Early warning method for time-varying operation of automobile crane

Abstract

The invention discloses an early warning method for time-varying operation of an automobile crane. According to the scheme, the early warning method comprises the following steps: acquiring coordinates (xcop, ycop) of a pressure center CoP of a to-be-analyzed automobile crane in a working state under a reference coordinate system; monitoring in real time to obtain a zero moment point (xzmp, yzmp) of the automobile crane to be analyzed; calculating a real-time first ratio Kx and a real-time second ratio Ky of the to-be-analyzed truck crane in a working state according to the following formula: # imgabs0 #, obtaining a maximum value K = max (Kx, Ky) in the first ratio Kx and the second ratio Ky, when the maximum value K is less than or equal to a numerical value 1, not performing early warning on the to-be-analyzed truck crane, and when the maximum value K is less than or equal to a numerical value 2, not performing early warning on the to-be-analyzed truck crane. When the maximum value K is larger than the numerical value 1 and smaller than or equal to a preset threshold value, an early warning requiring low-speed operation is sent out to the to-be-analyzed automobile crane, and when the maximum value K is larger than the preset threshold value, an operation stopping warning is sent out to the to-be-analyzed automobile crane.

Description

Technical Field

[0001] The invention relates to the technical field of crane overturning hazard prediction, and in particular to an early warning method for time-varying operation of a truck crane. Background Art

[0002] Truck cranes are widely used, highly maneuverable, and can be easily moved to other locations. Therefore, they are suitable for lifting heavy components and short-cycle operations. However, truck cranes have high requirements for roads and sites during operation, and are prone to overall overturning, causing property losses and personal injuries. Therefore, it is necessary to study the anti-overturning stability of truck cranes to ensure the safety of the operation process and reduce the risk of accidents.

[0003] During the lifting, luffing, slewing and combination operations of the truck crane, the migration of the center of mass of the superstructure will interfere with the posture stability of the outrigger system and the outrigger load distribution in real time. Moreover, due to complex nonlinear and time-varying factors, the current stability monitoring system is not very effective in diagnosing the mechanical properties of the truck crane. For example, uncontrollable factors such as wind speed load, hanging weight swing and poor ground conditions. Therefore, the monitoring system has theoretical and technical defects, which makes it difficult to avoid overturning accidents under certain conditions. Especially in the operation process, it is inevitable to encounter confined spaces and situations where the outriggers cannot be fully opened. The maximum lifting torque in this case is not easy to determine, which increases the risk of overturning. Therefore, it is necessary to provide an anti-overturning warning method that can monitor the truck crane in a working state. Summary of the invention

[0004] The present invention provides a method for overcoming at least one technical problem existing in the prior art.

[0005] An embodiment of the present invention provides an early warning method for time-varying operation of a truck crane, comprising:

[0006] S1. Obtain the coordinates xcop, ycop) of the pressure center CoP of the truck crane to be analyzed in the working state in the reference coordinate system, specifically including:

[0007] A pressure sensor is pre-installed at the end of each outrigger of the truck crane to be analyzed that contacts the ground. The pressure sensor is used to measure the pressure of the outrigger at the corresponding position on the contacted ground. The pressure at the end of each outrigger of the truck crane to be analyzed that contacts the ground is obtained based on the pressure sensor, and the coordinates (xcop, ycop) of the pressure center CoP in the reference coordinate system are calculated by the following formula:

[0008]

[0009] Among them, the symbol xcop The horizontal coordinate of the center of pressure CoP is y cop represents the ordinate of the pressure center CoP, the symbol m represents the total number of outriggers of the truck crane to be analyzed, and the symbol x i Indicates the horizontal coordinate of the installation position of the i-th pressure sensor, symbol y i Indicates the ordinate of the installation position of the i-th pressure sensor, symbol P i represents the pressure value monitored by the i-th pressure sensor, where 1≤i≤m;

[0010] S2, real-time monitoring to obtain the zero moment point (x zmp ,y zmp ), including:

[0011] Get the mass m of the i-th component of the truck crane to be analyzed i , the centroid coordinate x of the i-th component i ,y i ,z i ), and the acceleration of the center of mass of the ith component in the x, y, and z directions Then the resultant force F of the gravity and inertia force of the truck crane to be analyzed is expressed as:

[0012]

[0013] Wherein, the symbol g represents the acceleration of gravity, and the moment M of the resultant force F on each coordinate axis is expressed as:

[0014]

[0015] Wherein, the symbol n represents the number of components of the truck crane to be analyzed. The resultant force F is moved from the origin of the reference coordinate system to the zero moment point ZMP, where the resultant moment on the X and Y axes is zero, then:

[0016]

[0017] get:

[0018]

[0019] S3, calculate the first ratio K of the truck crane to be analyzed in real time when it is in working state according to the following formula: x and the second ratio K y :

[0020]

[0021] Get the first ratio Kx and the second ratio K y The maximum value K=max(K x ,K y ), when the maximum value K is less than or equal to the value 1, no warning is issued to the truck crane to be analyzed; when the maximum value K is greater than the value 1 and less than or equal to the predetermined threshold, a warning is issued to the truck crane to be analyzed to require low-speed operation; when the maximum value K is greater than the predetermined threshold, a warning to stop operation is issued to the truck crane to be analyzed.

[0022] Preferably, each of the pressure sensors in step S1 is communicatively connected to a wireless transmission module, and the wireless transmission module transmits the collected pressure data to a data receiving terminal in a wireless manner.

[0023] Preferably, the numerical value of the predetermined threshold is between 1.1 and 1.3.

[0024] At least one embodiment of this specification can achieve the following beneficial effects: In the technical solution of this application, the center of pressure CoP refers to a point representing the overall force balance state of the crane obtained by calculating the data collected by the outrigger pressure sensors during the operation of the truck crane, which is used to reflect the concentrated position of the pressure borne by the outrigger of the crane. The ZMP, on the other hand, refers to the point at a certain moment where the resultant force of all the forces acting on the crane (including the resultant force of gravity, external forces, and inertial forces) has no horizontal component on the support surface, and it is the key point reflecting the motion stability of the truck crane. Considering that the truck crane may experience actions such as hoisting and slewing, luffing, telescoping of the boom, and telescoping of the outriggers during actual operation, the position of its center of gravity and the magnitude of the acceleration are changing all the time. By comparing the center of pressure CoP with the zero moment point ZMP, the dynamic stability of the truck crane can be evaluated. Among them, the center of pressure CoP is the center of pressure of the outriggers measured by the outrigger pressure sensors, and its value reflects the actual pressure distribution of each outrigger of the truck crane during operation, which can reflect the static stability of the truck crane. In the technical solution of this application, by comparing the relative positions of CoP and ZMP, the anti-overturning stability of the crane can be judged through the calculated K value (Kx or Ky). The K value is the ratio of the ZMP coordinates to the CoP coordinates. Assuming that the predetermined threshold is set to 1.3, thus in the technical solution of this application, when K ≤ 1, it indicates that ZMP is within or coincides with CoP, indicating that the truck crane is in a stable state and can operate normally; when 1 < K ≤ 1.3, it indicates that the stability is reduced, and low-speed operation should be adopted to ensure safety; when K > 1.3, it means that ZMP is far beyond the CoP range, and there is a serious risk of overturning, and the operation should be stopped immediately at this time. This comparison method combines the influence of static stability and dynamic loads, can more accurately reflect the actual stable state of the truck crane under complex working conditions, provides timely warning information for the operator, and effectively avoids the occurrence of overturning accidents. At the same time, compared with the existing solution mentioned above where an alarm or forced braking will be triggered when the measured lifting capacity exceeds the maximum lifting capacity, this solution monitors the overturning of the truck crane more precisely. That is, when K ≤ 1, the truck crane is considered to be in a stable state and can operate normally. When 1 < K ≤ 1.3, it indicates that the stability is reduced, and low-speed operation should be adopted to ensure safety. That is, when the K value is detected to be greater than 1, instead of directly issuing a warning to stop the operation, a warning to perform low-speed operation is issued, and a warning to stop the operation immediately is issued only when K > 1.3. This solution can monitor the anti-overturning trend of the truck crane in real time and make more effective use of the truck crane on the premise of ensuring safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A calculation model for the overturning stability of a truck crane established in an early warning method for time-varying operation of a truck crane provided in an embodiment of this specification;

[0027] Figure 2 A schematic diagram comparing the effect of an early warning method for time-varying operation of a truck crane provided in an embodiment of this specification with the prior art. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of one or more embodiments of this specification clearer, the technical solutions of one or more embodiments of this specification will be clearly and completely described below in combination with the specific embodiments of this specification and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of one or more embodiments of this specification.

[0029] It should be understood that although the terms first, second, third, etc. may be used in this application document to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other.

[0030] A truck crane is a jib crane installed on an ordinary or special automobile chassis. During operation, the load of the entire machine is transferred to the foundation through four outriggers. During the lifting, luffing, slewing and combined operations of the truck crane, the center of mass migration of the superstructure will interfere with the posture stability of the outrigger system and the outrigger load distribution in real time.

[0031] At present, among the relevant schemes for the research on the anti-overturning property of automobile cranes, some schemes consider the influence of the outrigger pressure, but because the pressure changes slowly and the reaction is delayed when measuring the outrigger pressure, the transient acceleration cannot be obtained in time, so it is not sensitive enough. Some schemes consider measuring the acceleration of the running parts and calculating the change of the zero moment point ZMP, but they assume that the foundation is a rigid structure, that is, it is assumed that the ground does not elastically deform under the load transmitted by the outriggers. However, when the automobile crane is actually working, the ground is deformed, which will affect the outrigger pressure, so the calculated value of this scheme is not accurate enough. In some schemes, the actual arm length, actual luffing angle and actual slewing angle are measured respectively by the boom length sensor, the luffing cylinder lifting angle sensor and the slewing angle sensor, and then the acceleration is calculated to obtain the zero moment point ZMP, and the maximum lifting weight of each working condition is derived. However, this method of measuring acceleration is to measure the speed and then obtain the acceleration by time derivative. It is not as fast and sensitive as the method of directly measuring the acceleration by IMU. Therefore, the zero moment point ZMP measured by this scheme is too small, and the maximum lifting weight calculated theoretically is too large, which will cause misjudgment and false alarm. At the same time, these schemes also lack the influence of wind load on the crane. Wind load increases the risk of overturning and reduces stability, so the judgment result is not accurate enough.

[0032] In order to solve the technical problems existing in the prior art, a method for predicting the overturning danger of a crane provided in the embodiment of the specification will be specifically described in combination with the accompanying drawings. The technical solution of the present application proposes an early warning method for time-varying operation of a truck crane, comprising the following steps:

[0033] Step S1: Obtain the coordinates (x cop ,y cop ), which may include:

[0034] A pressure sensor is pre-installed at the end of each outrigger of the truck crane to be analyzed that contacts the ground. The pressure sensor is used to measure the pressure of the outrigger at the corresponding position on the ground it contacts. The pressure at the end of each outrigger of the truck crane to be analyzed that contacts the ground is obtained based on the pressure sensor. The coordinates of the pressure center CoP in the reference coordinate system (x cop ,y cop ):

[0035]

[0036] Among them, the symbol x cop The horizontal coordinate of the center of pressure CoP, symbol y cop The ordinate represents the center of pressure CoP, the symbol m represents the total number of outriggers of the truck crane to be analyzed, and the symbol x iIndicates the horizontal coordinate of the installation position of the i-th pressure sensor, symbol y i Indicates the ordinate of the installation position of the i-th pressure sensor, symbol P i Represents the pressure value monitored by the i-th pressure sensor, where 1≤i≤m.

[0037] Step S2: Real-time monitoring to obtain the zero moment point (x zmp ,y zmp ), including:

[0038] Get the mass m of the i-th component of the truck crane to be analyzed i , the centroid coordinates of the ith component (x i ,y i ,z i ), and the acceleration of the center of mass of the ith component in the x, y, and z directions Then the resultant force F of the gravity and inertia force of the truck crane to be analyzed is expressed as:

[0039]

[0040] Wherein, the symbol g represents the acceleration of gravity, and the moment M of the resultant force F on each coordinate axis is expressed as:

[0041]

[0042] The symbol n represents the number of components of the truck crane to be analyzed. Move the resultant force F from the origin of the reference coordinate system to the zero moment point ZMP. At the ZMP point, the resultant moment on the X and Y axes is zero, then:

[0043]

[0044] get:

[0045]

[0046] In this step, it is taken into account that when the truck crane is in operation, rotation, luffing and lifting movements will occur. The speed changes of these movements will cause inertia forces to be generated in the main moving parts including the upper vehicle, the boom, the counterweight, the hook and the weight, thereby reducing the dynamic stability of the entire crane. The key parts that affect the operation stability may mainly include the upper vehicle, the lower vehicle, the counterweight, the boom, the hook and the weight, which are represented by i (i=1, 2, 3, ..., n).

[0047] Step S3: Calculate the first ratio K of the truck crane to be analyzed in real time when it is in working state according to the following formula: x and the second ratio K y :

[0048]

[0049] Get the first ratio K x and the second ratio K y The maximum value K=max(K x ,K y ), when the maximum value K is less than or equal to the value 1, no warning is issued to the truck crane to be analyzed; when the maximum value K is greater than the value 1 and less than or equal to the predetermined threshold, a warning is issued to the truck crane to require low-speed operation; when the maximum value K is greater than the predetermined threshold, a warning to stop the operation is issued to the truck crane to be analyzed.

[0050] In a further optimization scheme, each of the pressure sensors in step S1 is communicatively connected to a wireless transmission module, and the wireless transmission module transmits the collected pressure data to a data receiving terminal in a wireless manner.

[0051] In a further optimization scheme, the numerical value of the predetermined threshold may be between 1.1 and 1.3.

[0052] The solution proposed in the technical solution of this application can measure the impact of wind load on the crane. The main principle is: the wind load acts on the entire truck crane, which will generate lateral force, thereby changing the outrigger pressure value. The technical solution of this application can measure the change of outrigger pressure through the outrigger pressure sensor to obtain the COP under the action of wind load. Wind load causes moving parts to generate inertial force, such as the swing of the hanging object. The technical solution of this application can obtain acceleration through the IMU on the hook, calculate the inertial force, and obtain the zero moment point ZMP under the action of wind load.

[0053] The technical solution of this application also makes scientific and reasonable segmentation in the judgment results. In the traditional method, a warning value is generally set. Once the warning value is exceeded, an alarm is issued and the operation is stopped. For example, some solutions will alarm or force braking once the measured lifting weight exceeds the maximum lifting weight, thereby stopping the operation. The technical solution of this application sets 2 warning values, which are divided into three areas: safe operation, low-speed operation and stopped operation. The added low-speed operation area gives full play to the reserve lifting capacity of the truck crane.

[0054] For example Figure 2 In the traditional algorithm, the safety area is the rectangle formed by the four outrigger support points, divided by the safety factor K. Whether it is CoP or ZMP, once the safety area is exceeded, an alarm will be sounded and the operation will be stopped. As shown in the figure, the ZMP point is outside the safety area and cannot be operated. In the technical solution of the present application, by adding the measurement of CoP and comparing it with ZMP, it is judged as a low-speed operation, thereby making full use of the reserve lifting capacity of the truck crane.

[0055] In summary, due to complex nonlinear and time-varying factors, existing truck crane stability monitoring solutions are not very effective in diagnosing the mechanical properties of truck cranes. They do not consider the impact of uncontrollable factors such as wind speed load, load swing and harsh ground conditions on the stability of the crane, are inconsistent with the actual working conditions of the truck crane, or do not take into account both safety and efficiency.

[0056] In a possible technical solution, the real-time center of mass position of each part of the truck crane in the working state can be obtained by combining theoretical modeling and actual measurement. Specifically, first, according to the structure and lifting conditions of the truck crane, a theoretical model is established to determine the mass distribution of each component (such as the upper body, boom, heavy objects, etc.). Then, a variety of sensors are installed at the key parts of the truck crane, including but not limited to length / angle sensors, three-pulley sensors, levels, anemometers and monitoring instruments. Among them, the length / angle sensor is used to monitor the length and rotation angle of the boom, and the three-pulley sensor monitors the dynamic tension of the rope to indirectly reflect the lifting state. The level ensures the leveling of the whole vehicle. Although it does not directly measure the center of mass, it is the basis for stability assessment. The anemometer and monitoring instrument provide environmental and operating parameters to assist in understanding the dynamic working conditions. In actual operation, the above sensors are used to monitor the mass of the hanging object (indirectly calculated by the tension of the three-pulley sensor), the acceleration of the boom and the rotating body and other motion parameters in real time. Then, combining the data collected by the sensor and the pre-set crane structural parameters, the dynamics principle is applied to calculate the instantaneous position and acceleration of each part (including the hoisted object) under different working conditions. Using this information, the real-time center of mass position of each part is calculated according to the center of mass coordinate formula. Finally, a comprehensive analysis is performed, that is, the real-time center of mass positions of all components are combined to obtain the overall center of mass position of the entire truck crane under a specific working state, which is crucial for evaluating its anti-overturning stability.

[0057] In the technical solution of this application, the center of pressure CoP refers to a point obtained by calculating the data collected by the outrigger pressure sensors during the operation of a truck crane, which represents the overall force balance state of the crane and reflects the concentrated position of the pressure borne by the outriggers of the crane. The ZMP, on the other hand, refers to the point at which, at a certain moment, the resultant force of all the forces acting on the crane (including the combined force of gravity, external forces, and inertial forces) has no horizontal component on the support surface, and it is a key point reflecting the motion stability of the truck crane. Considering that a truck crane may experience actions such as hoisting and slewing, luffing, telescoping of the boom, and telescoping of the outriggers during actual operation, the position of its center of gravity and the magnitude of the acceleration are constantly changing. By comparing the center of pressure CoP with the zero moment point ZMP, the dynamic stability of the truck crane is evaluated. Among them, the center of pressure CoP is the center of pressure of the outriggers measured by the outrigger pressure sensors, and its value reflects the actual pressure distribution borne by each outrigger of the truck crane during operation, and can reflect the static stability of the truck crane. In the technical solution of this application, by comparing the relative positions of CoP and ZMP, the anti-overturning stability of the crane can be judged through the calculated K value (Kx or Ky). The K value is the ratio of the ZMP coordinates to the CoP coordinates. Assuming that the preset threshold is set to 1.3, thus in the technical solution of this application, when K ≤ 1, it indicates that the ZMP is within or coincides with the CoP, indicating that the truck crane is in a stable state and can operate normally; when 1 < K ≤ 1.3, it indicates that the stability is reduced, and low-speed operation should be adopted to ensure safety; when K > 1.3, it means that the ZMP is far beyond the CoP range, there is a serious risk of overturning, and the operation should be stopped immediately at this time. This comparison method combines the influence of static stability and dynamic loads, can more accurately reflect the actual stable state of the truck crane under complex working conditions, provides timely warning information for the operator, and effectively avoids the occurrence of overturning accidents. At the same time, compared with the existing solution mentioned above, in which an alarm or forced braking will be triggered when the measured lifting capacity exceeds the maximum lifting capacity, this solution monitors the overturning of the truck crane more precisely. That is, when K ≤ 1, it is considered that the truck crane is in a stable state and can operate normally; when 1 < K ≤ 1.3, it indicates that the stability is reduced, and low-speed operation should be adopted to ensure safety. That is, when the K value is detected to be greater than 1, instead of directly issuing a warning to stop the operation, a warning to perform low-speed operation is issued, and a warning to stop the operation immediately is issued only when K > 1.3. This solution can monitor the anti-overturning trend of the truck crane in real time and make more effective use of the truck crane on the premise of ensuring safety.

[0058] Figure 1A calculation model for the overturning stability of a truck crane is established. For the convenience of calculation, it is assumed that the main body and the boom of the truck crane are rigid bodies, and the hoisted object is regarded as a mass point. The distance between the center lines of the outriggers is ignored; the center of gravity of each section of the boom is ignored to be located at the geometric center of the boom, and the friction torque generated during the rotation process is ignored. During the hoisting operation, the truck crane is supported by four outriggers. Figure 1 The meanings of the symbols in are as follows: Symbol G d Indicates the mass of the vehicle, unit: kg, symbol G p Indicates the mass of the counterweight, unit: kg, symbol Q Indicates the mass of the weight, unit: kg, symbol G c Indicates the mass of the boom, unit: kg, symbol a indicates the horizontal span of the outrigger, unit: m, symbol b indicates the longitudinal span of the outrigger, unit: m, symbol L b Indicates the length of the boom, unit: m, symbol L c Indicates the distance between the center of mass of the boom and the rotation axis, unit: m, symbol L p Indicates the distance between the center of mass of the counterweight and the axis of rotation, unit: m, symbol e d Indicates the distance between the center of gravity of the vehicle and the rotation axis, unit: m, symbol e h It represents the distance between the center of the four legs and the rotation axis, unit: m, the symbol R represents the working amplitude, unit: m, the symbol H represents the height of the weight, unit: m, the symbol α represents the rotation angle, unit: rad, and the symbol β represents the working amplitude angle, unit: rad.

[0059] The zero moment point (ZMP) refers to the point on the support surface at a certain moment where the combined force of the truck crane's gravity, external force and inertia force has no horizontal component. The zero moment point ZMP falls within the support surface, which can ensure the stability of the truck crane during movement.

[0060] Assume the mass of the main moving parts of the crane is m i , the coordinates of the centroid are (x i ,y i ,z i ), are the accelerations of the center of mass in the x, y, and z directions, respectively, and g is the acceleration due to gravity. The resultant force of gravity and inertia is:

[0061]

[0062] The moment of this resultant force about each coordinate axis is:

[0063]

[0064] Move the resultant force from the origin of the reference coordinate system to the ZMP point. The resultant moment at the ZMP point with respect to the X and Y axes is zero, so:

[0065]

[0066] get:

[0067]

[0068] Here, if the crane is stationary and only the weight is working, the ZMP equation is expressed as the formula using the gravitational acceleration g:

[0069]

[0070] This is consistent with the static moment equilibrium equation.

[0071] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An early warning method for time-varying operation of a truck crane, characterized in that: The method comprises: S1. Obtain the coordinate x of the pressure center CoP of the truck crane to be analyzed in the working state in the reference coordinate system cop ,y cop ), including: A pressure sensor is pre-installed at the end of each outrigger of the truck crane to be analyzed that contacts the ground. The pressure sensor is used to measure the pressure of the outrigger at the corresponding position on the contacted ground. The pressure at the end of each outrigger of the truck crane to be analyzed that contacts the ground is obtained based on the pressure sensor. The coordinates (x cop ,y cop ): Among them, the symbol x cop The horizontal coordinate of the center of pressure CoP is y cop represents the ordinate of the pressure center CoP, the symbol m represents the total number of outriggers of the truck crane to be analyzed, and the symbol x i Indicates the horizontal coordinate of the installation position of the i-th pressure sensor, symbol y i Indicates the ordinate of the installation position of the i-th pressure sensor, symbol P i represents the pressure value monitored by the i-th pressure sensor, where 1≤i≤m; S2, real-time monitoring to obtain the zero moment point (x zmp ,y zmp ), including: Get the mass m of the i-th component of the truck crane to be analyzed i , the centroid coordinate x of the i-th component i ,y i ,z i ), and the acceleration of the center of mass of the ith component in the x, y, and z directions Then the resultant force F of the gravity and inertia force of the truck crane to be analyzed is expressed as: Wherein, the symbol g represents the acceleration of gravity, and the moment M of the resultant force F on each coordinate axis is expressed as: Wherein, the symbol n represents the number of components of the truck crane to be analyzed. The resultant force F is moved from the origin of the reference coordinate system to the zero moment point ZMP, where the resultant moment on the X and Y axes is zero, then: get: S3, calculate the first ratio K of the truck crane to be analyzed in real time when it is in working state according to the following formula: x and the second ratio K y : Get the first ratio K x and the second ratio K y The maximum value K=max(K x ,K y ), when the maximum value K is less than or equal to the value 1, no warning is issued to the truck crane to be analyzed; when the maximum value K is greater than the value 1 and less than or equal to the predetermined threshold, a warning is issued to the truck crane to be analyzed to require low-speed operation; when the maximum value K is greater than the predetermined threshold, a warning to stop operation is issued to the truck crane to be analyzed.

2. The early warning method for time-varying operation of a truck crane according to claim 1 is characterized in that: Each of the pressure sensors in step S1 is communicatively connected to a wireless transmission module, and the wireless transmission module transmits the collected pressure data to a data receiving terminal in a wireless manner.

3. The early warning method for time-varying operation of a truck crane according to claim 1, characterized in that: The value of the predetermined threshold is between 1.1 and 1.3.

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