basic step of the method for controlling the swing of the crane according to the embodiment of the present invention. As shown in FIG. 3, the method mainly includes the following steps: Step S31: Determine the combined force of the swing of the weight during the swing of the crane. Step S33: determining whether the combined force of the hoisting weight is greater than the preset value of the slewing force, and if yes, proceeding to step S35, otherwise returning to step S31. Step S35: Decreasing the rotation speed of the swing motor during the set period of time reduces the swing acceleration of the crane. This step may return to step S31, as shown in FIG. The combined rotational force in step S31 is the combined force of the centripetal force and the tangential force of the sling in the process of turning, the centripetal force is directed to the center of rotation, and the tangential force is tangential along the circumference of the revolution. The actual motion trajectory of the weight is a curve, which is the result of the combination of centripetal force and tangential force. Referring to Figures 4 through 6C, Figure 4 is a schematic illustration of an ideal trajectory and actual trajectory of a sling in accordance with an embodiment of the present invention. In Fig. 4, 41 denotes the theoretical running trajectory of the hoisting weight, which is a circle, and the center 42 is the center of rotation of the crane. Under actual operating conditions, the hoisting weight can travel from the starting point 43 along the trajectory 44 to the end point 45, and the trajectory 44 forms an irregular curve due to the swaying of the hoisting weight. Fig. 5 is a schematic view showing a state in which a plane of revolution is concerned with an embodiment of the present invention. In Fig. 5, 51 denotes the theoretical running trajectory of the hoisting weight, which is a circle, and the center 52 is the center of rotation of the crane. Without considering the swing of the hoisting weight, the hoisting weight theoretical position 54 coincides with the boom head center 53 in a plan view (as shown in Figure 5). However, due to the swing of the weight, its actual position is 57, so the displacements 55 and 56 are formed in the normal and tangential directions of the trajectory 51. Due to the existence of these two displacements, the actual position and the theoretical position of the weight are respectively formed. The centripetal angle formed by the normal direction of the locus 51 and the tangential declination formed in the tangential direction of the locus 51. Fig. 6A is a schematic view showing the tangential force of the sling and the force in other directions relating to the embodiment of the present invention. 6A shows the crane leg 61, the swivel 62, the theoretical swivel track 63, the sling 64, the sling 65, the boom 66, and the tangential angle 67. Fig. 6A also shows the weight centripetal force F _r , the weight tangential force F _a , the weight revolving force F _h synthesized by the two, and the gravity G received by the weight. Fig. 6B is a schematic view showing the force of the centripetal force and other directions of the sling according to the embodiment of the present invention. Figure 6B shows the crane leg 61, the swivel 62, the boom head The vertical distance 63 to the center of gravity of the hoisting weight, the hoisting weight 64, the sling 65, the boom 66, the sling radius of rotation 68, and the centripetal angle 69. FIG. 6B also shows the weight centripetal force F _r and the weight tangential force F _a , and the weight revolving force F _h synthesized by the two. There is also gravity G that the weight is subjected to. The preset value of the rotational force can be determined according to the following inequality, which represents the combined force of the rotation:

The ratio of the maximum value to the mass of the hoisting weight can be used as a preset value of the yaw acceleration. The meanings of the letters in formula (1) are consistent with the GB/T3811-2008 Crane Design Specification. Specifically, the meanings of the letters in this embodiment are as follows:

N represents the axial force acting on the boom, indicating the stability factor of the boom axis compression, ^ indicates the axial stress of the boom, Μ _χ , Λ indicates the calculated axis on the strong axis (X axis) and the weak axis ( The bending moment of the y-axis), "represents the tangential declination, /? represents the centripetal angle, H represents the distance from the center of gravity of the weight to the head of the boom when the sling is vertical, ^ represents the strong force determined by the compressed fiber Shaft (X-axis) cross-section buckling modulus, ^ indicates the bending resistance modulus of the weak axis (y-axis) section determined by the compressed fiber, F _3⁄4 indicates the rotational force of the hoisting weight, and [σ] indicates the boom The maximum stress is allowed. The units of the above quantities can be used in the international unit system or other unit system. When determining the acceleration of the crane during the turning process, the first time point can be selected first during the rotation operation command. a second time point; then determining a rotational line speed of the hoist at the first time point and the second time point according to the detected slewing motor speed or the transmission gear speed; hoisting the weight at the first time point and the second time point Rotational line speed difference and The ratio of the time difference between a time point and the second time point is taken as the gyro acceleration. The slewing operation command is usually given by the handle. Fig. 7 is a schematic view of the handle swing associated with the embodiment of the present invention. The handle 71, the running path 72 of the handle and the angle 73 formed thereby, and in actual operation, the handle can stay at any intermediate position within the entire range, such as position 74. The stroke of the handle can be projected on the S axis in the horizontal direction. The handle stroke is represented by coordinates on the S-axis, such as Α and 。, as shown in Fig. 7. In the related art, the handle is toggled by the driver to have a certain swing angle, and the magnitude of the angle determines the current output by the handle. The current is used to control the displacement of the rotary pump, that is, the rotational speed of the rotary motor is determined by the swing angle of the handle. However, in this embodiment, if the handle is given the rotary operation command, the handle swing The angle of rotation no longer determines the rotational speed of the swing motor, but is controlled by the controller using the control method of the embodiment. If the handle in the related art is used, Regardless of the current output, as long as there is a current output, it is considered to be a single output. One rotary operation command, without the command of the motor speed (ie, the magnitude of the current), so that the current output period is the duration of the swing operation command. Therefore, the handle can also be changed to other parts that operate, such as buttons, pedals, etc., and the output is also a single rotary operation command. When determining the swinging force of the crane during the turning process, the first time point and the second time point may be selected first during the running of the turning operation command; according to the rotation of the lifting object at the first time point and the second time point The line speed difference determines the kinetic energy increment between the first time point and the second time point of the hoisting weight; according to the kinetic energy increment, the slewing line speed difference, and the time difference between the first time point and the second time point The value determines the rotational force. Specifically, the following formula can be used for calculation:

_A "MAV ² JV

(2)

2 2R

V = πχη — ( 3 )

30

MR

(4)

g

AE _k = F _m x AVxAT ( 5 ) The simultaneous joint force (2) to (5) can be used to calculate the rotational joint force, which is expressed in the formula. The meanings of the other letters in the formulas are as follows: Indicates the kinetic energy increment of the hoisting weight at the first time point and the second time point, M represents the weight of the hoisting weight, represents the sling weight linear velocity, and R represents the hoisting weight The radius of gyration of the object, g represents the acceleration of gravity, and represents the speed difference between the first time point and the second time point of the hoisting object, and ΔΓ represents the time difference between the first time point and the second time point, “representing the rotation speed of the slewing mechanism. The basic structure of the system for crane swing control in the embodiment of the present invention will be described below. The system can be implemented with a crane controller. Figure 8 is a schematic illustration of the basic structure of a system for crane swing control in accordance with an embodiment of the present invention. As shown in FIG. 8, the crane slewing control system 80 mainly includes a determining module 81 and a control module 82, wherein the determining module 81 is configured to determine a slewing acceleration or a slewing force of the hoisting weight during the hoisting of the crane; the control module 82 is used for When the swing acceleration is greater than the preset value of the swing acceleration, or when the swing joint force is greater than the preset value of the swing joint force, the rotation speed of the swing motor is lowered to lower the swing speed of the crane. The determining module 81 is further configured to select a first time point and a second time point during the running of the swing operation command; determining the lifting weight at the first time point according to the detected swing motor speed or the transmission gear speed The rotational linear velocity at the second time point; the ratio of the rotational linear velocity difference between the first time point and the second time point and the time difference between the first time point and the second time point as the rotational acceleration . The determining module 81 can also be used for the maximum value determined according to the formula (1), and the ratio of the maximum value to the mass of the hoisting weight is used as the swing acceleration preset value. The determining module 81 is further configured to determine, according to the difference in the rotational line speed of the hoist at the first time point and the second time point, the kinetic energy increment between the first time point and the second time point of the hoisting weight; The amount, the rotational line speed difference, and the time difference between the first time point and the second time point determine the rotational resultant force. The determining module 81 can also be used to determine the rotational force preset value according to the formula (1). According to the technical solution of the present invention, determining the rotational acceleration or the rotational combined force of the hoisting weight during the rotation of the crane, and then, if the rotational acceleration is greater than the preset value of the rotational acceleration, or when the rotational combined force is greater than the preset value of the rotational combined force, Decreasing the rotational speed of the swing motor during the set time period reduces the rotational acceleration of the crane, thereby realizing the automatic safety control of the working state control and avoiding the additional dynamic bending moment of the boom by the kinetic energy of the hoisting weight The impact of the crane has improved the safety of the crane operation. Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device, or they may be separately fabricated into individual integrated circuit modules, or they may be Multiple modules or steps are made into a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

A method for controlling a swing of a crane, comprising:

Determining the rotational acceleration or the combined force of the hoisting weight during the rotation of the crane;

In the case where the rotational acceleration is greater than a preset value of the rotational acceleration or in the case where the rotational combined force is greater than a preset value of the rotational combined force, reducing the rotational speed of the swing motor during the set period reduces the rotational acceleration of the crane. The method of claim 1 wherein determining the rotational acceleration of the crane during the swing comprises:

Selecting a first time point and a second time point during the running of the swing operation command; determining, according to the detected swing motor speed or the transmission gear speed, the rotation of the weight at the first time point and the second time point Line speed;

Taking the ratio of the difference between the rotational linear velocity of the hoisting weight at the first time point and the second time point and the time difference between the first time point and the second time point as Describe the acceleration of rotation. The method according to claim 1 or 2, wherein the preset value of the swing acceleration is determined according to the following manner: according to the inequality

The maximum value of F _3⁄4 ; where: N represents the axial force acting on the boom, represents the stability factor of the boom axial compression, represents the axial stress of the boom, Μ _χ , represents the X-axis of the strong axis on the calculated section And the bending moment of the y-axis of the weak axis, indicating the tangential declination, /? Indicates the centripetal angle, H represents the distance from the center of gravity of the weight to the head of the boom when the sling is vertical, and indicates the bending modulus of the X-axis section of the strong axis determined by the compressed fiber, and W _y represents the fiber according to the compression. Determine the bending modulus of the y-axis section of the weak axis, F _3⁄4 denotes the rotational force of the hoisting weight, [σ] denotes the maximum stress allowed by the boom; the ratio of the maximum value to the mass of the hoisting weight is taken as The preset value of the swing acceleration. The method of claim 1 wherein determining the rotational resultant of the crane during the swing comprises:

Selecting the first time point and the second time point during the duration of the swing operation instruction; Determining the kinetic energy increment of the hoisting object between the first time point and the second time point according to a difference in the rotational line speed of the hoisting weight at the first time point and the second time point ;

The rotational resultant force is determined based on the kinetic energy increment, the rotational linear velocity difference, and a time difference between the first time point and the second time point. The method according to claim 1 or 4, wherein the preset value of the combined rotational force is determined according to the following manner: φΑ calculated according to ^; + ≤ ]

The maximum value, the maximum value is used as the preset value of the rotating force; wherein: N represents the axial force acting on the boom, and represents the stability coefficient of the arm shaft compression, ^ represents the axial stress of the boom, M _x , M _y represent the bending moment of the strong axis x axis and the weak axis y axis on the calculated section, indicating the tangential declination, /? indicates the centripetal angle, and H indicates the center of gravity of the weight when the sling is vertical to the boom The distance between the heads, ^ represents the flexural modulus of the X-axis section of the strong axis determined by the compressed fiber, ^ represents the flexural modulus of the y-axis section of the weak axis determined by the compressed fiber, and F _3⁄4 represents the sling The combined force of the object, [σ] indicates that the boom allows maximum stress. A system for crane swing control, comprising:

a determining module for determining a rotational acceleration or a rotational joint force of the hoisting weight during the swinging of the crane;

a control module, configured to reduce the rotation speed of the swing motor in the set time period when the swing acceleration is greater than a preset value of the swing acceleration, or in a case where the swing joint force is greater than a preset value of the swing joint force The rotational acceleration is reduced. The system according to claim 6, wherein the determining module is further configured to: select a first time point and a second time point during the duration of the rotation operation command; and the rotation speed or the transmission gear according to the detection The rotational speed determines a rotational linear velocity of the hoist at the first time point and the second time point;

Taking the ratio of the difference between the rotational linear velocity of the hoisting weight at the first time point and the second time point and the time difference between the first time point and the second time point as Describe the acceleration of rotation. The system according to claim 6 or 7, wherein the determining module is further configured to: M _x + F _h co R

According to inequality - + +

_Determining a maximum value of F _3⁄4 , a ratio of a maximum value to a mass of the hoisting weight as a preset value of the slewing acceleration;

Where: N represents the axial force acting on the boom, the boom axial compression represents a stability factor, the boom ^ represents axial stress, [mu] _[chi], represents the calculation of the cross-sectional X-axis and the strong axis of the minor axis y-axis The bending moment, indicating the tangential declination, /? Indicates the centripetal angle, H represents the distance from the center of gravity of the weight to the head of the boom when the sling is vertical, ^ represents the flexural modulus of the X-axis section of the strong axis determined by the compressed fiber, ^ represents the fiber according to the compression Determine the bending modulus of the y-axis section of the weak axis, F _3⁄4 denotes the rotational force of the hoisting weight, and [σ] denotes the maximum stress allowed by the boom. The system according to claim 6, wherein the determining module is further configured to:

Determining the kinetic energy increment of the hoisting object between the first time point and the second time point according to a difference in the rotational line speed of the hoisting weight at the first time point and the second time point ;

The rotational resultant force is determined based on the kinetic energy increment, the rotational linear velocity difference, and a time difference between the first time point and the second time point.

The method according to claim 6 or 9, wherein the determining module is further configured to determine a preset value of the rotational force according to the following manner:

M _x + F _h co RM _y + F _h cosorxHxtanor

φΑ calculated according to ^; + + ≤ ]

The maximum value is the preset value of the combined force of the swivel; wherein: N represents the axial force acting on the boom, and represents the stability coefficient of the arm shaft compression, ^ represents the axial stress of the boom, Μ _χ , indicates the bending moment of the strong axis X axis and the weak axis y axis on the calculated section, indicating the tangential declination, /? Indicates the centripetal angle, H represents the distance from the center of gravity of the weight to the head of the boom when the sling is vertical, ^ represents the flexural modulus of the X-axis section of the strong axis determined by the compressed fiber, ^ represents the fiber according to the compression Determine the bending modulus of the y-axis section of the weak axis, F _3⁄4 denotes the rotational force of the hoisting weight, and [σ] denotes the maximum stress allowed by the boom.