Stacked truck weighing gravity center calculation method

Abstract

The invention provides a stacked truck weighing gravity center calculation method, which can be used for calculating the gravity centers of two stacked trucks, that is, the gravity of the stacked trucks and the stress condition on the stacked tires can be calculated only by weighing the force on the tires in contact with the ground. According to the method, the stress of tires, making contact with the ground, of the trucks is weighed, an equation is established according to the principle that resultant force is zero in combination with the mechanical theory, and the gravity center position of the stacked trucks is obtained through analysis of an overall method and a separation method. According to the method, on the basis of the theory of theoretical mechanics, the ground stress of the stacked trucks, the stress of the stacked tires and the overall gravity center are associated, overall calculation is rapid and convenient through certain simplification and approximation, results can be easily obtained on site, and the method has the advantages of being simple in process, rapid in calculation, clear in principle and the like.

Description

Technical Field

[0001] The invention relates to a method for calculating the center of gravity of stacked trucks. Background Art

[0002] Ro-ro ship is a multi-purpose transport ship. In addition to carrying containers, it can also carry long and heavy items, grouped cargo and various vehicles. Due to the great flexibility in the variety and type of cargo loaded and unloaded, it is beneficial to increase the cargo capacity of the ship.

[0003] like Figure 1 As shown, truck stacking means that two trucks are placed on top of each other on a pallet, which greatly increases the loading density of the ship without exceeding the standard container size, effectively improving the shipping efficiency of the ship.

[0004] However, the two stacked trucks are connected only by tires and a set of connectors, and fixed to the pallet by cables. If you are not careful during loading, the center of gravity of the loading unit will shift, which will lead to dangerous situations such as cargo overturning. Furthermore, improper loading will also cause excessive force between the tires of the two stacked trucks, causing damage to the tires and the overall structure of the vehicle and creating hidden dangers.

[0005] Therefore, it is an important and necessary task to calculate the forces between stacked trucks and to calculate their center of gravity. At present, stacked truck loading and transportation is still a pioneering field, and there is no relatively complete center of gravity calculation method and theoretical derivation process. Summary of the invention

[0006] The purpose of the present invention is to provide a method for estimating the center of gravity of stacked trucks.

[0007] In order to solve the above problems, the present invention provides a method for calculating the center of gravity of stacked trucks, comprising:

[0008] Building a physical model of stacked trucks;

[0009] Perform force analysis of two stacked trucks based on the physical model of stacked trucks;

[0010] Based on the results of the force analysis, the center of gravity is calculated.

[0011] Furthermore, in the above method, a physical model of stacked trucks is established, including:

[0012] The stacked truck physical model regards two stacked trucks as two rectangular blocks of non-uniform density respectively. The two stacked trucks are connected by a pad, wherein the truck stacked at the bottom is regarded as a first rectangular block of non-uniform density, and the truck stacked at the top is regarded as a second rectangular block of non-uniform density.

[0013] Furthermore, in the above method, a force analysis of two stacked trucks is performed based on a physical model of the stacked trucks, including:

[0014] The force analysis is carried out by the overall method and the separation method, and the equation is established according to the principle that the resultant moment is zero; the value of the corresponding variable is calculated based on the equation.

[0015] Furthermore, in the above method, the overall method comprises:

[0016] The stacked trucks are considered as a whole for force analysis, without considering the internal forces between the upper truck and the lower truck, including the friction and support force between them, in order to obtain the mass of the truck.

[0017] Furthermore, in the above method, the stacked trucks are considered as a whole for force analysis, and the internal forces between the upper truck and the lower truck, including the friction and support force between them, are not considered, so as to obtain the mass of the trucks, including:

[0018] Define a as the distance from the front end of the vehicle to the center of gravity, b as the distance from the center of gravity to the first rear wheel, and l as the length of the vehicle, where the distance between the front and rear wheels and the length of the vehicle are known, and only a is unknown; N 1 is the support force of the front wheel of the upper truck; N 2 The first supporting force of the upper truck rear wheel; N 3 The second supporting force of the upper truck rear wheel; N 4 The second supporting force for the rear wheels of the truck below; N 5 The first supporting force of the rear wheel of the truck below; N 6 is the support force of the front wheel of the truck below; f 1 is the horizontal friction force of the front wheel of the upper truck; f 2 is the first horizontal friction force of the upper truck rear wheel; f 3 is the second horizontal friction force of the upper truck rear wheel; f 4 is the second horizontal friction force of the rear wheel of the truck below; f 5 is the first horizontal friction force of the rear wheel of the truck below; f 6 is the horizontal friction force of the front wheels of the truck below;

[0019] f 1 ′ is the balanced friction force of the front wheel of the truck above in the opposite direction; f 2 ′ is the first equilibrium friction force of the upper truck rear wheel in the same direction and in the opposite direction; f 3 ′ is the second equilibrium friction force of the rear wheel of the truck above with equal magnitude and opposite direction; f 4 ′ is the second equilibrium friction force of the rear wheel of the truck below in the opposite direction; f 5 ′ is the first equilibrium friction force of the rear wheel of the truck below in the opposite direction; f 6 ' is the balanced friction force of the front wheel of the truck below in the opposite direction; N1 ' is the pressure in the opposite direction of the front wheel of the truck above; N 2 ' is the first pressure of the upper truck rear wheel in the opposite direction; N 3 ' is the second pressure in the opposite direction of the rear wheel of the truck above; N 4 ' is the second pressure in the opposite direction of the rear wheel of the truck below; N 5 ' is the first pressure of the rear wheel of the truck below in the opposite direction; N 6 ' is the pressure of the truck below in the opposite direction;

[0020] In the overall analysis, the following equilibrium equations are listed based on the vertical and horizontal force balance and the moment balance calculation for the lower left corner:

[0021] N 1 +N 4 +N 5 +N 6 =G 1 +G 2 =2G (1)

[0022] T 1 +f 1 +f 4 =T 6 +f 5 +f 6 (2)

[0023] Gacosα+G(l-a+(a+b)cosα)=N 4 (a+b)cosα+N 5 (l-a+(a+b)cosα) (3)

[0024] Among them, α is the angle formed by the upper truck when stacked with the horizontal plane, which is a known quantity measured;

[0025] According to formula (1), by weighing the forces on the tires of the two stacked trucks, the overall gravity G of the stacked trucks is obtained, and according to the friction formula:

[0026] f static ≈f sliding =μN

[0027] The friction forces f in equation (2) are 1 to f 6 , calculated from the friction coefficient μ of the tire and the supporting force N;

[0028] According to formula (3), the distance a from the front end of the vehicle to the center of gravity is calculated;

[0029] Therefore, the unknown variable is T 1 ,T 6 .

[0030] Furthermore, in the above method, the separation method includes: analyzing the stress states of the upper truck and the lower truck separately to obtain the interaction force between the two vehicles, including: the pressure between the tires of the two vehicles.

[0031] Furthermore, in the above method, the separation method includes: analyzing the force states of the upper truck and the lower truck separately to obtain the interaction force between the two trucks, including:

[0032] For the force analysis of the truck above, the following equilibrium equations are listed based on the vertical and horizontal force balance, as well as the moment balance calculation for the lower left corner:

[0033] N 1 +N 2 +N 3 =G (4)

[0034] T 1 +f 1 +f 2 =f 3 (5)

[0035] Gacosα+f 2 (a+b)sinα=[N 2 (a+b)+N 3 l]cosα+f 3 (a+b)sinα (6)

[0036] Among them, the unknown variable is N 2 ,N 3 ,T 1 ;

[0037] For the force analysis of the truck below, the following equilibrium equations are listed based on the vertical and horizontal force balance, as well as the moment balance calculation for the lower left corner:

[0038]

[0039] The height difference between the upper and lower surfaces of the truck model is ignored when calculating the moment, so for f 2 ′ and f 3 ′ is not included in the calculation of torque; For equations (7) and (8) in the above formula, they are related to the previous equations and are redundant, so they are deleted; in the remaining equations, the unknown variable is N 3 ′;

[0040] Therefore, based on the above analysis, the following equations are obtained:

[0041]

[0042] Among them, the unknown variable is T 1 ,T 6 ,N 2 ,N 3 ;

[0043] The system of equations is transformed into the form of Ax=b, where

[0044]

[0045]

[0046] By solving the above formula, we can get:

[0047]

[0048] in:

[0049]

[0050]

[0051]

[0052] Furthermore, in the above method, based on the result of the force analysis, the center of gravity is estimated, including:

[0053] Based on the calculated values ​​of the variables, and according to the lever principle that the resultant moment is zero, the centers of gravity of the two trucks are combined.

[0054] Furthermore, in the above method, based on the calculated values ​​of the variables and according to the lever principle that the resultant moment is zero, the centers of gravity of the two trucks are synthesized, including:

[0055] The overall center of gravity of the two trucks The overall center of gravity is the midpoint of the line connecting the center of gravity of the upper truck and the lower truck. The distance from the leftmost side of the front of the truck above is:

[0056]

[0057] Compared with the prior art, the method for calculating the center of gravity of stacked trucks of the present invention includes a physical model of the stacked trucks, force analysis and center of gravity calculation.

[0058] The method for calculating the center of gravity of stacked trucks designed in the present invention can be mainly used to calculate the center of gravity of two stacked trucks. That is, the gravity of the stacked trucks and the force on the stacked tires can be calculated simply by weighing the force on the tires in contact with the ground, thereby providing a reference for the operations of loading and unloading workers.

[0059] The method for calculating the center of gravity of a stacked truck of the present invention mainly measures the force on the tire of the truck in contact with the ground, and combines the theory of theoretical mechanics to establish an equation based on the principle that the resultant force (torque) is zero, and obtains the center of gravity position of the stacked truck through the overall method and the separation method. Partial simplification and approximation are used in the process of calculating the center of gravity, so as to facilitate the on-site staff to quickly calculate the center of gravity position and tire pressure, provide a reference for the operation, and be suitable for on-site quick calculation.

[0060] The patent of this invention is based on the theory of theoretical mechanics. It establishes a connection between the ground force of stacked trucks and the force of stacked tires and the overall center of gravity. Through certain simplifications and approximations, the overall calculation is fast and convenient, and the results are easy to obtain on-site. It has the advantages of simple process, fast calculation, and clear principles.

[0061] The present invention takes into account the actual stress conditions of stacked trucks and, in combination with existing engineering practices, proposes a method for estimating the center of gravity based on measuring the force on the tires of the trucks contacting the ground. On the basis of existing theories, a calculation method with simple process, fast calculation and clear principle is established.

[0062] The present invention provides a reference and help for on-site construction workers to quickly calculate the center of gravity of the truck and the interaction force between tires. Based on the existing theoretical mechanics basic theory and combined with the current engineering experience of truck stacking transportation, the patent of this invention derives the calculation formula of the center of gravity of the stacked truck and the calculation formula of the pressure between the rear wheels of the trucks that are in contact with each other, and makes certain simplifications and approximations to the stacked truck model to facilitate derivation and understanding. In the derivation process, the various parameters and variables involved are elaborated in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 is a physical schematic diagram of truck stacking according to an embodiment of the present invention;

[0064] Figure 2 is a schematic diagram of a physical model of truck stacking according to an embodiment of the present invention;

[0065] Figure 3 This is a schematic diagram of the forces acting on a single truck according to an embodiment of the present invention;

[0066] Figure 4 This is a schematic diagram of the forces acting on two trucks according to an embodiment of the present invention;

[0067] Figure 5 It is a schematic diagram of force analysis of an upper truck according to an embodiment of the present invention;

[0068] Figure 6 It is a schematic diagram of force analysis of a truck below according to an embodiment of the present invention;

[0069] Figure 7Schematic diagram of the center of gravity of a stacking truck according to an embodiment of the present invention. DETAILED DESCRIPTION

[0070] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0071] like Figures 2 to 7 As shown, the present invention provides a method for calculating the center of gravity of stacked trucks, comprising:

[0072] Step S1, establishing a physical model of stacked trucks;

[0073] Step S2, performing a force analysis of two stacked trucks based on a physical model of the stacked trucks;

[0074] Step S3, based on the result of the force analysis, the center of gravity is calculated.

[0075] Here, the method for calculating the center of gravity of a stacked truck of the present invention includes a physical model of the stacked truck, a force analysis, and a center of gravity calculation.

[0076] The method for calculating the center of gravity of stacked trucks designed in the present invention can be mainly used to calculate the center of gravity of two stacked trucks. That is, the gravity of the stacked trucks and the force on the stacked tires can be calculated simply by weighing the force on the tires in contact with the ground, thereby providing a reference for the operations of loading and unloading workers.

[0077] In one embodiment of the method for calculating the center of gravity of stacked trucks according to the present invention, step S1, establishing a physical model of the stacked trucks, comprises:

[0078] like Figure 1 As shown, the physical model of stacked trucks regards two stacked trucks as two rectangular blocks of non-uniform density respectively. The two stacked trucks are connected by a pad, wherein the truck stacked at the bottom is regarded as a first rectangular block of non-uniform density, and the truck stacked at the top is regarded as a second rectangular block of non-uniform density.

[0079] Here, first, the two stacked trucks are regarded as rectangular blocks with non-uniform density, mainly because the mass density of the front part of the truck is higher along the length direction. If the whole vehicle is only regarded as a rectangular block (the center of gravity is located in the middle of the rectangular block), it does not conform to physical reality, so this treatment should be done when simplifying it. Secondly, each truck can be regarded as a rectangular block, and the problem can be simplified to a plane problem for solution. This is considered from the symmetry of the truck and the force, because the tires and mass distribution of the trucks are basically consistent along the width direction. Finally, when the two trucks are stacked, an angle will be generated. If there is only one fulcrum, and the pressure and friction are transmitted at the tires that contact each other here, the bending moment at the end of the vehicle is large, which not only poses a safety hazard, but also does not conform to actual operation. Therefore, when simplifying the model, a pad should be added. This pad can transmit support force and friction, regardless of weight.

[0080] The physical model of stacked trucks can be simplified as Figure 2 shown.

[0081] The two large rectangles are a simplified model of a truck. A small square between the two large rectangles is a small pad, which is used to transmit support force and friction force in the calculation, and its weight is ignored.

[0082] In one embodiment of the method for calculating the center of gravity of stacked trucks according to the present invention, step S2, performing a force analysis of two stacked trucks based on a physical model of the stacked trucks, includes:

[0083] The force analysis is carried out by the overall method and the separation method, and the equation is established based on the principle that the resultant force (torque) is zero; the value of the corresponding variable is calculated based on the equation.

[0084] In one embodiment of the method for calculating the center of gravity of stacked trucks according to the present invention, the overall method includes:

[0085] The stacked trucks are considered as a whole for force analysis. At this time, there is no need to consider the internal forces between the upper truck and the lower truck, including: mutual friction, support force, etc., so as to quickly obtain the mass of the truck.

[0086] A parked truck has six tires in contact with the ground, and they are symmetrical. Therefore, the tires at the same position can be simplified to one force. The entire truck is subject to gravity and three supporting forces, such as Figure 3 shown.

[0087] In one embodiment of the method for calculating the center of gravity of stacked trucks of the present invention, the stacked trucks are regarded as a whole for force analysis. At this time, there is no need to consider the internal forces between the upper truck and the lower truck, including: mutual friction, support force, etc., so as to quickly obtain the mass of the truck, including:

[0088] Define a as the distance from the front end of the vehicle to the center of gravity, b as the distance from the center of gravity to the first rear wheel, and l as the length of the vehicle. The distance between the front and rear wheels and the length of the vehicle are both known, so only a is unknown; N 1 is the support force of the front wheel of the upper truck; N 2 The first supporting force of the upper truck rear wheel; N 3 The second supporting force of the upper truck rear wheel; N 4 The second supporting force for the rear wheels of the truck below; N 5 The first supporting force of the rear wheel of the truck below; N 6 is the support force of the front wheel of the truck below; f 1 is the horizontal friction force of the front wheel of the upper truck; f 2 is the first horizontal friction force of the upper truck rear wheel; f 3 is the second horizontal friction force of the upper truck rear wheel; f 4 is the second horizontal friction force of the rear wheel of the truck below; f 5 is the first horizontal friction force of the rear wheel of the truck below; f 6 is the horizontal friction force of the front wheels of the truck below;

[0089] f 1 ′ is the balanced friction force of the front wheel of the truck above in the opposite direction; f 2 ′ is the first equilibrium friction force of the upper truck rear wheel in the same direction and in the opposite direction; f 3 ′ is the second equilibrium friction force of the rear wheel of the truck above with equal magnitude and opposite direction; f 4 ′ is the second equilibrium friction force of the rear wheel of the truck below in the opposite direction; f 5 ′ is the first equilibrium friction force of the rear wheel of the truck below in the opposite direction; f 6 ' is the balanced friction force of the front wheel of the truck below in the opposite direction; N 1 ' is the pressure in the opposite direction of the front wheel of the truck above; N 2 ' is the first pressure of the upper truck rear wheel in the opposite direction; N 3 ' is the second pressure in the opposite direction of the rear wheel of the truck above; N 4 ' is the second pressure in the opposite direction of the rear wheel of the truck below; N 5 ' is the first pressure of the rear wheel of the truck below in the opposite direction; N 6 ' is the pressure of the truck below in the opposite direction;

[0090] like Figure 4 As shown in Figure 2, in the overall analysis, the direct mutual pressure and support force (including the friction force generated) of the two trucks belong to internal forces, so Figure 4 Not marked or marked as light color; In addition, f 4 and f 5 The direction of is related to the actual force, and the direction marked on the figure is the positive direction; T 1 With T6 The external pulling force on the truck is actually the pulling force provided by the ropes and straps used to fix the truck.

[0091] According to the vertical and horizontal force balance, and the moment balance calculation for the lower left corner, the following equilibrium equation can be listed:

[0092] N 1 +N 4 +N 5 +N 6 =G 1 +G 2 =2G (1)

[0093] T 1 +f 1 +f 4 =T 6 +f 5 +f 6 (2)

[0094] Gacosα+G(l-a+(a+b)cosα)=N 4 (a+b)cosα+N 5 (l-a+(a+b)cosα) (3)

[0095] Among them, α is the angle formed by the stacked trucks above and the horizontal plane, which is a known quantity that can be measured;

[0096] According to formula (1), the overall gravity G of the stacked trucks can be obtained by weighing the forces on the tires of the two stacked trucks, and according to the friction formula:

[0097] f static ≈f sliding =μN

[0098] The friction forces f in equation (2) are 1 to f 6 Calculated from the friction coefficient μ of the tire and the supporting force N;

[0099] According to formula (3), the distance a from the front end of the vehicle to the center of gravity can be calculated.

[0100] Therefore, the unknown variable is T 1 ,T 6 .

[0101] In one embodiment of the method for calculating the center of gravity of stacked trucks of the present invention, the separation method, also called the isolation method, includes: separately analyzing the stress states of the upper truck and the lower truck to obtain the interaction force between the two vehicles, including the extremely important pressure between the tires of the two vehicles.

[0102] In one embodiment of the method for calculating the center of gravity of stacked trucks of the present invention, the interaction force between the two trucks is obtained by analyzing the force states of the upper truck and the lower truck separately, including the extremely important pressure between the tires of the two trucks, including:

[0103] like Figure 5 As shown, for the force analysis of the truck above, the following equilibrium equations are listed based on the vertical and horizontal force balances and the moment balance calculation for the lower left corner:

[0104] N 1 +N 2 +N 3 =G (4)

[0105] T 1 +f 1 +f 2 =f 3 (5)

[0106] Gacosα+f 2 (a+b)sinα=[N 2 (a+b)+N 3 l]cosα+f 3 (a+b)sinα (6)

[0107] Among them, the unknown variable is N 2 ,N 3 ,T 1 ;

[0108] like Figure 6 As shown, for the force analysis of the truck below, the following equilibrium equation can be listed based on the vertical and horizontal force balance, as well as the moment balance calculation for the lower left corner:

[0109]

[0110] The height difference between the upper and lower surfaces of the truck model is ignored when calculating the moment, so for f 2 ′ and f 3 ′ is not included in the calculation of torque; for equations (7) and (8) in the above formula, they are related to the previous equations and are redundant, so they can be deleted; in the remaining equations, the unknown variable is N 3 ′.

[0111] Therefore, based on the above analysis, we can get the following equations:

[0112]

[0113] Among them, the unknown variable is T 1 ,T 6 ,N 2,N 3 , the problem is completely solvable.

[0114] The above equations can be transformed into the form of Ax = b, where

[0115]

[0116]

[0117] By solving the above formula, we can get:

[0118]

[0119] in:

[0120]

[0121]

[0122]

[0123] In one embodiment of the method for calculating the center of gravity of stacked trucks according to the present invention, step S3, calculating the center of gravity based on the result of the force analysis, comprises:

[0124] Based on the calculated values ​​of the variables, and according to the lever principle that the resultant moment is zero, the centers of gravity of the two trucks are combined.

[0125] In one embodiment of the method for calculating the center of gravity of stacked trucks of the present invention, based on the values ​​of the calculated variables and according to the lever principle of zero resultant moment, the centers of gravity of the two trucks are synthesized, including:

[0126] According to the principle of center of gravity synthesis, since the weight of the upper truck and the lower truck is the same, the overall center of gravity is the midpoint of the line connecting the two trucks, such as Figure 7 shown.

[0127] Overall center of gravity The overall center of gravity is the midpoint of the line connecting the center of gravity of the upper truck and the lower truck. The distance from the leftmost side of the front of the truck above is:

[0128] l G％ =bcosα+(la).

[0129] By adopting the above scheme, the method for estimating the center of gravity of stacked trucks proposed in the present invention has the following characteristics:

[0130] Simply weigh the tires of the stacked trucks and substitute them into the formula derived above to get the final center of gravity position. The derivation process is clear and the calculation is simple.

[0131] Through the obtained calculation formula, the pressure N between tires can be quickly obtained. 2 ,N 3 , which is convenient for on-site construction personnel to monitor tire pressure in real time.

[0132] The content of the derivation of the center of gravity and force calculation of the stacked trucks is complete, the force analysis model is reasonable, the process is shown in the figure, and the logic is clear.

[0133] The method for calculating the center of gravity of a stacked truck of the present invention mainly measures the force on the tire of the truck in contact with the ground, and combines the theory of theoretical mechanics to establish an equation based on the principle that the resultant force (torque) is zero, and obtains the center of gravity position of the stacked truck through the overall method and the separation method. Partial simplification and approximation are used in the process of calculating the center of gravity, so as to facilitate the on-site staff to quickly calculate the center of gravity position and tire pressure, provide a reference for the operation, and be suitable for on-site quick calculation.

[0134] The patent of this invention is based on the theory of theoretical mechanics. It establishes a connection between the ground force of stacked trucks and the force of stacked tires and the overall center of gravity. Through certain simplifications and approximations, the overall calculation is fast and convenient, and the results are easy to obtain on-site. It has the advantages of simple process, fast calculation, and clear principles.

[0135] The present invention takes into account the actual stress conditions of stacked trucks and, in combination with existing engineering practices, proposes a method for estimating the center of gravity based on measuring the force on the tires of the trucks contacting the ground. On the basis of existing theories, a calculation method with simple process, fast calculation and clear principle is established.

[0136] The present invention provides a reference and help for on-site construction workers to quickly calculate the center of gravity of the truck and the interaction force between tires. Based on the existing theoretical mechanics basic theory and combined with the current engineering experience of truck stacking transportation, the patent of this invention derives the calculation formula of the center of gravity of the stacked truck and the calculation formula of the pressure between the rear wheels of the trucks that are in contact with each other, and makes certain simplifications and approximations to the stacked truck model to facilitate derivation and understanding. In the derivation process, the various parameters and variables involved are elaborated in detail.

[0137] The present invention can establish a physical model of the stacked trucks according to the problem background and beneficial simplification, and according to the relevant theoretical formulas of theoretical mechanics, by performing force analysis on the model, the force conditions in the model are deduced, and finally according to the obtained calculation results, the center of gravity position of the stacked trucks can be simply obtained, which provides a reference for on-site construction personnel and can be used as a basis for timely adjustment of specific operations.

[0138] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0139] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0140] Obviously, those skilled in the art can make various changes and modifications to the invention without departing from the spirit and scope of the invention. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A method for calculating the center of gravity of stacked trucks. It is characterized in that include: Building a physical model of stacked trucks; Perform force analysis of two stacked trucks based on the physical model of stacked trucks; Based on the results of the force analysis, the center of gravity is calculated.

2. The method for calculating the center of gravity of stacked trucks as claimed in claim 1, It is characterized in that Physical model of stacked trucks, including: The stacked truck physical model regards two stacked trucks as two rectangular blocks of non-uniform density respectively. The two stacked trucks are connected by a pad, wherein the truck stacked at the bottom is regarded as a first rectangular block of non-uniform density, and the truck stacked at the top is regarded as a second rectangular block of non-uniform density.

3. The method for calculating the center of gravity of stacked trucks as claimed in claim 1, It is characterized in that The force analysis of two stacked trucks is performed based on the physical model of the stacked trucks, including: The force analysis is carried out by the overall method and the separation method, and the equation is established according to the principle that the resultant moment is zero; the value of the corresponding variable is calculated based on the equation.

4. The method for calculating the center of gravity of stacked trucks as claimed in claim 1, It is characterized in that The holistic approach includes: The stacked trucks are considered as a whole for force analysis, without considering the internal forces between the upper truck and the lower truck, including the friction and support force between them, in order to obtain the mass of the truck.

5. The method for calculating the center of gravity of stacked trucks as claimed in claim 4, It is characterized in that The stacked trucks are considered as a whole for force analysis, ignoring the internal forces between the upper truck and the lower truck, including the friction and support between them, to obtain the mass of the trucks, including: Define a as the distance from the front end of the vehicle to the center of gravity, b as the distance from the center of gravity to the first rear wheel, and l as the length of the vehicle, where the distance between the front and rear wheels and the length of the vehicle are known, and only a is unknown; N is the support force of the front wheel of the upper truck; N 2 The first supporting force of the upper truck rear wheel; N 3 The second supporting force of the upper truck rear wheel; N 4 The second supporting force for the rear wheels of the truck below; N 5 The first supporting force of the rear wheel of the truck below; N 6 is the support force of the front wheel of the truck below; f 1 is the horizontal friction force of the front wheel of the upper truck; f 2 is the first horizontal friction force of the upper truck rear wheel; f 3 is the second horizontal friction force of the upper truck rear wheel; f 4 is the second horizontal friction force of the rear wheel of the truck below; f 4 is the first horizontal friction force of the rear wheel of the truck below; f 6 is the horizontal friction force of the front wheels of the truck below; f 1 ′ is the balanced friction force of the front wheel of the truck above in the opposite direction; f 2 ′ is the first equilibrium friction force of the upper truck rear wheel in the same direction and in the opposite direction; f 3 ′ is the second equilibrium friction force of the rear wheel of the truck above with equal magnitude and opposite direction; f 4 ′ is the second equilibrium friction force of the rear wheel of the truck below in the opposite direction; f 5 ′ is the first equilibrium friction force of the rear wheel of the truck below in the opposite direction; f 6 ' is the balanced friction force of the front wheel of the truck below in the opposite direction; N 1 ' is the pressure in the opposite direction of the front wheel of the truck above; N 2 ' is the first pressure of the upper truck rear wheel in the opposite direction; N 3 ' is the second pressure in the opposite direction of the rear wheel of the truck above; N 4 ' is the second pressure in the opposite direction of the rear wheel of the truck below; N 5 ' is the first pressure of the rear wheel of the truck below in the opposite direction; N 6 ' is the pressure of the truck below in the opposite direction; In the overall analysis, the following equilibrium equations are listed based on the vertical and horizontal force balance and the moment balance calculation for the lower left corner: N 1 +N 4 +N 5 +N 6 =G 1 +G 2 =2G (1) T 1 +f 1 +f 4 =T 6 +f 5 +f 6 (2) Gacosα+G(l-a+(a+b)cosα)=N 4 (a+b)cosα+N 5 (l-a+(a+b)cosα) (3) Among them, α is the angle formed by the upper truck when stacked with the horizontal plane, which is a known quantity measured; According to formula (1), by weighing the forces on the tires of the two stacked trucks, the overall gravity G of the stacked trucks is obtained, and according to the friction formula: f static ≈f sliding =μN The friction forces f in equation (2) are 1 to f 6 , calculated from the friction coefficient μ of the tire and the supporting force N; According to formula (3), the distance a from the front end of the vehicle to the center of gravity is calculated; Therefore, the unknown variable is T 1 ,T 6 .

6. The method for calculating the center of gravity of stacked trucks as claimed in claim 5, It is characterized in that The separation method includes: analyzing the stress states of the upper truck and the lower truck separately to obtain the interaction force between the two vehicles, including: the pressure between the tires of the two vehicles.

7. The method for calculating the center of gravity of stacked trucks as claimed in claim 6, It is characterized in that The separation method includes: analyzing the force states of the upper truck and the lower truck separately to obtain the interaction force between the two trucks, including: For the force analysis of the truck above, the following equilibrium equations are listed based on the vertical and horizontal force balance, as well as the moment balance calculation for the lower left corner: N 1 +N 2 +N 3 =G (4) T 1 +f 1 +f 2 =f 3 (5) Gacosα+f 2 (a+b)sinα=[N 2 (a+b)+N 3 l]cosα+f 3 (a+b)sinα (6) Among them, the unknown variable is N 2 ,N 3 ,T 1 ; For the force analysis of the truck below, the following equilibrium equations are listed based on the vertical and horizontal force balance, as well as the moment balance calculation for the lower left corner: The height difference between the upper and lower surfaces of the truck model is ignored when calculating the moment, so for f 2 ′ and f 3 ′ is not included in the calculation of torque; For equations (7) and (8) in the above formula, they are related to the previous equations and are redundant, so they are deleted; in the remaining equations, the unknown variable is N 3 ′; Therefore, based on the above analysis, the following equations are obtained: Among them, the unknown variable is T 1 ,T 6 ,N 2 ,N 3 ; The system of equations is transformed into the form of Ax=b, where By solving the above formula, we can get: in:

8. The method for calculating the center of gravity of stacked trucks as claimed in claim 7, It is characterized in that Based on the results of the force analysis, the center of gravity is calculated, including: Based on the calculated values ​​of the variables and according to the lever principle that the resultant moment is zero, the centers of gravity of the two trucks are combined.

9. The method for calculating the center of gravity of stacked trucks as claimed in claim 8, It is characterized in that Based on the calculated values ​​of the variables and according to the lever principle that the resultant moment is zero, the centers of gravity of the two trucks are combined, including: The overall center of gravity of the two trucks The overall center of gravity is the midpoint of the line connecting the center of gravity of the upper truck and the lower truck. The distance from the leftmost side of the front of the truck above is: l G％ =bcosα+(l-a)。

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