Hinge point optimization method and optimization system for bulk material system dumping mechanism

Abstract

The present application discloses a hinge optimization method and an optimization system for a bulk material system dumping mechanism, and relates to the field of engineering optimization design. It includes: obtaining the angle time history curve and force time history curve of the cylinder during the tipping process of the dumping mechanism by means of multi-body dynamics-discrete element coupling modeling according to the initial hinge information; determining the angle-torque time history curve between the tipping angle of the dumping mechanism and the applied torque of the cylinder according to the angle time history curve and the force time history curve; optimizing and changing the hinge position of the cylinder on the dumping mechanism based on the angle-torque time history curve and the constraint conditions of the cylinder to determine the maximum applied force of the cylinder at different hinge positions; determining the hinge position with the minimum maximum applied force as the target hinge position. The present invention adopts the "multi-body dynamics + discrete element" coupling model, which can truly reflect the change of the cylinder force of the dumping mechanism during the dumping process, proposes an equivalent optimization mathematical model, and realizes the optimization of the hinge group with minimized cylinder force.

Description

Technical Field

[0001] The present application relates to the field of engineering optimization design, and in particular to a hinge point optimization method and optimization system for a bulk material system dumping mechanism. Background Art

[0002] The dumping mechanism including the ear box is a temporary harvesting silo of agricultural plant (such as corn) harvesters, which is used to temporarily store the harvested ears. When the ear box is full, the cylinder is extended and retracted to drive the box body to flip, so that the harvested ears are quickly transferred to the truck hopper and transported to the designated granary. Among them, the position relationship of the hinge point of the ear box determines the force of each mechanism during the flipping process. Therefore, a reasonable hinge point arrangement can achieve the optimal matching of the cylinder force and the cylinder stroke, that is, under the premise of meeting the safety of the cylinder design, the maximum cylinder force during the flipping process can be minimized, and a small-sized cylinder can be used accordingly, thereby reducing the design cost.

[0003] The existing technology for variable amplitude motion usually takes minimizing the oil cylinder force as the optimization goal to achieve the optimization of the hinge position. However, the existing technology is only applicable to the variable amplitude motion of a rigid body (the center of gravity position can be considered relatively unchanged), and the corn ear pile belongs to a bulk material system. In other words, when the silo where the corn ear pile is located flips, the shape of the corn ear pile in the silo will also change accordingly. The change in the center of gravity of the corn ear pile in the silo will cause the change in the oil cylinder force to be different from the conventional rigid body motion, so it cannot be accurately simulated.

[0004] It can be seen that the existing technology cannot take into account the change of the center of gravity of the discrete materials as the position changes, which leads to inaccurate theoretical calculation of the cylinder force. Especially during the unloading process of the fruit ears, the fruit ears in the bin decrease, and the cylinder force also decreases accordingly, so the calculation of the cylinder force is inconsistent with the actual situation, which affects the subsequent selection of cylinder specifications and optimization of hinge points. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a hinge point optimization method and optimization system for a bulk material system dumping mechanism, so as to achieve hinge point optimization for minimizing the cylinder force during the dumping process of a box bulk material system.

[0006] In order to achieve the above-mentioned objectives, the first aspect of the present application provides a hinge point optimization method for a bulk material system dumping mechanism, the hinge point optimization method comprising: according to the initial hinge point information of the cylinder on the dumping mechanism, obtaining the angle time history curve and force time history curve of the cylinder during the flipping process of the dumping mechanism by means of multi-body dynamics-discrete element coupling modeling, wherein the initial hinge point information includes the initial position information of at least two fixed hinge points and at least one mobile hinge point; according to the angle time history curve and the force time history curve, determining the angle-torque time history curve between the flipping angle of the dumping mechanism and the applied torque of the cylinder; based on the angle-torque time history curve and the constraint conditions of the cylinder, optimizing the hinge point position of the cylinder on the dumping mechanism to determine the maximum applied force of the cylinder at different hinge point positions; and determining the hinge point position with the smallest maximum applied force as the target hinge point position.

[0007] In an embodiment of the present application, the angle time history curve and force time history curve of the cylinder during the flipping process of the dumping mechanism are obtained by a multi-body dynamics-discrete element coupling modeling method based on the initial hinge information of the cylinder on the dumping mechanism, including: establishing a multi-body dynamics model based on the connection relationship between the dumping mechanism, the hinge and the cylinder, wherein the connection relationship includes the rotational connection relationship between the dumping mechanism and the hinge, and the sliding connection relationship between the cylinder and the hinge; establishing a discrete element model based on discrete material parameters in the dumping mechanism, wherein the discrete material parameters include the mass of discrete materials, the shape of discrete material piles, the first contact parameters between discrete materials, and the second contact parameters between discrete materials and the wall of the box; determining the angle time history curve of the cylinder during the flipping process of the dumping mechanism based on the pushing speed of the cylinder and the multi-body dynamics model, wherein the pushing speed is less than the set speed; and coupling the discrete element model with the multi-body dynamics model to determine the force time history curve of the cylinder during the flipping process of the dumping mechanism.

[0008] In the embodiment of the present application, the initial hinge point information includes a first fixed hinge point, a second fixed hinge point and a mobile hinge point, and the angle time history curve of the cylinder during the flipping process of the dumping mechanism is determined based on the pushing speed of the cylinder and the multi-body dynamics model, including: based on the pushing speed v, the angle time history curve θ(t) of the set angle with the pushing time t is determined by the following formula:

[0009] Lc(t)=Lc1+v*t

[0010]

[0011] Among them, Lc1 is the length of the cylinder in the initial state, Lc(t) is the length of the cylinder during the driving process; La0 is the initial distance of the line segment AB formed by the first fixed hinge point A and the second fixed hinge point B, Lb0 is the initial distance of the line segment AC formed by the first fixed hinge point A and the movable hinge point C; the set angle is the angle formed with the first fixed hinge point A as the vertex and the line segment AC and the line segment AB as the sides, and k0 is the initial angle of the set angle.

[0012] In the embodiment of the present application, determining the angle-torque time-history curve between the flipping angle of the dumping mechanism and the applied torque of the cylinder according to the angle-time-history curve and the force-time-history curve includes: determining the angle-torque time-history curve M(t) according to the following formula based on the angle-time-history curve θ(t) and the force-time-history curve F(t):

[0013]

[0014] M(t)=F(t)*l(t)

[0015] Wherein, l(t) is the time history curve of the force arm of the oil cylinder on the dumping mechanism at the initial hinge position.

[0016] In an embodiment of the present application, the hinge position of the cylinder on the dumping mechanism is optimized and changed based on the angle-torque time-history curve and the constraint conditions of the cylinder to determine the maximum applied force of the cylinder at different hinge positions, including: changing the position of the second fixed hinge and the mobile hinge to determine a first distance between the first fixed hinge and the second fixed hinge, and a second distance between the first fixed hinge and the mobile hinge; determining a force arm time-history curve of the cylinder on the dumping mechanism under the optimized changed hinge position based on the first distance and the second distance; and determining the maximum applied force of the cylinder at the hinge position based on the force arm time-history curve and the angle-torque time-history curve.

[0017] In the embodiment of the present application, the determining of the arm time history curve of the oil cylinder to the dumping mechanism under the optimized changed hinge position according to the first distance and the second distance includes: determining the arm time history curve D of the oil cylinder to the dumping mechanism under the optimized changed hinge position according to the first distance La and the second distance Lb by the following formula: CYL (t):

[0018]

[0019] Among them, the position information of the first fixed hinge point is the origin (0,0), the changed position information of the second fixed hinge point is (X1,Y1), and the changed position information of the movable hinge point is (X2,Y2); k is the initial angle of the set angle at the initial hinge point position at the hinge point position, and θ(t) is the angle time curve of the set angle at the initial hinge point position.

[0020] In the embodiment of the present application, the determining of the maximum applied force of the oil cylinder at the hinge position according to the arm time history curve and the angle torque time history curve includes: determining the maximum applied force of the oil cylinder at the hinge position according to the arm time history curve D CYL (t) and the angle-torque time history curve M(t), the following formula is used to determine the maximum applied force F of the cylinder at the hinge position. CYL_MAX :

[0021]

[0022] F CYL_MAX =MAX{F CYL (t)}.

[0023] In the embodiment of the present application, the constraint conditions include a stability coefficient and a minimum installation distance limit of the oil cylinder.

[0024] In an embodiment of the present application, the hinge position of the oil cylinder on the dumping mechanism is optimized and changed by at least one of the following algorithms: genetic algorithm, downhill method, annealing method.

[0025] According to a second aspect of the present application, there is provided a hinge point optimization system for a bulk material system dumping mechanism, the optimization system comprising: a time-history curve acquisition device for acquiring an angle time-history curve and a force time-history curve of the cylinder during the flipping process of the dumping mechanism in a multi-body dynamics-discrete element coupling modeling manner according to initial hinge point information of the cylinder on the dumping mechanism, wherein the initial hinge point information comprises initial position information of at least two fixed hinge points and at least one mobile hinge point; an angle-torque determination device for determining an angle-torque time-history curve between the flipping angle of the dumping mechanism and the applied torque of the cylinder according to the angle-torque time-history curve and the force-torque time-history curve; a hinge point optimization change device for optimizing and changing the hinge point position of the cylinder on the dumping mechanism based on the angle-torque time-history curve and the constraint conditions of the cylinder to determine the maximum applied force of the cylinder at different hinge point positions; and a target hinge point determination device for determining the hinge point position with the smallest maximum applied force as the target hinge point position.

[0026] Through the above technical solution, the coupling model of "multi-body dynamics + discrete element" adopted by the present invention realizes the extraction of the pushing cylinder force of the box containing discrete materials during the flipping operation, which can truly reflect the change of the cylinder force of the dumping mechanism during the dumping process, and thus obtain the total bending moment value applied by the dumping mechanism and the discrete materials therein. Based on the bending moment dynamic curve calculated by the cylinder force and combined with the geometric flipping curve of the dumping mechanism, an equivalent optimization mathematical model of the dumping mechanism is proposed, which provides feasibility for the subsequent optimization of the hinge group to minimize the cylinder force.

[0027] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0029] Figure 1 A schematic diagram of a process flow of a hinge point optimization method for a bulk material system dumping mechanism according to an embodiment of the present application is schematically shown;

[0030] Figure 2 A schematic diagram schematically shows a coupling model calculation process according to an embodiment of the present application;

[0031] Figure 3 A schematic diagram showing the change of the hinge point position during the flipping process of the box according to an embodiment of the present application is shown;

[0032] Figure 4 A schematic diagram schematically shows an optimization model analysis process according to an embodiment of the present application;

[0033] Figure 5 A schematic diagram showing the change of the hinge point position during the flipping process of the box according to an embodiment of the present application is shown;

[0034] Figure 6 A schematic diagram schematically shows a hinge point position constraint range according to an embodiment of the present application;

[0035] Figure 7 The structural diagram of a hinge point optimization system of a bulk material system dumping mechanism according to an embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0037] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application are in compliance with the relevant provisions of national laws and regulations. In the embodiments of this application, some existing solutions in the industry such as certain software, components, and models may be mentioned, which should be considered as exemplary. Their purpose is only to illustrate the feasibility of implementing the technical solution of this application, but it does not mean that the applicant has or will necessarily use the solution.

[0038] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0039] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0040] Figure 1 The flowchart of a hinge point optimization method for a bulk material system dumping mechanism according to an embodiment of the present application is schematically shown, which can be used for the hinge point optimization process based on minimizing the oil cylinder force for dumping mechanisms including ear boxes. In addition, it should be noted that this patent provides hinge point optimization based on minimizing the oil cylinder force during the dumping process of a box bulk material system, and only the corn ear box is used as an example in this article. In addition, the hinge point optimization of the loading and unloading process involving discrete materials in other bulk materials such as minerals, crops, and food can also be performed with reference to the method proposed in this patent.

[0041] Specifically, the hinge point optimization method may include the following steps S110-S140.

[0042] Step S110: According to the initial hinge point information of the oil cylinder on the dumping mechanism, the angle time history curve and the force time history curve of the oil cylinder during the flipping process of the dumping mechanism are obtained by using the multi-body dynamics-discrete element coupling modeling method.

[0043] The initial hinge point information may include the initial position information of at least two fixed hinge points and at least one mobile hinge point. For example, the initial hinge point information may include the first fixed hinge point, the second fixed hinge point, and the mobile hinge point. In other words, a "multi-body dynamics + discrete element" coupling analysis model may be established based on the initial hinge point information of the existing dumping mechanism and the discrete material parameters in the box, such as Figure 2 shown.

[0044] In the embodiment of the present application, step S110 may further include the following steps S111 - S114 .

[0045] Step S111: establishing a multi-body dynamics model based on the connection relationship between the dumping mechanism, the hinge point and the cylinder.

[0046] The connection relationship may include the rotational connection relationship between the tipping mechanism and the hinges, and the sliding connection relationship between the cylinder and the hinges. Specifically, in the multi-body dynamics model, the connection pairs between the components must be established first. For example, the connection between the hinges can be set as a rotational connection pair, that is, the two bodies can rotate freely around an axis, which is called an articulated relationship, and the hinge point is called a hinge; the connection between the cylinder and the hinge point is set as a sliding connection pair, that is, the rod of the cylinder can slide in the cylinder barrel of the cylinder.

[0047] Specifically, Figure 3 The hinge information of the dumping mechanism in an embodiment is given in the figure, which adopts the layout of a single-side oil cylinder. Among them, A, B, and C are the initial hinges of the dumping mechanism, hinges A and B are fixed hinges, and their positions do not change with the rotation of the dumping mechanism. Hinge C is a mobile hinge, and C' is the new hinge position after C moves during the pushing process. Among them, La0 is the distance between AB, and Lb0 is the distance between AC, both of which are fixed values; the distance Lc between BC is the length of the oil cylinder, which changes with the position of the mobile hinge C, and Lc1 is the length of the oil cylinder in the initial state.

[0048] Step S112: establishing a discrete element model based on discrete material parameters in the dumping mechanism, wherein the discrete material parameters may include the mass of the discrete material, the shape of the discrete material pile, the first contact parameter between the discrete materials, and the second contact parameter between the discrete material and the wall of the box.

[0049] Among them, discrete material parameters are, for example, ear parameters. In the actual modeling process of the ear, the load of the ear involves the contact calculation between particles and between particles and the wall. Therefore, if the model is completely based on the actual situation and the contact model between the ears is directly used as the objective function, the modeling process is more complicated and the simulation calculation efficiency is slower, which will lead to low overall optimization efficiency. In this regard, the applicant considers that the load source, except for the deadweight of the box itself, the application of the remaining loads only comes from the discrete system of the ear.

[0050] Therefore, this paper proposes the need to establish a discrete model of corn ears (including particle size, shape, size distribution, etc.) based on the ear parameters in the ear box, that is, at each tilt angle, the contact parameters between corn ears and the box wall (static and dynamic friction coefficients, rebound coefficient, etc.) and other boundary conditions are used to determine the shape and total mass of the ear pile. Then, the ear pile at this tilt angle is regarded as a whole, and the compressive stress on the ear box is calculated by the total mass of the remaining ears. In this way, only the input parameters such as the shape and total mass of the ear pile are needed, combined with the boundary conditions such as the contact parameters between corn ears and the box wall (static and dynamic friction coefficients, rebound coefficient, etc.).

[0051] At the same time, in order to ensure the coupling relationship with the multi-body dynamics model, the total simulation time of the discrete model should be consistent with that of the corresponding multi-body dynamics.

[0052] Step S113: determining the angle time history curve of the cylinder during the turning process of the dumping mechanism based on the pushing speed of the cylinder and the multi-body dynamics model.

[0053] Among them, the pushing speed of this application should be less than the set speed. This is because the load borne by the oil cylinder is provided by the deadweight of the silo itself and the ear particles in the silo. In order to avoid the phenomenon that the oil cylinder pushes too fast, resulting in the rapid fall of particles and causing an instantaneous surge in the force of the oil cylinder, a safer and more reasonable pushing speed is set in the model. For example, in the model calculation, the oil cylinder is used as the drive, and the total pushing stroke is pushed linearly within the total simulation time. The total simulation time is more than 1.2 times the actual pushing time, preferably more than 1.5 times, so as to ensure that each tilt angle is approximately static.

[0054] Then, during the pushing process, the cylinder stroke and the box flip angle are in a one-to-one correspondence, which can be represented by a mathematical expression. Figure 3 From the schematic diagram of the single-side oil cylinder, we can see that Lc1 is the length of the oil cylinder in the initial state, and Lc(t) is the length of the oil cylinder during the driving process, which changes with the pushing time t. Based on the pushing speed v (mm / s) of the oil cylinder, we can first determine the change curve Lc(t) of the oil cylinder length with the pushing time t using the following formula:

[0055] Lc(t)=Lc1+v*t

[0056] Furthermore, θ(t) is defined as the set angle between AC and AB, and k0 is the initial angle of the set angle. Then the angle time history curve θ(t) with the pushing time t can be determined by the following formula:

[0057]

[0058] Wherein, Lc1 is the length of the cylinder in the initial state, Lc(t) is the length of the cylinder during the driving process; La0 is the initial distance of the line segment AB formed by the first fixed hinge point A and the second fixed hinge point B, Lb0 is the initial distance of the line segment AC formed by the first fixed hinge point A and the movable hinge point C; the set angle is the angle formed by taking the first fixed hinge point A as the vertex and the line segments AC and AB as the sides, and k0 is the initial angle of the set angle.

[0059] Step S114: coupling the discrete element model with the multi-body dynamics model to determine the force time history curve of the oil cylinder during the tipping process of the dumping mechanism.

[0060] In the embodiment of the present application, the box flipping motion of multi-body dynamics can be used as the boundary condition of particle motion through the coupling calculation of multi-body dynamics and discrete elements. At the same time, the load on the box wall is applied through the discrete system to calculate the required cylinder driving force. The two are transmitted synchronously in real time to realize real-time simulation calculation of the cylinder force of discrete materials during the dumping process.

[0061] Specifically, the technical route for solving the cylinder force time history curve of this application can be found in Figure 4 , the discrete element model can be coupled with the multi-body dynamics model through the pushing time t. That is, firstly, the angle time history curve θ(t) is obtained through the multi-body dynamics model, and then the shape and total mass of the ear pile at the angle θ(t) are obtained through the discrete element model, and then the compressive stress on the dumping mechanism is calculated. Through the above processing steps, the cylinder force time history curve of the single-side cylinder in the uniform speed pushing process can be extracted.

[0062] Step S120: determining an angle-torque time-history curve between the tipping angle of the dumping mechanism and the applied torque of the oil cylinder according to the angle-time-history curve and the force-time-history curve.

[0063] from Figure 3 It can be seen that the lever arm of the oil cylinder on the dumping mechanism is the distance from A to BC'. Therefore, based on the angle time history curve θ(t), the lever arm time history curve l(t) of the lever arm of the oil cylinder on the dumping mechanism at the initial hinge position changing with time t can be characterized as:

[0064]

[0065] Therefore, the torque M(t) of the oil cylinder on the dumping mechanism can also be expressed as a curve that changes with time t, that is, the angle-torque time-history curve M(t) can be determined based on the angle-time-history curve θ(t) and the force-time-history curve F(t) by the following formula:

[0066] M(t)=F(t)*l(t)

[0067] Among them, l(t) is the time history curve of the force arm of the cylinder on the dumping mechanism at the initial hinge position.

[0068] Step S130: Optimize and change the hinge position of the cylinder on the dumping mechanism based on the angle-torque time-history curve and the constraint conditions of the cylinder to determine the maximum applied force of the cylinder at different hinge positions.

[0069] In step S130, in order to achieve the optimal change of the hinge position, this embodiment proposes a method of replacing the load transfer method of the discrete system with an equivalent bending moment to calculate the stress curves in different hinge positions. The physical significance of this method is that the total bending moment applied by the discrete particles to the wall is only related to the shape of the particles in the box, and the shape of the ear pile of the particles in the box is only related to the flip angle of the box. Therefore, in the established optimization model, it is only necessary to ensure that the time rate of change of the flip angle θ(t) of the box in the optimization model is consistent (that is, the angular velocity is consistent, which can be achieved by reducing the pushing speed so that both are similar to the static model), and the same bending moment dynamic curve M(t) can be applied to optimize the hinge under equivalent load.

[0070] Specifically, step S130 may further include the following steps S131-S133:

[0071] Step S131: change the positions of the second fixed hinge point and the movable hinge point to determine a first distance between the first fixed hinge point and the second fixed hinge point, and a second distance between the first fixed hinge point and the movable hinge point.

[0072] For example, the hinge position of the oil cylinder on the dumping mechanism can be optimized and changed by at least one of the following algorithms: genetic algorithm, downhill method, annealing method, etc. Then, the first distance between the first fixed hinge point and the second fixed hinge point, and the second distance between the first fixed hinge point and the movable hinge point can be obtained as a reference for subsequent calculations.

[0073] Figure 5 The initial hinge point of the dumping mechanism and the hinge point information during the flipping process are given in , where A is the coordinate origin (0,0), the coordinates of the two sets of hinge points B and C are set to (X1,Y1) and (X2,Y2) respectively, La is the first distance between AB, and Lb is the second distance between AC, both of which are constants:

[0074]

[0075] In addition, the distance between BC is the cylinder length Lc, Lc0 is the cylinder length in the initial state, and Lc(t) is the cylinder length during the driving process. In the initial hinge information, the angle ∠CAB between AC and AB is a fixed value k, while the angle ∠C'AB between AC and AB during the cylinder pushing process is k+θ, where θ is the angle of rotation of the silo.

[0076] Step S132: Determine, based on the first distance and the second distance, a time history curve of the lever arm of the oil cylinder on the dumping mechanism when the hinge position is changed to be optimized.

[0077] Among them, Figure 5 As shown, the lever arm corresponding to the cylinder force is the distance from A to BC'. Therefore, the lever arm time history curve D of the cylinder to the dumping mechanism under the optimized change of the hinge position can be determined according to the first distance La and the second distance Lb. CYL (t):

[0078]

[0079] Among them, the position information of the first fixed hinge point is the origin (0,0), the changed position information of the second fixed hinge point is (X1,Y1), and the changed position information of the movable hinge point is (X2,Y2); k is the initial angle of the set angle at the initial hinge point position, and θ(t) is the angle time curve of the set angle at the initial hinge point position.

[0080] Step S133: Determine the maximum applied force of the oil cylinder at the hinge position according to the lever arm time history curve and the angle torque time history curve.

[0081] Through the above steps, according to the force arm time history curve D CYL (t) and the angle-torque time history curve M(t), the following formula is used to determine the required cylinder force curve F at different hinge positions CYL (t):

[0082]

[0083] Then, the cylinder force curve F can be defined CYL The maximum value in (t) is F CYL_MAX Therefore, for each set of hinge information, the maximum cylinder force F under this set of hinge information can be obtained. CYL_MAX :

[0084] F CYL_MAX =MAX{F CYL (t)}.

[0085] In addition, the constraints of the present application may include stability coefficients and minimum installation distance restrictions for the cylinders.

[0086] First, as a pressure-bearing component, the cylinder is prone to instability. The following formula can be used to determine its critical instability load F CR (t):

[0087]

[0088] Wherein: E is the elastic model modulus, which is only related to the material properties and can be regarded as a constant; I is the moment of inertia, which is only related to the rod diameter. In the optimization calculation process of the present invention, the cylinder rod diameter is also regarded as a constant.

[0089] Substituting the above Lc(t) into this formula, we get:

[0090]

[0091] Furthermore, the instability coefficient curve K can be defined CR (t):

[0092]

[0093] Generally speaking, in order to make the stability coefficient meet the safety requirements, the maximum value in the instability coefficient curve can be defined as K CR_MAX Therefore, for each set of hinge information, the minimum instability coefficient K under this set of hinge information can be obtained. CR_MAX :

[0094] K CR_MAX =MAX{K CR (t)}

[0095] Among them, K can be defined CR_safe is the allowable safety instability factor, if K CR_MAX >K CR_safe , it means that the cylinder will become unstable; if K CR_MAX <K CR_safe , it means that the oil cylinder is more stable and not easy to become unstable. Therefore, in the optimization process, the following formula can be used as one of the constraints:

[0096] K CR_MAX <K CR_safe .

[0097] Secondly, there is a minimum installation distance limit in the cylinder design:

[0098] The shortest distance between the cylinder hinge points>cylinder stroke+cylinder dead stroke.

[0099] That is, cylinder stroke = maximum cylinder distance MAX{Lc(t)} minus minimum cylinder distance MIN{Lc(t)}.

[0100] Among them, the cylinder dead distance Lc_death is usually a fixed value. Therefore, the requirements for the minimum installation distance limit of the cylinder should meet the following requirements:

[0101] MIN{Lc(t)}>MAX{Lc(t)}-MIN{Lc(t)}+Lc_death

[0102] Therefore, the following formula can be used as another constraint:

[0103] MIN{Lc(t)}>0.5*[MAX{Lc(t)}+Lc_death].

[0104] Referring to the above constraints on the hinge position, define X 1min , X 1max is the constraint range of the horizontal coordinate of the hinge point B, Y 1min , Y 1max is the constraint range of the ordinate of the hinge point B, X 2min , X 2max is the constraint range of the horizontal coordinate of the hinge point C, Y 2min , Y 2max is the constraint range of the ordinate of the hinge point C, then the coordinate parameter range of the hinge points B and C satisfies:

[0105] X 1min <X1<X 1max

[0106] Y 1min <Y1<Y 1max

[0107] X 2min <X2<X 2max

[0108] Y 2min <Y2<Y 2max

[0109] For example, the two hinge points B and C can be limited to Figure 6 within the rectangular frame shown.

[0110] Step S140: Determine the hinge point position with the smallest maximum applied force as the target hinge point position

[0111] As mentioned above, the optimization model can be optimized under the defined constraints by using relevant optimization algorithms such as genetic algorithm, downhill method, annealing method, etc. to obtain multiple sets of hinge position. After multiple rounds of iterative optimization calculations, if the residual of the minimum value of the objective function reaches stability, it can be considered that the minimum value of the objective function has been found, that is, the hinge position information corresponding to the minimum cylinder force that meets the critical instability coefficient of the cylinder has been found.

[0112] In summary, existing technologies usually use multi-body dynamics combined with parameter optimization to minimize the cylinder force to achieve the optimization of the hinge position. However, this method cannot take into account the change in the center of gravity of the discrete material pile as the position changes, especially during the dumping process, the discrete materials in the bin decrease, and the cylinder force becomes smaller in the post-dumping stage. Therefore, the calculation of the cylinder force is inconsistent with the actual situation, which affects the subsequent selection of cylinder specifications and optimization of the hinge group.

[0113] The coupling model of "multi-body dynamics + discrete element" adopted in this technology realizes the extraction of the pushing cylinder force of the dumping mechanism loaded with discrete materials during the tipping operation, and can truly reflect the changes in the cylinder force of the dumping mechanism during the tipping process. Combined with the geometric tipping curve and bending moment dynamic curve of the dumping mechanism, an equivalent optimization mathematical model for the dumping mechanism is proposed, which provides feasibility for the subsequent optimization of the hinge group to minimize the cylinder force.

[0114] At the same time, in the process of establishing the optimization model, in order to improve the overall calculation efficiency, this paper equates the single optimization model of "multi-body dynamics + discrete element" (cylinder as drive, discrete system as load source) to the form of total bending moment (it only needs to ensure that the angular velocity of the box rotation in the two models is consistent, that is, the two are completely equivalent in the physical model), thereby obtaining the total bending moment value applied by the dumping mechanism and the discrete materials therein. Therefore, the coupling calculation process that originally took dozens of hours can be shortened to a few minutes, which provides computational feasibility for the optimization of hinge points in the bulk material box system.

[0115] on the other hand, Figure 7 A schematic diagram of a hinge point optimization system for a bulk material system dumping mechanism according to an embodiment of the present application is schematically shown. In the embodiment of the present application, the optimization system 200 may include:

[0116] The time history curve acquisition device 210 is used to acquire the angle time history curve and the force time history curve of the cylinder in the tipping process of the tipping mechanism in a multi-body dynamics-discrete element coupling modeling manner according to the initial hinge point information of the cylinder on the tipping mechanism, wherein the initial hinge point information may include the initial position information of at least two fixed hinge points and at least one mobile hinge point;

[0117] An angle-torque determination device 220, used to determine an angle-torque time-history curve between the tipping angle of the dumping mechanism and the applied torque of the oil cylinder according to the angle-time-history curve and the force-time-history curve;

[0118] A hinge point optimization and change device 230, used to optimize and change the hinge point position of the cylinder on the dumping mechanism based on the angle torque time history curve and the constraint conditions of the cylinder, so as to determine the maximum applied force of the cylinder at different hinge point positions; and

[0119] The target hinge point determining device 240 is used to determine the hinge point position with the smallest maximum applied force as the target hinge point position.

[0120] In the embodiment of the present application, the time-history curve acquisition device 210 is specifically used to perform: based on the connection relationship between the dumping mechanism, the hinge and the cylinder, a multi-body dynamics model is established, wherein the connection relationship includes the rotational connection relationship between the dumping mechanism and the hinge, and the sliding connection relationship between the cylinder and the hinge; based on the discrete material parameters in the dumping mechanism, a discrete element model is established, wherein the discrete material parameters include the mass of the discrete material, the morphology of the discrete material pile, the first contact parameters between the discrete materials (particle size, shape, size distribution, etc.) and the second contact parameters between the discrete materials and the wall of the box (static and dynamic friction coefficients, rebound coefficient, etc.); based on the pushing speed of the cylinder and the multi-body dynamics model, the angle time-history curve of the cylinder during the flipping process of the dumping mechanism is determined, wherein the pushing speed is less than the set speed; and the discrete element model is coupled with the multi-body dynamics model to determine the force time-history curve of the cylinder during the flipping process of the dumping mechanism.

[0121] In the embodiment of the present application, the initial hinge point information includes a first fixed hinge point, a second fixed hinge point and a mobile hinge point, and the angle time history curve of the cylinder during the flipping process of the dumping mechanism is determined based on the pushing speed of the cylinder and the multi-body dynamics model, including: based on the pushing speed v, the angle time history curve θ(t) of the set angle with the pushing time t is determined by the following formula:

[0122] Lc(t)=Lc1+v*t

[0123]

[0124] Among them, Lc1 is the length of the cylinder in the initial state, Lc(t) is the length of the cylinder during the driving process; La0 is the initial distance of the line segment AB formed by the first fixed hinge point A and the second fixed hinge point B, Lb0 is the initial distance of the line segment AC formed by the first fixed hinge point A and the movable hinge point C; the set angle is the angle formed with the first fixed hinge point A as the vertex and the line segment AC and the line segment AB as the sides, and k0 is the initial angle of the set angle.

[0125] In the embodiment of the present application, determining the angle-torque time-history curve between the flipping angle of the dumping mechanism and the applied torque of the cylinder according to the angle-time-history curve and the force-time-history curve includes: determining the angle-torque time-history curve M(t) according to the following formula based on the angle-time-history curve θ(t) and the force-time-history curve F(t):

[0126]

[0127] M(t)=F(t)*l(t)

[0128] Wherein, l(t) is the time history curve of the force arm of the oil cylinder on the dumping mechanism at the initial hinge position.

[0129] In an embodiment of the present application, the hinge position of the cylinder on the dumping mechanism is optimized and changed based on the angle-torque time-history curve and the constraint conditions of the cylinder to determine the maximum applied force of the cylinder at different hinge positions, including: changing the position of the second fixed hinge and the mobile hinge to determine a first distance between the first fixed hinge and the second fixed hinge, and a second distance between the first fixed hinge and the mobile hinge; determining a force arm time-history curve of the cylinder on the dumping mechanism under the optimized changed hinge position based on the first distance and the second distance; and determining the maximum applied force of the cylinder at the hinge position based on the force arm time-history curve and the angle-torque time-history curve.

[0130] In the embodiment of the present application, the determining of the arm time history curve of the oil cylinder to the dumping mechanism under the optimized changed hinge position according to the first distance and the second distance includes: determining the arm time history curve D of the oil cylinder to the dumping mechanism under the optimized changed hinge position according to the first distance La and the second distance Lb by the following formula: CyL (t):

[0131]

[0132]

[0133] Among them, the position information of the first fixed hinge point is the origin (0,0), the changed position information of the second fixed hinge point is (X1,Y1), and the changed position information of the movable hinge point is (X2,Y2); k is the initial angle of the set angle at the hinge point position, and θ(t) is the angle time curve of the set angle.

[0134] In the embodiment of the present application, the hinge point optimization and modification device 230 is specifically used to perform: according to the force arm time history curve D CYL (t) and the angle-torque time history curve M(t), the following formula is used to determine the maximum applied force F of the cylinder at the hinge position. CYL_MAX :

[0135]

[0136] F CYL_MAX =MAX{F CYL (t)}.

[0137] In the embodiment of the present application, the constraint conditions include a stability coefficient and a minimum installation distance limit of the oil cylinder.

[0138] In an embodiment of the present application, the hinge position of the oil cylinder on the dumping mechanism is optimized and changed by at least one of the following algorithms: genetic algorithm, downhill method, annealing method.

[0139] In summary, existing technologies usually use multi-body dynamics combined with parameter optimization to minimize the cylinder force to achieve the optimization of the hinge position. However, this method cannot take into account the change in the center of gravity of the discrete material pile as the position changes, especially during the dumping process, the discrete materials in the bin decrease, and the cylinder force becomes smaller in the post-dumping stage. Therefore, the calculation of the cylinder force is inconsistent with the actual situation, which affects the subsequent selection of cylinder specifications and optimization of the hinge group.

[0140] The coupling model of "multi-body dynamics + discrete element" adopted in this technology realizes the extraction of the pushing cylinder force of the dumping mechanism loaded with discrete materials during the tipping operation, and can truly reflect the changes in the cylinder force of the dumping mechanism during the tipping process. Combined with the geometric tipping curve and bending moment dynamic curve of the dumping mechanism, an equivalent optimization mathematical model for the dumping mechanism is proposed, which provides feasibility for the subsequent optimization of the hinge group to minimize the cylinder force.

[0141] At the same time, in the process of establishing the optimization model, in order to improve the overall calculation efficiency, this paper equates the single optimization model of "multi-body dynamics + discrete element" (cylinder as drive, discrete system as load source) to the form of total bending moment (it only needs to ensure that the angular velocity of the box rotation in the two models is consistent, that is, the two are completely equivalent in the physical model), thereby obtaining the total bending moment value applied by the dumping mechanism and the discrete materials therein. Therefore, the coupling calculation process that originally took dozens of hours can be shortened to a few minutes, which provides computational feasibility for the optimization of hinge points in the bulk material box system.

[0142] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0143] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A hinge point optimization method for a bulk material system dumping mechanism, characterized in that: The hinge point optimization method comprises: According to the initial hinge point information of the oil cylinder on the dumping mechanism, the angle time history curve and the force time history curve of the oil cylinder during the flipping process of the dumping mechanism are obtained by a multi-body dynamics-discrete element coupling modeling method, wherein the initial hinge point information includes initial position information of at least two fixed hinge points and at least one movable hinge point; Determine an angle-torque time-history curve between the tipping angle of the dumping mechanism and the applied torque of the oil cylinder according to the angle-time-history curve and the force-time-history curve; Optimizing and changing the hinge position of the cylinder on the dumping mechanism based on the angle-torque time-history curve and the constraint conditions of the cylinder to determine the maximum applied force of the cylinder at different hinge positions; and The hinge point position where the maximum applied force is the smallest is determined as the target hinge point position.

2. The hinge point optimization method of the bulk material system dumping mechanism according to claim 1 is characterized in that: The method of obtaining the angle time history curve and force time history curve of the cylinder during the flipping process of the dumping mechanism by means of multi-body dynamics-discrete element coupling modeling according to the initial hinge point information of the cylinder on the dumping mechanism includes: A multi-body dynamics model is established based on the connection relationship between the dumping mechanism, the hinge point and the oil cylinder, wherein the connection relationship includes the rotation connection relationship between the dumping mechanism and the hinge point, and the sliding connection relationship between the oil cylinder and the hinge point; A discrete element model is established based on discrete material parameters in the dumping mechanism, wherein the discrete material parameters include the mass of the discrete material, the shape of the discrete material pile, the first contact parameter between the discrete materials, and the second contact parameter between the discrete material and the wall of the box; Determining an angle time history curve of the oil cylinder during the tipping process of the dumping mechanism based on the pushing speed of the oil cylinder and the multi-body dynamics model, wherein the pushing speed is less than a set speed; and The discrete element model is coupled with the multi-body dynamics model to determine a force time history curve of the cylinder during the tipping process of the dumping mechanism.

3. The hinge point optimization method of the bulk material system dumping mechanism according to claim 2 is characterized in that: The initial hinge point information includes a first fixed hinge point, a second fixed hinge point and a mobile hinge point, The step of determining the angle time history curve of the oil cylinder during the flipping process of the dumping mechanism based on the pushing speed of the oil cylinder and the multi-body dynamics model includes: Based on the pushing speed v, the angle time curve θ(t) of the set angle with the pushing time t is determined by the following formula: Lc(t)=Lc1+v*t Wherein, Lc1 is the length of the cylinder in the initial state, and Lc(t) is the length of the cylinder during the driving process; La0 is the initial distance of the line segment AB formed by the first fixed hinge point A and the second fixed hinge point B, and Lb0 is the initial distance of the line segment AC formed by the first fixed hinge point A and the mobile hinge point C; The set angle is an angle formed by taking the first fixed hinge point A as a vertex and taking the line segment AC and the line segment AB as sides, and k0 is an initial angle of the set angle.

4. The hinge point optimization method of the bulk material system dumping mechanism according to claim 3 is characterized in that: The step of determining the angle-torque time-history curve between the flipping angle of the dumping mechanism and the applied torque of the oil cylinder according to the angle-time-history curve and the force-time-history curve comprises: Based on the angle time history curve θ(t) and the force time history curve F(t), the angle torque time history curve M(t) is determined by the following formula: M(t)=F(t)*l(t) Wherein, l(t) is the time history curve of the force arm of the oil cylinder on the dumping mechanism at the initial hinge position.

5. The hinge point optimization method of the bulk material system dumping mechanism according to claim 1, characterized in that: The optimizing and changing the hinge position of the oil cylinder on the dumping mechanism based on the angle-torque time-history curve and the constraint condition of the oil cylinder to determine the maximum applied force of the oil cylinder at different hinge positions includes: Changing the positions of the second fixed hinge point and the movable hinge point to determine a first distance between the first fixed hinge point and the second fixed hinge point, and a second distance between the first fixed hinge point and the movable hinge point; Determine, according to the first distance and the second distance, a time history curve of the force arm of the oil cylinder on the dumping mechanism when the hinge point position is changed in an optimized manner; and According to the lever arm time history curve and the angle torque time history curve, the maximum applied force of the oil cylinder at the hinge point position is determined.

6. The hinge point optimization method of the bulk material system dumping mechanism according to claim 5, characterized in that: The step of determining the time history curve of the lever arm of the oil cylinder on the dumping mechanism when the hinge position is changed optimally according to the first distance and the second distance comprises: According to the first distance La and the second distance Lb, the following formula is used to determine the time history curve D of the force arm of the oil cylinder on the dumping mechanism under the optimized change of the hinge position: CYL (t): The position information of the first fixed hinge is the origin (0,0), the changed position information of the second fixed hinge is (X1,Y1), and the changed position information of the movable hinge is (X2,Y2); k is the initial angle of the set angle at the initial hinge point position, and θ(t) is the angle time history curve of the set angle at the initial hinge point position.

7. The hinge point optimization method of the bulk material system dumping mechanism according to claim 5, characterized in that: Determining the maximum applied force of the oil cylinder at the hinge position according to the lever arm time history curve and the angle torque time history curve includes: According to the force arm time history curve D CYL (t) and the angle-torque time history curve M(t), the following formula is used to determine the maximum applied force F of the cylinder at the hinge position. CYL_MAX : F CYL_MAX =MAX{F CYL (t)}。 8. The hinge point optimization method of the bulk material system dumping mechanism according to claim 1, characterized in that: The constraint conditions include the stability coefficient and the minimum installation distance limit of the cylinder.

9. The hinge point optimization method of the bulk material system dumping mechanism according to claim 1, characterized in that: The hinge position of the oil cylinder on the dumping mechanism is optimized and changed by at least one of the following algorithms: genetic algorithm, downhill method, annealing method.

10. A hinge point optimization system for a bulk material system dumping mechanism, characterized in that: The hinge point optimization system comprises: A time history curve acquisition device is used to acquire an angle time history curve and a force time history curve of the oil cylinder during the tipping process of the dumping mechanism in a multi-body dynamics-discrete element coupling modeling manner according to initial hinge point information of the oil cylinder on the dumping mechanism, wherein the initial hinge point information includes initial position information of at least two fixed hinge points and at least one mobile hinge point; An angle-torque determination device, used for determining an angle-torque time-history curve between the flipping angle of the dumping mechanism and the applied torque of the oil cylinder according to the angle-time-history curve and the force-time-history curve; A hinge point optimization and change device, used for optimizing and changing the hinge point position of the cylinder on the dumping mechanism based on the angle torque time history curve and the constraint conditions of the cylinder, so as to determine the maximum applied force of the cylinder at different hinge point positions; and The target hinge point determination device is used to determine the hinge point position where the maximum applied force is the smallest as the target hinge point position.

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